Light-emitting film, display element, and method of operating the light-emitting film

Abstract

The light-emitting film comprises a carrier, and at least one unit cell (EZ) of light-emitting diodes (LD1, LD2, LD3) is disposed on or within the carrier. The unit cells (EZ) each include a first, a second, and a third light-emitting diode (LD1, LD2, LD3). The first light-emitting diode and the second light-emitting diode of the unit cell are connected in anti-parallel to each other. The third light-emitting diode is connected in series to the parallel connection of the first light-emitting diode and the second light-emitting diode of the unit cell.

Description

[Technical Field]

[0001] The following description relates to light-emitting films, display elements, and methods of operating the light-emitting films.

[0002] This application claims priority from DE 102021130804.6 A1, the disclosure of which is incorporated herein by reference. [Background technology]

[0003] Light-emitting films, also known as "LED on film" or "light in glass," have numerous applications in industrial and consumer sectors, such as automotive, signage, transportation, or building technology. These applications include displays and design elements, among others. In technical implementations, light-emitting diodes of different colors are often connected and dynamically controlled on metallized surfaces. The light-emitting diodes, also called pixels, often form unit cells with different light-emitting colors. One example is the RGB pixel, which has pixels that can emit red, green, and blue light.

[0004] To achieve the highest possible design freedom and dynamics for each application, it is often necessary to be able to selectively control all or at least some of the light-emitting diodes. This often requires a complex arrangement of control wiring. If the light-emitting film has metallization planes, for example, a common electrode and three control wires are used for one RGB pixel. Additionally, daisy-chain ("daisy chain") connections and corresponding drive circuits are used. Until now, these solutions have usually required crossing conductor tracks or the use of integrated circuits (ICs). Alternatively, they can be connected individually, which means a large number of wires. Solutions using two or more metallization planes often use matrix connections, sometimes with multiplexing. Both solutions have the disadvantage of requiring a large number of control wires and complex connections. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of this specification is to propose a light-emitting film, a display element, and a method of operating the light-emitting film that allows for less control wiring and less complicated connections. [Means for solving the problem]

[0006] This object is achieved by the subject matter of the independent claims. Further developments and embodiments are set forth in the dependent claims and will become apparent from the following description and the drawings.

[0007] The following is based on the understanding that each feature described with respect to any embodiment can be used alone or in combination with other features described below, and, unless described as an alternative, can also be used in combination with one or more features of any other embodiment or any combination of other embodiments. Furthermore, equivalents and modifications not described below can also be used without departing from the proposed application areas, display elements, and methods of operation of the light-emitting film as defined in the appended claims.

[0008] The following presents an improved concept in the field of light-emitting films. One aspect relates to a partially anti-parallel connection of light-emitting diodes. Appropriate control of these partially anti-parallel connected light-emitting diodes allows for color mixing to generate RGB pixels, for example, on a film or glass with only one metallization surface. The advantageous connection allows for a reduction in signal wiring and thereby an increase in the transparency of the light-emitting film.

[0009] According to at least one embodiment, the light-emitting film comprises a carrier on which or within which at least one unit cell of light-emitting diodes is disposed, each unit cell including a first, second, and third light-emitting diode, the first and second light-emitting diodes of the unit cell being connected in anti-parallel with each other, and the third light-emitting diode being connected in series with respect to the parallel connection of the first and second light-emitting diodes of the unit cell.

[0010] During operation of the light-emitting film, the light-emitting diodes of the unit cells can be controlled differently. For example, a signal can be applied to the light-emitting diodes so that only one of them is active, i.e., emits light, while the other light-emitting diodes of the unit cell are inactive, i.e., do not emit light. Furthermore, a signal can be applied to the light-emitting diodes so that two light-emitting diodes each emit light simultaneously. In this way, by appropriate control, multiple light-emitting states can be obtained, for example, to display various color patterns. In particular, an inverse-parallel connection can save control wiring and require less complex connections.

