Method for force touch sensing, device for force touch sensing and input device

Abstract

A method for force touch sensing is provided, the method comprising touching a sensing surface of a device with an object, wherein the object comprises a structure on an outer surface, in first regions of the sensing surface, the structure is in direct contact with the sensing surface, and in second regions of the sensing surface, the structure is distant to the sensing surface. The method further comprises determining the ratio of the first regions of the sensing surface to the second regions of the sensing surface, wherein the structure is configured to be deformed depending on a force of the object on the sensing surface. Furthermore, a device for force touch sensing and an input device for generating touch input are provided.

Description

[0001] Description

[0002] METHOD FOR FORCE TOUCH SENSING, DEVICE FOR FORCE TOUCH SENSING AND INPUT DEVICE

[0003] A method for force touch sensing, a device for force touch sensing and an input device are provided.

[0004] It is an object to provide an efficient method for force touch sensing. A further object is to provide an efficient device for force touch sensing. Another object is to specify an input device to efficiently provide input to a device for force touch sensing.

[0005] These objects are solved by a method for force touch sensing, a device for force touch sensing and an input device according to the independent claims. Further embodiments of the method for force touch sensing, the device for force touch sensing and the input device are the subject matter of the further claims.

[0006] According to at least one embodiment of the method for force touch sensing, the method comprises touching a sensing surface of a device with an object. For example, the device comprises a display or a smart surface.

[0007] For example, the display or the device comprises the functioning and / or structuring of a display or display device described in the applications DE 10 2023 125 788.9, DE 10 2023 125 786.2 or DE 10 2023 125 785.4, the disclosure of which is incorporated herein by reference. The sensing surface can be an outer surface of the device, e.g. a surface of the device which is accessible by the object. The sensing surface can be arranged as a single sensing surface over a display or smart surface of a device, for example. This can also mean that the sensing surface is the display or is comprised by the display. Alternatively, the sensing surface can consist of or comprise a plurality of sensing surfaces arranged spaced apart from each other.

[0008] According to at least one embodiment, the object comprises a structure on an outer surface. In particular, the object comprises at least partially a structure on the outer surface of the object. That the outer surface of the object comprises the structure may mean that the outer surface of the object is at least partially non-planar. For instance, the structure comprises ridges and / or valleys.

[0009] For example, the object is or comprises a finger, in particular a human finger, or an input device, for instance a glove or a pen. In case the touch is conducted with a human finger, the structure can be a fingerprint profile or a fingerprint pattern. However, the object can be any component comprising a structure which is deformable under force and being suitable for touching the sensing surface.

[0010] According to at least one embodiment of the method for force touch sensing, in first regions of the sensing surface the structure, in particular the structure of the object, is in direct contact with the sensing surface. For example, ridges of the structure are at least partially in direct contact with the sensing surface. This can mean that only a tip portion of the ridge is in direct contact with the sensing surface. Under force, the ridge of the structure can be flattened, such that the portion of the structure or the ridge in direct contact with the sensing surface of the device is increased . Regions between two adj acent ridges may be referred to as valleys . For instance , the valleys of the structure are not in direct contact with the sensing surface .

[0011] According to at least one embodiment of the method for force touch sensing, in second regions of the sensing surface , the structure is distant to the sensing surface . It is possible that the second regions of the sensing surface overlap with the valleys of the structure of the obj ect . In other words , the structure may be distant to the sensing surface at least in the regions of the valleys of the structure .

[0012] According to at least one embodiment , the method for force touch sensing comprises determining the ratio of the first regions of the sensing surface to the second regions of the sensing surface .

[0013] According to at least one embodiment of the method for force touch sensing, the structure is configured to be deformed depending on a force of the obj ect on the sensing surface . For example , the force is applied along a direction perpendicular to the direction along which the ridges and valleys of the structure are alternatingly arranged . This can mean that the force is applied along a direction perpendicular or at least approximately perpendicular to a main extension plane of the sensing surface . In particular, the force can be applied by the obj ect onto the sensing surface . Under such a force , the ridges of the structure are flattened, for example . This increases the ratio of the first regions of the sensing surface to the second regions of the sensing surface. In other words, a percentage of first regions of the sensing surface can be increased.

[0014] According to at least one embodiment of the method for force touch sensing, the method comprises touching a sensing surface of a device with an object, wherein the object comprises a structure on an outer surface, in first regions of the sensing surface, the structure is in direct contact with the sensing surface, and in second regions of the sensing surface, the structure is distant to the sensing surface. The method further comprises determining the ratio of the first regions of the sensing surface to the second regions of the sensing surface, wherein the structure is configured to be deformed depending on a force of the object on the sensing surface.

[0015] The force touch sensing, e.g. conducted with the method for force touch sensing described herein, can be used as a second input type or as a redundancy for touch sensing. For example, in consumer applications, it is desired to have multiple functions in a smart or touch display, e.g. "touch", "long touch" or "force touch". For example, "force touch" using force touch sensing can be advantageous compared to "long touch" as less time is required. For automotive and medical applications, for example, the force touch sensing may be used as a redundancy to confirm that a touch was actually intended. For instance, the touch is only intended if it is within a predetermined force interval. In particular, the touch might be intended if the force is larger than a threshold value.

