Methods and Structures for Affecting the Propagation Direction of Light

Abstract

The present invention relates to a method for influencing the light propagation direction of at least one light-emitting surface (F), the light-emitting surface (F) emitting light in a first wavelength range Δλ1 in a first spatial direction R1 and emitting light in a wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a spatial direction R2 different from the first spatial direction R1, the wavelength ranges Δλ1 and Δλ2 having a spectral radiant density associated with the wavelength and being different at least in terms of the peak wavelength, and a switchable color converter (7) being arranged in front of the light-emitting surface (F) in the viewing direction, the method comprising the following steps: a) deactivating the color converter (7) in a first mode so as to transmit the second wavelength range Δλ2 and absorb the first wavelength range Δλ1, whereby the light emitted from the light-emitting surface (F) can only be perceived from the second spatial direction R2, or b) activating the color converter (7) in a second mode so as to convert the light in the first wavelength range Δλ1 into light in the second wavelength range Δλ2 and transmit the light in the second wavelength range Δλ2, whereby the light emitted from the light-emitting surface (F) can be perceived from both spatial directions R1, R2.

Description

Technical Field

[0001] In recent years, OLED panels with excellent wide viewing angles have been increasingly used to display image content. However, in some cases, this very large viewing area in the display screen can be a disadvantage. More and more, information such as bank data or other personal and sensitive data can be obtained on mobile devices such as laptops, tablets, and mobile phones. Therefore, it is necessary to monitor the viewing access to this sensitive data. People must be able to choose to share the information on the display screen with others between wide viewing angles, for example, when viewing vacation photos or for advertising purposes. On the other hand, when people want to keep the displayed information confidential, they need a very small viewing angle.

[0002] Currently, there is no method on the market for the switchability of the viewing angle to provide dimming for viewing from a side angle in a restricted viewing angle.

[0003] A similar problem also appears in automotive engineering. In this case, the driver must not be distracted by image content (such as digital entertainment programs) when the engine is started, but the passengers want to view this image content during driving. Therefore, a display screen that can switch between corresponding display modes is needed, so that the image content can be selectively visible only to the passengers or visible to both the driver and the passengers at the same time. Background Art

[0004] Additional thin films based on micro-thin layers have been used in mobile displays to protect visible data. However, these thin films cannot be switched (back and forth), and they always have to be manually applied first and then removed. In addition, when the thin films are not used immediately, these thin films have to be transported separately from the display. Another major disadvantage of using such thin-layer films is related to the light loss caused.

[0005] US2007 / 030240A1 describes an optical element for controlling the light propagation direction of light originating from backlighting. For example, such an optical element requires liquid crystals in the form of PDLC, which is expensive on the one hand and has safety risks, especially for end-customer applications, because PDLC liquid crystals usually require a voltage higher than 60V for their circuits.

[0006] Document DE102016206681B3 describes the structures and respective configurations of two organic light-emitting diodes (OLEDs). Here, the light-emitting characteristics of the two OLEDs are different: one OLED emits basically in a coaxial viewing angle, while the other OLED emits basically in an off-axis viewing angle. The disadvantage of this structure is that the two organic light-emitting diodes must be manufactured on top of each other and the additional electrodes in the LEDs must be monitored. Summary of the Invention

[0007] Accordingly, the object of the present invention is to introduce a method and a structure for influencing the direction of light propagation. The present invention should be particularly applicable to OLED pixels or OLED displays and achieve operating states of free viewing and restricted viewing. In addition, the present invention can be implemented at low cost and is generally applicable to various types of displays so as to be able to switch between a protected viewing mode and a free viewing mode, wherein the resolution of such a display should not be significantly reduced.

[0008] According to the present invention, the above object is achieved by a method for influencing the direction of light propagation of at least one light-emitting surface F, the light-emitting surface F emitting light in a first wavelength range Δλ1 in a first spatial direction R1 and emitting at least partially a wavelength range Δλ2 different from the first wavelength range Δλ1 in a spatial direction R2 different from the first spatial direction R1, the wavelength ranges Δλ1 and Δλ2 having a spectral radiant density associated with the wavelength and being different at least in terms of the peak wavelength (and may also partially overlap), and a switchable color converter being arranged in front of the light-emitting surface F in the viewing direction, the color converter absorbing light of a shorter wavelength and transmitting light of a longer wavelength in the deactivated state, and converting light of a shorter wavelength into light of a longer wavelength and transmitting light of a longer wavelength in the activated state, the method comprising the following steps:

[0009] In a first mode, the color converter is deactivated such that light in the second wavelength range Δλ2 is transmitted while light in the first wavelength range Δλ1 is absorbed, whereby the light emitted from the light-emitting surface F can only be perceived from the second spatial direction R2, or

[0010] In a second mode, the color converter is activated such that light of the first wavelength Δλ1 is at least partially converted into light in the second wavelength range Δλ2 and light in the second wavelength range Δλ2 is transmitted, whereby the light emitted from the light-emitting surface F can be perceived from two spatial directions R1, R2.

[0011] Regarding the working mode, it is worth noting that: when the color converter is not activated, the color converter absorbs light of the shorter wavelength in the first wavelength range Δλ1. At the same time, the color converter can let light of the longer wavelength Δλ2 pass through. However, if the color converter is activated, the color converter converts light of a shorter wavelength into light of a longer wavelength and lets light of a longer wavelength pass through without significantly affecting the direction of propagation of the light. At the same time, the color converter magnifies the wavelength of the light passing through the color converter substantially independently of the wavelength itself.