[0011] Within the scope of this specification, a light-emitting diode or LED (light-emitting diode) is a semiconductor component that emits light when a current flows through it in the conducting direction. Furthermore, in addition to regular LEDs, other types of LEDs, such as OLEDs and micro LEDs, can also be used. LEDs are blocking in the reverse direction. Light-emitting diodes generate monochromatic light and may be combined to perform additive color mixing, e.g., to generate white light. Such combinations can be performed using the unit cells described above. The generated monochromatic light is hereinafter referred to as the emitted color. In this sense, red, green, and blue light-emitting diodes, so-called RGB-LEDs, are nothing more than light-emitting diodes with red, green, or blue emission colors.

[0012] The light-emitting film comprises a carrier. The unit cells or light-emitting diodes are structured on the carrier. The carrier may be, for example, a transparent film, a plastic film, a metal film, or the like. The unit cells proposed herein can be arranged on the surface of the carrier in a matrix-like manner, as a multitude of cells on or within the carrier. In this way, light-emitting films with small to large areas can be produced, enabling a multitude of applications.

[0013] According to at least one other embodiment, each unit cell has a first control wiring, a second control wiring, and a third control wiring. The first control wiring is conductively connected to a common electrode of the first light emitting diode and the second light emitting diode interconnected in anti-parallel. The second control wiring is conductively connected to a common electrode of the first light emitting diode, the second light emitting diode, and the third light emitting diode. The third control wiring is conductively connected to an electrode of the third light emitting diode.

[0014] In other words, the first control wire is connected to the common electrode of the anti-parallel LEDs, the second control wire is connected to the common electrode of all three LEDs, and finally, the third control wire is connected to the electrode of the third single LED.

[0015] In operation, each control wire is used to provide an applied signal to the light-emitting diode. The signal may include, for example, a zero potential (GND), a positive potential (+), or a negative potential (-). The signal may be applied to each control wire statically or dynamically. In this case, the term "static" indicates that the applied signal is present for a predetermined period of time, while the term "dynamic" means that the signal present on the control wire changes over a predetermined period of time.

[0016] Exemplary control with zero potential, positive potential, and negative potential can be seen from the table below, where L1, L2, and L3 represent the first, second, and third light emitting diodes, and S1, S2, and S3 represent the first, second, and third control wires on which signal combinations exist in states A through E, respectively. [Table 1]

[0017] Individual light-emitting diodes can be controlled in states A, B and C, so that only one light-emitting diode L1, L2 or L3 is active, respectively, and emits light in the respective emission color. The generation of primary colors, for example, is possible by appropriate static signals on the control wiring. Furthermore, in states D and E, the light-emitting diodes can be controlled so that only two light-emitting diodes are active, respectively, and emit light in the respective emission color. The mixing of two primary colors, for example, is possible by appropriate static signals on the control wiring.

[0018] Finally, states A to E can be dynamically implemented in a defined time relationship, whereby three light-emitting diodes are active at a defined time or period, and these three light-emitting diodes emit their respective light colors. This allows mixing of three primary colors (e.g., for the impression of white). For example, states A, B, and C, or states D and E, can be implemented in a desired time relationship by appropriate dynamic signals in the control wiring. The signals in the control wiring change over time within the "frame" for color mixing.

[0019] According to at least one alternative embodiment, the control lines form a common metallization plane, in particular exactly one common metallization plane.

[0020] The metallization planes provide two-dimensional conductive connections within the carrier. The connecting or control lines are used for connecting, i.e., current or voltage supply and signal transfer of the unit cells and light-emitting diodes.

[0021] According to the proposed concept, a common metallization plane can be used for the control of the unit cells and the light-emitting diodes, which leads to reduced cost and complexity, especially since the anti-parallel connection allows saving on control wiring.

[0022] According to at least one alternative embodiment, the unit cell includes one or more additional light emitting diodes.

[0023] According to at least one other embodiment, the light emitting diodes of a unit cell each have a different emission color. Alternatively or additionally, the light emitting diodes of a unit cell each have the same emission color. Furthermore, each two of the light emitting diodes of a unit cell can have the same emission color.

