Substrate comprising electrodes and light modulator with reduced diffraction

Abstract

A substrate for an optical modulator is disclosed. The substrate may include at least one drive electrode applied to the substrate. The drive electrode is arranged in a pattern across the substrate. The pattern of multiple drive electrodes across the substrate includes multiple repeating building blocks. The electrodes in the building blocks form at least one drive electrode.

Description

Technical Field

[0001] The presently disclosed subject matter relates to light modulators, substrates, light modulator methods, and computer readable media. Background Art

[0002] Optically active glass is known in the prior art. Typically, an optically active glass system comprises two parallel plates made of a transparent dielectric material, such as glass or a plastic material. The internal volume defined between the plates can be subdivided into a plurality of small independent volumes or individual cells filled with a dielectric fluid. The fluid contains a suspension of particles of a dielectric material, a charged or chargeable material. The faces of the two plates facing each other carry electrodes facing each other. The electrodes are connected to a power source associated with a control device.

[0003] The electrodes of each plate are formed by pairs of interlaced combs. The electrodes of the two interlaced combs can be subjected to voltages of the same or opposite polarity. By applying appropriate voltages to the electrodes, the particles can be concentrated at different locations between the electrodes, giving the system a transparent or opaque appearance.

[0004] There are a number of disadvantages associated with the known system. When the known glass is in a transparent configuration, the electrodes applied to the plate can cause diffraction effects. Diffraction effects are undesirable for glass. In certain circumstances, the presence of diffraction effects can also be detrimental to safety. For example, if the optically active glass is applied to a vehicle (such as an automobile), the presence of diffraction can confuse or distract the operator of the vehicle.

[0005] Reference is made to the published international patent application W02008012934A1, entitled "DISPLAY DEVICE AND METHOD OF MANUFACTURING THE SAME".

[0006] Refer to US patent US11099451 B1, entitled "Light modulator, substrate including electrodes and smart glass".

[0007] Reference is made to the published international patent application W02021228907A1, entitled “Smart glass based on electrophoresis and scattering particles”.

[0008] Refer to US patent US2014160412 A1, entitled "Lateral electric field type liquid crystal display device with non-uniform spacing between two electrodes".

[0009] Refer to "Non-uniform sampling and wide range angularspectrum method" by YONG-HAE KIM ET AL. Summary of the invention

[0010] It would be advantageous to provide an improved substrate provided with electrodes and a light modulator comprising such an improved substrate which solves these and other problems. The inventors have found that the electrode design in known systems can lead to diffraction. Solving this problem leads to substrates for use with less diffraction.

[0011] A substrate for use in an optical modulator may include a plurality of interdigitated drive electrodes applied to the substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate. The drive electrodes are electrically isolated from each other so that voltages on the drive electrodes can be independently controlled.

[0012] When such a substrate is used in a light modulator, a varying voltage applied to the electrodes may cause electrophoretic movement of particles in an optical layer between two such substrates. This movement, in turn, causes modulation of the light shining through the substrate. Typically at least two such substrates are used, each having at least two drive electrodes, but additional substrates and / or drive electrodes may be used. The light modulator is preferably electrophoretic, but may also be dielectrophoretic. A substrate according to an embodiment may also be used in other technologies, such as OLED or electrowetting. A substrate according to an embodiment may be combined with another substrate according to an embodiment, but this is not necessary; one or both of the substrates may be transparent. In glass applications, typically both substrates are transparent.

[0013] Optically active glasses, in particular so-called smart glasses, are important applications for light modulators, for example embodiments of substrates on which multiple interdigitated electrodes are applied. Typically, all substrates in a light modulator are transparent; this is particularly true in glass applications. In one embodiment, one or more substrates may be translucent. In one embodiment, one substrate may be opaque while the opposing substrate is transparent or translucent. Such light modulators change the appearance of incident light. The substrate may be reflective.

[0014] For applications such as glass, an important issue is diffraction. Diffraction is preferably reduced to a smaller number. Diffraction can be calculated with a number called a pixelation noise metric, which is the ratio of the maximum intensity of all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum. See, for example, the paper Murray, Ian B., Densmore, V., Bora, V., Pieratt, WM, Hibbard, DL, and Milster TD's "Numerical comparison of grid pattern diffraction effects through measurement and modeling with OptiScan software". Proc. SPIE 8016, Window and Dome Technologies and Materials XII, 80160U (2011), which is included herein by reference. It has been proven difficult to further reduce the pixelation diffraction value using traditional patterning of electrode lines. However, the inventors have found a way to overcome this obstacle and have produced a design that breaks the existing obstacles. In an embodiment, the pixelation noise metric of the drive electrode pattern of the calculated substrate is less than 6.05%, or less than 5%, or less than 4%. Specifically, the pixelation noise metrics of the building blocks may be below these thresholds.

[0015] In one embodiment, the pattern of the drive electrode is formed by a plurality of repeated building blocks. The building block includes interdigitated electrodes. By making the building blocks repeat next to each other, the electrodes on the building blocks form the drive electrodes. For example, before the entire pattern is deposited on the substrate, the building blocks can be fused into the pattern in the mask layout tool. The building blocks can be partially overlapped. For example, if the electrode circuit of the first building block overlaps with the electrode circuit of the adjacent building block (both belong to the same drive electrode), these electrode circuits of the two building blocks can be fused. In one embodiment, the building block is surrounded by a drive bus, which is advantageously merged with the bus of the same drive electrode of the adjacent building block.

[0016] In one embodiment, a drive bus is arranged at one side of the substrate for each drive electrode to drive the drive electrode. The drive electrode may also connect isolated electrodes to the drive electrode in other ways. The drive bus may in turn be connected to a controller.

[0017] The drive buses may be placed only at sides of the substrate, but may also extend across the substrate, for example between building blocks or as part of a building block. For example, multiple straight drive buses may extend across a building block, and arms may extend from the drive buses to further connect electrodes to the drive electrodes. Preferably, it is avoided that two drive buses extend across the substrate in close proximity to each other, as this would form narrow trenches that may have a negative impact on diffraction. If two drive electrodes are used, the drive buses advantageously alternate between the building blocks.

[0018] In one embodiment, the building block may include a plurality of interdigitated electrodes extending in at least two directions across the building block. The inventors have found that using electrodes having a relatively long length relative to the size of the building block is beneficial for reducing diffraction. For example, for at least one electrode of the plurality of interdigitated electrodes in the building block, the maximum length between any two points on the electrode measured along the electrode in the building block is at least twice the length of the diagonal of the building block unit.

[0019] In one embodiment, a building block may include a plurality of branching nodes at which electrodes branch. For example, at least three electrode lines may be connected to one branching node. Introducing a cluster of branching nodes increases the local variability of the electrodes and increases the electrode length compared to a building block diagonal. For example, a cluster of branching nodes may include at least a first branching node that is directly connected to a second branching node and a third branching node via an electrode line. In one embodiment, the cluster may be larger, for example, a first branching node is directly connected to two additional branching nodes, which in turn are directly connected to four branching nodes.

[0020] The clusters of nodes together with the electrode lines connecting them may form a tree. More generally, the drive electrodes may be a tree.

[0021] Although the inventors have found an algorithm that can generate a pattern with a large number of branch nodes, clusters of such branch nodes can be manually introduced into the electrode pattern. For example, the drive electrode can be found by calculating the spanning tree of the Voronoi pattern. A complementary electrode pattern can be formed by placing edges that travel across the edges removed from the Voronoi pattern. Instead of the Voronoi pattern, other subdivision surfaces can be used. For example, a regular subdivision surface can be used, possibly using one or more polygonal shapes. The subdivision surface can be randomized by randomly shifting the edges of the subdivision surface. The spanning tree of the randomized subdivision surface can be used as an electrode; the complementary electrode can be formed by a dual graph.

[0022] Building blocks can be repeated across substrates by copying and translating the blocks (without mirroring or rotating). However, in one embodiment, isometry is applied to building blocks, such as mirroring, rotation and / or point reflection. Although multiple building blocks can also be used, the advantage of using isometry is that the placement of building blocks can be improved without having to optimize multiple blocks. For example, if a drive bus across the substrate is used (e.g., between building blocks), isometry can be used to avoid placing the drive buses next to each other on the substrate. For example, a whole row or column of building blocks can be mirrored in its longitudinal direction to form the next row or column of building blocks, and so on. The advantage of mirroring building blocks like that is that drive buses can be merged between different building blocks, thereby avoiding grooves between them. The advantage of mirroring building blocks is that a symmetrical electrode design for a substrate can be established, which is conducive to manufacturing an optical modulator.

[0023] In one embodiment, the tiles are arranged in a tessellation, where each tile may be mirrored or dot-reflected. In one embodiment, the tiles are not tessellated, but the edges of the tiles are parallel or orthogonal to each other.

[0024] A substrate according to an embodiment can be used for a light modulator (also referred to as an optical modulator). For example, two such substrates can be arranged relative to each other so that charged particles suspended in a fluid between the substrates can be moved by applying a voltage to the electrodes. Typically, the electrode designs of the bottom substrate and the top substrate are identical, but this is not necessary. Similarly, the two electrode designs are usually aligned with each other, but this is also not necessary. The particles can absorb or reflect light. The reflection can be specular reflection or diffuse reflection, or between specular reflection and diffuse reflection. The particles can emit light, for example, with phosphorescence or fluorescence.

[0025] Light modulators provide a panel that can change transparency or reflectivity. In one embodiment, the color or color intensity can be changed, etc. Light modulators can be used as covers, such as covers for containers (e.g., closets, cabinets, etc.). Depending on the specific application, light modulators are also called ambient light modulators, dynamic light modulators, light modulators, color modulators, IR modulators, UV modulators, IR active filters, UV active filters, or dynamic color filters.

[0026] One particularly advantageous application is in optically active glass, which is also referred to in the art as smart glass, smart window, controllable glass, optical panel, electronic signage, dynamic light panel, dynamic color panel, active color panel, active light panel, active light surface, active color surface, dynamic light surface, or dynamic color surface.

[0027] In one embodiment, the controller is configured to apply an electric potential to electrodes on the substrate of the light modulator to obtain an electromagnetic field between the electrodes. The electromagnetic field provides electrophoretic movement of particles toward or away from the electrodes. As the position of the particles changes, the optical properties of the panel also change, for example, the transparency or reflectivity of the panel changes. If the particles are colored, the color of the panel will also change. By changing the paired electrodes between which the field is established, the particles can move in the desired direction. What the inventors have found is that the control of the light modulator is not necessarily limited to only changing the field applied between the electrodes, but can also include changing the maximum amplitude. It should be noted that the use of alternating current is beneficial. For example, by driving with a lower maximum amplitude, the rate of change of the light modulator is changed. For example, when driving to a desired target transparency or target reflectivity, this is advantageous, and the maximum amplitude can be reduced to avoid overshoot. When starting to drive to the target transparency or target reflectivity, the maximum amplitude can also be increased alternatively. For example, the controller can be configured to obtain one of multiple transparency levels or reflectivity levels of the light modulator by using an alternating current or alternating voltage with one of multiple maximum amplitudes. The above relationship may be represented by an algorithm or the like. The relationship between transparency level or reflectivity level and maximum amplitude may be controlled by a look-up table, for example indicating a sequence of maximum amplitudes to drive towards transparency or reflectivity. It should be noted that an alternating voltage may also be used.

[0028] In addition to changing the electrodes between which the signal is applied, changing the maximum amplitude of the drive signal can also be used to improve balanced drive. For example, the power (e.g., maximum amplitude) applied to some electrodes may be different from the power applied to other electrodes. For example, the controller can be configured to apply a potential difference between subsequent electrodes on the same substrate while applying a potential difference between opposing electrodes on opposing substrates.

[0029] In one embodiment, at least one of the two substrates is according to an embodiment. The other substrate may have one or more electrodes, or may be free of electrodes. In one embodiment, the superposition of electrodes on the substrates satisfies a bound on the ratio of the length of the electrode to its diameter in the building block, or a bound on the pixelation noise ratio, for example, such bounds as indicated herein. Instead of diameter, other measurements can generally be used for the size of the building block. For example, in the case of a rectangular building block, an average of the sides of the building block can be used, such as the harmonic mean of the sides of the building block.

[0030] In one embodiment, there are at least two electrodes on each substrate, but there may be more than two electrodes. For example, at least three electrodes are applied to at least one of the first substrate and the second substrate. For example, in one embodiment, the first substrate may be applied with two electrodes and the second substrate may be applied with three electrodes. Typically, the opposing substrates are mirror images so that the electrode lines are opposite to each other; however, this is not necessary, and different effects are possible when the electrodes are not arranged in this way.

[0031] Another aspect of the invention is a building comprising a light modulator according to an embodiment. Another aspect of the invention is a car comprising a light modulator according to an embodiment. For example, the car and / or the building may include a light modulator and a controller configured to control the transparency or reflectivity of the light modulator by controlling the voltage on the electrodes of the light modulator, the controller being electrically connected to the light modulator or capable of being electrically connected to the light modulator.

[0032] The light modulator is an electronic device that can be driven by a power source, for example, under the control of a controller. For example, the controller can instruct the power source to apply a specific waveform to a specific electrode to achieve various transparency or reflectivity effects or to smear the above effects.

[0033] An embodiment of the method may be implemented on a computer as a computer-implemented method, or may be implemented in dedicated hardware, or a combination of the two. The executable code of an embodiment of the method may be stored on a computer program product. Examples of computer program products include: a memory device, an optical storage device, an integrated circuit, a server, online software, etc. Preferably, the computer program product includes a non-transitory program code stored on a computer-readable medium for implementing an embodiment of the method when the program product is executed on a computer.

[0034] In one embodiment, the computer program comprises computer program code, which is suitable for performing all or part of the steps of an embodiment of the method when the computer program is run on a computer. Preferably, the computer program is implemented on a computer readable medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Further details, aspects, and embodiments will be described below, by way of example only, with reference to the accompanying drawings. The elements in the drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. In the drawings, elements corresponding to elements already described may have the same reference numerals. In the drawings:

[0036] Figure 1a schematically illustrates an example of an embodiment of a building block,

[0037] Figure 1b An example of an embodiment of a substrate is schematically shown,

[0038] Figure 1c An example of an embodiment of a substrate is schematically shown,

[0039] Figure 1d An example of an embodiment of a substrate is schematically shown,

[0040] Figure 1e schematically illustrates an example of an embodiment of a building block,

[0041] Figure 1f schematically illustrates an example of an embodiment of a building block,

[0042] Figure 1g An example of an embodiment of a substrate is schematically shown,

[0043] Figure 1h An example of an embodiment of a substrate is schematically shown,

[0044] Figure 2a Schematically shows an example of an embodiment of an electrode,

[0045] Figure 2b Schematically shows an example of an embodiment of an electrode,

[0046] Figure 2c Schematically shows an example of an embodiment of an electrode,

[0047] Figure 3 An example of an embodiment of a substrate is schematically shown,

[0048] Figures 4a to 4i An example of an embodiment of a substrate is schematically shown,

[0049] Figure 5a and Figure 5b An example of an embodiment of a substrate is schematically shown,

[0050] Figure 6a schematically illustrates an example of an embodiment of a building block,

[0051] Figure 6b An example of an embodiment of a substrate is schematically shown,

[0052] Figure 6c An example of an embodiment of a substrate is schematically shown,

[0053] Figure 6d An example of an embodiment of a substrate is schematically shown,

[0054] Figure 7a schematically illustrates an example of an embodiment of a light modulator,

[0055] Figure 7b schematically illustrates an example of an embodiment of a light modulator,

[0056] Figure 7c An example of an embodiment of a motor vehicle is schematically shown,

[0057] Figures 8a to 8c schematically shows an embodiment of a light modulator,

[0058] Figure 9a schematically shows a computer-readable medium, the writable portion of which comprises a computer program according to one embodiment,

[0059] Figure 9b schematically shows a representation of a processor system according to one embodiment,

[0060] Figures 10a to 10d schematically illustrates aspects of an embodiment of a light modulator,

[0061] Fig.11 schematically shows a cross section of an embodiment of a light modulator,

[0062] Fig.12a schematically shows an embodiment of a light modulator,

[0063] Figure 12b to Figure 12c schematically shows an embodiment of a light modulator,

[0064] Fig.13a schematically illustrates an example of an embodiment of a building block,

[0065] Fig.13b An example of an embodiment of a substrate is schematically shown,

[0066] Figure 14a to Figure 14h An embodiment of a substrate is schematically shown.

[0067] Reference numerals list

[0068] The following list of symbols and abbreviations is provided to facilitate understanding of the drawings and should not be construed as limiting the claims.

[0069] 10. Optical Modulator

[0070] 11. First substrate

[0071] 12. Second substrate

[0072] 13, 13a, 13b Electrode

[0073] 14, 14a, 14b Electrode

[0074] 15 Fluid

[0075] 16 Controller

[0076] 30 pcs

[0077] 20 Car

[0078] 21. Optical Modulator

[0079] 40 Optical Modulator

[0080] 41 First substrate

[0081] 42 Second substrate

[0082] 43 Third substrate

[0083] 46 Controller

[0084] 100-102 base plate

[0085] 111-114 Main Line

[0086] 121-124 Main Line

[0087] 131-134 Interdigital Electrode

[0088] 140 Building Blocks

[0089] 141-144 Building Blocks

[0090] 110, 120 drive bus

[0091] 110', 120' drive bus

[0092] 119, 129 connection area

[0093] 151-157 Points on one side of the building block

[0094] 160 Building Blocks

[0095] 161,162 Local building blocks

[0096] 171, 172 Building Blocks

[0097] 191, 192 Direction

[0098] 201-207 nodes

[0099] 210-218 nodes

[0100] α1-α7 angle

[0101] 221-222 Electrode circuit

[0102] 180 substrate

[0103] 181 A point on the substrate

[0104] 182 First closest distance

[0105] 183 Second closest distance

[0106] 188 first driving electrode

[0107] 189 Second driving electrode

[0108] 601 Building Blocks

[0109] 602-604 base plate

[0110] 640 Groove

[0111] 611-622 Building Blocks

[0112] 651-662 Building Blocks

[0113] 720 First Electrode

[0114] 730 Second Electrode

[0115] 740 Edge Seal

[0116] 750 Spacer

[0117] 760 Semiconductor Ink

[0118] 772,774 substrates

[0119] 812 First drive bus

[0120] 814 Second drive bus

[0121] 820 building blocks

[0122] 902-906 drive bus part

[0123] 912 driving electrode

[0124] 1000,1001 Computer readable medium

[0125] 1010 Writable part

[0126] 1020 Computer Programs

[0127] 1110 Integrated Circuit

[0128] 1120 Processing Unit

[0129] 1122 Memory

[0130] 1124 ASIC

[0131] 1126 Communication Components

[0132] 1130 Interconnect

[0133] 1140 Processor System DETAILED DESCRIPTION

[0134] Although the presently disclosed subject matter may be implemented in many different forms, one or more specific embodiments thereof will now be shown in the drawings and described in detail herein, it being understood that the contents of this disclosure should be considered as examples of the principles of the presently disclosed subject matter and are not intended to limit the subject matter to the specific embodiments shown and described.

