A display device comprising a transparent display ele ment, such as an inorganic thin film electrolumines cent (TFEL) display element or a thin film organic light emitting diode (OLED) display element, may be provided with various types of input devices for con trolling an information processing system connected with the display device.

For example, an electrical display device may comprise a touch-sensitive input device laminated onto a dis play element. However, addition of a touch-sensitive input device or element onto a display element in creases the complexity of the structure and manufac turing of the latter, and may also impair the optical properties of the display element.

From a functional point of view, a transparent display element may be configured to operate two- directionally, thus to display information to both sides thereof. In such case, feasibility of touch- based interactivity of the display element may strong ly depend on the detailed configuration and way of op eration of the touch-sensitive device, element, or ar rangement. In light of this, it may be desirable to develop new solutions related to displays and touch- sensitive input devices thereof.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form that are further de- scribed below in the Detailed Description. This Sum mary is not intended to identify key features or es sential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

According to a first aspect, a display arrangement is provided. The display arrangement comprises a trans parent thin film display element with a layer struc ture extending substantially along a base plane defin ing a lateral extension of the display element.

The thin film display element comprises an emissive layer configured to emit light in consequence of elec trical voltage coupled over the emissive layer; a first patterned conductor layer, on a first side of the emissive layer, comprising a first display elec trode; a second patterned conductor layer, on a second side of the emissive layer opposite the first side, comprising a second display electrode at least partly laterally overlapping the first display electrode; and a touch-sensing element comprising a first touch elec trode and a second touch electrode formed in the first and second patterned conductor layers, respectively.

The display arrangement further comprises a control unit configured to measure touch-dependent capacitive coupling for at least one of the first and second touch electrodes, said measuring comprising supplying a time-dependent measurement voltage signal to the touch-sensing element, and, when supplying the meas urement voltage signal to the touch-sensing element for measuring the touch-dependent capacitive coupling for one of the first and second touch electrodes, to supply a shielding voltage signal to the other touch electrode to decrease an effect of a touch from the side of said other touch electrode on the touch- dependent capacitive coupling for said one touch elec trode .

According to a second aspect, a method for touch de tection using a thin film display element is provided, wherein the thin film display element is in accordance with the first aspect or any embodiment thereof dis closed in this specification.

The method comprises measuring touch-dependent capaci tive coupling for at least one of the first and the second touch electrodes, said measuring comprising supplying a time-dependent measurement voltage signal to the touch-sensing element, and, when supplying the measurement voltage signal to the touch-sensing ele ment for measuring the touch-dependent capacitive cou pling for one of the first and the second touch elec trodes, supplying a shielding voltage signal to the other touch electrode to decrease an effect of a touch from the side of said other touch electrode on the touch-dependent capacitive coupling for said one touch electrode .

It is specifically to be understood that a control unit in accordance with the first aspect may be con figured to control a thin film display element using a method in accordance with the second aspect or any em bodiment thereof disclosed in this specification. BRIEF DESCRIPTION OF DRAWINGS

The present disclosure will be better understood from the following detailed description read in light of the accompanying drawings, wherein:

FIG. 1 depicts a partly cross-sectional, schematic illustration of a display arrangement,

FIG. 2 shows a schematic illustration of a display arrangement,

FIG. 3 depicts a partly cross-sectional, schematic illustration of a display arrangement,

FIG. 4 shows a schematic illustration of a display arrangement,

FIG. 5 depicts a double-sided display panel,

FIG. 6 shows a car, one particular type of vehicle, comprising a window assembly configured as a windscreen, and

FIG. 7 illustrates a method for touch detec tion using a thin film display element.

Unless specifically stated to the contrary, any draw ing of the aforementioned drawings may be not drawn to scale such that any element in said drawing may be drawn with inaccurate proportions with respect to oth er elements in said drawing in order to emphasize cer tain structural aspects of the embodiment of said drawing .

Moreover, corresponding elements in the embodiments of any two drawings of the aforementioned drawings may be disproportionate to each other in said two drawings in order to emphasize certain structural aspects of the embodiments of said two drawings.

DETAILED DESCRIPTION

Concerning display arrangements and methods discussed in this detailed description, the following shall be noted .

Herein, a "display", or a "display panel", may refer to a device, e.g., electronic device, configured to present data or imagery. The aforementioned terms may be understood broadly in the context of this specifi cation, naturally covering displays capable of dis playing various patterns, images, or text, but also, for example, various control panels and user interface elements with at least one emissive area for emitting light therefrom.

Further, a "display arrangement" may refer to an ar rangement which may form, as such, a complete, opera ble display. Alternatively, a display arrangement may be used as a part of a complete display comprising al so other elements, units, and/or structures. A display arrangement may generally comprise at least one dis play element.

Throughout this specification, a "display element" may refer to an element comprising at least one emissive area for emitting light therefrom in order to present visual information.

Herein, "light" may refer to electromagnetic radiation of any wavelength ( s ) within a range of relevant wave lengths. The range of relevant wavelengths may overlap or coincide with ultraviolet (wavelength from about 10 nanometers (nm) to about 400 nm) , visible (wave length from about 400 nm to about 700 nm) , and/or in frared (wavelength from about 700 nm to about 1 millimeter (mm) ) parts of electromagnetic spectrum.

