HK1087191A - System and method of illuminating interferometric modulators using backlighting - Google Patents

Abstract

An interferometric modulator array device with backlighting is disclosed. The interferometric modulator array device comprises a plurality of interferometric modulator elements, wherein each of the interferometric modulator elements comprises an optical cavity. The interferometric modulator array includes an optical aperture region, and at least one reflecting element is positioned so as to receive light passing through the optical aperture region and reflect at least a portion of the received light to the cavities of the interferometric modulator elements. In some embodiments, the interferometric modulator elements may be separated from each other such that an optical aperture region is formed between adjacent interferometric modulator elements.

Description

System and method for illuminating interferometric modulators using backlighting

Technical Field

The present invention relates generally to a system and method of illuminating a display, and more particularly to a system and method of illuminating a display using backlighting and one or more reflective elements.

Background

Microelectromechanical Systems (MEMS) include micromechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, 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 MEMS device is known as an interferometric modulator. An interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. One of the plates may comprise a stationary layer deposited on a substrate and the other plate may comprise a metal diaphragm separated from the stationary layer by an air gap. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their performance can be exploited in improving existing products and creating new products that have not yet been developed.

For some applications, the interferometric modulator devices may be arranged in an array configuration to provide a display assembly with better operating and performance characteristics. For example, these displays may have rich color characteristics and low power consumption.

The interferometric modulator devices in such displays operate by reflecting light and generating optical interference. An array of interferometric modulators may operate by modulating the ambient light reflected from the array. However, when ambient light is not available or is insufficient, auxiliary lighting, such as that provided by backlighting, is required. Accordingly, it is desirable to provide systems and methods for illuminating an array of interferometric modulators.

Disclosure of Invention

The system, method and apparatus of the present invention have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the invention, its more prominent features will now be discussed briefly. After reviewing this discussion, and particularly after reading the section entitled "detailed description of certain embodiments" one will understand how the features of this invention provide advantages over other display devices.

An embodiment of a spatial light modulator includes a light modulating array comprising a plurality of light modulating elements, each light modulating element having a cavity defined by first and second optical surfaces, wherein the second optical surface is movable relative to the first optical surface. The light modulating array includes at least one optical aperture region. The light modulating array device further includes at least one reflective element formed between a substrate and a plurality of light modulating elements and configured to receive light passing through the optical aperture region and reflect at least a portion of the received light to the cavity. In some embodiments, backlighting is thereby facilitated.

The at least one reflective element may comprise at least one of aluminum, silver, titanium, gold, and copper. In addition, the at least one reflective element may have an inclined surface.

The reflective element may have a substantially convex geometry or a substantially concave geometry. In addition, the at least one reflective element may include interconnected portions to form a continuous unitary structure extending proximate to the plurality of light modulation elements.

The spatial light modulator may further comprise a mask aligned with the at least one reflective element to at least partially block a line of sight of the at least one reflective element. The mask may comprise at least a portion of an aligner, and the portion of the aligner may comprise one or more layers of partially reflective material and one or more spacer layers.

In certain embodiments, the at least one reflective element comprises at least one shaping device and a reflective material on the shaping device.

A substrate of a light modulating array can include at least one cavity, wherein the at least one reflective element is formed within the cavity of the substrate. The at least one reflective element may comprise a substantially granular reflective material suspended in a substantially transparent material.

In some embodiments, the plurality of light modulating elements comprises a metal layer, wherein the metal layer comprises a plurality of transmissive apertures. At least some of the light modulation elements may be separated from each other to form an optical aperture region therebetween.

An embodiment of a method of fabricating a spatial light modulator includes forming at least one reflective element on a substrate and forming a plurality of light modulation elements over the at least one reflective element on the substrate to form a light modulation array. Each light modulation element includes first and second optical surfaces that define a cavity, wherein the second optical surface is movable relative to the first optical surface. The light modulating array has at least one transmissive aperture region. The at least one reflective element is configured to receive light passing through the at least one aperture region and reflect at least a portion of the received light into the cavity.

Forming the at least one reflective element may include depositing at least one of aluminum, silver, titanium, gold, and copper, and forming the at least one reflective element may include depositing one or more materials to form a substantially sloped surface, a substantially convex geometry, or a substantially concave geometry. In some embodiments, forming the at least one reflective element includes forming a shaped base structure on the substrate and depositing a reflective material on the shaped base structure.

The method may further include forming a cavity in a substrate and forming the at least one reflective element substantially within the cavity of the substrate. Forming the at least one reflective element may comprise depositing a layer of reflective material on a substrate and surface treating the layer to increase the reflectivity and/or scattering of the reflective material.

In some embodiments, the method further comprises forming a masking device on the substrate in alignment with the at least one reflective element to mask the visual presence of the at least one reflective element. The masking device may comprise a mask formed of at least one of an absorptive material, a reflective material and a transmissive material. The masking device may comprise a masking layer formed from at least one of a carbon black material, a dye, chromium and molybdenum. In certain embodiments, the masking device comprises a metal film to form an etalon comprising the metal film and the at least one reflective element. The calibrator may be configured to appear to an observer as a predetermined color.

In an embodiment of the method, forming the at least one reflective element comprises depositing a composite material on the substrate surface, wherein the composite material comprises reflective particles suspended in a substantially transparent material. The composite material may be deposited at discrete locations on a surface of a substrate to form a plurality of reflective elements; or the composite material may be deposited as one continuous layer on the substrate surface, thereby forming a single reflective element structure.

In certain embodiments, the light modulating element comprises an interferometric modulator element and the light modulating array comprises an array of interferometric modulators. However, in other embodiments, other types of light modulators may be used, including other types of MEMS structures.

An embodiment of a method of backlighting an interferometric modulator array includes disposing a light source proximate a first side of the interferometric modulator array and reflecting light from the light source to a second, opposing side of the interferometric modulator array. In certain embodiments, light is reflected using one or more reflective elements disposed between a substrate and a plurality of interferometric modulator elements formed on the substrate. Additionally, the method may further comprise masking the one or more reflective elements so that they are not visible, and the masking may comprise forming at least a portion of an aligner between the one or more reflective elements and an observer.

In some embodiments of the method, the light is reflected using a plurality of discrete reflective elements, and the light is reflected using one or more reflective elements having an angled surface. One or more convex reflective elements or one or more concave reflective elements may be utilized to reflect light. The light may be reflected using one or more reflective elements comprising at least one of aluminum, silver, titanium, gold, or copper.

Drawings

FIG. 1 is an isometric view depicting a portion of one embodiment of an interferometric modulator display in which a movable reflective layer of a first interferometric modulator is in a released position and a movable reflective layer of a second interferometric modulator is in an actuated position.

FIG. 2 is a system block diagram illustrating one embodiment of an electronic device including a 3 × 3 interferometric modulator display.

FIG. 3 is a diagram of movable mirror position versus applied voltage for one exemplary embodiment of an interferometric modulator of FIG. 1.

FIG. 4 is a schematic diagram of a set of row and column voltages that may be used to drive an interferometric modulator display.

Fig. 5A and 5B show an exemplary timing diagram for row and column signals that may be used to write a frame of display data to the 3 x 3 interferometric modulator display of fig. 2.