[0135] Hereinafter, for ease of understanding, the elements of the embodiments are described in operation. However, it is apparent that the various elements are arranged to perform the functions described by them. In addition, the subject matter disclosed herein is not limited to the embodiments, but also includes the combination of each other feature described herein or described in the mutually different dependent claims.

[0136] A substrate is disclosed, for example for use in an optical modulator. The substrate may include a plurality of interdigitated drive electrodes applied to the substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate. The pattern of the plurality of drive electrodes across the substrate includes a plurality of repeating building blocks.

[0137] Figure 1b An example of an embodiment of a substrate is schematically shown. The substrate is particularly useful for a light modulator, such as a light modulator of the type described herein. A plurality of interdigitated drive electrodes are applied to the substrate across the substrate.

[0138] An exciting example use of the substrate is in an electrophoretic light modulator. Typically, an electrophoretic light modulator includes at least two substrates, each substrate having at least two drive electrodes; however, this is not required, for example, an electrophoretic light modulator may include a single substrate having 2 electrodes and an opposing substrate having 1 electrode. In any case, preferably, at least one substrate in the light modulator is according to an embodiment.

[0139] An embodiment of the light modulator includes a first substrate according to an embodiment and a second substrate. The first substrate and the second substrate are arranged with their inner sides facing each other. At least one drive electrode is applied to the inner side of the first substrate. The optical layer is arranged between the first substrate and the second substrate. The controller is configured to apply an electric potential to the at least one drive electrode, thereby causing modulation of the optical properties of the light modulator. One or both of the first substrate and the second substrate are transparent and / or translucent.

[0140] There are many different kinds of optical modulators that use at least one drive electrode applied to a substrate. Interference is a common problem in the field of optical modulators because light is transmitted through the substrate. The optical layer and controller can be arranged to modulate the optical properties using effects that depend on the potential on the drive electrode; embodiments include dielectrophoretic effects and electrophoretic effects. For example, the optical modulation can include modulation of particles arranged in the optical layer. The number of drive electrodes can range from one drive electrode on a single substrate to multiple drive electrodes on one or two substrates.

[0141] The optical layer disposed between the first substrate and the second substrate may include particles, for example particles suspended in a fluid. The controller may be configured to apply an electrical potential to the drive electrodes, causing the particles to move, thereby modulating an optical property of the light modulator.

[0142] In one embodiment, the particles include charged particles or chargeable particles, and the controller is configured to apply an electric potential to the drive electrode to obtain an electromagnetic field that provides electrophoretic movement of the particles. In one embodiment, the electromagnetic field is arranged between at least two drive electrodes, and the at least two electrodes are arranged on the same substrate or on different substrates.

[0143] In one embodiment, the particles include dielectric particles, and the controller is configured to apply an electric potential to the drive electrode to apply an electric field gradient to the particles so that the particles can move under the influence of dielectrophoretic forces.

[0144] The controller may apply an electrical signal to one or more drive electrodes. Embodiments for controlling the dielectrophoretic force may use signals including DC signals and / or AC signals. Embodiments for controlling the electrophoretic force may use signals including DC signals and / or AC signals.

[0145] A number of known light modulators are reviewed below, showing some options in terms of technology and electrodes.

[0146] US Patent 10921678, entitled 'Electrophoretic device', incorporated herein by reference, shows an electrophoretic device having only one patterned electrode on one of the two substrates. For example, the one substrate with electrodes according to US10921678 can be replaced with a substrate according to one embodiment including a single electrode. US Patent 8054535B2 (incorporated herein by reference) and US Patent 8384659B2 (incorporated herein by reference) show alternative embodiments of electrophoretic light modulators in one of the two substrates having two patterned electrodes.

[0147] Patterned electrodes are also used in dielectrophoretic optical modulators. For example, U.S. patent applications US2005185104A1 (incorporated herein by reference) and US20180239211A1 (incorporated herein by reference) show a dielectrophoretic optical modulator having a substrate with patterned electrodes. Any of these referenced electrophoretic or dielectrophoretic optical modulators can be tuned by patterning electrodes on a substrate according to an embodiment.

[0148] In one embodiment, the optical modulator includes a first substrate and a second substrate. At least one of the first substrate and the second substrate may be according to an embodiment. For example, the first substrate and the second substrate may be arranged so that the inner sides are opposite to each other. Using a substrate according to an embodiment has the effect of, for example, reducing optical interference. The optical layer is arranged between the first substrate and the second substrate. The drive electrode is arranged to modulate the electric field in the optical layer. The optical layer includes a fluid, the fluid including particles, wherein the particles are charged or can be charged. The particles can move under the control of the electric field. For example, the controller can be configured to apply an electric potential to the drive electrode to obtain an electromagnetic field at the drive electrode to provide electrophoretic motion of the particles toward or from one of the at least one drive electrodes, thereby causing modulation of the optical properties of the optical modulator.

[0149] The paper "Reversible Metal Electrodeposition Devices: An Emerging Approach to Effective Light Modulation and Thermal Management" (incorporated by reference) also shows a substrate on which a patterned electrode is applied. The patterned electrode may be advantageously arranged according to one embodiment, for example, to reduce interference.

[0150] One embodiment of the substrate can be used in an electrochromic device (ECD). An electrochromic device (ECD) controls optical properties such as light transmission, absorption, reflection, and / or emission in a continuous but reversible manner when a voltage is applied (electrochromism). This property enables electrochromic devices to be used in applications such as smart glass, electrochromic mirrors, and electrochromic display devices.

[0151] For example, an electrochromic device is described in the paper "Silver grid electrodes for faster switching ITO free electrochromic devices" by António Califórnia et al., which is incorporated herein by reference. The paper describes the preparation of an electrochromic device, in this case an electrochromic device without ITO.

[0152] Electrochromic devices use conductive electrodes applied to a substrate. The cited paper uses a silver grid made using silver ink as the conductive electrode. The electrochromic device may include an electrochromic material. The cited paper uses poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). In the electrochromic device, at least one drive electrode (e.g., a conductive electrode) is applied to a substrate. The drive electrodes are arranged in a pattern across the substrate. The cited paper discloses two different grid patterns: a regular honeycomb and a regular trapezoidal design. See Tables 1 and 2 of the cited paper. Figure 3 .

[0153] Electrodes can be applied to a substrate (in the case of the cited paper, polyethylene terephthalate (PET)) by screen printing on the substrate. The electrodes are typically conductive materials, such as metals or metal oxides. In the cited paper, grids were screen printed on PET using a RokuPrint RP 2.2 device and a 180-wire screen using silver ink. The samples were allowed to dry in an oven at 130°C for 15 minutes. On top of these silver grids, one or two layers of PEDOT:PSS SV3 were then printed by screen printing.

[0154] Electrochromic devices experience interference due to the combination of a regular pattern (e.g., honeycomb or trapezoidal patterns in the cited paper) and light passing through. One way to avoid interference is to use a pattern according to an embodiment, for example, one in which the electrodes are very long compared to other repeating elements (e.g., building blocks).

[0155] For example, the metal grid used in the cited paper can be replaced by drive electrodes applied to a substrate, the drive electrodes are arranged in a pattern across the substrate, the pattern of drive electrodes across the substrate includes a plurality of repeating building blocks, the building blocks include one or more electrodes extending in at least 2 directions across the building blocks, the electrodes in the building blocks form at least one drive electrode, and for at least one of the electrodes in the building blocks, the maximum length between any two points on the electrode measured along the electrode in the building block is at least 2 times the length of the diagonal of the building block unit. Instead of requiring a minimum length for the electrode, the pattern can use other features that reduce interference, such as high branching, such as branching the electrode into two or more paths, the branching being repeated multiple times, such as at least 2 times, 3 times, 4 times or more, resulting in the initial electrode bifurcating into at least 4, 8, 16 or more electrodes.

[0156] Another embodiment of an electrochromic device is given in U.S. Patent 5,161,048, entitled "Electrochromic Window with Metal Grid Counter Electrode and Acidic Polyelectrolyte", which is incorporated herein by reference. For example, an electrochromic device may include a transparent electrochromic film and an ion conductive layer disposed between a pair of electrodes. Metal grid electrodes are distributed for the electrodes. FIG. 1 of the patent shows a metal grid according to the cited patent. To form a counter electrode, the metal grid is disposed adjacent to a second glass substrate.

[0157] For example, in one embodiment of the electrochromic device, the electrochromic device may include a transparent substrate, a conductive electrode member, a transparent electrochromic film in contact with the conductive electrode member, an ion conductive polymer in contact with the electrochromic film; and a patterned conductive electrode in contact with the ion conductive polymer. The patterned conductive electrode may be a patterned conductive electrode according to one embodiment.

[0158] The substrate according to an embodiment may be beneficially applied in many other technologies. For example, the light modulator may be a dielectrophoretic light modulator, such as shown in US20050185104A1, which is incorporated herein by reference. The substrate in an embodiment may also be used in other electrowetting and OLED applications.

[0159] In OLED and electrowetting, electrodes are only required on one of the substrates. The substrate with the electrodes may be according to one embodiment.

[0160] In applications where the light modulator is used in glass, both substrates are usually transparent. In other applications (such as in televisions, e-readers, etc.), only one substrate may be transparent.

[0161] Figure 1b Shown in FIG. 1 are two drive electrodes on the same surface. Figure 1b In the figure, two driving electrodes are indicated by two different dashed line styles. There can be more than two electrodes on the same side of the substrate, for example to facilitate more fine-grained control of the voltage difference across the substrate. The driving electrodes are applied to the same side of the substrate. Applying the electrodes to the substrate can be done, for example, by lithography using a mask representing the electrode pattern. The electrodes can also be applied by embedding them into the substrate.

[0162] The drive electrodes are electrically connected, for example, at the same potential everywhere. The drive electrodes may include a drive bus and a main line. At least, the main line interdigitates with the main line of another drive electrode. Typically, the drive electrodes extend across the substrate in a substantially straight line, while the main line is curled.

[0163] In one embodiment, the two substrates of the optical module each have two electrodes arranged at their inner surfaces. However, as mentioned above, multiple electrodes are not required on one or both substrates. For example, an embodiment of the optical modulator includes a first substrate and a second substrate. For example, the first substrate may include a drive electrode, and the second substrate may not include a drive electrode. For example, the first substrate may include two drive electrodes, and the second substrate may include one drive electrode. For example, the first substrate may include two drive electrodes, and the second substrate may include two drive electrodes. For example, the first substrate may include more than two drive electrodes, and the second substrate may include two or more drive electrodes.

[0164] However, an optical modulator in which each substrate includes two drive electrodes is used as an excitation embodiment. The design of a substrate featuring two drive electrodes can be adjusted to have a single drive electrode, for example, by connecting the two drive electrodes, or by removing one of the drive electrodes. Adjusting the substrate in this way can make it suitable for use with different technologies.

[0165] Each of the plurality of drive electrodes is arranged in a pattern across the substrate. The plurality of drive electrodes are arranged alternately relative to each other on the substrate. Typically, the drive electrodes include a plurality of main lines, each of which is elongated across the substrate. The main lines of the drive electrodes are alternate, for example, interdigitated with each other. For example, in Figure 1b In the embodiment, the first driving electrode includes main lines 111-114, and the second driving electrode includes main lines 121-124. Each driving electrode is driven by its driving bus. Figure 1b Two drive buses are shown: drive bus 110 and drive bus 120. The drive electrodes are also used to connect the main lines together. Figure 1bIn the embodiment, drive bus 110 drives and connects main lines 111-114; drive bus 120 drives and connects main lines 121-124. There may be more main lines than the four shown in this embodiment. The use of main lines is advantageous because it reduces the length of the electrode, but it is not necessary. It is not impossible to use only one main line for each drive electrode, but it is advantageous to have multiple main lines.

[0166] A plurality of main lines of the first electrode and the second electrode are arranged alternately relative to each other on the substrate.

[0167] One exciting application of a substrate such as substrate 100 is in smart glass (e.g., light modulators), which can be applied to home homes, offices, greenhouses, cars, etc. The transparency level or reflectivity level of the smart glass can be adjusted electronically. For example, in the smart glass, two substrates such as substrate 100 are stacked so that the sides with two electrodes applied face each other. A fluid with particles is enclosed between the two substrates. Embodiments of the smart glass will be discussed further below. In one embodiment, an electrode (e.g., two or more electrodes) is applied to one surface of each substrate. In order to facilitate, for example, stacking three or more substrates, there may also be one, two or more electrodes on another surface of substrate 100.

[0168] Some embodiments below show examples of modulating transparency levels or reflectivity levels. Light modulators can be adjusted for other optical effects. For example, if desired, the embodiment can be changed to different translucency levels instead of different transparency levels. If desired, the type of particles used in one embodiment can be changed, for example, particles that absorb or reflect different wavelengths and reflect different diffuse specular degrees. For example, in one embodiment, light modulators can modulate different reflective levels. Particles can also emit light. Stacking multiple optical layers further increases the possibilities.

[0169] Having two alternating sets of main lines is sufficient to provide an electrically adaptive glass; due to the alternation of the two sets, the electric field at any portion of the substrate can be controlled since two opposing electrodes adjoin the portion from two opposing sides.

[0170] Interestingly, the pattern in which the drive electrodes are stretched across the substrate is created by multiple repeating building blocks. Figure 1bAs shown, the drive electrodes on the substrate 100 show four blocks: blocks 141, 142, 143 and 144, which are all substantially the same. The number of building blocks can be greater than four. The building blocks are repeated in two directions across the substrate (e.g., a first direction 191 (e.g., the x direction shown horizontally in the figure) and a second direction 192 (e.g., the y direction shown vertically in the figure)).

[0171] For example, Figure 1a There is schematically shown an example of an implementation of a building block 140. The building block 140 comprises a plurality of interdigitated electrodes extending in at least two directions across the building block. Figure 1a Four electrodes are shown: electrodes 131-134. When the building block is repeated in two directions across the substrate, the electrodes in the building block will form drive electrodes, for example, forming multiple main lines of drive electrodes. Note that the building blocks are typically connected in the substrate electrode design tool. Typically, the building block includes more than four electrode lines. For example, in a series of embodiments, between 8 and 12 main lines are used. Although the number of electrode lines can be higher. For example, a building block may include many short electrode lines near the edge, and when the block is repeated, these short electrode lines will be connected to the lines of other building blocks. Taking into account these short branches, the number of lines may increase to, say, 50. Obviously, when larger building blocks are used, the number of electrode lines may also increase. In one embodiment, the number of electrode lines in the building block is between 8 and 50, or between 8 and 25, etc.

[0172] The driving electrodes formed by the repeated building blocks are connected to the driving bus. Typically, the electrode lines in a building block are connected to the electrode lines in an adjacent block by merging the corresponding electrode lines; however, this is not necessary, and connection areas connecting the corresponding electrode lines can be inserted between the repeated building blocks.

[0173] This step connects multiple main lines together to form a single drive electrode. Figure 1b Two connection areas 119 and 129 are shown, in which main lines belonging to the same drive electrode are connected to the drive bus 110 and the drive bus 120, respectively.

[0174] Will Figure 1a The electrodes shown in FIG. Figure 1b The same dashed line pattern is alternately drawn. In fact, in this embodiment, what happens is that Figure 1aA particular electrode of a building block will always end up at the first drive electrode or the second electrode, for example, as indicated in this case by the dashed line style. But this is not necessarily the case. An electrode in a building block may end up as part of the first drive electrode, or as part of the second drive electrode. This may change, for example due to the parity of the number of electrodes in the building block, the pattern in which the building block is repeated, etc.

[0175] For example, for an optical modulator with two drive electrodes, a specific pattern of repeating building blocks can be used, where alternating main lines can be assigned to two drive electrodes. However, for an optical modulator with three drive electrodes, the same pattern of repeating building blocks can be used, where each next group of three main lines can be assigned to three drive electrodes.

[0176] in addition, Figure 1a The building blocks shown in the figure are square, but this is not necessary. For example, the building blocks can be rectangular. In one embodiment, the building block shapes can form so-called subdivision surfaces. For example, the building blocks can be triangles, hexagons, or even a combination of plane-filled shapes.

[0177] As mentioned above, Figure 1a and 1b This is especially true for the description of electrodes. Figure 1a The electrodes shown are straight, with a length equal to the length of one side of the building block. However, in one embodiment, the electrodes on the building block are more curled because, for at least one electrode in the plurality of interdigitated electrodes in the building block, the maximum length between any two points on the electrode measured along the electrode in the building block is at least 2 times the length of the diagonal of the building block unit.

