Asymmetric driving for optical modulators

Abstract

Some embodiments relate to an electrophoretic optical modulator with asymmetric electrode driving. An alternating current signal is applied to a plurality of electrodes on at least two substrates, resulting in an electric field between the substrates. The amplitude of the alternating current signal is modulated, resulting in a low electric field region moving relative to the electrodes.

Description

Technical Field

[0001] This invention relates to electrophoretic optical modulators, controllers, methods for controlling electrophoretic optical modulators, and computer-readable media. Background Technology

[0002] Optical modulators (such as optically active glass) are known in the art. Typically, an optically active glass system comprises two parallel plates made of a transparent dielectric material (such as glass or plastic). The internal volume defined between the plates can be subdivided into multiple small, independent volumes or individual units filled with a dielectric fluid. The fluid comprises a suspension of particles of the dielectric material, charged material, or material capable of carrying a charge. The surfaces 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 comb-like structures. The electrodes of two interlaced comb-like structures can withstand voltages of the same or opposite polarities. By applying a suitable voltage to the electrodes, particles can be concentrated at different locations between the electrodes, thus giving the system a transparent or opaque appearance.

[0004] Several drawbacks exist that are associated with known systems. Although optically active glass can transition from one state to another (e.g., from transparent to opaque), this transition is time-consuming and typically not perfectly uniform. Furthermore, the lifespan of existing devices is limited. Summary of the Invention

[0005] The embodiments described herein address these and other issues. For example, in one embodiment, the electrophoretic optical modulator includes at least a first substrate and a second substrate, the second substrate being arranged opposite the first substrate. An optical layer is disposed between the first and second substrates, the optical layer comprising a fluid comprising particles that are charged or capable of being charged. A plurality of interdigitated electrodes are arranged across each of the first and second substrates. A controller is configured to apply an alternating current signal to the plurality of electrodes to obtain an electric field between the plurality of electrodes, thereby providing electrophoretic motion of particles toward or from one of the plurality of electrodes, resulting in modulation of the optical properties of the optical modulator. The controller is configured to modulate the amplitude of the alternating current signal applied to the plurality of electrodes on the substrate to cause a low electric field region to move relative to the electrode.

[0006] By modulating the amplitude of the signal, regions with low electric fields (especially the lowest) can be moved within the optical layer. For example, if a signal on one substrate is scaled down while signals on other substrates are not scaled down or are even scaled up, the low electric field region moves toward the previous substrate. Similarly, by manipulating the signals on adjacent electrodes, a low electric field region can be moved parallel to the substrate. In fact, particle movement in the low electric field region may be nonexistent; the particles are stationary relative to the electrodes. Moving such regions allows stationary particles to escape, preventing them from slowing down panel transitions. In particular, so-called dead zones (where no electric field exists) can be moved within the optical layer.

[0007] Moving low-field regions (especially dead zones) has several advantages. Particles in low-field regions do not respond to the electric field as quickly as particles in high-field regions. Therefore, those regions transition slowly and the transition is non-uniform. Furthermore, moving low-field regions back and forth increases overall particle mixing.

[0008] The optical modulators described herein can be applied in a wide range of practical applications. For example, an optical modulator with at most one non-transparent substrate can be used as a surface capable of altering its optical appearance (such as its reflective or transmissive state). In particular, optical modulators with all substrates transparent can be used as optically active glass, for example, in offices, automobiles, enclosures, etc.

[0009] One embodiment of the control method may be implemented on a computer as a computer-implemented method, or implemented in dedicated hardware, or a combination of both. Executable code for one embodiment of the method may be stored on a computer program product. Embodiments of the computer program product include memory devices, optical storage devices, integrated circuits, servers, online software, etc. Preferably, the computer program product includes non-transitory program code stored on a computer-readable medium for executing an embodiment of the method when the program product is executed on a computer.

[0010] In one embodiment, the computer program includes computer program code that, when run on a computer, is adapted to perform all or part of the steps of one embodiment of the method. Preferably, the computer program is implemented on a computer-readable medium. Attached Figure Description

[0011] Further details, aspects, and embodiments of the invention will be described by way of example only and with reference to the accompanying drawings. Elements in the drawings are illustrated for simplicity and clarity and are not necessarily drawn to scale. In the drawings, elements corresponding to those already described may have the same reference numerals. In the drawings:

[0012] Figure 1a An embodiment of one implementation of the substrate is schematically shown.

[0013] Figure 1b An embodiment of one implementation of an optical modulator is schematically shown.

[0014] Figures 1c.1 to 1c.4 An embodiment of one implementation of the scaling factor is illustrated schematically.

[0015] Figure 2a.1 An embodiment of the electric field in one implementation of an optical modulator is shown.

[0016] Figure 2a.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0017] Figure 2b.1 An embodiment of the electric field in one implementation of an optical modulator is shown.

[0018] Figure 2b.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0019] Figure 2c.1 An embodiment of the electric field in one implementation of an optical modulator is shown.

[0020] Figure 2c.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0021] Figures 3a and 3c illustrate an embodiment of the electric field in one implementation of the optical modulator.

[0022] Figure 4a.1 An embodiment of the electric field in one implementation of an optical modulator is shown.

[0023] Figure 4a.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0024] Figure 4b.1 An embodiment of the electric field in one implementation of an optical modulator is shown.

[0025] Figure 4b.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0026] Figures 5a and 5b illustrate an embodiment of the electric field in one implementation of an optical modulator.

[0027] Figure 6a.1An embodiment of the electric field in one implementation of an optical modulator is shown.

[0028] Figure 6a.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0029] Figure 6b.1 An embodiment of the electric field in one implementation of an optical modulator is shown.

[0030] Figure 6b.2 An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0031] Figures 7a to 7c An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0032] Figure 8a An embodiment of one implementation of an optical modulator is schematically shown.

[0033] Figure 8b An embodiment of an AC signal in one implementation of an optical modulator is schematically illustrated.

[0034] Figure 9a An embodiment of one implementation of an optical modulator is schematically shown.

[0035] Figure 9b An embodiment of one implementation of an optical modulator is schematically shown.

[0036] Figure 9c An embodiment of one implementation of a car is illustrated schematically.

[0037] Figure 10 An embodiment of a method for controlling an electrophoretic optical modulator with asymmetric electrode drive is schematically illustrated.

[0038] Figure 11a A computer-readable medium according to one embodiment is schematically illustrated, the computer-readable medium having a writable portion including a computer program.

[0039] Figure 11b A representation of a processor system according to one embodiment is shown schematically.

[0040] Reference list of numbers

[0041] Electrodes 1, 2, 3, and 4

[0042] 10. Optical modulator

[0043] 11 First substrate

[0044] 12 Second substrate

[0045] Electrodes 13, 13a, and 13b

[0046] Electrodes 14, 14a, and 14b

[0047] 15. Fluid

[0048] 16 Controllers

[0049] 30 pieces

[0050] 20 cars

[0051] 21 Optical modulator

[0052] 40 Optical modulator

[0053] 41 First substrate

[0054] 42 Second substrate

[0055] 43 Third substrate

[0056] 46 Controller

[0057] 100 substrates

[0058] 101 First Direction

[0059] 102 Second Direction

[0060] 110 First Electrode

[0061] 120 Second Electrode

[0062] 111-113 Main Line

[0063] Main Line 121-123

[0064] 151 First substrate

[0065] 152 Optical Layers

[0066] 153 Second substrate

[0067] 160 controller

[0068] 1000, 1001 Computer-readable media

[0069] 1010 writable portion

[0070] 1020 Computer Program

[0071] 1110 Integrated Circuits

[0072] 1120 Processing Unit

[0073] 1122 Memory

[0074] 1124 Application-Specific Integrated Circuit

[0075] 1126 Communication Components

[0076] 1130 Interconnect

[0077] 1140 Processor System Detailed Implementation

[0078] While the invention allows for many different embodiments, one or more specific embodiments are shown in the accompanying drawings and will be described in detail herein. It should be understood that this disclosure should be regarded as an exemplary principle of the invention and is not intended to limit the invention to the specific embodiments shown and described.

[0079] In the following text, for ease of understanding, the elements of the implementation scheme are described in the context of operation. However, it will be apparent that the corresponding elements are arranged to perform the functions described herein.

[0080] Furthermore, the invention is not limited to the embodiments, and the invention lies in each of the new features or combinations of features described herein or recited in the different dependent claims.