[0012] Each of the wavelength ranges Δλ1 or Δλ2 may have one or more peaks of the associated spectral radiant density distributed over the visible spectrum. If the wavelength range Δλ1 has a peak, the wavelength range Δλ1 preferably has a shorter wavelength than the peak of the wavelength range Δλ2.

[0013] It should also be noted that, without limiting generality, in the above method according to the present invention, a wavelength range Δλ1 is emitted in the spatial direction R1 and a wavelength range Δλ2 is emitted in the spatial direction R2. This correspondence should also apply to the following designs of the present invention. Of course, R1 and R2 can also be interchanged without departing from the scope of the present invention.

[0014] The "spatial direction" R1 or R2, of course, refers to a spatial angle that unfolds in one or two planes and includes several degrees to a certain degree in each plane. However, it is also feasible that, for example, the spatial direction R1 is shaped like a cone outward, and a second cone, such as a cone of the second spatial direction R2, is cut out inside the cone, so that the two spatial directions R1 and R2 together form the shape of a complete cone. Correspondingly, the distances of the spatial directions together give a larger spatial angle. The fact that the spatial directions R1 and R2 are different does not mean that they cannot have a certain overlap. However, in the overlapping region, the above method has no large-scale influence on the propagation direction of the light emitted from the light-emitting surface F.

[0015] The light-emitting surface F generally forms the uppermost surface of a layered body (such as an OLED pixel), and light with pre-given or pre-givable emission characteristics is emitted from the layered body. In the case of such a self-luminous diode, for simplicity, the light-emitting surface actually illuminated from below the surface is also referred to as self-luminous, even if there are additional layers, such as a semi-transparent electrode or a substrate layer, between the uppermost emitter layer and the light-emitting surface, which is also referred to as the emission surface. However, the light-emitting surface F can also be illuminated in other ways. In this case, the light-emitting surface F is also referred to as "illuminated", for example, in the case of the surface of an LCD panel backlit by backlighting.

[0016] The spectral radiant density of each wavelength range varies according to the wavelength within the respective range. The wavelength with the highest spectral radiance on the light-emitting surface is also referred to as the peak wavelength. A wavelength range can also have multiple peak wavelengths, which are then respectively the local maxima of the spectral radiant density.

[0017] The switchable color converter can preferably be formed by quantum dots. Each color converter has a large number of quantum dots. For example, each quantum dot can have a spatial extension of at most 100 nm, preferably at most 50 nm, and particularly preferably at most 20 nm. Materials contemplated for quantum dots are, for example, semiconductor nanocrystals such as: CdSe, CdS, CdTe, ZnSe, ZnTe, ZnS, HgTe, InAs, InP, GaAs, GaP, GaInP2, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeT, CdZn, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSeS, HgZnSeSe, HgZnSeS, GaN, AlN, AlP, AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs, GaInPAs, InAlNP, InAlNAs and / or InAlPAs. Doped graphene, silicon and synthetic perovskites are also contemplated. Other configurations are possible.

[0018] In order to achieve full color in both modes, for each of the three primary colors - red, green and blue, there are preferably wavelength range pairs within the wavelength ranges Δλ1 and Δλ2, such as violet / blue, blue / green and green / red. This type of full-color separation is known to the person skilled in the art from Dolby TM 3D glasses or from the corresponding interference filter technology of separating the light of the three primary colors red, green and blue into two different wavelength ranges each by a filter. This principle can also be applied in a corresponding manner within the framework of the present invention. The incomplete absorption of the color converter can be compensated by adding a suitable color filter.

[0019] "Wavelength range pair" means two peaks close together in the spectrum ("close" shall mean that they are a few nanometers apart up to about 200 nm, preferably up to 100 nm), where one peak is located within the wavelength range Δλ1 and one peak is located within the wavelength range Δλ2. If, as described above, there are three pairs for full-color display, this correspondingly means that the corresponding three peaks within the wavelength range Δλ1 do not occur identically within the wavelength range Δλ2, but are included in the spectrum shifted by from a few nanometers to about 200 nm, preferably up to 100 nm. Here, minor overlaps within the pair are not considered.

[0020] In the case of using full colors as described above, two or three or even more such color converters can be provided according to the configuration.

[0021] For a specific configuration, it is advantageous that the switchable color converter does not cover the entire self-luminous or illuminated light-emitting surface F, but only covers its actual sub-region.

[0022] Furthermore, it is advantageous that the switchable color converter is deactivated by applying an electric field and is activated in the absence of an electric field.

[0023] In addition, preferably, a plurality of self-luminous light-emitting surfaces (F) are provided, and each light-emitting surface corresponds to the emission surface of the smallest pixel configured as a layer body of a QLED display screen, an OLED display screen, a miniLED display screen, an LED display screen, or a micro-LED display screen, respectively. Depending on the structure of the imaging device, the smallest pixel can be a color sub-pixel (e.g., red, green, blue), a monochromatic pixel, or a pixel available for full colors. LCD, SED, FED, or other display types can also be considered, and the smallest pixel thereof corresponds to a large number of self-luminous light-emitting surfaces F. The pixels or sub-pixels preferably have the same size, but can also have different dimensions in groups or even individually.

