Display, method for operating a display and method for manufacturing a plurality of micro optic elements

Abstract

A display with a plurality of pixels (1) is provided, wherein - each pixel (1) has a first set of at least two sub-pixels (2) and a second set of at least two sub-pixels (3), - each sub-pixel (R, G, B) comprises a micro-LED (5) emitting electromagnetic radiation during operation, and - micro optic elements (4) are arranged above the micro-LEDs (5) of the second set of sub-pixels (3), the micro optic elements (4) collimating beam cones (6) of the electromagnetic radiation of the micro-LEDs (5) of the second set of sub-pixels (3). Further a method for operating a display and a method for manufacturing a plurality of micro optic elements, particularly for a display, are provided.

Description

[0001] Description

[0002] DISPLAY, METHOD FOR OPERATING A DISPLAY AND METHOD FOR MANUFACTURING A PLURALITY OF MICRO OPTIC ELEMENTS

[0003] A display, a method for operating a display and a method for manufacturing a plurality of micro optic elements , particularly for a display, are provided .

[0004] An improved display and an improved method for operating a display are to be provided . Moreover, a simpli fied method for manufacturing a plurality of micro optic elements , particularly for a display, is to be provided .

[0005] These obj ects are achieved by a display with the features of claim 1 , by a method for operating a display with the steps of claim 14 and by a method for manufacturing a plurality of micro optic elements with the steps of claim 18 .

[0006] Improved embodiments and developments of the display, the method for operating a display and the method for manufacturing a plurality of micro optic elements are given in the respective dependent claims .

[0007] According to an embodiment , the display comprises a plurality of pixels . Particularly, the pixels are image points for representation of an image by the display . For example , some or all pixels of the display are embodied in the same or in a di f ferent manner .

[0008] According to an embodiment of the display, each pixel has a first set of at least two sub-pixels and a second set of at least two sub-pixels . Particularly, the first set of sub- pixels and the second set of sub-pixels have the same number of sub-pixels . For example , the first set has three subpixels and the second set has three sub-pixels . For example , the first set has a red sub-pixel , a green sub-pixel and a blue sub-pixel and the second set has a red sub-pixel , a green sub-pixel and a blue sub-pixel . Particularly, the subpixels of the first set and / or sub-pixels of the second set di f fer in the color of light emitted by the sub-pixel .

[0009] According to a further embodiment of the display, each subpixel comprises a micro-LED emitting electromagnetic radiation during operation . Particularly, the micro-LED emits electromagnetic radiation of the color of the respective suppixel . The micro-LED comprises an epitaxial layer stack with an active zone generating the electromagnetic radiation emitted by micro-LED from a light exit surface during operation .

[0010] As a broad definition, a micro-LED could be seen as any light emitting diode ( LED) - generally not a laser - with a particularly small si ze .

[0011] As a rule - and this is a very important criterion in addition to the si ze - a growth substrate of the epitaxial layer stack is removed from the micro-LED, so that a typical height of the micro-LED is , for example , in the range of 0 . 5 micrometer to 10 micrometer, limits included or in the range of 1 . 5 micrometer to 10 micrometer, limits included . In that case , the micro-LED is , in particular, free of a carrier mechanically stabili zing the epitaxial layer stack of the micro-LED . For example , a micro-LED has a rectangular light exit surface . It is also possible that the light exit surface of the micro-LED has a di f ferent geometry .

[0012] For example , the micro-LED has a light exit surface wherein, in plan view of the epitaxial layer stack, any lateral extent of the light exit surface is less than or equal to 100 micrometer or less than or equal to 70 micrometer . Particularly, a plurality of micro-LEDs is provided on a carrier wafer, wherein the micro-LEDs are connected to the carrier wafer with detachable holding structures . The micro- LEDs can be removed from the carrier wafer by detaching the holding structures and trans ferred to a further element , such as a back plate of a display .

[0013] In particular, the micro-LEDs are used in the display . The micro-LEDs are part of the sub-pixels and emit light of a defined color . Their small si ze and the possibility to arrange them in a high density with close distances , for example on a back plate of display, make the micro-LEDs suitable , among others , for small monolithic displays for augmented reality applications , especially for data glasses . In addition, other applications are being developed, in particular regarding the use in data communication or pixelated lighting applications .

[0014] Di f ferent ways of spelling micro-LED, e . g . pLED, p-LED, uLED, u-LED or micro light emitting diode can be found in the relevant literature .

[0015] According to a further embodiment of the display, micro optic elements are arranged above the micro-LEDs of the second set of sub-pixels , the micro optic elements collimating beam cones of the electromagnetic radiation emitted by the microLEDs of the second set of sub-pixels . For example , the micro optic elements are arranged down-stream of the second set of sub-pixels in a radiation direction of the second set of subpixels . Particularly, the micro optic elements reduce aperture angles of the beam cones of the electromagnetic radiation of the micro-LEDs . Particularly, the micro optic elements are embodied in the same or a di f ferent manner . For example , the micro optic elements arranged within the beam cones of micro-LEDs of sub-pixels emitting electromagnetic radiation of the same color are embodied in the same manner .

[0016] It is an idea of the present application to provide each pixel with two sets of sub-pixels , the two sets of sub-pixels are configured to be operated independently from each other . Particularly, with the help of the micro optic elements above the second set of sub-pixels a privacy operation mode can be embodied within the display . During the privacy operation mode , only the micro-LEDs of the second set of the at least two sub-pixels are switched on . In the privacy operation mode , a beam cone of the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels is reduced such that a viewing angle from the environment of the display is small . Particularly, it is not necessary to add a condenser foil to the display to generate a privacy operation mode . Particularly, in the privacy operation mode only the user of the display and no further persons near the user can identi fy the content of the display .

