Switchable optical filter and application thereof

Abstract

The invention relates to an optical assembly (1) which can be used in different embodiments of a switchable filter (5) in different designs, in addition to a polarizing filter (P) and / or other means for changing the polarization properties of light, such as a liquid crystal layer (3). The combination of the switchable optical filter (5) and the image reproduction device achieves a switchable peep-proof effect. The optical component (1) comprises a first layer (S1), or the first layer (S1) and a plurality of other layers (S2,...), where each layer (S1, S2,...) comprises a material having a plurality of light absorption transition dipole moments. Each transition dipole moment is oriented parallel to or fluctuates around a selectable preferred direction at least in a first state with a tolerance of maximum 10 DEG, such that light incident on the optical assembly is transmitted or at least partially absorbed depending on its direction of incidence with respect to the layers (S1, S2,...) and its polarization state.

Description

[0001] This application is a divisional application of an invention patent application with an application date of September 27, 2021, an entry into the Chinese national phase date of August 4, 2022, an application number of 202180012906.3, and an invention name of “Switchable optical filter and its application”. Background Art

[0002] In recent years, great progress has been made in widening the viewing angle of LCDs. However, in some cases, the visible range of very large screens can become a disadvantage. Mobile devices such as laptops and tablet computers also increasingly provide information, such as banking data or other personal and sensitive data. Accordingly, there is a need to control who should see this sensitive data; it is necessary to be able to choose within a wide viewing angle (public mode) to share the information on the display with others, for example when viewing holiday photos, and for advertising purposes. On the other hand, when it is desired to keep the image information confidential, a smaller viewing angle (private mode) is required.

[0003] Automotive engineering encounters a similar problem: the driver should not be distracted by graphic content, such as digital entertainment, after the engine is started, while passengers want to consume graphic content while driving as well. Therefore, a screen is required that can switch between the corresponding presentation modes.

[0004] Additional films based on micro-sheets have been used in mobile displays for visual data protection. However, the films are not switchable or convertible; they always have to be applied by hand and then removed. They also have to be transported separately from the display when not needed. Furthermore, the main disadvantage of using such sheet-like films is the light loss that accompanies them.

[0005] US6765550B2 describes a privacy protection by micro-lamellae. The major disadvantages are the mechanical removal or mechanical mounting of the filter and the light loss in the protection mode.

[0006] US5993940A describes the use of a film having uniformly distributed, small strip-shaped prisms on its surface to achieve a private mode, that is, a restrictive viewing angle mode with a small viewing angle range. The technical difficulty of research and development and manufacturing is quite large.

[0007] In WO2012 / 033583A1, the switching between free field of view and restricted field of view is realized by controlling the liquid crystal between the so-called "chromonisch" layers, which causes light loss and is technically very difficult.

[0008] US2012 / 0235891A1 describes a very complex backlight in a screen. Fig.15, not only multiple light guides are used, but also other complex optical components such as a microlens assembly 40 and a prism structure 50 that convert the backlight into the frontlight are used. Its implementation cost is high, the technical implementation is complex, and it also causes light loss. According to the modified example shown in Figure 17 of US2012 / 0235891A1, both light sources 4R and 18 generate light with a narrow illumination angle, wherein the light from the rear light source 18 is converted into light with a large illumination angle after a complex process. As mentioned above, such a complex conversion greatly reduces the brightness.

[0009] According to JP2007-155783A, an optical surface 19 is used, which is complex to calculate and manufacture, and deflects light to different narrow or wide areas according to the incident angle of the light. The structure is similar to a Fresnel lens. In addition, there are interfering side surfaces that deflect light in an undesirable direction. In this way, it is uncertain whether a truly reasonable light distribution can be achieved.

[0010] US2013 / 0308185A1 describes a special light guide having steps, which directs light from a narrow surface to a large surface according to the direction in which the light guide is illuminated. In combination with a transmissive image reproduction device such as an LC display, it is thus possible to produce a screen that can be switched between a free view mode and a restricted view mode. The main disadvantage is that the restricted view effect can only be produced for the left / right or up / down, but not for both, which is necessary for certain payment processes, for example. Furthermore, even in the restricted view mode, residual light can still be seen from obstructed viewing angles.

[0011] WO2015 / 121398A1 of the present applicant describes a screen with two working modes, wherein, in order to achieve the switching of the working modes, scattering particles are present in the volume of the corresponding light guide. However, the scattering particles of the polymer selected in this case generally have the following disadvantages, namely, the light from the two large surfaces is decoupled (ausgekoppelt), so that about half of the useful light is reflected in the wrong direction, i.e., emitted in the direction of the backlight, and cannot be recovered to a sufficient extent due to structural reasons. In addition, the scattering particles of the polymer distributed in the volume of the light guide may, in some cases, especially at higher concentrations, produce a scattering effect that reduces the anti-peeping effect in the protection mode.

[0012] The "electrical birefringence (EDB)" technology is based on the idea of ​​"filtering" all light beams that do not emerge from the imaging layer at a specific emission angle using the switchable liquid crystals of an additionally applied LC panel. The disadvantages of this technology are the additional energy and cost expenditures, as well as the difficult-to-change sweet spot of + / -40°, i.e. the optimal viewing position. Since the light intensity attenuation rises again for viewing angles beyond the sweet spot, the absorption of the LC structure is also insufficient, so that for viewing angles greater than + / -40°, the light intensity is at most 3% of the maximum light intensity.

[0013] The above methods and configurations generally have the disadvantages of significantly reducing the brightness of the basic screen and / or requiring complex and expensive optical components for mode conversion and / or reducing the resolution in the free-viewing common mode and / or having visual artifacts when the display resolution is very high. Summary of the invention

[0014] The object of the present invention is therefore to disclose a switchable filter with an optical component, wherein light incident on the optical component is transmitted or partially or completely absorbed depending on its direction of incidence and polarization properties (but not on its position). By using a switchable filter with this optical component, it is intended to exert an angle-dependent (optionally perpendicular to a sitting or standing viewer) influence on the transmission of light, wherein it is possible to switch between at least two operating states. In particular, a transmission angle limitation in certain directions should be switchable.

[0015] The optical component or a system based on the optical component should be realizable at low cost and, in particular, should be universally applicable to different types of screens to enable switching between privacy protection (i.e., restricted field of view mode) and free field of view mode (at least in the horizontal direction relative to a standing or seated viewer), wherein the resolution of such a screen should not be substantially reduced.

[0016] In a first technical solution, this object is achieved by a switchable optical filter, which includes a first optical component that is not switchable per se. The optical component includes: a first layer, or the first layer and a plurality of other layers, preferably five or more. Each of the layers includes: a material having a plurality of light-absorbing transition dipole moments, wherein each transition dipole moment is oriented parallel to a first preferred direction selectable for the first optical component or fluctuates around the first preferred direction with a tolerance of up to 10° at least in a first state, so that light incident on the first optical component is transmitted or at least partially absorbed according to its incident direction relative to the layers and its polarization state.

[0017] The transition dipole moment (also called transition matrix element) is a quantum mechanical vector and belongs to a specific transition between an initial state (usually the ground state) and a final state (usually an excited state) of a system, i.e. an atom, a molecule or a solid, and corresponds to the electric dipole moment associated with this transition. The direction of the vector defines the polarization of the transition, which in turn determines how a system with electromagnetic waves interacts with a given polarization when transitioning from the ground state to an excited state that, for example, absorbs light of the corresponding polarization direction. The absolute value of the vector corresponds to the strength of the interaction or the transition probability.

[0018] For a given propagation direction of the light, the first preferred direction corresponds to an orientation of the transition dipole moment such that the absorption is the same for any polarization direction of the light. The preferred direction is the orientation of the transition dipole in the medium such that, in the privacy protection mode of operation described further below, the absorption is minimal for propagation in this direction in the medium.

[0019] As materials in the sense of the invention containing an orientable transition dipole moment, for example, dichroic dyes or dye mixtures in combination with a carrier material (e.g., liquid crystals or polymers) which do not impair the properties are suitable. For example, each of the layers may contain, for example, only one dye, wherein the dyes differ from one another in pairs for different layers. However, it is also possible for a single layer to contain several dyes, i.e., a dye mixture.

[0020] The switchable filter further comprises: a polarization filter and a member for selectively generating a first electric field or a second electric field, wherein the polarization filter is arranged upstream or downstream of the first optical component in the incident direction. A liquid crystal layer is provided between the first optical component and the polarization filter, the first electric field or the second electric field acts on the liquid crystal layer, and the liquid crystal layer accordingly affects the polarization state of light passing through the liquid crystal layer. The switchable filter can operate in at least two operating modes, wherein in a first operating mode B1 to which a first electric field is applied and which has a first sub-operating mode B1H and a second sub-operating mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter parallel to the first preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter at an angle of more than 30° to the first preferred direction is absorbed, wherein the absorption occurs only in the first direction in the first sub-operating mode B1H, and only in the second direction perpendicular to the first direction in the second sub-operating mode B1V. In the second operating mode B2, in which a second electric field is applied and which has a first sub-operating mode B1H and a second sub-operating mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter parallel to the first preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter (5) at an angle of more than 30° to the first preferred direction is absorbed, wherein the absorption occurs only in the second direction in the first sub-operating mode B1H and only in the second direction perpendicular to the first direction in the second sub-operating mode B1V, so that the absorption directions of each of the two sub-operating modes B1H and B1V differ by 90° for the first operating mode B1 and the second operating mode B2, and therefore also for both operating modes B1 and B2. Absorption always occurs only in one direction, that is, light is transmitted in the other direction.

[0021] In the first operating mode B1, in the sub-operating mode B1H, the absorption may occur, for example, in the horizontal direction with reference to a sitting or standing viewer or generally with reference to the eye position, and in the sub-operating mode B1V, the absorption may occur in the vertical direction, here also with reference to a sitting or standing viewer or generally with reference to the eye position. In this case, the straight line connecting the two eyes defines the horizontal direction and corresponds to the first direction, while the vertical direction is perpendicular to the horizontal direction and corresponds to the second direction. Correspondingly, in the second operating mode B2, in the sub-operating mode B1H, the absorption occurs in the vertical direction, and in the sub-operating mode B1V, the absorption occurs in the horizontal direction.