FIG. 1 depicts a partly cross-sectional, schematic il lustration of a display arrangement 100 according to an embodiment. Although not explicitly shown in FIG. 1, the embodiment of FIG. 1 or any part thereof may generally comprise any features and/or elements of any of the embodiments of FIGs. 2 to 6 which are omit ted from FIG . 1.

In the embodiment of FIG. 1, the display arrange ment 100 comprises a transparent thin film display el ement 101 with a layer structure extending substan tially along a fictitious base plane 102 defining a lateral extension of the thin film display ele ment 101.

Herein, a "layer" may refer to a generally sheet- formed element arranged on a surface or a body. Addi tionally or alternatively, a layer may refer to one of a series of superimposed, overlaid, or stacked gener ally sheet-formed elements. A layer may generally com prise a plurality of sublayers of different materials or material compositions. A layer may be path- connected. Some layers may be locally path-connected and disconnected.

In this disclosure, a base plane "defining a lateral extension" of an element with a layer structure may refer to said element comprising a layer and having lateral directions along said base plane, in which lateral directions said element may have dimensions substantially larger than in a thickness direction perpendicular to said lateral directions.

Herein, a "thin film" display element may refer to a display element having a total thickness less than or equal to 50 ym, or less than or equal to 20 ym, or less than or equal to 10 ym. Individual layers may have thicknesses, for example, in a range from a few nanometers to some hundreds of nanometers or some mi crometers .

Throughout this specification, an element or material being "transparent", may refer to a quality, i.e., "transparency", of said element or material of allow ing light of wavelength ( s ) within a range of relevant wavelengths to propagate through such element or mate rial. Said range of relevant wavelengths may generally depend on intended usage of such transparent element or material.

Transparency of an element with a layer structure may refer to a capability of said element to transmit a main portion of irradiance of light within a range of relevant wavelengths incident on said element along an initial propagation direction intersecting a base plane of said element. A transparent element with a layer structure may transmit, for example, 50 % or more, or 80 % or more, of irradiance of light energy incident onto it at a range of relevant wavelengths. An element may transmit light and substantially main tain an initial propagation direction thereof. Such maintaining of initial propagation direction of light may refer to optical clarity of said element. The base plane 102 of the embodiment of FIG. 1 is pla nar. In other embodiments, a thin film display element may be curved, extending substantially along a curved base plane. Further, although illustrated as a planar structure in FIG. 1, the thin film display element 101 may be formed as a rollable, flexible, and/or bendable structure. Consequently, a base plane may generally be variable .

In the embodiment of FIG. 1, the thin film display el ement 101 comprises an emissive layer 103. The emis sive layer 103 is configured to emit light in conse quence of electrical voltage coupled over the emissive layer 103.

In this specification, an "emissive layer" may refer to layer comprising material capable of emitting light when electrical voltage is coupled over said emissive layer .

The thin film display element 101 of the embodiment of FIG. 1 further comprises a first patterned conductor layer 104 on a first side of the emissive layer 103. Any thin film display element, such as the thin film display element 101 of the embodiment of FIG. 1, may generally be implemented as any suitable type of dis play element. As such, said any display element may generally comprise any number of suitable sublayers or additional layers.

Throughout this specification, a "conductor" may refer to an electrical conductor material and/or the elec trical conductivity thereof. Consequently, a "conduc tor layer" may refer to a layer comprising a conductor material. Additionally or alternatively, a conductor layer may be electrically non-insulating, e.g., elec trically conductive.

A conductor layer may comprise, for example, indium tin oxide (ITO), aluminum-doped zinc oxide (AZO, ZnO:Al), any other appropriate transparent conductive oxide (TCO) , and/or any other transparent conductor material. Additionally or alternatively, a conductor layer may comprise, for example, a thin metal mesh. Such layers, with sufficiently low thicknesses, may be transparent .

Herein, a "patterned" layer may refer to a layer ex tending non-uniformly throughout an extent thereof. Additionally of alternatively, a patterned layer may refer to a structure comprising one or more disconti nuities. Additionally or alternatively, a patterned layer may be locally path-connected and disconnected. Additionally or alternatively, a patterned layer may comprise a hole in a topological (homeomorphism) sense .

Such patterned nature of a layer may be implemented by several patterns, the patterns being separated from each other. In some embodiments, a patterned layer may be implemented with just one pattern. Then, the "pat terned" nature of said layer may be implemented with the pattern not covering an underlying surface entire ly, i.e., at least one opening or region exists in an area of said underlying surface which is not covered by said layer. Naturally, a "patterned conductor lay er" may refer to a conductor layer with corresponding features . Any appropriate patterning processes may generally be used to pattern a patterned conductor layer. Such pat terning process may comprise several stages, such as cleaning, drying, photoresist coating, pre-baking, ex posure, developing, etching, and/or stripping with cleaning/drying steps. For example, lithographic pat terning for ITO as the material of a conductor layer may be carried out with an automated photolithography in-line tool utilizing wet-chemical processes. A se lected etchant, which may be, for example, a mixture of hydrochloric acid (HC1) and nitric acid (HNCy) , re moves the desired areas of the conductor layer.

The first patterned conductor layer 104 of the thin film display element 101 of the embodiment of FIG. 1 comprises a first display electrode 110.

