Patent Application
20170075103
This disclosure relates to an electromechanical systems device, and more particularly to an electromechanical systems device including two or more electrically isolated electrode segments each connected to a distinct thin film transistor.
Electromechanical systems (EMS) include devices having electrical and mechanical elements, actuators, transducers, sensors, optical components such as mirrors and optical films, and electronics. EMS devices or elements can be manufactured at a variety of scales including, but not limited to, microscales and nanoscales. For example, microelectromechanical systems (MEMS) devices can include structures having sizes ranging from about a micron to hundreds of microns or more. Nanoelectromechanical systems (NEMS) devices can include structures having sizes smaller than a micron including, for example, sizes smaller than several hundred nanometers. Electromechanical elements may be created using deposition, etching, lithography, and/or other micromachining processes that etch away parts of substrates and/or deposited material layers, or that add layers to form electrical and electromechanical devices.
One type of EMS device is called an interferometric modulator (IMOD). The term IMOD or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In some implementations, an IMOD display element may include a pair of conductive plates, one or both of which may be transparent and/or reflective, wholly or in part, and capable of relative motion upon application of an appropriate electrical signal. For example, one plate may include a stationary layer deposited over, on or supported by a substrate and the other plate may include a reflective membrane separated from the stationary layer by an air gap. The position of one plate in relation to another can change the optical interference of light incident on the IMOD display element. IMOD-based display devices have a wide range of applications, and are anticipated to be used in improving existing products and creating new products, especially those with display capabilities.
Many EMS and MEMS devices apply a voltage to generate an electrostatic attraction between two electrodes to cause one electrode to move in relation to the other electrode. The positions of one or both of the electrodes can become unstable as the electrostatic force between the electrodes increases quadratically with decreasing distance between the electrodes. For example, after a movable electrode travels a certain distance, the movable electrode can quickly travel the remaining separation distance, which is a phenomenon referred to as “snap-through.” In addition, tilt can occur if the movable electrode has any asymmetry or experiences any degree of asymmetric perturbation, and charge can build up in the area of the tilt that can serve as a positively reinforcing mechanism, which results in tilt instability. Beyond a certain critical travel range, tilting can become unstable and one side or corner of the EMS or MEMS device can snap down.
The systems, methods, and devices of this disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.
One innovative aspect of the subject matter described in this disclosure can be implemented in an EMS device. The EMS device includes a substrate, a stationary electrode over the substrate, a movable electrode over the stationary electrode with a gap between the movable electrode and the stationary electrode, and a plurality of thin film transistors (TFTs). At least one of the stationary electrode and the movable electrode includes a plurality of electrically isolated electrode segments. Each of the TFTs are connected to and correspond to a distinct one of the plurality of electrode segments, the plurality of TFTs configured to drive the movable electrode to two or more positions across the gap by a common voltage.
In some implementations, the plurality of electrically isolated electrode segments include four or more electrically isolated electrode segments. In some implementations, the plurality of TFTs are configured to maintain a fixed charge in the plurality of electrically isolated electrode segments when the movable electrode is driven across the gap. In some implementations, the EMS device further includes a gate line electrically coupled to the plurality of TFTs, wherein each of the plurality of TFTs share the gate line, and a data line electrically coupled to the plurality of TFTs, wherein each of the plurality of TFTs share the data line. In some implementations, the EMS device further includes a plurality of hinges connected to the movable electrode, wherein at least one of the hinges includes the gate line and at least one of the hinges includes the data line.
Another innovative aspect of the subject matter described in this disclosure can be implemented in an EMS device. The EMS device includes a substrate, a stationary electrode over the substrate, a movable electrode over the stationary electrode with a gap between the movable electrode and the stationary electrode, and means for maintaining a fixed charge in the electrically isolating means when the movable electrode is driven across the gap. At least one of the stationary electrode and the movable electrode includes means for electrically isolating into electrode segments, and the means for maintaining the fixed charge are connected to the electrically isolating means and configured to drive the movable electrode across the gap by a common voltage.
In some implementations, the maintaining the fixed charge means include a plurality of thin film transistors (TFTs), each of the plurality of TFTs connected to and corresponding to a distinct one of the electrode segments. In some implementations, the EMS device further includes a gate line electrically coupled to the plurality of TFTs, wherein each of the plurality of TFTs share the gate line, and a data line electrically coupled to the plurality of TFTs, wherein each of the plurality of TFTs share the data line. In some implementations, the electrically isolating means includes four or more electrically isolated electrode segments each separated by dielectric material.
Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of manufacturing an EMS device. The method includes providing a first substrate, forming a plurality of TFTs on the first substrate, forming a plurality of electrically isolated electrode segments over the TFTs where each of the TFTs connect to and correspond to a distinct one of the plurality of electrode segments, and forming a movable electrode over the electrode segments and separated by a gap therebetween. The movable electrode is supported by a plurality of hinges connected to the movable electrode, where the plurality of TFTs are configured to drive the movable electrode to two or more positions across the gap by a common voltage.
In some implementations, the method further includes forming a dielectric layer between the TFTs and the electrode segments, the dielectric layer electrically isolating the electrode segments from one another, and forming a plurality of vias extending through the dielectric layer to connect the plurality of TFTs to the plurality of electrode segments. IN some implementations, the plurality of electrically isolated electrode segments include four or more electrically isolated electrode segments. In some implementations, the method further includes providing a second substrate opposite the first substrate, wherein the plurality of hinges are formed on the second substrate for supporting the movable electrode.
Another innovative aspect of the subject matter described in this disclosure can be implemented in a method of manufacturing an EMS device. The method includes providing a substrate, forming a stationary electrode on the substrate, forming a plurality of electrically isolated electrode segments in a movable layer where the movable layer and the stationary electrode are separated by a gap therebetween, and forming a plurality of TFTs over the electrode segments in the movable layer. Each of the TFTs are connected to and correspond to a distinct one of the plurality of electrode segments, where the movable layer is supported by a plurality of hinges connected to the movable layer, and where the plurality of TFTs are configured to drive the movable layer to two or more positions across the gap by a common voltage.
In some implementations, the method further includes forming the plurality of hinges on the substrate for supporting the movable layer, where at least one of the hinges includes a gate line and wherein at least one of the hinges includes a data line. In some implementations, the method further includes forming a dielectric layer between the TFTs and the electrode segments, the dielectric layer electrically isolating the electrode segments from one another, and forming a plurality of vias extending through the dielectric layer to connect the plurality of TFTs to the plurality of electrode segments.
Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Although the examples provided in this disclosure are primarily described in terms of EMS and MEMS-based displays the concepts provided herein may apply to other types of displays such as liquid crystal displays (LCDs), organic light-emitting diode (“OLED”) displays, and field emission displays. Other features, aspects, and advantages will become apparent from the description, the drawings and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.
Like reference numbers and designations in the various drawings indicate like elements.
The following description is directed to certain implementations for the purposes of describing the innovative aspects of this disclosure. However, a person having ordinary skill in the art will readily recognize that the teachings herein can be applied in a multitude of different ways. The described implementations may be implemented in any device, apparatus, or system that can be configured to display an image, whether in motion (such as video) or stationary (such as still images), and whether textual, graphical or pictorial. More particularly, it is contemplated that the described implementations may be included in or associated with a variety of electronic devices such as, but not limited to: mobile telephones, multimedia Internet enabled cellular telephones, mobile television receivers, wireless devices, smartphones, Bluetooth® devices, personal data assistants (PDAs), wireless electronic mail receivers, hand-held or portable computers, netbooks, notebooks, smartbooks, tablets, printers, copiers, scanners, facsimile devices, global positioning system (GPS) receivers/navigators, cameras, digital media players (such as MP3 players), camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, electronic reading devices (e.g., e-readers), computer monitors, auto displays (including odometer and speedometer displays, etc.), cockpit controls and/or displays, camera view displays (such as the display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, microwaves, refrigerators, stereo systems, cassette recorders or players, DVD players, CD players, VCRs, radios, portable memory chips, washers, dryers, washer/dryers, parking meters, packaging (such as in electromechanical systems (EMS) applications including microelectromechanical systems (MEMS) applications, as well as non-EMS applications), aesthetic structures (such as display of images on a piece of jewelry or clothing) and a variety of EMS devices. The teachings herein also can be used in non-display applications such as, but not limited to, electronic switching devices, radio frequency filters, sensors, accelerometers, gyroscopes, motion-sensing devices, magnetometers, inertial components for consumer electronics, parts of consumer electronics products, varactors, liquid crystal devices, electrophoretic devices, drive schemes, manufacturing processes and electronic test equipment. Thus, the teachings are not intended to be limited to the implementations depicted solely in the Figures, but instead have wide applicability as will be readily apparent to one having ordinary skill in the art.
Some implementations described herein relate to an EMS device including a movable electrode and a stationary electrode separated by a gap therebetween. One of the electrodes is divided into two or more electrically isolated electrode segments, where each of the electrode segments connects to and corresponds to a distinct one of a plurality of TFTs. The plurality of TFTs are configured to drive the movable electrode to two or more positions across the gap towards the stationary electrode by application of a common voltage. The common voltage can be applied initially to move the movable electrode, and then the TFTs can isolate the electrodes so that a voltage for each electrode segment will independently vary depending on the position of the movable electrode. The plurality of TFTs combined with the isolated electrode segments can maintain a fixed charge in each of the electrode segments, which can reduce the effects of tilt instability. In some implementations, the EMS device includes a plurality of hinges connected to the movable electrode for supporting the movable electrode over the stationary electrode, where the plurality of hinges may be symmetrically arranged around the movable electrode. In some implementations, the EMS device can be a two-terminal EMS device. In some implementations, each of the TFTs can include a gate electrode connected to a gate line and a source/drain electrode connected to a data line, where each of the TFTs share the same gate line and data line.
Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. An EMS device with two-terminals is less complex to manufacture than an EMS device with three or more terminals, because the two-terminal EMS device may be manufactured without a top plate or multiple sacrificial layers. Also, the two-terminal EMS device can experience fewer complications in operation than an EMS device with three or more terminals. For example, a two-terminal EMS device can have a simpler drive scheme, simpler electronics, and simpler routing. In addition, a stationary or movable electrode with isolated electrode segments each connected to a distinct TFT prevents charge from moving that would lead to rotational instability in a movable electrode. A positively reinforcing mechanism caused by tilt instability is reduced by preventing charge from migrating to electrode segments with smaller gap sizes. Thus, as the gap size gets smaller for any electrode segment, the capacitance increases which then decreases the voltages, thereby decreasing the electrostatic pressure. Thus, the stable travel range of the EMS device is increased, adding greater precision and functionality to the EMS device without substantial reduction in total electrode area. In implementations where the EMS device is an IMOD, extending the stable travel range can extend the range of colors that can be reflected by the IMOD.
An example of a suitable EMS or MEMS device or apparatus, to which the described implementations may apply, is a reflective display device. Reflective display devices can incorporate interferometric modulator (IMOD) display elements that can be implemented to selectively absorb and/or reflect light incident thereon using principles of optical interference. IMOD display elements can include a partial optical absorber, a reflector (a.k.a. a mirror) that is movable with respect to the absorber, and an optical resonant cavity defined between the absorber and the reflector. In some implementations, the reflector can be moved to two or more different positions, which can change the size of the optical resonant cavity and thereby affect the reflectance of the IMOD. The reflectance spectra of IMOD display elements can create fairly broad spectral bands that can be shifted across the visible wavelengths to generate different colors. The position of the spectral band can be adjusted by changing the thickness of the optical resonant cavity. One way of changing the optical resonant cavity is by changing the position of the reflector with respect to the absorber. However, if the reflector is tilted, the thickness of the optical resonant cavity becomes uneven, causing the color to become off in part of the IMOD. Thus, it is important to provide a reflector that is reflector that is resistant to tilt. By adopting at least some of the features disclosed herein, the reflector of the IMOD can be more resistant to tilting.