[0022] The configuration of the first technical solution of the switchable filter can be changed between the operating modes B1 and B2 or between B1H and B1V by rotating the polarization filter by 90°.

[0023] The field-free state can be described, for example, by the first electric field or the second electric field, and the other electric field has an absolute field strength greater than zero (e.g., 0.5 MV / m). In addition, depending on the design of the first optical component and the polarization filter, the field-free state may mean the existence of the operating mode B1 or B1H. However, the operating mode B2 or B1V may also exist in the field-free state.

[0024] Thus, the switchable filter of the first technical solution, in cooperation with the image reproduction unit, allows, for example, switching between vertical privacy protection and horizontal privacy protection (in working mode B1, for example, up / down protection in sub-working mode B1V and left / right protection in sub-working mode B1H). Taking a laptop computer as an example, this means that in working mode B1, a user can watch content with other people around the user whose eyes are substantially at the same height in sub-working mode B1V, and in sub-working mode B1H, people nearby cannot see the image content.

[0025] In fact, in working mode B1, the light emission angle range is vertically clipped, i.e. reduced, in sub-working mode B1V, and horizontally clipped, i.e. reduced, in sub-working mode B1H. In working mode B2, the corresponding relationship is reversed. Both are working modes in which the emission angle range is limited in one direction.

[0026] The switchable filter of the first technical solution can change its structure. Some important structural variations are given in Table 1 below. Among them, the first-mentioned elements always face the viewer, and the other components follow. In this case, the abbreviation "L / R" means that the optical effect is effective in the horizontal direction (the horizontal direction is defined above). For the polarization filter, this means that the polarization filter transmits horizontal linear polarized light and (substantially) absorbs vertical linear polarized light. Correspondingly, "O / U" means for the polarization filter that the polarization filter transmits vertical linear polarized light and (substantially) absorbs horizontal linear polarized light. And for the effect produced by the switchable filter in cooperation with the image reproduction unit that can be arranged before or after the switchable filter, the abbreviation "L / R" means that the anti-peeping effect acts horizontally, that is, blocking the left and right sights. It ultimately corresponds to the working mode B1 under the sub-working mode B1H of the switchable filter. Similarly, for the switchable filter in cooperation with the image reproduction unit, "O / U" means that the anti-peeping effect acts vertically, that is, blocking the upper and lower sights. It corresponds to the operating mode B1 in the sub-operating mode B1V of the switchable optical filter.

[0027] Table 1:

[0028]

[0029] In the example given in Table 1, the liquid crystal layer is a nematic liquid crystal layer rotated by 90°, that is, the preferred orientations of the liquid crystals on both surfaces that induce orientation and limit the liquid crystal layer are orthogonal to each other. In the case of the last row of the table, in state B1, the incident light is linearly polarized in the vertical direction (O / U) through the polarizer. Subsequently, through the liquid crystal layer, the linear polarization is rotated by 90° and then oriented horizontally (L / R). The smaller the angle between the horizontal direction and the incident direction, the lower the transmittance of the light. The privacy protection along the horizontal direction (L / R) is based on this. In the case of state B2, a similar relationship applies, but the 90° polarization change is cancelled.

[0030] It is pointed out here again that the "O / U" privacy effect in many practical cases allows normal viewing for multiple viewers when they observe from approximately the same height laterally of the image reproduction unit.

[0031] This object can also be achieved by a second technical solution of a switchable filter. This switchable filter also includes: a first optical component, which is similar to the first optical component of the first technical solution, but is switchable and also has the following characteristics: the transition dipole moment of each layer can change its orientation and / or its absolute value between a first state and at least one second state, so that each layer can be alternately placed in at least two different states. Here, a polarization filter is also provided upstream or downstream of the first optical component. The switchable filter according to the second technical solution also includes a component for selectively generating a first electric field or a second electric field, wherein, for the first optical component, the first state is generated by applying a first electric field, and the second state is generated by applying a second electric field.

[0032] In the first operating mode B1, a first electric field is applied and the transition dipole moment of the first optical component layer is oriented along a first preferred direction. Typically, the electric field of this switchable filter and all other switchable filters described above or below is V RMS A square wave voltage of <10V and a frequency of 1kHz is generated. The first working mode B1 includes a first sub-working mode B1H and a second sub-working mode B1V. In the first working mode B1, on the one hand, at least 24% of the non-polarized light incident on the switchable filter parallel to the first preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter according to the second technical solution at an angle of more than 30° to the first preferred direction is absorbed, wherein this absorption occurs only in the first direction in the first sub-working mode B1H, and only in the second direction perpendicular to the first direction in the second sub-working mode B1V.

[0033] In the second operating mode B3, a second electric field is applied and the transition dipole moment of the layer of the first optical component (1) is oriented parallel to the surface of the polarization filter and perpendicular to the transmission direction of the polarization filter. In this case, at least 24% of the unpolarized light incident on the switchable filter at any angle to the first preferred direction is transmitted.

[0034] Here, the field-free state can also be described, for example, by the first electric field or the second electric field, while the other electric field has an absolute field strength greater than zero (e.g. 0.5 MV / m). In addition, depending on the design of the optical components and the polarization filter, the field-free state may mean that the operating mode B3 is present. However, it is also possible that the operating mode B1 and one of the sub-operating modes B1H or B1V are present in the field-free state.

[0035] Thus, when the first direction is equated with the horizontal direction and the second direction is equated with the vertical direction similar to the first technical solution, the switchable filter of the second technical solution, in cooperation with the image reproduction unit, allows switching between anti-peeping protection in the vertical direction (blocking the upper / lower sight lines by a limited emission angle range in the sub-working mode B1V) or anti-peeping protection in the horizontal direction (blocking the left and right sight lines by a limited emission angle range in the sub-working mode B1H) and no anti-peeping effect (in the working mode B3, the emission angle range is not limited and is significantly larger than the emission angle range in the working mode B1 with two sub-working modes B1V and B1H). Different from the first technical solution, the working mode B3 realizes an omnidirectional free field of view mode.

[0036] In the third technical solution, the switchable filter comprises: a first optical component and a second optical component which are not switchable by themselves. Each of the two optical components (whose structure and working principle are described below) comprises: a first layer, or a first layer and a plurality of other layers, preferably five or more. Each of the layers comprises: a material having a plurality of light-absorbing transition dipole moments. Each transition dipole moment is oriented or fluctuates parallel to a first preferred direction selectable for the first optical component and a second preferred direction selectable for the second optical component with a tolerance of a maximum of 10°, at least in the first state. The first and second preferred directions differ from each other by less than 40°, preferably less than 20°, and more preferably less than 10°, including the case where the two can also be the same, that is, differ from each other by 0°. Light incident on the first or second optical component is transmitted or at least partially absorbed depending on its incident direction relative to the layer and its polarization state.

[0037] A liquid crystal layer is provided between the first optical component and the second optical component, and the liquid crystal layer affects the polarization state of light passing through the liquid crystal layer according to the first electric field or the second electric field acting on the liquid crystal layer. The switchable filter in the third technical solution also includes: a component for selectively generating the first and second electric fields, such as a transparent ITO electrode (ITO-Indium Tin Oxide). In addition, the switchable filter selectively includes a polarization filter arranged above or below the unit including the two optical components, or does not include a polarization filter.

[0038] In the case where a polarization filter is present, in the first operating mode B1 to which a first electric field is applied and which has a first sub-operating mode B1H and a second sub-operating mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter parallel to the first preferred direction or the second preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter at an angle of more than 30° to the corresponding preferred direction is absorbed, wherein this absorption occurs only in the first direction in the first sub-operating mode B1H and only in the second direction perpendicular to the first direction in the second sub-operating mode B1V, wherein the first direction or the second direction is perpendicular to the polarization direction of the polarization filter.

[0039] For another case where there is no polarization filter, in the first operation mode B1 with the first electric field applied, at least 24% of the unpolarized light incident on the switchable filter at any angle is transmitted.

[0040] Regardless of whether a polarization filter is present, in a second operating mode B2 in which a second electric field is applied, on the one hand, at least 24% of the non-polarized light incident on the switchable filter parallel to the first preferred direction or the second preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter at an angle of more than 30° to the corresponding preferred direction is absorbed.

[0041] As mentioned above, the two preferred directions of the two optical components can be identical or can differ from each other by an angle of at most 40°, preferably 20° or only 10°. When the filter is oriented at the surface normal of the filter, the range of emission angles corresponding to the viewing angle range is limited to the range around the surface normal because the transmittance is always maximum in the preferred direction. Therefore, by tilting one or both preferred directions, the angle at which the transmittance is maximum is also tilted, and the limiting viewing angle range is tilted accordingly.

[0042] In the case where non-polarized light is incident on the first optical component and then undergoes a 90° polarization rotation through the liquid crystal layer in the absence of an electric field, the viewing angle range is limited to the left, right, up and down. If the electromagnetic field is turned on at this time, the polarization rotation of the light does not occur, and the viewing angle range is not limited, but the light is polarized perpendicularly to the projection of the light incident vector on the light incident plane. If the light incident on the first optical component passes through the polarizer and undergoes linear polarization, the viewing angle is limited upward, downward, right and left in the absence of an electric field. If an electric field is applied at this time, the viewing angle is limited parallel to the linear polarization of the light incident on the first optical component.

[0043] Thus, the switchable filter of the third technical solution, in cooperation with the image reproduction unit, allows switching between two-sided privacy protection (for example, privacy protection upward and downward in sub-operating mode B1V) and four-sided privacy protection (in operating mode B2, the viewing angle range is limited in the four directions of up / down / left / right) in the presence of a polarizing filter, or, in the absence of a polarizing filter P, allows switching between omnidirectional free viewing with an unlimited viewing angle range in operating mode B1 and four-sided privacy protection in operating mode B2. Additional delay plate Can be used to influence the polarization state. For example, if a λ / 4 plate is used, linear polarized light is converted to circular polarized light and switched between four-sided privacy protection and unrestricted viewing.

[0044] In this case, for example, the field-free state can be described by the first electric field or the second electric field, while the other electric field has an absolute field strength greater than zero (e.g., 0.5 MV / m). In addition, depending on the design of the two optical components, the field-free state may mean that the operating mode B2 exists. However, it is also possible that the operating mode B1 (without polarizer) or one of the sub-operating modes B1H, B1V (with polarizer) exists in the field-free state.

