Patent Publication Number: US-9898974-B2

Title: Display drive scheme without reset

Description:
TECHNICAL FIELD 
     This disclosure relates to electromechanical systems and devices. More specifically, this disclosure relates to a display drive scheme without a reset. 
     DESCRIPTION OF THE RELATED TECHNOLOGY 
     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. 
     One plate, or movable element of the IMOD display element, can move from an initial position associated with a first color to a second, new position such that the IMOD display element provides a second, new color. Transitioning directly from the initial position to the second position may introduce errors such that the position of the plate is at a slightly incorrect position rather than the expected second position. More errors may be introduced and accumulated when the position of the plate is to move from the second position to a third position. Accordingly, rather than transitioning directly from the initial position to the second position, an intermediate reset position may first be transitioned to in order to reduce the accumulation of errors, followed by transitioning from the intermediate reset position to the second position. Afterwards, the plate may be positioned back to the reset position and then repositioned to the third position. As such, using the intermediate reset position may reduce accumulated errors. 
     However, moving the plate to the reset position before moving to the new position may introduce visual artifacts, decrease color saturation, and require extra circuitry to provide the reset functionality. 
     SUMMARY 
     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 a circuit including a controller capable of determining a first voltage to apply to an electrode of a display unit of an array of display units to position a movable element of the display unit from a first position towards a second position, and the controller further capable of determining a second voltage to apply to the electrode of the display unit to position the movable element of the display unit at the second position. 
     In some implementations, the first voltage can correspond with a transition in color of the display unit, the first position corresponding with a first color, and the second position corresponding with a second color. 
     In some implementations, positioning the movable element of the display unit from the first position towards the second position can include moving the movable element into a range including the second position. 
     In some implementations, the second voltage can correspond with a voltage to position the movable element from a position in the range to the second position. 
     In some implementations, the controller can further be capable of determining a third voltage to apply to the electrode of the display unit to release the movable element of the display unit from hysteresis. 
     In some implementations, releasing the movable element of the display unit from hysteresis can include positioning the movable element to a position outside of a hysteresis region. 
     In some implementations, the circuit can include a frame buffer including data indicating a current color corresponding to the first position of the movable element of the display unit; and a storage device to store lookup tables (LUTs) indicating the first voltage and the second voltage. 
     In some implementations, the controller can determine the first voltage and the second voltage based on the data indicating the current color corresponding to the first position of the movable element, and image data indicating an intended color corresponding to the second position of the movable element. 
     In some implementations, the circuit can include a display including the array of display units; a processor that is capable of communicating with the display device, the processor being configured to process image data; and a memory device that is capable of communicating with the processor. 
     In some implementations, the circuit can include a driver circuit capable of sending at least one signal to the display; and wherein the controller is capable of sending at least a portion of the image data to the driver circuit. 
     In some implementations, the circuit can include an image source module capable of sending the image data to the processor, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter. 
     In some implementations, the circuit can include an input device capable of receiving input data and to communicate the input data to the processor. 
     Another innovative aspect of the subject matter described in this disclosure can be implemented in a system including a voltage data source indicating a first voltage corresponding with transitioning a display unit from providing a first color to a second color, and indicating a second voltage corresponding to the second color; and a driver circuit capable of providing the first voltage to an electrode of the display unit to position a movable element of the display unit from a first position associated with the first color towards a second position associated with the second color, and the driver circuit further capable of providing the second voltage to the electrode of the display unit to position the movable element of the display unit to the second position. 
     In some implementations, the driver circuit can be further capable of providing the first voltage to move the movable element into a range including the second position. 
     In some implementations, the second voltage can correspond with a voltage to position the movable element from a position in the range to the second position. 
     Another innovative aspect of the subject matter described in this disclosure can be implemented in a method including providing, by a driver circuit, a first voltage to an electrode of a display unit to position a movable element of the display unit from a first position towards a second position; and providing, by the driver circuit, a second voltage to the electrode of the display unit to position the movable element of the display unit to the second position. 
     In some implementations, the method can include providing, by the driver circuit, a third voltage to the electrode of the display unit to release the movable element of the display unit from hysteresis. 
     In some implementations, releasing the movable element of the display unit from hysteresis can include positioning the movable element to a position outside of a hysteresis region. 
     In some implementations, the first voltage can correspond with a transition in color of the display unit, the first position corresponding with a first color, and the second position corresponding with a second color. 
     In some implementations, positioning the movable element of the display unit from the first position towards the second position can include positioning the movable element in a range including the second position. 
     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, 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. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view illustration depicting two adjacent interferometric modulator (IMOD) display elements in a series or array of display elements of an IMOD display device. 
         FIG. 2  is a system block diagram illustrating an electronic device incorporating an IMOD-based display including a three element by three element array of IMOD display elements. 
         FIGS. 3A and 3B  are schematic exploded partial perspective views of a portion of an electromechanical systems (EMS) package including an array of EMS elements and a backplate. 
         FIG. 4  is an example of a system block diagram illustrating an electronic device incorporating an IMOD-based display. 
         FIG. 5  is a circuit schematic of an example of a three-terminal IMOD. 
         FIGS. 6A, 6B, and 6C  illustrate an example of accumulating positioning errors. 
         FIGS. 7A-E  illustrate an example positioning a movable element with an intermediate reset position. 
         FIGS. 8A, 8B, and 8C  illustrate an example of positioning a movable element without an intermediate reset position. 
         FIG. 9  is a flow diagram illustrating a method to position a movable element without an intermediate reset position. 
         FIGS. 10A, 10B and 10C  are charts illustrating an example of positioning a movable element in a hysteresis region. 
         FIGS. 11A-D  illustrate an example of positioning a movable element in a hysteresis region. 
         FIG. 12  is a flow diagram illustrating a method to position a movable element in a hysteresis region. 
         FIG. 13  is an example of a system block diagram for driving a display element. 
         FIGS. 14A, 14B, and 14C  illustrate an example of Lookup Tables (LUTs) for driving a display element. 
         FIGS. 15A, 15B, and 15C  illustrate another example of LUTs for driving a display element. 
         FIGS. 16A and 16B  are system block diagrams illustrating a display device that includes a plurality of IMOD display elements. 
     
    
    
     Like reference numbers and designations in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     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. 