Throughout this specification, a "display electrode" may refer to an electrode suitable for coupling elec trical voltage over an emissive layer. A display elec trode may be functionally, electrically, and/or gal vanically connectable to any suitable display-powering means known in the art, e.g., a display driver unit, in order to supply said electrical voltage. Addition ally or alternatively, a display electrode may at least partly, i.e., partly or entirely, laterally overlap another display electrode in order to enable coupling electrical voltage over an emissive layer.

In the embodiment of FIG. 1, the thin film display el ement 101 comprises a second patterned conductor lay er 105 on a second side of the emissive layer 103. The second side is opposite the first side. The second patterned conductor layer 105 comprises a second dis- play electrode 120. The second display electrode 120 partly overlaps the first display electrode 110. In other embodiments, a second display electrode may overlap a first display electrode at least partly. A second display electrode at least partly overlapping a first display electrode may enable coupling electrical voltage over an emissive layer.

In the embodiment of FIG. 1, the thin film display el ement 101 comprises two patterned conductor lay ers 104, 105. In other embodiments, a thin film dis play element may comprise at least one, e.g., two, or three, or more, patterned conductor layers on a first side of an emissive layer and at least one, e.g., two, or three, or more, patterned conductor layers on a second side of an emissive layer opposite the first side. In general, a thin film display element compris ing a reduced number of conductor layers may exhibit improved transparency and/or optical clarity.

Although not illustrated in FIG. 1, a transparent thin film display element may generally be formed on any appropriate substrate or carrier. Said substrate may be formed, for example, of glass, e.g., sodalime, alu minosilicate, and/or any other appropriate transparent glass, or plastic. Suitable plastic materials include, for example, polyethylene (PE) , polycarbonate (PC) , and mixtures thereof, without being limited to these examples .

A substrate or carrier may mechanically protect a thin film display element and/or serve as an electrically insulating layer between said thin film display ele ment and surroundings thereof. Further, there may also be another protective and/or insulating layer on an opposite side of said thin film display element. Such another layer may be formed by an external layer or element to which a display element is attached.

The thin film display element 101 of the embodiment of FIG. 1 further comprises a touch-sensing element and a control unit 170. The touch-sensing element comprises a first touch electrode 130 and a second touch elec trode 140. The first touch electrode 130 is formed in the first patterned conductor layer 104, and the sec ond touch electrode 140 is formed in the second pat terned conductor layer 105. The control unit 170 is configured to measure touch-dependent capacitive cou pling for at least one of the first touch elec trode 130 and the second touch electrode 140, i.e., the first touch electrode 130 and/or the second touch electrode 140. Said measuring comprises supplying a time-dependent measurement voltage signal to the touch-sensing element. In other embodiments, a control unit may be configured to measure capacitive coupling for as many touch electrodes as suitable or necessary for any given application.

In this specification, a "control unit" may refer to a device, e.g., an electronic device, having at least one specified function related to determining and/or influencing an operational condition, status, or pa rameter related to another device, unit, or element. Said device, unit, or element may herein refer to at least part of a touch-sensing element of a thin film display element. A control unit may or may not form a part of a multifunctional control system. A control unit being "configured to" perform a process may refer to capability of and suitability of said control unit for such process. This may be achieved in various ways. For example, a control unit may comprise at least one processor and at least one memory coupled to the at least one processor, the memory storing pro gram code instructions which, when executed on said at least one processor, cause the processor to perform the process (es) at issue.

Additionally or alternatively, any functionally de scribed features of a control unit may be performed, at least in part, by one or more hardware logic compo nents. For example, and without limitation, illustra tive types of suitable hardware logic components in clude Field-programmable Gate Arrays (FPGAs) , Applica tion-specific Integrated Circuits (ASICs) , Applica tion-specific Standard Products (ASSPs) , System-on-a- chip systems (SOCs) , Complex Programmable Logic Devic es (CPLDs) , etc. A control unit may generally be oper ated in accordance with any appropriate principles and by means of any appropriate circuitry and signals known in the art for capacitive touch sensing.

Herein, "touch-dependent capacitive coupling" may re fer to capacitance as a physical quantity measurable for an element or between elements. Said capacitance may generally vary based on a material distribution in the surroundings of said element (s) . Additionally or alternatively, touch-dependent capacitive coupling may refer to capacitance as an operational condition, sta tus, or parameter indicative of or representing said physical quantity. In general, changes in capacitive coupling between at least part of an electrical cir- cuit and a body extraneous to said circuit may affect an operational condition or status of said circuit. Such changes may be brought about by a touch, espe cially in case said electrical circuit comprises a touch-sensing element specifically configured for ca pacitive touch sensing. Consequently, changes in ca pacitive coupling may be associated with touch inputs, and a touch-based input arrangement may be devised based on detecting changes in capacitive coupling. Such an approach may generally be referred to as ca pacitive touch sensing.

Herein, a "touch" may refer to any change in distance between a pointing object, such as a finger, and a touch-sensing element resulting in a detectable change in coupling capacitance between said pointing object and said touch-sensing element. Additionally or alter natively, a touch may refer to any spatial arrangement of such pointing object and a touch-sensing element resulting in a detectable change in an operational condition, status, or parameter related to said touch sensing element compared to a predefined standard con dition, status, or parameter, respectively. As such, "touch sensing" may herein refer to touch and/or prox imity sensing. Further, a "touch electrode" may refer to an electrode suitable for capacitive touch sensing, and/or a "touch-sensing element" may refer to at least part of a touch sensor for capacitive touch sensing.

