Method and device for a display having transparent components integrated therein

A display panel includes an array of interferometric modulators arranged over a transparent substrate and a transparent electrical device arranged between the array of interferometric modulators and the transparent substrate. The transparent electrical device may be electrically connected to the array of interferometric modulators or to other parts of the display panel. Examples of suitable transparent electrical devices include capacitors, resistors, inductors and filters. The use of such transparent electrical devices may provide various advantages, such as increased design flexibility, by allowing the electrical devices to be included in various parts of the array, including the viewing regions.

BACKGROUND

1. Field of the Invention

The field of the invention relates to microelectromechanical systems (MEMS).

2. Description of the Related Technology

Microelectromechanical systems (MEMS) include micro mechanical elements, actuators, and electronics. Micromechanical elements may be created using deposition, etching, 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 MEMS device is called an interferometric modulator. As used herein, the term interferometric modulator or interferometric light modulator refers to a device that selectively absorbs and/or reflects light using the principles of optical interference. In certain embodiments, 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. In a particular embodiment, one plate may comprise a stationary layer deposited on a substrate and the other plate may comprise a metallic membrane separated from the stationary layer by an air gap. As described herein in more detail, the position of one plate in relation to another can change the optical interference of light incident on the interferometric modulator. 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 features can be exploited in improving existing products and creating new products that have not yet been developed.

SUMMARY

The systems, methods, and devices described herein each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this invention, its more prominent features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description of the Preferred Embodiments” one will understand how the various embodiments described herein provide advantages over other methods and display devices.

An embodiment provides a display panel that includes an array of interferometric modulators arranged over a transparent substrate, and a transparent electrical device arranged between the array of interferometric modulators and the transparent substrate, the transparent electrical device being electrically connected to the array of interferometric modulators.

Another embodiment provides a display device that includes a substrate that includes an array region, an interferometric modulator attached to the substrate in the array region, and a transparent passive electrical device attached to the substrate in the array region.

Another embodiment provides a method of making a display device. The method includes forming a transparent electrical device on a substrate, depositing an insulating layer over the transparent electrical device, forming an interferometric modulator over the insulating layer, and forming an electrical connection between the transparent electrical device and the interferometric modulator.

These and other embodiments are described in greater detail below.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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 this 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 embodiments 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 particularly, it is contemplated that the embodiments may be implemented in or associated with a variety of electronic devices such as, but not limited to, mobile telephones, wireless devices, personal data assistants (PDAs), hand-held 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., odometer 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 structure to those described herein can also be used in non-display applications such as in electronic switching devices.

An embodiment provides a display panel in which transparent electrical devices are arranged between a substrate and an array of interferometric modulators. Examples of suitable transparent electrical devices include capacitors, resistors, inductors and filters. The use of such transparent electrical devices may provide various advantages, such as increased design flexibility, by allowing the electrical devices to be included in various parts of the array, including the viewing regions.

One interferometric modulator display embodiment comprising an interferometric MEMS display element is illustrated inFIG. 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 a 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.

The depicted portion of the pixel array inFIG. 1includes two adjacent interferometric modulators12aand12b.In the interferometric modulator12aon the left, a movable and highly reflective layer14ais illustrated in a relaxed position at a predetermined distance from a fixed partially reflective layer16a.In the interferometric modulator12bon the right, the movable highly reflective layer14bis illustrated in an actuated position adjacent to the fixed partially reflective layer16b.

The fixed layers16a,16bare 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 onto a transparent substrate20. The layers are patterned into parallel strips, and may form row electrodes in a display device as described further below. The movable layers14a,14bmay be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes16a,16b) deposited on top of posts18and an intervening sacrificial material deposited between the posts18. When the sacrificial material is etched away, the deformable metal layers14a,14bare separated from the fixed metal layers by a defined gap19. A highly conductive and reflective material such as aluminum may be used for the deformable layers, and these strips may form column electrodes in a display device.

With no applied voltage, the cavity19remains between the layers14a,16aand the deformable layer is in a mechanically relaxed state as illustrated by the pixel12ainFIG. 1. However, when a potential difference is applied 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 is deformed and is forced against the fixed layer (a dielectric material which is not illustrated in this Figure may be deposited on the fixed layer to prevent shorting and control the separation distance) as illustrated by the pixel12bon the right inFIG. 1. The behavior is the same regardless of the polarity of the applied potential difference. In this way, 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.