     An interferometric modulator (IMOD) can include a movable element, such as a mirror, that may be positioned at various points (or locations) in order to reflect light at a specific wavelength at each specific point. For example, the movable element can be moved from an initial position associated with a first color (e.g., red) to a second position associated with a second color (e.g., blue). 
     In some implementations, the IMOD has three (3) terminals. The movable element may be positioned by applying voltages to the three terminals of the IMOD. However, moving directly from the initial position to the second position can be imprecise due to process variations, defects, noise, calibration issues, and/or other conditions affecting the voltages received by the terminals of the IMOD. For example, if the movable element should transition from a position corresponding to red to a position corresponding to blue, then 5 V may need to be applied to an electrode. However, the electrode may receive 4.98 V instead (due to the aforementioned conditions), and therefore, the movable element may be positioned at a slightly incorrect position rather than the expected position. As another example, while 5 V may be the usual, or expected, voltage normally applied for the transition, some electrodes associated with other movable elements may need a slightly different voltage, for example 4.98 V due to process variations (among movable elements) or errors from calibration. This may be problematic because the system may provide voltages to the electrodes of the IMOD based on the expected position of the mirror (i.e., the expected second position rather than the slightly incorrect position). If the movable element is at the incorrect position and the mirror is to move to a third position, the voltage applied to the electrode would be based on the movable element being at the second position rather than the incorrect position, and therefore, the movable element may be positioned to another incorrect position. These positioning errors may accumulate such that eventually the movable element&#39;s actual position drifts further and further away from the expected position. 
     A mechanical reset may be used to position the movable element to a reset position before moving to the second position. The reset position may be an intermediate position between moving the movable element from a first position to a second position. Since the movable element would always be moved to the reset position before moving to the second position, an accumulation of positioning errors can be avoided. However, a mechanical reset may need extra circuitry, decrease color saturation, and may generate visual artifacts. 
     Some implementations of the subject matter described herein provide for the positioning of the movable element without the mechanical reset. The movable element may move from a first position associated with a first color towards a second position associated with a second color and within a range of the second position by applying a voltage associated with a transition from the first color to the second color. Afterwards, a second voltage may be applied to stabilize the movable element within the range to the specific second position. 
     Particular implementations of the subject matter described in this disclosure can be implemented to realize one or more of the following potential advantages. Positioning the movable elements without moving to a reset position may allow for increased color saturation. Additionally, visual artifacts from moving to the reset position may be avoided. Moreover, dedicated reset circuitry may also be eliminated. 
     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 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. 
       FIG. 1  is an isometric view illustration depicting two adjacent interferometric modulator (IMOD) display elements in a series or array of display elements of an IMOD display device. The IMOD display device includes one or more interferometric EMS, such as MEMS, display elements. In these devices, the interferometric MEMS display elements can be configured in either a bright or dark state. In the bright (“relaxed,” “open” or “on,” etc.) state, the display element reflects a large portion of incident visible light. Conversely, in the dark (“actuated,” “closed” or “off,” etc.) state, the display element reflects little incident visible light. MEMS display elements can be configured to reflect predominantly at particular wavelengths of light allowing for a color display in addition to black and white. In some implementations, by using multiple display elements, different intensities of color primaries and shades of gray can be achieved. 
     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  FIG. 1  includes two adjacent interferometric MEMS display elements in the form of IMOD display elements  12 . In the display element  12  on the right (as illustrated), the movable reflective layer  14  is illustrated in an actuated position near, adjacent or touching the optical stack  16 . The voltage V bias  applied across the display element  12  on the right is sufficient to move and also maintain the movable reflective layer  14  in the actuated position. In the display element  12  on the left (as illustrated), a movable reflective layer  14  is illustrated in a relaxed position at a distance (which may be predetermined based on design parameters) from an optical stack  16 , which includes a partially reflective layer. The voltage V 0  applied across the display element  12  on the left is insufficient to cause actuation of the movable reflective layer  14  to an actuated position such as that of the display element  12  on the right. 
     In  FIG. 1 , the reflective properties of IMOD display elements  12  are generally illustrated with arrows indicating light  13  incident upon the IMOD display elements  12 , and light  15  reflecting from the display element  12  on the left. Most of the light  13  incident upon the display elements  12  may be transmitted through the transparent substrate  20 , toward the optical stack  16 . A portion of the light incident upon the optical stack  16  may be transmitted through the partially reflective layer of the optical stack  16 , and a portion will be reflected back through the transparent substrate  20 . The portion of light  13  that is transmitted through the optical stack  16  may be reflected from the movable reflective layer  14 , back toward (and through) the transparent substrate  20 . Interference (constructive and/or destructive) between the light reflected from the partially reflective layer of the optical stack  16  and the light reflected from the movable reflective layer  14  will determine in part the intensity of wavelength(s) of light  15  reflected from the display element  12  on the viewing or substrate side of the device. In some implementations, the transparent substrate  20  can be a glass substrate (sometimes referred to as a glass plate or panel). The glass substrate may be or include, for example, a borosilicate glass, a soda lime glass, quartz, Pyrex, or other suitable glass material. In some implementations, the glass substrate may have a thickness of 0.3, 0.5 or 0.7 millimeters, although in some implementations the glass substrate can be thicker (such as tens of millimeters) or thinner (such as less than 0.3 millimeters). In some implementations, a non-glass substrate can be used, such as a polycarbonate, acrylic, polyethylene terephthalate (PET) or polyether ether ketone (PEEK) substrate. In such an implementation, the non-glass substrate will likely have a thickness of less than 0.7 millimeters, although the substrate may be thicker depending on the design considerations. In some implementations, a non-transparent substrate, such as a metal foil or stainless steel-based substrate can be used. For example, a reverse-IMOD-based display, which includes a fixed reflective layer and a movable layer which is partially transmissive and partially reflective, may be configured to be viewed from the opposite side of a substrate as the display elements  12  of  FIG. 1  and may be supported by a non-transparent substrate. 