[0024] In addition, electro-optical components can also be provided in the layer body of such a smallest pixel. The electro-optical components change the emission characteristics of the light-emitting surface (F), and the electro-optical components are preferably designed as DBR (Distributed Bragg Reflector), a semi-transparent mirror, a wave plate, a liquid crystal layer, an electrochromic layer, an electro-wetting element, a switchable absorber, or designed as a phase change material, such that at least in the first spatial direction R1, light in the first wavelength range Δλ1 is emitted instead of light in the second wavelength range Δλ2. Here, it is important that the light in the second wavelength range Δλ2 is collimated, that is, restricted to a certain propagation direction R2. In the case of the OLED-based light-emitting surface F, for example, the emission characteristics can be changed by changing the resonance conditions of the OLED. In the case of QLED, by changing the resonance conditions, the spontaneous emission in the thin-film resonator is converted into stimulated emission, thereby affecting the light-emitting characteristics.

[0025] In this variant of the present invention, as in all the following variants, the restricted viewing mode does not necessarily mean that there is no light emission at all in certain directions. On the contrary, a certain amount of residual light can also be emitted, although it interferes with comfortable viewing. In the area provided for restricted viewing, the typical value of such residual light (measured by brightness) is a few percent (e.g., 1% to at most 5%) of the peak value perceptible in the dedicated viewing area of the unrestricted viewing area.

[0026] The above object of the present invention is also achieved by a second method for influencing the light propagation direction of at least one light-emitting surface F, wherein:

[0027] In a first mode, the light-emitting surface F selectively emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a second wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a second spatial direction R1 different from the first spatial direction R1, or in a second mode, emits light in at least the second wavelength range Δλ2 in two spatial directions R1, R2. The wavelength ranges Δλ1 and Δλ2 have a spectral radiation density associated with the wavelength and are different from each other at least in terms of the peak wavelength (but may also partially overlap). At least one color filter is arranged in front of the light-emitting surface F along the viewing direction. The color filter absorbs light in the wavelength range Δλ1 and transmits light in the wavelength range Δλ2. The method includes the following steps:

[0028] Activate the first mode, wherein the light in the second wavelength range Δλ2 can only be perceived from the second spatial direction R2 after passing through the color filter, or

[0029] Activate the second mode, wherein the light in the second wavelength range Δλ2 can be perceived from both spatial directions R1, R2 after passing through the color filter.

[0030] Particularly preferably, herein, in the first mode, the light in the wavelength range Δλ2 is collimated, that is, the spatial direction R2 includes a relatively narrow cone, for example, having an apex angle of at most 30 degrees, and in the second mode, the light is not collimated, that is, the spatial directions R1 and R2 complement each other to form a wide spatial angle with an apex angle of at least greater than 40 degrees.

[0031] Advantageously, a plurality of self-luminous light-emitting surfaces F are provided, and each of the light-emitting surfaces corresponds to the emission surface of the smallest pixel constructed as a layer body of a QLED display screen, an OLED display screen, a miniLED display screen, an LED display screen, or a micro-LED display screen.

[0032] In addition, in the laminate of each light-emitting surface F disposed below the light-emitting surface F, there is an electro-optical component that changes the resonance condition in the laminate, and the electro-optical component is preferably designed as a DBR (Distributed Bragg Reflector), a semi-transparent mirror, a wave plate, a liquid crystal layer, an electrochromic layer, an electro-wetting element, a switchable absorber, or designed as a phase change material (so-called "Phase Changing Material"). By means of the electro-optical component, the collimation of light in the wavelength range Δλ2 can be started and interrupted. This precisely means that, by means of the corresponding electro-optical component, in the first mode, the emission characteristics of each light-emitting surface F are affected such that at least part of the light in the different wavelength ranges Δλ1 and Δλ2 is emitted in different spatial directions R1, R2, and in the second mode, the light in at least one wavelength range Δλ2 is emitted in the spatial directions R1, R2. Thereby, it is also achieved that the light in the wavelength range Δλ1 is emitted outside the dedicated viewing area, that is, in the first mode, it is emitted in the spatial direction R2 but is absorbed by the color filter. In other words, the light emitted from the light-emitting surface F in the (multiple) spatial direction R1 is converted in terms of color between the two modes, that is, it is possible to switch between emitting the light in the wavelength range Δλ1 and emitting the light in the wavelength range Δλ2 in the spatial direction R1. For an OLED, this is achieved, for example, by switching between a resonant state and a non-resonant state. In the non-resonant state, light of the same wavelength is emitted in all spatial directions R1, R2. In the resonant state corresponding to the first mode, the wavelength changes with the viewing angle or the spatial angle such that, due to the color filter, the light can only be perceived in the second spatial direction R2.

[0033] Preferably, for full-color display, for each of the three primary colors of red, green, and blue, there is at least one pair of internal wavelength ranges within the first wavelength range Δλ1 and the second wavelength range Δλ2. For each pair of internal wavelength ranges, one of the two peaks separated by several nanometers to several tens of nanometers and up to approximately 200 nm in the spectrum is in the first wavelength range Δλ1, and the other peak is in the second wavelength range Δλ2.