[0016] In case the object is a finger, in particular a human finger, fingerprint detection is used to detect a force touch. For instance , the ridges in the fingerprint profile are compressed when pressing harder onto a surface , e . g . a display or smart surface , or in particular onto the sensing surface of the device . This can lead to a change in the duty cycle of the fingerprint pattern on the sensing surface . Thereby, "duty cycle" can be understood as the percentage of first regions of the sensing surface . For example , a high pressure or force during force touch alters the ratio of ridges and valleys in the structure and can therefore be used to distinguish between a force touch and normal touch . When determining the duty cycle , the percentage of first regions or the ratio of first regions to second regions of the sensing surface , only areas of the sensing surface touched by an obj ect , e . g . areas of interest , are considered . For example , masking is used to analyse only the areas of interest . The ratio can be determined using an algorithm, for example .

[0017] In general , with the method for force touch sensing described herein an imprint of the structure of the obj ect on the sensing surface can be determined to detect a force touch .

[0018] Comparative force touch sensors comprise a movable or bendable cover glass . The stroke of the glass while moving or bending the cover glass is then detected as force touch .

[0019] Advantageously, the method for force touch sensing described herein does not rely on a force touch sensor comprising movable or bendable parts , for example a movable or bendable cover glass .

[0020] Another advantage of the method for force touch sensing described herein is that it allows for multi-point detection . For example, multiple objects touching the sensing surface or parts of the sensing surface can be resolved, e.g. one object or finger force touch and a further object or finger normal touch .

[0021] For instance, the method for force touch sensing can be a method to determine force touch interaction. For this, for example a fingerprint pattern on a display with a bigger area can be used. Thus, for example, with the method for force touch sensing it is possible to obtain a spatial coordinate of the position where the force was applied.

[0022] According to at least one embodiment of the method for force touch sensing, the touch of the object is classified as force touch in case the determined ratio is above a threshold value. The touch of the object can be classified as normal touch in case the determined ratio below the threshold value and above a further threshold value. In other words, the touch is classified as normal touch in case the determined ratio is between the threshold value and the further threshold value, for example. If there is only one threshold value, e.g. the method for force touch sensing is conducted to distinguish between two possible outcomes, the touch can be classified as normal touch in case the determined ratio is below the threshold value. For example, the touch of the object can be classified as soft touch in case the determined ratio is below the further threshold value. Here, in particular, the determined ratio can be the ratio of the first regions of the sensing surface to the second regions of the sensing surface.

[0023] For example, the touch is classified using a discriminator or comparator. In particular, the touch can be classified by comparing the determined ratio of the first regions of the sensing surface to the second regions of the sensing surface with the threshold value and / or the further threshold value. It is further possible, that the device is configured to provide haptic feedback, e.g. a vibration, depending on the classification of the touch. For example, in case the touch is classified as force touch, the device may provide haptic feedback. For example, the threshold value is larger than the further threshold value. For instance, the threshold value and / or the further threshold value are given by a percentage.

[0024] It is then possible to efficiently classify or identify a touch as normal touch, as soft touch or as force touch. This can allow for more functionality of smart or touch surfaces or function as a redundancy to check if the touch with the object or input device was intended by a user.

[0025] According to at least one embodiment of the method for force touch sensing, the force of the object on the sensing surface is proportional to a parameter to be adjusted. In particular, the force touch sensing can be used to control or adjust a parameter of the device for force touch sensing or of an external device. In this case, it is possible that the obtainable result of the touch of the object comprises more than two or three possible values, e.g. normal touch and force touch or normal touch, force touch and soft touch, for example a plurality of possible values. It is possible, that the force detection is linear. In other words, the method for force touch sensing or the device can be used to detect a plurality of forces. In this case, the force touch sensing can be used as a linear input device. Possible applications in this case are volume tuning or display brightness control, for example. This can mean that the force of the touch of the object detected or sensed is proportional to a parameter to be adjusted, e.g. the volume or the brightness.

[0026] According to at least one embodiment, the structure of the object comprises ridges and / or valleys. At the ridges, the structure is in direct contact with the sensing surface. For instance, the ridges are flattened under the force of the object on the sensing surface.

[0027] According to at least one embodiment, the object comprises a finger. Then, for instance, the structure of the object is a fingerprint pattern or fingerprint profile. Thus, the device comprising the sensing surface can easily be touched by a user, without the need for further components.

[0028] According to at least one embodiment of the method, the device comprises a light source, configured to emit electromagnetic radiation onto a side of the sensing surface facing away from the object. The device can further comprise a detector, configured to detect the electromagnetic radiation reflected at the sensing surface. For instance, the light source can be configured to emit electromagnetic radiation in the visible and / or near-infrared (NIR) spectrum.

[0029] The detector can be configured to detect the electromagnetic radiation emitted by the light source. For example, the detector is or comprises a LED, e.g. a pLED. In case the LED or pLED is or is comprised by the detector, the LED or pLED can be configured to detect electromagnetic radiation. This can mean that the LED or pLED is reverse biased. Alternatively, the LED or pLED can be driven in zero bias . Then, the photocurrent generated in the device or in the pLED under external radiation is read out .

[0030] It is also possible , that the detector is or comprises a photodiode , in particular a silicon photo diode ( Si PD) , for example an embedded Si PD . The detector can be or can comprise a micro photodiode (pPD) . For example , the pPD can be a discrete silicon photo diode .