[0081] Figure 1a An embodiment of a substrate 100 is schematically illustrated, which is used in an optical modulator according to one embodiment. At least two electrodes are arranged in a pattern across the surface of the substrate 100. Figure 1a The diagram shows two electrodes located on the same surface: a first electrode 110 and a second electrode 120. More than two electrodes may exist on the same side of the substrate, for example, to facilitate finer-grained control. For example, multiple electrodes can be used to facilitate segmented substrates, such as those used in segmented optical modulators. For example, in a segmented optical modulator, some regions may have different optical properties, such as different transparency or reflectivity. An embodiment with two electrodes is shown below, but additional electrodes can be added to them, for example, by replicating similar structures that are adjacent to each other.

[0082] The first electrode 110 and the second electrode 120 are applied to the same side of the substrate. The two electrodes are arranged in a pattern across the substrate. One, two, or more electrodes may also be present on the other surface of the substrate 100, for example, to facilitate the stacking of three or more substrates. The electrodes can be applied to the substrate by a planar printing method (e.g., using a mask representing the electrode pattern). The electrodes can also be applied by embedding them into the substrate.

[0083] The first electrode 110 and the second electrode 120 each include multiple main circuits. For example... Figure 1a As shown, the first electrode 110 includes main lines 111, 112, and 113, and the second electrode 120 includes main lines 121, 122, and 123. Typically, each electrode will include more than three lines. The main lines extend across the substrate. The multiple main lines of the first and second electrodes are arranged alternately on the substrate relative to each other. The main lines extend across the substrate in a first direction 101. When viewed in a second direction 102, the main lines from different multiple main lines alternately meet, for example, a first plurality of main lines from the first electrode and a second plurality of main lines from the second electrode alternately meet. The first and second directions form an angle with each other, typically said angle being substantially perpendicular. The first and second directions may each be parallel to the side of the substrate, but this is not necessary.

[0084] For example, substrate 100 can be combined with another substrate to form a transparent optical modulator, at least one of which is transparent. Light incident by the optical modulator is modulated in a manner dependent on particles in an optical layer between the two substrates. In one embodiment, both substrates are transparent to form the light modulator. An encouraging application of substrates (such as substrate 100) is smart glass (e.g., light modulators), which can be used in homes, offices, greenhouses, automobiles, etc.

[0085] The level of transparency or reflectivity of the light modulator can be electrically adapted. For example, in a light modulator (e.g., in smart glass), two substrates (such as substrate 100) are stacked such that the sides with two electrodes applied face each other. A fluid containing particles is confined between the two substrates. Smart glass embodiments are further discussed below. In one embodiment, electrodes (e.g., two or more electrodes) are applied to one surface of each substrate. One, two, or more electrodes may also be present on the other surface of substrate 100, for example, to facilitate the stacking of three or more substrates.

[0086] The following embodiments illustrate examples of modulating transparency or reflectivity levels. The light modulator can be adapted to other optical effects. For example, embodiments can be modified to have different levels of translucency rather than different levels of transparency, if desired. The type of particles used in one embodiment can be changed, for example, to particles that absorb or reflect different wavelengths, and to particles with different degrees of specular or diffuse reflection. For example, in one embodiment, the light modulator can modulate different levels of reflection. The particles can also emit light. Stacking multiple optical layers further increases the possibilities.

[0087] Two sets of alternating main circuits are sufficient to provide electrically adaptable glass; due to the alternating sets, the electric field at any part of the substrate can be controlled, as the two opposing electrodes define portions from two opposing sides.

[0088] Multiple electrodes applied to the substrate are interdigitated to manipulate the electric field between the two substrates. Figure 1a In the diagram, the main electrode is shown as having multiple interdigitated parallel main lines. This is a possible configuration, but in one embodiment, the shape of the electrode can be greatly altered. For example, the diffraction effect can be changed by adapting the shape of the electrode.

[0089] Figure 1b An embodiment of one implementation of an electrophoretic optical modulator is schematically illustrated. The substrate (such as...) Figure 1a The substrate (illustrated in the diagram) can be combined with a similar substrate opposite it (e.g., its mirror image). This optical modulator, in... Figure 1a The schematic intersection of the four electrodes at line AB Figure 1b It is shown in the middle. Figure 1b The diagram shows a first substrate 151 and a second substrate 153, arranged opposite to each other. An optical layer 152 is disposed between the first substrate 151 and the second substrate 153. The optical layer 152 located between the first substrate 151 and the second substrate 153 includes a fluid comprising particles (not shown). The particles are charged or capable of being charged.

[0090] At least two interdigitated electrodes are disposed on a first substrate 151 and a second substrate 153, and the at least two interdigitated electrodes are arranged opposite each other. Two electrodes 1 and 2 are shown on the first substrate 151. For example, electrode 1 may be a main line 111, and electrode 2 may be a main line 121. Two electrodes 4 (opposite to electrode 1) and 3 (opposite to electrode 2) are shown on the second substrate 153. Although not shown, the first substrate 151 may continue with electrode 1, electrode 2, electrode 1, electrode 2, ..., and the second substrate 153 may continue with electrode 4, electrode 3, electrode 4, electrode 3, ... and so on.

[0091] The controller 160 is configured to apply an alternating current signal to each of a plurality of electrodes on two substrates (e.g., to electrodes 1, 2, 3, and 4) to obtain an electric field between the plurality of electrodes. The electric field provides electrophoretic motion of particles toward one of the plurality of electrodes, or provides electrophoretic motion of particles from one of the plurality of electrodes, to result in modulation of the optical properties of the light modulator. Figures 2a.1 to 6b.2 The numbering of the middle electrode is the same as that of the middle electrode in the cross section.

[0092] The controller 160 is configured to control and / or generate an asymmetric AC signal for an electrophoretic optical modulator.

[0093] Controller 160 is configured to apply an alternating current signal to a plurality of electrodes to obtain an electric field between the electrodes, thereby providing electrophoretic motion of particles toward one of the electrodes, or providing electrophoretic motion of particles from one of the electrodes, to result in modulation of the optical properties of the optical modulator. For example, controller 160 may generate an alternating current signal. For example, in the case where each substrate has two electrodes, controller 160 may be configured to generate a set of four alternating current signals for application to the electrodes. Application may be direct from controller 160 to the electrodes. Application may also be indirect from controller 160 to the electrodes, for example, through intermediate processing devices such as amplifiers and / or filters.

[0094] Many optical properties can be modulated in an optical modulator; for example, transparency, reflectivity, color, etc. For simplicity, the implementation is described in terms of controlling grayscale between complete transparency and complete opacity. However, those skilled in the art will understand that different optical properties can be manipulated by using different particles and / or different substrates. Particles are sometimes referred to as pigments.

[0095] The controller 160 is configured to modulate the amplitude of an alternating current signal applied to a plurality of electrodes on a substrate to cause a low electric field region to move relative to the electrodes.

[0096] During the conventional driving of the electrodes in an optical modulator (including during AC driving), the electric field potential reveals regions within the optical layer where the electric field is significantly lower than in other regions. These low-field regions are disadvantageous because particles within them are difficult to control. In particular, particles move more slowly in these low-field regions due to the low electric field. Much of the time required to transition from one optical state to another is caused by the slow movement of particles in these low-field regions.

[0097] For example, the electric field strength in the low-electric-field region of the optical layer may be only 25% or less of the electric field strength at other locations in the optical layer. For example, compared to the maximum electric field in the optical layer, the electric field strength in some regions of the optical layer may be only 15% or less, 10% or less, 1% or less, etc. For example, the electric field strength in the low-electric-field region of the optical layer may be less than 2. 10^6 V / m, less than 1 10^6 V / m, less than 1 10^5 V / m, etc. For example, a low electric field region can be considered as the region with the smallest electric field in the optical layer. For example, a low electric field region can be considered as the region with the smallest electric field in the optical layer or a predetermined percentage (e.g., at most 10%, at most 15%, etc.) larger than the smallest electric field.

[0098] Electric fields can be measured directly, but computer simulations of electric fields have proven to be accurate enough for practical applications. For example, the well-known COMSOL software can be used to simulate electric field diagrams. Here, the strength of the electric field is generated using electrostatic studies based on the AC / DC module of COMSOL Multiphysics. The electric field diagram shown in this article was created using the software mentioned above.

[0099] In particular, there can be regions within the optical layer where no electric field exists, such as zero or substantially zero electric field. These regions are called dead zones. Particles in dead zones are essentially unresponsive to electrophoretic control. Particles can be deflected out of the dead zone by other methods (e.g., slow entropy shift) and become susceptible to controlled shifts again. Dead zones are particularly problematic for rapid transitions between optical modes in optical modulators. Dead zones are sometimes referred to as electric field neutral zones or neutral points. A neutral point can be a point in a 2D intersection as shown in the figure; however, in physically 3D implementations, a neutral point can be a neutral curve or a neutral volume.