Fig. 6A is a cross-sectional view of the device of fig. 1.

FIG. 6B is a cross-sectional view of an alternative embodiment of an interferometric modulator.

FIG. 6C is a cross-sectional view of another alternative embodiment of an interferometric modulator.

FIG. 7 is a plan view of an array of interferometric modulators, showing electrodes used to drive the array of interferometric modulators.

FIG. 8A is a plan view of one embodiment of an interferometric modulator array comprising a plurality of interferometric modulator elements separated by aperture regions.

FIG. 8B is a cross-sectional view of the interferometric modulator array of FIG. 8A, illustrating illumination by the backlighting element.

FIG. 9A is a cross-sectional view of one embodiment of a reflective element comprising more than one material.

FIG. 9B is a cross-sectional view of one embodiment of a convex reflective element formed in a cavity.

FIG. 9C is a cross-sectional view of one embodiment of a concave reflective element formed in a cavity.

FIG. 10 is a cross-sectional view of a reflective element and a mask configured to mask the reflective element from an observer.

FIG. 11 is a plan view of an array of interferometric modulators showing an upper electrode layer patterned to form a plurality of optical aperture regions through which light is transmitted.

FIGS. 12A and 12B are system block diagrams illustrating one embodiment of a visual display device comprising a plurality of interferometric modulators.

Detailed Description

As discussed more fully below, in certain preferred embodiments, one or more reflective elements may be integrated into a display to direct light from a backlight to nearby interferometric modulator elements. An array of interferometric modulators may include one or more aperture regions through which illumination from a backlight illumination source propagates. For example, the aperture region may be located between adjacent interferometric modulator elements. The one or more reflective elements are formed between a substrate and the array of interferometric modulators. The reflective element may be positioned to receive light passing through the aperture region and reflect the received light into an optical cavity of the interferometric modulator. The reflective element may have a curved surface or an inclined surface that can direct light as desired. The reflective element may comprise a reflective material, such as aluminum or silver. In some embodiments, the reflective element may comprise a base material, such as a photoresist and a reflective covering material (e.g., aluminum or silver). The reflective elements may be formed on or in the substrate and covered by planarization. The efficiency of the backlighting can be increased by using these reflective elements. These reflective elements may also prevent light from leaking through the front of the display.

The following detailed description is directed to certain specific embodiments of the invention. However, the invention can be embodied in a multitude of different ways. In the description, reference is made to the drawings wherein like parts are designated with like numerals throughout. As will be apparent from the following description, the invention may be implemented in any device that is configured to display an image, whether in motion (e.g., video) or stationary (e.g., still image), and whether textual or pictorial. More specifically, the invention may be implemented in or associated with a variety of electronic devices such as, but not limited to, the following: mobile telephones, wireless devices, Personal Data Assistants (PDAs), handheld or portable computers, GPS receivers/navigators, cameras, MP3 players, camcorders, game consoles, wrist watches, clocks, calculators, television monitors, flat panel displays, computer monitors, auto displays (e.g., rangefinder display, etc.), cockpit controls and/or displays, display of camera views (e.g., display of a rear view camera in a vehicle), electronic photographs, electronic billboards or signs, projectors, architectural structures, packaging, and aesthetic structures (e.g., display of images on a piece of jewelry). MEMS devices of similar construction to the MESE devices described herein can also be used in non-display applications such as in electronic switching devices.

One interferometric modulator display embodiment comprising an interferometric MEMS display element is shown in FIG. 1. In these devices, the pixels are in either a bright or dark state. In the bright ("on" or "open") state, the display element reflects a large portion of incident visible light to the user. When in the dark ("off" or "closed") state, the display element reflects little incident visible light to the user. Depending on the embodiment, the light reflectance properties of the "on" and "off" states may be reversed. MEMS pixels can be configured to reflect predominantly at selected colors, allowing for a color display in addition to black and white.

FIG. 1 is an isometric view depicting two adjacent pixels in a series of pixels of a visual display, wherein each pixel comprises a MEMS interferometric modulator. In certain embodiments, an interferometric modulator display comprises a row/column array of these interferometric modulators. Each interferometric modulator includes a pair of reflective layers positioned at a variable and controllable distance from each other to form a resonant optical cavity with at least one variable dimension. In one embodiment, one of the reflective layers is movable between two positions. In the first position, referred to herein as the released state, the movable layer is positioned relatively far from a fixed partially reflective layer. In the second position, the movable layer is positioned closer to the partially reflective layer. Incident light that reflects from the two layers interferes constructively or destructively depending on the position of the movable reflective layer, producing either an overall reflective or non-reflective state for each pixel.

The portion of the pixel array shown in FIG. 1 includes two adjacent interferometric modulators 12a and 12 b. In the interferometric modulator 12a on the left, a movable highly reflective layer 14a is illustrated in a released position at a predetermined distance from a fixed partially reflective layer 16 a. In the interferometric modulator 12b on the right, a movable highly reflective layer 14b is illustrated in an actuated position adjacent to a fixed partially reflective layer 16 b.

The fixed layers 16a, 16b are electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more layers each of chromium and indium tin oxide on a transparent substrate 20. The layers are patterned into parallel strips and may form row electrodes in a display device, as will be described further below. The movable layers 14a, 14b may be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes 16a, 16 b) deposited on top of posts 18 and an intervening sacrificial material deposited between the posts 18. After the sacrificial material has been etched away, the deformable metal layers are separated from the fixed metal layers by a defined air gap 19. The deformable layers may be formed from a highly conductive and reflective material, such as aluminum, and the strips may form column electrodes in a display device.

When no voltage is applied, the cavity 19 remains between the layers 14a, 16a and the deformable layer is in a mechanically relaxed state as shown by the pixel 12a in FIG. 1. However, after application of a potential difference to a selected row and column, the capacitor formed at the intersection of the row and column electrodes at the corresponding pixel becomes charged, and electrostatic forces pull the electrodes together. If the voltage is high enough, the movable layer deforms and is forced against the fixed layer (a dielectric material (not shown in this figure) may be deposited over the fixed layer to prevent shorting and control the separation distance), as shown in the right pixel 12b in FIG. 1. The behavior is the same regardless of the polarity of the applied potential difference. It can thus be seen that row/column actuation that can control the reflective vs. non-reflective pixel states is analogous in many ways to that used in conventional LCD and other display technologies.

Fig. 2-5 illustrate one exemplary process and system for using an array of interferometric modulators in a display application. FIG. 2 is a system block diagram illustrating one embodiment of an electronic device that may embody aspects of the invention. In the exemplary embodiment, the electronic device includes a processor 21, which may be any general purpose single-or multi-chip microprocessor such as an ARM, Pentium *, Pentium II *, Pentium III *, Pentium IV *, Pentium * Pro, 8051, MIPS *, Power PC *, ALPHA *, or any special purpose microprocessor such as a digital signal processor, microcontroller, or programmable gate array. As is conventional in the art, the processor 21 may be configured to execute one or more software modules. In addition to executing an operating system, the processor 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.