     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  FIG. 1 , with the gap  19  between the movable reflective layer  14  and optical stack  16 . However, when a potential difference, i.e., a voltage, is applied to at least one of a selected row and column, the capacitor formed at the intersection of the row and column electrodes at the corresponding display element becomes charged, and electrostatic forces pull the electrodes together. If the applied voltage exceeds a threshold, the movable reflective layer  14  can deform and move near or against the optical stack  16 . A dielectric layer (not shown) within the optical stack  16  may prevent shorting and control the separation distance between the layers  14  and  16 , as illustrated by the actuated display element  12  on the right in  FIG. 1 . The behavior can be the same regardless of the polarity of the applied potential difference. Though a series of display elements in an array may be referred to in some instances as “rows” or “columns,” a person having ordinary skill in the art will readily understand that referring to one direction as a “row” and another as a “column” is arbitrary. Restated, in some orientations, the rows can be considered columns, and the columns considered to be rows. In some implementations, the rows may be referred to as “common” lines and the columns may be referred to as “segment” lines, or vice versa. Furthermore, the display elements may be evenly arranged in orthogonal rows and columns (an “array”), or arranged in non-linear configurations, for example, having certain positional offsets with respect to one another (a “mosaic”). The terms “array” and “mosaic” may refer to either configuration. Thus, although the display is referred to as including an “array” or “mosaic,” the elements themselves need not be arranged orthogonally to one another, or disposed in an even distribution, in any instance, but may include arrangements having asymmetric shapes and unevenly distributed elements. 
       FIG. 2  is a system block diagram illustrating an electronic device incorporating an IMOD-based display including a three element by three element array of IMOD display elements. The electronic device includes a processor  21  that may be configured to execute one or more software modules. In addition to executing an operating system, the processor  21  may be configured to execute one or more software applications, including a web browser, a telephone application, an email program, or any other software application. 
     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  FIG. 1  is shown by the lines  1 - 1  in  FIG. 2 . Although  FIG. 2  illustrates a 3×3 array of IMOD display elements for the sake of clarity, the display array  30  may contain a very large number of IMOD display elements, and may have a different number of IMOD display elements in rows than in columns, and vice versa. 
     In some implementations, the packaging of an EMS component or device, such as an IMOD-based display, can include a backplate (alternatively referred to as a backplane, back glass or recessed glass) which can be configured to protect the EMS components from damage (such as from mechanical interference or potentially damaging substances). The backplate also can provide structural support for a wide range of components, including but not limited to driver circuitry, processors, memory, interconnect arrays, vapor barriers, product housing, and the like. In some implementations, the use of a backplate can facilitate integration of components and thereby reduce the volume, weight, and/or manufacturing costs of a portable electronic device. 
       FIGS. 3A and 3B  are schematic exploded partial perspective views of a portion of an EMS package  91  including an array  36  of EMS elements and a backplate  92 .  FIG. 3A  is shown with two corners of the backplate  92  cut away to better illustrate certain portions of the backplate  92 , while  FIG. 3B  is shown without the corners cut away. The EMS array  36  can include a substrate  20 , support posts  18 , and a movable layer  14 . In some implementations, the EMS array  36  can include an array of IMOD display elements with one or more optical stack portions  16  on a transparent substrate, and the movable layer  14  can be implemented as a movable reflective layer. 
     The backplate  92  can be essentially planar or can have at least one contoured surface (e.g., the backplate  92  can be formed with recesses and/or protrusions). The backplate  92  may be made of any suitable material, whether transparent or opaque, conductive or insulating. Suitable materials for the backplate  92  include, but are not limited to, glass, plastic, ceramics, polymers, laminates, metals, metal foils, Kovar and plated Kovar. 
     As shown in  FIGS. 3A and 3B , the backplate  92  can include one or more backplate components  94   a  and  94   b , which can be partially or wholly embedded in the backplate  92 . As can be seen in  FIG. 3A , backplate component  94   a  is embedded in the backplate  92 . As can be seen in  FIGS. 3A and 3B , backplate component  94   b  is disposed within a recess  93  formed in a surface of the backplate  92 . In some implementations, the backplate components  94   a  and/or  94   b  can protrude from a surface of the backplate  92 . Although backplate component  94   b  is disposed on the side of the backplate  92  facing the substrate  20 , in other implementations, the backplate components can be disposed on the opposite side of the backplate  92 . 
     The backplate components  94   a  and/or  94   b  can include one or more active or passive electrical components, such as transistors, capacitors, inductors, resistors, diodes, switches, and/or integrated circuits (ICs) such as a packaged, standard or discrete IC. Other examples of backplate components that can be used in various implementations include antennas, batteries, and sensors such as electrical, touch, optical, or chemical sensors, or thin-film deposited devices. 
     In some implementations, the backplate components  94   a  and/or  94   b  can be in electrical communication with portions of the EMS array  36 . Conductive structures such as traces, bumps, posts, or vias may be formed on one or both of the backplate  92  or the substrate  20  and may contact one another or other conductive components to form electrical connections between the EMS array  36  and the backplate components  94   a  and/or  94   b . For example,  FIG. 3B  includes one or more conductive vias  96  on the backplate  92  which can be aligned with electrical contacts  98  extending upward from the movable layers  14  within the EMS array  36 . In some implementations, the backplate  92  also can include one or more insulating layers that electrically insulate the backplate components  94   a  and/or  94   b  from other components of the EMS array  36 . In some implementations in which the backplate  92  is formed from vapor-permeable materials, an interior surface of backplate  92  can be coated with a vapor barrier (not shown). 
     The backplate components  94   a  and  94   b  can include one or more desiccants which act to absorb any moisture that may enter the EMS package  91 . In some implementations, a desiccant (or other moisture absorbing materials, such as a getter) may be provided separately from any other backplate components, for example as a sheet that is mounted to the backplate  92  (or in a recess formed therein) with adhesive. Alternatively, the desiccant may be integrated into the backplate  92 . In some other implementations, the desiccant may be applied directly or indirectly over other backplate components, for example by spray-coating, screen printing, or any other suitable method. 
     In some implementations, the EMS array  36  and/or the backplate  92  can include mechanical standoffs  97  to maintain a distance between the backplate components and the display elements and thereby prevent mechanical interference between those components. In the implementation illustrated in  FIGS. 3A and 3B , the mechanical standoffs  97  are formed as posts protruding from the backplate  92  in alignment with the support posts  18  of the EMS array  36 . Alternatively or in addition, mechanical standoffs, such as rails or posts, can be provided along the edges of the EMS package  91 . 
     Although not illustrated in  FIGS. 3A and 3B , a seal can be provided which partially or completely encircles the EMS array  36 . Together with the backplate  92  and the substrate  20 , the seal can form a protective cavity enclosing the EMS array  36 . The seal may be a semi-hermetic seal, such as a conventional epoxy-based adhesive. In some other implementations, the seal may be a hermetic seal, such as a thin film metal weld or a glass frit. In some other implementations, the seal may include polyisobutylene (PIB), polyurethane, liquid spin-on glass, solder, polymers, plastics, or other materials. In some implementations, a reinforced sealant can be used to form mechanical standoffs. 