[0017] According to a further embodiment of the display, beam cones of the electromagnetic radiation of the sub-pixels of the first set of sub-pixels are not collimated, particularly by further micro optic elements . In particular, no collimating optical elements are arranged between the micro-LEDs of the first set of sub-pixels and an emission surface of the display . In other words , the electromagnetic radiation of the sub-pixels of the first sets of sub-pixels is not collimated by any optics , while the electromagnetic radiation emitted by the micro-LEDs of the second set of sub-pixels is collimated by the micro optic elements for operating the display in the privacy operation mode .

[0018] According to a further embodiment of the display, the beam cones of the electromagnetic radiation of the micro-LEDs of the first set of sub-pixels have an aperture angle larger than an aperture angle of the beam cones of the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels at an emission surface of the display . In other words , i f seen in plan view on the emission surface of the display, light spots generated by the electromagnetic radiation of the micro-LEDs of the first set of sub-pixels have a greater diameter than light spots generated by the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels at the emission surface .

[0019] According to a further embodiment of the display, the micro optic elements are attached to the micro-LEDs of the second set of sub-pixels , particularly directly . In other words , a micro optic element is attached to each micro-LED of the second set of sub-pixels , for example . Particularly, in this embodiment , the micro-LEDs of the first set of sub-pixels are free of micro optic elements , while the micro optic elements are attached to the micro-LEDs of the second set of subpixels such that the electromagnetic radiation of the micro- LEDs of the second set of sub-pixels runs through the micro optic elements . Particularly, beam cones of the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels are larger before entering the micro optic elements than after exiting the micro optic elements .

[0020] According to a further embodiment of the display, the micro optic elements are part of a movable micro optic array arranged over the micro-LEDs of the second set of sub-pixels . For example , the micro optic elements are part of a movable plate , wherein the movable plate mechanically connects and integrates all of the micro optic elements of the display to the micro optic array . Particularly, the parts of the plate through which the electromagnetic radiation of the micro-LEDs of the first set of sub-pixels runs through do not collimated the electromagnetic radiation of the micro-LEDs of the first set of sub-pixels .

[0021] According to a further embodiment of the display, at least the micro-LEDs of the second set of sub-pixels are arranged within cavities of a substrate . For example , the substrate is a silicon substrate or a silicon back plate of a display . Particularly, the substrate comprises a plurality of cavities and each micro-LED of the second set of sub-pixels is arranged in a separate cavity . Particularly, the cavities have sloped side faces . For example , the sloped side face encloses an angle between and including 30 ° and 60 ° with a normal of a bottom face of the cavity . Particularly, the cavities act as reflectors for the electromagnetic radiation emitted by the micro-LEDs of the second set of sub-pixels . Particularly, electromagnetic radiation emitted from a side face of the micro-LED arranged within the cavity impinge on the side face of the cavity and is redirected to the emission surface of the display . With the help of the cavities , a first step of collimation of the electromagnetic radiation emitted by the micro-LEDs is performed on the substrate level .

[0022] It is also possible that the micro-LEDs of the first set of sub-pixels are , additionally or alternatively, arranged within the cavities of a substrate . In other words , it is possible that only the micro-LEDs of the first set of subpixels are arranged within the cavities of the substrate and the micro-LEDs of the second set of sub-pixels are arranged on a planar main surface of the substrate . Further, it is possible that only the micro-LEDs of the second set of subpixels are arranged within the cavities of the substrate and the micro-LEDs of the first set of sub-pixels are arranged on a planar main surface of the substrate .

[0023] It is also possible that the micro-LEDs of the first set of sub-pixels and the micro-LEDs of the second set of sub-pixels are arranged on the planar main surface of the substrate . In other words , it is possible that the substrate is free of cavities and that the micro-LEDs are arranged on the planar main surface of the substrate .

[0024] According to a further embodiment of the display, the side faces of the cavities are covered with mirror layers . Particularly, the mirror layers specularly reflect the electromagnetic radiation of the micro-LEDs arranged within the cavities . Particularly, the mirror layers comprise or consist of a metal . For example , the mirror layers act also as a bottom contact electrode for the micro-LEDs of the second set of sub-pixels arranged within the cavities .

[0025] According to a further embodiment of the display, the cavities are filled with a dielectric material , particularly completely . Particularly, the cavities are filled with a non- conductive material being transparent for the electromagnetic radiation of the micro-LEDs placed within the cavities . For example , the cavities are filled with an oxide and / or a nitride , such as silicon oxide and / or silicon nitride .

[0026] According to a further embodiment of the display, the cavities are covered with a transparent electrode , particularly being in direct contact with the micro-LEDs arranged within the cavities . Particularly, the micro-LEDs are electrically conductively connected to the transparent electrode . The transparent electrode is particularly transparent for the electromagnetic radiation emitted by the micro-LEDs arranged within the cavities . For example , the transparent electrode comprises or consists of a TCO ( short for "transparent conductive oxide" ) , such as ITO ( short for " indium tin oxide" ) .

[0027] According to a further embodiment of the display, the micro optic elements comprise TIR-lenses ( TIR short for "total internal reflection" ) . Particularly, a single micro optic element comprises or consists of a TIR-lens .

[0028] For example , the TIR-lens comprises a high refractive region and a low refractive region . The high refractive region has a high refractive index for the electromagnetic radiation emitted by the micro-LEDs , while the low refractive region has a low refractive index for the electromagnetic radiation of the micro-LEDs . For example , the low refractive region has a refractive index between and including 1 . 2 and 1 . 4 for the electromagnetic radiation of the micro-LEDs , while the high refractive region has a refractive index between and including 1 . 6 and 1 . 8 for the electromagnetic radiation of the micro-LEDs . Preferably, a di f ference of the refractive indices of the low refractive region and the high refractive region is at least 0 . 4 .