[0100] In this implementation, the problem caused by low electric field regions, especially dead zones, is addressed by varying the potential difference between the electrodes. This electric field neutral point, or neutral volume, is shifted within the optical layers between the substrates by modulating the relative amplitude of the signal applied to the electrodes.

[0101] In one implementation, the overall drive can use an AC signal and maintain current neutrality and balance in multiple electric fields on time. This is advantageous because it reduces corrosion of the electrodes.

[0102] In one embodiment, the electric field lines are modulated such that the neutral point is offset in the optical layer to increase the total volume under the influence of the electric field (e.g., electrophoretic control).

[0103] In one implementation, the primary parameter that changes in the signal is amplitude, such as the signal amplification level. Other parameters that change asymmetrically between the electrodes include frequency, signal shape (square, sinusoidal, etc.), duration, and phase.

[0104] The advantage of asymmetric driving of electrodes (as further explained herein) is faster transitions between optical states. Asymmetric driving of electrodes further provides the advantage of more uniform transitions because the difference between slow and fast transition positions on the panel is reduced. An additional advantage of asymmetric driving is reduced particle accumulation on the electrodes. In conventional optical modulators (especially DC-driven modulators), particles can accumulate on the electrodes and become locally tightly bound. This leads to particle interactions and the formation of irreversible aggregates. Such aggregates are undesirable. Aggregation effects cause problems such as non-uniformity and gravitational effects. However, in the case of asymmetric driving as in one embodiment, particles become increasingly mobile, thus limiting the gradual cooling to aggregates. Furthermore, particle movement is more uniform.

[0105] Dead zones (e.g., neutral points or neutral volumes) also contribute to optical aberrations as particles accumulate during operation. By increasing particle mobility, aggregation is reduced, and particles are less likely to fall due to gravity. Improved particle mobility allows particles to better approach and disperse to achieve a non-transparent state while maintaining a particle distribution closer to its initial state at the time of manufacturing.

[0106] Interestingly, asymmetric driving can be added to existing algorithms used to drive a panel to a target grayscale. Furthermore, introducing asymmetric driving can still maintain current neutrality. For example, algorithms such as those described in PCT / EP2021 / 071346 entitled "Light Modulator, LightModulator Method And Smart Glazing" can be used, and signal scaling can be introduced to move low electric field regions, especially dead zones.

[0107] For example, the controller may be configured with a set of algorithms for, for example, one or more of the following functions: increasing transparency, decreasing transparency, maintaining current transparency, etc. More or fewer algorithms may be present. For example, the algorithms may vary depending on the magnitude of the desired transparency jump. For example, the maintenance algorithm may be omitted. For example, in a simplified embodiment, the controller may have an algorithm for driving towards complete transparency and an algorithm for driving towards complete opacity. For example, computer program code may be stored in the controller's memory to implement the algorithms. In one embodiment, the controller is configured to apply a programmable driving algorithm for a period of time, which may depend on the current transparency, the target transparency, and measured sensor values ​​(e.g., as explained in the cited PCT application).

[0108] Existing algorithms can be modified by periodically scaling down or up one or more signals to move low-field regions, especially dead zones. For example, existing driving algorithms can be modified to be asymmetric by introducing asymmetric scaling and changing the direction of the asymmetric scaling after a predetermined period. The low-field region moves as the asymmetry of the drive changes. In one implementation, a volume in the optical layer is scanned with higher-intensity electric field lines, causing all particles in the volume to be susceptible to electrical control at a point during the scan. Asymmetric driving can be advantageously used to drive towards target transparency and to maintain grayscale. The drive can also be varied asymmetrically while maintaining grayscale.

[0109] Asymmetric actuation allows for faster transitions, especially very fast device shutdown (i.e., actuation towards opacity), because a larger portion of the particle group is moved regardless of the initial position of the particles, which includes the intermediate position between the electrodes and the electrode surfaces.

[0110] Typically, signal scaling is applied to paired electrode signals. For example, a pair of signals X and Y can be applied to a pair of electrodes. The electrodes can be, for example, a pair of opposing electrodes, a pair of adjacent electrodes, or a pair of diagonally opposite electrodes. Before scaling, the electrode signals typically have the same phase and the same amplitude; in fact, the pair of signals can be identical signals. However, even before scaling, there can be differences in phase or amplitude. For example, phase differences can be used to trap particles. For example, scaling differences can be used to compensate for hardware differences, such as substrate magnification. In particular, signals X and Y can be conventional AC drive signals used in electrophoretic optical modulators. Signals X and Y can be scaled to move low-electric-field regions in the optical layer. For example, a time-varying scaling factor can be applied to the signals. Figures 1c.1 to 1c.4 An embodiment of one implementation of the scaling factor is illustrated schematically.

[0111] exist Figure 1c.1 In this implementation, the scaling factors are selected such that one signal is amplified (increased) while another signal is scaled down (decreased). In one implementation, the product of the scaling factors can be 1. In another implementation, the sum of the logarithms of the scaling factors can be 0.

[0112] exist Figure 1c.2 In this diagram, the scaling factor is chosen such that only one of the two signals is increased while the other remains constant. In the accompanying drawings, scaling alternates. Note that in these embodiments, scaling down can be used instead of scaling up. In fact, using scaling down is easier because the signal remains within predetermined limits.

[0113] Figure 1c.3 and Figure 1c.2The same applies, except that the periods of scaling and periods without scaling are alternated.

[0114] exist Figure 1c.4 In this case, only one of the signals is scaled, while the other remains constant. Figure 1c.5 In this case, only one of the signals is scaled, while the other remains constant. Figure 1c.5 In this process, the signal is alternately amplified and scaled down proportionally. In this embodiment, scaling and non-scaling time periods are combined.

[0115] Many other variations are possible. For example, a scaling factor with a small amount of noise can be added to slightly randomize the location of the low electric field region. These embodiments use a trigonometric transformation scaling factor, but other shapes are possible, such as square waves, sine waves, etc.

[0116] Figures 2a and 2c schematically illustrate an embodiment of an AC signal in one implementation of an optical modulator, which is arranged to close the panel, i.e., to reduce the transparency of the panel. Figure 2a.1 , Figure 2b.1 and Figure 2c.1 An embodiment of the electric field in one implementation of an optical modulator is shown. The electric field is as follows: Figure 1b It is shown in the same plane as shown. Figure 2a.2 , Figure 2b.2 and Figure 2c.2 An embodiment of an AC signal corresponding to an electric field diagram is schematically illustrated. Note that... Figure 2a.2 , Figure 2b.2 and Figure 2c.2 The scaled signal is illustrated schematically, while Figures 1c.1 to 1c.4 The scaling factor is illustrated schematically.

[0117] The movement of particles is largely controlled by the electric field and its shape (as indicated by the electric field diagram), although some other factors can also have some influence on the movement of particles, such as Brownian motion, temperature, etc.

[0118] Figure 2a.2 The y-axis (and similar figures) schematically indicates the voltage of the signal applied to the electrodes. The horizontal dashed lines in the four signals indicate the neutral voltage, such as the zero-voltage line for each signal. The x-axis schematically indicates time. Note that the four signals are AC signals. Figure 2 shows a square signal, but other types of AC signals (such as triangular, sinusoidal, and combinations thereof) can be used. Figure 2a.2 The drive shown is configured to turn off the optical modulator, for example, by reducing transparency or increasing grayscale levels. If Figure 2a.2If the drive shown is continued for an extended period, the substrate will eventually approach its maximum opacity. However, continuous drive until complete opacity is not required; the drive can be terminated at a desired grayscale level before that point.

[0119] Note that signals 1 and 4 are equal, creating a dead zone midway between substrates 1 and 4. The same applies to signals 2 and 3. Particles in the dead zone do not respond to the electric field because there is no electric field there. Near the zero electric field point, the electric field is low, for example, a low-field region exists. Particles in the low-field region respond to the electric field, but the response is very slow.

[0120] During the shutdown operation, as shown in Figures 2a to 2c, the low electric field region includes a dead zone between substrates, such as within the optical layer. This dead zone is moved by introducing asymmetry during actuation.

[0121] exist Figure 2a.2 In this case, the AC signals applied to opposite electrode pairs 1 and 4 are equal to the AC signals applied to opposite electrode pairs 2 and 3. Figure 2a.2 In this example, the AC signals applied to adjacent electrode pairs 1 and 2 are equal to those applied to adjacent electrode pairs 4 and 3, except that the phase shift is greater than 180 degrees. A relative electrode pair is two different electrodes facing each other on opposite substrates. An adjacent electrode pair is two different electrodes adjacent to each other on the same substrate. There is a dead zone between electrode 1 and electrode 4, and also between electrode 2 and electrode 3.