FIGS. 2 through 4illustrate one exemplary process and system for using an array of interferometric modulators in a display application.

FIG. 2is a system block diagram illustrating one embodiment of an electronic device that may incorporate aspects of the invention. In the exemplary embodiment, the electronic device includes a processor21which may be any general purpose single- or multi-chip microprocessor such as an ARM, Pentium®, Pentium II®, Pentium III®, Pentium IV®, Pentium® Pro, an 8051, a MIPS®, a Power PC®, an ALPHA®, or any special purpose microprocessor such as a digital signal processor, microcontroller, or a programmable gate array. As is conventional in the art, the processor21may 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 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 row1electrode, 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 row2electrode, actuating the appropriate pixels in row2in accordance with the asserted column electrodes. The row1pixels are unaffected by the row2pulse, and remain in the state they were set to during the row1pulse. This may be repeated for the entire series of rows in a sequential fashion to produce the frame. Generally, the frames are refreshed and/or updated with new display data by continually repeating this 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.

FIGS. 3B and 4Aillustrate one possible actuation protocol for creating a display frame on the 3×3 array ofFIG. 2.FIG. 3Billustrates a possible set of column and row voltage levels that may be used for pixels exhibiting the hysteresis curves ofFIG. 3A. In theFIG. 3Bembodiment, actuating a pixel involves setting the appropriate column to −Vbias, and the appropriate row to +ΔV, which may correspond to −5 volts and +5 volts respectively Relaxing the pixel is accomplished by setting the appropriate column to +Vbias, and the appropriate row to the same +ΔV, producing a zero volt potential difference across the pixel. In those rows where the row voltage is held at zero volts, the pixels are stable in whatever state they were originally in, regardless of whether the column is at +Vbias, or −Vbias. As is also illustrated inFIG. 3B, it will be appreciated that voltages of opposite polarity than those described above can be used, e.g., actuating a pixel can involve setting the appropriate column to +Vbias, and the appropriate row to −ΔV. In this embodiment, releasing the pixel is accomplished by setting the appropriate column to −Vbias, and the appropriate row to the same −ΔV, producing a zero volt potential difference across the pixel.

FIG. 4Bis a timing diagram showing a series of row and column signals applied to the 3×3 array ofFIG. 2which will result in the display arrangement illustrated inFIG. 4A, where actuated pixels are non-reflective. Prior to writing the frame illustrated inFIG. 4A, the pixels can be in any state, and in this example, all the rows are at 0 volts, and all the columns are at +5 volts. With these applied voltages, all pixels are stable in their existing actuated or relaxed states.

In theFIG. 4Aframe, pixels (1,1), (1,2), (2,2), (3,2) and (3,3) are actuated. To accomplish this, during a “line time” for row1, columns1and2are set to −5 volts, and column3is set to +5 volts. This does not change the state of any pixels, because all the pixels remain in the 3-7 volt stability window. Row1is then strobed with a pulse that goes from 0, up to 5 volts, and back to zero. This actuates the (1,1) and (1,2) pixels and relaxes the (1,3) pixel. No other pixels in the array are affected. To set row2as desired, column2is set to −5 volts, and columns1and3are set to +5 volts. The same strobe applied to row2will then actuate pixel (2,2) and relax pixels (2,1) and (2,3). Again, no other pixels of the array are affected. Row3is similarly set by setting columns2and3to −5 volts, and column1to +5 volts. The row3strobe sets the row3pixels as shown inFIG. 4A. After writing the frame, the row potentials are zero, and the column potentials can remain at either +5 or −5 volts, and the display is then stable in the arrangement ofFIG. 4A. It will be appreciated that the same procedure can be employed for arrays of dozens 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 systems and methods described herein.

FIGS. 5A and 5Bare system block diagrams illustrating an embodiment of a display device40. The display device40can be, for example, a cellular or mobile telephone. However, the same components of display device40or slight variations thereof are also illustrative of various types of display devices such as televisions and portable media players.

The display device40includes a housing41, a display30, an antenna43, a speaker44, an input device48, and a microphone46. The housing41is generally formed from any of a variety of manufacturing processes as are well known to those of skill in the art, including injection molding, and vacuum forming. In addition, the housing41may be made from any of a variety of materials, including but not limited to plastic, metal, glass, rubber, and ceramic, or a combination thereof. In one embodiment the housing41includes removable portions (not shown) that may be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols.