In this specification, "supplying a time-dependent measurement voltage signal to an element" may refer to supplying said signal to at least part of said ele ment. Specifically, in case of a touch-sensing ele- ment, said at least part may refer to at least one electrode of said touch-sensing element.

In the embodiment of FIG. 1, the control unit 170 is further configured, when supplying the measurement voltage signal to the touch-sensing element for meas uring the touch-dependent capacitive coupling for one of the first touch electrode 130 and the second touch electrode 140, to supply a shielding voltage signal to the other touch electrode to decrease an effect of a touch from the side of said other touch electrode on the touch-dependent capacitive coupling for said one touch electrode. This may facilitate utilizing the display arrangement 100 in applications requiring or benefitting from directional touch sensitivity, even in the absence of any additional layers in the thin film display element 101.

Herein, a "shielding voltage signal" may refer to a signal, which may be time-dependent, suitable for de creasing an effect of a touch from a side of a touch electrode, when supplied to said touch electrode, on a touch-dependent capacitive coupling for another touch electrode. Additionally or alternatively, a shielding voltage signal may refer to a signal with a sufficient cross-correlation with a measurement voltage signal.

In practice, supply of measurement and shielding volt age signals by a control unit may be achieved using known electrical measurement circuitry and signals. Suitable circuitry may be commercially available. Suitable signal types may generally depend on a varie ty of factors, including thin film display element type, emissive layer structure, and economical consid- erations. In some embodiments, sinusoidal and/or square voltage signals may be used as measurement and/or shielding voltage signals. In the embodiment of FIG. 1, square voltage signals are used.

In the embodiment of FIG. 1, an electrical first touch connection 171 exists between the control unit 170 and the first touch electrode 130, and an electrical sec ond touch connection 172 exists between the control unit 170 and the second touch electrode 140. There fore, the control unit 170 controls the touch-sensing element of the thin film display element 101 directly. In other embodiments, a control unit may control a touch-sensing element of a thin film display element directly, or indirectly by controlling a separate in termediate controller, which in turn is electrically connected with said touch-sensing element and carries out actual touch-sensing element control operations.

The control unit 170 of the embodiment of FIG. 1 is specifically configured, when measuring touch- dependent capacitive coupling for said one of the first touch electrode 130 and the second touch elec trode 140, to supply the measurement voltage signal to said one touch electrode, said touch-dependent capaci tive coupling being indicative of a self-capacitance of said one touch electrode. Such features may gener ally enable forming a touch-sensitive display arrange ment with directional sensitivity with a reduced num ber of electrodes and/or electrical interconnections.

Herein, "self-capacitance" of an element may refer to a physical quantity of a non-insulating body, e.g., an electrode, indicative of a ratio between added elec- trical charge in said body and an increase in electri cal potential of said body. Measurement of self capacitance may be referred to as measurement of ca pacitance with respect to infinity. In practice, meas urement of self-capacitance may refer to measuring ca pacitance with respect to electrical ground, e.g., signal ground.

Additionally or alternatively, a control unit being configured to measure capacitive coupling "indicative of a self-capacitance" may refer to said control unit being operated in accordance with principles of self- capacitive touch technology.

The control unit 170 of the embodiment of FIG. 1 is specifically configured to measure touch-dependent ca pacitive coupling for only the first touch elec trode 130. As such, in case of the embodiment of FIG. 1, said one touch electrode refers to the first touch electrode 130, and said other electrode refers to the second touch electrode 140. In other embodi ments, a control unit may be configured to measure touch-dependent capacitive coupling for at least one of a first touch electrode and a second touch elec trode, i.e., said first touch electrode and/or said second touch electrode. In said other embodiments, said touch-dependent capacitive coupling may or may not be indicative of self-capacitance ( s ) .

As shown in FIG. 1, the first touch electrode 130 and the second touch electrode 140 partly laterally over lap each other in an overlapping region 135, indicated in FIG. 1 by a bar-terminated line segment. In other embodiments, a first touch electrode and a second touch electrode may or may not at least partly later ^¬ ally overlap each other.

A first touch electrode and a second display electrode at least partly laterally overlapping each other may enhance insensitivity to touches from a side of one of said touch electrodes, when said one touch electrode is supplied with a shielding voltage signal.

In the embodiment of FIG. 1, a signal cross ^¬ correlation coefficient c _s between the measurement voltage signal and the shielding voltage signal is at least 0.8, more specifically 0.99. In other embodi ^¬ ments, a signal cross-correlation coefficient may be less than 0.8, or at least 0.8, or at least 0.9, or at least 0.95.

Signal cross correlation may be considered a measure indicative of shape or phase similarity between two signals. For example, in case of sinusoidal signals, a cross-correlation coefficient c _s corresponds to a co ^¬ sine of a phase difference between said signals. A cross-correlation coefficient c _s between two discrete ^¬ time signals x[t] and y[t] (t=l...n) may be definable as

Under practical circumstances, many signals may be treatable as discrete-time signals. In case of contin ^¬ uous signals, a cross-correlation coefficient c _s may be calculable by sampling said signals with a suffi ^¬ ciently high number of samples. Such cross-correlation coefficient c _s may correspond, for example, to a limit value achieved when said number of samples increases without bound, or an approximation representative thereof .

A signal cross-correlation coefficient c _s between a measurement voltage signal and a shielding voltage signal being at least 0.8, or at least 0.9, or at least 0.95 may significantly increase a direction- dependency of touch-sensitivity of a display arrange ment .