[0122] Figure 2b.2 This illustrates the asymmetry introduced when driving the panel. Figure 2b.2 In this context, except for scaling, the AC signals applied to opposite electrode pairs 1 and 4 are equal to the AC signals applied to opposite electrode pairs 2 and 3, except for scaling. For example, by scaling down the drive on electrodes 1 and 2 (e.g., by scaling down the drive of one electrode in a pair of opposite electrodes), it is possible to... Figure 2a.2 Driver acquisition in Figure 2b.2 The signal is driven by [the signal generator]. In this example, the signals from electrode 1 and electrode 2 have been scaled down. Scaled-down or amplified signals can be achieved using an amplifier, a variable resistor, or by changing parameters in the signal generator. Figure 2b.2 In this example, the AC signals applied to adjacent electrode pairs 1 and 2 are equal to the AC signals applied to adjacent electrode pairs 4 and 3, except that the phase shift is more than 180 degrees.

[0123] Figure 2b.2 The effect of the drive shown is still to close the panel. Note that... Figure 2a.1 The low electric field region in the middle has been Figure 2b.1The center has moved upwards; in particular, the dead zone has moved upwards.

[0124] exist Figure 2c.2 In this case, the scaling direction is reversed. During the shutdown operation, the asymmetry introduced in a pair of opposing electrodes is now in opposing directions. This means that the dead zone is now moved downwards, for example, toward the bottom substrate. Note that the upward direction is opposite to the downward direction. These terms refer to the panel as shown in the figure and are short for "towards the first substrate" or "towards the second substrate"; in one embodiment, the panel may be vertical so that directions such as upward and downward can be forward and backward or the like.

[0125] To reduce transparency (e.g., to turn off the panel), the panel can be driven by alternating between three types of signals. For example, the drive may have a center dead zone as shown in Figure 2a, a top dead zone as shown in Figure 2b, or a bottom dead zone as shown in Figure 2c. For example, in one embodiment, the drive may repeat a cycle of, for example, center dead zone drive, top dead zone drive, center dead zone drive, and bottom dead zone drive.

[0126] Using this type of bidirectional asymmetric drive to turn off the panel allows for significantly faster achievement of deep gray. In the case of conventional symmetric drive, the time required to transition from 10% grayscale to 1% grayscale (that is, from light gray to full black) is approximately ten times longer than in one implementation.

[0127] Using bidirectional asymmetric drive is preferred because a larger portion of the volume is scanned, thus improving particle mixing. Although not mandatory, improved drive can be achieved by repeating cycles such as middle dead zone drive and top dead zone drive.

[0128] Figures 3a and 3c illustrate an embodiment of the electric field in one implementation of the optical modulator. The electric field diagrams in Figures 3a and 3c are... Figures 2a.1 to 2c.1 The electric field diagrams are the same. Figures 3a to 3c show the low electric field regions indicated by circles. The center of the circle corresponds to a portion of the field (where no electric field exists, such as a dead zone). Note that the position of the dead zone is moved relative to the electrode. In this example, the dead zone is moved generally orthogonally to the substrate. Orthogonal movement is convenient, although not necessary; the dead zone can also be moved parallel to the substrate by introducing asymmetry in a pair of adjacent electrodes and in a pair of opposing electrodes. However, orthogonal movement is sufficient to improve mixing.

[0129] Figures 3a and 3c illustrate different stages of asymmetric actuation during the shutdown operation. The dead zone moves within the optical layer between two opposing substrates, for example, toward or away from either substrate. For example, a controller may be configured to apply a scaling operation to a signal applied to electrodes. For example, the signals applied to opposing electrodes may be identical, except that scaling is applied to one or both of them. The amount of scaling depends on the application, for example, on the size of the panel and the thickness of the optical layer. As one embodiment, a first AC signal applied to a first electrode may be scaled relative to a second AC signal applied to (e.g., opposite the first electrode) a second electrode, wherein the lower amplitude of the first AC signal and the second AC signal is at most 70%, 50%, 45%, 40%, or 30% of the higher amplitude.

[0130] The signal schematically shown in the figure is a square wave, although this is not strictly necessary in practice. Alternatively, the signal could be a sine wave. For example, a low-pass filter could be applied to the signal shown. The low-pass threshold could be chosen to depend on the size of the panel, for example, 1 kHz for a larger panel.

[0131] For example, in one embodiment, the controller may have a signal generator configured for a dead zone at the midpoint of the optical layer. An asymmetric modulator can modulate the signal to move the dead zone toward or away from one of the substrates. The asymmetric modulator can cycle through different scaling factors. For example, scaling between two AC signals applied to a pair of opposing electrodes can cycle between a lower scaling factor and a higher scaling factor. The controller may also directly generate a scaled signal.

[0132] Scaling allows one signal to remain constant while decreasing and / or increasing another signal. For example, a first AC signal may have a constant amplitude, and a second AC signal may be scaled relative to the first AC signal. The constant signal and the scaled signal can be switched on time. Scaling can be performed on low-voltage signals, but can also be introduced during signal amplification. In one embodiment, the signal scaling is randomized, thereby randomizing the location of the dead zone. In one embodiment, the signal scaling is controlled, thereby moving the location of the low-electric-field region in a controlled manner, for example, along a predetermined path through an optical layer.

[0133] Once the target grayscale level is reached (e.g., as indicated by sensors associated with the panel, such as optical and / or electrical sensors), the drive signal can be stopped. The panel will maintain its grayscale level for a period of time (although the panel's appearance may degrade over time), allowing the use of conventional sustain drive. Sustain drive may involve slowly and with low power driving the panel to a grayscale level close to the target grayscale level. Sustain drive may alternate with no drive at all. During sustain, asymmetric signals may also be used, as this will improve blending and increase the panel's durability.

[0134] Figures 4a and 4b schematically illustrate an embodiment of an AC signal in one implementation of an optical modulator, which is arranged to open a panel, i.e., increase the transparency of the panel. Figure 4a.1 and Figure 4b.1 An embodiment of the electric field in one implementation of an optical modulator is shown. The electric field is in relation to... Figure 1b It is shown in the same plane as shown. Figure 4a.2 and Figure 4b.2 An embodiment of an AC signal corresponding to an electric field diagram is illustrated schematically.

[0135] exist Figure 4a.2 In this case, the AC signals applied to adjacent electrode pairs 1 and 2 are equal to the AC signals applied to adjacent electrode pairs 3 and 4. Figure 4a.2 In this example, the AC signals applied to opposite electrode pairs 1 and 4 are equal to the AC signals applied to opposite electrode pairs 2 and 3, except that a phase shift occurs, which in this example exceeds 180 degrees. A low electric field region exists midway between electrode 1 and electrode 2, and a low electric field region exists midway between electrode 3 and electrode 4, the low electric field regions extending from the substrate to the substrate. Figure 4a.1 Two dead zones are also shown: the dead zone between electrode 1 and electrode 2, and the dead zone between electrode 3 and electrode 4. These two dead zones are located on the outer side of the optical layer. Since there are no particles associated with the illustrated electrodes 1 to 4, these dead zones themselves are not a problem. However, a low-field region extends between these two dead zones. Particles in the low-field region respond to the electric field faster than those in the dead zones, but the particles in the low-field region still move slower than those at other locations in the optical layer. For example, the electric field in the low-field region between the two dead zones can be 25% lower than the field directly located in the middle between the electrodes.

[0136] Figure 4b.2 This illustrates the asymmetry introduced when driving the panel. Figure 4b.2In this process, the AC signals applied to adjacent electrode pairs 1 and 2 are equal to the AC signals applied to adjacent electrode pairs 3 and 4, except for scaling. For example, by scaling down the drive on electrodes 2 and 3 (e.g., by scaling down the drive of one electrode in a pair of adjacent electrodes), it is possible to... Figure 4a.2 Driver acquisition in Figure 4b.2 The driving mechanism is as follows. In this example, the signals from electrodes 2 and 3 have been scaled down. Figure 4b.2 In this example, the AC signals applied to the opposite electrode pairs 1 and 4 are equal to the AC signals applied to the adjacent electrode pairs 2 and 3, except that the phase shift exceeds 180 degrees.

[0137] Figure 4b.2 The effect of the drive shown is still to open the panel. Note that in Figure 4b.1 middle, Figure 4a.1 The low electric field region has shifted to the right. The size of the low electric field region has also increased slightly. If only using... Figure 4b.2 The type of drive shown in the diagram would make it more difficult to move particles near electrodes 2 and 3, but this is not a problem because the drive is combined with an asymmetric drive in another direction.