[0178] For example, if you use Figure 1a The electrodes are depicted schematically, then the longest possible length along the same electrode is the length of one side of the building block. Figure 1a The ratio of the longest length to the diagonal in (as schematically depicted) is However, in one embodiment, the ratio will be much larger, such as at least 2. If this value is large, it forces the electrode to follow a more winding path, which reduces diffraction. By using building blocks, the winding is distributed across the substrate. In one embodiment, the ratio between the longest lengths can even be greater than 2. For example, the ratio can be at least 3, at least 4, or at least 5, etc. This is a useful design criterion because if a long path is forced to meander across a building block because it is longer than it would be without such meandering, the angles in the path will naturally distribute and diffraction will be reduced, even if there are shorter paths in the same building block. This criterion can be enforced more strictly by calculating multiple longest paths (say, the first k longest paths in a building block), where the paths are not electrically connected. For example, k can be 2 or more, 3 or more, 5 or more, etc. For example, the first k longest paths can be required to be each longer than a multiple of the building block size (e.g., diameter), such as 2 times longer or more, 2.5 times longer or more, etc. But this stricter rule is not required to improve the design.

[0179] Typically, more than one electrode line in a building block satisfies this condition. For example, in one embodiment, a building block includes multiple electrode lines that are not electrically connected within the building block, and the longest path on each of the multiple electrodes is longer than twice the diagonal length of the building block. The number of electrodes in this multiple can be at least 2, at least 4, at least 10, etc.

[0180] Undesirable diffraction effects can be modified by adjusting the shape of the electrodes. Reducing diffraction effects is particularly important for transparent substrates, since for example diffuse reflective displays (such as might be used in an e-reader) this effect will be less noticeable. However, specular reflective displays, such as dimmable mirrors, will be affected by diffraction effects. The inventors have found that optical diffraction in a light modulator can be reduced by orienting the line shape of the electrodes at a plurality of different angles, spreading the diffraction in space and thereby reducing the intensity of the strongest diffraction point. For example, for dimmable mirrors, reducing diffraction is very important.

[0181] In one embodiment, the tunable mirror comprises a light modulator according to one embodiment. For example, the tunable mirror comprises a transparent substrate, an optical layer, and a reflective substrate. One or both of the substrates are according to one embodiment. The tunable mirror can be an electrophoretic mirror. Typically, each substrate has two electrodes, but this is not required.

[0182] Figure 1c An example of an embodiment of a substrate 101 is schematically shown. The substrate 101 is similar to the substrate 100, except for how the main lines formed by the electrodes on the building blocks are connected to the drive bus. Figure 1aIn FIG. 1 , a connection region is inserted between the repeated building blocks and the drive buses 110 and 120. In the connection region, the main lines belonging to the same drive electrode are all connected to the same drive bus. Figure 1c In the example, the drive bus is directly adjacent to the building block. To avoid the drive bus being connected to the main lines of different drive electrodes, some building blocks are modified.

[0183] For example, building block 141 may be a copy of building block 140, but with electrode 134 shortened so that main line 122, of which line 134 is a part, is not connected to bus 110. Figure 1c In , the building blocks are basically the same, except that disconnects are introduced in some electrodes of the building blocks next to the drive bus to avoid connecting the main line with the drive bus. Figure 1c All of the building blocks shown in are modified in this manner, but in one embodiment, most of the building blocks will not be modified, for example, building blocks that are not adjacent to the drive buses 110 , 120 .

[0184] Figure 1d An example of an implementation of the substrate 102 is schematically shown.

[0185] In one embodiment, the electrodes in the building blocks each connect the same opposite sides of the building blocks. This has the result that the main circuit formed by the electrodes on the building blocks connects the opposite sides of the substrate. In this case, having only two drive buses (e.g., each drive bus extends along opposite sides of the substrate) is sufficient to connect and drive the drive electrodes.

[0186] However, the electrodes in a building block do not need to connect opposite sides of the building block. While typically all electrodes in a building block will connect two sides of the building block, there is no requirement that these two sides be opposite. The reason for this is so that the electrodes can continue through the next building block. In this case, most main traces will still connect the same two opposite sides, but at the edge of the substrate this may not happen because there is no additional building block to carry the electrodes forward. To allow for more complex electrode designs on the building blocks, the main traces can be connected to the drive bus from both sides, for example, both sides of the substrate adjacent to the same corner of the substrate.

[0187] Figure 1d Shown in FIG. 1 are driving bus lines 110 ′ extending along two sides of the substrate and driving bus lines 120 ′ extending along the other two sides of the substrate.

[0188] The advantage of this configuration is that the drive buses can be manufactured on the same plane. However, this is not required. If necessary, the drive buses can be connected from three or four sides to further increase the design freedom of the building block. Various embodiments are given herein.

[0189] Note that it is allowed that the drive electrodes (e.g., drive busses) and / or main lines overlap. This is possible, for example, by introducing a portion of dielectric material between the electrodes. For example, such overlapping electrodes may be partially or fully located in different planes of the substrate.

[0190] For example, in one embodiment, a first drive electrode may be provided. Then a dielectric may be provided locally, and finally a second drive electrode may be provided. The dielectric may be arranged to cover at least the point where the first electrode and the second electrode intersect. A through hole may be used to connect the lower first drive electrode, for example, thereto. The provision of the drive electrodes may include provision of a drive bus.

[0191] Figure 1e Examples of implementations of building blocks are schematically shown. Figure 1e Two electrodes are schematically indicated in . In a practical implementation, the tracks of the electrodes shown would typically be more curved.

[0192] Figure 1e The building block of FIG. 1 shows four electrode lines, each of which is connected to at least two sides of the building block. In this case, the electrode lines do not directly connect opposite sides of the building block. There is no need to connect opposite sides of the building block, as the drive electrodes only need to be driven from one side. However, in order to cover the substrate, it is convenient if at least one or more electrodes reach the opposite side from where they are driven. This is not necessary; it is possible to make the main line electrodes reach only part of the substrate and drive them from both sides.

[0193] Figure 1eIt is shown that even if the electrode line does not connect the opposite side, the main electrode into which the specific electrode line of the building block is incorporated can still be reached across the substrate. For example, the electrode line starting at 151 on the left side is connected to the non-relative upper side of the building block at 157. If the same building block is repeated at the top of the shown building block, the main line formed by the line will continue at the point 154 of the repeated building block, and then arrive at the opposite side of the repeated building block at 152. Similarly, the electrode line starts at 155 on the left side of the building block, and the electrode line will become a part of the second drive electrode. The electrode line is connected to the upper side at 153 and continues in the repeated block at 154. Therefore, the electrode line starting from the left side of the building block may not be connected to the opposite side of the building block, but it may travel the distance in the x direction and arrive at the right side of the building block, but it is a different building block, for example, a building block above or below the shown building block. This is also possible for the y direction in reverse. In one embodiment, the main circuit connects opposite sides of the substrate in a first direction 191 (e.g., x-direction), while traveling through multiple blocks in the first direction 191 (e.g., x-direction) and at least two or more blocks in a cross-sectional direction (e.g., y-direction). Typically, the first direction 191 and the second direction 192 are orthogonal; however, this is not strictly necessary, and the two directions can be tilted relative to each other.

[0194] Figure 1f The two electrode lines in the building block shown do not need to be connected in the building block, but they can still be connected in the substrate through the connection in the adjacent building block. For example, consider the electrode on the left side, starting at point 151. The electrode is led out from the top side of the building block. Unlike the embodiment described, Figure 1e In the example, the electrode line starting from 151 is merged into the main line that is actually connected to Figure 1f , opposite side of the building block shown in .

[0195] The electrode line starting on the left side of the building block at 151 connects to the upper side of the building block at 157. If the same building block is repeated at the top of the building block shown, the electrode line will connect to the bottom side at point 156 and to the same side at a point on the bottom side at point 154. Back Figure 1f The building block shown, the electrode line continues on its upper side at point 153 and connects to the right side, ie the side opposite to the side at point 151, at point 152.

[0196] In one embodiment, a drive electrode (e.g., a main line of drive electrodes) connects a first point on a first side of a first building block to a second point on an opposite side of the same building block, and between the first point and the second point, the main line passes through at least a second building block that is immediately adjacent to the first building block.

[0197] In this example, the longest path between two points on the same electrode line is formed by the path starting at 155. According to one embodiment, the length of the longest path is a multiple of the size of the building block (e.g., one side or diagonal); for example, the longest path can be at least twice the length of the diagonal. In this example, there is only one path of this length, but there can be multiple such long paths.

[0198] An alternative requirement may be to consider paths that extend through adjacent building blocks. For example, the longest path starting at one side (e.g., the left side) and connecting to the opposite side of the same building block may be a multiple of the diagonal of the building block; the path may travel through adjacent building blocks. Using this definition, a slightly higher threshold value, such as two, may be used, but higher threshold values ​​are also possible, such as three.

[0199] In one embodiment, an electrode line on a building block connects two points on the same side.

[0200] In one embodiment, an electrode line on a building block connects two points on different, non-opposing sides of the building block.

[0201] Figure 1f Also shown in FIG. 1 are electrode lines connecting two opposite sides of a building block. In one embodiment, all electrode lines on a building block connect opposite sides of the building block. However, as shown, this is not necessary. Typically, the drive bus is straight, while the main line is curled.

[0202] Figure 1g Examples of embodiments of substrates are schematically shown. Figure 1g A variation of using building blocks to tile the substrate is shown in Figure 1g , the building blocks are staggered. For example, in a first direction 191, such as in the x-direction, the building blocks 160 are arranged in a row. At the top of the building blocks, the building blocks are also arranged in a row, but the building blocks are offset from the row below. The offset is shown as half a block, but it could also be another fraction of the building block width, such as 1 / 3 of the building block width.

[0203] If a rectangular base plate is desired, partial building blocks can be added to the rows to fill the base plate. Figure 1g 1 and 162. Building blocks 161 and 162 can be identical to half of substrate 160, but more typically they are designed to connect drive electrodes to the cover layer of the substrate. As shown, each row has partial building blocks, such as building blocks 161 in odd rows, and building blocks 162 in even rows. However, it is possible to have a staggered design but have partial building blocks at the beginning and end of, say, even rows, and only use full building blocks in alternating, say, odd rows.

[0204] Other subdivision surfaces (e.g., substrate fill tiling) can be used to create electrode patterns. For example, in one embodiment, the building blocks are parallelograms, rhombuses, etc. In one embodiment, the building blocks can be arranged in rows, where in odd rows, the building blocks are mirrored, e.g., flipped; sometimes called sliding reflection symmetry. In addition to mirroring, the building blocks can also be point reflected or inverted.

[0205] Figure 1h An example of an embodiment of a substrate is schematically shown. Figure 1b or Figure 1c As in , the building blocks are repeated across the substrate in at least two directions. However, in Figure 1h In, several different building blocks are used; Figure 1h Two building blocks 171 and 172 are shown. Blocks 171 and 172 are repeated in two directions (e.g., a first direction 191 and a second direction 192). Figure 1h In the example, building block 171 is not directly adjacent to building block 171, for example, the two building blocks form a checkerboard filling. However, this is not necessary, for example, a first building block may be connected to a copy of a first building block at two opposite sides, but connected to a second building block at another two opposite sides. There may be more than two different building blocks.

[0206] Using different tiles, for example alternating adjacent tiles in different directions, increases design flexibility, which can be used, for example, to ensure continuity of tiles supplied to the interior of the substrate, while connections to a controller can be established at the edge of the substrate.

[0207] Note that in the electrode scheme, a tile can be powered by an adjacent tile. For example, in a checkerboard mosaic of building blocks, one building block can power the next building block. This can also include different tile layouts. For example, vertically adjacent and / or horizontally adjacent tiles can be different. In one embodiment, a portion of the checkerboard is repeated and a portion includes different tiles. For example, consider 5 adjacent tiles, such as center, left, right, top and bottom; these tiles can be different or repeated, but are preferably configured to connect electrode lines to electrode lines in adjacent tiles and / or to an overall drive bus.

[0208] Figure 2a An example of an embodiment of an electrode is schematically shown; in a substrate, the electrode is part of a single drive electrode. For example, Figure 2a The electrodes shown in can be part of an electrode circuit in a single building block. The electrodes shown can also be formed by multiple building blocks that are adjacent to each other. For example, Figure 2a or Figure 2bThe clusters shown in may be part of main lines 111-114, 121-124 or electrode lines 131-134.

[0209] The electrode comprises a plurality of nodes where the electrode branches. Branching nodes 201, 202 and 203 are shown. The nodes are electrically and directly connected by electrode lines. One such electrode line between branching node 201 and branching node 203 is shown with reference numeral 221.

[0210] It was found that having multiple branching nodes in the electrode is beneficial to increase the ratio between the electrode length and the building block diagonal, which is beneficial to reduce diffraction. Clusters with branching nodes cause the electrodes to form more different angles, which helps to reduce diffraction.

[0211] In one embodiment, the main lines and even the driving electrodes form a tree, such as an undirected acyclic graph. Preferably, the tree contains many branching nodes. The advantage of branching nodes is that they allow the introduction of angles between electrode lines. For example, Figure 1a A branching node 201 is shown, which is directly connected to two further branching nodes: node 202 and node 203. The electrodes branch at all three nodes 201-203.

[0212] Figure 2b An example of an embodiment of an electrode is schematically shown. This example describes in detail Figure 2a 7 branch nodes of the electrode are shown. Branch node 201 is directly connected to branch node 202 and branch node 203. Branch nodes 202 and 203 are also each connected to two other branch nodes. Branch node 202 is connected to branch node 204 and branch node 205. Branch node 203 is connected to branch nodes 206 and 207. The direct connection between branch nodes 203 and 206 is indicated by reference numeral 222.

[0213] Figure 2a or Figure 2b The branching patterns increase the ratio between the electrode length and the building block diameter or diagonal. These branching patterns also increase the diversity of electrode line directions and reduce the long elongation of parallel electrode lines. Such improvements are still valuable without helping the ratio. For example, in one embodiment, a substrate for an optical modulator is provided, wherein the substrate includes:

[0214] - A plurality of interdigitated drive electrodes (111-114, 121-124) applied to a substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate, wherein the electrodes on the substrate include a plurality of nodes located at electrode branches, the nodes being electrically connected via electrode lines, the plurality of nodes and the connecting electrode lines forming a tree, the electrodes including at least a first node (201), at which the electrode branches into at least three electrode lines, the first node (201) being directly connected to a second node (202) and a third node (203) via the electrode line, the electrode branching into at least three electrode lines at the second node and the third node.

[0215] Figure 2c An example of an embodiment of an electrode is schematically shown; in a substrate, the electrode is part of a single drive electrode. For example, Figure 2c The electrodes shown in the figure may be part of an electrode circuit in a single building block. The electrodes shown may also be formed by multiple building blocks that are next to each other.

[0216] Eight nodes are shown: nodes 210-218 that are directly connected to the electrode lines. Figure 2c Not all of these nodes are shown to branch off. In fact, not all nodes need to be branch nodes. For example, a node may connect two electrode lines at an angle.

[0217] For example, the path from 210 to 218 can be the maximum length path between any two points on the electrode, such as from point 210 to 218. Along the path from node 210 to node 218, the subsequent electrode lines form an angle. These angles are denoted as α1 to α4. For example, α1 is the angle between the electrode line from node 210 to 211 and the electrode line from node 211 to node 212.

[0218] To reduce diffraction, it is preferred that the angles in the design are non-uniform. For example, the angles along the path (e.g., the longest path) may be randomly selected, or the angles along the path may be selected to uniformly sample the range of possible angles in the range of 0 to 360 degrees. For example, in one embodiment, the angles are selected so that an angle is selected 30 degrees from at least each block. For example, an angle may be selected from the range 1-30, 31-60, ... 331-360. Long paths have an effect on diffraction; having many angles in a long path will make the path less uniform and thus reduce diffraction. Measurements may also be done by first reducing all angles modulo 180.

[0219] Instead of limiting the angles along the path, all angles at the nodes in the building block can also be included. For example, a node connecting N electrode lines defines n-1 angles between consecutive electrode lines. In addition, for these angles, it is preferred that they are uniform and represent the entire angle range. For example, they can be randomly selected, or selected to sample the entire angle range, such as from 0 to 180 degrees.

[0220] The nodes are preferably selected to cover the building blocks, and hence the substrate. For example, the nodes may be randomly selected across the building blocks.

[0221] Note that the electrode lines between nodes can be straight or curved. Having straight lines makes the design calculations easier, but curved designs provide more flexibility that can be used to combat diffraction. For example, Figure 3 In a curved design, one might limit the angle considerations to the branching nodes. In one embodiment, the substrate is curved and the plurality of repeating building blocks comprises at least two different shapes.

[0222] Figure 3 An example of an embodiment of a substrate 180 is schematically shown. A detail of two drive electrodes is shown: electrode 188 and electrode 189. The detail shown may for example be part of a building block. The detail may also be formed by two building blocks arranged next to each other.

[0223] Figure 3 An embodiment of an electrode comprising a curved electrode line is shown. The following considerations also apply to designs using straight electrode lines.

[0224] Figure 3 180 shows a point 181 on the substrate which is not located on an electrode. At this point, it is desired to control the electric field so that the electrophoretic motion of particles in the optical layer adjacent to the substrate 180 can be controlled. For clarity, the point 181 is indicated as a small disk.

[0225] For a point such as point 181, the distance to the two closest electrodes can be calculated. The closest distance between an electrode and point 181 can be considered to be the minimum distance between any point on the electrode and point 181. For example, for point 181 and electrode 189, the closest distance is obtained at 183. For example, for point 181 and electrode 188, the closest distance is obtained at 182. The distance is calculated as Euclidean distance.

[0226] For example, the desired goal when patterning electrodes is as follows.

[0227] The closest distance from any point in the substrate (e.g., point 181) to the first drive electrode and the second drive electrode should be below the threshold. For example, both distance 183 and distance 182 should be below the threshold. Such a threshold is preferably maintained across the entire substrate, for example, across the entire portion of the particle motion to be controlled. Having a limit on the distance that can be removed from the electrode will impose limits on the attenuation of the electric field at the point from the electrode. The value of the threshold depends on the intensity of the electric field, the uniformity of the desired optical effect, the speed and uniformity of the transition between different optical states, etc. As an embodiment, the threshold can be set to 50 microns.