The display30of exemplary display device40may be any of a variety of displays, including a bi-stable display, as described herein. In other embodiments, the display30includes a flat-panel display, such as 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 of skill in the art. However, for purposes of describing the present embodiment, the display30includes an interferometric modulator display, as described herein.

The components of one embodiment of exemplary display device40are schematically illustrated inFIG. 5B. The illustrated exemplary display device40includes a housing41and can include additional components at least partially enclosed therein. For example, in one embodiment, the exemplary display device40includes a network interface27that includes an antenna43which is coupled to a transceiver47. The transceiver47is connected to a processor21, which is connected to conditioning hardware52. The conditioning hardware52may be configured to condition a signal (e.g. filter a signal). The conditioning hardware52is connected to a speaker44and a microphone46. The processor21is also connected to an input device48and a driver controller29. The driver controller29is coupled to a frame buffer28, and to an array driver22, which in turn is coupled to a display array30. A power supply50provides power to all components as required by the particular exemplary display device40design.

The network interface27includes the antenna43and the transceiver47so that the exemplary display device40can communicate with one ore more devices over a network. In one embodiment the network interface27may also have some processing capabilities to relieve requirements of the processor21. The antenna43is any antenna known to those of skill in the art for transmitting and receiving signals. In one embodiment, the antenna transmits and receives RF signals according to the IEEE 802.11 standard, including IEEE 802.11(a), (b), or (g). In another embodiment, the antenna transmits and receives RF signals according to the BLUETOOTH standard. In the case of a cellular telephone, the antenna is designed to receive CDMA, GSM, AMPS or other known signals that are used to communicate within a wireless cell phone network. The transceiver47pre-processes the signals received from the antenna43so that they may be received by and further manipulated by the processor21. The transceiver47also processes signals received from the processor21so that they may be transmitted from the exemplary display device40via the antenna43.

In an alternative embodiment, the transceiver47can be replaced by a receiver. In yet another alternative embodiment, network interface27can be replaced by an image source, which can store or generate image data to be sent to the processor21. 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.

Processor21generally controls the overall operation of the exemplary display device40. The processor21receives data, such as compressed image data from the network interface27or an image source, and processes the data into raw image data or into a format that is readily processed into raw image data. The processor21then sends the processed data to the driver controller29or to frame buffer28for 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.

In one embodiment, the processor21includes a microcontroller, CPU, or logic unit to control operation of the exemplary display device40. Conditioning hardware52generally includes amplifiers and filters for transmitting signals to the speaker44, and for receiving signals from the microphone46. Conditioning hardware52may be discrete components within the exemplary display device40, or may be incorporated within the processor21or other components.

The driver controller29takes the raw image data generated by the processor21either directly from the processor21or from the frame buffer28and reformats the raw image data appropriately for high speed transmission to the array driver22. Specifically, the driver controller29reformats 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 array30. Then the driver controller29sends the formatted information to the array driver22. Although a driver controller29, such as a LCD controller, is often associated with the system processor21as a stand-alone Integrated Circuit (IC), such controllers may be implemented in many ways. They may be embedded in the processor21as hardware, embedded in the processor21as software, or fully integrated in hardware with the array driver22.

Typically, the array driver22receives the formatted information from the driver controller29and 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 matrix of pixels.

In one embodiment, the driver controller29, array driver22, and display array30are appropriate for any of the types of displays described herein. For example, in one embodiment, driver controller29is a conventional display controller or a bi-stable display controller (e.g., an interferometric modulator controller). In another embodiment, array driver22is a conventional driver or a bi-stable display driver (e.g., an interferometric modulator display). In one embodiment, a driver controller29is integrated with the array driver22. Such an embodiment is common in highly integrated systems such as cellular phones, watches, and other small area displays. In yet another embodiment, display array30is a typical display array or a bi-stable display array (e.g., a display including an array of interferometric modulators).

The input device48allows a user to control the operation of the exemplary display device40. In one embodiment, input device48includes a keypad, such as a QWERTY keyboard or a telephone keypad, a button, a switch, a touch-sensitive screen, a device for the exemplary display device40. When the microphone46is used to input data to the device, voice commands may be provided by a user for controlling operations of the exemplary display device40.