[0024] The light-emitting film may include only homogeneous unit cells having the same emission color, or may include different unit cells having different emission colors.

[0025] The emission color of the light-emitting diode can determine the emission color of the light-emitting film. In part, the emission color and its evolution over time can be determined by the signal present in the light-emitting diode during operation. The emission color of the controllably adjustable unit cell and light-emitting film is determined by the individual emission colors of the light-emitting diodes.

[0026] For example, if all the LEDs are set to emit the same emission color, the emission color of the associated unit cell is monochromatic. If two of the LEDs in a unit cell have the same emission color, the associated unit cell can emit two colors, or a mixture of two colors. This has the added advantage that, for example, one of the two LEDs with the same emission color can be reserved as a spare in case the other LED fails. Three different emission colors per unit cell allow for tuning to different primary and mixed colors.

[0027] According to at least one alternative embodiment, the light-emitting diodes of the unit cells have red, green, and blue light emission colors. In this way, the unit cells form an RGB cell. In addition to the primary colors red, green, and blue, the individual light-emitting diodes can be dynamically controlled accordingly to produce a mixed color, white.

[0028] According to at least one alternative embodiment, the carrier is flexible, thus allowing the light emitting film to be made flexible and thereby attachable to a variety of objects.

[0029] According to at least one alternative embodiment, the light emitting film includes a plurality of unit cells of light emitting diodes arranged in a row on or within a carrier.

[0030] The unit cells arranged in a row can be electrically connected, for example, by a second control wiring and thus controlled via a common control wiring. In this case, the first and third control wirings can be individually controlled for each unit cell. This allows the unit cells to be individually controlled, each of which can display primary colors and / or mixed colors as described above. By arranging them in parallel, for example, a compact display can be realized. The number of control wirings and therefore the complexity can be further reduced.

[0031] According to at least one alternative embodiment, the unit cells are arranged in a rotationally symmetrical manner in the form of successive unit cells in a row, thereby allowing for a space-saving arrangement of adjacent unit cells.

[0032] According to at least one alternative embodiment, the light emitting diodes of the unit cells are arranged in an L-shape, with consecutive L-shaped unit cells in a row being rotated relative to each other.

[0033] By arranging the L-shaped unit cells in a row, the unit cells can be interlocked in a space-saving manner. In this way, a regular arrangement of unit cells in the light-emitting film can be created. In the example of an RGB cell, for example, RGB light-emitting diodes can form a regular, continuous sub-row.

[0034] According to at least one alternative embodiment, the unit cells are arranged planarly on or within a carrier.

[0035] According to at least one other embodiment, the unit cells are arranged on or within a carrier in segments and electrically connected to one another. In operation, the segments are individually controlled by common control wiring. For example, adjacent segments in pairs share a common control wiring. Adjacent segments share one of the control wirings.

[0036] According to at least one embodiment, the display element comprises a light-emitting film according to one or more aspects proposed herein, and further, a driving circuit is provided to control the unit cells and / or light-emitting diodes via control wiring.

[0037] Additionally, a method of operating the light-emitting film is provided. All features of the light-emitting film are also disclosed for the method of operating the light-emitting film, and vice versa.

[0038] According to at least one embodiment, signals are applied to the light emitting diodes of the unit cells such that in at least one first state, only one of the light emitting diodes is active, i.e., emits light, while the remaining light emitting diodes of the unit cell are inactive, i.e., do not emit light. In at least one second state, signals are applied to the light emitting diodes such that two light emitting diodes simultaneously emit light.

[0039] According to at least one embodiment, the first state and / or the second state are statically or dynamically controlled.

[0040] Further advantages and advantageous embodiments and developments of the presented description will become apparent from the embodiments described below in conjunction with the figures.