[0031] According to at least one embodiment , the light source comprises at least one pLED . Additionally or alternatively, the detector comprises at least one pLED .

[0032] As a broad definition, a pLED or micro-LED could be seen as any light emitting diode ( LED) - generally not a laser - with a particularly small si ze .

[0033] As a rule - and this is a very important criterion in addition to si ze - a growth substrate is removed from microLEDs , so that typical heights of such micro-LEDs are in the range of 0 . 5 pm to 10 pm, for example .

[0034] In principle , a micro-LED does not necessarily have to have a rectangular radiation emission surface . Generally, for example , a pLED could have a radiation emission surface in which, in plan view of the layers of the layer stack, any lateral extent of the radiation emission surface is less than or equal to 100 pm or less than or equal to 70 pm . For example , in the case of rectangular micro-LEDs , an edge length - especially in plan view of the layers of the layer stack - smaller than or equal to 70 pm or smaller than or equal to 50 pm is often cited as a criterion . For example , an edge length of the micro-LED can be less than or equal to 10 gm.

[0035] Mostly, such micro-LEDs are provided on wafers with - for the gLED non-destructively - detachable holding structures. At present, micro-LEDs are mainly used in displays. The micro-LEDs form pixels or subpixels and emit light of a defined wavelength. Small pixel size and a high density with close distances make micro-LEDs suitable, among others, for small monolithic displays for AR applications, especially data glasses. In addition, other applications are being developed, in particular regarding the use in data communication or pixelated lighting applications.

[0036] Different ways of spelling micro-LED, e.g. gLED, g-LED, uLED, u-LED or micro light emitting diode can be found in the relevant literature.

[0037] According to at least one embodiment, the light source comprises a plurality of red, green and / or blue LEDs. The green LEDs can be configured to illuminate the sensing surface. This can mean that during operation of the device, e.g. during conducting the method for force touch sensing, the green LEDs illuminate the sensing surface. The red LEDs can be configured to detect the reflected electromagnetic radiation. For this, the red LEDs can be reversed biased. For instance, the green LEDS illuminate the sensing surface and the red LEDs are reversed biased and detect the reflected electromagnetic radiation during force touch sensing. It is also possible, that the red LEDs are driven at zero bias. In particular, the photocurrent of the red LED is read out. This can mean that force touch sensing can be efficiently implemented in displays. For instance, at least some of the display LEDs or pLEDs can be adapted for force touch sensing. In other words, at least some of the display LEDs or pLEDs can be used for touch and force touch sensing. This can mean that the display LEDs or pLEDs comprise dual use, e.g. as display LED or pLED and as sensor for force touch sensing.

[0038] According to at least one embodiment, the light source emits near-infrared radiation during force touch sensing. For example, the light source is configured for emitting nearinfrared radiation. The light source may comprise a nearinfrared LED or pLED, for example. In this case, the detector preferably is or comprises a near-infrared sensitive detector. For instance, the detector is configured to detect near-infrared radiation during operation or during conducting the method for force touch sensing. In particular, the detector can comprise a Si photodiode, for example a micro Si photodiode, or a plurality of Si (micro) photodiodes.

[0039] For example, the near-infrared light source / s and / or the near-infrared photodiode / s are implemented in the display plane, e.g. adjacent to the display LEDs or display pLEDs. Alternatively, the device for force touch sensing can be applied on a smart surface, for example on a touch-sensitive surface .

[0040] Near-infrared radiation is invisible for the human eye. Thus, an advantage of this embodiment is that a user is not distracted by visible electromagnetic radiation during force touch sensing.

[0041] According to at least one embodiment, the device is or comprises a display fingerprint sensor. For example, the device comprises a full display fingerprint sensor. This means that the complete or almost the complete display of the device is configured for fingerprint sensing, in general for sensing the structure of the object or for force touch sensing .

[0042] However, force touch sensing with the method described herein does not necessarily require a high resolution fingerprint sensor spread over the entire display area. For instance, force touch sensing also functions when using a plurality of sensing surfaces, e.g. clusters. Each cluster may comprise a plurality of photodiodes. For example, the photodiodes in a cluster are discretely arranged on a flexible substrate. The photodiodes can be micro photodiodes or reverse biased pLEDs, for example. However, any type of detector configured to detect electromagnetic radiation can be suitable.

[0043] The clusters can be arranged in a grid-like shape. For instance, the clusters are spaced similar or equal to usual capacitive touch sensor grids. For example, the device is only touch-sensitive within the clusters.

[0044] The structure, e.g. the fingerprint profile does not need to be detected across the entire touch sensitive surface, but can be efficiently detected using the clusters. As less data is collected and analysed using clusters, the force touch sensing can be faster compared to a full display fingerprint sensor, for example.

[0045] Additionally, these clusters can be mounted on a flexible substrate. Therefore, they can easily be applied on arbitrarily shaped surfaces. According to at least one embodiment , the device comprises multiple sensing surfaces . For instance , during the method for force touch sensing, the sensing surfaces are touched by the obj ect . For example , for determining the ratio of the first regions to the second regions , an overall ratio of the first regions to the second regions can be averaged over ratios of the first regions to the second regions of the touched sensing surfaces . Each sensing surface can be referred to as a cluster .