[0228] Another way to limit the deviation of the electrodes from each other is to limit the sum of the closest distances to the first drive electrode and the second drive electrode, for example requiring that these distances should be below a first threshold. For example, the sum of distances 182 and 183 is below the first threshold. If the two electrodes deviate too much from each other, there may be a slow region between them in which neither electrode has much effect, for example, both electric fields are overly attenuated. The appropriate threshold again depends on the specific application, but as an example, 100 microns can be used as the first threshold.

[0229] At the same time, it may also be desirable to avoid electrodes being too close to each other. For example, if the electrodes on the substrate are too close to each other, the likelihood of an accidental short circuit may increase. For example, the sum of distance 182 and distance 183 may be required to be at least a second threshold. The appropriate value of the second threshold depends on the application. As an example, the second threshold may be taken as 10 microns.

[0230] The upper and lower limits of the distance between the electrodes can be calculated for any point on the substrate, and appropriate limits can be set for them according to the instructions. In order to simplify the calculation, the distance from the point on the first drive electrode to the point on the second drive electrode can be required to be at least the second threshold. For example, this distance can also be taken as 10 microns.

[0231] For electrode patterns where the electrode lines are lines, the calculations can be further simplified by restricting the calculations to nodes (including the endpoints of the electrode lines).

[0232] In one embodiment, for example, the horizontal dimension of the building block in the first direction 191 (e.g., the x-direction) is at least 10 times the sum of the electrode line width and the electrode distance (also referred to as line gap). For example, the electrode distance can be taken as the sum of the maximum closest distances to the two nearest electrodes, such as the sum of distance 183 and distance 182. The electrode line width and the electrode distance depend on the application. As an example, the electrode line width can be taken as 5 microns. The electrode line width can be 1 micron, or 10 microns, or between the two, etc. Other values ​​are possible. For example, the vertical dimension of the building block in the second direction 192 (e.g., the y-direction) can adopt the same lower limit as the x-direction. For example, the building block is a rectangle or square with a side size of at least 500 microns, such as at least 1000 microns, etc.

[0233] In one embodiment, the electrode line width is not constant when measured along the electrode line. For example, the electrode line width can be measured orthogonal to the side of the electrode line. A constant electrode line width has the disadvantage that the line spacing also tends to be (more) constant, which in turn leads to diffraction. In practical designs, the width of the electrode is usually kept below a maximum value. As an example value, the maximum value can be taken as the maximum line spacing of the electrodes, so that the electrode line is nowhere thicker than the space between the electrodes.

[0234] The line gap (e.g. the distance between the electrodes) does not need to be constant. For example, in a spiral design (such as Figure 5b In spiral designs) it is possible to have a low diffraction design with a substantially constant line spacing, but in more random designs (such as Waal designs) the line spacing is typically not constant but is allowed to vary, for example within a range.

[0235] Making the building blocks too small may cause diffraction due to repetition of similar building blocks. Making the building blocks too large may cause optimization and evaluation problems in production. As an example, the sides of the building blocks may be 0.5 mm, 1 mm, 1 cm, and 10 cm, but may be up to, say, 100 cm or more. For example, one or both sides of the building blocks may be between 0.5 mm and 10 cm.

[0236] In one embodiment, the building blocks are square, but rectangles are possible. In one embodiment, the sides of the building blocks have the same ratio as the substrate. In one embodiment, the building blocks are not square, but can be one or more any plane filling shapes. For the diameter (e.g., the maximum distance between two points of the building block), the same lower limit as in the x-direction can be adopted.

[0237] The electrode pattern can be optimized for various constraints. For example, the length of the electrode is preferably short to maintain low resistance. In one embodiment, for a point on the substrate, the lengths of the two electrodes closest to the point are approximately equal, for example, with a ratio within a threshold of 1.

[0238] Of particular importance is the optical diffraction, which is preferably below a threshold. More information on diffraction for various embodiment designs is given herein.

[0239] Optical Diffraction

[0240] To estimate the optical diffraction, the following methods have been used:

[0241] 1. Prepare design pictures:

[0242] - Cropped to 1024x1024 microns (unit cell size);

[0243] - Normalize pixel values ​​to 255 (black = 0; white = 255);

[0244] 2. Use Bluestein's method [1, 2] to calculate amplitude & angle without scaling;

[0245] Since light diffraction can be formulated as a Fourier transform, the traditional method is to use the Fast Fourier Transform (FFT) algorithm. However, the use of FFT requires a fixed sampling relationship between the discretization of the input field and the discretization of the output field. The Bluestein method is efficient and flexible in selecting the sampling grid, and it uses the linear frequency z-transform (CZT) algorithm instead of the FFT algorithm.

[0246] 3. Find the zero-order (main) peak (I main )'s maximum strength;

[0247] 4. Ignore the amplitude spectrum with the main The pixel of the peak signal;

[0248] 5. In all other high-order peaks (I higher ) to find the maximum intensity,

[0249] 6. Calculate the resulting diffraction metric value, as in reference [3]:

[0250]

[0251] The experiments confirm that the calculated pixelation noise metric is consistent with the actual diffraction evident in the test setup.

[0252] A variety of designs have been used to test the noise metric parameters. Table 1 summarizes these tests. Informal design names are listed in column 1. Column 2 indicates the figure number for which the design is illustrated. Columns 7 and 8 present estimated intensity values ​​for the zero-order peak and higher-order peaks from the amplitude spectrum. Column 9 depicts the resulting pixelation metric values ​​(in %) for all designs. The lower the value, the better the diffraction level of the corresponding design.

[0253] Column 3 gives the longest length of the electrode in the building block. Columns 4 and 5 give the width (x-direction) and height (y-direction) of the building block. Column 6 gives the ratio of the longest electrode length to the diameter length in the building block.

[0254] The references cited above are as follows. They are incorporated by reference.

[0255] Leutenegger,M.,Rao,R.,Leitgeb,RA&Lasser,T.Fast focusfieldcalculations.Opt.Express 14,11277–11291(2006)

[0256] Efficient full-path optical calculation of scalarandvector diffraction using the Bluestein method.Light Sci.Appl.9,1–11(2020) by Hu,Y. et al.

[0257] Numerical comparison of grid patterndiffraction effects through measurement and modeling with OptiScansoftware.Proc.SPIE 8016,Window and DomeTechnologies andMaterials XII,80160U(2011)

[0258] Therefore, the pixelation noise metric can be calculated as follows:

[0259] First, a black and white design image is generated to a specific size, where the electrode lines are black and the substrate background is white. Conventional 8-bit bytes are used here to calculate the result to represent a pixel. In this case, 255 is used to represent white and 0 is used to represent black. The amplitude and angle of the linear frequency chirp z transform (CZT) are then calculated without scaling using the Bluestein method. The Bluestein method is a Fourier-type transform but gives computational properties. Finally, the pixelation noise metric can be calculated as the ratio between the higher peak and the main peak. The main peak is determined as the maximum intensity in the linear frequency chirp z transform (CZT) amplitude spectrum of the design image, and the higher peak is determined as the second maximum intensity within the linear frequency chirp z transform (CZT) amplitude spectrum excluding the main peak.

[0260] Table 1

[0261]

[0262]

[0263] Figures 4a to 4i An embodiment of a substrate having a low ratio is schematically shown. Figure 5a and Figure 5b An example of an embodiment of a substrate with a high ratio is schematically shown. Note that the high ratio design has low diffraction. The ratio is calculated as the quotient of the longest length and the length of the diagonal of a rectangle with the dimensions indicated in columns 4 and 5. Column 9 is calculated as the quotient of columns 8 and 7. Columns 3, 4, and 5 are in micrometers.

[0264] In the past, using experimental designs, it was shown that it was difficult to obtain a low pixelation noise metric. However, using a design according to one embodiment, it has been shown that a lower pixelation noise metric can be obtained.

[0265] In one embodiment, the ratio is at least 2, at least 3, at least 5, or at least 10. In one embodiment, the pixelation noise metric is below 6.10, below 6.07, below 6.05, below 6, below 5, or below 4. In one embodiment, the ratio is at least 2 and the pixelation noise metric is below 6.07. In one embodiment, the ratio is at least 3 and the pixelation noise metric is below 6.07. In one embodiment, the ratio is at least 10 and the pixelation noise metric is below 4. Designs with high ratios can be generated quickly and therefore can be easily tested and selected for any other requirements.

[0266] Figure 5a and Figure 5bA design with two drive electrodes on the surface of the substrate is shown. Either design can be modified to have only a single drive electrode on the surface of the substrate, for example, by removing one of the two drive electrodes. For example, such a modified design can be used in an optical modulator using a substrate with a single electrode.

[0267] Figures 4a to 4i and Figure 5a to Figure 5b The designs shown can be implemented in a single plane without having crossed electrodes. In particular, if these designs are connected to two drive buses, crossed electrodes are not required. When more than two drive electrodes are used, or if more complex electrode patterns are used, the crossing of electrodes can be used and can even become necessary. However, this crossing is possible, for example, at the position where two electrode lines cross, a dielectric material can be arranged between the electrodes. For example, this insulator can be deposited at the crossing position. For example, a first drive electrode is located in a first plane of the substrate, and a second drive electrode is located in a second plane of the substrate.

[0268] Figure 6a An example of an implementation of a building block 601 is schematically shown. Figure 1d An L-shaped drive bus for the substrate is shown, building block 601 is similar in this respect except that the drive bus is applied to the building block which is repeated across the substrate. This brings additional advantages.

[0269] Figure 6a Schematically, the configuration of the drive electrodes has been indicated in the interior of the building block 601. The two drive buses have been patterned to indicate that they drive different drive electrodes. Each of the two drive buses has two arms; the two arms extend along two sides of the building block, and the two sides meet at a corner of the building block. In this embodiment, the building block is square, although this is not required. One of the two arms extends along the entire length of the side, while the other is shortened to avoid electrical contact with the other drive bus. For example, the gap left between the two drive buses can have a size similar to the size between the drive electrodes, such as 50 microns. Note that the drive electrodes are partially connected by the drive bus. A portion of the drive electrode is connected to the drive bus in the x-direction, while the other portion is connected to one side in the y-direction.

[0270] The building blocks 601 so formed may be repeated in various ways across the substrate.

[0271] Figure 6b An example of an embodiment of a substrate 602 is schematically shown. Figure 6b middle, Figure 6aThe building blocks have been replicated multiple times. To obtain substrate 602, the building blocks are replicated by repeated translations in the x-direction and the y-direction. Figure 6b Each building block shown in can be obtained by direct translation of any other building block.

[0272] A disadvantage of this configuration is that the drive busses of different drive electrodes end up facing each other. To avoid short circuits, a small amount of space has been left, for example comparable to the width between the drive electrodes, for example 50 microns. Figure 6b Not shown, but the various parts of the translational drive bus need to be connected together, for example using electrode lines.

[0273] For example, indicated by arrow 640, vertical grooves are formed; that is, two electrode lines running parallel to each other. Similar grooves exist in the horizontal direction. It has been found that such grooves have an adverse effect on diffraction. If the building blocks have low diffraction, the design can still be better than a pattern using less good building blocks, but it is desirable to avoid these grooves.

[0274] Figure 6c An example of an embodiment of a substrate 603 is schematically shown. In substrate 603, the building blocks are repeated across the substrate, but the building blocks are arranged to avoid Figure 6b In this embodiment, the building blocks are translated and mirrored (in this case in two directions).

[0275] Building block 611 has been mirrored in the y direction to form building block 621. Building block 621 has been arranged directly at the bottom of building block 611. Building block 611 has been mirrored in the x direction to form building block 612. Building block 612 has been arranged directly to the right of building block 611. Building block 611 has been mirrored in both the x direction and the y direction to form building block 622. For example, the mirroring may have one side of the building block as the mirroring axis.

[0276] By mirroring the building blocks, we ensure that the drive buses for the same drive electrode terminate next to each other on the substrate. By merging these drive buses, we avoid trenches and reduce diffraction.

[0277] In one embodiment, at least the drive electrodes on the substrate have mirror symmetry; in one embodiment, the drive electrodes and the drive bus have mirror symmetry. For example, the substrate is symmetrical about the x-axis and / or about the y-axis. This is an important advantage in manufacturing because it allows the top and bottom substrates to be equal. There is no need to produce separate substrates for the top and bottom of the light modulator, nor is there a need to track separate types of substrates. In addition, the symmetry of the substrate allows a broken top substrate to be replaced by a bottom substrate, and vice versa - because they are identical. A straight line (such as a drive bus along an axis of mirror symmetry) is useful because the design can be mirrored around it. Using building blocks in mirrored and non-mirrored form helps to produce mirror symmetrical designs.

[0278] This is particularly advantageous when patterning the electrodes using a photolithography step, since the same substrate patterning can be used for both substrates of the light modulator, limiting production costs. The presence of straight busbars attached to the building blocks or to a portion of each building block contributes to this effect. In the absence of straight busbars, it is possible to have a symmetrical design in one direction to use the same electrode pattern for all substrates, for example by locally modifying the electrode design at the edges of the symmetry lines. In one embodiment, the drive electrode pattern has at least 1 symmetry in 1 direction, for example, using tiled building blocks with mirroring and / or rotation to achieve an electrode pattern design across the substrate.

[0279] Figure 6d An example of an embodiment of a substrate 604 is schematically shown. In substrate 604, building blocks are repeated across the substrate, but the building blocks are arranged to avoid Figure 6b In this embodiment, the building blocks are translated, mirrored, and rotated 180 degrees.

[0280] Building block 651 has been mirrored in the y direction to form building block 661. Building block 661 has been arranged directly at the bottom of building block 651. Building block 651 has been point reflected (e.g., rotated 180 degrees) to form building block 652. Building block 652 has been arranged directly to the right of building block 651. Building block 651 has been mirrored in the x direction to form building block 662.

[0281] Note that the odd columns of substrate 604 are identical to the odd columns of substrate 603. The even columns of substrate 604 are identical to the even columns of substrate 603 except that they are translated one building block in the y-direction.

[0282] By mirroring the building blocks, we ensure that the drive buses for the same drive electrode terminate next to each other on the substrate. By merging these drive buses, we avoid trenches and reduce diffraction.

[0283] Figure 6c and Figure 6dThe advantage of the pattern is that diffraction is reduced. Figure 6c The disadvantage of the pattern is that the connection point of one of the drive electrodes at the top and bottom of the substrate is much smaller than the connection point of the other electrode. This is not necessarily a problem because such electrical connections can be easily made, but this problem is Figure 6d has been avoided in Figure 6d The two electrodes can be easily connected, and this is true for both the top and bottom of substrate 604. Note that the drive bus at the far right of substrate 604 can be extended to the right at the top and / or bottom if desired.

[0284] get Figure 6d Another way to pattern the drive bus is to translate building block 651 one block to the right and invert its electrodes, e.g. a drive bus that previously drove the first electrode now drives the second electrode and vice versa. The next row starting at block 661 can be obtained by mirroring row 651. This shifted pattern will give the same pattern for the drive bus, but will be different when applied to the main line. When the pattern of the main line is inverted instead of dot-reflected, it may look very different.

[0285] Note, however, that the pattern of the drive electrodes can follow the same mirrored and translated pattern as the drive bus, but this is not required. The drive electrodes can follow a different pattern, such as Figure 6b This means that the driver bus might look like, for example Figure 6c or Figure 6d , but the main lines are the same between the blocks.

[0286] One advantage of the drive bus extending across the substrate is that the length from the drive electrode to a point on the substrate is shorter and more uniform, i.e., the difference between the length of the first electrode near a point and the length of the second electrode near a point is smaller.

[0287] A drive bus is not required. One or more or all drive electrodes on the substrate may be provided with power from another source rather than a drive bus applied on the same side of the substrate. For example, the drive electrode may be connected from one surface of the substrate (e.g., the inner surface) to a second surface of the substrate (e.g., the outer surface) through a through hole. The through hole may be connected to a power source at the outer surface, for example, the same power source or a similar power source may be used for the drive bus. For example, a drive bus may be applied on the outer surface from the edge of the substrate to the through hole; other configurations are possible. The connection to the power source may be through a controller.

[0288] For example, the drive electrode can be isolated from the edge of the substrate; for example, the isolated drive electrode can be surrounded by other drive electrodes from all sides. Using isolated electrodes greatly simplifies the design of the pattern because it is no longer necessary to ensure that each drive electrode can reach the drive bus. For example, the isolated drive electrode can be connected from the inside to the outside using a through hole; the through hole can be connected to a controller.

[0289] The through hole can also be used to connect one part of the drive electrode to another part of the same drive electrode. For example, the drive electrode can include two parts that are isolated from each other, for example, they can be isolated from each other due to another drive electrode running between them. Connecting two parts on the inner surface may cause an electrical short circuit. In one embodiment, the two parts or multiple parts are each connected by a through hole from the inside to the outside. At the outside, the through holes are electrically connected to each other; thus, the drive electrode is formed by its parts.

[0290] Back to Figure 5a . Such electrode designs can be constructed from subdivision surfaces. A particularly useful source of electrode designs are Delaunay triangulations and their corresponding Voronoiduals. These triangulations are a simple way to quickly generate a large number of subdivision surfaces, for example, to optimize the design. But other plane fillings may be used instead, for example, randomizations of regular tilings, or even non-periodic tilings such as Penrose tilings.

[0291] We refer to Yonghe, L. et al. (2013), “A Simple Sweep-line Delaunay Triangulation Algorithm”, Journal of Algorithms and Optimization (JAO) 1.1, pp. 30–38. This paper is incorporated by reference.

[0292] For example, the following algorithm may be followed. This embodiment is described for covering a substrate, but it may also be used for covering building blocks only.

[0293] I: Generates point distribution semi-randomly in a specific area.