[0029] For example , the low refractive region surrounds the high refractive region, particularly completely in a lateral direction . Particularly, the low refractive region is in direct contact with the high refractive region such that an interface is formed between the low refractive region and the high refractive region . The interface of the high refractive region and the low refractive region is configured for total internal reflection of the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels . Particularly, electromagnetic radiation of the micro-LEDs does not leave the micro optic elements at their side faces . For example , the interface of the high refractive region and the low refractive region is a free form surface .

[0030] Collimation of the electromagnetic radiation takes place due to total internal reflection of the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels at the interface of the high refractive region and the low refractive region .

[0031] For example , the high refractive region is configured as a lens element , particularly as a collimating lens element . Further, the high refractive region comprises a light exit surface of the TIR-lens . The light exit surface of the TIR- lens is , for example , a free form surface .

[0032] According to an embodiment , the display further comprises a 3D-sensor and / or a camera configured to detect an obj ect in the environment of the display . For example , the 3D-sensor is a time-of- f light sensor, such as a direct time-of- f light sensor or an indirect time-of- f light sensor . For example , the 3D-sensor and / or the camera are configured to detect a user of the display . For example , the 3D-sensor and / or the camera detect the eyes of the user of the display .

[0033] According to an embodiment , the display further comprises an actuator configured to move the micro optic elements during operation in a shi fting operation mode . For example , the actuator comprises or consists of a voice coil motor ( short : VCM) or a shape memory alloy ( short : SMA) . Particularly, the actuator moves the micro optic elements such that , in a privacy operation mode , wherein a viewing angle of the display is very narrow, the eyes of the user can be tracked and the micro optic elements can be moved accordingly in order not to lose the image shown by the display for a user in a tracking operation mode . For example , the eyes of the user are tracked with the camera or the 3D-sensor and the micro optic elements are moved accordingly by the actuator .

[0034] For example , the micro optic elements are part of a micro optic array arranged over the micro-LEDs of the second set of sub-pixels . In that case , the actuator is configured to move the micro optic array depending on the obj ect detected by the 3D-sensor and / or the camera in the tracking operation mode .

[0035] Particularly, the beam cones of the electromagnetic radiation emitted by the micro-LEDs of the second set of sub-pixels are tilted by the movement by the actuator, for example in order to follow up the eyes of the user . Particularly, by shi fting the micro optic elements with respect to the micro-LEDs , the beam cones of the electromagnetic radiation collimated by the micro-LEDs is tilted with respect to a normal of the emission surface of the display . This ef fect is used to guide the electromagnetic radiation of the micro-LEDs of the second set of sub-pixels towards the user .

[0036] I f the micro optic elements are part of a micro optic array, for example , by integration in the plate , the micro optic elements are connected to each other and shi fted by the actuator simultaneously to tilt all beam cones of the electromagnetic radiation of the micro-LRDs of the second set of sub-pixels in the same way . For example , the plate is shi fted in an x-direction and in an y-direction in an XY- plane and all possible combinations from x and y in the XY- plane can be taken . Consequently, the beam cones are tilted in all possible polar directions within a certain range .

[0037] According to a further embodiment of the display, the subpixels of a pixel are arranged in a diagonal of the pixel . Particularly, the sub-pixels of the first set of sub-pixels and the sub-pixels of the second set of sub-pixels are arranged in a common diagonal of the pixel . Particularly, this configuration of the sub-pixels makes it possible to operate the display in a high resolution operation mode with double resolution by driving both sets of sub-pixels , particularly the first set of sub-pixels and the second set of sub-pixels , simultaneously .

[0038] It is also possible that the sub-pixels of a pixel are arranged in columns and rows of the pixel . Particularly, the sub-pixels of the first set of sub-pixels and the sub-pixels of the second set of sub-pixels are arranged in columns and rows of the pixel . The display described herein can be operated with the method described in the following . Therefore , features and embodiments described in connection with the display can also be embodied within the method for operating the display, and vice versa .

[0039] According to an embodiment of the method for operating a display having a plurality of pixels , each pixel has a first set of at least two sub-pixels and a second set of at least two sub-pixels and each sub-pixel comprises a micro-LED emitting electromagnetic radiation during operation, wherein micro optic elements collimate beam cones of the electromagnetic radiation of the micro-LEDs .

[0040] According to a further embodiment of the method, the micro- LEDs of the first set of sub-pixels and / or the micro-LEDs of the second set of sub-pixels are switched on . For example , only the micro-LEDs of the first set of sub-pixels are switched on and the micro-LEDs of the second set of subpixels are switched of f in a normal operation mode or only the micro-LEDs of the second set of sub-pixels are switched on and the micro-LEDs of the first set of sub-pixels are switched of f in a privacy operation mode .

[0041] I f the micro-LEDs of the first set of sub-pixels are switched of f and the micro-LEDs of the second set of sub-pixels are switched on, the display is operated in the privacy operation mode , wherein a viewing angle of the display from the environment is reduced compared to the normal operation mode .

[0042] Since the display intensity is distributed over a smaller angle due to the collimation of the micro-LEDs of the second set of sub-pixels less power is used for the same brightness of the display in the privacy operation mode than in the normal operation mode . Therefore , the privacy operation mode is also a power saving operation mode . Since the display is often by far the most power-consuming element , for example , in a smartphone , the power-saving ef fect of the privacy operation mode is signi ficant .

[0043] I f both, the micro-LEDs of the first set of sub-pixels and the micro-LEDs of the second set of sub-pixels are switched on, the display is operated in a high resolution operation mode . Particularly, the resolution of the display in the high resolution operation mode is twice compared to resolution of the display operated in the privacy operation mode or in the normal operation mode .