[0045] In a fourth technical solution, the switchable filter also includes a first optical component and a second optical component. Unlike the third technical solution, the first optical component and the second optical component are switchable. Each of the two optical components includes: a first layer, or a first layer and a plurality of other layers, preferably more than five. Each of the layers includes: a material having a plurality of light-absorbing transition dipole moments. Each transition dipole moment is oriented or fluctuates parallel to a first preferred direction selectable for the first optical component (1) and a second preferred direction selectable for the second optical component (2) with a tolerance of up to 10° at least in a first state. Light incident on the first or second optical component is transmitted or at least partially absorbed depending on its incident direction relative to the layer and its polarization state. Unlike the third technical solution, here, the transition dipole moment of each of the layers can change its orientation and / or its absolute value between a first state and at least one second state, so that each layer is alternately placed in at least two different states.

[0046] In a fourth technical solution of the switchable filter, the switchable filter further comprises a member for selectively generating a first electric field or a second electric field, wherein, for each of the two optical components, the first state is generated by applying the first electric field, and the second state is generated by applying the second electric field. Thus, two electric fields are applied to the two optical components at the same time, however, still one of the two electric fields can also mean a state without electric field. An optical anisotropic layer is provided between the two optical components, which rotates the polarization direction of light passing through the alignment layer by 90°. The alignment layer is composed of, for example, a uniaxial twisted material (similar to a TN unit (TN=twiste dnematic), also known as a Schadt-Helfrich unit), and / or an optically active material.

[0047] It is possible to selectively place a polarization filter above or below the two optical components (understood as one unit) or not. A polarization filter is optional but can improve the performance of the switchable filter. The polarization of the polarization filter and the polarization of the incident light must be completely consistent.

[0048] In the fourth technical solution, in a first operating mode B1 in which a first electric field is applied, at least 24% of the unpolarized light incident on the switchable filter at an arbitrary angle to the switchable filter is transmitted, wherein, in the first operating mode B1, the transition dipole moments of the two optical components are oriented perpendicular to each other, and if a polarization filter is present, the polarization filter transition dipole component (Polarisationsfilter- ) is oriented parallel to the transition dipole moment of the switchable optical component closest to the polarization filter. In a second operating mode B2 with a second electric field applied, on the one hand, at least 24% of the non-polarized light incident on the switchable filter parallel to the first preferred direction or the second preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter at an angle of more than 30° to the corresponding preferred direction is absorbed, wherein, in operating mode B2, when a polarization filter is present, the transition dipole moment of the polarization filter and the transition dipole moment of the switchable optical component closest to the polarization filter are oriented perpendicular to each other, and the transition dipole moments of the two optical components are always oriented parallel to each other.

[0049] Thus, the switchable filter of the fourth technical solution, in cooperation with the image reproduction unit, allows switching between free viewing in all directions in the public or free working mode B1 and four-sided anti-peep protection in the private or restrictive working mode B2 with a limited viewing angle or exit angle range compared to the working mode B1, which is upward, downward, right and left relative to the preferred direction. When non-polarized light is incident on the switchable filter in the private working mode B2, light that is not approximately parallel to the preferred direction (preferably oriented parallel in the working mode B2) is absorbed. In the public working mode B1, linearly polarized light is transmitted.

[0050] In a preferred embodiment of the first or third technical solution, at least one polarization compensation layer is provided upstream and / or downstream of the liquid crystal layer, thereby balancing the different polarization changes for light incident vertically on the one hand and light incident at an angle to the surface normal on the other hand.

[0051] Preferably, the preferred directions each make an angle between 0° and 45° with the surface normal of the first layer. Take for example a screen with such a switchable filter, which covers customary viewing angles.

[0052] For special applications, no matter which of the above technical solutions is adopted, the switchable filter can be divided into a plurality of individually switchable parts, so as to achieve local switchability between various possible working states. In cooperation with the image reproduction unit, this means that, for example, only a part of the image area can be switched between a private mode for privacy protection and a public mode without privacy protection (i.e., free viewing), while the complementary part of the image area is always in the privacy protection mode or the non-privacy protection mode. There can even be a plurality of such parts that are geometrically separated from each other and can be switched between working modes individually or collectively.

[0053] Furthermore, preferably, each of the layers of the first optical component and / or of the possibly present second optical component is constructed aperiodically. This reduces the occurrence of visual artifacts, such as Moire patterns, which may be offensive to a viewer of the corresponding screen.

[0054] The present invention acquires a particular significance by combining the above-mentioned switchable filter with an image reproduction unit to form a screen. In addition to the switchable filter as described above, such a screen further comprises: an image reproduction unit arranged downstream or upstream of the switchable filter from the viewer's perspective. The working mode of the above-mentioned switchable filter can be directly applied to the screen, so that the screen can also work in the various working modes mentioned above according to the design adopted by the switchable filter (for example, at least in the first working state for a free public viewing mode with an unlimited range of emission angles or viewing angles in the horizontal direction, and in a private viewing mode with a restricted range of emission angles or viewing angles in the horizontal direction compared to the free viewing mode), so that viewers outside this restricted viewing angle range can only perceive the image content presented on the screen in the free viewing mode.

[0055] Advantageously, the image reproduction unit corresponds to an LCD panel, one polarization filter of which corresponds to the polarization filter of the switchable filter. Furthermore, it can be a front polarizer or a back polarizer in the LCD structure. Furthermore, advantageously, the switchable filter can be arranged between the LCD panel and its backlight in order to switch between a first operating state in a free field of view mode and a second operating state in a restricted field of view mode, since due to the switchable filter, for example when switching to the horizontal direction, the light of the backlight is sometimes focused and sometimes not focused in the horizontal direction. Here, "focusing" does not mean focusing in the manner of a lens, but rather angularly reducing the emission range or transmission range.

[0056] The image reproduction unit can optionally be an OLED, a field emission display (SED), a field emission display (FED), a micro-LED display or a vacuum fluorescent display (VFD) with a switchable filter in front of it. Since the switchable filter acts independently of the type of image reproduction unit, any other type of screen is also conceivable.

[0057] Such a screen is advantageously used in mobile devices, cars, aircraft or ships, payment terminals or access systems, wherein it is possible to switch between the above-mentioned operating modes to protect sensitive data, i.e. to present the image content perceptibly only to one viewer or to present the image content to multiple viewers simultaneously.

[0058] In the following, the optical component according to the invention will be explained in more detail again and possible embodiments will be described, which optical component achieves the task and can be used in particular as the first and / or second optical component in the four above-mentioned technical embodiments of the switchable filter.

[0059] Such an optical component comprises: a first layer, or a first layer and a plurality of further layers, preferably more than five layers, wherein within the scope of the invention, each of the layers may correspond, for example, to a molecular layer, but may also be a respective mechanically separated layer of a suitable material. Each layer comprises: a material having a plurality of light-absorbing transition dipole moments. Possible materials have already been mentioned above in the description of the optical component of the switchable filter. Each transition dipole moment is oriented parallel to a selectable preferred direction or fluctuates around the preferred direction, at least in a first state, with a tolerance of a maximum of 10°, so that light incident on the optical component is transmitted or at least partially (to completely) absorbed depending on its direction of incidence relative to the layer and its polarization state. Preferably, the preferred directions each make an angle of between 0° and 45° with the surface normal of the first layer.

[0060] The quenching (i.e., absorption) of light is related to the absolute amount of transition dipole moments, and therefore necessarily to the thickness of the layer (in which the transition dipole moments are located), and to the orientation of the transition dipole moments and the polarization of the incident light relative to each other. The density and strength of the above-mentioned transition dipole moments or the refractive index of the layers of the optical component may vary depending on the specific implementation. If a passive (i.e., non-switching) optical component is used, the volume density of transition dipoles may be close to 100%.

[0061] For simplified transmission modeling, it is assumed that the transition dipole moment in the optical component is oriented parallel to the plane of incidence of the light on the optical component, and the preferred direction corresponds to the perpendicular bisector of the optical component. In addition, the plane of incidence does not refer to the surface of the optical component, but the plane in which the light wave propagates, wherein the surface of the optical component is at right angles to the plane of incidence. As a transverse wave, the light wave has a transverse magnetic oscillation component and a transverse electric oscillation component, which are perpendicular to each other and perpendicular to the propagation direction. When the light incident on the optical component, all the light waves are initially unpolarized, that is, the oscillation directions of the transverse electric component and the corresponding transverse magnetic component are statistically distributed. When reaching the surface of the optical component with such a transition dipole moment oriented perpendicular to the surface of the optical component, the light interacts with the transition dipole moment of the optical component or the material contained therein and becomes polarized. Among them, the oscillation component located in the plane of incidence is absorbed. That is, light polarized parallel to the plane of incidence (i.e., transverse magnetic polarization or p-polarization) is absorbed, while light polarized perpendicular to the plane of incidence (i.e., parallel to the surface of the optical component) (i.e., transverse electric polarization or s-polarization) is completely transmitted. Thus, unpolarized light that passes through an optical component not parallel to the transition dipole moment becomes at least partially s-polarized when passing through an optical component having a transition dipole moment oriented parallel to the plane of incidence of the light. If the preferred direction does not correspond to the perpendicular bisector, o-polarization (ordinary polarisation) is considered instead of s-polarization and e-polarization (extraordinary polarisation) is considered instead of p-polarization.

[0062] This characteristic is essential in all technical solutions of the present invention and constitutes the basic inventive means-effect relationship. In the following, the transmission of p-polarized light with an incident intensity of I0(α) is modeled. The transmission of light by the absorbing layer is described by the Lambert-Beer law:

[0063]

[0064] Here, α is the propagation direction relative to the surface normal, d(α) is the optical path length relative to the propagation direction, N is the number of absorbing molecules, and σ abs (α) is the absorption cross section related to the incident angle. With the help of Snell's refraction law, the propagation angle α in the medium can be calculated based on the incident angle β. Then, according to the equation of transition dipole moment and optical path, it is obtained:

[0065]

[0066] Depending on the application, individual layers are structured in a periodic or aperiodic manner, wherein a periodic structure is advantageous with regard to avoiding visual artifacts.