[0294] Obtain a first set of points covering the substrate. For example, to obtain a semi-random distribution of points across the substrate, the following operation may be performed.

[0295] Step 1 - Initially distribute all points equally spaced in the region.

[0296] Step 2 - Then for each point, create a small random variable of the x,y coordinates. For example, you can take a random variable between equally spaced sets of points whose range is no greater than 30% of the initial distance between the points. Another way to get this kind of pattern is to draw points from a suitable distribution.

[0297] II: Computing the First and Second Networks

[0298] Step 3 - Compute triangulation. For example, the points can be triangulated where each point is connected to 6 neighboring points: except possibly on the edges and corners of the substrate. Delaunay triangulation has been found to perform well in this step. Delaunay triangulation is an example of a tiling.

[0299] Then the Voronoi pattern or Voronoi-like pattern is calculated based on the triangulation, for example as follows:

[0300] Step 4 – Create a second set of points corresponding to the center of the triangle.

[0301] Step 5 - Optionally, for each triangle center point, create a small random variable of the x,y coordinates. For example, the random variable can be similar to the first set of points, e.g., the variable is no larger than 30% of the initial distance between the points.

[0302] Step 6 - Connect the second set of points together across the boundary of the triangle; for example, compute the dual graph of the triangulation. For example, connect the center point to its immediate neighbors.

[0303] If the tiling used is a Delaunay triangulation, and the optional shifting of the second set of points is skipped, the second network thus obtained is a Voronoi network. If a different type of tiling or triangulation is used, or if the center points are shifted, the resulting polygonal grid will not be exactly a Voronoi network; although it will resemble such a network and be suitable for use in an optical modulator.

[0304] III: Creating the First and Second Electrode Patterns

[0305] At this point two networks have been created: the second network (Voronoi-like polygonal pattern) and the first network (eg Delaunay triangulation). Depending on the randomization, the two patterns are duals of each other, or nearly so.

[0306] From the second network (eg a Voronoi network) the pattern of the second electrode can be obtained by breaking selected edges (eg walls of a Voronoi polygon).From the first network (eg a triangulation) the pattern of the first electrode can be obtained.

[0307] Step 7 - Remove edges from the second network (e.g., a Voronoi-like network) until the network is simplified to a tree. This can be done by performing a path finding search algorithm on the first network (e.g., a triangulation) starting from a point in the first set of points (e.g., the center of a Voronoi polygon). The path finding algorithm attempts to find a path to each node of the first network. This algorithm is also known as finding a spanning tree in a graph.

[0308] Such a search algorithm can be a depth first search or a breadth first search. Breadth first search provides long but fairly straight patterns, while depth first search provides short and not straight patterns. The best results can be obtained by following a hybrid between a "depth first search" algorithm and a "breadth first search" algorithm. For example, the depth first search step or the breadth first search step can be selected by a probability distribution, for example depending on the depth of the search. A suitable distribution is the gamma distribution.

[0309] When an edge in the first network is included in the spanning tree, the dual edge in the second network that crosses the edge added in the first network is removed. Thus, the resulting spanning tree of the first network can produce a tree or forest in the second network, such as a Voronoi network. If the second network does not completely reduce to a tree or forest, this can be done by removing the extra edges in the second network.

[0310] In this way two trees are created which cover the substrate and intersect each other as required by the light modulator. Figure 5a The pattern is obtained using the above algorithm.

[0311] Once a suitable map is obtained, it can be converted into an actual electrode design by assigning a thickness to each path segment. As an example, a thickness of 10 microns can be used. For example, a mask layout tool can be used.

[0312] Further adjustments that can be made to the design include:

[0313] - Screen the design cells to eliminate shortcuts between electrode 1 and electrode 2. Shortcuts may have been introduced due to the increased thickness. These can be avoided by repeating the process, moving edges or moving nodes and repeating the generation process.

[0314] - Ability to add driver buses.

[0315] - Make the second electrode unified. What may happen is that the second electrode is a forest instead of a tree. This can be fixed by adding edges, usually by connecting to the driver bus, thus unifying the forest back into a tree.

[0316] - Correct the coordinates of points in the electrodes to maintain a minimum line gap between electrodes, say 20 um, and / or to maintain an average line gap between electrodes, say 50 um.

[0317] - Shifting the electrodes to allow stitching of the design and ensure continuity of the electrodes from 1 unit to another, especially if an overlay drive bus is not used.

[0318] - Displacing electrodes to reduce light diffraction, refraction, scattering or moiré.

[0319] - Improve or optimize randomization of short segment orientation to reduce light diffraction, refraction, scattering and moiré. This enables low disturbance when viewing through the display screen.

[0320] - Further randomization can be achieved by converting straight segments between points into curved shape segments. For example, splines can be used between the points.

[0321] It is found that further optimization of the design can be advantageously achieved in multiple optimization loops. For example, after generating the first electrode segment and the second electrode segment, such as using the above-mentioned process based on subdivision surfaces or the process based on Turing patterns, the segments can be converted into paths that are given widths. For example, the segments can represent the center lines of polygons with a specific width. This process will work most of the time, but may produce unwanted effects, so further optimization is possible.

[0322] For embodiment (A), it can be verified that the first path does not touch the second path. If this condition is violated, one or both of the paths (say the first path) can be modified so that the first path no longer touches the second path.

[0323] For embodiment (B), it may be verified that all first paths are connected in a single first electrode. If the condition is violated, the paths may be created and / or deleted to connect all first paths in the first electrode.

[0324] For embodiment (C), it may be verified that all second paths are connected in a single second electrode. If the condition is violated, the paths may be created and / or deleted to connect all first paths in the first electrode.

[0325] Parts B and C can be repeated in a loop until both electrodes are fully connected. Note that adding a drive bus to the design, such as described herein, can help unify the electrodes. Part A can also be repeated in this loop if desired.

[0326] Once the first electrode and the second electrode are fully connected and not short-circuited, the next loop of optimization can be performed.

[0327] For embodiment (D), it can be verified that the distance between the first electrode and the second electrode is always within a predetermined range. If this condition is violated, the path of the first and / or second electrode can be modified to keep the distance within the range.

[0328] You can repeat part D until you can find no point where the electrodes are too close or too far apart.

[0329] These optimizations can be accomplished by computer-implemented methods that optimize electrode patterns. Additional or alternative optimizations as suggested herein (e.g., above) can be added. For example, the design can be iterated for optical performance, length ratios, etc. Due to the low cost of generating the initial pattern of the first path and the second path (e.g., using subdivision surfaces or the like), the optimization process has the option of terminating the optimization and starting from a new pattern when not making enough progress. In one embodiment, the path itself will not be modified, but the first set of points and the second set of points will be modified, and the generation will be repeated from this point forward.

[0330] The electrodes obtained by this process have a large number of branching nodes and generally have many different angles. These factors are conducive to low diffraction. For example, a favorable substrate for an optical modulator includes a plurality of interdigitated drive electrodes applied to the substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate, wherein at least one of the first drive electrode and the second drive electrode is a spanning tree of a subdivision surface.

[0331] A computer-implemented method for obtaining a first electrode design and a second electrode design in a substrate for an optical modulator, wherein both the first electrode and the second electrode cover the substrate to achieve a configurable electric field in the optical modulator, the method comprising:

[0332] - obtaining a subdivision surface (100) of the substrate, the subdivision surface comprising a plurality of units (101; 102; 103) covering the substrate without overlapping;

[0333] - obtaining the center point (111) of each cell of the subdivision surface;

[0334] -Calculate the spanning tree on the center point ( Figure 1c ), where an edge in the spanning tree represents two adjacent cells of the subdivision surface,

[0335] - deriving a first electrode design (121) from the spanning tree,

[0336] - deriving a second electrode design (122) from the subdivision surface, said deriving comprising removing portions of the subdivision surface in which edges of the spanning tree intersect boundaries of cells of the subdivision surface.

[0337] Several variant embodiments are envisioned. For example, in the above embodiment, any one of the following variants may be added.

[0338] 1. Subdivision Surface

[0339] a. where the subdivision surface is non-periodic and / or random,

[0340] b. where the subdivision surface is a Voronoi diagram and / or a perturbed Voronoi diagram,

[0341] c. Wherein an initial set of random points covering the substrate is selected, the triangulation of this set of points is calculated, and a subdivision surface is obtained as the dual of the triangulation.

[0342] i. The triangulation can be Delaunay triangulation,

[0343] ii. the set of points can be obtained by perturbing a uniform set of points drawn from a distribution (e.g. a Poisson distribution),

[0344] iii. The dual can be calculated from a selected point in the triangle (eg the center of the circumcircle).

[0345] d. The maximum diameter of each unit is less than a threshold, such as 50 um.

[0346] 2. Spanning Tree

[0347] a. Spanning tree computation A spanning tree is iteratively constructed by selecting a cell from the subdivision surface that has been visited by a partial spanning tree but has unvisited neighbors, and extending the spanning tree by visiting one of the unvisited neighbors.

[0348] i. The selection of the visited unit can be a combination of depth-first and breadth-first, such as gamma distribution.

[0349] 3. Calibrate the electrode

[0350] a. Unified electrode

[0351] i. Identify components and join them together

[0352] 1. For example, by connecting sub-planes, or by assigning a separate sub-plane to each electrode and connecting in the sub-plane. Components can also be joined along the sides of the plane, either by tiling the design or by driving buses between building blocks.

[0353] 2. Select two adjacent components and connect them by reinserting the removed parts of the subdivision surface, removing the corresponding edges of the spanning tree, and / or vice versa.

[0354] b. Destroy the circular part of the second electrode

[0355] c. Adjusting the shortcut between the first electrode and the second electrode caused by imparting electrode width by moving portions of the first electrode and / or the second electrode.

[0356] d. Verify and adjust optical properties

[0357] i. The distance from any point in the plane to the first electrode and the second electrode should be lower than a threshold value (eg, 50 um), or their sum should be lower than a threshold value (50 um).

[0358] ii. The distance from the point on the first electrode to the second electrode should be at least the second threshold (20

[0359] um), and vice versa.

[0360] 4. Best modulator

[0361] a. A light modulator as in the general claim, wherein the first electrode design and the second electrode design are according to a design method as in any of the preceding claims.

[0362] It should be emphasized that the above method is not the only way to obtain a design with a low pixelation noise metric or with a high ratio of electrode length to diagonal. For example, instead of using a Voronoi network, a network based on Turing patterns can be used; see, for example, Alan Mathison Turing's paper "The chemical basis of morphogenesis", which is included herein by reference.

[0363] Figure 5b The design of is not obtained from subdivision surfaces, but still gives good values. For example, according to Figure 5b The design comprises a spiral. In the spiral, the first electrode line and the second electrode line belonging to the first drive electrode and the second drive electrode, respectively, are spiraled on the substrate. Even if in the areas between the spirals some of the electrical lines are more or less parallel, the pattern as a whole gives good values. The pattern can be improved even further by making the lines constituting the spiral fluctuate, in particular in the other turns, say turns 1-3 of the spiral. This fluctuation can be as follows Figure 4e or Figure 4f As shown, for example, by adding protrusions to the electrode lines of the interference pattern. For example, all the lines in the spiral can be wavy, where the amplitude of the ripples (eg, the amplitude of the protrusions) decreases towards the center of the spiral.

[0364] According to one embodiment, two substrates can be combined into a light modulator. The light modulator is particularly suitable for glass. The following is an exemplary embodiment of a light modulator.

[0365] Figure 7a An embodiment of a light modulator 10 applicable to smart glass is schematically shown.

[0366] Reference is made to patent application PCT / EP2020 / 052379, which is included herein by reference; this application comprises advantageous designs of light modulators, which are further improved, for example, by including electrodes, building blocks and / or substrates as explained herein.

[0367] The optical modulator 10 is capable of bidirectional electronic switching between a transparent state and a non-transparent state, or bidirectional electronic switching between a reflective state and a non-reflective state. The optical modulator 10 includes a first substrate 11 and a second substrate 12 arranged opposite to each other. At least two electrodes are applied on the inner side of the first substrate 11: shown as electrodes 13a, 13b. These at least two electrodes are collectively referred to as electrodes 13. At least two electrodes are applied on the inner side of the second substrate 12: shown as electrodes 14a, 14b. These at least two electrodes are collectively referred to as electrodes 14.

[0368] A fluid 15 is disposed between the substrates. The fluid includes particles 30 (e.g., nanoparticles and / or microparticles), wherein the particles are charged or can be charged. For example, the surface of the particles can inherently carry a charge. For example, the particles can be surrounded by charged molecules.

[0369] The electrodes are arranged to drive the particles 30 to move towards or away from the electrodes, depending on the applied electric field. The optical properties, in particular the transparency or reflectivity of the light modulator, depend on the position of the particles 30 in the fluid. For example, connections for applying an electromagnetic field to the electrodes may be provided.

[0370] At least one, but preferably two electrodes 13 and 14 are according to one embodiment, although they are only schematically shown in the figure.

[0371] In one embodiment, at least one of the electrode pattern on the first substrate and the electrode pattern on the second substrate has a low calculated pixelation noise metric, which contributes to diffraction. Interestingly, the electrode patterns on the substrates may not individually meet the limits on their pixelation noise metrics, but their combination, i.e., their superposition, may. Since this is the pattern that is visible when viewed through the light modulator, a low pixel noise metric in the superposition will also contribute to low diffraction. Suitable limits for the patterns on the first substrate and / or the second substrate or for the superposition include: less than 6.05%, or 5%, or 4%.

[0372] In one embodiment, substrates 11 and 12 are optically transparent outside the electrodes, typically with a transparency of >95% for the relevant wavelengths, such as a transparency of >99%. If the electrodes are taken into account, the transparency can be much lower, for example, 70%. The term "optical" can refer to wavelengths visible to the human eye (about 380nm to about 750nm), and can refer to a wider range of wavelengths, including infrared (about 750nm to 1μm) and ultraviolet (about 10nm to 380nm) wavelength ranges, if applicable, and sub-selections of the above wavelength ranges. In an exemplary embodiment of the light modulator, the substrate material is selected from glass and polymers.

[0373] In another embodiment, the substrates, such as the bottom substrate 12, can be reflective or partially reflective, while the top substrate 11 is transparent. The optical properties, in particular the reflectivity of the light modulator, depend on the position of the particles 30 in the fluid. When the panel is in the open state (vertically driven), the particles are mostly located between the opposing electrodes of the two substrates, so that the incident light can pass through the transparent top substrate and the optical layer relatively unimpeded, and is reflected or partially reflected on the bottom substrate.

[0374] The distance between the first substrate and the second substrate is typically less than 30 μm, such as 15 μm. In an exemplary embodiment of the light modulator, the distance between the first substrate and the second substrate is less than 500 μm, preferably less than 200 μm, preferably less than 100 μm, even more preferably less than 50 μm, such as less than 30 μm.

[0375] In one embodiment, the modulator may be provided in the form of a flexible polymer and the rest of the device may be provided in the form of glass. The glass may be rigid glass or flexible glass. If desired, a protective layer may be provided on the substrate. If more than one color is to be provided, more than one flexible polymer layer may be provided. The polymer may be polyethylene naphthalate (PEN), polyethylene terephthalate (PET) (optionally with a SiN layer), polyethylene (PE), etc. In another embodiment, the device may be provided in the form of at least one flexible polymer. Thus, the modulator may be attached to any surface, for example by using an adhesive.

[0376] The particles 30 may be adapted to absorb light, thereby preventing certain wavelengths of light from passing through. The particles 30 may reflect light; for example, the reflection may be specular, diffuse, or somewhere between specular and diffuse. The particles may absorb certain wavelengths and reflect other wavelengths. The particles may also or alternatively emit light using, for example, phosphorescence, fluorescence, etc. Even fluids may emit light, the emissivity of which may be modulated by changing the position of the particles.

[0377] In an exemplary embodiment of the light modulator, the size of the nanoparticles is 20nm to 1000nm, preferably 20nm to 300nm, more preferably less than 200nm. In an exemplary embodiment of the light modulator, the nanoparticles / microparticles may include a pigment coating, and preferably include a core. In an exemplary embodiment of the light modulator, the material made of the particle coating is selected from a conductive material and a semiconductive material.

[0378] In an exemplary embodiment of the optical modulator, the particles are suitable for absorbing light with a wavelength of 10nm to 1mm, such as 400nm to 800nm, 700nm to 1μm, and 10nm to 400nm, and / or suitable for absorbing a portion of light (filter) in the wavelength range of 10nm to 1mm, and combinations of the above.

[0379] In an exemplary embodiment of the light modulator, the particles are charged or can be charged. For example, the charge on the particles can be 0.1e to 10e (5*10 -7 to 0.1C / m2).

[0380] In an exemplary embodiment of the light modulator, the amount of fluid present is 1 g / m2 to 1000 g / m2, preferably 2 g / m2 to 75 g / m2, more preferably 20 g / m2 to 50 g / m2, such as 30 g / m2 to 40 g / m2. A great advantage is that in the arrangement of the invention, less fluid can be used, and likewise less particles can be used.

[0381] In an exemplary embodiment of the light modulator, the particles are present in an amount of 0.01 g / m2 to 70 g / m2, preferably 0.02 g / m2 to 10 g / m2, such as 0.1 g / m2 to 3 g / m2.

[0382] In an exemplary embodiment of the light modulator, the particles have a color selected from cyan, magenta, and yellow, and selected from black and white, and selected from combinations of the foregoing colors.

[0383] In an exemplary embodiment of a light modulator, the fluid includes one or more of a surfactant, an emulsifier, a polar compound, and a compound capable of forming hydrogen bonds.

[0384] The fluid 15 may be a polar fluid with a dielectric constant less than 15. In an exemplary embodiment of the light modulator, the relative permittivity εr of the fluid is less than 100, preferably less than 10, such as less than 5. In an exemplary embodiment of the light modulator, the fluid 15 has a dynamic viscosity higher than 10 mPa.s.