[0044] According to a further embodiment of the method, beam cones of the micro-LEDs of the second set of sub-pixels are tilted with respect to a normal of an emissions surface of the display in a shi fting operation modes by shi fting the micro optic elements when the micro-LEDs of the second set of subpixels are switched on . For example , shi fting takes place by an actuator . Particularly, in the shi fting operation mode the first set of sub-pixels is switched of f . Particularly, shi fting of the micro optic elements takes place in an XY- plane extending along a main extension plane of the display . By shi fting the micro optic elements in the XY-plane , the beam cones of the electromagnetic radiation emitted by the micro-LEDs of the second set of sub-pixels are tilted with respect to the normal of the emission surface of the display .

[0045] According to a further embodiment of the method, the micro optic elements are shi fted such that a resolution of the display is enhanced by a factor of four compared to the resolution of the display operated in the privacy operation mode or the normal operation mode . Particularly, an image of a pixel is shi fted by a distance of hal f the pixel rotating around a center of the pixel . This operation mode is also called super resolution operation mode at present .

[0046] According to a further embodiment of the method, a location of an obj ect in the environment of the display is detected, for example by a camera or a 3D-sensor . According to a further embodiment of the method, the micro optic elements are shi fted depending on the detected location of the obj ect . During this embodiment of the method, the first set of subpixels is particularly switched of f . With this operation mode the eyes of a user are detected and the micro optic elements are moved accordingly in order not to lose the image shown by the display, for example . This operation mode is , at present , called tracking operation mode .

[0047] The micro optic elements described in connection with the display can, for example , be manufactured with the method described in the following . Features and embodiments described in connection with the micro optic elements can therefore be also embodied in the method and vice versa .

[0048] According to an embodiment of the method for manufacturing a plurality of micro optic elements , particularly for a display, a carrier is provided .

[0049] According to a further embodiment of the method, a layer of a low refractive resin is applied on the carrier . Particularly, the layer of the low refractive resin is applied to the carrier in a liquid and / or uncured form . Particularly, the low refractive resin is photo-curable . It is also possible that the low refractive resin is curable with the help of a catalyst or the impact of heat .

[0050] According to a further embodiment of the method, the layer of the low refractive resin is structured, for example with the help of a tool . For example , structuring of the layer of the low refractive resin is done by an imprinting method with the help of a tool . After structuring, the layer of the low refractive resin is cured, in particular .

[0051] According to a further embodiment of the method, a layer of a high refractive resin is applied on the structured layer of the low refractive resin, particularly after curing the structured layer of the low refractive resin . Particularly, the layer of the high refractive resin completely fills the structures inserted in the layer of the low refractive resin during structuring . Particularly, the layer of the high refractive resin is applied in an uncured manner on the low refractive resin .

[0052] According to a further embodiment of the method, the layer of the high refractive resin is structured after application to the layer of the low refractive resin . After structuring, the layer of the high refractive resin is preferably cured, for example by the help of electromagnetic radiation .

[0053] Also , the layer of the high refractive resin can be structured by the help of a tool . For example , structuring of the layer of the high refractive resin is done by an imprinting method .

[0054] According to a further embodiment of the method, the resin compound on the carrier is separated, for example by trench etching or dicing, such that micro optic elements are generated on the carrier .

[0055] Particularly, the method for manufacturing a plurality of micro optic elements is a mass production process , wherein a plurality of micro optic elements are manufactured in parallel . The micro optic elements can be trans ferred to other elements such as the micro-LEDs of the sub-pixels , for example in a mass trans fer process . Further, it is possible to use the micro-LEDs as a carrier and to produce the micro optic elements directly on the micro-LEDs .

[0056] Further advantageous embodiments and developments of the display, the method for operating a display and the method for manufacturing a plurality of micro optic elements , particularly for a display, become apparent from the exemplary embodiment described below in connection with the Figures .

[0057] Figure 1 schematically shows a display according to an exemplary embodiment .

[0058] Figures 2 and 3 each schematically show a set of sub-pixels of the display of Figure 1 .

[0059] Figures 4 and 5 schematically show a display operated in an operation mode according to an exemplary embodiment .

[0060] Figures 6 and 7 schematically show a display operated in an operation mode according to a further exemplary embodiment .

[0061] Figures 8 and 9 schematically show a display operated in an operation mode according to a further exemplary embodiment . Figure 10 schematically shows a display according to a further exemplary embodiment .

[0062] Figures 11 to 12 schematically show a pixel of the display of Figure 10 .

[0063] Figure 13 schematically shows a display operated in an operation mode according to a further exemplary embodiment .

[0064] Figures 14 to 16 schematically show a display operated in an operation mode according to a further exemplary embodiment .

[0065] Figures 17 to 19 schematically show a display operated in an operation mode according to a further exemplary embodiment .

[0066] Figure 20 schematically shows a display according to a further exemplary embodiment .

[0067] Figures 21 and 22 schematically show a set of sub-pixels of a pixel of a display operated in an operation mode according to a further exemplary embodiment .

[0068] Figures 23A to 23D schematically show a pixel of a display operated in an operation mode according to a further exemplary embodiment .

[0069] Figures 24 and 25 schematically show a sub-pixel of a pixel of a display according to a further exemplary embodiment .

[0070] Figures 26 and 27 schematically show sub-pixels of a pixel of a display according to further exemplary embodiments . Figure 28 schematically shows a display according to a further embodiment .

[0071] Figure 29 schematically shows a display operated in an operation mode according to a further exemplary embodiment

[0072] Figures 30 to 36 schematically show stages of a method for manufacturing a plurality of micro optic elements , particularly for a display .

[0073] Equal or similar elements as well as elements of equal function are designated with the same reference signs in the Figures . The Figures and the proportions of the elements shown in the Figures are not regarded as being shown to scale . Rather, single elements , in particular layers , can be shown exaggerated in magnitude for the sake of better presentation and / or better understanding .