In the embodiment of FIG. 1, an amplitude ratio be tween highest peak-to-peak amplitudes of the measure ment voltage signal and the shielding voltage signal is in a range from 0.8 to 1.2. In other embodiments, any suitable amplitude ratios may be used. An ampli tude ratio may be indicative of a voltage level simi larity between two signals.

An amplitude ratio being in a range from 0.8 to 1.2, or in a range from 0.9 to 1.1, or from 0.95 to 1.05 may significantly increase a direction-dependency of touch-sensitivity of a display arrangement, especially in case of signals with similar shapes or phases.

FIG. 2 shows a partial view of a display arrange ment 200 according to an embodiment from a viewing di rection perpendicular to a base plane 202. Although not explicitly shown in FIG. 2, the embodiment of FIG. 2 or any part thereof may generally comprise any features and/or elements of any of the embodiments of FIGs. 1 and 3 to 6 which are omitted from FIG. 2.

In the embodiment of FIG. 2, the display arrange ment 200 comprises a segment-type thin film display element 201 with a layer structure extending substan tially along the base plane 202. The thin film display element 201 comprises a first patterned layer on a first side of an emissive layer, comprising a first display electrode 210, and a second patterned conduc tor layer, comprising a second display electrode 220 on another side of the emissive layer. In other embod iments, a display arrangement may comprise a segment- type and/or any other suitable type of thin film dis play element, such as a matrix-type thin film display element .

In this disclosure, a "segment-type" display element may refer to a display element in which emissive areas form individually or group-by-group controllable seg ments of letters, numbers, and/or other distinctive symbols. On the other hand, a "matrix-type" display element may refer to a display element in which con ductor patterns of two patterned conductor layers de fine emissive parts of an emissive layer at locations where said conductor patterns overlap. Such emissive parts of a matrix-type display element may have, for example, rectangular or square shapes. In a matrix- type display, at least one conductor pattern may be involved in defining a plurality of (e.g., at least two) emissive parts.

The thin film display element 201 of the embodiment of FIG. 2 further comprises a first touch electrode 230 and a second touch electrode 240 in the first and sec ond patterned conductor layers, respectively.

In the embodiment of FIG. 2, the display arrange ment 200 of the embodiment of FIG. 2 comprises a con trol unit 270 configured to measure touch-dependent capacitive coupling for each of the first touch elec- trode 230 and the second touch electrode 240. The con trol unit 270 is depicted schematically in FIG. 2.

A control unit being configured to measure touch- dependent capacitive coupling for each of a first touch electrode and a second touch electrode may ena ble determining whether a touch originates from a side of the first or the second touch electrode.

The first touch electrode 230 of the embodiment of FIG. 2 comprises an elongated first touch electrode trace 231, and the second touch electrode 240 compris es an elongated second touch electrode trace 241. An electrical first touch connection 271 exists between the control unit 270 and the first touch electrode trace 231, and an electrical second touch connec tion 272 exists between the control unit 270 and the second touch electrode trace 241.

The control unit 270 of the embodiment of FIG. 2 is specifically configured, when measuring touch- dependent capacitive coupling for one of the first and second touch electrodes, to supply a measurement volt age signal to said one touch electrode, said touch- dependent capacitive coupling being indicative of a self-capacitance of said one touch electrode.

As shown in FIG. 2, the first touch electrode 230 and the second touch electrode 240 partly laterally over lap each other in an overlapping region 235, high lighted in FIG. 2 by diagonal cross-hatching. An over lapping ratio between an area of the overlapping re gion 235 and an area of a union of projections of the first touch electrode 230 and the second touch elec trode 240 on the base plane 202 is at least 0.5, spe- cifically about 0.7. In FIG. 2, the union of projec tions corresponds to the parts highlighted with any type of diagonal hatching, including diagonal cross- hatching. In other embodiments, overlapping ratios may be less than 0.5, at least 0.5, or at least 0.6, or at least 0.9.

Throughout this specification, a "projection" of an element onto a base plane may refer to a result of a function-like mapping of each point in said element onto said base plane. Said mapping may correspond to a process of associating with each domain point in said element a corresponding codomain point on said base plane, such that a line perpendicularly intersecting said base plane at said codomain point passes through said domain point. In case of multiple prospective co domain points, a prospective codomain point with a shortest Euclidean distance to said domain point may be selected as the codomain point. In case of a varia ble base plane, such mapping may be conducted with said base plane being in a position with a lowest av erage curvature. Furthermore, a "union of projections" may refer to a union of such projections in a mathe matical (set theoretical) sense.

An overlapping ratio of at least 0.5, or at least 0.6, or at least 0.9 may yield significantly improved in sensitivity to touches from a side of a touch elec trodes supplied with a shielding voltage signal. Addi tionally or alternatively, insensitivity to such touches may be achievable with a reduced lateral foot print . In the embodiment of FIG. 2, the display arrange ment 200 further comprises a display driver unit 280, as illustrated schematically in FIG. 2. Additionally, the first display electrode 210 and the second display electrode 220 comprise an elongated first display electrode trace 211 and an elongated second display electrode trace 221, respectively. An electrical first display connection 281 exists between the display driver unit 280 and the first display electrode trace 211, and an electrical second display connec tion 282 exists between the display driver unit 280 and the second display electrode trace 221. The dis play driver unit 280 and the control unit 270 may or may not form sub-units of a single control system.