[0041] In the exemplary embodiments and figures, components that are the same or have the same functions may be respectively provided with the same reference numerals. The illustrated elements and the size ratios of these elements relative to one another should not be considered to be essentially to scale; rather, individual elements, such as layers, components, elements, and regions, may be shown with exaggerated thicknesses or sizes for better explanation and / or understanding. [Brief explanation of the drawings]

[0042] [Figure 1] 1A-1C illustrate exemplary embodiments of light-emitting films. [Figure 2] 1A-1C illustrate exemplary embodiments of light-emitting films. [Figure 3] 1A-1C illustrate exemplary embodiments of light-emitting films. [Figure 4] 1A-1C illustrate exemplary embodiments of light-emitting films. DETAILED DESCRIPTION OF THE INVENTION

[0043] 1 shows an exemplary embodiment of a unit cell for a light-emitting film. The illustration shows a unit cell EZ having a partial anti-parallel connection of light-emitting diodes LD1, LD2, and LD3. The light-emitting diodes are RGB diodes having red, green, and blue emission colors to create an RGB cell.

[0044] The LEDs are designed as follows: the first light-emitting diode LD1 is a red light-emitting diode, the second light-emitting diode LD2 is a blue light-emitting diode, and the third light-emitting diode LD3 is a green light-emitting diode.

[0045] The light-emitting diodes are controlled using three control lines S1, S2, and S3. In this case, the red light-emitting diode LD1 and the blue light-emitting diode LD2 are connected in anti-parallel to each other. The first control line S1 is connected to a common electrode E1 of the red light-emitting diode LD1 and the blue light-emitting diode LD2 connected in anti-parallel to each other. The second control line S2 is connected to a common electrode E2 of all three light-emitting diodes LD1, LD2, and LD3. The green light-emitting diode LD3 is connected to the common electrode 2 on one hand and to a third control line S3 on the other hand. For example, the green light-emitting diode LD3 is selected because it is most often required for the mixed color "white." Therefore, the green light-emitting diode LD3 is, so to speak, independent, i.e., not part of an anti-parallel connection, and therefore can be controlled more precisely. In theory, any of the three primary colors can be connected independently.

[0046] During operation, different signals or signal sequences are applied to the three control wires S1, S2, S3. For example, the signals may be zero potential (GND), positive potential (+), or negative potential (-). The combination of signals currently present defines operating states A to E. During operation, these operating states can be statically adjusted for a specific time. Thus, for example, primary colors can be represented. These operating states can also be dynamically controlled, so that the individual light-emitting diodes emit light in a specific temporal relationship, for example, creating the impression of mixed colors.

[0047] For this example of an RGB unit cell, the operating conditions can be adjusted according to the table below. [Table 2]

[0048] In operating states A, B, and C, the primary colors red, green, and blue are individually represented by corresponding light-emitting diodes LD1, LD2, and LD3. In operating states D and E, red and green (LD1 and LD3 in D) and green and blue (LD2 and LD3 in E) are jointly represented as emitting colors.

[0049] In summary, the proposed connection and control allows the implementation of the following functions: - generating the primary colors by appropriate static signals on the control wiring; - mixing the two primary colors by appropriate static signals on the control wiring, - mixing of the three primary colors (e.g. white) by appropriate dynamic signals in the control wiring, i.e. time-dependent changes of the signals in the control wiring within a "frame" for color mixing (see table); -Example: White, Operational states A, B, C in time relation, Operational states D, E in temporal relations.

[0050] The proposed unit cell allows for the use of metallized surfaces in the light-emitting film, which can reduce costs and complexity compared to other solutions. One aspect of this is the reduction of control wiring due to the anti-parallel connection of light-emitting diodes in the unit cell. Finally, the reduction of control wiring can increase the transparency of the light-emitting film (e.g., LED-on-film).

[0051] 2 illustrates an exemplary embodiment of a light-emitting film. In particular, the illustration shows an arrangement of a plurality of unit cells, such as those illustrated in connection with FIG. 1. The individual unit cells are formed in an L-shape and arranged in a row. Adjacent unit cells are rotated relative to one another so that the L-shapes alternately engage with one another, thus resulting in a rotationally symmetric arrangement of adjacent unit cells.