[0074] The display according to the exemplary embodiment of Figures 1 to 3 comprises a plurality of pixels 1 . Figure 1 shows exemplarily an excerpt of four pixels 1 . Each pixel 1 comprises a first set of sub-pixels 2 and a second set of sub-pixels 3 . Each sub-pixel comprises a micro-LED 5 emitting electromagnetic radiation during operation .

[0075] According to the present exemplary embodiment , each set of sub-pixels 2 , 3 , comprises three sub-pixels , each sub-pixel comprising a micro-LED 5 as light source . Particularly, each set of sub-pixels 2 , 3 comprises a micro-LED 5 emitting red light of a red sub-pixel R, a micro-LED 5 emitting green light of a green sub-pixel G and a micro-LED 5 emitting blue light of a blue sub-pixel B . The sub-pixels R, G, B of the pixels 1 are arranged in rows and columns . Particularly, the sub-pixels R, G, B of the first set of sub-pixels 2 are arranged in a common row and the sub-pixels R, G, B of the second set of sub-pixels 3 are arranged in a common row .

[0076] Further, the display comprises micro optic elements 4 arranged subsequently in a radiation direction of the microLEDs 5 of the second set of sub-pixels 3 . The micro optic elements 5 collimate beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 . The electromagnetic radiation of the first set of sub-pixels 2 is not collimated by optical elements and impinges in a non-collimated manner on an emission surface 7 of the display .

[0077] Figure 2 shows schematically the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the first set of sub-pixels 2 , while Figure 3 shows schematically the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 being collimated by micro optic elements 4 . The beam cones 6 of the micro-LEDs 5 of the first set of sub-pixels 2 have apertures angles cti being larger than apertures angles ot.2 of the beam cones 6 of the electromagnetic radiation of the second set of sub-pixels 3 being collimated by the micro optic elements 4 .

[0078] Figures 4 and 5 show the display of Figures 1 to 3 in an operation mode according to an exemplary embodiment . Particularly, Figures 4 and 5 illustrate a normal operation mode of the display . During the normal operation mode , the micro-LEDs 5 of the first set of sub-pixels 2 of each pixel 1 are switched on such that the electromagnetic radiation of the micro-LEDs 5 of the first set of sub-pixels 2 impinges in an uncollimated manner on an emission surface 7 of the display . The micro-LEDs 5 of the second set of sub-pixels 3 are switched of f during the normal operation mode . The second set of sub-pixels 3 and particularly the micro-LEDs 5 of the second set of sub-pixels 3 together with the micro optic elements 4 arranged above the micro-LEDs 5 are schematically shown in Figure 4 . In the figure , the second set of subpixels 3 is arranged laterally to the first set of sub-pixels

[0079] 2 for the purpose of illustration . However, as shown in Figure 1 as well as in Figure 5 , the second set of sub-pixels

[0080] 3 and the first set of sub-pixels 1 are arranged in two di f ferent rows .

[0081] Figure 5 shows a plan view on the emission surface 7 of the display of Figure 4 in a schematic manner . Particularly, seen in plan view on the emission surface 7 , the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the first set of sub-pixels 2 form light spots 8 overlapping with each other and having a first diameter dl . The micro- LEDs 5 of the second set of sub-pixels 3 are switched of f and do not contribute to the brightness of the display .

[0082] Figures 6 and 7 show the display of Figures 1 to 3 in an operation mode according to a further exemplary embodiment . Particularly, Figures 6 and 7 illustrate a privacy operation mode of the display . In the privacy operation mode , only the micro-LEDs 5 of the second set of sub-pixels 3 are switched on, while the micro-LEDs 5 of the first set of sub-pixels 2 are switched of f . The electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 is collimated by micro optic elements 4 such that an aperture angle ot.2 of the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 is reduced, compared to the aperture angle cti of the beam cones 6 of the electromagnetic radiation emitted by the first set of sub-pixels 2 .

[0083] Again, the first set of sub-pixels 2 is schematically shown in Figure 6 laterally arranged next to the second set of subpixels 3 for the sake of illustration . As , for example , can be seen in Figure 7 , the first set of sub-pixels 2 and the second set of sub-pixels 3 are arranged in rows and columns .

[0084] As can be seen in Figure 7 , showing a plan view on the emission surface of the display, light spots 8 of the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 have a smaller second diameter d2 than the light spots 8 of the beam cones 6 of the electromagnetic radiation emitted by the first set of sub-pixels 2 ( compare Figure 5 ) .

[0085] Further, a viewing angle from the environment on the emission surface 7 of the display is reduced due to the reduced aperture angle 0C2 of the micro-LEDs 5 illuminating the emission surface 7 . In such a way, a privacy operation mode is reali zed without adding a condenser foil or another optical foil to the emission surface 7 of the display .

[0086] Further, the privacy operation mode is also a battery-saving operation mode , since less power is needed to illuminate the emission surface 7 in order to achieve a speci fic brightness of the display, since the light of the micro-LEDs 5 irradiating the emission surface is collimated .

[0087] Figures 8 and 9 illustrate a further operation mode of the display according to the exemplary embodiment of Figures 1 to 3 . Particularly, Figures 8 and 9 illustrate a high resolution operation mode of the display .

[0088] During the high resolution mode , all micro-LEDs 5 of both, the first set of sub-pixels 2 and the second set of subpixels 3 are switched on . Due to the double amount of subpixels of each pixel 1 compared to the privacy operation mode and the normal operation mode , double resolution is achieved .

[0089] Compared to the display according to the exemplary embodiment of Figures 1 to 3 , the sub-pixels of a pixel 1 of the display according to the exemplary embodiment of Figures 10 to 12 are arranged on a common diagonal D of the pixel 1 ( Figure 10 ) .

[0090] A single pixel 1 is , for example , schematically shown in Figure 11 . The second set of sub-pixels 3 is again provided with micro optic elements 4 collimating the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 .