In other embodiments, a display arrangement may or may not comprise a display-powering means, e.g., a display driver unit. In some embodiments, a display-powering means may be implemented as a separate unit, whereas in others a display-powering means may be implemented as a sub-unit of a control system further comprising a control unit and/or any other suitable sub-units.

The thin film display element 201 of the embodiment of FIG. 2 is specifically implemented as an inorganic thin film electroluminescent (TFEL) display element. In other embodiments, a thin film display element may or may not be implemented as an inorganic thin film electroluminescent (TFEL) display element. A thin film display element may generally be implemented as any suitable type of display element.

Herein, an "inorganic thin film electroluminescent" type of display element may refer to a thin film dis- play element comprising an emissive layer comprising an inorganic phosphor material layer. In inorganic TFEL displays, an alternating or pulsed driving volt age may be applied over such emissive layer. Peak-to- peak amplitudes of such driving voltages may be, for example, few hundreds of volts, generated by a specif ic display driver unit and fed to first and second display electrodes via conductors from output termi nals of said display driver unit. In inorganic TFEL displays, a first insulating layer may be arranged be tween an emissive layer and a first patterned conduc tor layer, and a second insulating layer may be ar ranged between said emissive layer and a second pat terned conductor layer.

FIG. 3 shows a partly cross-sectional, schematic il lustration of a display arrangement 300 according to an embodiment. Although not explicitly shown in FIG. 3, the embodiment of FIG. 3 or any part thereof may generally comprise any features and/or elements of any of the embodiments of FIGs. 1, 2 and 4 to 6 which are omitted from FIG. 3.

The display arrangement 300 of the embodiment of FIG. 3 comprises a thin film display element 301 ex tending substantially along a fictitious base plane 302. The thin film display element 301 comprises a first display electrode 310 formed in a first pat terned conductor layer 304 as well as a second display electrode 320 formed in a second patterned conductor layer 305. An emissive layer 303 extends between the two patterned conductor layers. The thin film display element 301 further comprises a first touch elec trode 330 and a second touch electrode 340 formed in the first 304 and second 305 patterned conductor lay ers, respectively.

In the embodiment of FIG. 3, a control unit 370, which is schematically shown in FIG. 3, is configured to measure touch-dependent capacitive coupling for at least one of the first touch electrode 330 and the second touch electrode 340 and, when measuring the touch-dependent capacitive coupling for one of the first touch electrode 330 and the second touch elec trode 340, to feed a shielding voltage signal to the other touch electrode to decrease an effect of a touch from the side of said other touch electrode on the touch-dependent capacitive coupling for said one touch electrode. In other words, either one of the touch electrodes 330, 340 of the embodiment of FIG. 3 may receive a shielding voltage signal when capacitive coupling is measured for the other electrode.

The touch-sensing element also comprises a transmitter electrode 350 in the first patterned conductor lay er 304, and the control unit 370 is configured, when measuring touch-dependent capacitive coupling for said one touch electrode, to supply a measurement voltage signal to the transmitter electrode 350, said touch- dependent capacitive coupling being indicative of a mutual capacitance between the transmitter elec trode 350 and said one touch electrode. Such features may generally facilitate achieving higher directional sensitivity, especially in case of distant pointing obj ect ( s ) .

In other embodiments, a touch-sensing element may or may not comprise a transmitter electrode in a first and/or a second patterned conductor layer. In some em bodiments, a touch-sensing element may comprise a transmitter electrode having a first part extending in a first patterned layer, a second part extending in a second patterned conductor layer, and a connecting part connecting said first and second parts. In some embodiments, a touch-sensing element may comprise a plurality of transmitter electrodes. Generally, a transmitter electrode extending in only one patterned conductor layer may be sufficient under practical cir cumstances, especially in case of a display element having a total thickness less than or equal to 50 ym, or less than or equal to 20 ym, or less than or equal to 10 ym.

In this specification, "mutual capacitance" may refer to capacitance occurring between two electrically chargeable bodies. Additionally or alternatively, a control unit being configured to measure capacitive coupling "indicative of a mutual capacitance" may re fer to said control unit being operated in accordance with principles of projected capacitive (PCAP) touch technology. In PCAP touch technology, touch is detect ed on the basis of a change of a coupling capacitance between two touch electrodes, caused by the introduc tion and/or removal of dielectric and possibly lossy media of a touching member, e.g., a human finger, suf ficiently close to said touch electrodes.

In the embodiment of FIG. 3, an electrical first touch connection 371 exists between the control unit 370 and the first touch electrode 330, an electrical second touch connection 372 exists between the control unit 370 and the second touch electrode 340, and an electrical transmitter connection 373 exists between the control unit 370 and the transmitter elec trode 350. Therefore, the control unit 370 controls the touch-sensing element of the thin film display el ement 101 directly. In other embodiments, a control unit may control a touch-sensing element of a thin film display element directly or indirectly.

In the embodiment of FIG. 3, the first touch elec trode 330 and the second touch electrode 340 laterally overlap each other in an overlapping region 335, and an overlapping ratio between an area of the overlap ping region 335 and an area of a union of projections of the first touch electrode 330 and the second touch electrode 340 on the base plane 302 is 0.8. In other embodiments, overlapping ratios may be less than 0.5, at least 0.5, or at least 0.6, or at least 0.9.