[0046] For example , a resolution of the detector in each sensing surface or in each cluster is at least 200 ppi (pixel per inch) , for instance at least 250 ppi or at least 400 ppi . In particular, the resolution of the detector in each sensing surface can be around 500 ppi . The resolution of the detector can be the density of photodiodes within the cluster .

[0047] A distance between adj acent photodiodes within a cluster can be between and including 5 pm and 150 pm, for instance between and including 10 pm and 100 pm or between 15 pm and 70 pm, inclusive . For example , the distance between adj acent photodiodes is at most 100 pm or, in particular, around 50 pm .

[0048] A distance between adj acent clusters or sensing surfaces can be between and including 2 mm and 15 mm, for example between and including 4 mm and 10 mm .

[0049] For example , such a cluster or sensing surface is configured to detect at least one ridge and one valley of the structure , e . g . of the fingerprint profile . For example , a ridge distance in a fingerprint pattern or fingerprint profile is at least approximately within a range from 400 pm to 600 pm . Detecting one ridge and one valley of the structure may be suf ficient to ef ficiently sense a force touch .

[0050] According to at least one embodiment , the sensing surfaces are arranged at lattice points of a regular lattice . The sensing surfaces can be arranged spaced apart from each other . For example , the sensing surfaces are arranged at lattice points of a rectangular, triangular or hexagonal lattice .

[0051] Furthermore , a device for force touch sensing is provided . The device for force touch sensing can be the device of the method for force touch sensing described herein . This means for instance that all features disclosed for the method for force touch sensing are also disclosed for the device for force touch sensing and vice-versa .

[0052] According to at least one embodiment of the device for force touch sensing, the device comprises a plurality of sensing surfaces , wherein each sensing surface is configured to detect a structure of an obj ect on the respective sensing surface . For example , the plurality of sensing surfaces form the sensing surface of the device . Each of the plurality of sensing surfaces can be referred to as a cluster .

[0053] An idea is to provide a device which can be operated ef ficiently for force touch sensing . Additionally, the sensing surfaces can be applied to arbitrarily shaped surfaces .

[0054] For instance , having a breakdown of a big fingerprint scanner with high resolution into a grid of clusters can lead to spatial resolution . In other words , the device can be an all optical touch screen with force touch function. The clusters can have high enough resolution for force touch recognition, e.g. by fingerprint compression, and can be sparsed out over a screen with a pitch of around 6 mm, for example. The pitch can correspond to the touch screen resolution.

[0055] With the device, for instance, a spatial coordinate of the position, where a force was applied, can be obtained. It is also possible, that the device is configured to or suitable to resolve a touch of multiple fingers, for instance with one finger applying a force at a position and another finger touching without force at a different position.

[0056] According to at least one embodiment of the device, each sensing surface comprises or is assigned to a light source configured to emit electromagnetic radiation and a plurality of detector units configured to detect electromagnetic radiation .

[0057] For example, each cluster defining one sensing surface comprises exactly one light source. For example, the cluster comprises one central illumination unit. In other words, a central pixel of the cluster can comprise the light source. Then, the surrounding pixels comprise detector units, e.g. photodiodes. In this case, the light source can be arranged in-plane with the detector units.

[0058] Alternatively, the light source can be arranged on the side of the detector units facing away from a cover, e.g. a sensing surface. This can mean that the light source overlaps with a plurality of detector units or photodiodes. It is also possible , that one cluster comprises multiple light sources . For example , one cluster comprises four light sources which are evenly distributed within the cluster .

[0059] Alternatively, it is also possible , that multiple cluster of the plurality of clusters or all clusters share a common light source . In this case , the light source can be referred to as global light source . For example , the electromagnetic radiation is guided to the clusters via a light guide or light guides . The light guide / s can be arranged in or on the substrate , in particular in or on the flexible substrate .

[0060] According to at least one embodiment of the device , the sensing surfaces are arranged on a flexible substrate . In other words , the flexible substrate can be deformed to adj ust to an arbitrarily shaped surface .

[0061] According to at least one embodiment of the device , a spacing between adj acent sensing surfaces is between 4 mm and 10 mm .

[0062] Furthermore , an input device for generating touch input is speci fied . The input device can generate touch input in the method for force touch sensing described herein . This means for instance that all features disclosed for the method for force touch sensing are also disclosed for the input device and vice-versa .

[0063] According to at least one embodiment of the input device for generating touch input , the input device comprises a part with a structured outer surface . The structure can comprise ridges and valleys . For example , the structure is configured to be deformed under force . That the input device comprises a part with a structured outer surface can mean that an outer surface of the input device is at least partially structured . In particular, the structure comprises or consists of ridges and / or valleys . A ridge is understood as a part of the outer surface , e . g . the structured outer surface , which at least locally protrudes remaining regions of the outer surface . For example , a remaining region, in particular a region which does not comprise a ridge , can be referred to as valley .

[0064] For instance , the input device is or comprises a glove or at least a part of a glove . However, the input device can be of any shape or be any component suitable to provide or generate a touch input .

[0065] The ridges of the structure may comprise a main extension direction . In other words , an extension of the ridge along the main extension direction is larger than an extension of the ridge along a further direction which extends perpendicular or at least approximately perpendicular to the main extension direction of the ridge .