[0091] As , for example , shown in Figure 12 , the micro-LEDs 5 of the first set of sub-pixels 2 and the second set of sub-pixels 3 of a pixel 1 arranged in the common diagonal D can be electrically contacted by a grid of conductor tracks 9 . For example , the conductor tracks 9 extend over a back plate of the display and electrically contact all sub-pixels of the display at once .

[0092] For example , the display according to the exemplary embodiment of Figures 10 to 12 can be operated in a high resolution operation mode , achieving double resolution compared to a normal operation mode or a privacy operation mode , as already explained in connection with Figures 4 to 9 . In the high resolution operation mode all sub-pixels of a pixel 1 are switched on ( Figure 13 ) .

[0093] Figures 14 , 15 and 16 illustrate a further operation mode of the display according to the exemplary embodiment of Figures 10 to 12 . The display is operated in a normal operation mode , wherein the micro-LEDs 5 of a first set of sub-pixels 2 are switched on and illuminate an emission surface 7 of the display in an uncollimated manner . The micro-LEDs 5 of the second set of sub-pixels 3 provided with micro optic elements 4 for collimation of beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 are switched of f .

[0094] Figures 17 , 18 and 19 illustrate a further operation mode of the display according to the exemplary embodiment of Figures 10 to 12 . The display is operated in a privacy operation mode , wherein only the micro-LEDs 5 of the second set of subpixels 3 are switched on . The electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 is collimated by micro optic elements 4 . Due to the micro optic elements 4 , an aperture angle ot.2 of the beam cones 6 of the electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 is reduced ( Figure 19 ) .

[0095] Compared to the display of the exemplary embodiment of Figures 1 to 3 , the display according to the exemplary embodiment of Figure 20 has a plate 23 comprising the micro optic elements 4 . In other words , the micro optic elements 4 are integrated in a micro optic array 24 by the plate 23 . Particularly, the plate 23 is transparent for the electromagnetic radiation of the micro-LEDs 5 of the display . In the regions outside the micro optic elements 4 , the plate 23 is planar and does not comprise any further optics .

[0096] The plate 23 , together with the micro optic elements 4 , can be moved in a XY-plane with the use of two actuators 25 . For example , the actuators 25 comprise a voice coil motor or a shape memory alloy . By a linear combination of X shi ft and Y shi ft , all positions in the XY plane can be achieved .

[0097] The display further comprises a 3D-sensor 26 and / or a camera 27 configured for detecting an obj ect in the environment of the display .

[0098] For example , the display is operated in a privacy operation mode , wherein only the micro-LEDs 5 of the second set of subpixels 3 are switched on . The electromagnetic radiation emitted by the micro-LEDs 5 of the second set of sub-pixels 3 is collimated by the micro optic elements 4 . Therefore , a viewing angle of a user in the environment of the display is lowered compared to a viewing angle in a normal operation mode of the display, wherein only the micro-LEDs 5 of the first set of sub-pixels 1 illuminate an emission surface 7 of the display in a non-collimated manner .

[0099] In a tracking operation mode , the 3D-sensor 26 and / or the camera 27 tracks the eyes of the user of the display and the actuators 25 correspondingly shi ft the micro optic array 24 in order to track the user' s eyes such that the user does not lose the image shown by the display . However, viewers other than the user are excluded from the image shown by the display, due to the limited opening angle ot.2 of the beam cones 6 of the electromagnetic radiation illuminating the emission surface 7 of the display . In the operation mode according to the exemplary embodiment illustrated in Figures 21 , 22 and 23A to 23D, the micro optic elements are also integrated in a micro optic array 24 , as already explained in connection with Figure 20 . As exemplarily shown in Figure 21 , the micro-LEDs 5 of the second set of sub-pixels 3 is switched on and emit electromagnetic radiation of red light , green light and blue light . The electromagnetic radiation emitted by the micro- LEDs 5 of the second set of sub-pixels 3 is collimated by micro optic elements 4 integrated within a micro optic array 24 ( Figure 21 ) .

[0100] As schematically shown in Figure 22 , by shi fting the micro optic array 24 in X-direction, the beam cones 6 of the electromagnetic radiation of the micro-LEDs are tilted by an angle 0 with respect to a normal of an emission surface 7 of the display .

[0101] As explained in connection with Figures 23A to 23D, the tilting of the beam cones 6 by the angle 0 can be used to achieve a super resolution operation mode having a resolution that is four times higher than in the normal operation mode or the privacy operation mode .

[0102] Figure 23A shows the image 28 of a single pixel 1 . During operation time t , the micro optic elements 4 are shi fted such that the image 28 of the pixel 1 is shi fted . First , the image 28 of the pixel 1 is shi fted in x-direction by a distance of hal f of the pixel ( Figure 23B ) . In a further step, the image 28 of the pixel 1 is again shi fted by hal f of the width of the pixel 1 in the negative y-direction ( Figure 23C ) . Then, the image 28 of the pixel 1 is shi fted by hal f of the pixel width in the negative x-direction ( Figure 23D) . Further, the display proj ects the respective image 28 in a frame with an image refresh rate of four times of the final super resolution frame rate . Thus , the resolution is increased by a factor of four compared to the resolution of the display in the privacy operation mode and / or the normal operation mode .

[0103] The sub-pixel R of the exemplary embodiment of Figures 24 and 25 comprises a substrate 10 , for example a silicon back plate , with a cavity 12 . A micro-LED 5 is arranged on a bottom face 15 of the cavity 12 . Further, the bottom face 15 of the cavity 12 and a side face 14 of the cavity 12 surrounding the bottom face 15 are covered with a mirror layer 11 being specularly reflective for the electromagnetic radiation emitted by the micro-LED 5 arranged within the cavity 12 . The mirror layer 11 comprises or consists of a metal . The micro-LED 5 is electrically contacted by the mirror layer 11 .