[0052] The unit cells are electrically connected to each other by their second control wiring S2 or share the control wiring S2. This connection is made by a common control wiring, which during operation takes the place of each second control wiring according to the above operating state. In other words, the common control wiring can be used in place of the second control wiring in the above table, and a corresponding signal can be applied. Each unit cell can further be individually controlled via its own first and third control wirings S1 and S3, for example, as shown in the table.

[0053] The proposed arrangement allows you to limit the number of contacts per column to 2 * n+1 contacts, where n is the number of RGB LEDs per column. Therefore, the total number of contacts is 2 * n+1) * m, where m denotes the number of columns. Possible applications are for example small displays (eg with segments).

[0054] FIG. 3 shows another exemplary embodiment of the light-emitting film. The connection corresponds to the example of FIG. 2. The difference is that three light-emitting diodes LD1 to LD3 with only two different emission colors are provided in one unit cell. Two light-emitting diodes have the same emission color. In this case, LEDs of the same color are spatially arranged close to each other between consecutive unit cells due to an L-shaped and rotationally symmetrical arrangement. Adjacent LEDs of the same color can be used as backups (same adjacent ones).

[0055] FIG. 4 shows another exemplary embodiment of a light-emitting film. In this example, multiple unit cells (here, three of each illustratively) are integrated into one segment SG. The unit cells of the segment are connected by a common second control wiring, similar to the series connection in FIGS. 2 and 3. The respective unit cells can be configured in an L-shape and connected to one another, as described in connection with FIG. 1. Furthermore, the respective first and third control wirings S1 and S3 are connected to one another. Thus, the unit cells of one segment are switched together (not independently). Finally, there are three control wirings for one segment, and these three control wirings are controlled by signals as shown in the table above.

[0056] Adjacent segments share control wiring S2, but are not switched simultaneously. The control wiring shared by the segments changes. In Figure 4, S3 is the common wiring between SG1 and SG2, while S1 is between SG2 and SG3. For the operation of all segments, 1:2 (every other segment) multiplexing can be implemented with appropriate drive circuits. The shape of the segments can be formed very arbitrarily. The number of contacts is 2 * There are n+1 segments, where n is the number of segments. Possible applications are pictograms or surface displays.

[0057] The foregoing description sets forth numerous specific details of features. These should not be construed as limitations on the scope of the improved concepts or of what may be claimed, but rather merely as exemplary descriptions of features specific to particular embodiments of the improved concepts. Certain features described herein in the context of individual embodiments can be implemented in combination in a single embodiment. Conversely, some features described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable combination. Furthermore, although the features described above are described as interacting in a particular combination, and even originally claimed as such, one or more features of a claimed combination can, in some cases, be extracted from the combination, and the claimed combination may be subject to subcombinations or variations of the subcombination.

[0058] Although processes may be shown in a particular order in the figures, this should not be understood as requiring that these processes be performed in the order shown, or in sequential order, or that all of the processes shown be performed to achieve desired results. In certain circumstances, a different order or parallel processing may be advantageous.

[0059] A series of embodiments have been described. Nevertheless, various modifications may be made without departing from the spirit and scope of the improved concepts. Accordingly, other embodiments are within the scope of the following claims. [Explanation of symbols]

[0060] E1 electrode E2 electrode EZ unit cell LD1 Light Emitting Diode LD2 Light Emitting Diode LD3 Light Emitting Diode S1 control wiring S2 control wiring S3 control wiring SG Segment