In one embodiment, the processor 21 is further configured to communicate with an array controller 22. In one embodiment, the array controller 22 includes a row driver circuit 24 and a column driver circuit 26 that provide signals to a pixel array 30. The cross-sectional view of the array shown in FIG. 1 is shown by line 1-1 in FIG. 2. For MEMS interferometric modulators, the row/column actuation protocol may take advantage of the hysteresis properties of these devices shown in FIG. 3. It may require, for example, a 10 volt potential difference to cause a movable layer to deform from the released state to the actuated state. However, when the voltage is reduced from this value, the movable layer will retain its state as the voltage drops back below 10 volts. In the exemplary embodiment of FIG. 3, the movable layer does not release completely until the voltage drops below 2 volts. Thus, in the example shown in FIG. 3, there is a range of voltage, approximately 3-7 volts, within which there exists a window of applied voltage within which the device is stable in either the released or actuated state. This is referred to herein as the "hysteresis window" or "stability window". For a display array having the hysteresis characteristics of FIG. 3, the row/column actuation protocol can be designed to apply a voltage difference of about 10 volts to the pixels to be actuated in the selected pass and a voltage difference of approximately 0 volts to the pixels to be released during row strobing. After the strobe, the pixels are exposed to a steady state voltage difference of about 5 volts such that they remain in whatever state the row strobe put them in. After being written, each pixel sees a potential difference within the "stability window" of 3-7 volts in this example. This feature makes the pixel design shown in fig. 1 stable under the same applied voltage conditions in either an actuated or released pre-existing state. Since each pixel of the interferometric modulator, whether in the actuated or released state, is essentially a capacitor formed by the fixed and moving reflective layers, this stable state can be held at a voltage within the hysteresis window with almost no power dissipation. Essentially no current flows into the pixel if the applied potential is constant.

In typical applications, a display frame may be created by asserting the set of column electrodes in accordance with the desired set of actuated pixels in the first row. A row pulse is then applied to the row 1 electrode, actuating the pixels corresponding to the asserted column lines. The asserted set of column electrodes is then changed to correspond to the desired set of actuated pixels in the second row. A pulse is then applied to the row 2 electrode, actuating the appropriate pixels in row 2 in accordance with the asserted column electrodes. The row 1 pixels are unaffected by the row 2 pulse, and thus remain in the state they were set to during the row 1 pulse. The above steps may be repeated for the entire series of rows in a sequential manner to form the frame. Typically, the frames are refreshed and/or updated by repeating the process at some desired number of frames per second. A wide variety of protocols for driving row and column electrodes of pixel arrays to produce display frames are also well known and may be used in conjunction with the present invention.

Fig. 4 and 5 show one possible actuation protocol for forming a display frame on the 3 x 3 array of fig. 2. FIG. 4 shows a possible set of row and column voltage levels that may be used for pixels having the hysteresis curves of FIG. 3. In the embodiment of FIG. 4, actuating a pixel involves setting the appropriate column to-Vbias, and the appropriate row to + Δ V, which may correspond to-5 volts and +5 volts, respectively. Releasing a pixel is accomplished by setting the corresponding column to + Vbias, and the corresponding row to the same + deltav, thereby creating a 0 volt potential difference across the pixel. In those rows where the row voltage is held at 0 volts, the pixels are stable in the state they were originally in, regardless of whether the column is at + Vbias, or-Vbias.

FIG. 5B is a timing diagram showing a series of row and column signals applied to the 3 × 3 array of FIG. 2, which will result in the display arrangement of FIG. 5A, where actuated pixels are non-reflective. Prior to writing the frame shown in FIG. 5A, the pixels can be in any state, in this example, all the rows are at 0 volts, and all the columns are at +5 volts. Under these applied voltages, all pixels are stable in their existing actuated or released states.

In the frame shown in FIG. 5A, pixels (1, 1), (1, 2), (2, 2), (3, 2) and (3, 3) are activated. To accomplish this, column 1 and column 2 are set to-5 volts, and column 3 is set to +5 volts during the line time for row 1. This does not change the state of any pixels, since all pixels remain within the 3-7 volt stability window. Thereafter, row 1 is strobed with a pulse that rises from 0 volts to 5 volts and then falls back to 0 volts. Thereby actuating the pixels (1, 1) and (1, 2) and releasing the pixels (1, 3). No other pixels in the array are affected. To set row 2 as desired, column 2 is set to-5 volts, and columns 1 and 3 are set to +5 volts. Thereafter, applying the same strobe to row 2 will actuate pixel (2, 2) and release pixels (2, 1) and (2, 3). Again, no other pixels in the array are affected. Similarly, row 3 is set by setting columns 2 and 3 to-5 volts, and column 1 to +5 volts. The row 3 strobe sets the row 3 pixels to the state shown in FIG. 5A. After writing the frame, the row potentials are 0, while the column potentials can remain at either +5 or-5 volts, and the display will thereafter be stable in the arrangement shown in FIG. 5A. It will be appreciated that the same procedure can be used for arrays consisting of tens or hundreds of rows and columns. It will also be appreciated that the timing, sequence, and levels of voltages used to perform row and column actuation can be varied widely within the general principles outlined above, and the above example is exemplary only, and any actuation voltage method can be used with the present invention.

The detailed structure of interferometric modulators that operate in accordance with the principles set forth above may vary widely. For example, FIGS. 6A-6C show three different embodiments of the moving mirror structure. FIG. 6A is a cross-sectional view of the embodiment of FIG. 1, wherein a strip of metal material 14 is deposited on orthogonally extending supports 18. In FIG. 6B, the moveable reflective material 14 is attached to supports at the corners only, on tethers 32. In FIG. 6C, the moveable reflective material 14 is suspended from a deformable layer 34. This embodiment has advantages because the structural design and materials used for the reflective material 14 can be optimized with respect to the optical properties, and the structural design and materials used for the deformable layer 34 can be optimized with respect to desired mechanical properties. The production of various types of interference devices is described in a number of published documents, including, for example, U.S. published application No. 2004/0051929. The above-described structures may be fabricated using a variety of well-known techniques, including a series of material deposition, patterning, and etching steps.

Interferometric modulators, such as those included in an array of interferometric modulators, for example, that constitute a spatial light modulator, may also be referred to herein as "interferometric modulator elements".

FIG. 7 is a top view of an example interferometric modulator array 500 on a substantially transparent substrate 554, such as glass. In one process as described above, multiple material layers are patterned to form lower electrode columns 550A-C and upper electrode rows 552A-C as shown in FIG. 7. Although not visible in FIG. 7, an optical cavity or etalon defined by upper and lower mirrors (not shown) is formed at the intersection of row electrodes 552A-C and column electrodes 550A-C. Although in the embodiment shown, 9 interferometric modulator elements 525 are shown formed by three columns of electrodes 550A-C and three rows of electrodes 552A-C, a larger or smaller array 500 may include more or fewer interferometric modulators. Alternative configurations are also possible. For example, the interferometric modulator elements 525 need not be the same size and shape, nor need they be arranged in vertical columns and horizontal rows. Alternatively, the space occupied by the interferometric modulator element 525 at a given intersection of a column electrode and a row electrode may instead comprise a plurality of interferometric modulator elements having smaller dimensions than those shown.