[0104] Further, the cavity 12 is filled with a dielectric material 13 such as an oxide or a nitride . An opening 29 of the cavity 12 is flush with an upper face of the micro-LED 5 . The upper face of the micro-LED 5 and the surface of the dielectric material 13 form a flat surface . On the flat surface a transparent electrode 16 is attached . The transparent electrode 16 covers the flat surface completely at present . The transparent electrode 16 is in direct contact with the micro-LED 5 and electrically contacts the micro-LED 5 . The transparent electrode 16 forms a flat surface , which can be easily covered with a micro optic element 4 .

[0105] Since the emission characteristic of the electromagnetic radiation emitted by the micro-LED is very similar to a Lambertian radiation characteristic ( see the shaded area together with the arrows ) , a part of the electromagnetic radiation of the micro-LED 5 is emitted via a side face of the micro-LED 5 . The electromagnetic radiation emitted from the side face of the micro-LED 5 impinges on the side face 14 of the cavity 12 and is redirected by the mirror layer 11 to an emission face 7 of the display .

[0106] Compared to the sub-pixel R according to the exemplary embodiment of Figures 24 and 25 , the sub-pixel R according to the exemplary embodiment of Figure 26 comprises a micro optic element 4 attached in direct contact to the transparent electrode 16 . Particularly, the micro optic element 4 is a TIR-lens 17 . The TIR-lens 17 comprises a high refractive region 30 which is laterally surrounded by a low refractive region 31 . The high refractive region 30 has a high refractive index for the electromagnetic radiation emitted by the micro-LED 5 . The low refractive region 31 has a low refractive index for the electromagnetic radiation emitted by the micro-LED 5 . At an interface 32 of the high refractive region 30 and the low refractive region 31 , electromagnetic radiation emitted by the micro-LED 5 is totally internally reflected and redirected to an emission surface 7 of the display . Further, in a central volume part of the high refractive region 30 , the TIR-lens 17 comprises a lens element 33 further collimating electromagnetic radiation of the micro-LED 5 directly running through the lens element 33 .

[0107] Compared to the sub-pixel R of the exemplary embodiment of Figure 26 , the sub-pixel R according to the exemplary embodiment of Figure 27 comprises a micro optic element 4 arranged at a distance to the micro-LED 5 . For example , the micro optic element 4 is part of a movable micro optic array 24 . Particularly, electromagnetic radiation emitted via the side faces of the micro-LED 5 is redirected by the sloped side faces 14 of the cavity 12 and directed to the micro optic element 4 . The micro optic element 4 further collimates the electromagnetic radiation . Particularly, the micro optic element 4 redirects the electromagnetic radiation perpendicular to a main extension plane of the emission surface 7 of the display .

[0108] The display according to the exemplary embodiment of Figure 28 comprises a pixel 1 having a first set of sub-pixels 2 , each provided with a micro-LED 5 emitting light of di f ferent colors . For example , the sub-pixels emit red light , green light and blue light . The first set of sub-pixels 2 emits non-collimated electromagnetic radiation, while the second set of sub-pixels 3 is provided with micro optic elements 4 , as for example described in connection with Figure 26 . According to Figure 28 , the pixel 1 is operated in a normal operation mode , wherein the micro-LEDs 5 of the first set of sub-pixels 2 are switched on . The second set of sub-pixels 3 provided with micro optic elements 4 for collimation of the electromagnetic radiation emitted by the micro-LEDs 5 is switched of f in this operation mode .

[0109] Figure 29 shows a privacy operation mode of a pixel 1 comprising the sub-pixel R of Figure 26 in a second set of sub-pixels 3 . During the privacy operation mode of Figure 29 only the micro-LEDs 5 of the second set of sub-pixels 3 are switched on, while the micro-LEDs 5 of the first set of subpixels 2 are switched of f . The light emitted by the micro- LEDs 5 of the second set of sub-pixels 3 is collimated by micro optic elements 4 , as for example already explained in connection with Figure 26 . In a first step of the method for manuf cturing a plurality of micro optic elements 4 , particularly for a display, according to the exemplary embodiment of Figures 30 to 36 , an uncured layer of a low refractive resin 19 is applied to a carrier 18 ( Figure 30 ) .

[0110] In a next step, a tool 20 having a structured surface is pressed into the uncured layer of the low refractive resin 19 such that the layer of the low refractive resin 19 is structured with the tool 20 . Particularly, the structured surface of the tool 20 is imprinted in the layer of the low refractive resin 19 ( Figure 31 ) .

[0111] After structuring the layer of low refractive resin 19 with the tool 20 , the layer of the low refractive resin 19 comprises a base structure 34 with adj acently arranged recesses 21 ( Figure 32 ) . After structuring, the layer of the low refractive resin 19 is cured, for example by radiation with electromagnetic radiation .

[0112] Then, the recesses 21 of the base structure 34 of the low refractive resin layer 19 are completely filled with layer of a high refractive resin 22 such that a planar surface is achieved ( Figure 33 ) .

[0113] The uncured layer of high refractive resin 22 is structured by imprinting with a further tool 20 ' having also a structured surface ( Figure 34 ) . After structuring, the layer of the high refractive resin 22 is cured such that a stable resin compound is achieved ( Figure 35 ) . In a further step, as shown in Figure 36 , the stable resin compound is separated such that micro optic elements 4 are generated . The micro optic elements are , for example , embodied as described in connection with Figure 29 . Particularly, material of the layer of the high refractive resin 22 forms the high refractive regions 30 , and material of the layer of the low refractive resin 19 forms the low refractive regions 31 .

[0114] This application claims priority of the German application DE 102023115634 . 9 , the disclosure content of which is incorporated herein by reference .