[0066] For example , the structure of the input device comprises a stripe pattern . The stripe pattern can be a regular stripe pattern . This means , that the structure comprises equally spaced ridges . Thereby, the ridges run in parallel to each other . In other words , the main extension direction of one ridge extends in parallel to the main extension direction of another one of the ridges . That the stripe pattern is a regular stripe pattern can also mean that a shape of the ridges , in particular a cross-section of the ridges is the same for the ridges of the structure . Alternatively, it is also possible, that at least one ridge comprises a different shape than an adjacent ridge. Further, it is possible that a distance between adjacent ridges is equal for the complete structure of the input device. However, it is also possible, that the ridges of the structure of the input device are not evenly spaced and / or distributed .

[0067] For instance, the structure can resemble a fingerprint pattern or fingerprint profile.

[0068] The distance or a spacing between adjacent ridges of the structure of the input device can be between 400 pm and 600 pm. For example, this distance range corresponds to the spacing between ridges in a fingerprint pattern.

[0069] According to at least one embodiment of the input device, the structure of the part comprises a refractive index, which is at least approximately equal to the refractive index of a human skin. For example, the refractive index of the human skin is between and including 1.35 and 1.55. The refractive index of the human skin can depend on the water content, e.g. dry or wet finger. For example, the structure is formed of or comprises silicone, for instance polydimethylsiloxane. Silicone may comprise a refractive index of approximately 1.45. Thus, the same method for force touch sensing can be efficiently used for sensing a force generated by a human finger or by the input device for generating touch input.

[0070] According to at least one embodiment of the input device, the structure comprises silicone. For example, silicone can mimic the optical properties of human skin, e.g a human finger. According to at least one embodiment , a cross-section of the structure comprises a wave-shape , a triangular shape or a sawtooth-shape . Alternatively, the cross-section of the structure can comprise the shape of a triangle with removed tip . In particular, the cross-section of the structure is non-rectangular . Such a structure can be ef ficiently deformed, e . g . compressed and / or flattened, under a force .

[0071] Further advantages and advantageous designs and further developments of the method for force touch sensing, the device for force touch sensing and the input device for generating touch input will become apparent from the following exemplary embodiments , which are described below in association with the figures .

[0072] Figures 1 and 2 show schematic views of a method for force touch sensing or a device for force touch sensing according to exemplary embodiments .

[0073] Figure 3A, 3B and 3C show schematic views of a method for force touch sensing according to an exemplary embodiment .

[0074] Figure 4 show an exemplary result obtained with a method for force touch sensing according to an exemplary embodiment .

[0075] Figure 5 shows a device for force touch sensing according to an exemplary embodiment .

[0076] Figures 6A, 6B and 6C shows a method for force touch sensing according to an exemplary embodiment using the device for force touch sensing shown in Figure 5 . Figures 7A, 7B, 7C, 7D and 7E show an exemplary result of a method for force touch sensing according to an exemplary embodiment .

[0077] Figures 8A, 8B and 8C show a schematic view of a device for force touch sensing according to an exemplary embodiment .

[0078] Figures 9A, 9B, 10A and 10B show schematic views of devices for force touch sensing according to further exemplary embodiments .

[0079] Figure 11 shows an input device for generating touch input according to an exemplary embodiment .

[0080] Figures 12A, 12B and 12C show schematic views of structures of an input device according to exemplary embodiments .

[0081] Figure 13A, 13B and 13C show schematic views of a method for force touch sensing using an input device according to an exemplary embodiment .

[0082] Figure 14 shows a schematic view of a method for force touch sensing according to a comparative example .

[0083] Identical , similar, or equivalent elements are marked with the same reference signs in the figures . The figures and the proportions of the elements represented in the figures among each other are not to be considered as true to scale . Rather, individual elements may be oversi zed for better representability and / or comprehensibility . Identical or ef fectively identical components and parts might be described only with respect to the figures where they occur first . Their description is not necessarily repeated in successive figures .

[0084] Figure 1 shows a schematic view of a method for force touch sensing or of a device 1 for force touch sensing according to an exemplary embodiment . The device 1 can be or can comprise a fingerprint sensor, for example a display fingerprint sensor or full display fingerprint sensor . The device 1 comprises a light source 14 and a detector 15 . The light source 14 can be or can comprise a pLED . For example , shown here , the device 1 comprises a display with red, green and blue emitting display LEDs , in particular pLEDs . Then, one or more of the green LEDs can form the light source 14 for force touch sensing . In other words , during force touch sensing, at least one of the green LEDs emits electromagnetic radiation 5 . The electromagnetic radiation 5 is at least partially or only partially reflected at a cover 10 , a coating 20 or a sensing surface 11 of the device 1 to form reflected electromagnetic radiation 50 .