[0138] exist Figure 4b.2 In this process, the scaling direction can also be reversed, for example, by scaling down signals 1 and 4 proportionally, but not proportionally scaling down signals 2 and 3. During the open operation, the asymmetry introduced in a pair of adjacent electrodes will therefore be in opposite directions; for example, the low electric field region will move to the left.

[0139] To increase transparency (e.g., to open the panel), the panel can be driven by alternating between three types of signals. For example, the drive could have a central low-electric field region as shown in Figure 4a, a right-side low-electric field region as shown in Figure 4b, or a left-side low-electric field region (not shown in a separate figure). For example, in one embodiment, the drive could cycle repeatedly between low electric fields at the following locations: center, left, center, right; or only center, left. The time spent in each phase does not need to be equal. To open, the time spent at the center can be longer than the time spent driving with a left-side or right-side low-electric field.

[0140] In one implementation, during the turn-on operation, the low electric field region can be moved parallel to the substrate. Similar options for generating signals, as discussed with respect to the turn-off operation, are also possible for the turn-on operation. For example, the signal can be scaled, and the scaling factor can be repeatedly applied across a scaling factor range.

[0141] Figures 5a and 5b illustrate an embodiment of the electric field in one implementation of the optical modulator. The electric field diagrams in Figures 5a and 5b are... Figures 4a.1 to 4b.1The electric field diagrams are the same. Figures 5a to 5c show the low electric field regions schematically indicated by ellipses. The electric field in the ellipse is approximately 1.5. 10^6 V / m. Comparing Figures 5a and 5b, it is noted that the low electric field region is shifted to the right. For example, the center of the low electric field region (e.g., the centroid or the center weighted by the electric field strength) is shifted to the right, in this instance, the shift being parallel to the substrate. It is also noted that the dead zone located outside the optical layer is shifted to the right.

[0142] Figures 6a and 6b schematically illustrate an embodiment of an AC signal in one implementation of an optical modulator arranged for diagonal driving. Diagonal driving can be used to close the panel. Diagonal driving can be used to mix particles in the optical layer. Mixing particles is advantageous for the panel's lifespan. Mixing particles can also be used as a phase during panel closure. For example, a cycle of diagonal driving as shown in Figures 6a and 6b can be followed by driving as shown in Figures 2a to 2c. Diagonal driving can also be used to achieve a grayscale between closing and opening the panel.

[0143] Figure 6a.1 and Figure 6b.1 An embodiment of the electric field in one implementation of an optical modulator is shown. The electric field is in relation to, as... Figure 1b It is shown in the same plane as shown. Figure 6a.2 and Figure 6b.2 An embodiment of an AC signal corresponding to an electric field diagram is illustrated schematically.

[0144] exist Figure 6a.2 In this case, the AC signals applied to diagonal electrode pairs 1 and 3 are equal to the AC signals applied to diagonal electrode pairs 2 and 4. Figure 6a.2 In this example, the AC signals applied to adjacent electrode pairs 1 and 2 are equal to those applied to adjacent electrode pairs 3 and 4, except for a phase shift, which in this case exceeds 180 degrees. A dead zone exists midway between electrodes 1, 2, 3, and 4. Within the dead zone, the electric field is largely empty.

[0145] Figure 6b.2 This illustrates the asymmetry introduced when driving the panel. Figure 6b.2 In this process, the AC signals applied to diagonal electrode pairs 1 and 3 are equal to the AC signals applied to diagonal electrode pairs 2 and 4, except for scaling. For example, by scaling down the drive on electrodes 1 and 2 (e.g., by scaling down the drive of one electrode in a pair of diagonal electrodes), it is possible to... Figure 6a.2 Driver acquisition in Figure 6b.2 The driver in. In Figure 6b.2In this example, the AC signals applied to adjacent electrode pairs 1 and 2 are equal to those applied to adjacent electrode pairs 3 and 4, except for a phase shift, which in this instance exceeds 180 degrees. Note that all signals applied to the electrodes on one substrate (in this example, the upper substrate) have been scaled down. For example, in one embodiment, the amplitude of the signal applied to one of the two substrates is lower than the amplitude of the signal applied to the other substrate. Therefore, Figure 6a.1 The dead zone in the middle has been Figure 6b.1 The dead zone is moved upwards. In this example, the dead zone is orthogonal to the substrate movement, although non-orthogonal movement is also possible, for example, by adjusting the... Figure 6b.2 Signal 1 and signal 2 are scaled by different amounts.

[0146] In one embodiment, the controller is configured for a shutdown operation of the optical modulator, in which AC signals applied to opposing electrodes on opposing substrates are scaled relative to each other, and the controller modulates the scaling to shift a low electric field region. In another embodiment, AC signals applied to adjacent electrodes on the same substrate are phase-shifted relative to each other.

[0147] In one embodiment, the controller is configured for an on operation of the optical modulator, wherein in a off operation, AC signals applied to adjacent electrodes on the same substrate are scaled relative to each other, and the controller modulates the scaling to move a low electric field region. In one embodiment, AC signals applied to opposing electrodes on opposing substrates are phase-shifted relative to each other.

[0148] In one implementation, asymmetric driving involves applying different amplitude signals to at least some electrodes in an optical modulator. Other types of asymmetric driving are also possible, such as asymmetric driving with different frequencies. For example, the same amplitude can be used on all electrodes, but the frequency can be varied between at least some electrode pairs. In addition to amplitude, the frequency can also be varied.

[0149] In one embodiment, the optical modulator is an electrophoretic modulator, in which particles are moved due to the electrophoretic effect. In one embodiment, a high-frequency component may be added to the signal. For example, in one embodiment, the electrophoretic drive uses a frequency, such as up to 100 Hz. Using only a lower frequency signal is sufficient to achieve effective drive of the optical modulator. In one embodiment, at least some of the AC signal includes a high-frequency component. For example, in one embodiment, the high-frequency component may have a frequency of at least 500 Hz, or at least 750 Hz, preferably at least 1 kHz. Due to both dielectrophoresis and electrophoresis, the high-frequency component causes particle movement.

[0150] When the target gray level is reached, high-frequency components can be removed. This saves energy and reduces the temperature rise of the optical modulator. Low-pass filters can be applied to AC signals. For example, a low-pass filter can be set to a threshold frequency that is just above the high-frequency components. Figures 7a to 7c An embodiment of an AC signal in one implementation of an optical modulator is illustrated schematically. Figures 7a to 7c Corresponding to the illustrative HF component Figure 2a.2 , Figure 2b.2 , Figure 2c.2 . Figure 4a.2 , Figure 4b.2 , Figure 6a.2 and Figure 6b.2 HF components can also be used for enhancement.

[0151] Figure 8a An embodiment of one implementation of an optical modulator is schematically shown. Figure 8b An embodiment of an AC signal in one implementation of an optical modulator is schematically shown. Other optical modulators shown in the figures use two phases for all signals. However, this is not necessary; in fact, it can be advantageous to use different phases for more than two signals. For example, Figure 8b The first signal on the electrode is shown. The second signal on the adjacent electrode 2 is the same, but shifted by a first phase shift. The third signal on electrode 3 is the same as the signal on electrode 2, but shifted by a second phase shift. Compared to signal 3, the signal on electrode 4 is phase-shifted by a third phase shift. The first signal and the fourth signal, shifted by a fourth phase shift, are the same. All four phase shifts can be equal to 360 / 4 = 90 degrees, but this is not necessary. In one embodiment, the phase difference changes over time.

[0152] The advantage of increasing the phase shift of the four signals is that the particles are better retained within the cell gaps. Therefore, a given level of transparency or no transparency can be maintained with lower power. Figure 8b In the diagram, the amplitudes of the four signals are equal, but in one embodiment, the amplitudes may be altered.

[0153] Using different phases for two or more signals can be used to capture particles in the gap between adjacent electrodes; this is especially advantageous when the panel is closed and a gray level is maintained.

[0154] For example, taking the signal on electrode 4 as a reference, signal 1 may have a phase shift and amplitude scaling, signal 2 may have another phase shift and amplitude scaling (possibly the same scaling), and signal 3 may have another phase shift without amplitude scaling.

[0155] Figure 9aAn embodiment of an optical modulator 10 is schematically illustrated, which can be applied in smart glass. The optical modulator is one embodiment of an optical modulator.

[0156] Reference is made to patent application PCT / EP2020 / 052379, which is incorporated herein by reference; this application includes an advantageous design of an optical modulator that can be further improved, for example, by including electrodes, building blocks and / or substrates as explained herein.