[0067] In a preferred embodiment, each transition dipole moment is oriented in a respective preferred direction within a tolerance of a maximum of 10° around the respective preferred direction. As a result, the highest transmittance also occurs in this preferred direction. It is also preferred that at least two such preferred directions in a selectable plane (usually one of the layers) differ by more than 10°. This makes it possible to define a plurality of preferred directions in one layer, which can all be directed to a point in space (e.g. the viewer), wherein different orientations can be achieved by suitable adjustment of the material properties in the layer, for example by photo-orientation. For this purpose, liquid crystals are combined with photoreactive substances. Incident polarized light simultaneously orients the molecules and triggers a photoreaction. By controlling the polarization, the orientation of the molecules can be influenced.

[0068] The micro-lambda filters described in the prior art (also called "ViewControlFilter-VCF" or "LightControlFilter-LCF") make use of geometrical optics. Due to the periodic alternation of transparent and absorbing layers, incident light propagating at large angles relative to a defined direction is almost completely absorbed. Here, the position of the absorber is controlled. In contrast, since the absorption cross section of the molecules changes with the propagation direction, the transmittance of light with different propagation directions changes in the optical component according to the invention. Therefore, in the present invention, the position of the absorber is not controlled, but rather the orientation (orientation) of the absorber is controlled. In other words, the present invention is based on the direction-dependent absorption of the light beam when passing through the optical component according to the invention and is essentially independent of the position of the light beam, with the exception of the preferred direction respectively specified for the transition dipole moment. This applies both to the non-switchable optical component according to the invention described above and to the switchable design described below.

[0069] For the switchability of the optical effect of the optical component according to the invention, i.e. for the switchable optical component, the transition dipole moment in each layer can change its orientation and / or its absolute value between a first state and at least one second state, so that the individual layers can be placed alternately in at least two different states. A possible design of the switchable optical component or each layer therein is, for example, based on liquid crystals, and / or dyes or dye mixtures, which can be arranged in a so-called "vertical alignment cell" or in a liquid crystal cell with uniform surface orientation, and wherein rotation between at least two states is possible. In addition, the light-absorbing transition dipole moment also rotates, so that at least two active states can be presented. In particular, in this technical solution, it is conceivable that more than two (for example, three or eight) states each having a different optical effect are obtained. Other liquid crystal cell designs are also conceivable. For this purpose, in particular, an electric field is used to rotate the liquid crystal. In which, for example, the field-free state can be described by the first electric field or the second electric field, while the other electric field has an absolute field strength greater than zero (for example 0.5 MV / m).

[0070] Therein, the first state corresponds to the above-mentioned condition, and at least one second state differs in having at least one other preferred direction.

[0071] In such an active, i.e. switchable optical component, it is conceivable that the volume density of the transition dipole moment based on the liquid crystal is between 0.1% and 90%. Alternatively, the concept of the switchable optical component or each layer therein can be conceived that the transition dipole moment is placed in a liquid in an electrowetting process. In this way, in particular, the density of the transition dipole moment is changed, but not limited to this.

[0072] Furthermore, the optical component can also be divided into a plurality of individually switchable parts in order to achieve a local switch between at least two different states. In this way, within the scope of the switchability with at least two states, it can be achieved in particular that the local transmission maxima between the at least two states are located in respective different directions.

[0073] Furthermore, preferably, the respective preferred direction of the transition dipole moment can be selected according to the position of the transition dipole moment in the respective layer.

[0074] In another preferred embodiment of the optical component, each layer is divided into different zones along a selectable reference line of the respective layer, wherein for each zone a zone preferred direction is selectable, which zone preferred direction applies to all transition dipole moments of the respective layer located in the zone, wherein all zone preferred directions differ from one another in pairs and point in the direction of the viewer with a tolerance of a maximum of + / -10°. Thus, within a layer and within each zone applicable thereto, all transition dipole moments are parallel to the preferred direction applicable therein with a tolerance of a maximum of + / -10°. Advantageously, each of the layers is constructed non-periodically in structure, so that the occurrence of disturbing visual artifacts is reduced or avoided. This arrangement has the advantage that in a restricted field of view mode, the viewer perceives the screen as being uniformly illuminated. Since the luminous density is dependent on the viewing angle, the viewer perceives the screen as being non-uniform when the orientation of the transition dipole moments is constant over the entire surface of the filter.

[0075] A simple method of manufacturing an optical component according to the present invention as described above is that the optical component is formed by laminating a plurality of polymer thin film polarizers. In this case, the optical component is constituted as a laminate of multiple polymer thin film polarizers. As an alternative or in combination, the optical component can also be made by photo-aligning molecules or particles.

[0076] Preferably, the material of the optical component comprises at least one dye, preferably a dichroic dye mixture. The at least one dye consists of dye molecules, wherein advantageously a transition dipole or a transition dipole moment is associated with each dye molecule, i.e. each dye molecule corresponds to a transition dipole or a transition dipole moment. Typically, in an LC dye mixture, the mass fraction of the dye in the material of the individual layers is, for example, 0.01% to 10%, preferably 0.1% to 5%. The thickness of the layer is preferably in the range of 0.2 μm to 50 μm, preferably in the range of 0.5 μm to 20 μm, all limit values ​​being respectively included. The dyes or dye mixtures of different layers may be different.

[0077] Furthermore, the material of the optical component may contain liquid crystals and / or be mixed with liquid crystals. In the case where a plurality of layers are present, this may also vary from layer to layer.

[0078] As a preferred embodiment, for each layer, a mixture of liquid crystals with at least one dye, in particular with at least one dichroic dye mixture is suitable. Suitable dichroic dyes or dye mixtures include, for example, azomethine dyes, indigo and thioindigo dyes, merocyanine, azulene, quinolinone dyes, perylene dyes, phthalocyanine dyes, dimethicone dyes, phthalocyanine ... Dioxazinfarbstoffe, Triphenylmethane Triphenodioxazinfarbstoffe, quinine In some embodiments, the present invention relates to a liquid crystal dye mixture, wherein the liquid crystal dye mixture comprises a phthalocyanine dye, a triazine dye, a tartrazine dye, an azo dye and an anthraquinone dye. The production of liquid crystal dye mixtures is described, for example, in US Pat. No. 4,695,131 A. In addition, the surface of the outer sealing layer is preferably treated, for example by drawing, in order to achieve a uniform surface orientation of the transition dipole moment or any liquid crystal present.

[0079] In particular, when used for switchable filters, generally, a polarization filter can advantageously be located before or after the optical component in the viewing direction. The polarization filter helps to determine or analyze the polarization properties of light passing through the optical component, and preferably, the polarization filter should always be present. In this case, the maximum transmission of the optical component is usually always in a direction parallel to the polarization direction of the polarization filter. There can also be two such polarization filters arranged before and after the optical component in the viewing direction, respectively, and the two such polarization filters are oriented substantially parallel to each other with respect to their linear polarization directions, whereby the protective effect in the restrictive field of view mode can be improved.

[0080] Therefore, the present invention also includes an illumination device having the above-mentioned optical component. Such an illumination device can operate in at least two operating modes: an operating mode B1 for a free view mode, and an operating mode B2 for a restricted view mode. The difference between the restricted view mode and the free view mode is that the light is emitted in the direction of the viewer within a restricted angle range compared to the free view mode. Viewers outside the restricted angle range cannot see the light emitted by the illumination device, and the same applies to the screen, which will be explained below, while in the free view mode, as long as the viewer is within the emission angle range that is basically naturally restricted by the illumination device or the screen in the free view mode, and the emission angle range is significantly larger than the emission angle range in the restricted view mode, the viewer can perceive the light emitted by the illumination device or the screen. Wherein, the restriction may occur in multiple spatial directions, such as upward, downward, right and / or left, depending on the specific application.

[0081] The lighting device comprises: a backlight extending in a plane, which contains the optical components as described in detail above and emits light. The lighting device comprises: a plate-shaped light guide, which is arranged in front of the backlight in the viewing direction, and has a decoupling component (Auskoppelelement) in at least one of the large surfaces and / or in its volume, wherein the light guide is transparent for at least 40%, preferably at least 70% of the light emitted from the backlight. A light-emitting component is arranged laterally on at least one narrow side of the light guide. In addition, in the viewing direction, a linear polarization filter is arranged in front of the backlight or in front of the light guide, whereby the light emitted from the backlight and passing through the polarization filter is limited in its propagation direction. In operating mode B2, the backlight is turned on and the light-emitting component is turned off. In operating mode B1, at least the light-emitting component is turned on, that is, in operating mode B1, it does not matter whether the backlight is turned on or off.

[0082] Finally, as mentioned above, the above optical assembly can also be used for a screen, which can operate in at least two operating modes mentioned above in conjunction with the lighting device, namely, operating mode B1 for free field of view mode and operating mode B2 for restricted field of view mode. Such a screen comprises: a backlight extending in a planar shape, which contains the above optical assembly and emits light. The screen also comprises: a plate-shaped light guide, which is arranged in front of the backlight in the viewing direction and has a decoupling component in at least one of the large surfaces and / or in its volume, wherein the light guide is transparent for at least 40%, preferably at least 70% of the light emitted from the backlight. A light-emitting member is arranged laterally on at least one narrow side of the light guide. In addition, in the viewing direction, a linear polarization filter is arranged in front of the backlight or in front of the light guide, whereby the light emitted from the backlight and passing through the polarization filter is limited in its propagation direction. In addition, in the viewing direction, a transmissive image reproduction device is arranged in front of the light guide. The polarization filter may be arranged in the image reproduction device and in particular may be part of the image reproduction device (as is the case, for example, in an LC display). In operating mode B2, the backlight is switched on and the light emitting means are switched off. In operating mode B1, at least the light emitting means are switched on, i.e., in operating mode B1, it is not important whether the backlight is switched on or off.