The IMOD display device can include an array of IMOD display elements which may be arranged in rows and columns. Each display element in the array can include at least a pair of reflective and semi-reflective layers, such as a movable reflective layer (i.e., a movable layer, also referred to as a mechanical layer) and a fixed partially reflective layer (i.e., a stationary layer), positioned at a variable and controllable distance from each other to form an air gap (also referred to as an optical gap, cavity or optical resonant cavity). The movable reflective layer may be moved between at least two positions. For example, in a first position, i.e., a relaxed position, the movable reflective layer can be positioned at a distance from the fixed partially reflective layer. In a second position, i.e., an actuated position, the movable reflective layer can be positioned more closely to the partially reflective layer. Incident light that reflects from the two layers can interfere constructively and/or destructively depending on the position of the movable reflective layer and the wavelength(s) of the incident light, producing either an overall reflective or non-reflective state for each display element. In some implementations, the display element may be in a reflective state when unactuated, reflecting light within the visible spectrum, and may be in a dark state when actuated, absorbing and/or destructively interfering light within the visible range. In some other implementations, however, an IMOD display element may be in a dark state when unactuated, and in a reflective state when actuated. In some implementations, the introduction of an applied voltage can drive the display elements to change states. In some other implementations, an applied charge can drive the display elements to change states.
The depicted portion of the array in
In
The optical stack 16 can include a single layer or several layers. The layer(s) can include one or more of an electrode layer, a partially reflective and partially transmissive layer, and a transparent dielectric layer. In some implementations, the optical stack 16 is electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more of the above layers onto a transparent substrate 20. The electrode layer can be formed from a variety of materials, such as various metals, for example indium tin oxide (ITO). The partially reflective layer can be formed from a variety of materials that are partially reflective, such as various metals (e.g., chromium and/or molybdenum), semiconductors, and dielectrics. The partially reflective layer can be formed of one or more layers of materials, and each of the layers can be formed of a single material or a combination of materials. In some implementations, certain portions of the optical stack 16 can include a single semi-transparent thickness of metal or semiconductor which serves as both a partial optical absorber and electrical conductor, while different, electrically more conductive layers or portions (e.g., of the optical stack 16 or of other structures of the display element) can serve to bus signals between IMOD display elements. The optical stack 16 also can include one or more insulating or dielectric layers covering one or more conductive layers or an electrically conductive/partially absorptive layer.
In some implementations, at least some of the layer(s) of the optical stack 16 can be patterned into parallel strips, and may form row electrodes in a display device as described further below. As will be understood by one having ordinary skill in the art, the term “patterned” is used herein to refer to masking as well as etching processes. In some implementations, a highly conductive and reflective material, such as aluminum (Al), may be used for the movable reflective layer 14, and these strips may form column electrodes in a display device. The movable reflective layer 14 may be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes of the optical stack 16) to form columns deposited on top of supports, such as the illustrated posts 18, and an intervening sacrificial material located between the posts 18. When the sacrificial material is etched away, a defined gap 19, or optical cavity, can be formed between the movable reflective layer 14 and the optical stack 16. In some implementations, the spacing between posts 18 may be approximately 1-1000 μm, while the gap 19 may be approximately less than 10,000 Angstroms (Å).
In some implementations, each IMOD display element, whether in the actuated or relaxed state, can be considered as a capacitor formed by the fixed and moving reflective layers. When no voltage is applied, the movable reflective layer 14 remains in a mechanically relaxed state, as illustrated by the display element 12 on the left in
The processor 21 can be configured to communicate with an array driver 22. The array driver 22 can include a row driver circuit 24 and a column driver circuit 26 that provide signals to, for example a display array or panel 30. The cross section of the IMOD display device illustrated in
The details of the structure of IMOD displays and display elements may vary widely.
As illustrated in
Aspects of the implementations show in
In implementations such as those shown in
For many EMS and MEMS devices, a voltage can be applied to generate an electrostatic attraction between two electrodes of the device. The electrostatic force between the two electrodes is inversely proportional to separation distance between the two electrodes, and can increase quadratically as the separation distance decreases. As a movable electrode is driven towards a stationary electrode, the movable electrode can become unstable after the movable electrode travels a certain distance, and the movable electrode can travel the remaining separation distance without any additional stimulus or perturbation. This phenomenon can be referred to as “snap-through.”
Moreover, if the movable electrode tilts by even the slightest degree, which can be caused by any asymmetry in the movable electrode or the slightest asymmetric perturbation, charge can build up in the area of the tilt and lead to a positively reinforcing mechanism. This mechanism contributes to tilt instability of the movable electrode. Thus, the range of stable travel positions through which the movable electrode can be electrostatically displaced can be limited at least in part by a tendency of the movable electrode to tilt. The tendency to tilt can result from any asymmetry in the EMS device, such as variances or imperfections in the manufacture of the EMS device. A slight rotational instability can lead to unintended “snap-through” or collapse of an electrostatically displaced movable electrode towards the stationary electrode when the movable electrode is near the edge of a stable range of positions. This can be due, in part, to imbalanced charge accumulation on the movable electrode which leads to tilting and subsequent collapse of the movable electrode. Therefore, beyond a certain critical travel range or tilt angle, the tilting becomes unstable and one side or corner of the device can collapse or snap-through. For example, after the movable electrode travels at least half of the distance between two electrodes, the tilting can become unstable in the EMS device. The distance between two electrodes, such as the movable electrode and the stationary electrode, can be referred to as an “electrical gap.” An issue like tilt instability can limit the range of stable positions of EMS devices, which limits the performance of the EMS device.
Some EMS devices may include optical devices, such as IMODs, as discussed earlier herein. By way of an example, an IMOD can have a stable range from an initial electrical gap at about 540 nm (e.g., green) to about 360 nm (e.g., red). Hence, the IMOD can tune continuously within the red-green-blue (RGB) color spectrum from about 360 nm to about 540 nm. In another example, an IMOD can have a stable range from an initial electrical gap at about 350 nm (e.g., blue), to about 250 nm (e.g., red), and to about 170 nm (e.g., green). Hence, the IMOD can tune continuously within the RGB color spectrum from about 350 nm to about 170 nm. It will be understood that the standard range of positions for color generation may vary depending on the design of the IMOD. Beyond the stable range of positions, tuning the IMOD to generate various wavelengths of light, such as black may be difficult. Even if some IMODs try to extend the stable region in the electrical gap by driving with charge instead of voltage, or adding a capacitor in series, such configurations of IMODs can still be subject to tilt instability.
IMODs 12 of
In implementations where the two-terminal EMS device 400 is an IMOD, as the movable electrode 414 is moved towards the stationary electrode 416, the height of the gap 419 between the movable electrode 414 and the stationary electrode 416 will change, and a color reflected by the IMOD will vary. An IMOD driven in a multi-state manner can therefore provide a particular color in response to application of a particular voltage. However, the limited stable range Rs1 can place constraints on the range of possible colors for the IMOD. To provide an increased stable range, some IMODs may include three terminals, but a three-terminal EMS device may introduce complications with multiple electrodes and may be more costly to manufacture than a two-terminal EMS device.