Claims

1. A light-emitting film comprising a carrier on which or in which several unit cells (EZ) of light-emitting diodes (LD1, LD2, LD3) are arranged, - the unit cells (EZ) respectively include a first light-emitting diode, a second light-emitting diode, and a third light-emitting diode (LD1, LD2, LD3), - the first and second light-emitting diodes of the unit cell (EZ) are connected in anti-parallel with each other, and the third light-emitting diode is connected in series with the parallel connection of the first and second light-emitting diodes of the unit cell; Each unit cell (EZ) is a first control wiring (S1) conductively connected to the common electrode (E1) of the first and second light-emitting diodes connected in antiparallel; a second control wiring (S2) conductively connected to the common electrode (E2) of the first light-emitting diode, the second light-emitting diode and the third light-emitting diode; a third control wiring (S3) conductively connected to the electrode of the third light-emitting diode, the unit cells (EZ) are arranged in a row on or in the carrier and are electrically connected to each other by their second control wirings (S2), and each unit cell (EZ) is individually controlled via its first and third control wirings (S1, S3); or - said unit cells (EZ) are arranged in segments (SG) planarly on or in said carrier and are electrically connected to each other by their first control wiring (S1), their second control wiring (S2) and their third control wiring (S3), so that said unit cells (EZ) of one segment are switched together; - the segments (SG) are individually controlled by the second control lines (S2), and - a light-emitting film characterized by adjacent segments sharing one of said first control wiring (S1) and said third control wiring (S3), so that adjacent segments are not switched simultaneously.

2. 2. The light-emitting film of claim 1, wherein the control wirings (S1, S2, S3) form a common metallization plane.

3. 10. The light-emitting film of claim 1, wherein the unit cell (EZ) comprises one or more further light-emitting diodes.

4. - the light-emitting diodes of a unit cell each have a different emission color; - the light-emitting diodes of a unit cell each have the same emission color, or 10. The light-emitting film of claim 1, wherein each two of the light-emitting diodes of a unit cell have the same emission color.

5. 10. The light-emitting film of claim 1, wherein the light-emitting diodes of the unit cell (EZ) have emission colors of red, green, and blue.

6. The light-emitting film of claim 1 , wherein the carrier is flexible.

7. 2. A light-emitting film according to claim 1, wherein the unit cells (EZ) are arranged in the row on or in the carrier with rotational symmetry.

8. - the light emitting diodes of the unit cells are arranged in an L-shape; The light-emitting film according to claim 1, wherein the consecutive L-shaped unit cells in a row are rotated relative to each other.

9. A display element, - a light-emitting film according to claim 1; a driver circuit for controlling said unit cells and / or said light-emitting diodes by control wiring.

10. 1. A method for operating a light-emitting film, the light-emitting film comprising a carrier on which or within which several unit cells each consisting of a light-emitting diode are disposed, the method comprising: - the unit cells (EZ) each include a first light-emitting diode, a second light-emitting diode, and a third light-emitting diode; the first and second light-emitting diodes of the unit cell (EZ) are connected in anti-parallel with each other, and the third light-emitting diode is connected in series with the parallel connection of the first and second light-emitting diodes of the unit cell; Each unit cell (EZ) is a first control wiring (S1) conductively connected to the common electrode (E1) of the first and second light-emitting diodes connected in antiparallel; a second control wiring (S2) conductively connected to the common electrode (E2) of the first light-emitting diode, the second light-emitting diode and the third light-emitting diode; a third control wiring (S3) conductively connected to the electrode of the third light-emitting diode, The method includes applying a signal to the light emitting diode of the unit cell, such that: a signal is applied to the light emitting diodes such that, in at least a first state, only one of the light emitting diodes is active, i.e., emits light, while the remaining light emitting diodes of the corresponding unit cell are inactive, i.e., do not emit light; and - signals are applied to the light-emitting diodes such that, at least in a second state, the two light-emitting diodes of the corresponding unit cell emit light simultaneously; the unit cells (EZ) are arranged in a row on or in the carrier and are electrically connected to each other by their second control wirings (S2), and each unit cell (EZ) is individually controlled via its first and third control wirings (S1, S3); or - said unit cells (EZ) are arranged in segments (SG) planarly on or in said carrier and are electrically connected to each other by their first control wiring (S1), their second control wiring (S2) and their third control wiring (S3), so that said unit cells (EZ) of one segment are switched together; - the segments (SG) are individually controlled by the second control lines (S2), and - adjacent segments share one of said first control wiring (S1) and said third control wiring (S3), so that adjacent segments are not switched simultaneously.

11. The method of claim 10 , wherein the first state and / or the second state are statically or dynamically controlled.

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