     In alternate implementations, a seal ring may include an extension of either one or both of the backplate  92  or the substrate  20 . For example, the seal ring may include a mechanical extension (not shown) of the backplate  92 . In some implementations, the seal ring may include a separate member, such as an O-ring or other annular member. 
     In some implementations, the EMS array  36  and the backplate  92  are separately formed before being attached or coupled together. For example, the edge of the substrate  20  can be attached and sealed to the edge of the backplate  92  as discussed above. Alternatively, the EMS array  36  and the backplate  92  can be formed and joined together as the EMS package  91 . In some other implementations, the EMS package  91  can be fabricated in any other suitable manner, such as by forming components of the backplate  92  over the EMS array  36  by deposition. 
       FIG. 4  is an example of a system block diagram illustrating an electronic device incorporating an IMOD-based display.  FIG. 4  depicts an implementation of row driver circuit  24  and column driver circuit  26  of array driver  22  that provide signals to display array or panel  30 , as previously discussed. 
     The implementation of display module  710  in display array  30  may include a variety of different designs. As an example, display module  710  in the fourth row may include switch  720  and display unit  750 . Display module  710  may be provided a row signal, reset signal, bias signal, and a common signal from row driver circuit  24 . Display module  710  may also be provided a data, or column, signal from column driver circuit  26 . In some implementations, display unit  750  may be coupled with switch  720 , such as a transistor with its gate coupled to the row signal and its drain coupled with the column signal. Each display unit  750  may include an IMOD display element as a pixel. 
     Some IMODs are three-terminal devices that use a variety of signals.  FIG. 5  is a circuit schematic of an example of a three-terminal IMOD. In the example of  FIG. 5 , display module  710  includes display unit  750  (e.g., an IMOD). The circuit of  FIG. 5  also includes switch  720  of  FIG. 4  implemented as an n-type metal-oxide-semiconductor (NMOS) transistor T 1   810 . The gate of transistor T 1   810  is coupled to V row    830  (i.e., a control terminal of transistor T 1   810  is coupled to V row    830  providing a row select signal), which may be provided a voltage by row driver circuit  24  of  FIG. 4 . Transistor T 1   810  is also coupled to V column    820 , which may be provided a voltage by column driver circuit  26  of  FIG. 4 . If V row    830  (providing a row select signal) is biased to turn transistor T 1   810  on, the voltage on V column    820  may be applied to V d  electrode  860 . The circuit of  FIG. 5  also includes another switch implemented as an NMOS transistor T 2   815 . The gate (or control) of transistor T 2   815  is coupled with V reset    895 . The other two terminals of transistor T 2   815  are coupled with V com  electrode  865  and V d  electrode  860 . When transistor T 2   815  is biased to turn on (e.g., by a voltage of a reset signal on V reset    895  applied to the gate of transistor T 2   815 ), V com  electrode  865  and V d  electrode  860  may be shorted together. 
     Display unit  750  may be a three-terminal IMOD including three terminals or electrodes: V bias  electrode  855 , V d  electrode  860 , and V com  electrode  865 . Display unit  750  may also include movable element  870  and dielectric  875 . Movable element  870  may include a mirror, as previously discussed. Movable element  870  may be coupled with V d  electrode  860 . Additionally, air gap  890  may be between V bias  electrode  855  and V d  electrode  860 . Air gap  885  may be between V d  electrode  860  and V com  electrode  865 . In some implementations, display unit  750  may also include one or more capacitors. For example, one or more capacitors can be coupled between V d  electrode  860  and V com  electrode  865  and/or between V bias  electrode  855  and V d  electrode  860 . Other configurations of display unit  750  may include dielectric  875  or another dielectric being close to V com  electrode  865 . 
     Movable element  870  may be positioned at various points between V bias  electrode  855  and V com  electrode  865  to reflect light at a specific wavelength, and therefore, provide color. In particular, voltages applied to V bias  electrode  855 , V d  electrode  860 , and V com  electrode  865  may determine the position of movable element  870 . Voltages for V reset    895 , V column    820 , V row    830 , V com  electrode  865 , and V bias  electrode  855  may be provided by driver circuits such as row driver circuit  24  and column driver circuit  26 . In some implementations, V com  electrode  865  may be coupled to ground rather than driven by row driver circuit  24  or column driver circuit  26 . Accordingly, movable element  870  may be positioned between V bias  electrode  855  and V com  electrode  865  and the sizes of air gaps  885  and  890  may change based on the position of movable element  870 . 
     In some implementations, positioning movable element  870  may result in an accumulation of positioning errors that cause the actual position of movable element  870  to deviate from the expected position. For example, movable element  870  may be at a first position such that display unit  750  provides the color red. Display unit  750  may next need to provide the color blue. Therefore, the position of movable element  870  may need to change to a new, second position to provide the color blue. Accordingly, voltages may be applied to V com  electrode  865 , V d  electrode  860 , and V bias  electrode  855  such that movable element  870  may be positioned to the new, second position from the first position associated with the color red. Movable element  870  may then be positioned from the second position to a third position to provide another color. 
     However, positioning movable element  870  directly from the first position to the second position may result in a positioning error. In particular, due to process variations, defects, noise, calibration errors, and other conditions, the voltages applied to an electrode may deviate from the expected voltage. As an example, V d  electrode  860  may need to be biased at 5 V to position movable element  870  to the second position to provide the color blue. However, V d  electrode  860  may in fact be biased at 4.98 V, slightly off from the expected 5 V. As a result, movable element  870  may be positioned at an incorrect position providing a slightly different color than the expected color. When movable element  870  is positioned to the third position, the voltages applied to the electrodes are based on movable element  870  being at the expected position, and therefore, movable element  870  may be positioned to another incorrect position. As movable element  870  is repeatedly positioned, the positioning errors may accumulate such that the actual position of movable element  870  has drifted away from its expected position. 
       FIGS. 6A, 6B, and 6C  illustrate an example of accumulating positioning errors. In  FIGS. 6A, 6B, and 6C , the left side portrays the expected position of movable element  870  and the right side portrays the actual position of movable element  870 , for example, due to V d  electrode  860  being biased at a slightly off voltage. 