[0085] During force touch sensing, the sensing surface 11 of the device 1 may be touched by an obj ect 2 . The obj ect 2 comprises a structure 22 on an outer surface 21 . In first regions 12 of the sensing surface 11 , the structure 22 is in direct contact with the sensing surface 11 . For example , the structure 22 comprises at least one ridge 23 , which is in direct contact with the sensing surface 11 . In second regions 13 of the sensing surface 11 , the structure 22 is distant to the sensing surface 11 . For example , the structure 22 comprises at least one valley 24 , which is not in direct contact with the sensing surface 11 of the device 1 . A portion of the emitted electromagnetic radiation 5 may be scattered into a medium directly adjacent to the sensing surface 11. This portion of the emitted electromagnetic radiation 5 can be referred to as scattered electromagnetic radiation 51. For instance, the medium directly adjacent to the sensing surface 11 is the object 2, in particular the ridges 23 of the structure 22 of the object 2. Thus, in first regions 12 of the sensing surface 11 less electromagnetic radiation is reflected towards the detector 15, e.g. the display pLEDs than in second regions 13 of the sensing surface 11.

[0086] For example, at least some of the red pLEDs are configured to detect the reflected electromagnetic radiation 50. This can mean that during force touch sensing, at least some of the red pLEDs are reverse biased and detect the reflected electromagnetic radiation 50.

[0087] Shown here, the object 2 is or comprises a finger 4, e.g. a human finger 4. The structure 22 of the object can be a fingerprint pattern 41. Alternatively, the structure 22 may be comprised by an input device 3, for example a glove or a pen .

[0088] The cover 10 can be a cover glass, for example. For example, the coating 20 is applied to the side of the cover facing away from the light source 14 and the detector 15. The coating 20 can be configured to enhance the reflectivity in the second regions 13, for example. The cover 10 and / or the coating 20 may form or comprise the sensing surface 11.

[0089] The method for force touch sensing can comprise determining the ratio of the first regions 12 of the sensing surface 11 to the second regions 13 of the sensing surface 11 , for example using an algorithm . As the structure 22 is configured to be deformed depending on a force of the obj ect 2 on the sensing surface 11 , the applied force correlates with the ratio of the first regions 12 to the second regions 13 .

[0090] Figure 2 shows a schematic view of a method for force touch sensing or a device for force touch sensing according to an exemplary embodiment . The device for force touch sensing according to the exemplary embodiment shown in Figure 2 di f fers from the exemplary embodiment shown in Figure 1 in that the light source 14 emits near-infrared radiation during force touch sensing . In this case , the detector 15 is configured to detect near-infrared radiation (NIR) . For example , the device 1 is a device 1 according to the embodiment shown in Figure 1 , wherein the device 1 additionally comprises the near-infrared light source 14 and / or the near-infrared detector 15 . In other words , the device 1 may comprise the near-infrared light source 14 and the near-infrared detector 15 for force touch sensing in addition to the display pLEDs . The light source 14 can comprise a NIR pLED . The detector 15 can be or can comprise a NIR sensitive detector, e . g . a S I photodiode .

[0091] Figure 3A, 3B and 3C show schematic views of a method for force touch sensing according to an exemplary embodiment . In Figure 3A, the obj ect 2 with the structure 22 is distant to the sensing surface 11 of the device 1 . This means that no touch is applied to the device 1 . In this case , the structure 22 is not detected . Thus , the image 100 comprises no information on the structure 22 . For example , as no first regions 12 of the sensing surface 11 are present , no ratio can be determined to determine a force . Figure 3B shows an example in which a low force touch, also referred to as soft touch or normal touch is applied to the device 1, in particular to the sensing surface 11 of the device 1. The structure 22 is partially in direct contact with the sensing surface 11. For example, the areas of the first regions 12 and the second regions 13 in the obtained image 100 are at least approximately equal. In other words, a duty cycle, i.e. the percentage of first regions 12, is approximately 50%.

[0092] In Figure 3C a force touch is applied. This can mean that the force of the object 2 or of the structure 22 on the sensing surface 11 is increased compared to the exemplary embodiment shown in Figure 3B. This causes a deformation of the structure 22. In particular, the ridges 23 of the structure 22 are flattened. This can increase the areas of the first regions 12 of the sensing surface 11, while the second regions 13 are decreased. Therefore, the ratio of the first regions 12 to the second regions 13 is enhanced. In other words, the duty cycle indicated in the obtained image 100 is larger than 50%.

[0093] Figure 4 show an exemplary result obtained with a method for force touch sensing according to an exemplary embodiment. On the x-axis of the graph the time is plotted in artificial units. On the y-axis, the force or pressure is plotted in artificial units. During a first time interval II, the pressure or force is low, such that the touch can be classified as a soft touch. For example, the pressure or force is below a threshold value and / or below a further threshold value. During a second time interval 12 , the pressure or force is increased . The touch can then be classi fied as a force touch . The fingerprint pattern 41 , 100 imaged during the first time interval I I shows a duty cycle of approximately 50% . In contrast , the fingerprint pattern 41 , 100 imaged during the second time interval 12 shows a duty cycle of larger than 50% .

[0094] Figure 5 shows a schematic top view of a device 1 for force touch sensing according to an exemplary embodiment . The device 1 comprises multiple or a plurality of sensing surfaces 11 . The multiple sensing surfaces 11 can form the sensing surface 11 . During force touch sensing, one or more of the sensing surfaces 11 are touched by the obj ect 2 . The sensing surfaces 11 can form a touch grid 17 . The sensing surfaces 11 are arranged at lattice points , for example at lattice points of a regular, for instance triangular, rectangular or hexagonal , lattice .