[0034] The special significance of the present invention lies in the use of the above method to generate the first operating state B1 for a restricted viewing mode and the second operating state B2 for a free viewing mode in a display screen whose minimum pixel has an electro-optical component and a light-emitting surface F as detailed above. The switchable color converter is deactivated to generate the first operating mode B1, and the switchable color converter is activated to generate the second operating mode B2.

[0035] The object of the present invention is also achieved by a structure for influencing the light propagation direction of at least one self-luminous or illuminated light-emitting surface F, wherein the light-emitting surface F (for example, when the light-emitting surface F is a pixel of a resonant OLED display) emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a second wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a second spatial direction R2 different from the first spatial direction R1. The wavelength ranges Δλ1 and Δλ2 have a spectral radiant density associated with the wavelength and are different at least in terms of the peak wavelength (and may also partially overlap). This structure further includes a switchable color converter arranged in front of the light-emitting surface F along the viewing direction. The color converter preferably includes quantum dots, wherein:

[0036] The color converter is deactivated in the first mode, allowing the light in the second wavelength range Δλ2 to be transmitted while the light in the first wavelength range Δλ1 is absorbed. Thus, the light emitted from the light-emitting surface F can only be perceived from the second spatial direction R2. And the color converter is activated in the second mode, such that at least part of the light in the first wavelength range Δλ1 is converted into the light in the second wavelength range Δλ2, and the light in the second wavelength range Δλ2 is transmitted. Thus, the light emitted from the light-emitting surface F can be perceived from both spatial directions R1 and R2.

[0037] The switchable color converter is generally deactivated by applying an electric field and is activated in the absence of an electric field.

[0038] Finally, the object of the present invention is achieved by a structure for influencing the light propagation direction of at least one self-luminous or illuminated light-emitting surface F in the first wavelength range Δλ1 in the first spatial direction R1 and the light propagation direction of light in a second wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 and is emitted in a second spatial direction R2 different from the first spatial direction R1. And in the second mode, at least the light in the second wavelength range Δλ2 is emitted in both spatial directions R1 and R2 (for example, the light-emitting surface F can correspond to the emission surface of pixels of an OLED display that emit light with a shorter wavelength laterally). The wavelength ranges Δλ1 and Δλ2 have a spectral radiant density associated with the wavelength and are different at least in terms of the peak wavelength (and may also partially overlap). This structure further includes at least one color filter arranged in front of the light-emitting surface F along the viewing direction. The color filter absorbs the light in the first wavelength range Δλ1 and transmits the light in the second wavelength range Δλ2, wherein,

[0039] Activate the first mode, wherein the light in the second wavelength range Δλ2 is transmitted by the color filter while the light in the first wavelength range Δλ1 is absorbed by the color filter. Thus, after passing through the color filter, the light emitted from the light-emitting surface F can only be perceived from the second spatial direction R2, or

[0040] Activate the second mode, wherein light in the second wavelength range Δλ2 is transmitted by the color filter, so that the light emitted from the light-emitting surface F can be perceived from two spatial directions R1 and R2 after passing through the color filter.

[0041] The above structure can be extended in the following manner. Further, in each layer-like body of the self-luminous or illuminated light-emitting surface F, there are switchable DBRs (Distributed Bragg Reflectors), switchable mirrors, and / or switchable wave plates, so that the emission of light in the wavelength range Δλ1 can be started and interrupted. In particular, the switchable DBR can be responsible for causing the light-emitting surface F to emit light in at least two partially different wavelength ranges Δλ1 and Δλ2 in different spatial directions R1 and R2 in the first mode, and to emit at least the second wavelength range Δλ2 of light in the spatial directions R1 and R2 in the second mode.

[0042] The above-mentioned structural variants and the functional relationships of the means, which are not repeated here for redundancy reasons, are reasonably applicable here.

[0043] When the above parameters vary within certain boundaries, the performance of the present invention remains essentially unchanged in principle.

[0044] Of course, the features mentioned above and those to be explained later can not only be used in the described combination, but also in other combinations or alone, without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Hereinafter, the present invention will be explained in more detail with reference to the drawings, which also show the features crucial for the present invention.

[0046] Wherein:

[0047] Figure 1 Shows a schematic diagram of the structure of an OLED pixel according to the prior art;

[0048] Figure 2 Shows a schematic diagram of the first design of the method according to the present invention;

[0049] Figure 3 Shows according to Figure 2 A schematic diagram of the operation mode of the first design of the method according to the present invention;

[0050] Figure 4 Shows according to Figure 2 A schematic diagram of an improved version of the first design of the method according to the present invention;

[0051] Figure 5 Shows a schematic diagram of the second design of the method according to the present invention;

[0052] Figure 6 shows the working principle diagram of a second design of the method according to the present invention in accordance with Figure 5 ; the schematic diagram of the working mode of the second design of the method according to the present invention;

[0053] Figure 7 shows the schematic diagram of the third design of the method according to the present invention; and

[0054] Figure 8 shows an exemplary graph of the wavelength ranges Δλ1 and Δλ2 of the corresponding example. Detailed implementation mode

[0055] The drawings are not drawn to actual scale and only reflect the schematic diagrams.