[0083] More generally, the invention also comprises a screen comprising at least one optical component as described above or a configuration as described above, and an image reproduction unit arranged downstream or upstream of the optical component from the viewer's perspective. Advantageously, the image reproduction unit corresponds to an LCD panel, and one polarization filter of the LCD panel corresponds to the aforementioned polarization filter. In addition, it can be a front polarizer or a back polarizer in the LCD structure. The image reproduction unit can optionally be an OLED, a field emission display (SED), a field emission display (FED), a micro-LED display or a vacuum fluorescent display (VFD) with an optical component in front of it. Since the optical component does not act depending on the type of image reproduction unit, any other type of screen can also be considered. Such a screen is advantageously used in mobile devices, cars, aircraft or ships, payment terminals or access systems. Therein, in the case of a switchable optical component, it is possible to switch between the above-mentioned operating modes to protect sensitive data, that is, to present the image content to only one viewer perceptibly, or to present the image content to multiple viewers simultaneously. In addition, the switchable optical component or non-switchable optical component using the above technical solution can be used with a static image or a dynamic image reproduction unit such as an LCD panel, so as to make the advertising content visible only within a restricted visual range.

[0084] If the above parameters are changed within certain limits, the performance of the present invention can be maintained in principle.

[0085] It is understood that the above-mentioned features and the features yet to be explained below can be used not only in the combination specified but also in other combinations or alone without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Below, the present invention will be explained in more detail by way of embodiments and with reference to the accompanying drawings, which also disclose important features of the present invention. The embodiments are for illustrative purposes only and should not be construed as restrictive. For example, the description of an embodiment having multiple components or assemblies should not be construed as all components or assemblies being necessary for implementation. On the contrary, other embodiments may also include alternative components and elements, fewer components and elements, or additional components and elements. Unless otherwise stated, components and elements of different embodiments may be combined with each other. Modifications and variations described for one of the embodiments may also be applied to other embodiments. In order to avoid repetition, the same or corresponding components in different figures are identified with the same symbols and are not explained multiple times. Among them:

[0087] Figure 1a This is a schematic diagram of the principle of a non-switching optical component.

[0088] Figure 1b is a schematic diagram of a switchable optical component in a first state,

[0089] Figure 1c For the second state, Figure 1b Schematic diagram of the switchable optical components in

[0090] Figure 2a The schematic diagram of other optical components is shown below.

[0091] Figure 2b is a schematic diagram of a section of another switchable optical component in a first position,

[0092] Figure 2c is a schematic diagram of a section of the other switchable optical component in a second position,

[0093] Figure 3 To have basis Figure 1b and Figure 1c as well as Figure 2b and Figure 2c A schematic diagram of the structure of the switchable optical component,

[0094] Figure 4 To be based on Figure 2a-2c , which is an exemplary diagram comparing the measured transmission behavior of an optical component at different angles with the measured transmission behavior of a thin-film filter in the prior art at different angles,

[0095] Figure 5is a schematic diagram of the principle of a switchable filter with a polarization filter in the third technical solution,

[0096] Figure 6 is a schematic diagram of the principle of a switchable filter without a polarization filter in the third technical solution,

[0097] Figure 7a-7c Based on Figure 6 A simplified diagram of the light affected by the switchable filter,

[0098] Figure 8 is a schematic diagram of the principle of the switchable filter in the fourth technical solution,

[0099] Fig. 9 is a schematic diagram of the principle of the switchable filter in the first technical solution,

[0100] Fig.10 is a schematic diagram of the principle of the switchable filter in the second technical solution, and

[0101] Figures 11 to 15 An optical simulation used to illustrate the optical effects of optical components. DETAILED DESCRIPTION

[0102] The drawings are not drawn to scale and are schematic only.

[0103] Figure 1a A simplified schematic diagram of an exemplary non-switching optical component 1 is shown. The optical component comprises at least one layer S1, wherein the layer S1 comprises: a material having a plurality of photo-absorbing photo-transition dipole moments (here simply illustrated as small vertical lines), the photo-absorbing photo-transition dipole moments being oriented parallel to a selectable preferred direction (here, perpendicular to the surface of the layer S1) or fluctuating around the preferred direction at least in a first state, whereby the preferred direction comprises an angle between 0° and 45° with respect to the surface normal of the layer S1, so that light incident on the optical component is transmitted or partially or completely absorbed depending on its incident direction relative to the layer S1 and its polarization characteristics.

[0104] The optical component 1 can be made, for example, by laminating a plurality of polymer thin film polarizers and / or by photo-aligning molecules or particles. The density of the above-mentioned electrical transition dipoles in layer S1 can vary depending on the implementation. If a passive polarizer is used, the volume density can be close to 100%.

[0105] The material of the optical component 1 comprising the transition dipole moment may also comprise at least one dye, in particular a dye molecule, preferably at least one dichroic dye or a dichroic dye mixture. Furthermore, advantageously, the dye molecule may correspond to the transition dipole moment. Typically, the dye accounts for 0.01% to 30% by mass in the material of each layer S1, S2, ..., preferably 0.1% to 15% or 5%, or 0.01% to 10%. The thickness of the layer is preferably in the range of 0.2 μm to 50 μm, preferably in the range of 0.5 μm to 20 μm. The dyes or dye mixtures of different layers may be different.

[0106] The layers S1, S2, ... comprising transition dipole moments may also comprise liquid crystals or polymers and / or may be mixed with liquid crystals. Preferably, the layers S1, S2, ... comprise: a mixture of liquid crystals or polymers with at least one dye, in particular, with at least one dichroic dye.

[0107] The optical component 1 provides a privacy filter for linearly polarized light. Therefore, a polarization filter P is provided here, which polarizes light incident from below linearly parallel to the drawing surface. However, the polarization filter P does not change the propagation direction of the light. The two thick arrows indicate two possible propagation directions of the light. Due to the effect of the transition dipole moment, light with a (tilted) direction of, for example, more than about 30° relative to the preferred direction (here the perpendicular bisector of the layer S1) is absorbed by the optical component 1. Finally, as shown by the single arrow in the upper part of the figure, substantially only the light incident along the preferred direction or, here, perpendicular to the optical component 1, still exists after passing through the optical component. Depending on the application, each of the layers S1, S2, ... is constructed periodically or aperiodically in structure.

[0108] The quenching (i.e. absorption) of light is related to the absolute amount of transition dipole moments and therefore necessarily to the layer thickness of the material having transition dipole moments. The density and strength of the above mentioned transition dipole moments or the refractive index in the layers S1, S2, ... may vary depending on the implementation. If a passive (i.e. non-switching) optical component 1 is used, the volume density of transition dipoles may be close to 100%.

[0109] to this end, Figures 11 to 15 An optical simulation is shown for explaining the optical effect of the optical component 1 . Fig.11 A diagram showing the normalized transmission of light through the optical component 1 according to FIG. 1 is shown, here plotted over horizontal measuring angles of -90° to +90°. For angles above + / -25°, strong absorption effects are clearly visible. The simulation is based on the assumption that the optical component 1 has a layer thickness of d=0.5 mm, a material refractive index n=1.5, a molar concentration M=0.01 mol m -3 and an exemplary molar extinction ratio ε = 12700 m 2 mol -1The thickness and the concentration can be varied in proportion to each other, so that, for example, the same transmittance can be obtained with a thickness ten times smaller and a concentration ten times higher. Fig.12 In the example, for the value range that is important for use, the Fig.11 The relationship between the transmittance and the transmittance is plotted in logarithmic form on the vertical axis. It can be seen that under this parameter, at + / -25°, the transmittance has dropped to about 1%, and at + / -40°, the transmittance has been reduced to only about 0.001%. Fig.13 In the equation, regarding the refractive index n, Fig.11 The assumed conditions were calculated for the values ​​n=1.0; 1.3; 1.5 and n=1.7. It can be seen that the lower the refractive index of the material of layer S1, the more limited the transmission (Transmission im Winkel) at the angle. In addition, Fig.14 The thickness of the optical component 1 is shown in FIG. Fig.11 The change in the normalized transmittance of the optical component 1 with respect to . In this case, layer thicknesses of d = 0.1 mm; 0.2 mm; 0.3 mm; 0.4 mm and 0.5 mm were calculated. As expected, a greater layer thickness thus results in a stronger restriction of the transmittance at the above angles. Finally, Fig.15 The angle-dependent, normalized transmittance is shown for three selected parameter sets (1. n = 1.0 and d = 0.2 mm; 2. n = 1.5 and d = 0.5 mm; 3. n = 1.7 and d = 0.65 mm). The three parameter sets produce very similar optical effects.

[0110] In contrast, the micro-laminated filters known from the prior art (also called "View Control Filter-VCF" or "Light Control Filter-LCF") make use of geometrical optics. Due to the periodic alternation of transparent and absorbing layers, light propagating at large angles relative to a defined direction is (almost) completely absorbed. The position of the absorber is controlled. In contrast, since the absorption cross section of the molecules varies with the propagation direction, the transmittance of light with different propagation directions in the optical component 1 varies. Therefore, the position of the absorber is not controlled, but rather, in particular, the orientation of the absorber is controlled. In other words, the effect of the optical component 1 is based on the direction-dependent absorption of the light beam when passing through the optical component and is essentially independent of the beam position. This applies both to the non-switchable optical components described above and to the switchable designs described below.

[0111] For the switchability of the optical effect of the optical component 1, that is, for the switchable optical component 1, the photo-absorbing photo-transition dipole moment in each layer S1, S2, ... can change its orientation and / or its absolute value, so that each layer S1, S2, ... can be placed in at least two different states. A possible design of the switchable optical component 1 or each layer S1, S2, ... therein is based, for example, on liquid crystals or phosphors, which can be arranged in a so-called "vertical alignment cell" or in a liquid crystal cell with uniform surface orientation, and wherein it can be rotated between at least two states. Therefore, the photo-absorbing photo-transition dipole moment also rotates and can present at least two active states. In particular, in this technical solution, it is conceivable to obtain more than two states (for example, three or eight states), each having a different optical effect. Other liquid crystal cell designs are also conceivable.

[0112] to this end, Figure 1b a schematic diagram showing a switchable optical component in a first state, Figure 1c A schematic diagram showing a switchable optical component in a second state.