     In  FIG. 6A , movable element  870  may be at an initial position that is the same in the expected and actual scenarios. Accordingly, ΔD  905 , representing the difference in position between movable element  870  in the expected and actual scenarios, is zero. Next, in  FIG. 6B , movable element  870  may need to be positioned such that display unit  750  provides a new color, and therefore, new voltages may be applied to one or more of the three electrodes. However, ΔD  905  in  FIG. 6B  shows a non-zero difference between the positions of movable element  870  of the two scenarios as indicated by the dotted lines. That is, the actual position of movable element  870  deviates from the expected position by ΔD  905  due to the aforementioned conditions that allow for an electrode (e.g., V d  electrode  860 ) to be biased at a slightly incorrect voltage. Next, in  FIG. 6C , movable element  870  may need to be positioned again to provide another color. However, since movable element  870  is expected to be at the expected position of  FIG. 6B , the electrodes may be biased with a voltage to position movable element  870  from the expected position in  FIG. 6B  to the expected position in  FIG. 6C . Since the actual position of movable element  870  is different than the expected position in  FIG. 6B , the voltage applied to the electrode may not be proper (i.e., moving from the actual position in  FIG. 6B  to the expected position in  FIG. 6C  may need a different voltage). Accordingly, the actual position of movable element  870  in  FIG. 6C  drifts farther away from the expected position, indicated by the larger ΔD  905 . 
     A reset scheme to position movable element  870  to an intermediate reset position between positions may be used to reduce the accumulation of positioning errors.  FIGS. 7A-E  illustrate an example positioning a movable element with an intermediate reset position. Some implementations of this are described in more detail in U.S. patent application Publication Ser. No. 14/021,866, titled DISPLAY ELEMENT RESET USING POLARITY REVERSAL, by Chan et al., filed on Sep. 9, 2013, and is hereby incorporated by reference in its entirety and for all purposes. 
     In  FIG. 7A , movable element  870  may be at an initial position. Movable element  870  may need to be positioned to a new, second position such that display unit  750  provides a new, second color. However, rather than positioning movable element  870  directly from the initial position to the second position, movable element  870  may be moved to a reset position in  FIG. 7B  before being positioned to the second position in  FIG. 7C . In  FIG. 7B , movable element  870  is positioned towards and/or rests against dielectric  875  as the reset position. In particular, voltages may be applied to the electrodes such that movable element  870  is moved (e.g., by forces created by the electric fields generated upon the application of voltages applied to the electrodes) towards V bias  electrode  855  and may rest against dielectric  875 . Dielectric  875  may be used as a “stop” for movable element  870 , and therefore, may provide a reset position, or consistent starting point, for movable element  870  to move to a new position. Accordingly, after movable element  870  has been positioned to the reset position in  FIG. 7B , it may be positioned to the second position providing the second color in  FIG. 7C . Next, when movable element  870  needs to move to a third, new position providing a third color, it may be repositioned from the second position in  FIG. 7C  back to the reset position in  FIG. 7D , followed by repositioning it in the third position in  FIG. 7E . 
     The reset scheme portrayed in  FIGS. 7A-E  may reduce the accumulation of positioning errors because movable element  870  is moved to a consistent starting point (e.g., resting against dielectric  875 ) between repositioning. As a result, if positioning errors occur from the transition from the reset position in  FIG. 7B  to the second position in  FIG. 7C , the positioning errors may not accumulate because movable element  870  would be repositioned to the reset position in  FIG. 7D  before being repositioned again to  FIG. 7E . Positioning errors from the transition from the positions of  FIGS. 7B to 7C  may be reduced or eliminated by repositioning to the reset position in  FIG. 7D  before repositioning against to the third position associated with the third color in  FIG. 7E . 
     In some implementations, even if movable element  870  should stay at the same position to provide the same color (e.g., between different frames), it may still be positioned to the reset position and then repositioned back to the same position. The polarity of the electric fields of display unit  750  may be switched to reduce charge accumulation, and therefore, movable element  870  associated with a color or position in a first frame may be moved to the reset position, and then moved back to the same position in a second frame to provide the same color, but the voltages on the electrodes of display unit  750  may be changed. The polarities may also be switched when movable element  870  moves to new positions. 
     However, positioning movable element  870  to the reset position may introduce visual artifacts, decrease color saturation, and require extra circuitry to provide the reset functionality. For example, if display or array  30  is operating at a lower frequency (e.g., a 1 Hz refresh rate), then a “ripping” process involving biasing each row of display modules  710  one-after-another such that each row of display units  750  is positioned to the proper positions may be visible due to the reset positioning. 
       FIGS. 8A, 8B, and 8C  illustrate an example of positioning a movable element without an intermediate reset position. Positioning movable element  870  without a reset position may avoid the visual artifacts associated with the intermediate reset position and provide more saturated colors. In particular, movable element  870  may be positioned directly from a first position associated with a first color to a second position associated with a second color through multiple applications of voltages to, for example, V d  electrode  860 . In some implementations, a first voltage may be applied to begin positioning movable element  870  towards a new, intended position and within a range of the intended position. Next, a second voltage may be applied to position movable element  870  within the range to stabilize, or be moved to the intended position within the range, and therefore, display unit  750  may provide the intended color. The second voltage that is applied may be the target voltage that V d  electrode  860  should be at for the intended position. As a result, movable element  870  may be repositioned without an intermediate reset position. Moreover, movable element  870  may be repositioned without accumulated errors. 
     In more detail, the positions that movable element  870  may be positioned to may be among ranges  1105   a - h  in  FIG. 8A . If the movement range of movable element  870  between V bias  electrode  855  and V com  electrode  865  allows for different colors (or wavelengths) of the visible spectrum of the electromagnetic spectrum to be the color provided by the respective display unit  750 , then each of the middle of the ranges  1105   a - h  may be capable of providing different colors. For example, if movable element  870  is positioned in the middle of range  1105   a , then the color red may be provided. If movable element  870  is positioned in the middle of range  1105   g , then the color blue may be provided. If movable element  870  is positioned in the middle of range  1105   d , then the color green may be provided. Though the examples described herein use the middle of ranges  1105   a - 1105   h , in other scenarios, any positions within the ranges may be used. The middle is selected for the examples for illustrative purposes. 