[0095] Each sensing surface 11 can be configured to detect a structure 22 or a portion of the structure 22 of the obj ect 2 , not shown, on the respective sensing surface 11 . For example , each sensing surface 11 comprises a light source 14 and a detector 15 . For example , the detector 15 comprises a plurality of detector units 16 . A resolution of the detectors 15 of each sensing surface 11 can be at least 200 ppi .

[0096] For example , a spacing between adj acent sensing surfaces 11 is between and including 4 mm and 10 mm . A ratio of the first regions 12 to the second regions 13 proportional to the applied force or pressure can be determined from only one of the sensing surfaces 11 . Alternatively, an overall ratio of the first regions 12 to the second regions 13 can be averaged over the ratios of the first regions 12 to the second regions 13 of the touched sensing surfaces 11 .

[0097] Figures 6A, 6B and 6C shows a method for force touch sensing according to an exemplary embodiment using the device for force touch sensing shown in Figure 5 . Figure 6A shows a finger 4 applying a force on the sensing surfaces 11 . Figure 6B shows an example in which a low force is applied, wherein in the example of Figure 6C a high force is applied .

[0098] Figures 7A, 7B, 70, 7D and 7E show an exemplary result of a method for force touch sensing according to an exemplary embodiment . Figure 7A shows a fingerprint pattern 41 while conducting a soft touch . The ridges 23 of the fingerprint pattern 41 shown in Figure 7B are flattened during a force touch, increasing the black areas in comparison to the fingerprint pattern 41 shown in Figure 7A. Figure 70 shows a fingerprint pattern 41 under low force .

[0099] On the x-axis of the graph shown in Figure 7E , the time is plotted in arti ficial units . On the y-axis , the pressure or force is plotted in arti ficial units . For example , the fingerprint pattern 41 shown in Figure 7A was obtained at time x = 1 , the fingerprint pattern 41 of Figure 7B was obtained at time x = 5 and the fingerprint pattern 41 of Figure 70 was obtained at time x = 9 . The four lines 01 , 02 , 03 and 04 correspond to the forces , pressures or ratios detected at the respective clusters 01 , 02 , 03 and 04 indicated in Figure 7D .

[0100] Figures 8A, 8B and 80 show schematic views of a device for force touch sensing according to an exemplary embodiment . Shown here , Figure 8A, the multiple sensing surfaces 11 or clusters 18 can be arranged on a flexible substrate 19 .

[0101] According to the exemplary embodiment shown in Figure 8B, each cluster 18 comprises exactly one light source 14 and a plurality of detector units 16 forming the detector 15 . For example , the light source 14 is arranged at least approximately at the center of the cluster 18 .

[0102] Figure 8C shows a schematic cross-sectional view of the cluster 18 shown in Figure 8B .

[0103] Figures 9A and 9B show schematic views of a device 1 for force touch sensing according to a further exemplary embodiment . The device 1 di f fers from the exemplary embodiment shown in Figures 8B and 8C in that the cluster 18 comprises four light sources 14 . The light sources 14 can be evenly distributed in the cluster 18 .

[0104] The exemplary embodiment of the cluster 18 shown in Figures 10A and 10B di f fers from the cluster 18 shown in Figures 8A and 8B in that the light source 14 is arranged on the side of the detector units 16 facing away from the cover 10 or the sensing surface 11 . For example , a lateral extension of the light source 14 is larger than a lateral extension of one detector unit 16 . The lateral extension can mean an extension along a direction parallel or at least approximately parallel to a main extension plane of the cover 10 . For example , the lateral extension of the light source 14 is similar to the lateral extension of the cluster 18 .

[0105] Alternatively, not shown, it is also possible , that multiple cluster 18 of the plurality of clusters 18 or all clusters 18 share a common global light source 14 . Figure 11 shows an input device 3 for generating touch input according to an exemplary embodiment . The input device 3 comprises a part with a structured outer surface 21 . The structure 22 comprises ridges 23 and valleys 24 . In particular, the structure 22 is configured to be deformed under force . The input device 3 can be the obj ect 2 touching the device 1 or the sensing surface 11 .

[0106] For example , the input device 3 comprises a refractive index which is at least approximately equal to the refractive index of a human skin . The structure 22 may comprise or may be formed of silicone . Shown here , the input device 3 is a glove .

[0107] Figures 12A, 12B and 12C show schematic views of structures 22 of an input device 3 according to exemplary embodiments . A cross-section of the structure 22 can resemble or comprise a wave-shape , Figure 12A, a triangular shape , Figures 12B and 12C, or a sawtooth-shape , not shown . Preferably, the crosssection of the structure 22 is not rectangular . In particular, the shape of the ridge 23 may be non-rectangular , such that an ef ficient deformation of the structure 22 under force or pressure can be obtained .

[0108] Figure 13A, 13B and 13C show schematic views of a method for force touch sensing using an input device 3 according to an exemplary embodiment . The structure 22 of the input device 3 shown here comprises a triangular cross-section . Apart from this , the di f ferent touches or the steps of the method for force touch sensing shown here correspond to the schematic views of the exemplary embodiment shown in Figures 3A, 3B and

[0109] 3C . Figure 14 shows a schematic view of a method for force touch sensing according to a comparative example. Thereby, an object 2, e.g. a finger 4, is used to move or bend a cover 10, for example a cover glass. This is indicated by the region shown below the cover 10.