[0056] In Figure 1 is reflected a schematic diagram of the structure of the laminate of an OLED pixel according to the prior art. Below the transparent substrate 1 (made of glass or polymer, for example) in the viewing direction is a semi-transparent first electrode 2 (anode, for example), an organic layer 3, then an emission layer 4, below which is again an organic layer 5, and finally a mirror with a second electrode 6, a cathode, for example. Usually, especially in the laminate, the organic layers 3 and 5 may be significantly more complex. In a design with (at least) one OLED pixel as the (self-luminous) light-emitting surface F, the fact is fully utilized that the light from the OLED with a lateral emission angle has a shorter wavelength than the vertically emitted light.

[0057] In this regard, Figure 2 shows the schematic diagram of the first design of the method according to the present invention, and the first design is based on the OLED structure in accordance with Figure 1 . A method according to the present invention for influencing the light propagation direction of at least one self-luminous or illuminated light-emitting surface F, wherein the light-emitting surface F emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a spatial direction R2 different from the first spatial direction R1, and the wavelength ranges Δλ1 and Δλ2 have a spectral radiant density associated with the wavelength and are different at least in terms of the peak wavelength (and may also partially overlap), and a switchable color converter 7 is arranged in front of the light-emitting surface F in the viewing direction, which, in the deactivated state, absorbs shorter-wavelength light while transmitting longer-wavelength light, and in the activated state, converts shorter-wavelength light into longer-wavelength light and transmits longer-wavelength light. The method includes the following steps:

[0058] In the first mode, the color converter 7 is deactivated such that light in the second wavelength range Δλ2 is transmitted and light in the first wavelength range Δλ1 is absorbed. As a result, the light emitted from the light-emitting surface F can only be perceived from the second spatial direction R2, or

[0059] In the second mode, the color converter 7 is activated such that light in the first wavelength range Δλ1 is at least partially converted into light in the second wavelength range Δλ2 and light in the second wavelength range Δλ2 is transmitted. As a result, the light emitted from the light-emitting surface F can be perceived from two spatial directions R1, R2.

[0060] It should also be noted that, without limiting generality, the first wavelength range Δλ1 is emitted in the first spatial direction R1 and the second wavelength range Δλ2 is emitted in the second spatial direction R2. This correspondence should also apply to the following designs of the present invention. Of course, the two spatial directions R1 and R2 can also be interchanged without departing from the scope of the present invention.

[0061] In Figure 2 the light-emitting surface F is symbolically shown (as a sectional view) by a thick black line. In reality, however, the area of its surface is from a few square micrometers to usually a few square millimeters. The light-emitting surface F is oriented perpendicular to the plane of the schematic diagram.

[0062] In Figure 3 a schematic diagram of the working mode of a first design of the method according to the present invention is shown.

[0063] The color converter 7 is deactivated in the first mode (right figure) such that light in the second wavelength range Δλ2 (here represented by "R" for light with a relatively long average wavelength, for example, usually red light) is transmitted and light in the first wavelength range Δλ1 (here represented by "B" for light with a relatively short average wavelength, for example, usually blue light) is absorbed. As a result, the light emitted from the light-emitting surface F can only be perceived from the (restricted) second spatial direction R2.

[0064] Conversely, the color converter 7 is activated in the second mode ( Figure 3 left figure in) such that light in the first wavelength range Δλ1 is converted into light in the second wavelength range Δλ2, and light in the second wavelength range Δλ2 is transmitted. As a result, the light emitted from the light-emitting surface F can be perceived from two spatial directions R1, R2.

[0065] The switchable color converter 7 can preferably be formed by quantum dots, where there are a large number of quantum dots for each color converter. For example, each quantum dot can have a spatial extension of at most 100 nm, preferably at most 50 nm, and particularly preferably at most 20 nm. The switchable color converter 7 does not have to be connected to the substrate 1.

[0066] Of course, the "spatial directions" R1 or R2 refer to spatial angles that are unfolded on one or two planes and include several degrees to a certain degree in each plane. It is also possible that, for example, the spatial direction R1 is shaped conically outward, and a second cone, for example, the cone of the second spatial direction R2, is cut out inside this cone, such that the two spatial directions R1 and R2 together give the shape of a complete cone. Accordingly, multiple spatial directions together achieve a larger spatial angle. The fact that the spatial directions R1 and R2 are different from each other does not mean that the spatial directions cannot have a certain overlap. However, in the overlapping region, the propagation direction of the light emitted from the light-emitting surface F is not significantly affected by the above method.

[0067] Materials considered as quantum dots are, for example, semiconductor nanocrystals, such as: CdSe, CdS, CdTe, ZnSe, ZnTe, ZnS, HgTe, InAs, InP, GaAs, GaP, GaInP, HgS, HgSe, HgTe, CdSeS, CdSeTe, CdSTe, ZnSeS, ZnSeTe, ZnSTe, HgSeS, HgSeT, CdZn, CdZnTe, CdHgS, CdHgSe, CdHgTe, HgZnS, HgZnSe, HgZnTe, CdZnSeS, CdZnSeTe, CdZnSTe, CdHgSeS, CdHgSeTe, CdHgSeS, HgZnSeSe, HgZnSeS, GaN, AlN, AlP, AlAs, InN, InP, InAs, GaNP, GaNAs, GaPAs, AlNP, AlNAs, AlPAs, InNP, InNAs, InPAs, GaAlNP, GaAlNAs, GaAlPAs, GaInNR, GaInPAs, InAlNP, InAlNAs and / or InAlPAs. Other types of quantum dots can also be used, such as graphene, synthetic perovskite or silicon.