     Different voltages may be applied to the electrodes of display unit  750  in order to move movable element  870  to different positions, as previously discussed. For example, if movable element  870  of display unit  750  is at the middle of range  1105   a  reflecting the color red, and it is intended to be repositioned to the middle of range  1105   d  to reflect the color green, then 4.5 V may be applied to V d  electrode  860 . However, other voltages may be applied if movable element  870  should be positioned to another color other than green (e.g., positioning from red to blue in the middle of range  1105   g  may need 5 V applied to V d  electrode  860 ). Accordingly, each transition from one position associated with one color to another position associated with another color may be performed by applying a specific voltage to an electrode. For example, V com  electrode  865  may be at 0 V, V bias  electrode may switch between 12 V and −12V depending upon a polarity as discussed later herein, and V d  electrode  860  may be applied the voltage corresponding to the transition between the positions and colors. 
     In  FIG. 8B , movable element  870  may need to be repositioned from position  1110  providing the color red in the middle of range  1105   a  to position  1115  providing the color green in the middle of range  1105   d . Accordingly, array driver  22  (including column driver circuit  26  and row driver circuit  24 ) may drive V d  electrode  860  to 4.5 V because the transition from position  1110  and red to position  1115  and green may be performed by providing 4.5 V to V d  electrode  860 . However, as previously discussed, the voltage at V d  electrode  860  may be slightly off, for example, 4.4 V. As a result, movable element  870  may be moved towards position  1115  from position  1110 , but rather than being positioned at the intended position  1115 , movable element  870  may be at a slightly different position within range  1105   d , as in  FIG. 8B . Next, in  FIG. 8C , array driver  22  may bias V d  electrode  860  with a second voltage to stabilize movable element  870  to the intended position within the range to reflect the color green from position  1120  (i.e., the incorrect position of movable element  870  in  FIG. 8B ). For example, when movable element  870  is within range  1105   d , an application of 2 V may allow for it to converge, or reposition, to the middle at position  1115  in range  1105   d . That is, at any point within range  1105   d , an application of 2 V may stabilize movable element  870  in the middle of range  1105   d  at position  1115 . Generally, getting close to the intended position (e.g., within the range) may allow for movable element  870  to converge upon the application of the voltage. 
     As another example, while 4.5 V may be the usual, or expected, voltage normally applied for the transition from position  1110  corresponding to red to position  1115  corresponding to green, some electrodes associated with other movable elements  870  may need a slightly different voltage, for example 4.4 V due to process variations or errors from calibration. If 4.5 V is applied to V d  electrode  860 , then movable element  870  may also be positioned to position  1120  rather than position  1115 . As a result, a similar process as in  FIGS. 8A-C  may be performed as well. 
     If the first application of a voltage to V d  electrode  860  positions movable element  870  at the correct, intended position  1115  (i.e., no positioning errors occurred), then the second application of a voltage to V d  electrode  860  would maintain the position of movable element  870 . 
     Each of ranges  1105   a - 1105   h  may be associated with a voltage range or a number of voltages. If movable element  870  is within the range, the application of a particular voltage may allow for the movable element  870  to stabilize to a particular position within the range (e.g., the middle of the range). For example, if movable element  870  is within range  1105   a , then an application of 2 V may position it to the middle. An application of 2.2 V may position it to a non-middle position. Likewise, if movable element  870  is within range  1105   f , then 2 V may position it to the middle of range  1105   f . If movable element  870  is within range  1105   b , then 2.4 V may position it to the middle of range  1105   b.    
     Accordingly, if the current position of movable element  870  is known, the next, intended position may be provided by determining the proper application of voltages to position movable element between positions (e.g., a transition between the current position to an intended position), providing the voltage for positioning or driving movable element  870  towards the intended position and within a range of the intended position (e.g., as in  FIG. 8B ), and then stabilizing it to the expected and intended position with a subsequent application of voltage (e.g., as in  FIG. 8C ). As such, a two-part technique with an initial driving portion to move movable element  870  towards an intended position and within a range of the intended position may be performed, followed by a stabilizing portion to position movable element  870  to the final, intended position within the range. Therefore, the two-part technique may position movable element  870  without the use of an intermediate reset position. 
       FIG. 9  is a flow diagram illustrating a method to position a movable element without an intermediate reset position. In method  1200 , at block  1205 , a first voltage may be applied to an electrode of a display unit  750  to position a movable element towards a new position. For example, a voltage associated with positioning movable element  870  from a first position providing a first color towards a second position providing a second color may be provided to V d  electrode  860  of display unit  750 . At block  1210 , a second voltage may be applied to V d  electrode  860  of display unit  750  to stabilize movable element  870  in a range such that it positions to the intended position (i.e., the second position providing the second color) from within the range. The method ends at block  1215 . 
     In some implementations, variations to the two-part technique may be performed. For example, positioning movable element  870  from some positions and colors to some other positions and colors may involve a three-part technique. In particular, some positions and colors may not be able to directly transition to another position and color due to hysteresis. For example, an IMOD display element may use, in one implementation, about a 5 volt potential difference to cause the movable reflective layer, or movable element  870  including a mirror, to change from a 4 volt state (or position) to a 5 volt state (or position). However, the movable reflective layer may stay at the 5 volt state as the potential difference drops back below, in this example, 5 volts, because the movable reflective layer does not relax completely until the potential difference drops below 3 volts in this example. Thus the movable reflective layer, in this example, cannot directly transition from the 5 volt state to the 4 volt state. Rather, it has to first transition to a state below 3 volts, then transition to the 4 volt state.  FIGS. 10A, 10B, and 10C  are charts illustrating an example of positioning a movable element in a hysteresis region. 
     In  FIG. 10A , the chart shows the position of movable element  870  on the y-axis and pulse voltage (e.g., a voltage applied to V d  electrode  860 ) on the x-axis. Additionally, the chart shows the colors associated with the positions. 
     In some implementations, movable element  870  at a position associated with the color white may not be able to directly transition to some colors until movable element  870  is “released” from the hysteresis. Releasing movable element  870  from hysteresis may involve positioning movable  870  out of a hysteresis loop (i.e., to a color outside of the hysteresis loop) that may be preventing movable element  870  from directly moving to particular positions within the hysteresis loop. After movable element  870  is released, the two-part technique may be applied. Therefore, transitioning to some positions and colors may need a three-part technique including releasing movable element  870  from hysteresis, driving movable element  870  towards the intended position, and stabilizing to the intended position. 