In some implementations of the two-terminal EMS device 400, the stable range Rs1 can be one-third of the maximum height h1. Beyond one-third of the maximum height h1, the movable electrode 414 may snap-through the remainder of the gap 419. In some implementations, the stable range Rs1 can be increased, such as by incorporating a series capacitor in the two-terminal EMS device 400. However, the stable range Rs1 can still be limited by the effects of tilt instability. In some implementations, for example, the stable range Rs1 can be one-half of the maximum height h1 before the two-terminal EMS device 400 experiences tilt instability. Hence, the stable range Rs1 can be effectively limited by the effects of snap-through and tilt instability.
As used herein, reference to terms such as “stationary electrode” and “movable electrode” can refer to structures including one or more layers or sublayers. In some implementations, a stationary electrode can include multiple layers, such as one or more of an electrically conductive layer, a partially absorbing layer, and a transparent dielectric layer, an example of which is shown in the optical stack 16 of
A voltage source (not shown) can apply a voltage to the two-terminal EMS device 500 between the movable electrode 514 and the stationary electrode 516, which creates an electrostatic force on the movable electrode 514 to move the movable electrode 514 to two or more positions across the gap 519 towards the stationary electrode 516. As illustrated in
In some implementations, the electrode segments 516a and 516b can be symmetrical to each other. In some implementations, the electrode segments 516a and 516b can be symmetrical along one or more axes defining the plane of the electrode 516. The axes can be perpendicular to each other and can define axes of rotation of the movable electrode 514. For example, the stationary electrode 516 can be divided into four electrically isolated electrode segments. Four electrode segments, when divided evenly along an x-axis and y-axis, can be provide greater stability in the two-terminal EMS device 500 so that one or more electrode segments may not be more subject to tilt along the x-axis or the y-axis than the other electrode segments. Electrode segments 516a and 516b can be identical in electrode area and symmetric about the center of the stationary electrode 516. Generally, having the electrode segments 516a and 516b identical in electrode area and symmetrical can be more effective in increasing the stable range of the two-terminal EMS device 500 than not having electrode segments 516a and 516b that are identical and symmetrical. That way, one electrode segment is not more prone to tilt than the other. Nonetheless, it will be understood that the electrode segments 516a and 516b need not be identical or symmetrical. In such implementations, the stable range of the two-terminal EMS device 500 can still be increased. Also, it will be understood that the two-terminal EMS device 500 is not limited to dividing the stationary electrode 516, but can alternatively have the movable electrode 514 divided into two or more electrically isolated electrode segments.
The two-terminal EMS device 500 can have a stable range Rs2 so that application of a voltage less than an actuation voltage of the two-terminal EMS device 500 can cause the movable electrode 514 to move within the stable range Rs2. The stable range Rs2 can constitute the range of stable positions between a maximum height h2 and a minimum stability height hs2. If the applied voltage is equal to or exceeds the actuation voltage of the two-terminal EMS device 500, the movable electrode 514 will collapse against the stationary electrode 516.
The electrode segments 516a and 516b can be electrically isolated by a dielectric layer 515. In some implementations, the dielectric layer 515 can surround the electrode segments 516a and 516b in the stationary electrode 516, where the dielectric layer 515 can be disposed on the substrate 520. In some implementations, the dielectric layer 515 can have a thickness equal to or greater than a thickness of the electrode segments 516a and 516b. Where the thickness of the dielectric layer 515 exceeds a thickness of the electrode segments 516a and 516b, the stable range Rs2 may be increased because the electrical gap between the electrodes 514 and 516 is greater than the maximum gap height h2.
Typically, when a movable electrode includes electrically isolated electrode segments, a stable range of an EMS device can be increased. When the movable electrode begins to tilt, the amount of charge that shifts to the outer edges of the electrode segments is less than if the movable electrode included a single, undivided electrode. For example, if the movable electrode were separated into four electrode segments, the amount of charge that would shift to the outer edges of the electrode segment closest to the stationary electrode could be on the order of half the charge that would shift to the outer edge of single, undivided electrode. However, the amount of charge that could shift to the outer edge can vary in different implementations. Nonetheless, the division of charge accumulation can occur because the charge on the more distant electrode segment not tilted towards the undivided stationary electrode cannot move across the dielectric material separating the electrode segments. By inhibiting charge accumulation in such a manner in the movable electrode, the movable electrode can be more tilt-resistant and can increase the stable range of the EMS device. In some implementations, one electrode can include an undivided electrode, such as a driving electrode, and a plurality of electrode segments, where the plurality of electrode segments are separated from one another and separated from the undivided electrode. For example, a movable electrode can include a driving electrode over two or more electrode segments, where dielectric material separates the driving electrode from the two or more electrode segments, and where the two or more electrode segments are electrically isolated from one another. A more detailed description of an example EMS device with segmented electrodes in a movable layer is provided in U.S. patent application Ser. No. 13/804,261 to Chan et al., filed Mar. 14, 2013 and entitled “Electromechanical Systems Device with Segmented Electrodes,” the entirety of which is incorporated by reference herein for all purposes.
The segmented electrodes as described above may be electrically isolated and “floating.” In other words, such segmented electrodes may be disposed between a driving electrode and a stationary electrode without any electrical connections. This effectively creates a capacitor in series that can extend the stable range of the electrical gap.
In
C=Q/V.
Pressure (p), or electrostatic force between two electrodes per unit area, is proportional to the voltage or potential difference:
P=F/A=−∈V
2/2z2.
Accordingly, when a portion of the movable electrode 514 tilts, voltage decreases between the two electrodes 514 and 516, which can lead to a less negative (more positive) pressure between the two electrodes 514 and 516 during actuation.