[0068] For a specific configuration, it is helpful that the switchable color converter 7 does not cover the entire self-luminous or illuminated light-emitting surface F but only its actual sub-region. This is shown Figure 4 here. Here, the color converter 7 only partially overlaps with the light-emitting surface F, specifically at the edges. The color converter 7 is used for the light emitted obliquely and not for the light emitted vertically.

[0069] Advantageously, the switchable color converter 7 is deactivated by applying an electric field and activated without applying an electric field.

[0070] Additionally, preferably, there are a plurality of self-luminous light-emitting surfaces (F), and each of the light-emitting surfaces corresponds to the emission surface of the smallest pixel with a laminated structure of a QLED display screen, an OLED display screen, a miniLED display screen, an LED display screen, or a micro-LED display screen. Depending on the structure of the imaging device, the smallest pixel can be a color sub-pixel (e.g., red, green, blue), a monochromatic pixel, or a pixel available for full color. LCD, SED, FED, or other display types can also be considered, and the smallest pixel thereof corresponds to a plurality of illuminated or self-luminous light-emitting surfaces F.

[0071] In addition, a DBR (Distributed Bragg Reflector), a semi-transparent mirror, an additional emission layer, and / or a wave plate can be provided in the laminated body of such a smallest pixel, so that at least in the first spatial direction R1, light in the first wavelength range Δλ1 is emitted instead of light in the second wavelength range Δλ2. Such additional elements of this type can also be switchable. For example, a switchable "DBR" can be realized by a liquid crystal or a phase change material. Here, it is important that the light in the second wavelength range Δλ2 is collimated, that is, restricted to a certain propagation direction R2.

[0072] In addition, Figure 5 The schematic diagram of the second design of the method according to the present invention is shown. Here, in the first mode, the light-emitting surface F selectively emits light in the first wavelength range Δλ1 in the first spatial direction R1 and emits at least partially different light in the second wavelength range Δλ2 different from the first wavelength range Δλ1 in a second spatial direction R2 different from the first spatial direction; or, in the second mode, emits at least light in the second wavelength range Δλ2 in the two spatial directions R1, R2. The wavelength ranges Δλ1 and Δλ2 have spectral radiant densities associated with wavelengths and are different (can also partially overlap) at least in terms of one peak wavelength or a plurality of peak wavelengths, and a color filter 8 is arranged in front of the light-emitting surface F along the viewing direction, and the color filter absorbs the light in the wavelength range Δλ1 and transmits the light in this wavelength range. Here, particularly preferably, the light in the wavelength range Δλ2 is collimated in the first mode and not collimated in the second mode.

[0073] Starting from this, the second design of the method according to the present invention includes the following steps:

[0074] Activate the first mode, in which the light in the second wavelength range Δλ2 can only be perceived from the second spatial direction R2 after passing through the color filter 8, or

[0075] Activate the second mode, in which the light in the second wavelength range Δλ2 can be perceived from the two spatial directions R1, R2 after passing through the color filter 8.

[0076] This method of operation of the second embodiment of the method according to the invention is shown as a schematic diagram in Figure 6 It is shown in the figure: when the first mode is activated (right side of the figure), the light in the second wavelength range Δλ2 (here "R" indicates light with a longer average wavelength) is transmitted, and the light in the first wavelength range Δλ1 (here "B" indicates light with a shorter average wavelength) is absorbed, so that the light emitted by the light-emitting surface F can be perceived only from one spatial direction R2 after passing through the color filter 8. On the other hand, if the second mode is activated so that the light (R) in the second wavelength range Δλ2 is transmitted, the light emitted by the light-emitting surface F can be perceived from spatial directions R1 and R2 after passing through the color filter 8. As shown on the left side of the figure.

[0077] In addition, according to Figure 5 As a variation of the above method, a switchable DBR (Distributed Bragg Reflector) 9, a switchable reflector, and a switchable wave plate can also be arranged in the layered body of each self-luminous or illuminated light-emitting surface F, so that the emission of light in the first wavelength range Δλ1 can be started and interrupted.

[0078] The invention is particularly significant in that the method is used to generate a first operating state B1 for a restricted viewing mode and a second operating state B2 for a free viewing mode in a display screen whose smallest pixel corresponds to the luminous surface F according to one of the above-described method variants, wherein:

[0079] For a first operating state B1 for a restricted viewing mode, the switchable color converter 7 (if provided) is deactivated and / or the DBR (Distributed Bragg Reflector) 9, the switchable mirrors or wave plates are activated, and

[0080] For the second operating state B2 for the free-viewing mode, the switchable color converter 7 is activated and / or the DBR (Distributed Bragg Reflector) 9 , the switchable mirror or the wave plate is deactivated.

[0081] also, Figure 7 A schematic diagram showing a third embodiment of the method according to the present invention is shown. Figure 5An improved version of the second design, where the laminate includes various emission layers 4 corresponding to R, G, B (red, green, blue) so as to obtain full color from the light-emitting light-emitting surface F. Therefore, the first wavelength range Δλ1 includes red, green, and blue spectral components. In this case, the influence on the light propagation direction is achieved by (at least) one color converter 7 arranged in front of the substrate and a color filter 8 for averaging light of shorter wavelengths (i.e., the first wavelength range Δλ1). The various emission layers 4 (corresponding to red, green, and blue for R, G, B respectively) combined with the color converter 10 generate these three primary colors in the self-luminous light-emitting surface F here.