In addition, the array 500 can also be fabricated with different upper mechanical electrodes, e.g., one for each interferometric modulator 525, rather than only a single electrode 552 traversing a row of interferometric modulators. The separate upper mechanical electrode can be electrically contacted by, for example, a separate layer. In addition, certain portions of the electrodes (e.g., upper mechanical electrode 552) connecting the individual modulators 525 in a row may have a reduced width. These reduced width electrode portions may provide narrower connecting lines between the interferometric modulators 525 than shown in FIG. 7. As discussed more fully below, in certain embodiments, narrow electrode portions connecting the various modulators may be located, for example, on the corners of the interferometric modulator 525.

As shown in FIG. 7, each column 550A-C is electrically connected to a contact pad 556A-C. Each row 552A-C is also electrically connected to a contact pad 556D-F. Timing and data signals may be connected to the contact pads 556 to address the interferometric modulator array. However, as noted above, the embodiment shown is an exemplary embodiment, as other configurations and designs can be used, such as an interferometric modulator array with no electrical contacts.

In certain embodiments, backlighting is used to illuminate a display comprising at least one array 500 of interferometric modulators, such as shown in FIG. 8A. In these configurations, the interferometric modulator array 500 may be designed to receive illumination from the back side or an invisible side of the interferometric modulator array.

In the array 500 shown in FIG. 8A, the spaces 574 between the interferometric modulator elements 525 form the optical aperture region, as seen on a non-visible side of the array. The portion of the interferometric modulator 525 shown in FIG. 8A corresponds to the mechanical layer 570 that supports the upper mirror (not shown) as described above with respect to FIGS. 1-6C. The array 500 is fabricated with different or separate portions of the upper mechanical electrode, for example, one portion for each interferometric modulator element 525 rather than only a single electrode strip through a row of interferometric modulators as shown in FIG. 7. These portions 570 of the mechanical layer are separated to form an aperture region or space 574 therebetween that is optically transmissive. As described above, each discrete upper mechanical electrode 570 may be electrically contacted by, for example, a separate layer.

In the exemplary embodiment shown in FIG. 8A, discrete portions of the upper mechanical electrode 570 form a grid-like shaped spacing between the interferometric modulators 525. The optically transmissive aperture regions 574 in the upper electrode layer 570 can be substantially free of material, and/or these optically transmissive aperture regions can comprise a material that is substantially optically transmissive.

The spaces or aperture regions in the interferometric modulator array 500 are not limited to those formed between pixels of a display, but may also include, for example, spaces between a plurality of interferometric modulator elements corresponding to sub-pixel elements within a pixel. These sub-pixels may be used to provide a larger range of colors or gray scales in a multi-color or gray scale display, respectively. In certain embodiments, the interferometric modulator array comprises one or more optically transmissive aperture regions in the mechanical layer and the mirror of one or more interferometric modulator elements. As described above, the one or more optically transmissive aperture regions may be substantially free of material, and/or the optically transmissive aperture regions may comprise material that is substantially optically transmissive.

In an embodiment, the array of interferometric modulators may comprise one or more substantially centered optically transmissive aperture regions. Certain embodiments of an interferometric modulator device may comprise optically transmissive aperture regions in a combination of the above positions and configurations, e.g., both between adjacent interferometric modulator elements and in the mechanical layers and mirrors of one or more interferometric modulator elements.

In one embodiment, the optically transmissive aperture region 574 has a substantially constant width w. The width w may be determined by the minimum outline dimensions or other design rules of the manufacturing process. In general, the space 574 between adjacent portions of the mechanical layer 570 of different interferometric modulators 525 is as small as possible to avoid wasting any pixel area. However, the width w may vary depending on, for example, the size and design of the display device or other factors, and is not limited to the embodiments described and illustrated herein. For example, the optical aperture region 574 between different portions of the mechanical layer 570 can be made larger than the minimum size to increase the amount of light passing through the optical aperture region 574 and impinging on the interferometric modulator element 525. In various embodiments, the width of aperture region 574 is between about 2 microns and 15 microns, although the width can be outside of this range. Additionally, the length of the aperture region 574 can be between about 10 microns and 100 microns, although lengths outside this range can also be used. The width and length of the aperture region 574 need not be constant, but can be varied across the array, for example, to control the light illumination at different locations in the array 500. Accordingly, the size and shape of the interferometric modulator element 525 and the corresponding portions of the mechanical layer 570 need not be uniform, but may vary. For example, in some embodiments, the size of the interferometric modulator elements 525 of different sub-pixels within a pixel are pulsed to provide more color or gray scale.

FIG. 8B is a cross-sectional view of the interferometric modulator array 500 of FIG. 8A taken along line 8B-8B. FIG. 8B shows an embodiment in which a backlight 575 is disposed proximate a first invisible side 577 of the interferometric modulator array 500. The backlight 575 is configured to distribute light over different portions of the mechanical layer 570 and through the optically transmissive aperture area 574. In some embodiments, the backlight 575 is elongated in one or more dimensions. However, the backlight 575 shown in FIG. 8B is merely exemplary, as other types of backlights can be used.

In some embodiments, the backlight 575 may include, for example, discrete light sources, such as light emitting diodes. The backlight 575 may also include a combination of one or more emitters and optics, such as a waveguide configured to pass or propagate light from the emitters to the interferometric modulator array 500. An optically transmissive layer extending over the entire array 500 may, for example, serve as a waveguide for coupling light to the interferometric modulator 525. Emitters may be arranged at the edge of such a waveguide to inject light into the waveguide.

As shown in FIG. 8B, one or more light reflecting elements 572 are included in the display to direct light from the backlight 575 into the optical cavities 584 in each interferometric modulator 525. The reflective element 572 is configured to reflect light from the backlight 575 that passes through optically transmissive aperture regions 574 between the interferometric modulator elements 525. The reflective element has a reflective surface 573 that directs light into the optical cavity 574 of the interferometric modulator 525. The light reflecting element 572 may also be referred to as a "scattering element," wherein the reflecting element 572 is further configured to scatter or deflect light into the optical cavities 574 to fill the cavities with light.

The reflective element 572 can comprise, for example, a grid-like reflective element aligned with optically transmissive aperture regions 574 between rows and columns of interferometric optical elements 525. Unitary structure 572 can, for example, include cylindrical or elongated reflective portions aligned parallel to the rows and columns of modulators 525. FIG. 8B shows a cross-section of a cylindrical or elongated reflective portion that forms part of this grid-like reflective element 572. FIG. 8B shows that the reflective surface 573 of the reflective element 572 is configured to direct light into the optical cavity of the interferometric modulator 525.

Alternatively, a plurality of reflective elements 572 comprising, for example, a plurality of discrete structures (e.g., dots or separate elongated portions) may be used. These discrete structures may include, for example, bumps, mounds, or ridges having a reflective surface. The reflective elements 572 can be positioned in a regular (uniform) or irregular (random) arrangement. Reflective element 572 may also have more complex shapes or geometries. For example, a grid-like pattern may be divided into other shapes (e.g., "+" or "L" -shaped elements) other than columns and rows. Other shapes that may or may not together form a grid-like pattern are also possible. However, as noted above, a single reflective element 572 may be used in some embodiments.