[0385] The electrodes 13a, 13b and electrodes 14a, 14b are in fluid contact with the fluid. The fluid may be in contact with the electrodes directly or indirectly, for example, the fluid may be in contact with the second medium of the electrodes, such as through a porous layer. In one embodiment, the electrodes cover about 1% to 30% of the substrate surface. In one embodiment, the electrodes include a conductive material having a resistivity of less than 100 nΩm (for comparison, the commonly used ITO has 105 nΩm at 273K, which is similar to the conductivity of >1*10 at 20°C). 7 S / m). In one embodiment, the light modulator electrode comprises: copper, silver, gold, aluminum, graphene, titanium, indium, and combinations thereof, preferably copper. The electrode may be embedded in a polymer substrate in the form of microwires (e.g., copper microwires).

[0386] A connection for applying an electromagnetic field to an electrode, wherein the electromagnetic field applied to the electrode causes nanoparticles and microparticles to move from a first electrode to a second electrode, and from the second electrode to the first electrode. A connection for applying an electromagnetic field to an electrode can be provided. For example, in an exemplary embodiment of the optical modulator, the current is between -100 μA and +100 μA, preferably between -30 μA and +30 μA, and more preferably between -25 μA and +25 μA. For example, a power supply can be electrically connected to at least two electrodes. The power supply is suitable for providing waveform power. At least one of amplitude, frequency and phase is suitable for providing different states for the optical modulator. For example, various aspects of the power supply can be adjusted by a controller.

[0387] The light modulator 10 may comprise one or more segments, a segment being a single optically switchable entity, the size of which may vary.The volume enclosed by the substrate may be a segment, or at least a part of a segment.

[0388] The device may include a drive circuit that changes the appearance of a (single) segment by applying an electromagnetic field. Thus, the appearance of the light modulator or one or more parts thereof may also be changed. For example, the segment may have a diameter of at least 1 mm. 2 This allows stacking of the present design to achieve more colors; for example, for full-color applications, two or three modulator stacks can provide most or all colors, respectively.

[0389] Having one or more segments allows the light modulator to be controlled locally; this is advantageous for some applications, but is not required. For smart glass, the light modulator can be used with or without segments. For example, when applied to smart glass, transparency or reflectivity can be controlled locally, such as blocking sun spots without reducing the transparency or reflectivity of the entire window. The segments can be relatively large, such as having a diameter of at least 1 mm, or at least 1 cm, etc.

[0390] In an exemplary embodiment of the light modulator, the substrates (11, 12) are aligned, and / or the electrodes (13, 14) are aligned. For example, the electrodes 13a, 13b and the electrodes 14a, 14b can be aligned to face each other. In the aligned substrates, the electrodes on different substrates are connected to each other when viewed from a direction orthogonal to the substrates. When the light modulator is disassembled, both substrates are arranged with the electrodes facing upward, and then the electrode patterns are mirror images of each other.

[0391] Aligning the substrates can increase the maximum transparency or maximum reflectivity of the light modulator. On the other hand, when the selection criteria for the light modulator are more than the transparency range or the reflectivity range, two substrates that are not aligned or not fully aligned may be better. The light modulator can be stacked. For example, two stacked light modulators can be made of three substrates, wherein the middle substrate has electrodes on both of its surfaces. In an embodiment of the light modulator, optionally at least one substrate 11, 12 of the first light modulator is the same as the substrate 11, 12 of at least one second light modulator. For stacked modulators, alignment can also increase the maximum transparency or maximum reflectivity, but may be detrimental to other considerations (e.g., diffraction).

[0392] Figure 7b An example of an embodiment of a light modulator 40 is schematically shown. The light modulator 40 is similar to the light modulator 10, except that it includes a plurality of optical layers; in the example shown, two optical layers. There may also be more than two optical layers. Each optical layer is arranged between two substrates. The light modulator 40 may be viewed as a Figure 7a As shown in the figure, the optical modulator 40 includes three substrates: a first substrate 41, a second substrate 42, and a third substrate 43. There is an optical layer between the substrate 41 and the substrate 42, and there is an optical layer between the substrate 42 and the substrate 43. The optical layer can be similar to the optical layer in the optical modulator 10. The controller 46 is configured to control the current of the electrodes of the substrates. For example, in Figure 7b In the embodiment, the controller 46 can be electrically connected to at least 8 (4 times 2 equals 8) electrodes.

[0393] Interestingly, the particles in multiple optical layers can be different, so that multiple layers can be used to control more optical properties of the light modulator. For example, particles in different optical layers can absorb or reflect different wavelengths, for example, can have different colors. This enables the creation of different colors and / or different color intensities on the panel by the controller 46. For example, a four-substrate panel can have three optical layers with particles of different colors (e.g., cyan, yellow, and magenta). By controlling the transparency or reflectivity of different colors, a wide spectrum of colors can be created.

[0394] For example, in one embodiment, the substrate surface facing the other substrate may be provided with two or more patterns. For example, the outer substrates 41 and 43 may only receive electrodes on the inner side, while the inner substrate (e.g., substrate 42) may have electrodes on both sides.

[0395] The substrate 41 and the substrate 42 can be used together as an embodiment of a light modulator. Similarly, the substrate 42 and the substrate 43 can be used together as an embodiment of a light modulator.

[0396] Figure 7c An example of an embodiment of a car 20 with a smart glass window 21 is schematically shown. This is a particularly advantageous embodiment because during driving, the level of incident light can change frequently and rapidly. A benefit of using smart glass in a car is that by adjusting the transparency of the window, the light level can be kept at a constant level. In addition, the reduced diffraction effect improves safety because the reduced diffraction effect reduces the distraction of the driver. The car 20 may include a controller configured to control the transparency or reflectivity of the window 21.

[0397] Smart glass can also be used in other glass applications, especially where the amount of incident light varies, such as buildings, offices, houses, greenhouses, and skylights. Skylights are windows placed in the ceiling to allow sunlight to enter a room.

[0398] The light modulator may have two optical states, such as a transparent state and a non-transparent state, or a reflective state and a non-reflective state. The light modulator (such as the light modulator 10 or the light modulator 40) may be configured as:

[0399] - switching to a second optical state (e.g. a non-transparent state) or a non-reflective state by generating an alternating voltage on at least one of the first substrate and the second substrate, applying an alternating current between at least the first electrode and the second electrode on the first substrate and / or between the first electrode and the second electrode on the second substrate, and

[0400] -Switching to a first optical state (e.g., a transparent state) or a reflective state by generating an alternating voltage between the first substrate and the second substrate, applying an alternating current between a first electrode on the first substrate and a first electrode on the second substrate, and / or between a second electrode on the first substrate and a second electrode on the second substrate.

[0401] The electrode pattern on the first substrate is at least partially arranged in the same pattern as the second electrode on the second substrate. Typically, the electrodes are opposite to each other, but the patterns of the first electrode and the second electrode may also be shifted relative to each other.

[0402] A protective coating may be provided on at least a portion of an inner surface area of ​​at least one of the first substrate and the second substrate.

[0403] The drive signal applied to the drive electrode typically has a varying voltage. For example, the power supply may be operated at an AC frequency for switching to a transparent state or a non-transparent state. Such a signal may have a frequency between, say, 1 Hz and 1000 Hz. By continuously switching the polarity of oppositely charged electrodes on and / or between the first and second substrates, a balanced electrolysis current may be obtained.

[0404] Figure 8a to Figure 8b A side view of an embodiment of a light modulator in use is schematically shown. Applying an electric field to the electrodes on the substrate causes the particles to be subjected to electric force. Using this effect, the particles can be moved, thereby enabling the light modulator to produce different transparency or reflectivity states. The controller can control the electric field, for example, the amplitude, frequency and phase of the electric field. In one embodiment, the controller is connected to at least four electrodes: two for each substrate. However, more electrodes can be used and connected to the controller; for example, the substrate can use more than 2 electrodes to better fine-tune the grayscale and drive to a non-transparent state or a non-reflective state. Multiple electrodes can also be used to support multiple segments on the substrate.

[0405] Figure 8a is shown for the light modulator without an applied electric field. Figure 8a In the present invention, no electric force is applied to the particles 30 suspended in the fluid 15.

[0406] exist Figure 8a In the configuration shown, the conductive electrode pattern arranged on the top substrate is completely or substantially aligned with the conductive electrode pattern on the bottom substrate. The conductive electrode pattern can be deposited on a transparent or (partially) reflective glass substrate, or embedded in a plastic substrate, etc.

[0407] Alignment between the top electrode pattern and the bottom electrode pattern helps to expand the range of achievable transparency levels or reflectivity levels. However, alignment is not necessary, as similar effects can be achieved without alignment. In the case of non-alignment, a certain range of transparency or reflectivity can also be achieved.

[0408] Please note that in these embodiments, reference to the top substrate and bottom substrate refers to the substrate that is higher or lower on the page. The same substrates may also be referred to as, for example, the front substrate and the back substrate, because in glass applications, the substrates are arranged vertically rather than horizontally aligned.

[0409] Figure 8bA light modulator is shown in which, for example in example P1, a potential +V1 is applied to each micro-wire electrode on the top substrate, while a negative voltage, such as -V1, is applied to each micro-wire electrode on the bottom substrate. Thus, in this case, the same positive potential is applied to all electrodes 13, while the same negative potential is applied to electrode 14. The difference in potential causes negatively charged particles to flow to the vicinity of the electrode of the top substrate, where the particles will be substantially aligned with the top electrode. As a result, if both the top substrate and the bottom substrate are transparent, the transparency of the light modulator 10 is improved. Similarly, if, for example, the top substrate is transparent and the bottom substrate is reflective, the reflectivity of the light modulator 10 is improved. If the solution contains positively charged particles, they will flow to the vicinity of the electrode of the bottom substrate, where the particles will be substantially aligned with the bottom electrode.

[0410] In the second example P2, similar transparency or reflectivity can be achieved when the voltages of the top and bottom electrodes are opposite to those of the example P1. In example P2, the voltage of each electrode of the top substrate is now provided with a negative potential -V1, while the voltage of the aligned electrodes of the bottom substrate is provided with a positive potential. This state is similar to Figure 8b , but the top substrate is exchanged with the bottom substrate. Also in this configuration, the transparency or reflectivity of the light modulator 10 is also high.

[0411] Interestingly, by placing a top substrate electrode (e.g. Figure 8b The positive potential of electrode 13 (and the negative potential of electrode 14) shown in FIG. 1 is related to the bottom substrate electrode (e.g., Figure 8b By switching between the positive potential of the electrode 14 shown in FIG. 1 , transparency or reflectivity can be maintained while reducing corrosion damage to the electrode. This alternating electric field can be achieved by applying alternating potentials to the top electrode and the bottom electrode.

[0412] Applying a waveform is optional and is an effective measure to increase the life of the optical modulator by reducing corrosion. For example, when copper electrodes are used, corrosion may form because copper ions are dissolved in the ionic fluid of one substrate and flow to the electrode of the opposite substrate and deposit there. By applying a waveform, the direction of copper ion transport is frequently reversed, thereby reducing corrosion damage. Between the two instances P1 and P2, the corrosion current between the two substrates is balanced, or substantially balanced, such as >95% balanced, for example, with the corrosion rate of the electrode of the top plate occurring, and between each time instance, for example, in P1 or P2, there is a balanced copper deposition on the bottom electrode. Therefore, particles are continuously converted or migrated between the top electrode and the bottom electrode, and the optical modulator or smart window is always in the on state, and the dynamic electrolysis current between the top electrode and the bottom electrode is constant, so there is no net loss or a negligible net loss of electrode material on the top substrate and the bottom substrate.

[0413] Figure 8c It is shown how a reduced transparency state or a reduced reflectivity state can be obtained. Alternating voltages are applied to the same substrate. Figure 8c As shown, for example, in one embodiment, a potential +V2 is applied to the first electrode, and the next adjacent electrode has an opposite potential -V2, and so on. This can be achieved by applying a potential +V2 to electrode 13a and an opposite potential -V2 to electrode 13b. On the opposing substrate, a potential +V2 may be applied to electrode 14a, and an opposite potential -V2 may be applied to electrode 14b. For example, the electrodes may be arranged so that the electrodes on the substrates are aligned; an electrode on the top substrate has an opposite electrode on the bottom substrate, and vice versa. For example, to reduce transparency or reflectivity, opposing electrodes may receive the same potential, while adjacent electrodes receive opposite potentials. As Figure 8c An embodiment is shown in which four electrodes are indicated by reference numerals 13a, 13b, 14a and 14b, with the other electrodes continuing to alternate.

[0414] By using this AC drive cycle between the top and bottom substrates, a diagonal and lateral electric field is generated between the two substrates, which causes the particles to diffuse randomly, thereby establishing the closed state of the light modulator. As a result of this configuration, the particles migrate diagonally and laterally between the top and bottom substrates, and the diffusion of the particles into the visible aperture of the light modulator contributes to the closed, opaque state of the light modulator.

[0415] As for Figure 8b The transparent state shown, a waveform can be applied to the electrodes so that, for example Figure 8b The electrode with positive potential shown in the figure becomes negative potential, and the electrode with negative potential becomes positive potential. Figure 8b As shown, for example, applying a waveform between electrodes 13a and 13b and between electrodes 14a and 14b can reduce corrosion damage to the electrodes.

[0416] By using a combination of Figure 5, Figures 6a to 6d The AC drive cycle can be achieved by the staggered line configuration of the top electrode and bottom electrode configuration shown in the isoplanatic view.

[0417] Figure 8b and Figure 8cThe degree of increase or decrease in transparency or reflectivity depends on the voltage difference and the frequency difference. By changing the voltage difference, the amount of increase or decrease in transparency or reflectivity can be controlled. For example, a curve representing the change in transmittance relative to voltage can be determined (e.g., measured). In order to obtain a specific transmittance level (e.g., a specific transparency, a specific grayscale level), a corresponding voltage (e.g., an alternating voltage) can be applied. By interpolating the transparent state signal or the non-transparent state signal, a level between transparent and non-transparent can be obtained. Similarly, a curve representing the change in light reflection relative to voltage can be determined (e.g., measured). In order to obtain a specific reflectivity level, a corresponding voltage (e.g., an alternating voltage) can be applied. By interpolating the reflective state signal or the non-reflective state signal, a level between reflective and non-reflective can be obtained.

[0418] For the light modulator, different electrode patterns can be used. The electrode patterns can each provide a grayscale range (e.g., the transparency level or reflectivity level that the light modulator can achieve). However, the specific grayscale range of any particular electrode pattern may be different from other electrode patterns. In other words, although different patterns can give increased transparency or reflectivity or increased opacity, the exact response to the drive signal depends on many factors, including the specific pattern used. The change in the optical properties of the light modulator can have a high resolution (e.g., a resolution of less than 1 mm). It should be noted that different optical patterns (e.g., logos) visible in the light modulator can be achieved without the need for a pixelated light modulator.

[0419] This effect can be used to embed a visible image in a light modulator by locally changing the electrode pattern on the light modulator substrate. For example, due to the different electrode patterns, it is possible to have local grayscales with grayscales that are permanently offset relative to each other. For example, by locally changing the electrode pattern or its pitch, the maximum transparency or the maximum reflectivity can be changed.

[0420] The result is that regions on the light modulator have different grayscale intensities, e.g., different shades of gray, or colors. However, the regions may have the same color point. In one embodiment, the regions may switch together with the rest of the window, albeit at different rates. For example, even if the same voltage is applied to electrodes in two different regions, they may result in different transparent states (e.g., different levels of transmittance) due to the different electrode patterns. For example, a curve representing transmittance versus voltage change may be shifted. For example, if two regions change voltage control in the same way, the light transmittance of the two regions may change, but the amount of the change is different. A region may also be made less responsive to a drive signal by reducing the density of electrodes; in particular, a region may not switch at all, e.g., by not applying electrodes to the region.

[0421] For example, the electrode material can be copper, aluminum, gold, indium tin oxide (ITO), etc. ITO is transparent, while copper / aluminum is reflective, so using different electrode materials, different appearances can be obtained, regardless of the driving voltage. Similarly, different materials have different resistances and will induce different electric fields. For example, even if the same voltage is used to drive, ITO will have a smaller electric field.

[0422] One embodiment of the method of modulating light includes applying an electric potential to a plurality of drive electrodes applied to two opposing substrates to obtain an electromagnetic field between the plurality of drive electrodes to provide electrophoretic movement of particles to or from one of the plurality of drive electrodes, thereby causing modulation of light irradiated through the substrates, wherein the two opposing substrates are as in one embodiment.

[0423] There are many different ways to perform the method, which will be apparent to those skilled in the art. For example, the order of the steps can be performed in the order shown, but the order of the steps can also be changed, or certain steps can be performed in parallel. In addition, other method steps can be inserted between steps. As described herein, the inserted steps can represent improvements to the method, but can also be unrelated to the method. For example, certain steps can be performed at least partially in parallel. In addition, a given step may not be fully completed before the next step is started.

[0424] The electrodes may be driven using a signal having a selected maximum amplitude corresponding to one of a plurality of transparency levels or reflectivity levels of the light modulator. The signal may be an alternating current or an alternating voltage.

[0425] The embodiment of the method can be performed using software, and the software includes instructions for causing a processor system to perform the method. The software may include only those steps taken by a specific sub-entity of the system. The software may be stored in a suitable storage medium (such as a hard disk, a floppy disk, a memory, an optical disk, etc.). The software may be sent as a signal along a wired or wireless connection, or sent using a data network (e.g., the Internet). The software is available for download and / or for remote use from a server. The embodiment of the method may be performed using a bitstream, and the bitstream is arranged to configure a programmable logic, for example, a field programmable gate array (FPGA), to perform the method.