[0157] The optical modulator 10 can be electrically switched between a transparent state and a non-transparent state, and between a non-transparent state and a transparent state, or it can be electrically switched between a reflective state and a non-reflective state, and between a non-reflective state and a 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 to the inner side of the first substrate 11: electrodes 13a and 13b are shown. These at least two electrodes are collectively referred to as electrode 13. At least two electrodes are applied to the inner side of the second substrate 12: electrodes 14a and 14b are shown. These at least two electrodes are collectively referred to as electrode 14. The electrode configuration is interdigitated, but can be greatly modified in other aspects. In particular, it is not necessary for the main lines of the electrodes to extend parallel across the substrate.

[0158] A fluid 15 is disposed between the substrates. The fluid includes particles 30, such as nanoparticles and / or microparticles, wherein the particles are charged or capable of carrying a charge. For example, the particles may inherently carry a charge on their surface. For example, the particles may be surrounded by charged molecules.

[0159] The electrodes are arranged to drive the particle 30 toward or away from the electrodes in response to an applied electric field. The optical properties of the light modulator, particularly its transparency or reflectivity, depend on the position of the particle 30 in the fluid. For example, a connector may be provided to apply an electromagnetic field to the electrodes.

[0160] In one embodiment, substrates 11 and 12 may be optically transparent (except for the electrodes), typically >95% transparent at the relevant wavelengths, for example >99% transparent. Taking the electrodes into account, the transparency would be much lower, for example, 70%. The term "optical" may refer to wavelengths visible to the human eye (about 380 nm to about 750 nm) (where applicable), and may also refer to a wider range of wavelengths (including infrared (about 750 nm to 1 μm) and ultraviolet (about 10 nm to 380 nm) and sub-options thereof) (where applicable). In one exemplary embodiment of the optical modulator, the substrate material is selected from glass and polymers. Transparent materials may also be used for the electrodes. In one embodiment of the optical modulator, only substrates 11 and 12 are transparent.

[0161] In another embodiment, one substrate (such as bottom substrate 12) may be reflective or partially reflective, while top substrate 11 is transparent. The optical properties of the light modulator, particularly the reflectivity, depend on the position of the particles 30 in the fluid. When the panel is in the open state (vertically driven), the particles will be mostly located between the opposing electrodes of the two substrates, allowing incident light to travel relatively unimpeded through the transparent top substrate and optical layer, and to be reflected or partially reflected on the bottom substrate.

[0162] 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 optical 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, and even more preferably less than 50 μm, such as less than 30 μm.

[0163] In one embodiment, the modulator may be disposed in a flexible polymer, and the remainder of the device may be disposed in glass. The glass may be rigid or flexible glass. If desired, a protective layer may be disposed on a substrate. If more than one color is provided, more than one layer of flexible polymer may be provided. The polymer may be polyethylene naphthalate (PEN), polyethylene terephthalate (PET) (optionally having a SiN layer), polyethylene (PE), etc. In another embodiment, the device may be disposed in at least one flexible polymer. In this way, the modulator can be attached to any surface, for example, by using an adhesive.

[0164] Particle 30 may be adapted to absorb light, thereby preventing certain wavelengths from traveling through it. Particle 30 may reflect light; for example, the reflection may be specular, diffuse, or something in between. The particle may absorb some wavelengths and reflect others. The particle may additionally or alternatively emit light, for example, using phosphorescence, fluorescence, etc. Even fluids may emit light, and the emissivity of the light may be modulated by changing the position of the particles.

[0165] In one exemplary embodiment of the optical modulator, the nanoparticles have a size of 20 nm to 1000 nm, preferably 20 nm to 300 nm, and more preferably less than 200 nm. In one exemplary embodiment of the optical modulator, the nanoparticles / microparticles may include a coating and / or pigment, and preferably include a core. In one exemplary embodiment of the optical modulator, the coating of the particles is made of a material selected from conductive and semiconductive materials.

[0166] In one exemplary embodiment of the optical modulator, the particles are adapted to absorb light with wavelengths from 10 nm to 1 mm, such as light from 400 nm to 800 nm, 700 nm to 1 μm, and 10 nm to 400 nm, and / or to absorb a portion (filter) of light with wavelengths in the range of 10 nm to 1 mm, as well as combinations thereof.

[0167] In one exemplary embodiment of the optical modulator, the particles are charged or capable of being charged. For example, the charge on the particles can be from 0.1e to 10e per particle (5). 10⁻⁷ to 0.1 C / m²).

[0168] In one exemplary embodiment of the optical modulator, the amount of fluid present is from 1 g / m² to 1000 g / m², preferably from 2 g / m² to 75 g / m², more preferably from 20 g / m² to 50 g / m², such as from 30 g / m² to 40 g / m². A significant advantage is that, with the layout of the present invention, less fluid can be used, and similarly, fewer particles can be used.

[0169] In one exemplary embodiment of the optical modulator, the amount of particles present is from 0.01 g / m2 to 70 g / m2, preferably from 0.02 g / m2 to 10 g / m2, such as from 0.1 g / m2 to 3 g / m2.

[0170] In one exemplary embodiment of the optical modulator, the color of the particles is selected from cyan, magenta and yellow, as well as from black and white, and from combinations of the above colors.

[0171] In one exemplary embodiment of the optical modulator, the fluid includes one or more of surfactants, emulsifiers, polar compounds, and compounds capable of forming hydrogen bonds.

[0172] Fluid 15 may be a nonpolar fluid with a dielectric constant less than 15. In one exemplary embodiment of the optical modulator, the fluid has a relative dielectric constant r less than 100, preferably less than 10, such as less than 5. In one exemplary embodiment of the optical modulator, fluid 15 has a dynamic viscosity greater than 10 mPa·s.

[0173] Electrodes 13a, 13b and 14a, 14b are in fluid contact with the fluid. The fluid may contact the electrodes directly or indirectly, for example, by passing the fluid through a porous layer to bring a second medium into contact with the electrodes. In one embodiment, the electrodes cover approximately 1% to 30% of the substrate surface. In one embodiment, the electrodes comprise a conductive material with a resistivity of less than 100 nm at 273 K (for comparison, ITO typically used has 105 nm), which is analogous to a conductivity >1 at 20ºC. 107 S / m.

[0174] In one embodiment of the optical modulator, the electrodes comprise copper, silver, gold, aluminum, graphene, titanium, indium, and combinations thereof, preferably copper. The electrodes may be embedded in the polymer substrate in the form of wires (e.g., microwires); for example, copper microwires.

[0175] A connector is used to apply an electromagnetic field to the electrodes, wherein the applied electromagnetic field causes nanoparticles and microparticles to move from a first electrode to a second electrode and from the second electrode to the first electrode. A connector for applying the electromagnetic field to the electrodes 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, 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 can be adapted to provide waveform power. At least one of amplitude, frequency, and phase can be adapted to provide different states in the optical modulator. For example, multiple aspects of the power supply can be adapted by a controller.

[0176] The optical modulator 10 may include one or more segments, each segment being a single optically switchable entity, the size of which may be variable. A substrate at least partially encloses a volume, which may be a segment.

[0177] This device may include driving circuitry that alters the appearance of a (individual) segment by applying an electromagnetic field. Therefore, the appearance of the light modulator and one or more of its components can also be altered. For example, the segment may have an area of ​​at least 1 mm². This design allows for stacking, thereby allowing for more colors; for example, for full-color applications, stacking two or three modulators can correspondingly provide most or all colors.

[0178] Having one or more segments allows the light modulator to be locally controlled; this is advantageous for some applications, but not essential. 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 locally controlled, such as blocking sunlight spots without reducing the overall transparency or reflectivity of the window. The segments can be relatively large, for example, having a diameter of at least 1 mm or at least 1 cm.

[0179] In one exemplary embodiment of the optical modulator, substrates (11, 12) are aligned, and / or electrodes (13, 14) are aligned. For example, electrodes 13a, 13b and electrodes 14a, 14b may be aligned opposite each other. In the aligned substrates, when viewed from a direction orthogonal to the substrates, the electrodes on the different substrates are behind each other. When the optical modulator is disassembled and both substrates are arranged with the electrodes facing upwards, the electrode patterns are mirror images of each other.

[0180] Aligning the substrates can increase the maximum transparency or maximum reflectivity of the optical modulator; on the other hand, when selecting an optical modulator for more criteria than just the transparency or reflectivity range, misalignment or incomplete alignment of the two substrates may be better. Optical modulators can be stacked. For example, two stacked optical modulators can be made from three substrates, with the middle substrate having electrodes on both of its surfaces. In one embodiment of the optical modulator, optionally at least one substrate 11, 12 of the first optical modulator is identical to substrate 11, 12 of at least one second optical modulator. For stacked modulators, alignment can also increase maximum transparency or maximum reflectivity, but may be detrimental to other considerations (e.g., diffraction).