     For example, in  FIG. 10B , movable element  870  may be at position  1305  associated with the color white. If movable element  870  needs to be positioned to the positions associated with black or blue (i.e., colors associated with positions in a hysteresis region), it may not be able to directly move to the positions. Rather, movable element  870  may need to be released, for example, by first positioning to position  1310  associated with the color green outside of the hysteresis region. Accordingly, the hysteresis region in  FIG. 10B  may be a hysteresis loop such that if movable element  870  is at position  1305  associated with the color white, it cannot be repositioned to the positions providing black or blue in a single transition. When movable element  870  is at the position providing the color green, it may be out of the hysteresis region, and therefore, may be able to be positioned to any available position, including back into the hysteresis region. For example, in  FIG. 10B , movable element  870  may then be able to reposition to position  1315  associated with blue. 
     In additional detail,  FIGS. 11A-D  illustrate an example of positioning a movable element within a hysteresis region. In  FIG. 11A , movable element  870  may be at position  1305  in range  1105   h  such that display unit  750  provides the color white. Position  1315  within range  1105   f  may provide the color blue. Ranges  1105   e - h  may be in a hysteresis region such that movable element  870  may not be able to directly reposition from the white position  1305  in range  1105   h  to a position within ranges  1105   e - g . Rather, movable element  870  may be repositioned to position  1310  providing the color green to be released from the hysteresis region (i.e., outside of ranges  1105   e - h  in the hysteresis region). As a result, in  FIG. 11B , movable element  870  moves from position  1305  providing the color white to position  1310  providing the color green. Next, movable element  870  may be driven towards the intended color to range  1105   f  and stabilized at position  1315 . For example, in  FIG. 11C , movable element  870  may be positioned from position  1310  to within range  1105   f  at position  1315 . Next, in  FIG. 11D , movable element  870  may be stabilized at position  1320  in range  1105   f  to provide the color blue. 
     However, not all positions and colors may be within the hysteresis region. For example, in  FIG. 10C , movable element  870  may be repositioned from a position associated with white in the hysteresis region to a position associated with red without first repositioning to the releasing position (i.e., position  1310  and the color green). Rather, the two-part technique as previously described may be performed because the color red is outside of the hysteresis region. 
       FIG. 12  is a flow diagram illustrating a method to position a movable element in a hysteresis region. In method  1500 , at block  1505 , a voltage may be provided (e.g., to V d  electrode  860 ) to release movable element  870  from the hysteresis region. In block  1510 , a second voltage may be provided to position the movable element towards an intended position and within a range of the intended position. In block  1515 , a third voltage may be provided to stabilize the movable element to the intended position within the range. The method ends at block  1520 . 
       FIG. 13  is an example of a system block diagram for driving a display element. In  FIG. 13 , system  1600  may include circuitry to determine the voltages to be applied, for example, to V d  electrode  860  such that movable element  870  may be positioned without a reset position. 
     In  FIG. 13 , system  1600  includes frame buffer  28 , a storage device to store voltage lookup tables (LUTs)  1610 , driver controller  29 , and array driver  22 . Frame buffer  28  may include information on current image characteristics such as color, as described later herein. Voltage LUTs  1610  may be a voltage data source that may include data indicating voltages for transitions from one color to another color. Driver controller  29  may receive image data  1615 , which may include information on what color each movable element  870  of each display unit  750  should be at next. Driver controller  29  may determine the current color of a movable element  870  by finding its corresponding data in frame buffer  28  and may determine the next color that the movable element  870  should be providing based on image data  1615 . Accordingly, driver controller  29  may know how each movable element  870  should transition. For example, if a movable element  870  of a display unit  750  is at the position providing color green as indicated in frame buffer  28  and that the same movable element  870  should next provide the color red as indicated in image data  1615 , then a transition from green-to-red may need to occur. Voltage LUTs  1610  may be accessed by driver controller  29  to determine the voltages that array driver  22  may need to apply for the green-to-red transition to V column    820 , which may be used to bias V d  electrode  860  when V row    830  is biased to turn transistor T 1   810  in  FIG. 5  on, and therefore, position movable element  870 . 
     Voltage LUTs  1610  may include LUTs providing information for applying three voltages to V d  electrode  860 .  FIGS. 14A, 14B, and 14C  illustrate an example of Lookup Tables (LUTs) for driving a display element. 
     In  FIGS. 14A, 14B, and 14C , the LUTs may be used to implement the two-part technique including driving and stabilizing as well as implement the three-part technique including releasing, driving, and stabilizing. For example, the LUTs may indicate a series of three voltages to be applied to V d  electrode  860  for each color-to-color transition. 
     For a movable element  870  in the hysteresis region (e.g., at the color white) and transitioning to another position within the hysteresis region, the first voltage in a first LUT may indicate the voltage to be applied to release movable element  870 . The second voltage in a second LUT may indicate the voltage to position movable element  870  to the position associated with the intended color. The third voltage in a third LUT may indicate the voltage to stabilize movable element  870  to the position associated with the intended color. 
     For a movable element  870  initially outside of the hysteresis region or transitioning to a subsequent position outside of the hysteresis region, the first voltage in the first LUT may indicate the voltage to apply to position movable element  870  towards the position associated with the intended color. The second voltage in the second LUT may indicate the voltage to apply to stabilize movable element  870  to the intended position. The third voltage in the third LUT may be the same as the second voltage. Since movable element  870  need not be released from a hysteresis region, only two different applications of voltages are needed, and therefore, the third voltage may be a repeat of the second voltage. In other implementations, the first application of voltage may be applied twice instead. 
     For a movable element  870  staying at the same position and color, each voltage indicated in each of the three LUTs may be the same such that movable element  870  does not move to another position. 
     For example, in  FIGS. 14A, 14B, and 14C , each box represents a voltage to be applied to V d  electrode  860  of display unit  750  such that movable element  870  may be positioned properly. The y-axis represents the current color and the x-axis represents the next, intended color of the transition of movable element  870 . The LUTs in  FIGS. 14A and 14B  indicate voltages to be applied for the indicated color transitions. The LUT in  FIG. 14C  indicates the voltage to be applied based on the intended color (i.e., the color to transition to). 