The thin film display element 301 of the embodiment of FIG. 3 is specifically implemented as a thin film or ganic light emitting diode (OLED) display element, a particular type of TFEL display element. In other em bodiments, a thin film display element may or may not be implemented as an OLED display element.

An emissive layer of an OLED display element may gen erally comprise organic light-emitting molecules and/or polymers. Additionally, an OLED display element may comprise a number of auxiliary layers between such an emissive layer and a patterned conductor layer in order to improve an efficiency of said display ele ment. Such auxiliary layers may include electron/hole blocking, electron/hole transport, and/or elec tron/hole injection layers. In some embodiments, OLED display elements with different auxiliary layers may be used.

FIG. 4 depicts a partial view of a display arrange ment 400 according to an embodiment from a viewing di rection perpendicular to a base plane 402. Although not explicitly shown in FIG. 4, the embodiment of FIG. 4 or any part thereof may generally comprise any features and/or elements of any of the embodiments of FIGs. 1 to 3, 5, and 6 which are omitted from FIG. 4.

In particular, the display arrangement 400 of the em bodiment of FIG. 4 may be similar to that of the em bodiment of FIG. 3, comprising a thin film display el ement 401, having first and second patterned conductor layers on opposite sides of an emissive layer; a first display electrode 410 and a second display elec trode 420 extending in their respective patterned con ductor layers; a touch-sensing element comprising a first touch electrode 430 and a second touch elec trode 440 extending in their respective patterned con ductor layers, as well as a transmitter electrode 450 in the first and/or the second patterned conductor layer; and a control unit 470 configured, when measur ing touch-dependent capacitive coupling for one of the first touch electrode 430 and the second touch elec trode 440, to supply a measurement voltage signal to the transmitter electrode 450, said touch-dependent capacitive coupling being indicative of a mutual ca pacitance between the transmitter electrode 450 and said one touch electrode.

However, in the embodiment of FIG. 4, the first touch electrode 430 and the second touch electrode 440 al- most completely laterally overlap each other in an overlapping region 435, i.e., the embodiment of FIG. 4 has an overlapping ratio of about 1.

Moreover, the first touch electrode 430 of the embodi ment of FIG. 4 comprises an elongated first touch electrode trace 431, the second touch electrode 440 comprises an elongated second touch electrode trace 441, and the transmitter electrode 450 comprises an elongated transmitter electrode trace 451. An elec trical first touch connection 471 exists between the control unit 470 and the first touch electrode trace 431, an electrical second touch connection 472 exists between the control unit 470 and the second touch electrode trace 441, and an electrical transmit ter connection 473 exists between the control unit 470 and the transmitter electrode trace 441.

Further, the first touch electrode 430, the second touch electrode 440, and the transmitter electrode 450 are formed as interdigitated electrodes. In other em bodiments, touch and transmitter electrodes may or may not be formed as interdigitated electrodes. Forming touch and transmitter electrodes as interdigitated electrodes may generally improve a touch sensitivity of a display arrangement.

Finally, the display arrangement 400 further comprises a display driver unit 480, illustrated schematically in FIG. 4. Additionally, the first display elec trode 410 and the second display electrode 420 com prise an elongated first display electrode trace 411 and an elongated second display electrode trace 421, respectively. An electrical first display connec- tion 481 exists between the display driver unit 480 and the first display electrode trace 411, and an electrical second display connection 482 exists be tween the display driver unit 480 and the second dis play electrode trace 421.

FIGs. 5 and 6 illustrate exemplary products comprising display arrangements 520, 620, which may be in accord ance with any of the embodiments disclosed with refer ence to, in conjunction with, and/or concomitantly with any of FIGs. 1 to 4. Additionally or alternative ly, although not explicitly shown in any of FIGs. 5 to 7, the embodiment of either of FIGs. 5 and 6 or any part thereof may generally comprise any features and/or elements of any of the embodiments of FIGs. 1 to 4 which are omitted from a drawing depicting said embodiment .

FIG. 5 depicts a double-sided display panel 500 ac cording to an embodiment. The double-sided display panel 500 comprises a transparent screen 510 and a display arrangement 520. The display arrangement 520 comprises a thin film display element 521, a control unit 522, and a display driver unit 523, one particu lar type of display-powering means.

Herein, a "double-sided" display panel may refer to a display panel comprising a display element with at least one emissive area for emitting light therefrom at least to two opposite directions in order to pre sent visual information at least to two mutually oppo site sides of said display panel. A double-sided dis play panel may generally be transparent. The thin film display element 521 of the embodiment of FIG. 5 is laminated on the screen 510. In other embod iments, a thin film display element may be laminated or otherwise coupled to a screen. In some embodiments, a screen may have a layer structure with a first and a second layer, and a thin film display element may be arranged between said first and second layers.

A double-sided display panel may generally further comprise a frame 530, as indicated in FIG. 5 by dashed lines. In embodiments comprising a frame, a control unit and/or a display-powering means may be arranged at least in part inside said frame.

In some embodiments, a double-sided display panel may correspond to a window assembly. Throughout this spec ification, a "window assembly" may refer to a unit comprising a screen and a display arrangement coupled together and configured to be mountable to a wall or a roof of a building or a vehicle for covering an open ing therein.