[0113] For this example it is assumed that the incident light is p-polarized, i.e., polarized parallel to the plane of incidence (see Figure 1b ). If the transparent electrodes E1, E2 are uncharged, i.e., they generate an electric field EF1 with 0 V / m (no electric field), the liquid crystal molecules and dye molecules (here, for example, constructed as layers S1, S2 and S3), which are illustrated here as dots, are oriented along the surface of the electrodes E1, E2. This can be achieved by a suitable combination of surface functionalization and liquid crystals and is known in the prior art. For light propagating in the drawing plane and being s-polarized, the polarization of the light and the transition dipole moment of the liquid crystal are always oriented perpendicularly to each other. Therefore, no absorption occurs, and therefore, the propagation direction of the light with s-polarization illustrated above and below the substrate S will pass through the switchable optical component 1 without hindrance.

[0114] like Figure 1c As shown, if electrodes E1 and E2 are charged, that is, they generate an electric field with EF2>0 V / m, the liquid crystal rotates in layers S1, S2 and S3. When the voltage and field strength EF2 exceed a certain threshold, the liquid crystal molecules and (if present) the dye molecules are oriented almost parallel to the field lines of the electric field EF2. As a result, light is absorbed according to the angle α (the angle between the propagation direction of the light and the normal to the surface of layer S1). The absorption rate increases with increasing angle α. The blanking of the electric field of light is proportional to sin(α). In principle, it is advantageous to control the orientation of the dye molecules in order to thereby control the anti-peeping axis or to exert a defined light influence. In accordance with Figure 1b In the state, the transition dipole moment is perpendicular to the polarization of the incident light. Figure 1cIn the state of the switchable optical component, the light is parallel to the vertical light incidence. It is conceivable that the volume density of the liquid crystal-based dye is between 0.1% and 20%, if necessary up to 90%.

[0115] Figure 2a The schematic diagram of another non-switching optical component 1 is shown. The optical component comprises (here for example only one) layer S1, wherein the layer S1 comprises: a plurality of light-absorbing transition dipole moments (composed of Figure 2a The optical component 1 is a material of the optical component 1 (represented by a short line in the middle layer S1). Each transition dipole moment is oriented parallel to a respective preferred direction (represented here by a thick arrow) or fluctuates around the respective preferred direction with a tolerance of up to 10° at least in a first state, and the preferred direction can be selected for the transition dipole according to the position of such transition dipole in the layer S1, wherein at least two such preferred directions differ by more than 10° in a selectable plane (here the drawing plane). This allows light incident on the optical component 1 to be transmitted or partially or completely absorbed according to its incident direction relative to the layer S1 and its polarization properties, wherein the highest transmittance of each transition dipole exists in the preferred direction respectively selected for its position in the layer S1, wherein a tolerance of up to 10° is allowed.

[0116] Compared to FIG. 1 , the optical component 1 shown in FIG. 2 is designed such that the layer S1 is divided along a selectable reference line (here the bottom edge of the layer) into different areas A1, A2, A3, A4, A5, wherein for each area A1, A2, ... a dedicated area preferred direction is selected (see thick arrow), which applies to all transition dipole moments of the layer S1 located in an area A1, A2, ... In addition, all area preferred directions are different from one another in pairs and all area preferred directions point in the direction of the viewer 6 with a tolerance of maximum + / -10°. Therefore, in the layer S1 and in each applicable area A1, A2, ..., all transition dipole moments are parallel to the area preferred direction applicable here with a tolerance of maximum + / -10°. Due to the definable transmittance of the optical component 1, the optical component can be used particularly advantageously to create a privacy protection solution.

[0117] In order to enable the switchability of the optical effect of the optical component 1, that is, to enable a switchable optical component 1, the light-absorbing transition dipole moment in each layer S1, S2, ... can change its orientation (orientation) and / or its absolute value and / or its density, so that each layer S1, S2, ... can be placed in at least two different states.

[0118] to this end, Figure 2b The first section of the switchable optical component is shown in the first state (corresponding to Figure 2a A1) in the schematic diagram, Figure 2c The second section of the switchable optical component in the first state (corresponding to Figure 2a A5 in FIG. 1 shows a schematic diagram of the principle of the substrate S. Here, three layers S1, S2, S3 are present by way of example. The liquid crystal mixed with the dichroic dye mixture is represented by the elliptical elements in the layers S1, S2, S3, wherein the black elliptical elements represent dye molecules in a highly simplified manner and the white elliptical elements represent liquid crystals in a highly simplified manner. The inclination of the ellipse further indicates the spatial orientation. The substrate S can be glass or a polymer or other transparent material.

[0119] The respective transparent electrodes E1, E2, for example indium tin oxide layers (ITO layers), are used to control the orientation of the liquid crystal mixed with the dye mixture. However, different orientations of the liquid crystal molecules and the dye are preferably achieved by different surface functionalizations. Mechanical and optical methods can be considered here. Figure 2b The orientation of the liquid crystal together with the dye mixture shown is approximately equivalent to that according to Figure 2a Orientation of the preferred direction of the middle segment A1. Figure 2c The orientation of the liquid crystal together with the dye mixture shown is approximately equivalent to that according to Figure 2a The preferred direction of the middle segment A5 is oriented. Figure 2b In the case of , light incident on the optical component 1 from below is transmitted to the greatest extent in the respective preferred direction of the transition dipole; in other directions it is partially or completely absorbed. This also applies in a similar manner to Figure 2c situation.

[0120] Regarding the behavior of p-polarized light and s-polarized light incident on an optical component when electric fields EF1 and EF2 are applied, refer to Figure 1b and Figure 1c The detailed description of , which applies analogously here, except that the transition dipole moment is oriented differently and in the medium predominantly o-polarization instead of s-polarization and e-polarization instead of p-polarization.

[0121] Figure 3 Shown according to Figure 1b and Figure 1c as well as Figure 2b and Figure 2cSchematic diagram of the structure of a switchable optical component 1 according to an embodiment of the present invention. Here, two linear polarization filters P are present on the outer surface, one of which is optional, wherein the polarization directions of the linear polarization filters are substantially parallel to each other (i.e., without taking into account a tolerance of a few degrees). A transparent substrate S is provided on the respective inner side (i.e., on the opposite side of the polarization filter P), and electrodes E1 and E2 are provided on the inner side of the substrate. From this, the orientation layer 4 facing inwards serves for the orientation of the liquid crystal, which is mixed with at least one dichroic dye to form the inner layers S1, S2, ... . Here, the transition dipole moment is formed by the at least one dichroic dye. In principle, in the structure of the optical component 1 in all the described variants, additional retardation films can also be used to be able to further adjust the polarization state.

[0122] The square wave voltage applied between electrodes E1 and E2 preferably has an effective value between 0 V and 20 V. The alignment layer 4 is, for example, a treated surface (e.g. brushed glass or polymer) to achieve a uniform surface alignment of the transition dipole moment or liquid crystal. Figure 2b and Figure 2c Status shown.

[0123] at last, Figure 4 According to Figure 2 and Figure 3 An exemplary view of the normalized transmission behavior of the optical component 1 (solid line) measured at different angles compared with the normalized transmission behavior of the thin-film filter in the prior art (dashed line) measured at different angles. The horizontal axis is the respective measurement angle and the vertical axis is the normalized transmittance. For the transmission behavior of the exemplary optical component 1, a so-called "top-hat" distribution can be observed in the continuous curve, that is, the transmittance is stably maintained at at least 80% in a wide angle range of about -17° to +17°. Here, the half-value width is about 40° in total. Therefore, a viewing angle change of ±15° provides a good transmission uniformity that the viewer 6 feels, thereby achieving a good uniformity when lighting or image reproduction under the cooperation of the image reproduction unit). In comparison, the exemplary thin-film filter in the prior art (whose normalized transmission behavior is illustrated in dashed form in Figure 4 ), in contrast, has a reduced half-value width of only about 35°, furthermore, does not have a distribution approximating a "top hat" and also has poorer privacy protection in the angular ranges of -30° to -25° and +25° to +30°, the reason being that the transmittance in this angular range is greater than that of the optical component 1.

[0124] The optical component is particularly applicable to a switchable optical filter 5 . Figure 5A third technical solution of such a switchable filter 5 is shown, and in order to be consistent with the general description of the present invention, the name "third" is selected before "first" and "second". It includes a first optical component 1 and a second optical component 2. The two optical components 1 and 2 are themselves non-switchable, that is, static. The preferred directions of the transition dipole moments of the two optical components differ from each other by less than 40°, preferably less than 20°, and particularly preferably less than 10°, wherein the first preferred direction of the first optical component 1 and the second preferred direction of the second optical component 2 are selectable. In this case, the two preferred directions are exemplarily parallel to each other and correspond to the perpendicular bisector of the switchable filter 5 located in the drawing plane. A switchable liquid crystal layer 3 is provided between the optical components 1 and 2, and the switchable liquid crystal layer exerts or does not exert an influence on the polarization characteristics of the light passing through the switchable liquid crystal layer according to one of the electric fields EF1 and EF2 acting on the switchable liquid crystal layer. In the figure, from the perspective of the viewer 6, a polarization filter P is disposed below the optical components 1 and 2; the polarization filter can also be disposed above the optical components 1 and 2. Not shown in the figure: components for selectively generating the first electric field EF1 and the second electric field EF2, for example, electrodes disposed above and below the liquid crystal layer 3.

[0125] In the first operating mode B1 with the first electric field EF1 applied and having the first sub-operating mode B1H and the second sub-operating mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter 5 parallel to the first preferred direction or the second preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter 5 at an angle of more than 30° to the corresponding preferred direction is absorbed, wherein the absorption occurs only in the first direction in the first sub-operating mode B1H and only in the second direction perpendicular to the first direction in the second sub-operating mode B1V, wherein the first direction or the second direction is perpendicular to the polarization direction of the polarization filter P. When applied to a screen, the first direction may correspond to the horizontal direction and the second direction may correspond to the vertical direction, wherein "horizontal" refers to a line parallel to the distance line between the viewer's eyes. In this case, the horizontal line is, for example, parallel to the bottom edge of the layer S1 or the screen, and the vertical line is parallel to the left side or the right side.

[0126] In the second operating mode B2 with the second electric field EF2 applied, on the one hand, at least 24% of the non-polarized light incident on the switchable filter 5 parallel to the first preferred direction or the second preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter 5 at an angle of more than 30° to the corresponding preferred direction is absorbed.