[0426] It is to be understood that the subject matter disclosed herein also extends to computer programs, particularly computer programs on or in a carrier, suitable for implementing the subject matter disclosed herein. The program may be in the form of source code, object code, code intermediate source, and the object code may be in the form of a partial compilation, or any other form suitable for implementing the embodiment of the embodiment of the method. An embodiment related to a computer program product includes computer executable instructions corresponding to each processing step of at least one method described. These instructions may be subdivided into subroutines and / or stored in one or more files, which may be linked statically or dynamically. Another embodiment related to a computer program product includes computer executable instructions corresponding to each device, unit and / or part of at least one system and / or product described herein.

[0427] Figure 9a A computer readable medium 1000 having a writable portion 1010 including a computer program 1020 is shown, and a computer readable medium 1001 also has a writable portion including a computer program. The computer program 1020 includes instructions for causing a processor system to perform a light modulator method according to one embodiment. For example, the processor system can be connected to a light modulator panel. The computer program 1020 can be embodied on the computer readable medium 1000 as a physical mark or through the magnetization of the computer readable medium 1000. However, any other suitable implementation is also conceivable. In addition, it is understood that although the computer readable medium 1000 is shown as an optical disk, the computer readable medium 1000 can be any suitable computer readable medium, such as a hard disk, a solid state memory, a flash memory, etc., and can be non-recordable or recordable. The computer program 1020 includes instructions for causing a processor system to perform the light modulator method.

[0428] Figure 9b In a schematic representation a processor system 1140 is shown according to an embodiment of an implementation of a controller of an optical modulator. The processor system comprises one or more integrated circuits 1110 . Figure 9bThe architecture of one or more integrated circuits 1110 is schematically shown. The circuit 1110 includes a processing unit 1120 (e.g., a CPU) for running a computer program component to execute a method according to an embodiment and / or a module or unit for executing an embodiment. The circuit 1110 includes a memory 1122 for storing programming codes, data, etc. A portion of the memory 1122 may be read-only. The circuit 1110 includes a communication element 1126 (e.g., an antenna, a connector, or both). The circuit 1110 may include a dedicated integrated circuit 1124, which is used to perform a part or all of the processing defined in the method. The processor 1120, the memory 1122, the dedicated IC 1124, and the communication element 1126 may be connected to each other via an internal connection 1130 (e.g., a bus). Using antennas and / or connectors, respectively, the processor system 1110 may be arranged for contact communication and / or for contactless communication.

[0429] For example, in one embodiment, the processor system 1140, for example, the device may include a processor circuit and a memory circuit, and the processor is arranged to execute software stored in the memory circuit. For example, the processor circuit may be an Intel Core i7 processor, an ARM Cortex-R8, etc. In one embodiment, the processor circuit may be an ARM Cortex M0. The memory circuit may be a ROM circuit, or a non-volatile memory (e.g., flash memory). The memory circuit may be a volatile memory (e.g., SRAM memory). In the latter case, the device may include a non-volatile software interface (e.g., a hard disk, a network interface, etc.) arranged to provide software.

[0430] A controller for an optical modulator, for example a controller for controlling the voltage applied to an electrode, may comprise a processor circuit, but may also or instead comprise a state machine.

[0431] Figures 10a to 10d Aspects of embodiments of light modulators are schematically shown. The modulators are exemplary and non-limiting. Figures 10a to 10d Corresponding to the same embodiment of the optical modulator. The modulator can be advantageously combined with other features described herein. The components of the modulator can be advantageous alone or in combination with other features described herein. In particular, Figures 10a to 10d Advantageous embodiments of building blocks, drive electrodes, drive buses, bus electrode connections, etc. are provided, each of which may be considered separately.

[0432] In the implementation of the building block, Fig.10aThe building block 820 in is an embodiment, which includes a pattern of multiple electrodes arranged in a forked pattern. When the building block is repeated across the substrate, the electrodes terminating on the left and right sides of the building block and the drive electrodes terminating on the upper and lower sides of the building block will match, thereby forming multiple drive electrodes, in this case for an optical modulator. The drive electrodes are arranged in a forked pattern. It may or may not be necessary to connect the electrodes at the ends of the repeated building blocks to join them into the drive electrodes. In the building block 820, the number of drive electrodes is two, for example, a first drive electrode and a second drive electrode. However, it is possible to have more than two drive electrodes.

[0433] The illustrated building block 820 has several advantageous properties that help reduce interference in an optical modulator incorporating the building block, as shown in FIGS. 10 b to 10 c. Fig.10d shown.

[0434] For example, the first property satisfied by building block 820 is that, for at least one electrode among the plurality of interdigitated electrodes in building block 820, the maximum length between any two points on the electrode measured along the electrode in building block 820 is at least 2 times the length of the diagonal of the building block. In fact, in this embodiment, this property applies to the plurality of electrodes of building block 820.

[0435] For example, the second property satisfied by building block 820 is that it includes electrodes branching at nodes, forming a tree. Building block 820 shows a highly branched tree, for example, there is a first node in which the electrode branches into at least three lines, each of which is connected to at least three second nodes, which also branch into at least three. In fact, there may even be three second nodes connected to a third node, where the electrode also branches.

[0436] For example, the third property that the electrodes in the building block satisfy is that the angles at the nodes of the electrodes are well distributed in the range of 0 to 360. For example, the building block shows at least some angles in the range of 0-30, some in the range of 30-60, and even in the range of 330-360. In fact, any range from x to x+30 is Fig.10a In fact, this property applies to multiple electrodes in building block 820.

[0437] In building block 820, the electrode line is composed of connected straight line segments. Line segments can also be curved, or vice versa. In this embodiment, the electrode line width in building block 820 is constant along the electrode line; this is not required.

[0438] For example, a fourth property satisfied by the building block is that it has a low computational pixelation noise metric; in this case below 4%.

[0439] Any of the above characteristics may be used to address interference without combining them as in building block 820. For example, there may be only characteristic 1, or only characteristic 2, or only characteristic 3, or only characteristic 4, or a combination of, say, 1 and 2, or 2 and 3, 2 and 4, 3 and 4, 1 and 2 and 3 and 4, 2 and 4 and 4, or any other combination that may be combined with other features described herein.

[0440] Building block 820 also satisfies that the distance between two adjacent lines is constrained, for example, above a minimum value and below a maximum value. Building block 820 is an embodiment of a building block in which electrodes are located in the same plane and do not cross. Note that this is not an obstacle if it is desired to cross electrodes. For example, two electrodes can cross by having a separator between them at the intersection. The separator can be the substrate itself, for example, one of the electrodes can turn via two through holes to travel on the back side of the substrate.

[0441] Figure 10b.1 A substrate 810 and a drive bus are schematically shown. A drive bus 812 and a drive bus 814 are shown. To create a substrate for an optical modulator, building block 820 is repeated within an area bounded by the drive bus. The drive bus is arranged to drive drive electrodes. In this embodiment, a first drive electrode 812 is arranged at two adjacent sides of the substrate, and a second drive electrode 814 is arranged at two opposite adjacent sides of the substrate. The electrodes 812 and 814 are not in contact. In use, a varying voltage is applied to the electrodes 812 and 814 to generate a voltage between the substrate 810 and an opposing substrate ( Figure 10b.1 A voltage distribution is generated between the electrodes (not shown), thereby causing an optical effect.

[0442] Specifically, the drive bus 812 or side electrode extends along the left side and the top side. At one point, a connection point is provided for connecting the bus 812 to the controller, shown here at the upper left. Specifically, the drive bus 814 or side electrode extends along the right side and the bottom side. At one point, a connection point is set for connecting the bus 814 to the controller. The bus 814 extends outside the bus 812 along the top side of the bus 812. The advantage of extending an electrode (such as bus 814) along three sides is that two electrodes can be connected from the same side. That is, the entire optical modulator can be powered from a single side of the substrate. The bus 814 extends a limited portion here, for example, less than a quarter of the side. The bus 814 may also extend further to a connection portion close to the bus 812.

[0443] The base plate formed in this way can be combined, for example, with a mirror image of the base plate, for example with a design flipped on a horizontal axis, or with a design flipped on a vertical axis.

[0444] Figure 10b.2 A variation of a substrate 810 and a drive bus is schematically shown. A drive bus 812 and a drive bus 814 are shown. Figure 10b.1 Similarly, building block 820 is repeated within the area bounded by drive buses 812 and 814 .

[0445] In addition to the drive busses along the edge of substrate 810, additional drive busses are shown extending into the interior of substrate 810 and across it.

[0446] Figure 10b.2 Additional drive buses 815-819 are shown running across the substrate. Some additional drive buses (buses 815 and 816 in this embodiment) are connected to drive bus 814. Some additional drive buses (buses 817 and 819 in this embodiment) are connected to drive bus 812. Extending from the additional drive buses are optional protrusions running along one side of a copy of the building block. In this way, each building block can have a drive bus running along each of its edges, for example, a first drive bus for two sides connected at the vertices of the building block, and a second drive bus for the other two sides connected at diagonally opposite vertices. Figure 10b.2 The base plate can also be combined with a mirror image.

[0447] Figure 10b.2 The advantage of the arrangement shown in is that the power is more evenly distributed across the device. Therefore, the transition is more uniform and is completed faster.

[0448] Although Figure 10b.1 and 10b.2 The building blocks shown in FIG. 1 have square building blocks, but in general, the building blocks may have any shape. In particular, any shape or shapes of the tiling plane may be used, such as a repeatable shape. In particular, it may have a rectangular shape, such as a non-square shape. For example, one side may be at least 1.5 times longer than the other side. The shape of the building block may be the same as the shape of the optical modulator, such as having the same relative dimensions.

[0449] One or more building block stepper masks may be used to pattern the building blocks. Additional steppers may be used for the drive bus. Steppers may also be used if the connection is made by overlapping metal deposition. For example, when a stepper is processing the metal of the drive bus 812, it may overlap where 820 is located. Connections from the outside to the electrodes (e.g., to 812) may use conventional foil thickening or fixtures.

[0450] Also note that 1 type of building block can be repeated, but multiple types of building blocks can also be used. For example, the shape can be triangular. The shape of the building block can affect the shape of the entire device. This is useful, for example, to adjust the form factor of the optical modulator. It is even possible to combine building blocks of different shapes in a single substrate. For example, you can have a square or rectangular shape in the center of the substrate and a triangular shape at the edges.

[0451] For substrates without straight edges, it is useful to use different shapes and / or sizes, as discussed further herein. For curved substrates (e.g., non-flat substrates), it is also useful to use different shapes and / or sizes. Although this is not absolutely necessary, using different shapes for building blocks allows the building blocks to better follow the shape of the substrate. A curved substrate can be combined with another curved substrate to form a curved optical modulator. For example, in one embodiment, the drive bus is arranged along a triangulation of the curved substrate, the drive bus follows the triangulation and the building block shape is arranged between them. For example, in one embodiment, the building blocks around the center of the substrate are square or rectangular, but the building blocks at the edge are triangles. The latter configuration can be accomplished using two or more shapes. Note that a curved substrate can be supported by a building block of a single shape, but it is advantageous to use multiple shapes. In general, building blocks of different shapes can also be applied in curved substrates without long electrodes. One embodiment of such a substrate is a substrate for an optical modulator, the substrate comprising a plurality of interdigitated drive electrodes applied to the substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate, the pattern of the plurality of drive electrodes across the substrate comprising a plurality of repeating building blocks, the building blocks comprising a plurality of interdigitated electrodes extending in at least 2 directions across the building blocks, the interdigitated electrodes in the building blocks forming drive electrodes, wherein the substrate is curved, and the plurality of repeating building blocks comprise at least two different shapes.

[0452] Fig.10c Schematically shows Fig.10d Details of a corner, as discussed below. Fig.10c A corner of building block 820 is shown, along with portions of drive bus 812 and drive bus 814. Figure 10d to Figure 10d Building blocks 820 are schematically shown repeated across a substrate. Fig.10d Corresponds to Figure 8b . Fig.10d Corresponds to Figure 8b The building block 820 is repeated across the substrate in both directions by translation. The repetition may be a sliding translation, such as a translation followed by a reflection.

[0453] Fig.10cIt shows how electrodes formed by the repetition of building blocks are connected to the drive bus. For example, electrode lines can extend from the drive bus to electrodes in the building blocks.

[0454] Fig.10d Details of the repetition of building blocks 820 between buses 812 and 814 are schematically shown. Fig.10d Portions of four copies of this building block are shown in . The edges between building blocks are indicated with capital letters A, B, C, and D. Note that the electrode on one side of the building block connects to the electrode on the opposite side of the electrode; in this case, the electrodes in the design match so that aligning the building blocks is sufficient to create a continuous electrode.

[0455] In this embodiment, drawing Fig.10a so that the blocks overlap slightly when repeated across the substrate, e.g. Fig.10d . If desired, it is possible to avoid having overlap, but it is convenient. The overlap in this embodiment is 3%. That is, 3% of the size of a building block in the x direction overlaps with 3% of the size of the next block in the x direction. The amount of overlap is preferably small, say between 1% and 5%. Larger or smaller overlaps are possible. It is also possible to have no overlap at all, in which case the building blocks will be aligned directly next to each other. The same applies to the y direction, for example, 3% overlap, overlap between 1% and 5%, etc. are possible embodiments.

[0456] In this embodiment, building block 820 is repeated across the substrate in two orthogonal directions by translation. The repetition may be a sliding translation, such as a translation followed by reflection.

[0457] Fig.11 A cross section of an embodiment of a light modulator 700 is schematically shown. Fig.11 Two substrates are shown: substrate 772 and substrate 774. For example, according to one embodiment, interdigitated drive electrodes and drive buses are applied to their surfaces. Spacers 750 are arranged between substrates 772 and 774 to keep the substrates at a predetermined distance. The space between the two substrates is filled with semiconductor ink 760, for example as described herein, and edge seals are applied around the edges of the two substrates. By selecting different types of inks, the panel can be configured to modulate between, for example, transparent to opaque or reflective and non-reflective, etc.

[0458] Fig.12a One embodiment of a light modulator is schematically shown. Fig.12a, a corner of a substrate according to one embodiment is shown. The drive bus or edge connector is arranged along the upper edge and right edge of the substrate. The drive electrodes corresponding to the drive bus are connected to its drive bus at multiple points, such as a first point and a second point. For some parts of the electrode, two connections may be required to unify the electrode, for example, to ensure that the entire electrode is connected. However, it can be arranged to connect the electrode to the drive bus multiple times, even when the first electrode does not need to be connected. For example, the first point and the second point can be connected along the drive bus, but can also be connected across the substrate through the electrode. In that case, a portion of the drive bus between the first point and the second point can be removed. Removing this portion of the drive bus does not disconnect the drive bus from the power supply because the drive bus remains connected through the electrode. Figure 12b An embodiment is shown in which a portion of the drive bus has been removed. Fig.12c The same portion of the substrate is shown, but with the electrodes connecting portions 902, 904 and 906 highlighted.

[0459] Breaking up long electrode traces, especially straight traces, helps reduce diffraction. If edge connectors are only located at the edge of the device, e.g. Figures 10a to 10d In the embodiment shown in FIG. 1 , this will only make a small difference. But for the embodiment where the drive bus surrounds the building blocks, the impact is obvious. The straight lines around the building blocks will significantly increase diffraction and optical artifacts. Here these straight lines can be appropriately interrupted and thus reduce diffraction or optical artifacts. For example, such as Figures 6a to 6d The drive bus shown may benefit from removing a portion of the drive bus.

[0460] Fig.13a Examples of implementations of building blocks are schematically shown. Fig.13b An example of an embodiment of a substrate for a light modulator is schematically shown. Fig.13a The building blocks have been spanned in both directions Fig.13b of the substrate is repeated, in this case parallel to the edge of the substrate. Fig.13a The interdigitated electrodes in the building blocks of Fig.13b The two interdigitated drive electrodes are connected to form two interdigitated drive electrodes that extend across the building block in at least 2 directions.

[0461] Note that Figure 13 and Fig.13b The electrodes shown in are highly coiled. This can be seen, for example, from their high degree of branching or from the high ratio between the maximum length between any two points on the electrode in the building block and the diagonal of the building block (the ratio is higher than 2).

[0462] Fig.13bThe drive electrodes in the substrate of the 3D model are in the same plane and do not cross. Note that this design has fully connected electrodes and no floating electrodes on the edges. Note that some electrodes on the edges of the building blocks are connected through electrodes in adjacent building blocks.

[0463] The building block is based on so-called Turing patterns. Turing patterns have proven to be advantageous because they produce fewer but longer branches. Therefore, there is a lower probability of designing floating electrodes that may have to be processed separately. Turing patterns are also called reaction-diffusion systems, and in this particular embodiment, the Gray-Scott equations are used.

[0464] Figure 14a to Figure 14h An embodiment of a substrate is schematically shown in which a pattern of multiple drive electrodes across the substrate includes multiple repeating building blocks. The repeating building blocks form multiple interdigitated electrodes extending in at least 2 directions across the substrate. The electrodes in the building blocks can have various advantageous properties, for example, having a high ratio between electrode length and diagonal; but this is not required. One type of building block can be used, or multiple types of building blocks can be used. The blocks can be rotated, mirrored and / or translated to fill the substrate. In order to distribute power, a drive bus can be arranged between the building blocks; alternatively or additionally, the building blocks can be interconnected to distribute power. The building blocks can have the same shape, but their electrode patterns can still be different or not.

[0465] Fig.14a An embodiment of the substrate is schematically shown, wherein the building blocks are rectangular, in this case square.

[0466] Fig.14b and Fig.14c An embodiment of the substrate is schematically shown in which the building blocks are triangular, in this case right triangles. Any other triangular shape is also possible.

[0467] The advantage of having building blocks of different shapes is that substrates of different shapes can be supported more easily. For example, a square-shaped substrate can be supported by a square building block, or by a triangular building block, as shown in Figures 14 and Fig.14b However, using triangular building blocks, triangular substrates can be easily tiled, for example without the need to support partial building blocks or different types of building blocks at the edges.

[0468] Fig.14d An embodiment of the substrate is schematically shown, wherein the building blocks are hexagons, in this case regular hexagons.