As shown in FIG. 8B, a reflective element 572 is disposed on the substrate 554 between the substrate and the interferometric modulator element 525. The reflective element 572 may have portions disposed proximate to optically transmissive aperture regions 574 located between different portions of the mechanical layer 570. Accordingly, a corresponding portion of the reflective surface 573 is proximate to the optically transmissive aperture region 574. In an embodiment, the reflective element 572 or portions thereof are aligned with the aperture region 574 and the reflective element 572 or portions thereof are visible through the aperture region when viewed from the non-visible side 577 shown in fig. 8A.

The reflective element 572 is configured to receive light from a backlight 575 disposed proximate a non-visible or first side of the interferometric modulator array 500, in which the mechanical layer 570 (identified using arrow 577) is disposed, and through an optically transmissive aperture region 574, and reflect the received light to a second side 579 of the interferometric modulator array that is visible to a viewer. This second side 579 of the interferometric modulator array that is visible to an observer is opposite the first side of the interferometric modulator array where the backlight 575 is disposed. FIG. 8B also shows an optical cavity 584 formed in each interferometric modulator element 525 between an upper mirror 571a, which extends from the mechanical layer 570, and a lower mirror 571B, which comprises, for example, a metal layer 578 formed over the substrate 554. As described above, the reflective surface 573 on the reflective element 572 is shaped to reflect and/or scatter light into the optical cavity 584.

In the embodiment shown in FIG. 8B, the reflective element 572 has a substantially convex cross-section relative to the substrate 554. Accordingly, the cross-section of the reflective element is tilted on the opposite side, with portions of the reflective surface 573 being deflected towards the aperture region 574 and facing the adjacent optical cavity 584. The reflective surface 573 is shown as being curved. However, the geometry of the reflective element 572 is not limited to that shown and described herein, as other geometries are contemplated. For example, the reflective elements may have flat or planar portions that may or may not be tilted/inclined relative to the substrate 554. For example, the cross-section may be triangular in shape. Other shapes are also possible. The profile may, for example, be substantially concave. As noted above, portions of the reflective element may be stretchable. Alternatively, the various portions need not be elongate, for example in the case of bumps, bumps or dots, which may be substantially circumferentially symmetrical in some embodiments. Alternatively, the reflective element may have a non-uniform geometric profile. Additionally, although the reflective surface 573 is shown as being substantially smooth, the reflective surface can also be uneven. The reflective surface may be stepped or serrated. As described above, the reflection from the reflective surface 573 may be diffuse or specular.

The reflective element may also be surface treated to improve reflectivity and scattering properties. For example, the reflective surface 573 can be microetched to create, for example, a larger surface area, roughness, and/or ridges to enhance deflection/scattering of light. Alternatively, the reflective surface 573 can be microetched to smooth the reflective surface 573, thereby improving the concentration of light and improving the uniformity of the backlighting of the interferometric modulator array.

In one embodiment, the one or more reflective elements comprise a material having a substantially flat or planar structure and micro-roughness, wherein the reflective element material may be deposited and formed in one or more layers by a process including, for example, etching, thermal annealing, and/or radiation curing. Micro-roughness may be formed by micro-etching, controlling the deposition process, and/or the properties of the material.

In other embodiments, one or more of the reflective elements 572 comprises a substantially optically transmissive material and a plurality of reflective particles suspended in the transmissive material. The reflective particles preferably comprise a material configured to reflect and/or scatter incident light. As noted above, the one or more reflective elements may have a unitary structure, such as a continuous layer, and/or the reflective elements may comprise a plurality of discrete structures. In some embodiments, the reflective layer may comprise a substantially grid-like pattern.

The position and configuration (e.g., shape) of the reflective element 572 can be controlled to optimize its efficacy in directing light into the interferometric modulator cavity 584. In some embodiments, the light reflecting element 572 can be located directly below the optical aperture area 574, although the reflecting element can be located elsewhere.

In one embodiment, the reflective element 572 is sufficiently wide and shaped to reflect substantially all light from the backlight 575 and passing through the aperture region 574 into the cavity 584 of the interferometric modulator array element 525. In some embodiments, the width of the reflective element 572 may vary depending on the size of the angular distribution of light from the backlight 575 and passing through the aperture region 574. For a non-collimated backlight (i.e., passing through the aperture over a wide range of angles), the size of the reflective element 572 may vary with the distance of the aperture area from the reflective element 572. This distance can be determined by, for example, the thickness of the upper mirror 571, the spacing between the mirror 571 and the reflective element 572. The width (w) of the aperture region 574 may also be a factor in addition to the angular range of light incident through the aperture region. The reflective element can be smaller if the light passes through the aperture 574 at a limited range of angles.

In one embodiment, the width of reflective element 572 is substantially greater than the width w of aperture region 574, and preferably greater than 3 w. In one embodiment, reflective elements 572 extend a distance of at least w beyond the corresponding aperture region 574.

A too wide reflective element 572, while effectively blocking stray light, may reduce the size of the pixel area available for the reflective state. Thus, there is a balance between selecting a wide reflective element to deflect more light and the area of the pixel where the interferometric modulator element 525 is available for the reflective state. Reflective element 572 can have a width of about 1 micron to about 10 microns. In other embodiments, reflective element 572 can have a profile with a greater or lesser width.

Reflective element 572 can have a height of between about 200 and about 1000 angstroms, although the height can be outside of this range. The heights may also be varied so that different portions of the reflective element 572 at different locations around an interferometric modulator 525, or at different locations in the array 550, have different heights.

Reflective element 572 preferably comprises one or more reflective materials and may comprise, for example, at least one of aluminum, silver, titanium, gold, and copper. Other materials may be used. The reflective element 572 may be a specular reflective optical element or a diffuse reflective optical element.

As described above, the reflective element 572 is formed over the substrate 554, between the substrate and the interferometric modulator element 525. Substrate 554 may have a thickness of, for example, about 200 microns to about 2 millimeters, or about 2 millimeters to about 5 millimeters, or may be larger or smaller. The reflective element 572 is covered with a layer of substantially optically transmissive material, such as a planarizing material 582. This layer may have a thickness of, for example, about 1 micron. The spacing between mirror 571 and reflective element 572, as described above, is related to the thickness of planarization material 582. Other materials may be used in alternative embodiments.

One or more interferometric modulator elements 525, each of which includes an optical cavity 584, are formed on the planarizing material 582. The interferometric modulator elements 525 comprise an optical stack 583 formed on a planarization material 582, wherein the optical stack 583 comprises an electrode layer 580, a metal layer 578 (e.g., chromium), and a dielectric or oxide layer 576. The electrode layer 580 comprises a conductive material, such as tin indium oxide (ITO), or zinc oxide (ZnO), for example, and may be substantially optically transmissive or partially transmissive. The metal layer 578 can comprise a reflective material, such as chromium. Other metals may also be used. In various embodiments, the electrode layer 580 has a thickness sufficient to be electrically conductive and the metal layer 578 may have a thickness sufficient to be partially reflective. Electrode layer 580 and metal layer 578 can, for example, have a thickness of about 100 angstroms to about 1 micron, and dielectric layer 576 can have a thickness of about 100 to 2,000 angstroms. In some embodiments, the dielectric layer may further comprise a multilayer dielectric optical film. Other configurations are possible. For example, certain layers may be removed and additional layers may be used. Additionally, in other embodiments, the thickness may be outside of the ranges.