[0127] Figure 6 A variant of the third embodiment of the switchable filter 5 without the polarization filter P is shown in FIG. The behavior of this variant in the operating mode B2 is similar to that of the reference Figure 5The described behavior of the switchable filter 5 is the same, but in the first operating mode B1 with the first electric field EF1 applied, at least 24% of the unpolarized light incident on the switchable filter (5) at any angle is transmitted.

[0128] Therefore, the switchable filter 5 of the third technical solution, in cooperation with the image reproduction unit, allows switching between two-sided anti-peeping protection and four-sided anti-peeping protection (for example, up / down protection B1V and up / down / left / right protection B2) when a polarizing filter P is present, or, when the polarizing filter P is not present, allows switching between omnidirectional free viewing and four-sided anti-peeping protection (for example, free viewing B1 and up / down / left / right protection B2).

[0129] The no-electric-field state may be described, for example, by an electric field EF1 or an electric field EF2, and each of the other electric fields EF2 or EF1 has an absolute field strength greater than zero (e.g., 0.5 MV / m). Therefore, depending on the design of the optical components 1 and 2, the no-electric-field state may mean that the operating mode B2 exists. However, the operating mode B1 may also exist in the no-electric-field state, including one of the sub-operating modes B1H, B1V if a polarization filter P is present.

[0130] Figures 7a to 7c Shown due to Figure 6 Schematic diagram of the polarization states of light generated by a switchable filter. Figure 7a The polarization states of the common modes are shown, corresponding to the operating mode B1 with a non-limiting viewing angle range, in which light with a viewing angle greater than 30° is tangentially polarized and light incident perpendicularly is linearly polarized. The preferred directions correspond to the respective perpendicular midlines. Figure 7c The polarization state in the restricted field of view mode is shown. Here, light with an incident angle of, for example, greater than 30° is strongly attenuated, while vertically incident light is transmitted without changing the polarization state.

[0131] The orientation or alignment of the transition dipole moment causes the light to be polar polarized at the angle of incidence, i.e. the linear polarization of the light is always perpendicular to the origin in the viewing space, which in this case is the perpendicular bisector. This state is shown in Figure 7a and applies to light after it has passed through the non-switching optical component 1. Light with a small angle is only weakly polarized. Ideally, vertically incident light is not absorbed, i.e. the polarization state remains unchanged.

[0132] At this time, if light enters the liquid crystal layer 3 from the optical component 2, whether the polarization state of the light changes and how it changes or remains unchanged depends on the state of the liquid crystal layer 3. For example, if the polarization rotation in the liquid crystal layer 3 is turned off in the no-electric-field state EF1, the above state does not change. After passing through the liquid crystal layer 3 and further passing through the non-switching optical component 1, the transmittance remains substantially unchanged. If there is a polarization filter P above the optical component 1 or below the optical component 2, one of the sub-operation modes B1H or B1V is realized according to the design. If there is no such polarizer, the operation mode B1 is realized.

[0133] In contrast, if the polarization rotation in the liquid crystal layer 3 is turned on, for example by applying an electric field EF2>0 V / m, the polarization is rotated by 90° everywhere. Figure 7b Middle: Here the polarization state after passing through the optical component 2 and the polarization-rotated liquid crystal layer 3 is shown. Therefore, in case of further light propagation, all light propagating at an angle greater than 25° or about 30° is blanked by the optical component 1. This corresponds to operating mode B2.

[0134] Figure 8 The schematic diagram of the switchable filter 5 in the fourth technical solution is shown. The switchable filter 5 includes two switchable optical components 1 and 2, wherein each of the two optical components includes: a first layer S1, or a first layer S1 and a plurality of other layers S2, .... Similar to the optical components of the third technical solution, each of the layers S1, S2, ... includes: a material having a plurality of light-absorbing transition dipole moments, wherein each transition dipole moment is oriented parallel to a first preferred direction selectable for the first optical component 1 and a second preferred direction selectable for the second optical component 2 with a tolerance of up to 10° or fluctuates around the preferred direction, at least in the first state, so that the light incident on the first or second optical component 1, 2 is transmitted or at least partially absorbed according to its incident direction relative to the layers S1, S2, ... and its polarization state.

[0135] However, unlike the third technical solution, the optical components 1 and 2 are switchable here, that is, the transition dipole moment of each of the layers S1, S2, ... can change its orientation and / or its value between a first state and at least one second state, so that each layer S1, S2, ... is alternately placed in at least two different states. In this technical solution, the switchable filter 5 includes: a component for selectively generating a first electric field EF1 or a second electric field EF2, wherein, for each of the two optical components 1 and 2, the first state is generated by applying the first electric field EF1, and the second state is generated by applying the second electric field. In an embodiment according to the fourth technical solution, the first electric field EF1 is applied to the first optical component 1, and the second electric field EF2 is applied to the second optical component 2.

[0136] Optionally, a polarization filter may be arranged above or below the optical component 1 combined into one unit. This is not necessary, but can improve the performance of the switchable filter 5. The polarization of the polarization filter P and the polarization of the incident light must be completely consistent. An optical anisotropic layer 7 is provided between the two optical components 1 and 2 for rotating the polarization direction of the light passing through the optical anisotropic layer 7 by 90°. The optical anisotropic layer 7 may be, for example, a layer with liquid crystal or a half-wave plate. The means for generating the two electric fields EF1 and EF2 are not shown in the figure.

[0137] When a first electric field EF1 is applied in the first operating mode B1 for the free field mode, at least 24% of the non-polarized light incident on the switchable filter 5 at any angle is transmitted, wherein, in the first operating mode B1, the transition dipole moments of the two optical components 1 and 2 are oriented perpendicular to each other, and if a polarization filter P is present, the polarization filter transition dipole component of the polarization filter P is oriented parallel to the transition dipole moment of the switchable optical components 1 and 2 closest to the polarization filter P.

[0138] When the second electric field EF2 is applied in the second operating mode B2 for the restricted field of view mode, on the one hand, at least 24% of the non-polarized light incident on the switchable filter 5 parallel to the first preferred direction or the second preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter 5 at an angle of more than 30° to the corresponding preferred direction is absorbed, wherein, in the operating mode B2, the transition dipole moment of the polarization filter P (if present) and the transition dipole moments of the switchable optical components 1 and 2 closest to the polarization filter P are oriented perpendicular to each other, and the transition dipole moments of the two optical components 1 and 2 are oriented parallel to each other. Here, preferably, the preferred direction also corresponds to the transition dipole moment of the switchable optical components 1 and 2 in the operating mode B2. Figure 8 The perpendicular bisector of the switchable filter 5 located in the drawing plane. As described above in conjunction with the third technical solution, this applies to the corresponding orientation of the switchable filter 5, in particular, when the horizontal direction is parallel to the bottom edge of the layer S1 and the vertical direction is parallel to the left or right edge of the layer, and applies to both the horizontal direction and the vertical direction.

[0139] Therefore, the switchable filter 5 of the fourth technical solution, in cooperation with the image reproduction unit, allows switching between omnidirectional free viewing and four-sided anti-peep protection (free viewing B1 and up / down / left / right protection B2).

[0140] Fig. 9The first technical solution of the switchable filter 5 is shown as a schematic diagram in principle. The first technical solution comprises a non-switchable first optical component 1, which also comprises: a first layer S1, or a first layer S1 and a plurality of other layers S2, ..., wherein each layer S1, S2, ... comprises: a material having a plurality of light-absorbing transition dipole moments. Each transition dipole moment is oriented parallel to a first preferred direction selectable for the first optical component 1 or fluctuates around the preferred direction with a tolerance of up to 10°, at least in a first state, so that light incident on the first optical component 1 is transmitted or at least partially absorbed according to its incident direction relative to the layers S1, S2, ... and its polarization state.

[0141] A polarization filter P is provided upstream or downstream of the first optical component 1. The figure still does not show a component for selectively generating the first electric field EF1 or the second electric field EF2. A liquid crystal layer 3 is provided between the first optical component 1 and the polarization filter P, and the first electric field EF1 or the second electric field EF2 acts on the liquid crystal layer, and the liquid crystal layer affects the polarization state of light passing through the liquid crystal layer according to the first electric field EF1 or the second electric field EF2.

[0142] In this first technical solution, in the first working mode B1 with the first electric field EF1 applied and having the first sub-working mode B1H and the second sub-working mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter 5 parallel to the first preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter 5 at an angle of more than 30° to the first preferred direction is absorbed, wherein the absorption occurs only in the first direction in the first sub-working mode B1H, and only in the second direction perpendicular to the first direction in the second sub-working mode B1V. In addition, preferably, the first preferred direction is still parallel to the perpendicular bisector of the switchable filter 5 in the drawing plane. With regard to the positions of the first and second directions, the implementation scheme proposed in relation to the third technical solution can be similarly applied.

[0143] In the second working mode B2 to which the second electric field EF2 is applied and which has a first sub-working mode B1H and a second sub-working mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter 5 parallel to the first preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter 5 at an angle of more than 30° to the first preferred direction is absorbed, wherein this absorption occurs only in the second direction in the first sub-working mode B1H and only in the second direction perpendicular to the first direction in the second sub-working mode B1V, and therefore, the absorption directions of each of the two sub-working modes B1H and B1V differ by 90° for the first working mode B1 and the second working mode B2.

[0144] Unlike before, here, both operating modes are operating modes of the restricted field of view mode, wherein the privacy protection can be switched between two mutually perpendicular directions (e.g., horizontal direction and vertical direction). The configuration of the first technical solution of the switchable filter 5 can be switched between the sub-operating modes B1V and B1H by rotating the polarization filter P by 90°.

[0145] Here, the no-electric-field state can also be described, for example, by the first electric field EF1 or the second electric field EF2, while the other electric field EF2 or EF1 has an absolute field strength greater than zero (e.g., 0.5 MV / m). Therefore, depending on the design of the optical component 1 and the polarization filter P, the no-electric-field state may mean the presence of the sub-operating mode B1H. However, the sub-operating mode B1V may also exist in the no-electric-field state.