[0110] The invention described herein is not limited by the description given with reference to the embodiments. Rather, the invention encompasses any novel feature and any combination of features, including in particular any combination of features in the claims, even if this feature or this combination is not itself explicitly indicated in the claims or embodiments. This patent application claims priority from German patent application 10 2024 106 002.6, the disclosure content of which is hereby incorporated by reference.

[0111] References

[0112] 1 device

[0113] 10 cover

[0114] 11 sensing surface

[0115] 12 first region

[0116] 13 second region

[0117] 14 light source

[0118] 15 detector

[0119] 16 detector unit

[0120] 17 touch grid

[0121] 18 cluster

[0122] 19 flexible substrate

[0123] 20 coating

[0124] 100 image

[0125] 2 obj ect

[0126] 21 outer surface

[0127] 22 structure

[0128] 23 ridge

[0129] 24 valley

[0130] 3 input device

[0131] 4 finger

[0132] 41 fingerprint pattern / profile

[0133] 5 emitted electromagnetic radiation

[0134] 50 reflected electromagnetic radiation

[0135] 51 scattered electromagnetic radiation

[0136] 11 first time interval

[0137] 12 second time interval

[0138] C1...C4 cluster

Claims

Claims1. Method for force touch sensing, comprising:- touching a sensing surface (11) of a device (1) with an object (2) , wherein- the object (2) comprises a structure (22) on an outer surface (21) ,- in first regions (12) of the sensing surface (11) , the structure (22) is in direct contact with the sensing surface (11) , and- in second regions (13) of the sensing surface (11) , the structure (22) is distant to the sensing surface (11) , and- determining the ratio of the first regions (12) of the sensing surface (11) to the second regions (13) of the sensing surface (11) , wherein- the structure (22) is configured to be deformed depending on a force of the object (2) on the sensing surface (11) , and- the device (1) comprises multiple sensing surfaces (11) , the sensing surfaces (11) are touched by the object (2) , and wherein an overall ratio of the first regions (12) to the second regions (13) is averaged over the ratios of the first regions (12) to the second regions (13) of the touched sensing surfaces (11) .

2. The method according to the previous claim, wherein- the touch of the object (2) is classified as force touch in case the determined ratio is above a threshold value, or- the touch of the object (2) is classified as normal touch in case the determined ratio is below the threshold value and above a further threshold value, or- the touch of the object (2) is classified as soft touch in case the determined ratio is below the further threshold value .

3. The method according to claim 1, wherein the force of the object (2) on the sensing surface (11) is proportional to a parameter to be adjusted.

4. The method according to one of the previous claims, wherein- the structure (22) of the object (2) comprises ridges (23) and / or valleys (24) ,- at the ridges (23) the structure (22) is in direct contact with the sensing surface (11) , and- the ridges (23) are flattened under the force of the object (2) on the sensing surface (11) .

5. The method according to one of the previous claims, wherein the object (2) comprises a finger (4) and the structure (22) of the object is a fingerprint pattern (41) .

6. The method according to one of the previous claims, wherein the device (1) comprises a light source (14) , configured to emit electromagnetic radiation (5) onto a side of the sensing surface (11) facing away from the object (2) , and a detector (15) , configured to detect the electromagnetic radiation (50) reflected at the sensing surface (11) .

7. The method according to the previous claim, wherein the light source (14) and / or the detector (15) comprises at least one pLED.

8. The method according to one of the claims 6 to 7, wherein the light source (14) comprises a plurality of red, green and / or blue LEDs, wherein the green LEDs illuminate the sensing surface (11) , and the red LEDs are configured to detect the reflected electromagnetic radiation (50) , during force touch sensing.

9. The method according to one of the claims 6 to 7, wherein the light source (14) emits near-infrared radiation during force touch sensing.

10. The method according to one of the previous claims, wherein the device (1) is a display fingerprint sensor.

11. The method according to one of the previous claims, wherein the sensing surfaces (11) are arranged at lattice points of a regular lattice, and a resolution of the detectors in each sensing surface is at least 200 ppi.

12. A device (1) for force touch sensing, comprising- a plurality of sensing surfaces (11) , wherein- each sensing surface (11) is configured to detect a structure (22) of an object (2) on the respective sensing surface (11) .

13. The device (1) according to the previous claim, wherein each sensing surface (11) comprises a light source (14) configured to emit electromagnetic radiation and a plurality of detector units (16) configured to detect electromagnetic radiation .

14. The device (1) according to one of the claims 12 to 13, wherein the sensing surfaces (11) are arranged on a flexible substrate (19) .

15. The device (1) according to one of the claims 12 to 14, wherein a spacing between adjacent sensing surfaces (11) is between 4 mm and 10 mm.

16. An input device (3) for generating touch input, comprising- a part with a structured outer surface (21, 22) , wherein- the structure (22) comprises ridges (23) and valleys (24) , and- the structure (22) is configured to be deformed under force .

17. The input device (3) according to the previous claim, wherein the structure (22) of the part comprises a refractive index, which is at least approximately equal to the refractive index of a human skin.

18. The input device (3) according to one of the two preceding claims, wherein the structure (22) comprises silicone .

19. The input device (3) according to one of the claims 16 to 18, wherein a cross-section of the structure (22) comprises a wave-shape, a triangular shape or a sawtooth-shape.

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