In
In some implementations, the mechanism for driving the two-terminal EMS device 500 can be achieved by a plurality of TFTs (not shown), where each of the TFTs can be connected to and corresponding to a distinct one of the electrically isolated electrode segments 516a and 516b. The TFTs can be configured to maintain constant charge in each of the electrically isolated electrode segments 516a and 516b. Even though the stationary electrode 516 is segmented, the plurality of TFTs can apply a common voltage to drive the movable electrode 514 to two or more positions across the gap 519. The TFTs apply a common voltage, and then provide isolation between the electrodes 514 and 516 after the voltage is applied and the movable electrode 514 begins to move. A common voltage may be associated with a single or common signal provided to the plurality of TFTs. In some implementations, the plurality of TFTs may share a common source for providing the common voltage, such as a shared gate line and/or shared data line, as discussed in more detail below. When electrode segments 516a and 516b are connected to TFTs to drive the two-terminal EMS device 500 and maintain a constant charge in each of the electrode segments 516a and 516b, the stable range Rs2 in
The two-terminal EMS device 600 can further include a gate line 652 electrically coupled to the plurality of TFTs 636a, 636b, 636c, and 636d, and a data line 654 electrically coupled to the plurality of TFTs 636a, 636b, 636c, and 636d. Each of the plurality of TFTs 636a, 636b, 636c, and 636d share the gate line 652 and share the data line 654. Hence, rather than each of the TFTs 636a, 636b, 636c, and 636d applying a separate signal/voltage to each of the quadrants 616a, 616b, 616c, and 616d, the plurality of TFTs 636a, 636b, 636c, and 636d apply a common voltage to the quadrants 616a, 616b, 616c, and 616d. The common voltage can come from a signal provided by either of the gate line 652 or the data line 654. In other words, the gate line 652 or the data line 654 is configured to provide a signal associated with the common voltage. That way, different signals or voltages are not used to drive the quadrants 616a, 616b, 616c, and 616d of the first electrode 616. The common voltage is applied through the plurality of TFTs 636a, 636b, 636c, and 636d to drive the second electrode 614 towards the first electrode 616. The common voltage that is applied through the plurality of TFTs 636a, 636b, 636c, and 636d can be applied for a short duration, which can be shorter than the time it takes for second electrode 614 to substantially move. Thus, the voltage is common to the quadrants 616a, 616b, 616c, and 616d while the TFTs 636a, 636b, 636c, and 636d are connecting the electrodes 614 and 616. The TFTs 636a, 636b, 636c, and 636d may be considered “on” when the common voltage is applied. When the second electrode 614 is moving towards the first electrode 616, the TFTs 636a, 636b, 636c, and 636d may be disconnected or considered “off” Then the voltage for each quadrant 616a, 616b, 616c, and 616d will vary depending on the position of the second electrode 614, which determines its capacitance. Since each quadrant 616a, 616b, 616c, and 616d is independent when the TFTs 636a, 636b, 636c, and 636d are disconnected, each quadrant 616a, 616b, 616c, and 616d can have its own voltage. When tilting is prevented, the voltages for the quadrants 616a, 616b, 616c, and 616d are equal to one another.
The plurality of TFTs 636a, 636b, 636c, and 636d can maintain a constant charge in each of the quadrants 616a, 616b, 616c, and 616d, where the quadrants 616a, 616b, 616c, and 616d are electrically isolated from one another and can prevent charge from migrating to other quadrants 616a, 616b, 616c, and 616d with smaller gap sizes. The plurality of TFTs 636a, 636b, 636c, and 636d can be configured to maintain a fixed charge in each of the quadrants 616a, 616b, 616c, and 616d when the second electrode 614 is driven across the gap between the two electrodes 614 and 616. In some implementations, the gate line 652 can be in electrical communication with a row driver circuit 24 for providing a signal to a display array or panel 30 in
In some implementations, each of the TFTs 636a, 636b, 636c, and 636d can include a gate electrode, a semiconductor layer, and a source/drain electrode. The gate electrode, the semiconductor layer, and the source/drain electrode of the TFT can be arranged according to any suitable TFT design known in the art, such as top-gate or bottom-gate TFTs, planar TFT or staggered TFT, amorphous silicon TFTs or low-temperature polysilicon TFTs, etc. In some implementations, the gate electrode can be configured to receive a first signal from the gate line 652 associated with the common voltage. In some implementations, the source/drain electrode can be configured to receive a second signal from the data line 654 associated with the common voltage. The source/drain electrode may be patterned so that a source electrode corresponds to a source region in the semiconductor layer and a drain electrode corresponds to drain region in the semiconductor layer. The semiconductor layer can include a channel region between the source region and the drain region. In some implementations, the semiconductor layer can be an active layer that includes a metal oxide semiconducting material, such as indium-gallium-zinc-oxide.
As illustrated in
z(x,y)=z(0,0)+(−x sin θ+y cos θ)Φ.
A tilt axis (rotation axis) can lie in the x-y plane of the second electrode 614 along an angle θ. Torque (T) is a measure of the applied force multiplied by a distance to the tilt axis. Tilt stability can be measured by the change in torque over the change in tilt angle defined by the following equation:
dT/dΦ=∫∫dp/dΦ(−x sin θ+y cos θ)dxdy.
The stable condition occurs where dT/dΦ<0.
As mentioned above, any asymmetry in the two-terminal EMS device 600 or any slight asymmetric perturbation can lead to rotational instability of the second electrode 614, leading to a positively reinforcing mechanism so that the second electrode 614 becomes increasingly imbalanced during actuation. Hence, if one side tilts down slightly, the force on that side increases, and the tilt increases even more. The positively reinforcing mechanism produces a positive value for dT/dΦ. Thus, introducing a negative value for dT/dΦ into the design or operation of the two-terminal EMS device 600 can provide a restoring force that limits the effect of tilt instability, thereby increasing the stable range of the two-terminal EMS device 600.
Vertical position (z) changes as a function of tilt angle Φ and potential difference V changes as a function of tilt angle Φ. The tilt stability of the two-terminal EMS device 600 can be determined by two terms:
dT
e1
/dΦ=∫∫(dp/dz)(dz/dΦ)(−x sin θ+y cos θ)dxdy,
dT
e2
/dΦ=∫∫(dp/dV)(dV/dΦ)(−x sin θ+y cos θ)dxdy.
The first term is a positive value. If one side tilts down, then electrostatic attraction between the two electrodes 614 and 616 increases, and then the force on that side increases so that it tends to tilt more. Pressure increases as vertical position decreases, and vertical position decreases as tilt angle increases. After integration, the overall sign is positive. Thus, this first term may be referred to as a “positive feedback” term. For a square plate with each side having a length L, the first term can be:
dT
e1
/dΦ=∈V
2
L
4/12z3.