[0082] In the case of using full color as described above, two or three or even more such color converters 7 or color filters 8, each responsible for one or more peak wavelengths, can be arranged according to the design.

[0083] Finally, Figure 8 An exemplary graph showing the corresponding exemplary wavelength ranges Δλ2 and Δλ1 is shown. Again, it should be noted here that the wavelength ranges Δλ2 and Δλ1 can of course have more wavelength peaks, but these wavelength ranges must be pairwise non-overlapping.

[0084] The above-mentioned drawings can also be used in a similar way to illustrate the structure according to the present invention. To avoid redundancy, it will not be introduced here.

[0085] The method according to the present invention as described above achieves the proposed object. A method and a structure for influencing the light propagation direction have been introduced. The present invention can be particularly applicable to OLED pixels or OLED displays and can achieve operating states of free viewing and restricted viewing. In addition, the present invention can be implemented at low cost and is generally applicable to various types of displays in particular, so as to be able to switch between a protected viewing mode and a free viewing mode in such a way that the resolution of such a display is not reduced in principle.

[0086] The present invention as described above can be used in conjunction with an image display device wherever confidential data is displayed and / or input, for example when entering a PIN code or when displaying data on an automated teller machine or a payment terminal, or for entering a password or when reading an email on a mobile device. The present invention can also be applied in a passenger vehicle when the driver's attention should not be attracted by distracting images. Other application scenarios are in the fields of lighting and advertising, especially for preventing light pollution.

[0087] List of reference numerals

[0088] 1 Substrate

[0089] 2 Translucent first electrode

[0090] 3 Organic layer

[0091] 4 Emission layer

[0092] 5 Organic layer

[0093] 6 Reflector and electrode or second electrode with reflection function

[0094] 7 Color converter

[0095] 8 Color filter

[0096] 9 DBR (Distributed Bragg Reflector)

[0097] 10 Color converter

[0098] F Light emitting surface

Claims

1. A method for influencing the light propagation direction of at least one light-emitting surface (F), wherein, The light-emitting surface (F) emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a second spatial direction R2 that is different from the first spatial direction R1. The wavelength ranges Δλ1 and Δλ2 have a spectral radiant density associated with the wavelength and are different at least in terms of the peak wavelength. At least one switchable color converter (7) is arranged in front of the light-emitting surface (F) in the viewing direction. In the deactivated state, the color converter absorbs light of a shorter wavelength while transmitting light of a longer wavelength, and in the activated state, the color converter converts light of a shorter wavelength into light of a longer wavelength and transmits light of a longer wavelength. The method includes the following steps: Deactivate the color converter (7) in a first mode so as to transmit light in the second wavelength range Δλ2 and absorb light in the first wavelength range Δλ1, whereby the light emitted from the light-emitting surface (F) can only be perceived from the second spatial direction R2, or Activate the color converter (7) in a second mode so as to convert light in the first wavelength range Δλ1 into light in the second wavelength range Δλ2 and transmit light in the second wavelength range Δλ2, whereby the light emitted from the light-emitting surface (F) can be perceived from both spatial directions R1, R2.

2. The method according to claim 1, wherein The switchable color converter (7) is formed by quantum dots, where each quantum dot has a spatial extent of at most 100 nm.

3. The method according to claim 2, wherein, Each quantum dot has a spatial extent of at most 50 nm.

4. The method according to claim 3, characterized in that, Each quantum dot has a spatial extent of at most 20 nm.

5. The method according to any one of claims 1 to 4, characterized in that The switchable color converter (7) does not cover the entire light-emitting surface (F), but only covers its actual sub-region.

6. The method according to any one of claims 1 to 4, characterized in that The switchable color converter (7) is deactivated by applying an electric field and activated in the absence of an electric field.

7. The method according to any one of claims 1 to 4, characterized in that, There are provided a plurality of self-luminous light-emitting surfaces (F), each of which corresponds to the emission surface of the smallest pixel constructed as a layer body of a QLED display screen, an OLED display screen, a miniLED display screen, an LED display screen or a micro-LED display screen.

8. The method according to claim 7, characterized in that, In the layer body of such a smallest pixel, there is also provided at least one electro-optical component (9) that changes the emission characteristics of the light-emitting surface (F), and the electro-optical component is designed as a DBR (Distributed Bragg Reflector), a semi-transparent mirror, a wave plate, a liquid crystal layer, an electrochromic layer, an electro-wetting element, a switchable absorber or designed as a phase change material, such that at least in the first spatial direction R1, light in the first wavelength range Δλ1 is emitted instead of light in the second wavelength range Δλ2.

9. The method according to claim 8, wherein The electro-optical component changes the emission characteristics of the light-emitting surface (F) by changing the resonance conditions in the above-mentioned layer body.

10. A method for influencing the light propagation direction of at least one self-luminous or illuminated light-emitting surface (F), wherein, The light-emitting surface (F) selectively: in a first mode, emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a second wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a second spatial direction R2 different from the first spatial direction R1, or in a second mode, emits light in at least the second wavelength range Δλ2 in two spatial directions R1, R2, where the wavelength ranges Δλ1 and Δλ2 have a spectral radiant density associated with the wavelength and are different at least in terms of the peak wavelength. At least one color filter (8) is arranged in front of the light-emitting surface (F) along the viewing direction. The color filter absorbs light in the wavelength range Δλ1 and transmits light in the wavelength range Δλ2. The method includes the following steps: Activating the first mode, where the light in the second wavelength range Δλ2 can only be perceived from the second spatial direction R2 after passing through the color filter (8), or Activating the second mode, where the light in the second wavelength range Δλ2 can be perceived from both spatial directions R1, R2 after passing through the color filter (8).