[0469] Fig.14e An embodiment of a substrate is schematically shown wherein the building blocks are trapezoidal.

[0470] Fig.14f An embodiment of the substrate is schematically shown in which the building blocks are polygons, in this case rectangular polygons, e.g., with right angles. Note that the polygons need not be convex, e.g. Fig.14f As shown. The polygon can be a polyomino; for example, a polygon constructed from an integer number of squares. In the embodiment shown, three dominoes are used. Other embodiments of polyominos include four dominoes and five dominoes. The polygon can be an equilateral polygon, such as a rectilinear polygon.

[0471] Figure 14g An embodiment of a substrate is schematically shown, wherein the building blocks are square. Figure 14h An embodiment of a substrate is schematically shown, where the building blocks are triangular. Note that various shapes of substrates can be supported by combining building blocks. Note also that with triangular building blocks, different shapes for the substrate are possible.

[0472] Figure 14h The shape of the substrate in can also be supported by rectangular building blocks, although partial building blocks or edge-type building blocks may be used to support the slanted edges of the substrate, etc.

[0473] Different shapes of support substrates are beneficial for supporting different applications. For example, in cars, windows are usually not rectangular. Building blocks with different shapes can more easily support the desired shape.

[0474] Different shapes of support substrates can also be useful for supporting non-planar substrates.

[0475] The numbered items below are intended implementations.

[0476] Item 1. A substrate for an optical modulator, the substrate comprising:

[0477] - a plurality of interdigitated drive electrodes (111-114, 121-124), the plurality of interdigitated drive electrodes being applied to the substrate, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of interdigitated drive electrodes being arranged alternately relative to each other on the substrate, the pattern of the plurality of drive electrodes across the substrate comprising a plurality of repeating building blocks, the building blocks comprising:

[0478] - A plurality of interdigitated electrodes extending in at least two directions across the building block, the interdigitated electrodes in the building block forming the drive electrodes, and for at least one electrode among the plurality of interdigitated electrodes in the building block, a maximum length between any two points on the electrode measured along the electrode in the building block is at least twice the diagonal length of the building block unit.

[0479] Item 2. The substrate of Item 1, wherein a calculated pixelation noise metric of a drive electrode pattern of the substrate is below 6.05%, or below 5%, or below 4%.

[0480] Item 3. A substrate according to any one of the preceding items, wherein the electrodes on the substrate include a plurality of nodes, the electrodes are branched at the nodes, the nodes are electrically connected through electrode lines, the plurality of nodes and the connected electrode lines form a tree, the electrode includes at least a first node (201), the electrode is branched into at least three electrode lines at the first node, the first node (201) is directly connected to a second node (202) and a third node (203) through the electrode line, and the electrode is branched into at least three electrode lines at the second node and the third node.

[0481] Item 4. The substrate according to Item 3, wherein:

[0482] - the angle between two directly connected electrode lines has been randomly chosen, and / or

[0483] - the electrode lines directly connected in the building block form a plurality of angles, wherein the angles cover an interval of 0 to 360 degrees, in particular, for each specific interval of at least 30 consecutive angles, there is at least one angle in the plurality of angles that falls within the specific interval, and / or

[0484] - the plurality of nodes have been randomly selected to cover the area of ​​the building block, and / or

[0485] - the electrode lines are straight or curved, and / or

[0486] - The electrode line width is not constant along the electrode line.

[0487] Item 5. The substrate according to any one of the preceding items, wherein:

[0488] - the shortest distance from any point in the substrate to the first driving electrode and the second driving electrode should be lower than a threshold, and / or

[0489] - the sum of the closest distances from any point in the substrate to the first drive electrode and the second drive electrode is lower than a first threshold and / or higher than a second threshold, and / or

[0490] - a distance from a point on the first drive electrode to a point on the second drive electrode is at least a second threshold, and / or

[0491] - The horizontal and / or vertical dimension of the building block is at least 10 times the sum of the electrode line width and the electrode distance.

[0492] Item 6. The substrate according to any one of the preceding items, wherein:

[0493] - the driving electrodes are located in the same plane and do not cross each other, or

[0494] The drive electrodes are crossed in the substrate, and a dielectric separates the crossed drive electrodes at least at the crossing points.

[0495] Item 7. The substrate according to any one of the preceding items, wherein:

[0496] - building blocks are repeated across the substrate in at least two directions, and / or

[0497] - a plurality of different building blocks are repeated across the substrate in one or two directions, and / or

[0498] - two different building blocks are repeated in a checkerboard pattern across the substrate, and / or

[0499] - The substrate comprises non-repeating electrode lines connected to drive electrodes.

[0500] Item 8. The substrate according to any one of the preceding items, wherein:

[0501] - two electrodes in a building block that are not connected in that building block are connected in the substrate via a connection in an adjacent building block, and / or

[0502] - The electrodes in the building block are connected to at least two sides of the building block.

[0503] Item 9. The substrate according to any one of the preceding items, wherein:

[0504] - building blocks are translated with or without mirroring and / or point reflection, and / or

[0505] - A row or column of building blocks is mirrored in its longitudinal direction to form the next row or column of building blocks.

[0506] Item 10. A substrate according to any one of the preceding items, wherein for each drive electrode, at least one drive bus is arranged on the substrate for driving the drive electrode, wherein:

[0507] - for each drive electrode, at least one drive bus is arranged at one side of the substrate to drive the drive electrode, and / or

[0508] - the drive bus is arranged only at said side of the substrate, and / or

[0509] - The drive bus is arranged between the building blocks covering the substrate.

[0510] Item 11. A substrate according to any one of the preceding items, wherein for each driving electrode, at least one driving bus is arranged on the substrate for driving the driving electrode, the at least one driving bus is arranged at one side of the substrate and / or at one side of the building block, and the driving bus includes discontinuous parts, which are connected by driving electrodes driven by the driving bus.

[0511] Item 12. The substrate of any one of the preceding items, wherein at least one of the first drive electrode and the second drive electrode is a spanning tree of a subdivision surface.

[0512] Item 13. A substrate according to any of the preceding items, wherein the drive electrodes have mirror symmetry.

[0513] Item 14. The substrate of any of the preceding items, wherein the substrate is non-rectangular.

[0514] Item 15. An optical modulator, comprising:

[0515] - a first substrate and a second substrate, at least one of the first substrate and the second substrate being the substrate according to any one of items 1 to 14, the first substrate and the second substrate being arranged with their inner sides facing each other, the plurality of driving electrodes (111-114, 121-124) being applied to the inner side of at least one of the first substrate and the second substrate,

[0516] - an optical layer between the first substrate and the second substrate, the optical layer comprising:

[0517] - a fluid comprising particles, wherein the particles are or can be charged;

[0518] - a controller configured to apply electric potentials to the plurality of drive electrodes to obtain an electromagnetic field between the plurality of drive electrodes, the electromagnetic field providing electrophoretic movement of the particles towards or away from one of the plurality of drive electrodes, thereby causing modulation of an optical property of the light modulator.

[0519] Item 16. The optical modulator according to Item 15, wherein:

[0520] - the electrode pattern on the first substrate, the electrode pattern on the second substrate and / or a superposition of the electrode patterns of the first electrode and the second substrate has a calculated pixelation noise metric lower than 6.05%, or 5%, or 4%.

[0521] Item 17. A method of modulating light, comprising:

[0522] - applying an electric potential to drive electrodes applied on two relative substrates to obtain an electromagnetic field between the plurality of drive electrodes, the electromagnetic field providing electrophoretic movement of the particles towards or away from one of the plurality of drive electrodes, thereby causing modulation of light irradiated through the substrates, wherein at least one or both of the two relative substrates are substrates according to any one of items 1 to 16.

[0523] Item 18. A computer-implemented method of calculating a pixelation noise metric for an electrode pattern for a light modulator, the method comprising:

[0524] - Prepare a black and white design image in a specific size, where the electrode line is black and the substrate background is white,

[0525] - Calculate the magnitude and angle of the chirp z-transform (CZT) without scaling using the Bluestein method,

[0526] - determining the maximum intensity in the amplitude spectrum of the linear frequency z-transform (CZT) of the design image as the main peak,

[0527] - determining the second maximum intensity of the amplitude of the chirp z-transform (CZT) excluding the main peak as the higher peak, and

[0528] - calculating the pixelation noise measure as the ratio between the higher peak and the main peak.

[0529] Item 19. A method for calculating a pixelation noise metric according to Item 18, wherein the design image is an 8-bit image in which black is set to 0 and white is set to 255.

Claims

1. A substrate for an optical modulator, the substrate comprising: - at least one drive electrode (111-114, 121-124), the at least one drive electrode applied to the substrate, the drive electrode arranged in a pattern across the substrate, the pattern of the drive electrode across the substrate comprising a plurality of repeating building blocks, the building blocks comprising: - one or more electrodes, the one or more electrodes extending across the building block in at least two different directions, the electrodes in the building block forming the at least one driving electrode, wherein the electrodes in the building block include a plurality of nodes, the electrodes branch at the nodes, the nodes are electrically connected via electrode lines, the plurality of nodes and the connected electrode lines form a tree, the electrodes include at least a first node (201), the electrode branches into at least three electrode lines at the first node, the first node (201) is directly connected to a second node (202) and a third node (203) via electrode lines, the electrode branches into at least three electrode lines at the second node and the third node. 2 . The substrate according to claim 1 , wherein the at least two different directions are orthogonal or inclined relative to each other.

3. A substrate according to claim 1 or 2, wherein for at least one of the electrodes in the building block, the maximum length between any two points on the electrode measured along the electrode in the building block is at least 2 times the length of the diameter of the building block, wherein the diameter is defined as the maximum distance between two points of the building block.

4. The substrate of claim 3, wherein the building blocks are rectangular and the diameter is a diagonal.

5. A substrate according to claim 1 or 2, wherein the calculated pixelation noise metric of the drive electrode pattern of the substrate is less than 6.05%, wherein the pixelation noise metric is defined as the ratio of the maximum intensity among all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum.

6. A substrate according to claim 1 or 2, wherein the calculated pixelation noise metric of the drive electrode pattern of the substrate is less than 5%, wherein the pixelation noise metric is defined as the ratio of the maximum intensity among all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum.

7. A substrate according to claim 1 or 2, wherein the calculated pixelation noise metric of the drive electrode pattern of the substrate is less than 4%, wherein the pixelation noise metric is defined as the ratio of the maximum intensity among all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum.

8. The substrate according to claim 1 or 2, wherein - the angle between two directly connected electrode lines has been randomly chosen, or - the directly connected electrode lines in the building block form a plurality of angles, wherein the angles cover an interval of 0 to 360 degrees and the angles are uniformly selected within the range of 0 to 360 degrees, and / or - the plurality of nodes have been randomly selected to cover the area of ​​the building block, and / or - the electrode lines are straight or curved, and / or - The electrode line width is not constant along the electrode line.

9. The substrate according to claim 1 or 2, wherein: - a building block is repeated across the substrate in at least two different directions, or - a plurality of different building blocks are repeated across the substrate in one or two directions, or - The substrate comprises non-repeating electrode lines connected to drive electrodes.

10. The substrate according to claim 1 or 2, wherein Two different building blocks are repeated in a checkerboard pattern across the substrate.

11. The substrate according to claim 1 or 2, wherein - two electrodes in a building block that are not connected in that building block are connected in the substrate via a connection in an adjacent building block, and / or - The electrodes in the building block are connected to at least two sides of the building block.

12. The substrate according to claim 1 or 2, wherein - building blocks are translated with or without mirroring and / or point reflection, and / or - A row or column of building blocks is mirrored in its longitudinal direction to form the next row or column of building blocks.

13. The substrate according to claim 1 or 2, wherein for each of the at least one driving electrode, at least one driving bus is arranged on the substrate for driving the driving electrode, wherein: - For each drive electrode, at least one drive bus is arranged at one side of the substrate for driving the drive electrode.

14. The substrate according to claim 13, wherein - The drive bus is arranged only at the side of the substrate.

15. The substrate according to claim 1 or 2, wherein for each of the at least one driving electrode, at least one driving bus is arranged on the substrate for driving the driving electrode, wherein: - said at least one drive bus is arranged between said building blocks covering said substrate.

16. A substrate according to claim 1 or 2, wherein at least one driving electrode is isolated from an edge of the substrate, and a through hole is connected to the isolated driving electrode from a surface of the substrate opposite to the driving electrode, for powering the isolated driving electrode and / or connecting the isolated driving electrode to another part of the driving electrode on the substrate.

17. A substrate according to claim 1 or 2, wherein for each driving electrode, at least one driving bus is arranged on the substrate for driving the driving electrode, the at least one driving bus is arranged at one side of the substrate and / or at one side of the building block, and the driving bus includes a discontinuous portion, and the discontinuous portion is connected by the driving electrode driven by the driving bus.

18. The substrate according to claim 1 or 2, wherein the driving electrodes have mirror symmetry.

19. The substrate of claim 1 or 2, wherein the substrate is non-rectangular.

20. The substrate according to claim 1 or 2, wherein the at least one driving electrode is a plurality of driving electrodes, - a plurality of drive electrodes (111-114, 121-124) interdigitated with each other, each of the plurality of drive electrodes being arranged in a pattern across the substrate, the plurality of drive electrodes being arranged alternately relative to each other on the substrate, the pattern of the plurality of drive electrodes across the substrate comprising a plurality of repeating building blocks, the building blocks comprising: - a plurality of interdigitated electrodes extending in at least 2 different directions across the building block, the interdigitated electrodes in the building block forming drive electrodes.

21. The substrate according to claim 20, wherein the plurality of driving electrodes include a first driving electrode and a second driving electrode, wherein: - the shortest distance from any point in the substrate to the first driving electrode and the second driving electrode is below a threshold, and / or - the sum of the closest distances from any point in the substrate to the first drive electrode and the second drive electrode is lower than a first threshold and / or higher than a second threshold, and / or - a distance from a point on the first drive electrode to a point on the second drive electrode is at least a second threshold, and / or - The horizontal and / or vertical dimension of the building block is at least 10 times the sum of the electrode line width and the electrode distance.

22. The substrate according to claim 20, wherein - the driving electrodes are located in the same plane and do not cross each other, or The drive electrodes are crossed in the substrate, and a dielectric separates the crossed drive electrodes at least at the crossing points.

23. An optical modulator comprising: a first substrate, the first substrate being the substrate according to any one of claims 1 to 22, and a second substrate, the first substrate and the second substrate being arranged with their inner sides facing each other, the at least one driving electrode (111-114, 121-124) being applied to the inner side of at least one of the first substrate and the second substrate, - an optical layer between the first substrate and the second substrate, and - a controller configured to apply a potential to the drive electrode, thereby causing modulation of an optical property of the light modulator.

24. An optical modulator according to claim 23, wherein the optical layer includes particles, wherein the particles are charged, and the controller is configured to apply an electric potential to the drive electrode to obtain an electromagnetic field, which provides electrophoretic movement of the particles toward the drive electrode, thereby causing modulation of the optical properties of the optical modulator.

25. An optical modulator comprising: a first substrate, the first substrate being a substrate according to any one of claims 20 to 22, and a second substrate, the second substrate being a substrate according to any one of claims 20 to 22, the first substrate and the second substrate being arranged with their inner sides facing each other, the at least one driving electrode (111-114, 121-124) being applied to the inner side of at least one of the first substrate and the second substrate, - an optical layer between the first substrate and the second substrate, and - a controller configured to apply an electric potential to the drive electrode, thereby causing modulation of the optical properties of the light modulator, and the controller is configured to apply an electric potential to the multiple drive electrodes to obtain an electromagnetic field between the multiple drive electrodes, the electromagnetic field providing electrophoretic movement of particles toward or away from one of the multiple drive electrodes, thereby causing modulation of the optical properties of the light modulator.

26. The optical modulator according to any one of claims 23 to 25, wherein: -The electrode pattern on the first substrate, the electrode pattern on the second substrate and / or the superposition of the electrode patterns of the first substrate and the second substrate has a calculated pixelation noise metric lower than 6.05%, wherein the pixelation noise metric is defined as the ratio of the maximum intensity among all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum.

27. The optical modulator according to any one of claims 23 to 25, wherein: -The electrode pattern on the first substrate, the electrode pattern on the second substrate and / or the superposition of the electrode patterns of the first substrate and the second substrate has a calculated pixelation noise metric of less than 5%, wherein the pixelation noise metric is defined as the ratio of the maximum intensity among all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum.

28. The optical modulator according to any one of claims 23 to 25, wherein: -The electrode pattern on the first substrate, the electrode pattern on the second substrate and / or the superposition of the electrode patterns of the first substrate and the second substrate has a calculated pixelation noise metric of less than 4%, wherein the pixelation noise metric is defined as the ratio of the maximum intensity among all non-zero-order peaks to the maximum intensity of the zero-order peak from the amplitude spectrum.

29. A method of modulating light, comprising: - applying an electric potential to drive electrodes applied on two relative substrates to obtain an electromagnetic field between the drive electrodes, the electromagnetic field providing electrophoretic movement of particles towards or away from one of the plurality of drive electrodes, thereby causing modulation of light irradiated through the substrates, wherein at least one or both of the two relative substrates is a substrate according to any one of claims 1 to 22.

30. A computer-implemented method of calculating a pixelation noise metric of an electrode pattern of a substrate according to any one of claims 1 to 22, the method comprising: - Prepare a black and white design image in a specific size, where the electrode line is black and the substrate background is white, - Calculate the magnitude and angle of the chirp z-transform (CZT) without scaling using the Bluestein method, - determining the maximum intensity in the amplitude spectrum of the linear frequency z-transform (CZT) of the design image as the main peak, - determining the second maximum intensity of the amplitude of the chirp z-transform (CZT) excluding the main peak as the higher peak, and - calculating the pixelation noise measure as the ratio between the higher peak and the main peak.

31. The method of claim 30, wherein the design picture is an 8-bit picture, wherein black is set to 0 and white is set to 255.

Images