[0181] Figure 9b An embodiment of one implementation of the optical modulator 40 is schematically shown. The optical modulator 40 is similar to the optical modulator 10, except that it includes multiple optical layers; in the embodiment shown, there are two optical layers. More than two optical layers may also be present. Each optical layer is disposed between two substrates. The optical modulator 40 can be considered as follows: Figure 9a The image shows a stacked optical modulator with two substrates. As shown, the optical modulator 40 includes three substrates: a first substrate 41, a second substrate 42, and a third substrate 43. An optical layer is located between substrates 41 and 42, and another optical layer is located between substrates 42 and 43. These optical layers may be similar to those in the optical modulator 10. A controller 46 is configured to control the current on the electrodes of the substrates. For example, in… Figure 9b In this configuration, the controller 46 can be electrically connected to at least (4 times 2 equals) 8 electrodes.

[0182] Interestingly, the particles in multiple optical layers can be different, allowing multiple layers to be used to control more optical properties of the light modulator. For example, particles in different optical layers can absorb or reflect different wavelengths, such as having different colors. This can be used to create different colors and / or different color intensities on the panel via controller 46. For example, a quad-substrate panel can have three optical layers, each with different color particles, such as cyan, yellow, and magenta. By controlling the transparency or reflectivity of different colors, a wide color spectrum can be created.

[0183] The surface of another substrate facing one substrate may be provided with two or more patterns, as in one embodiment. For example, outer substrates 41 and 43 may receive electrodes only on the inner side, while the inner substrate (e.g., substrate 42) may have electrodes on both sides.

[0184] Substrate 41 and substrate 42 can be considered together as one embodiment of an optical modulator. Similarly, substrate 42 and substrate 43 can be considered together as one embodiment of an optical modulator.

[0185] Figure 9c An embodiment of one implementation of a car 20 with a smart glass window 21 is schematically shown. This is a particularly advantageous implementation because the level of incident light changes frequently and rapidly during driving. An advantage of using smart glass in a car is that the light level can be maintained at a constant level by adjusting the transparency of the window. In a car, faster and / or more uniform transitions between optical states (e.g., a faster transition to opacity) are particularly advantageous because they reduce driver distraction during transitions. The car 20 may include a controller configured to control the transparency or reflectivity of the window 21.

[0186] Smart glass can also be used in other glass applications, especially where the amount of incident light is variable, such as in buildings, offices, homes, greenhouses, and skylights. Skylights are windows installed in the ceiling to allow sunlight into a room.

[0187] The optical 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 optical modulator (e.g., optical modulator 10 or optical modulator 40) may be configured as follows:

[0188] - Switching to a second optical state, such as a non-transparent or non-reflective state, is achieved by: creating an alternating voltage on at least one of the first and second substrates; applying an alternating current between at least one first electrode and one second electrode on the first substrate; and / or applying an alternating current between the first electrode and one second electrode on the second substrate.

[0189] - Switching to a first optical state, such as a transparent state or a reflective state, is achieved by: creating an alternating voltage between a first substrate and a second substrate; applying an alternating current between a first electrode on the first substrate and a first electrode on the second substrate; and / or applying an alternating current between a second electrode on the first substrate and a second electrode on the second substrate.

[0190] The electrode pattern on the first substrate is arranged in at least part of the same pattern as the second electrode on the second substrate. Typically, the electrodes are opposite each other, but the patterns of the first electrode and the second electrode may also be offset relative to each other.

[0191] The protective coating may be applied to at least a portion of the inner surface region of at least one of the first substrate and the second substrate.

[0192] The drive signal applied to the drive electrodes typically has a varying voltage. For example, an AC frequency power supply can be used to switch between a transparent and a non-transparent state. This signal can have a frequency between, for example, 1 Hz and 1000 Hz. A balanced electrolytic current can be obtained by continuously switching the charged electrodes of relative polarity on the first substrate and the second substrate, and / or continuously switching the charged electrodes of relative polarity between the first substrate and the second substrate.

[0193] In one embodiment, a method for controlling an electrophoretic optical modulator driven by asymmetric electrodes includes:

[0194] - An alternating current signal is applied to multiple electrodes to create an electric field between them, thereby providing electrophoretic motion of particles toward or from one of the electrodes, resulting in modulation of the optical properties of the light modulator.

[0195] - The amplitude of an alternating current signal applied to multiple electrodes on a substrate is modulated to cause a low-field region (in which the electric field is reduced) to move relative to the electrodes. For example, Figure 10 An embodiment of a method 400 for controlling an electrophoretic optical modulator with asymmetric electrode drive is schematically illustrated. Method 400 includes:

[0196] Receive (410) command to increase or decrease panel transparency,

[0197] Depending on the received command, select a set of AC signals (420).

[0198] The relative amplitudes in this set of AC signals are periodically changed (430).

[0199] The signal is applied (440) to the electrodes in the panel.

[0200] As will be apparent to those skilled in the art, many different ways are possible to perform a method according to one embodiment. For example, the steps may be performed in the order shown, but the order of the steps may be changed, or some steps may be performed in parallel. Furthermore, other method steps may be inserted between the steps. The inserted steps may represent a refinement of the method as described herein, or may be unrelated to the method. For example, steps 430 and 440 may be performed at least partially in parallel. Moreover, a given step may not be fully completed before the next step begins.

[0201] Implementations of the method may be executed using software, which includes instructions for causing a processor system to execute method 400. The software may include only those steps taken by a specific sub-entity of the system. The software may be stored on a suitable storage medium (e.g., hard disk, floppy disk, memory, optical disk, etc.). The software may be transmitted as a signal wired or wirelessly or using a data network (e.g., the Internet). The software may be available for download and / or remote use on a server. Implementations of the method may be executed using a bitstream arranged to configure programmable logic (e.g., a field-programmable gate array (FPGA)) to execute the method.

[0202] It will be understood that the invention also extends to computer programs suitable for implementing the invention, particularly computer programs on or in a carrier. The program may be source code, object code, intermediate source code, and object code in the form of partially compiled code, or any other form suitable for implementing one embodiment of the method. One embodiment relating to a computer program product includes computer-executable instructions corresponding to each processing step of at least one of the elaborated methods. These instructions may be subdivided into subroutines and / or stored in one or more files that may be statically or dynamically linked. Another embodiment relating to a computer program product includes computer-executable instructions corresponding to each device of at least one of the elaborated systems and / or products.

[0203] Figure 11aA computer-readable medium 1000 having a writable portion 1010 and a computer-readable medium 1001 also having a writable portion are shown. The computer-readable medium 1000 is shown in the form of an optically readable medium. The computer-readable medium 1001 is shown in the form of an electronic memory, in this example, a memory card. Both computer-readable media 1000 and 1001 can store data 1020, wherein the data can indicate instructions that, when executed by a processor system, cause the processor system to perform a method according to one embodiment. The computer program 1020 may be included on the computer-readable medium 1000 as a physical marker or by magnetization of the computer-readable medium 1000. However, any other suitable embodiments are contemplated. Furthermore, it will be understood that although the computer-readable medium 1000 is shown herein as an optical disc, the computer-readable medium 1000 can be any suitable computer-readable medium, such as a hard disk, solid-state storage, flash memory, etc., and can be non-recordable or recordable. The computer program 1020 includes instructions for causing the processor system to perform the method of electrophoretic control.

[0204] Figure 11b A schematic representation of a processor system 1140 according to one embodiment is shown. The processor system includes one or more integrated circuits 1110. Figure 11b The diagram schematically illustrates the architecture of one or more integrated circuits 1110. Integrated circuit 1110 includes a processing unit 1120 (e.g., a CPU) for running computer program components to perform a method according to one embodiment and / or a module or unit implementing it. Integrated circuit 1110 includes a memory 1122 for storing programming code, data, etc. A portion of the memory 1122 may be read-only. Integrated circuit 1110 may include a communication element 1126, such as an antenna, a connector, or both or the like. Integrated circuit 1110 may include an application-specific integrated circuit 1124 for performing some or all of the processing defined in the method. Processing unit 1120, memory 1122, application-specific integrated circuit 1124, and communication element 1126 may be interconnected to each other via interconnects 1130 (e.g., a bus). Integrated circuit 1110 may be arranged for contact communication and / or contactless communication, using an antenna and / or a connector, respectively.

[0205] For example, in one embodiment, the processor system 1140 (e.g., an electrophoresis controller or an optical modulator) may include processor circuitry and memory circuitry, the processor being configured to execute software stored in the memory circuitry. For example, the processor circuitry may be an Intel Core i7 processor, an ARM Cortex-R8, etc. In one embodiment, the processor circuitry may be an ARM Cortex M0. The memory circuitry may be ROM circuitry or non-volatile memory (e.g., flash memory). The memory circuitry may be volatile memory, such as SRAM memory. In the latter case, the device may include a non-volatile software interface (e.g., a hard disk, a network interface, etc.) configured to provide the software.