[0146] Thus, the switchable filter 5 of the first technical solution allows switching between vertical privacy protection and horizontal privacy protection (upper / lower protection B1V and left / right protection B1H) in cooperation with the image reproduction unit. Taking a laptop computer as an example, this means that in the sub-operating mode B1V, the user can watch the content with other people around the user whose eyes are substantially at the same height, while in the sub-operating mode B1H, the people next to the user cannot see the image content. As further mentioned above, the switchable filter 5 of the third technical solution can be changed in structure.

[0147] at last, Fig.10 As a schematic diagram of the principle, a second technical solution of a switchable filter 5 is shown. The structure of the first optical component 1 is similar to that of the optical component 1 of the first technical solution, except that it is switchable, that is, the transition dipole moment of each of the layers S1 and S2 can change its orientation and / or its absolute value between a first state and at least one second state, so that each layer S1, S2, ... can be alternately placed in at least two different states. A polarization filter P is provided upstream or downstream of the first optical component 1. The figure still does not show a component for selectively generating a first electric field EF1 or a second electric field EF2, wherein, for the first optical component 1, the first state is generated by applying the first electric field EF1, and the second state is generated by applying the second electric field.

[0148] In the first operating mode B1, in which the first electric field EF1 is applied and the transition dipole moments of the layers S1, S2, ... of the first optical component 1 are oriented along the first preferred direction and have the first sub-operating mode B1H and the second sub-operating mode B1V, on the one hand, at least 24% of the non-polarized light incident on the switchable filter 5 parallel to the first preferred direction is transmitted, and on the other hand, at least 85% of the non-polarized light incident on the switchable filter 5 at an angle of more than 30° to the first preferred direction is absorbed, wherein the absorption occurs only in the first direction in the first sub-operating mode B1H and only in the second direction perpendicular to the first direction in the second sub-operating mode B1V. In addition, preferably, the first preferred direction is still parallel to the perpendicular bisector of the switchable filter 5 in the drawing plane. With regard to the positions of the first and second directions, the implementation scheme proposed in relation to the third technical solution can be similarly applied.

[0149] In a second operating mode B2, in which a second electric field EF2 is applied, the transition dipole moments of the layers S1, S2, ... of the first optical component (1) are oriented parallel to the surface of the polarization filter P (also referred to as substrate in this case) and perpendicular to the transmission direction of the polarization filter P. Thus, at least 24% of unpolarized light incident on the switchable filter (5) at an arbitrary angle to the first preferred direction is transmitted.

[0150] Here, the field-free state can also be described, for example, by the electric field EF1 or the electric field EF2, while the other electric field EF2 or EF1 has an absolute field strength greater than zero (for example 0.5 MV / m). Therefore, depending on the design of the optical component 1 and the polarization filter P, the field-free state may mean that the operating mode B2 exists. However, it is also possible that the operating mode B1 with one of the sub-operating modes B1H or B1V exists in the field-free state.

[0151] Therefore, the switchable filter 5 of the second technical solution, in cooperation with the image reproduction unit, allows switching between anti-peeping protection and no anti-peeping effect (up / down protection B1V or left / right protection B1H and no anti-peeping protection B3) in the vertical or horizontal direction.

[0152] For special applications, no matter which of the above technical solutions is adopted, the switchable filter 5 can be divided into a plurality of individually switchable parts, so as to realize local switching between possible working states. In cooperation with the image reproduction unit, this means that, for example, only a part of the image area can be switched between privacy protection and free viewing without privacy protection, while the complementary image area is always in privacy protection mode or in non-privacy protection mode. There can even be a plurality of such parts that are geometrically separated from each other and can be switched between working modes individually or together.

[0153] As mentioned above, the switchable filter 5 can be combined with the image reproduction unit to form a screen. Such a screen can work in at least the first working state B1V and / or B3 to achieve a horizontal free field of view mode, and can work in at least the second working state B1H and / or B2 to achieve a horizontal restricted field of view mode, and such a screen comprises: the switchable filter 5 as mentioned above in one of the above four technical solutions, and the image reproduction unit arranged downstream or upstream of the switchable filter 5 from the perspective of the viewer 6.

[0154] Advantageously, the image reproduction unit corresponds to an LCD panel, one polarization filter of which corresponds to the polarization filter P. It can thus be a front polarizer or a back polarizer in the LCD structure. Furthermore, advantageously, a switchable filter is arranged between the LCD panel and its backlight in order to switch between a first operating state B3 (or B1V) in free field of view mode and a second operating state B1H or B2 in restricted field of view mode, since the light of the backlight is sometimes focused (B2 or B1H) and sometimes not focused (B3 or B1V) in the horizontal direction due to the switchable filter. Furthermore, "focusing" does not mean focusing in the manner of a lens, but rather a reduction in the emission range or transmittance depending on the angle of incidence.

[0155] Such a screen is advantageously used in mobile devices, cars, aircraft or ships, payment terminals or access systems, wherein it is possible to switch between the above-mentioned operating modes to protect sensitive data, i.e. to present the image content perceptibly only to one viewer or selectively to present the image content to multiple viewers simultaneously.

[0156] In the above-mentioned optical component, the light entering and passing through the optical component is transmitted or partially or completely absorbed depending on its incident direction and polarization properties. The switchable filter using such an optical component affects the transmission of light depending on the angle (optionally vertical), wherein it is possible to switch between at least two operating states of at least a free field of view mode (with respect to the viewing angle range of the viewer) and a restricted field of view mode. In addition, in particular, the angular limitation of the transmission in certain directions is switchable. The optical component or the system based on the optical component is low-cost to realize and can be universally used for different types of screens in particular to realize the switch between anti-peep protection (at least in the horizontal direction) and a free field of view mode, wherein the resolution of such a screen is not reduced in principle.

[0157] The above invention can be advantageously used in combination with an image reproduction device at various locations where confidential data is displayed and / or entered, such as entering a PIN code or display data at an ATM or payment terminal, or entering a password, or reading an email on a mobile device. As mentioned above, the invention can also be used in passenger cars to selectively block disturbing image content to the driver or passengers.

[0158] Reference numerals list

[0159] 1. First optical component

[0160] 2 Second optical component

[0161] 3 Liquid crystal layer

[0162] 4 Orientation layer

[0163] 5 Switchable filters

[0164] 6 Viewers

[0165] 7 Optically anisotropic layer

[0166] Area A1…A5

[0167] E1, E2 electrodes

[0168] E2 Second electric field

[0169] P Polarizing filter

[0170] S Transparent Substrate

[0171] S1…S3 layers

Claims

1. An optical component, comprising: comprising a first layer (S1) of a material having a plurality of light-absorbing transition dipole moments, each transition dipole moment is oriented parallel to a selectable first preferred direction with a tolerance of at most 10°, at least in a first state, so that light incident on the optical component is transmitted or at least partially absorbed depending on its direction of incidence relative to the first layer (S1) and its polarization state, wherein the material comprises at least one dye, and Wherein the at least one dye is a dichroic dye mixture.

2. The optical component according to claim 1, characterized in that The preferred directions each make an angle between 0° and 45° with the surface normal of the first layer (S1).

3. The optical component of claim 1 , further comprising a second layer of a material having a plurality of light-absorbing transition dipole moments, each transition dipole moment being oriented parallel to a selectable second preferred direction with a tolerance of up to 10° at least in a first state, such that light incident on the optical component is transmitted or at least partially absorbed depending on its direction of incidence relative to the second layer and its polarization state, and, in, The first preferred direction and the second preferred direction differ by more than 10° in a selectable plane.

4. The optical component according to claim 1, characterized in that Each of the first preferred directions of the transition dipole moments may be selected depending on the position of the transition dipole moment in the first layer (S1).

5. The optical component according to claim 1, characterized in that The first layer (S1, S2, ...) is divided into different areas (A1, A2, ...) along a selectable reference line of the first layer (S1), wherein for each area (A1, A2, ...) an own area preferred direction is selectable, said area preferred direction being applicable to all transition dipole moments of the corresponding layer (S1, S2) located within the area (A1, A2, ...), wherein all area preferred directions are different from each other in pairs and point in the direction of a viewer with a maximum tolerance of + / - 10 degrees.

6. The optical component according to claim 1, characterized in that The material comprises liquid crystal.

7. The optical component according to claim 1, characterized in that The optical assembly is constructed as a laminate of multiple layers of polymeric thin film polarizers.

8. An illumination device for a screen, configured to operate in at least two operating modes, a first operating mode (B1) for a free field of view mode and a second operating mode (B2) for a restricted field of view mode, and comprising: A planarly extending backlight comprising the optical assembly of claim 1, wherein the backlight is configured to be turned on in the second operating mode. a plate-like light guide arranged in front of the backlight in the viewing direction and having a decoupling component on the surface of the light guide and / or within the volume of the light guide, wherein the light guide is transparent for at least 40% of the light emitted from the backlight, a light emitting member arranged laterally on at least one narrow side of the light guide, the light emitting member being configured to be turned on in a first operating mode and turned off in a second operating mode, A linear polarization filter is arranged in front of the backlight or in front of the light guide in the viewing direction, whereby light emitted from the backlight and passing through the polarization filter is limited in its propagation direction.

9. The lighting device according to claim 8, characterized in that: The light guide is transparent to at least 70% of the light emitted from the backlight.

10. A screen capable of operating in at least two operating modes, a first operating mode (B1) for a free field of view mode and a second operating mode (B2) for a restricted field of view mode, and comprising: A planarly extending backlight comprising the optical assembly of claim 1, wherein the backlight is configured to be turned on in the second operating mode. a plate-like light guide which is arranged in front of the backlight in the viewing direction and has a decoupling component on its surface and / or in its volume, wherein the light guide is transparent for at least 40% of the light emitted by the backlight, a light emitting member arranged laterally on at least one narrow side of the light guide, the light emitting member being configured to be turned on in a first operating mode and turned off in a second operating mode, a linear polarization filter arranged in front of the backlight or in front of the light guide in the viewing direction, whereby the light emitted from the backlight and passing through the polarization filter is limited in its propagation direction, A transmissive image reproduction device is arranged before the light guide in the viewing direction, and the linear polarization filter is arranged in the image reproduction device.

11. The screen according to claim 10, characterized in that The light guide is transparent to at least 70% of the light emitted from the backlight.

12. The screen according to claim 10, characterized in that The linear polarization filter is arranged in the image reproduction device or is part of the image reproduction device.

Images