The mechanical layer 570 supports a mirror 571, metal, and dielectric layers 580, 578, 576 on the electrodes to form a cavity 584, as described above. Other configurations are possible. As described above, in certain embodiments, the mechanical layer 570 and the mirror 571 comprise one or more optically transmissive aperture regions configured to enable light from the backlight 575 to pass therethrough and into the cavity of a corresponding interferometric modulator element. Also, the electrode 580 and/or the metal layer 578 may comprise a substantially transmissive material and/or may comprise a plurality of substantially transmissive apertures to allow light reflected from one or more reflective elements to be transmitted into a cavity of an interferometric modulator element. These devices will be discussed in more detail below.

The reflective element 572 can be formed using a number of methods known in the art, and a number of exemplary methods will be further discussed below with respect to FIGS. 9A-9C, which show a number of exemplary reflective element structures and configurations. In the embodiment shown in FIG. 9A, reflective element 572 comprises a shaped device, such as a bump 702, formed from a matrix material, such as a polymer. This shaped device 702 is covered with a cover layer 704 comprising a reflective material, such as aluminum. The aluminum layer 704 may reflect light having a wavelength in the visible range, for example. Other reflective materials than aluminum may be used, such as silver, titanium, gold, or copper. A layer of base material may be deposited and patterned to form bumps 702 or other desired shapes. A layer of reflective material 704 may be deposited on the polymer base material to form a reflective coating.

In the embodiment shown in fig. 9B, substrate 554 is etched to form a cavity 706 having a substantially rectangular cross-section. A reflective element 572 is formed within cavity 706 by depositing a reflective material, such as a metal. A substantially convex geometry may be formed, for example, within cavity 706. In one embodiment, the cavity has a substantially convex surface therein, and a substantially convex geometry is formed by depositing reflective material on said convex surface within the cavity. Other geometries are possible.

In the embodiment shown in FIG. 9C, a substantially concave cavity 708 is formed in the substrate 554 and a layer of reflective material is deposited within the cavity 708 to form a substantially concave reflective element 572. Alternatively, concave or convex surface features may be formed on the substrate that are not within the cavities (e.g., by etching the substrate), and a reflective material may be deposited on such shaped surface features. As noted above, the reflective element structures, geometries, and locations shown and discussed herein are exemplary only, and other structures, geometries, and locations are not excluded. Exemplary methods of forming a reflective element as described above may include material deposition, etching, thermal annealing, radiation curing, and combinations thereof.

As described with respect to fig. 8B, the reflective element 572 can be covered with a planarizing material having a thickness of about (e.g.) 1 micron. The planarization material may be applied using methods such as spin-on deposition. Several optically transmissive spin-on deposition materials are available. Many of these materials can be "hot-milled" to form a transparent silicon oxide material. These spin-on deposition materials are available from Dow Corning corporation, MI, Midland, and Clariant Life Sciences k.k. of tokyo, japan. The planarizing material can also be a material such as photoresist. After the planarization material is formed, the surface of the planarization material may be planarized using a planarization process, such as chemical mechanical polishing. Alternatively, other materials than planarization materials may be utilized, and multiple layers may be used.

FIG. 10 shows an embodiment of a reflective element 572 for an interferometric modulator array in which a masking device or mask is used to hide the reflective element 572 from view. In one embodiment, a mask 802 is formed on a glass substrate 554 and covered with a substantially transparent layer 804. A reflective element 572 is then formed over the transparent mask 802. Preferably, mask 802 comprises a material configured to hide the presence of reflective element 572. The mask 802 may be transparent or translucent. The mask 802 may comprise an absorptive material, a reflective material, a transmissive material, or a combination thereof, and may comprise materials such as chromium (Cr), molybdenum (Mo), carbon black, dyes, and the like. For example, in some embodiments, the mask 802 may comprise a photoresist material (e.g., spin-on photoresist), polyimide, photo-amide, inorganic polymer, and/or polymeric material that is either inherently substantially optically absorptive or reflective, or may comprise materials such as carbon particles (e.g., carbon black), metal particles, fillers, and/or dyes therein such that the mask 802 is substantially optically absorptive or reflective in the visible spectrum. In certain embodiments, the material(s) are selected and included in mask 892 in an amount effective to impart a black appearance to the resulting substantially optically absorptive support structure. Changes may also be made to the design.

In one embodiment, mask 802 comprises an aligner or a portion of an aligner. Specifically, one embodiment of mask 802 comprises a first partially reflective/partially transmissive layer, such as a metal layer comprising, for example, chromium, and at least one layer of cavity or spacer material, such as an oxide or planarization material, to form an etalon comprising a first reflective (e.g., metal) layer and reflective elements 572. In another embodiment, the mask 802 further comprises a second reflective layer between the spacer material and the reflective element 572, wherein the first reflective layer and the second reflective layer under the reflective element 572 form an aligner. The first and/or second collimator reflective layers may comprise the same material as the metal layer 578 in the optical stack 583. In certain embodiments, the etalon produces a predetermined color on the visible or viewing side of the interferometric modulator array and masks undesired devices.

As described above, the interferometric modulator array 500 may be efficiently illuminated using backlighting. In some embodiments, the light is collimated so that the light from the backlight 575 has a limited range of angles. Preferably, the light is directed straight between the backlight 575 and the array 500. The range of acceptable angles may depend on a combination of feature sizes. For example, if the aperture width (w) is 10 microns, the width of the reflective element is 30 microns, and the distance between the mirror 571 and the reflective element 572 is 1 micron, light of steep angles (large angles relative to the normal of the substrate) will be blocked, while other light will be reflected. The light may be collimated in several ways depending on the choice of backlight. For example, some backlight configurations may be provided that limit the emitted light to a particular range of angles. Lenses or other collimating optics may be used. The backlight 575 may also use a filter or other optical film to remove light at extreme angles.

The reflective element 572 will propagate the collimated light from the backlight 575 to the adjacent interferometric modulator. Since light will reflect from the reflective element at many different angles, light will be provided from a single reflective element to several interferometric modulators. Light for a single interferometric modulator may also come from a plurality of reflective elements. However, the light provided by the backlight does not necessarily have to comprise collimated light.

An SEM image of another embodiment of an interferometric modulator array is shown in FIG. 11. In the interferometric modulator array 500, the mechanical layer 570 is patterned to form a plurality of aperture regions 574 surrounding each interferometric modulator element 525. The narrow portions of the electrode layer 570 at the corners of the modulator elements 525 provide electrical connections between the interferometric modulators, such as interferometric modulators along a row. These narrow portions of the electrode layer 570 are arranged adjacent to the post structure 599 shown in fig. 11. A plurality of optically transmissive aperture regions 574 enable light to propagate to a reflective element (not shown), such as described above.

FIGS. 12A and 12B are system block diagrams illustrating one embodiment of a display device 2040. The display device 2040 can be, for example, a cellular or mobile telephone. However, the same components of display device 2040 and slight variations thereof are also illustrative of various types of display devices such as televisions and portable media players.