The second term can be a negative value. Capacitance increases as one side tilts down. The increased capacitance can cause the voltage to decrease. Additionally, the voltage can decrease with increased capacitance when charge is held constant. Voltage decreases as tilt angle increases, and pressure decreases as voltage decreases. After integration, the overall sign is negative. Therefore, this second term may be referred to as a “negative feedback” term. How negative the negative feedback term is can depend on the voltage potential between the two electrodes 614 and 616. After introducing a common voltage between two electrodes 614 and 616, the multiple TFTs can be disconnected or turned off so that each quadrant 616a, 616b, 616c, and 616d can take on its own voltage and maintain a constant charge across each quadrant 616a, 616b, 616c, and 616d. This can lead to a reduced electrostatic pressure in particular quadrants 616a, 616b, 616c, and 616d that can provide a more negative feedback term to counteract against the positive feedback term caused by tilt instability. For a square plate with each side having a length L and where charge is constant, the second term can be:
dT
e2
/dΦ=−∈V
2
L
4/16z3.
In some implementations, the tilt stability of the two-terminal EMS device 600 can be determined by one or more additional terms. For example, hinges 634a, 634b, 634c, and 634d can connect to the edges of the second electrode 614 as shown in
dT/dΦ=−kΣ(z−zo)2.
Where the hinges 634a, 634b, 634c, and 634d are connected at the edges of the second electrode 614, the term can be negative and determined to be:
dT/dΦ=−kL
2/2.
By way of another example, hinges 634a, 634b, 634c, and 634d may connect to the corners of the second electrode 614 as shown in
dT/dΦ=−kL
2.
A tilt stable condition can be calculated for the two-terminal EMS device 600 with edge connections in
−kL2/2+∈V2L4/12z3−∈V2L4/16z3<0,
which can be simplified to z>(1/4)zo. A tilt stable condition can be calculated for the two-terminal EMS device 600 with corner connections in
−kL2+∈V2L4/12z3−∈V2L4/16z3<0,
which can be simplified to z>(1/7)zo. Thus, the two-terminal EMS device 600 can have an increased stable range, where the two-terminal EMS device 600 is stable at all positions up to ¼ of the initial launch position zo for edge connections in
The stationary electrode 716 can include two or more electrically isolated electrode segments 716a and 716b. The electrode segments 716a and 716b may be separated by dielectric material so that each of the electrode segments 716a and 716b are electrically isolated from one another, and charge cannot flow across from one electrode segment to another. The size or amount of dielectric material between the electrode segments 716a and 716b can be relatively small, such as a thickness of a few microns or less, or a thickness of less than about one micron depending on the process tolerance. That way, an appreciable reduction in total electrode area of the stationary electrode 716 can be avoided or at least minimized. In some implementations, the electrode segments 716a and 716b can be symmetrical to one another. In some implementations, the stationary electrode 716 can be divided into four or more electrode segments, where the four or more electrode segments can constitute quadrants in a square plate as illustrated in the implementation in
The EMS device 700 can further include two or more TFTs 736a and 736b, where each of the TFTs 736a and 736b connect to and correspond to a distinct one of the electrode segments 716a and 716b. Each of the TFTs 736a and 736b may be disposed over the substrate 720, where the TFTs 736a and 736b may be formed simultaneously. As shown in
Like the EMS device 700 in
As illustrated in the example in
The EMS device 900 includes a movable electrode 914 having two or more electrically isolated electrode segments 914a and 914b, where the electrode segments 914a and 914b may be separated by dielectric material. The EMS device 900 can further include two or more TFTs 936a and 936b, where TFT 936a is electrically connected to electrode segment 914a by via 940a, and TFT 936b is electrically connected to electrode segment 914b by via 940b. Each of the TFTs 936a and 936b may be formed over the electrode segments 914a and 914b, where the TFTs 936a and 936b may be formed simultaneously. Each of the TFTs 936a and 936b can include a gate electrode 942 connected to a shared gate line, and each of the TFTs 936a and 936b can include a source/drain electrode 944 connected to a shared data line. In some implementations, a semiconductor layer can be disposed between the gate electrode 942 and the source/drain electrode 944. For example, the semiconductor layer can include a metal oxide semiconducting material, such as indium-gallium-zinc-oxide. The TFTs 936a and 936b can be configured to drive the movable electrode 914 to two or more positions across the gap 919 by a common voltage. The common voltage can be applied from either a gate line or a data line providing a signal to the TFTs 936a and 936b, where the common voltage produces an electrostatic force for driving the movable electrode 914 towards the stationary electrode 916. Application of the common voltage from the electrode segments 914a and 914b via TFTs 936a and 936b that maintain constant charge can reduce the effects of tilt instability. In some implementations, the movable electrode 914 may refer to a movable layer or movable structure including the electrode segments 914a and 914b as well as the TFTs 936a and 936b.
In some implementations, the EMS device 900 can further include a first hinge 952 and a second hinge 954 for supporting the movable electrode 914. In
As illustrated in
It will be understood that the segmented movable electrode or segmented stationary electrode described above is not limited to a number of segments, but can include any suitable number of segments. Also, the segmented movable electrode or segmented stationary electrode can include any suitable shape, such as square, rectangular, circular, etc.
At block 1110, a first substrate is provided. In some implementations, the first substrate can include any suitable substrate material, such as a semiconducting material, glass, or plastic as discussed earlier herein.
At block 1120, a plurality of TFTs is formed on the first substrate. The number of TFTs formed on the first substrate may correspond to the number of electrode segments to be subsequently formed in the EMS device. Each of the TFTs may be formed simultaneously, where each of the layers of the TFTs may be deposited and patterned at the same time. In some implementations, for example, forming a TFT may include forming a gate electrode, forming a semiconductor layer over the gate electrode, and forming a source/drain electrode over the semiconductor layer. However, it will be understood that the TFT may have other TFT designs, including top gate and bottom gate TFTs, planar and staggered TFTs, etc. In some implementations, a gate line for the EMS device may connect to the gate electrode, and a data line for the EMS device may connect to the source/drain electrode. In some implementations, a first dielectric layer may be deposited over the plurality of TFTs.