[0206] It should be noted that the embodiments mentioned above are illustrative and not limiting of the invention, and those skilled in the art will be able to devise many alternative embodiments.

[0207] In the claims, any reference numerals enclosed in parentheses shall not be construed as limiting the claims. The use of the verb "comprise" and its variations does not exclude the presence of elements or steps other than those recited in the claims. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. When an expression such as "at least one" precedes a list of elements, it indicates the selection of all elements or any subset thereof from the list. For example, the expression "at least one of A, B, and C" should be understood to include only A, only B, only C, both A and B, both A and C, both B and C, or all of A, B, and C. The invention can be implemented by means of hardware comprising several different elements, as well as by means of a suitably programmed computer. In the means claims enumerating several parts, several of these means may be implemented by the same item of hardware. The mere fact that certain measures are recited in different dependent claims does not indicate that a combination of these measures cannot be used to exert an advantage.

[0208] In the claims, the marks enclosed in parentheses refer to reference symbols in the figures of exemplary embodiments or formulas of embodiments, thereby improving the comprehensibility of the claims. These marks should not be construed as limiting the claims.

Claims

1. An electrophoretic optical modulator with asymmetric electrode drive, the optical modulator comprising: At least a first substrate and a second substrate, wherein the second substrate is arranged opposite to the first substrate; An optical layer is disposed between the first substrate and the second substrate, the optical layer comprising a fluid, the fluid comprising particles, the particles being charged or capable of being charged; Multiple interdigitated electrodes are arranged across each of the first substrate and the second substrate; And a controller configured to apply an alternating current signal to the plurality of electrodes to obtain an electric field between the plurality of electrodes, thereby providing electrophoretic motion of particles toward one of the plurality of electrodes, or providing electrophoretic motion of particles from one of the plurality of electrodes, to cause modulation of the optical properties of the light modulator, wherein The controller is configured to modulate the amplitude of the alternating current signals applied to the plurality of electrodes on the substrate, and the asymmetric electrode drive includes applying different amplitude signals to at least some electrodes in the optical modulator. in: - Modulate the amplitude to cause a low electric field region to move relative to the electrode, wherein the low electric field region is a region where the particle movement is stationary relative to the electrode, or - Modulate the amplitude to cause a low electric field region to move relative to the electrode, wherein the electric field strength in the low electric field region of the optical layer is 25% or less of the maximum electric field strength in the optical layer.

2. The optical modulator of claim 1, wherein the controller is configured for a shutdown operation of the optical modulator, and the low electric field region moves between two opposing electrodes on opposing substrates.

3. The optical modulator of claim 1, wherein the controller is configured for an on operation of the optical modulator, wherein the low electric field region moves parallel to the substrate.

4. The optical modulator according to any one of claims 1 to 3, wherein the amplitude is modulated until a target gray level is reached, after which the controller applies an electrical sustaining signal to the plurality of electrodes on the substrate to maintain the gray level of the optical modulator.

5. The optical modulator according to any one of claims 1 to 3, wherein the first AC signal applied to the first electrode is scaled relative to the second AC signal applied to the second electrode.

6. The optical modulator according to any one of claims 1 to 3, wherein scaling between two AC signals applied to the two electrodes cycles between a lower scaling factor and a higher scaling factor.

7. The optical modulator of claim 6, wherein the first AC signal has a constant amplitude, and the second AC signal is scaled relative to the first AC signal.

8. The optical modulator of claim 1, wherein the scaling between two AC signals applied to the two electrodes is modulated to randomize the position of the low electric field region.

9. The optical modulator according to any one of claims 1 to 3, wherein the controller is configured to: - Shutdown operation, wherein the amplitude ratio of a pair of signals applied to a pair of opposing electrodes on opposing substrates changes, and / or - Open operation, in which the amplitude ratio of a pair of signals applied to a pair of adjacent electrodes on the same substrate changes.

10. The optical modulator according to any one of claims 1 to 3, wherein a first AC signal applied to a first electrode is scaled relative to a second AC signal applied to a second electrode, wherein the lower amplitude of the first AC signal and the second AC signal is at most 70%, 50%, 45%, 40%, or 30% of the higher amplitude.

11. The optical modulator according to any one of claims 1 to 3, wherein at least one of the AC signals has a high-frequency component and a low-frequency component, the high-frequency component having a frequency of at least 500 Hz or 750 Hz, and the low-frequency component having a frequency of at most 100 Hz.

12. The optical modulator of claim 11, wherein the high-frequency component has a frequency of at least 1 kHz.

13. The optical modulator of claim 11, wherein the high-frequency component is removed when the target gray level is reached.

14. The optical modulator of claim 11, wherein a low-pass filter is applied to the AC signal.

15. The optical modulator of claim 11, wherein the particles in the fluid are moved by electrophoretic forces and dielectric forces.

16. The optical modulator according to any one of claims 1 to 3, wherein the first substrate includes a first electrode and an adjacent second electrode, and the second substrate includes a third electrode and an adjacent fourth electrode, the first electrode and the fourth electrode being opposite to each other, and the second electrode and the third electrode being opposite to each other, the controller being configured to use a first phase for the first electrode, an increased phase for the second electrode, another increased phase for the third electrode, and yet another increased phase for the fourth electrode.

17. The electrophoretic optical modulator of claim 1, wherein the low electric field region is a dead zone in which no electric field exists, and the controller is configured to move the dead zone relative to the electrode.

18. The electrophoretic optical modulator according to claim 1, wherein: - Compared to the maximum electric field in the optical layer, the electric field strength in the low electric field region of the optical layer is 15% or less, 10% or less, or 1% or less; or - The electric field strength in the low electric field region of the optical layer is less than 2. 10^6 V / m, less than 1 10^6 V / m, or less than 1 10^5 V / m; or - The electric field strength in the low electric field region is up to 15% or up to 10% greater than the minimum electric field strength in the optical layer.

19. A controller configured to control an asymmetric AC signal of an electrophoretic optical modulator, the optical modulator comprising: At least a first substrate and a second substrate, wherein the second substrate is arranged opposite to the first substrate; An optical layer is disposed between the first substrate and the second substrate, the optical layer comprising a fluid, the fluid comprising particles, the particles being charged or capable of being charged; Multiple interdigitated electrodes are arranged across each of the first substrate and the second substrate; The controller is configured to apply an alternating current signal to the plurality of electrodes to obtain an electric field between the plurality of electrodes, thereby providing electrophoretic motion of particles toward one of the plurality of electrodes, or providing electrophoretic motion of particles from one of the plurality of electrodes, to cause modulation of the optical properties of the optical modulator, wherein the controller is configured to modulate the amplitude of the alternating current signal applied to the plurality of electrodes on the substrate. in: - Modulate the amplitude to cause a low electric field region to move relative to the electrode, wherein the low electric field region is a region where the particle movement is stationary relative to the electrode, or - Modulate the amplitude to cause a low electric field region to move relative to the electrode, wherein the electric field strength in the low electric field region of the optical layer is 25% or less of the maximum electric field strength in the optical layer.

20. A method for controlling an electrophoretic optical modulator driven by asymmetric electrodes, the optical modulator comprising: At least a first substrate and a second substrate, wherein the second substrate is arranged opposite to the first substrate; An optical layer is disposed between the first substrate and the second substrate, the optical layer comprising a fluid, the fluid comprising particles, the particles being charged or capable of being charged; The method includes: a plurality of interdigitated electrodes arranged across each of the first substrate and the second substrate; and the plurality of interdigitated electrodes being arranged across each of the second substrate. - This causes an alternating current signal to be applied to the plurality of electrodes to obtain an electric field between the plurality of electrodes, thereby providing electrophoretic motion of particles toward one of the plurality of electrodes, or providing electrophoretic motion of particles from one of the plurality of electrodes, to cause modulation of the optical properties of the light modulator. - The amplitude of the alternating current signal applied to the plurality of electrodes on the substrate is modulated, wherein: - Modulate the amplitude to cause a low electric field region to move relative to the electrode, wherein the low electric field region is a region where the particle movement is stationary relative to the electrode, or - Modulate the amplitude to cause a low electric field region to move relative to the electrode, wherein the electric field strength in the low electric field region of the optical layer is 25% or less of the maximum electric field strength in the optical layer.

21. A temporary or non-temporary computer-readable medium (1000) comprising data (1020) representing instructions that, when executed by a processor system, cause the processor system to perform the method according to claim 20.

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