[0115] The invention is not limited to the description of the exemplary embodiments . Rather, the invention comprises each new feature as well as each combination of features , particularly each combination of features of the claims , even i f the feature or the combination of features itsel f is not explicitly given in the claims or the exemplary embodiments .

[0116] References

[0117] 1 pixel

[0118] 2 first set of sub-pixels

[0119] 3 second set of sub-pixels

[0120] 4 micro optic element

[0121] 5 micro-LED

[0122] 6 beam cone

[0123] 7 emission surface

[0124] 8 light spot

[0125] 9 conductor track

[0126] 10 substrate

[0127] 11 mirror layer

[0128] 12 cavity

[0129] 13 dielectric material

[0130] 14 side face of the cavity

[0131] 15 bottom face of the cavity

[0132] 16 transparent electrode

[0133] 17 TIR-lens

[0134] 18 carrier

[0135] 19 layer of low refractive resin

[0136] 20 , 20 ' tool

[0137] 21 recess

[0138] 22 layer of high refractive index

[0139] 23 plate

[0140] 24 micro optic array

[0141] 25 actuator

[0142] 26 3D-sensor

[0143] 27 camera

[0144] 28 image

[0145] 29 opening of the cavity

[0146] 30 high refractive region

[0147] 31 low refractive region

[0148] 32 interface

[0149] 33 lens element

[0150] 34 base structure R red emitting sup-pixel

[0151] G green emitting sup-pixel

[0152] B blue emitting sup-pixel al , a2 aperture angle

[0153] P angle dl first diameter d2 second diameter

[0154] D diagonal of the pixel

Claims

Claims1. Display comprising:- a plurality of pixels (1) , wherein- each pixel (1) has a first set of at least two sub-pixels (2) and a second set of at least two sub-pixels (3) ,- each sub-pixel (R, G, B) comprises a micro-LED (5) emitting electromagnetic radiation during operation, and- micro optic elements (4) are arranged above the micro-LEDs (5) of the second set of sub-pixels (3) , the micro optic elements (4) collimating beam cones (6) of the electromagnetic radiation of the micro-LEDs (5) of the second set of sub-pixels (3) .

2. Display according to the previous claim, wherein beam cones (6) of the electromagnetic radiation of the subpixels of the first set of sub-pixels (2) are not collimated.

3. Display according to any of the previous claims, wherein the beam cones (6) of the electromagnetic radiation of the micro-LEDs (5) of the first set of sub-pixels (2) have an aperture angle (al) larger than an aperture angle (a2) of the beam cones (6) of the electromagnetic radiation of the micro-LEDs (5) of the second set of sub-pixels (3) at an emission surface (7) of the display.

4. Display according to any of the previous claims, wherein the micro optic elements (4) are attached to the micro-LEDs (5) of the second set of sub-pixels (3) .

5. Display according to any of claims 1 to 3, whereinthe micro optic elements (4) are part of a movable micro optic array (24) arranged over the micro-LEDs (5) of the second set of sub-pixels (3) .

6. Display according to any of the previous claims, wherein at least the micro-LEDs (5) of the second set of sub-pixels (3) are arranged within cavities (12) of a substrate (10) , the cavities (12) having sloped side faces (14) .

7. Display according to the previous claim, wherein the side faces (14) of the cavities (12) are covered with mirror layers (11) .

8. Display according to any of claims 6 to 7, wherein the cavities (12) are filled with a dielectric material (13) .

9. Display according to any of claims 6 to 8, wherein the cavities (12) are covered with a transparent electrode (16) being in direct contact with the micro-LEDs (5) arranged within the cavities (12) .

10. Display according to any of the previous claims, wherein the micro optic elements (4) comprise TIR-lenses (17) .

11. Display according to any of the previous claims, further comprising a 3D-sensor (26) and / or a camera (27) configured to detect an object in the environment of the display.

12. Display according to any of the previous claims, further comprising an actuator (25) configured to move the micro optic elements (4) .

13. Display according to any of the previous claims, whereinthe sub-pixels (R, G, B) of a pixel (1) are arranged in a diagonal (D) of the pixel (1) .

14. Method for operating a display having a plurality of pixels ( 1 ) , wherein- each pixel (1) has a first set of at least two sub-pixels (2) and a second set of at least two sub-pixels (3) ,- each sub-pixel (R, G, B) comprises a micro-LED (5) emitting electromagnetic radiation during operation,- micro optic elements (4) are arranged above the micro-LEDs (5) of the second set of sub-pixels (3) , the micro optic elements (4) collimating beam cones (6) of the electromagnetic radiation of the micro-LEDs (5) , the method comprising the step:- switching on the micro-LEDs (5) of the first set of the at least two sub-pixels (2) and / or the micro-LEDs (5) of the second set of the at least two sub-pixels (3) .

15. Method according to the previous claim, wherein beam cones (6) of the micro-LEDs (5) of the second set of sub-pixels (3) are tilted with respect to a normal of the emission surface (7) of the display by shifting the micro optic elements (4) , when the micro-LEDs (5) of the second set of sub-pixels (3) are switched on.

16. Method according to any of claims 14 to 15, further comprising the steps:- detecting a location of an object in the environment of the display, and- shifting the micro optic elements (4) dependent on the detected location of the object.

17. Method according to any of claims 14 to 16, wherein the micro optic elements (4) are shifted such that a resolution of the display is enhanced by a factor four compared to a normal mode.

18. Method for manufacturing a plurality of micro optic elements (4) , particularly for a display, comprising the steps :- providing a carrier (18) , - applying a layer of a low refractive resin (19) on the carrier (18) ,- structuring the layer of the low refractive resin (19) ,- applying a layer of a high refractive resin (22) on the structured layer of the low refractive resin (19) , and - structuring the layer of the high refractive resin (22) .

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