The display device 2040 includes a housing 2041, a display 2030, an antenna 2043, a speaker 2045, an input device 2048, and a microphone 2046. The housing 2041 is typically made by any of a number of manufacturing processes well known to those skilled in the art, including injection molding and vacuum forming. Further, the housing 2041 may be made from any of a wide variety of materials, including but not limited to plastic, metal, glass, rubber, and ceramic, or a combination thereof. In one embodiment, the housing 2041 includes removable portions (not shown) that can be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols.

The display 2030 of exemplary display device 2040 may be any of a wide variety of displays, including a bi-stable display as described herein. In other embodiments, the display 2030 comprises a flat panel display, such as a plasma, EL, OLED, STN LCD, or TFT LCD as described above, or a non-flat panel display, such as a CRT or other tube device, as is well known to those skilled in the art. However, for purposes of describing the present embodiment, the display 2030 includes an interferometric modulator display, as described herein.

The components of one embodiment of exemplary display device 2040 are schematically shown in figure 12B. The exemplary display device 2040 shown includes a housing 2041 and may include other components at least partially enclosed therein. For example, in one embodiment, the exemplary display device 2040 includes a network interface 2027, and the network interface 2027 includes an antenna 2043 coupled to a transceiver 2047. The transceiver 2047 is connected to the processor 2021, which processor 2021 is in turn connected to conditioning hardware 2052. Conditioning hardware 2052 may be configured to condition a signal (e.g., filter a signal). Conditioning hardware 2052 is coupled to a speaker 2045 and a microphone 2046. The processor 2021 is also connected to an input device 2048 and a driver controller 2029. The driver controller 2029 is coupled to a frame buffer 2028 and to the array driver 2022, which in turn is coupled to a display array 2030. A power supply 2050 provides power to all components as required by the design of the particular exemplary display device 2040.

The network interface 2027 includes the antenna 2043 and the transceiver 2047 so that the exemplary display device 2040 can communicate with one or more devices over a network. In one embodiment, the network interface 2027 may also have some processing functions to reduce the requirements on the processor 2021. The antenna 2043 is any antenna known to those skilled in the art for transmitting and receiving signals. In one embodiment, the antenna transmits and receives RF signals according to the IEEE802.11 standard, including IEEE802.11 (a), (b), or (g). In another embodiment, the antenna transmits and receives RF signals according to the BLUETOOTH (BLUETOOTH) standard. In the case of a cellular telephone, the antenna is designed to receive CDMA, GSM, AMPS or other conventional signals used to communicate in a wireless mobile telephone network. The transceiver 2047 pre-processes the signals received from the antenna 2043 so that they may be received by and further processed by the processor 2021. The transceiver 2047 also processes signals received from the processor 2021 so that they may be transmitted from the exemplary display device 2040 via the antenna 2043.

In an alternative embodiment, the transceiver 2047 may be replaced by a receiver. In yet another alternative embodiment, the network interface 2027 can be replaced by an image source, which can store or generate image data to be sent to the processor 2021. For example, the image source can be a Digital Video Disc (DVD) or a hard-disc drive that contains image data, or a software module that generates image data.

The processor 2021 generally controls the overall operation of the exemplary display device 2040. The processor 2021 receives data, such as compressed image data, from the network interface 2027 or an image source and processes the data into raw image data or into a format that is readily processed into raw image data. The processor 2021 then sends the processed data to the driver controller 2029 or to frame buffer 2028 for storage. Raw data generally refers to information that identifies the image characteristics at each location within an image. For example, these image characteristics may include color, saturation, and gray-scale level.

In one embodiment, the processor 2021 includes a microprocessor, CPU, or logic unit to control operation of the exemplary display device 2040. Conditioning hardware 2052 typically includes amplifiers and filters for sending signals to the speaker 2045, and for receiving signals from the speaker 2046. Conditioning hardware 2052 may be discrete components within the exemplary display device 2040 or may be incorporated within the processor 2021 or other components.

The driver controller 2029 receives raw image data generated by the processor 2021 either directly from the processor 2021 or from the frame buffer 2028 and reformats the raw image data appropriately for high speed transmission to the array driver 2022. In particular, the driver controller 2029 reformats the raw image data into a data flow having a raster-like format, such that it has a time order suitable for scanning the display array 2030. The driver controller 2029 then sends the formatted information to the array driver 2022. Although a driver controller 2029, such as an LCD controller, is typically associated with the system processor 2021 as a stand-alone Integrated Circuit (IC), such controllers may be implemented in a number of ways. They may be embedded in the processor 2021 as hardware, embedded in the processor 2021 as software, or fully integrated in hardware with the array driver 2022.

Typically, the array driver 2022 receives the formatted information from the driver controller 2029 and reformats the video data into a parallel set of waveforms that are applied many times per second to the hundreds and sometimes thousands of leads coming from the display's x-y array of pixels.

In one embodiment, the driver controller 2029, array driver 2022, and display array 2030 are appropriate for any of the types of displays described herein. For example, in one embodiment, the driver controller 2029 is a conventional display controller or a bi-stable display controller (e.g., an interferometric modulator controller). In another embodiment, the array driver 2022 is a conventional driver or a bi-stable display driver (e.g., an interferometric modulator display). In one embodiment, a driver controller 2029 is integrated with the array driver 2022. Such embodiments are common in highly integrated systems such as cellular phones, watches, or other small area displays. In yet another embodiment, the display array 2030 is a typical display array or a bi-stable display array (e.g., a display including an array of interferometric modulators).

The input device 2048 enables a user to control the operation of the exemplary display device 2040. In one embodiment, input device 2048 includes a keypad (e.g., a QWERTY keyboard or a telephone keypad), a button, a switch, a touch-sensitive screen, a pressure-or heat-sensitive membrane. In one embodiment, the microphone 2046 is an input device for the exemplary display device 2040. In entering data to the device using the microphone 2046, voice commands may be provided by a user to control the operation of the exemplary display device 2040.

The power supply 2050 can include a variety of energy storage devices, as are well known in the art. For example, in one embodiment, power supply 2050 is a rechargeable battery, such as a nickel-cadmium battery or a lithium ion battery. In another embodiment, power supply 2050 is a renewable energy source, a capacitor, or a solar cell, including plastic solar cells and solar-cell paint. In another embodiment, power supply 2050 is configured to receive power from a wall outlet.

In some implementations, control programmability resides, as described above, in a driver controller that can be located in multiple locations in an electronic display system. In some cases, control programmability exists in the array driver 2022. Those skilled in the art will appreciate that the above-described optimization may be implemented in any number of hardware and/or software components in different configurations.

Although spatial light modulators comprising arrays of interferometric modulator elements are described above, in other embodiments, other types of light modulating elements comprising light modulating arrays may be used. For example, other types of MEMS structures may be used in other embodiments. Other types of structures that are not based on MEMS technology may also be used in some embodiments.

It will be understood by those skilled in the art that various modifications may be made without departing from the spirit of the invention. Accordingly, it should be clearly understood that the forms of the present invention are illustrative only and are not intended to limit the scope of the present invention.