At block 1130, a plurality of electrically isolated electrode segments are formed over the TFTs, each of the TFTs connected to and corresponding to a distinct one of the plurality of electrode segments. The first dielectric layer may be formed between the plurality of TFTs and the plurality of electrode segments. In some implementations, forming the electrode segments can include depositing an electrically conductive layer over the first dielectric layer and over the plurality of TFTs, and patterning the electrically conductive layer into electrode segments. In some implementations, the electrode segments can be symmetrical to one another. The electrically conductive layer can include a reflective metallic material, such as aluminum or aluminum alloy. In some implementations, a second dielectric layer may be deposited over the electrode segments and between the segments to electrically isolate the electrode segments. In some implementations, the plurality of electrically isolated electrode segments include four or more electrically isolated electrode segments. In some implementations, a plurality of vias can be formed extending through the first dielectric layer to connect the plurality of TFTs to the plurality of electrode segments.
At block 1140, a movable electrode is formed over the electrode segments and separated by a gap therebetween, where the movable electrode is supported by a plurality of hinges connected to the movable electrode, the plurality of TFTs configured to drive the movable electrode to two or more positions across the gap by a common voltage. The common voltage may be associated with signals provided by the gate line or the data line. After the TFTs apply the common voltage, the TFTs may provide isolation between the movable electrode and the electrode segments during actuation. That way, voltages may vary for each electrode segment depending on its gap size between the electrode segment and the movable electrode. The plurality of TFTs can be configured to maintain a fixed charge in each of the electrode segments when the movable electrode is driven across the gap. In some implementations, the movable electrode can include an absorber and the electrode segments can include a mirror or mirror segments. The hinges may be symmetrically arranged about the center of the movable electrode. In some implementations, the plurality of hinges may be formed on the second dielectric layer over the first substrate.
In some implementations, a second substrate may be provided opposite the first substrate, where the plurality of hinges are formed on the second substrate for supporting the movable electrode. The second substrate may include any substantially transparent material, such as glass. Glass substrates (sometimes referred to as glass plates or panels) may be or include a borosilicate glass, a soda lime glass, photoglass, quartz, Pyrex or other suitable glass material. Where the EMS device is a display device, an image for a display can be provided through the second substrate. In some implementations, spacers may be provided between the first substrate and the second substrate to define a maximum height of the gap between the movable electrode and the electrode segments. Thus, the TFTs may be formed on the first substrate while the movable electrode and hinges may be separately formed on the second substrate.
At block 1210, a substrate is provided. The first substrate can include any suitable substrate material, such as a semiconducting material, glass, or plastic. In some implementations, the substrate may include any substantially transparent material. Where the device is a display device, an image for a display can be provided through the substrate.
At block 1220, a stationary electrode is formed over the substrate. In some implementations, the stationary electrode includes an absorber. For example, the absorber can include molychrome or other suitable material configured to at least partially absorb light. In some implementations, a plurality of hinges are formed on the substrate for supporting a movable layer over the stationary electrode, where at least one of the hinges include a gate line and where at least one of the hinges include a data line.
At block 1230, a plurality of electrically isolated electrode segments are formed in the movable layer, where the movable layer and the stationary electrode are separated by a gap therebetween. A movable layer can be formed over the stationary electrode. In some implementations, the movable layer can be formed on a sacrificial layer between the stationary electrode and the movable layer, where subsequent removal of the sacrificial layer can release the EMS device. To form the movable layer, an electrically conductive layer can be deposited over the sacrificial layer and patterned into the electrode segments. In some implementations, the electrode segments can be symmetrical to one another. In some implementations, the plurality of electrode segments can include four or more electrode segments. In some implementations, a dielectric layer can be formed over the electrode segments and between the electrode segments, where the dielectric layer electrically isolates the electrode segments from one another.
At block 1240, a plurality of TFTs are formed over the electrode segments in the movable layer, each of the TFTs connected to and corresponding to a distinct one of the plurality of electrode segments, where the movable layer is supported by a plurality of hinges connected to the movable layer, the plurality of TFTs configured to drive the movable layer to two or more positions across the gap by a common voltage. After the TFTs apply the common voltage, the TFTs may provide isolation between the movable layer and the stationary electrode during actuation. That way, voltages may vary for each electrode segment depending on its gap size between the electrode segment and the stationary electrode. The plurality of TFTs can be configured to maintain a fixed charge in each of the electrode segments when the movable layer is driven across the gap. In forming the dielectric layer over the electrode segments, the dielectric layer may be formed between the TFTs and the electrode segments. In some implementations, a plurality of vias are formed extending through the dielectric layer to connect the plurality of TFTs to the plurality of electrode segments.
Each of the TFTs may be formed simultaneously, where each of the layers of the TFTs may be deposited and patterned at the same time. The number of TFTs formed on the dielectric layer may correspond to the number of electrode segments. In some implementations, for example, forming a TFT may include forming a source/drain electrode, forming a semiconductor layer over the source/drain electrode, and forming a gate electrode over the semiconductor layer. However, it will be understood that the TFT may have other TFT architectures, including top gate and bottom gate TFTs, planar and staggered TFTs, etc. In some implementations, at least one of the hinges including the gate line may connect to the gate electrode, and at least one of the hinges including the data line may connect to the source/drain electrode.
The display device 40 includes a housing 41, a display 30, an antenna 43, a speaker 45, an input device 48 and a microphone 46. The housing 41 can be formed from any of a variety of manufacturing processes, including injection molding, and vacuum forming. In addition, the housing 41 may be made from any of a variety of materials, including, but not limited to: plastic, metal, glass, rubber and ceramic, or a combination thereof. The housing 41 can include removable portions (not shown) that may be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols.
The display 30 may be any of a variety of displays, including a bi-stable or analog display, as described herein. The display 30 also can be configured to include a flat-panel display, such as plasma, EL, OLED, STN LCD, or TFT LCD, or a non-flat-panel display, such as a CRT or other tube device. In addition, the display 30 can include an IMOD-based display, as described herein.