FIG. 6 shows a car 600, one particular type of vehi cle, according to an embodiment. The car 600 comprises a window assembly 610 comprising a display arrange ment 620 with a thin film display element 621, a con trol unit 622, and a display driver unit 623. In other embodiments, a vehicle may or may not correspond to a car. A "vehicle" may herein refer to any machine con figured to transport people or cargo. Consequently, the term "vehicle" may refer, for example, to a car, a bicycle, a motorcycle, a train, a ship, an airplane, a helicopter, a spacecraft, or any variation or hybrid thereof, without limiting the scope of the term to these specific examples.

The window assembly 610 of the embodiment of FIG. 6 is configured to function as a windscreen of the car 600. In other embodiments, a window assembly may be config ured to function as a windscreen or any other type of window .

In the embodiment of FIG. 6, the window assembly 610 comprises a first curved sheet of safety glass and a second curved sheet of safety glass laminated together using a plastic layer, and the thin film display ele ment 621 is arranged between the first and second curved sheets of safety glass. In other embodiments, a window assembly may have a structure identical, simi lar, or different to the window assembly 610 of the embodiment of FIG. 6.

Above, mainly structural and material aspects of dis play arrangements and products comprising display ar rangements are discussed. In the following, more em phasis will lie on method aspects related to touch de tection. What is said above about the ways of imple mentation, definitions, details, and advantages relat ed to the structural and material aspects applies, mu- tatis mutandis, to the method aspects discussed below. The same applies vice versa.

FIG. 7 illustrates a method 700 for touch detection using a thin film display element, which may be in ac cordance with any of the embodiments disclosed with reference to, in conjunction with, and/or concomitant ly with any of FIGs. 1 to 6. The method 700 of the embodiment of FIG. 7 comprises the compulsory (i.e., non-optional ) processes of meas uring touch-dependent capacitive coupling 710 for one of a first touch electrode and a second touch elec trode of a touch-sensing element of the thin film dis play element, said measuring comprising supplying a time-dependent measurement voltage signal 711 to the touch-sensing element, and, when supplying the meas urement voltage signal to the touch-sensing element for measuring the touch-dependent capacitive coupling for said one of the first and the second touch elec trodes, supplying a shielding voltage signal 720 to the other touch electrode to decrease an effect of a touch from the side of said other touch electrode on the touch-dependent capacitive coupling for said one touch electrode.

In the embodiment of FIG. 7, the method 700 further comprises the optional processes of measuring touch- dependent capacitive coupling 730 for said other touch electrode, said measuring comprising supplying a time- dependent measurement voltage signal 731 to the touch sensing element, and, when supplying the measurement voltage signal to the touch-sensing element for meas uring the touch-dependent capacitive coupling for said other touch electrode, supplying a shielding voltage signal 740 to said one touch electrode to decrease an effect of a touch from the side of said one touch electrode on the touch-dependent capacitive coupling for said other touch electrode.

Consequently, the method 700 of the embodiment of FIG. 7 constitutes an example of a method for touch detection using a thin film display element comprising measuring touch-dependent capacitive coupling for each of a first touch electrode and a second touch elec trode of a touch-sensing element of the thin film dis play element.

In an embodiment, a method for touch detection using a thin film display element comprises steps implementing processes corresponding to the processes 710, 711, 720, 730, 731, 740 of the method 700 of the embodiment of FIG. 7. In other embodiments, a method for touch detection using a thin film display element may com prise steps implementing processes corresponding to the compulsory processes 710, 711, 720 of the meth od 700 of the embodiment of FIG. 7.

Generally, steps of a method for touch detection using a thin film display element implementing processes corresponding to any of the processes 710, 711, 720, 730, 731, 740 of the method 700 of the embodiment of FIG. 7 need not be executed in any fixed order. Fur thermore, a method for touch detection using a thin film display element may generally comprise any number of additional processes, steps, and/or features that are not disclosed herein in connection to the meth od 700 of the embodiment of FIG. 7.

For example, in an embodiment, each touch-dependent capacitive coupling is indicative of a self capacitance of a touch electrode. In another embodi ment, a touch-sensing element comprises a transmitter electrode in a first and/or a second patterned conduc tor layer and each touch-dependent capacitive coupling is indicative of a mutual capacitance between the transmitter electrode and a touch electrode. Irrespective of the means used for carrying out a method for touch detection using a thin film display element, any steps of the method may be performed at least partially automatically by means of suitable computing and/or data-processing means. Such means may comprise, for example, at least one processor and at least one memory coupled to the processor. The at least one memory may store program code instructions which, when run on the at least one processor, cause the processor to perform steps implementing various processes of the method. Additionally or alternative ly, at least some of those steps may be carried out, at least partially, by means of some hardware logic elements or components, such as Application-specific Integrated Circuits (ASICs) , Application-specific Standard Products (ASSPs) , or System-on-a-chip systems (SOCs) , without being limited to these specific exam ples .

It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The in vention and its embodiments are thus not limited to the examples described above, instead they may vary within the scope of the claims.

It will be understood that any benefits and advantages described above may relate to one embodiment or may relate to several embodiments. The embodiments are not limited to those that solve any or all of the stated problems or those that have any or all of the stated benefits and advantages. The term "comprising" is used in this specification to mean including the feature (s) or act(s) followed thereafter, without excluding the presence of one or more additional features or acts. It will further be understood that reference to 'an' item refers to one or more of those items.