     In  FIG. 14A , a transition from green-to-red indicates that 2.2 V should be applied to V d  electrode  860 . This may be the voltage to position movable element  870  from a position providing the color green to a position providing the color red. However, as previously discussed, V d  electrode  860  may receive a voltage slightly off from 2.2 V. Next, in  FIG. 14B , a second LUT indicates that 4.8 V should be applied to position movable element  870  such that it stabilizes to the position providing the color red. In  FIG. 14C , a third LUT indicates the same voltage as the second LUT for the intended color. 
     A transition from green-to-green should apply 5 V to V d  electrode  860 , which may be a voltage already applied to it because movable element  870  should not move. Accordingly, each of the LUTs in  FIGS. 14A, 14B, and 14C  indicate 5 V for the green-to-green transitions and the final intended color of green. 
     In  FIG. 14A , a transition from white-to-blue indicates that 6.2 V should be applied to V d  electrode  860 . This may be the voltage to position movable element  870  to the position providing green outside of the hysteresis region so that movable element  870  is released from hysteresis. In  FIG. 14B , a white-to-blue transition in the second LUT indicates that 8 V should be applied. This may be the voltage to position movable element  870  from the position providing green to the position providing blue. Next, in  FIG. 14B , 2 V may be applied. This may be the voltage to stabilize movable element  870  to the position providing blue. 
     The LUTs may be organized in different ways.  FIGS. 15A, 15B, and 15C  illustrate another example of LUTs for driving a display element. In  FIGS. 15A, 15B, and 15C , the boxes with the label “1” may be used for a green-to-red transition (i.e., a transition outside of the hysteresis region), boxes with the label “2” may be used for a white-to-blue transition (i.e., a transition inside the hysteresis region to another position within the hysteresis region), and boxes with the label “3” may be used for green-to-green transitions (i.e., staying at the same color). For example, in  FIG. 15A , a green-to-red transition may first apply a voltage corresponding with the green-to-red transition in  FIG. 15A  to position movable element  870  towards the intended position providing red. Next, in  FIG. 15B , the voltage indicated in the red-to-red transition may indicate the next voltage to apply to stabilize movable element  870  because movable element  870  should be in the range including red. In  FIG. 15C , the voltage indicated by the intended color red is then applied, which may be the same as indicated in  FIG. 15B . 
     The above examples of voltages are provided for illustrative purposes. Other implementations may involve other voltages and/or LUTs. 
     In some implementations, the three voltages may be applied in three different “rips” through each row of display units  750  of the display. For example, in a first rip, each V d  electrode  860  of each display unit  750  in a first row may be applied the first voltage as indicated in the first LUT, followed by each movable element  870  of each display unit  750  in a second row, and so on, until each V d  electrode  860  of each display unit  750  is biased to allow for the corresponding movable element  870  to be released (if in the hysteresis region and transitioning to another position and color in the hysteresis region), driven towards the intended position and color (if transitioning to a position and color outside of the hysteresis region), or be maintained (if the color should not change). Next, each row, row-by-row, may be applied the second voltage as indicated in the second LUT. After each row in the display is provided the second voltage, each row may then be provided the voltages as indicated in the third LUT. 
     Additionally, the polarities of the electric fields of display unit  750  may also be switched between rips. For example, if V com  electrode  865  is 0 V and the voltages indicated in the LUTs are provided to the V d  electrode  860 , the voltage applied to V bias  electrode  855  may alternate between a positive and negative voltage (e.g., 12 V and −12 V) to reverse the directions of the electric fields, and therefore, reduce charge accumulation across display unit  750 . For example, the voltage applied to V bias  electrode  855  may switch before or after an application of voltage to V d  electrode  860 . 
     In some implementations, the third rip may not be performed. In particular, the second rip may stabilize movable element  870  for colors outside of hysteresis. For colors within hysteresis and transitioning to another color within hysteresis, enough stability may be provided by first releasing to the position and color outside of the hysteresis region. However, in other implementations, applications of the third rip may be repeated to provide further stability. 
     Though only three LUTs are shown in the preceding examples, more LUTs may be used. For example, additional LUTs may be used to further take into account polarities. For example, a positive frame with display units  750  having a positive polarity may transition to a negative frame with display units  750  having a negative polarity, and vice versa. The transitions to the same positions and colors, but with different polarities, may have different LUTs. 
     Additionally, the LUTs may indicate any number of colors that may be transitioned from or towards. For example, the LUTs herein include eight colors, but any number of colors may be used by the LUTs. 
       FIGS. 16A and 16B  are system block diagrams illustrating a display device  40  that includes a plurality of IMOD display elements. The display device  40  can be, for example, a smart phone, a cellular or mobile telephone. However, the same components of the display device  40  or slight variations thereof are also illustrative of various types of display devices such as televisions, computers, tablets, e-readers, hand-held devices and portable media devices. 
     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  FIG. 16A . The display device  40  includes a housing  41  and can include additional components at least partially enclosed therein. For example, the display device  40  includes a network interface  27  that includes an antenna  43  which can be coupled to a transceiver  47 . The network interface  27  may be a source for image data that could be displayed on the display device  40 . Accordingly, the network interface  27  is one example of an image source module, but the processor  21  and the input device  48  also may serve as an image source module. The transceiver  47  is connected to a processor  21 , which is connected to conditioning hardware  52 . The conditioning hardware  52  may be configured to condition a signal (such as filter or otherwise manipulate a signal). The conditioning hardware  52  can be connected to a speaker  45  and a microphone  46 . The processor  21  also can be connected to an input device  48  and a driver controller  29 . The driver controller  29  can be coupled to a frame buffer  28 , and to an array driver  22 , which in turn can be coupled to a display array  30 . One or more elements in the display device  40 , including elements not specifically depicted in  FIG. 16A , can be configured to function as a memory device and be configured to communicate with the processor  21 . In some implementations, a power supply  50  can provide power to substantially all components in the particular display device  40  design. 
     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&#39;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. 
     If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. The steps of a method or algorithm disclosed herein may be implemented in a processor-executable software module which may reside on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program from one place to another. A storage media may be any available media that may be accessed by a computer. By way of example, and not limitation, such computer-readable media may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that may be used to store desired program code in the form of instructions or data structures and that may be accessed by a computer. Also, any connection can be properly termed a computer-readable medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk, and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above also may be included within the scope of computer-readable media. Additionally, the operations of a method or algorithm may reside as one or any combination or set of codes and instructions on a machine readable medium and computer-readable medium, which may be incorporated into a computer program product. 
     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.