The components of the display device 40 are schematically illustrated in
The network interface 27 includes the antenna 43 and the transceiver 47 so that the display device 40 can communicate with one or more devices over a network. The network interface 27 also may have some processing capabilities to relieve, for example, data processing requirements of the processor 21. The antenna 43 can transmit and receive signals. In some implementations, the antenna 43 transmits and receives RF signals according to the IEEE 16.11 standard, including IEEE 16.11(a), (b), or (g), or the IEEE 802.11 standard, including IEEE 802.11a, b, g, n, and further implementations thereof. In some other implementations, the antenna 43 transmits and receives RF signals according to the Bluetooth® standard. In the case of a cellular telephone, the antenna 43 can be designed to receive code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), Global System for Mobile communications (GSM), GSM/General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), Terrestrial Trunked Radio (TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized (EV-DO), 1×EV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access (HSPA), High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), Evolved High Speed Packet Access (HSPA+), Long Term Evolution (LTE), AMPS, or other known signals that are used to communicate within a wireless network, such as a system utilizing 3G, 4G or 5G technology. The transceiver 47 can pre-process the signals received from the antenna 43 so that they may be received by and further manipulated by the processor 21. The transceiver 47 also can process signals received from the processor 21 so that they may be transmitted from the display device 40 via the antenna 43.
In some implementations, the transceiver 47 can be replaced by a receiver. In addition, in some implementations, the network interface 27 can be replaced by an image source, which can store or generate image data to be sent to the processor 21. The processor 21 can control the overall operation of the display device 40. The processor 21 receives data, such as compressed image data from the network interface 27 or an image source, and processes the data into raw image data or into a format that can be readily processed into raw image data. The processor 21 can send the processed data to the driver controller 29 or to the frame buffer 28 for storage. Raw data typically refers to the information that identifies the image characteristics at each location within an image. For example, such image characteristics can include color, saturation and gray-scale level.
The processor 21 can include a microcontroller, CPU, or logic unit to control operation of the display device 40. The conditioning hardware 52 may include amplifiers and filters for transmitting signals to the speaker 45, and for receiving signals from the microphone 46. The conditioning hardware 52 may be discrete components within the display device 40, or may be incorporated within the processor 21 or other components.
The driver controller 29 can take the raw image data generated by the processor 21 either directly from the processor 21 or from the frame buffer 28 and can re-format the raw image data appropriately for high speed transmission to the array driver 22. In some implementations, the driver controller 29 can re-format the raw image data into a data flow having a raster-like format, such that it has a time order suitable for scanning across the display array 30. Then the driver controller 29 sends the formatted information to the array driver 22. Although a driver controller 29, such as an LCD controller, is often associated with the system processor 21 as a stand-alone Integrated Circuit (IC), such controllers may be implemented in many ways. For example, controllers may be embedded in the processor 21 as hardware, embedded in the processor 21 as software, or fully integrated in hardware with the array driver 22.
The array driver 22 can receive the formatted information from the driver controller 29 and can re-format the video data into a parallel set of waveforms that are applied many times per second to the hundreds, and sometimes thousands (or more), of leads coming from the display's x-y matrix of display elements.
In some implementations, the driver controller 29, the array driver 22, and the display array 30 are appropriate for any of the types of displays described herein. For example, the driver controller 29 can be a conventional display controller or a bi-stable display controller (such as an IMOD display element controller). Additionally, the array driver 22 can be a conventional driver or a bi-stable display driver (such as an IMOD display element driver). Moreover, the display array 30 can be a conventional display array or a bi-stable display array (such as a display including an array of IMOD display elements). In some implementations, the driver controller 29 can be integrated with the array driver 22. Such an implementation can be useful in highly integrated systems, for example, mobile phones, portable-electronic devices, watches or small-area displays.
In some implementations, the input device 48 can be configured to allow, for example, a user to control the operation of the display device 40. The input device 48 can include a keypad, such as a QWERTY keyboard or a telephone keypad, a button, a switch, a rocker, a touch-sensitive screen, a touch-sensitive screen integrated with the display array 30, or a pressure- or heat-sensitive membrane. The microphone 46 can be configured as an input device for the display device 40. In some implementations, voice commands through the microphone 46 can be used for controlling operations of the display device 40.
The power supply 50 can include a variety of energy storage devices. For example, the power supply 50 can be a rechargeable battery, such as a nickel-cadmium battery or a lithium-ion battery. In implementations using a rechargeable battery, the rechargeable battery may be chargeable using power coming from, for example, a wall socket or a photovoltaic device or array. Alternatively, the rechargeable battery can be wirelessly chargeable. The power supply 50 also can be a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell or solar-cell paint. The power supply 50 also can be configured to receive power from a wall outlet.
In some implementations, control programmability resides in the driver controller 29 which can be located in several places in the electronic display system. In some other implementations, control programmability resides in the array driver 22. The above-described optimization may be implemented in any number of hardware and/or software components and in various configurations.
As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.
The various illustrative logics, logical blocks, modules, circuits and algorithm steps described in connection with the implementations disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. The interchangeability of hardware and software has been described generally, in terms of functionality, and illustrated in the various illustrative components, blocks, modules, circuits and steps described above. Whether such functionality is implemented in hardware or software depends upon the particular application and design constraints imposed on the overall system.
The hardware and data processing apparatus used to implement the various illustrative logics, logical blocks, modules and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose single- or multi-chip processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, or, any conventional processor, controller, microcontroller, or state machine. A processor also may be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. In some implementations, particular steps and methods may be performed by circuitry that is specific to a given function.
In one or more aspects, the functions described may be implemented in hardware, digital electronic circuitry, computer software, firmware, including the structures disclosed in this specification and their structural equivalents thereof, or in any combination thereof. Implementations of the subject matter described in this specification also can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on a computer storage media for execution by, or to control the operation of, data processing apparatus.
Various modifications to the implementations described in this disclosure may be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the spirit or scope of this disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but are to be accorded the widest scope consistent with this disclosure, the principles and the novel features disclosed herein. Additionally, a person having ordinary skill in the art will readily appreciate, the terms “upper” and “lower” are sometimes used for ease of describing the figures, and indicate relative positions corresponding to the orientation of the figure on a properly oriented page, and may not reflect the proper orientation of, e.g., an IMOD display element as implemented.
Certain features that are described in this specification in the context of separate implementations also can be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation also can be implemented in multiple implementations separately or in any suitable subcombination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a subcombination or variation of a subcombination.
Similarly, while operations are depicted in the drawings in a particular order, a person having ordinary skill in the art will readily recognize that such operations need not be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Further, the drawings may schematically depict one more example processes in the form of a flow diagram. However, other operations that are not depicted can be incorporated in the example processes that are schematically illustrated. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the illustrated operations. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products. Additionally, other implementations are within the scope of the following claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve desirable results.