11. The method according to claim 10, wherein There are a plurality of self-luminous light-emitting surfaces (F), and each of the self-luminous light-emitting surfaces corresponds to the emission surface of the smallest pixel constructed as a layer body of a QLED display screen, an OLED display screen, a miniLED display screen, an LED display screen, or a micro-LED display screen.

12. The method according to claim 11, wherein In the layer body arranged below each light-emitting surface (F), at least one electro-optical component (9) is further provided. The electro-optical component changes the resonance conditions in the layer body, and the electro-optical component is designed as a DBR (Distributed Bragg Reflector), a semi-transparent mirror, a wave plate, a liquid crystal layer, an electrochromic layer, an electro-wetting element, a switchable absorber, or is designed as a phase change material, such that: it is possible to switch between emitting light in the first wavelength range Δλ1 and emitting light in the second wavelength range Δλ2 in the spatial direction R1.

13. The method according to any one of claims 10 to 12, characterized in that, For full-color gamut display, for each of the three primary colors of red, green, and blue, at least a pair of internal wavelength ranges within the first wavelength range Δλ1 and the second wavelength range Δλ2 are provided, where for each pair of internal wavelength ranges with two peaks in the spectrum differing by several nanometers to 200 nm, one peak is correspondingly located in the first wavelength range Δλ1 and one peak is located in the second wavelength range Δλ2.

14. Use of a method according to any one of claims 1 to 9 for generating a first operating state B1 for a restricted viewing mode and a second operating state B2 for a free viewing mode in a display screen, wherein The smallest pixel of the display screen has an electro-optical component (9) and a light-emitting surface (F). The switchable color converter (7) is deactivated to generate the first operating state B1, and the switchable color converter (7) is activated to generate the second operating state B2.

15. A structure for influencing the light propagation direction of at least one light-emitting surface (F), wherein, The light-emitting surface (F) emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a second wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a second spatial direction R2 that is different from the first spatial direction R1, where the wavelength ranges Δλ1 and Δλ2 have a spectral radiance density associated with the wavelength and are different at least in terms of the peak wavelength. The structure further includes at least one switchable color converter (7) arranged in front of the light-emitting surface (F) along the viewing direction. The color converter absorbs light of a shorter wavelength and simultaneously transmits light of a longer wavelength in the deactivated state, and the color converter converts light of a shorter wavelength into light of a longer wavelength and transmits it in the activated state. The color converter (7) is deactivated in a first mode such that light in the second wavelength range Δλ2 is transmitted while light in the first wavelength range Δλ1 is absorbed, whereby the light emitted from the light-emitting surface (F) can only be perceived from the second spatial direction R2, and The color converter (7) is activated in a second mode such that light in the first wavelength range Δλ1 is at least partially converted into light in the second wavelength range Δλ2, and light in the second wavelength range Δλ2 is transmitted, whereby the light emitted from the light-emitting surface (F) can be perceived from both spatial directions R1 and R2.

16. The structure according to claim 15, wherein, The switchable color converter (7) includes quantum dots.

17. A structure for influencing the light propagation direction of at least one light-emitting surface (F), where The light-emitting surface (F) selectively: in a first mode, emits light in a first wavelength range Δλ1 in a first spatial direction R1 and emits light in a second wavelength range Δλ2 that is at least partially different from the first wavelength range Δλ1 in a second spatial direction R2 that is different from the first spatial direction R1, or in a second mode, emits light in at least the second wavelength range Δλ2 in both spatial directions R1 and R2, where the wavelength ranges Δλ1 and Δλ2 have a spectral radiance density associated with the wavelength and are different at least in terms of the peak wavelength. The structure further includes at least one color filter (8) arranged in front of the light-emitting surface (F) along the viewing direction. The color filter absorbs light in the wavelength range Δλ1 and transmits light in the wavelength range Δλ2, where Activate the first mode, where the light in the second wavelength range Δλ2 can only be perceived from the second spatial direction R2 after passing through the color filter (8), or Activate the second mode, where the light in the second wavelength range Δλ2 can be perceived from both spatial directions R1 and R2 after passing through the color filter (8).

18. The structure according to claim 17, wherein, There are provided a plurality of self-luminous light-emitting surfaces (F), and each of the plurality of self-luminous light-emitting surfaces corresponds to the emission surface of the smallest pixel having a layered structure in a QLED display screen, an OLED display screen, a miniLED display screen, an LED display screen, or a micro-LED display screen.

19. The structure according to claim 18, wherein, In a layer body arranged below each light-emitting surface (F), there is further provided at least one electro-optical component (9), which changes the resonance conditions in the layer body, and the electro-optical component is designed as a DBR (Distributed Bragg Reflector), a semi-transparent mirror, a wave plate, a liquid crystal layer, an electrochromic layer, an electro-wetting element, a switchable absorber or is designed as a phase change material, such that: the emission of light in a wavelength range Δλ1 can be started and interrupted.

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