Claims (56)

1. An apparatus, comprising:

a light modulating array comprising a plurality of light modulating elements, each light modulating element of the plurality of light modulating elements having a cavity defined by first and second optical surfaces, the second optical surface being movable relative to the first optical surface;

at least one optical aperture region in the light modulating array; and

at least one reflective element formed between a substrate and the plurality of light modulation elements and configured to receive light passing through the optical aperture region and reflect at least a portion of the received light to the cavity.

2. The apparatus of claim 1, wherein the at least one optical aperture region is located at a substantially centered position in the light modulating array.

3. The device of claim 1, wherein the at least one reflective element comprises at least one of aluminum, silver, titanium, gold, and copper.

4. The apparatus of claim 1, wherein the at least one reflective element has an inclined surface.

5. The apparatus of claim 1, wherein the at least one reflective element has a substantially convex geometry.

6. The apparatus of claim 1, wherein the at least one reflective element has a substantially concave geometry.

7. The device of claim 1, further comprising a mask aligned with the at least one reflective element to at least partially obscure a line of sight of the at least one reflective element.

8. The apparatus of claim 7, wherein the mask comprises at least a portion of an aligner.

9. The device of claim 8, wherein the portion of the collimator comprises one or more layers of partially reflective, partially transmissive material and one or more spacer layers.

10. The apparatus of claim 1, wherein the at least one reflective element comprises at least one shaping device and a reflective material on the shaping device.

11. The device of claim 1, wherein the substrate of the light modulating array comprises at least one cavity, and wherein the at least one reflective element is formed within the cavity of the substrate.

12. The device of claim 1, wherein the at least one reflective element comprises interconnected portions to form a continuous unitary structure extending adjacent to a plurality of light modulation elements.

13. The device of claim 1, wherein the plurality of light modulating elements comprise a metal layer, and wherein the metal layer has a plurality of optically transmissive apertures.

14. The apparatus of claim 1, wherein at least some of the light modulating elements are separated from each other to form an optical aperture region therebetween.

15. The apparatus of claim 1, wherein the at least one reflective element comprises a substantially granular reflective material suspended in a substantially transparent material.

16. The device of claim 1, further comprising:

a processor in electrical communication with the plurality of light modulation elements, the processor configured to process image data; and

a memory device in electrical communication with the processor.

17. The device of claim 16, further comprising:

a drive circuit configured to send at least one signal to the plurality of light modulation elements.

18. The device of claim 17, further comprising:

a controller configured to send at least a portion of the image data to the drive circuit.

19. The device of claim 16, further comprising:

an image source module configured to send the image data to the processor.

20. The device of claim 19, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

21. The device of claim 16, further comprising:

an input device configured to receive input data and to communicate the input data to the processor.

22. A method of manufacturing a spatial light modulator, comprising:

forming at least one reflective element on a substrate; and

forming a plurality of light modulating elements on the substrate over the at least one reflective element to form a light modulating array having at least one optically transmissive aperture region, each light modulating element comprising first and second optical surfaces for defining a cavity, the second optical surface being movable relative to the first optical surface,

wherein the at least one reflective element is configured to receive light passing through the at least one aperture region and reflect at least a portion of the received light into the cavity.

23. The method of claim 22, wherein forming the at least one reflective element comprises depositing at least one of aluminum, silver, titanium, gold, and copper.

24. The method of claim 22, wherein forming the at least one reflective element comprises forming a substantially slanted surface.

25. The method of claim 22, wherein forming the at least one reflective element comprises forming a substantially convex geometry.

26. The method of claim 22, wherein forming the at least one reflective element comprises forming a substantially concave geometry.

27. The method of claim 22, wherein the at least one reflective element is formed on a layer of material formed on the substrate.

28. The method of claim 22, further comprising forming a masking device on the substrate in alignment with the at least one reflective element to mask the visual presence of the at least one reflective element.

29. The method of claim 28, wherein the masking device comprises a mask formed of at least one of an absorptive material and a reflective material.

30. The method of claim 28, wherein the masking device comprises a masking layer formed from at least one of a carbon black material, a dye, chromium, and molybdenum.

31. The method of claim 28, wherein the masking device comprises a metal film to form an aligner comprising the metal film and the at least one reflective element.

32. The method of claim 31, wherein the collimator has a thickness that causes the collimator to reflect one color.

33. The method of claim 22, wherein forming the at least one reflective element comprises forming a shaped base structure on the substrate and depositing a reflective material on the shaped base structure.

34. The method of claim 22, further comprising forming a cavity in the substrate and forming the at least one reflective element substantially in the cavity of the substrate.

35. The method of claim 22, wherein forming the at least one reflective element comprises depositing a layer of reflective material on the substrate and surface treating the layer.

36. The method of claim 22, wherein forming the at least one reflective element comprises depositing a composite material on the substrate surface, wherein the composite material comprises reflective particles suspended in a substantially transparent material.

37. The method of claim 36, wherein the composite material is deposited at discrete locations on the substrate surface to form a plurality of reflective elements.

38. A spatial light modulator made by the method of any of claims 22 to 37.

39. A method of backlighting an array of interferometric modulators, comprising:

activating a light source proximate a first side of the array of interferometric modulators; and

light from the light source is reflected to a second opposing side of the interferometric modulator array using one or more reflective elements located between a substrate and a plurality of interferometric modulator elements formed on the substrate.

40. The method of claim 39, wherein the light is reflected using a plurality of discrete reflective elements.

41. The method of claim 39, wherein the light is reflected using one or more reflective elements having a slanted surface.

42. The method of claim 39, wherein the light is reflected with one or more convex reflective elements.

43. The method of claim 39, wherein the light is reflected with one or more concave reflective elements.

44. The method of claim 39, wherein the light is reflected with one or more reflective elements comprising at least one of aluminum, silver, titanium, gold, and copper.

45. The method of claim 39, wherein the light is reflected with one or more reflective elements, and wherein the method further comprises obscuring the one or more reflective elements to be hidden from view.

46. The method of claim 45, further comprising forming at least a portion of an aligner between the one or more reflective elements and a viewer to implement the masking.

47. A display, comprising:

means for modulating light, disposed on a substrate;

means for generating light proximate a first side of the means for modulating light; and

means for reflecting the light from a location between a substrate and the means for modulating light formed on the substrate to a second opposing side of the means for modulating light.

48. The display of claim 47, wherein said means for modulating light comprises a plurality of interferometric modulator elements forming at least a portion of an interferometric modulator array.

49. The display of claim 48, wherein said reflecting means comprises a plurality of discrete reflective elements.

50. The display of claim 49, further comprising means for obscuring said discrete reflective elements from view.

51. The display of claim 50, wherein said masking means comprises means for forming at least a portion of an aligner between said one or more reflective elements and a viewer.

52. The display of claim 48, wherein said reflecting means comprises one or more reflecting elements having inclined surfaces.

53. A display as claimed in claim 48, in which the reflective means comprises one or more convex reflective elements.

54. A display as claimed in claim 48, in which the reflective means comprises one or more concave reflective elements.

55. The display of claim 48, wherein said reflective means comprises one or more reflective elements comprising at least one of aluminum, silver, titanium, gold, and copper.

56. The display of claim 47, wherein said means for generating light comprises at least one of a light emitting diode, a fluorescent lamp, and an incandescent lamp.