Power supply50can include a variety of energy storage devices as are well known in the art. For example, in one embodiment, power supply50is a rechargeable battery, such as a nickel-cadmium battery or a lithium ion battery. In another embodiment, power supply50is a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell, and solar-cell paint. In another embodiment, power supply50is configured to receive power from a wall outlet.

In some implementations control programmability resides, as described above, in a driver controller which can be located in several places in the electronic display system. In some cases control programmability resides in the array driver22. Those of skill in the art will recognize that the above-described optimization may be implemented in any number of hardware and/or software components and in various configurations.

The details of the structure of interferometric modulators that operate in accordance with the principles set forth above may vary widely. For example,FIGS. 6A-6Cillustrate three different embodiments of the moving mirror structure.FIG. 6Ais a cross section of the embodiment ofFIG. 1, where a strip of metal material14is deposited on orthogonally extending supports18. InFIG. 6B, the moveable reflective material14is attached to supports at the corners only, on tethers32. InFIG. 6C, the moveable reflective material14is suspended from a deformable layer34. This embodiment has benefits because the structural design and materials used for the reflective material14can be optimized with respect to the optical properties, and the structural design and materials used for the deformable layer34can be optimized with respect to desired mechanical properties. The production of various types of interferometric devices is described in a variety of published documents, including, for example, U.S. Published Application 2004/0051929. A wide variety of known techniques may be used to produce the above described structures involving a series of material deposition, patterning, and etching steps.

As illustrated inFIGS. 1 and 2and discussed above, each cavity19of the pixel array30forms a capacitance that is charged by the row driver circuit24. The capacitance value is relatively large for any particular actuated pixel12bbecause the column electrode14bmoves to be very close to the row electrode16b.Because different numbers of cavities may be actuated during a given row pulse, that impedance that the row driver circuitry sees may be highly variable.

FIG. 7illustrates an embodiment in which filter circuits325a,325b,325care arranged over a substrate20between the row electrodes16a,16b,16cand the row driver circuit24. It has been found that such filter circuits325a,325b,325care useful for controlling the impedance driven by the row driver circuit24. For example, such filter circuits325a,325b,325cmay be used to control the stability of the impedance or to allow the impedance to be modifiable for different row pulses. In the illustrated embodiment, each of the filter circuits325a,325b,325cincludes a capacitor328a,328b,328cand a resistor329a,329b,329c,respectively. The filter circuits325a-c,capacitors328a-c,and resistors329a-care examples of electrical devices that may be incorporated into the pixel array30. Other examples of electrical devices include inductors (not shown inFIG. 7). For example, in an embodiment, a filter includes at least one capacitor, at least one resistor and at least one inductor. Such electrical devices may be incorporated in various regions of the pixel array30and may be used for various purposes. For example, electrical devices such as filter circuits, capacitors, resistors, and/or inductors may be arranged between the column driver circuit26and the column electrodes14(not shown inFIG. 7). AlthoughFIG. 7illustrates a 3×3 array30of interferometric modulators, it will be understood that display panels or devices as described herein may comprise arrays that include hundreds, thousands or even millions of individual interferometric modulators.

In an embodiment, the electrical devices may be incorporated into the pixel array30at or near an edge or a peripheral region36of the substrate20. However, in some cases incorporation of the electrical devices at or near the peripheral region36of the substrate20is inconvenient or undesirable. For example, capacitors having relatively large capacitance values may be utilized in certain arrangements. Such capacitors may have relatively large capacitor plate areas and/or may be used in relatively large numbers, and thus may occupy commensurately large areas at or near the peripheral region36of the substrate20, in some cases reducing the area of the substrate20that is available for the pixel array30.

Various embodiments described herein provide a display device that includes one or more transparent electrical devices that may be incorporated at various locations within the device, including locations within the same region or footprint of the substrate as occupied by the array, particularly between the substrate20and the pixel array30. Thus, for example, the designer of a display device that includes interferometric modulators need not be constrained to place electrical devices such as filters, resistors, capacitors and inductors only at or near the edges of the device. Instead, various embodiments allow increased design flexibility by providing transparent electrical devices that may be included in viewing regions of the device.

It will be understood that a “transparent” electrical device need not transmit 100% of incident radiation at all visible wavelengths. An electrical device is considered “transparent” if, when incorporated into a viewing region of a display device, it is capable of transmitting sufficient incident radiation to permit the device to function in a generally similar or improved manner as compared to an otherwise similar device that does not include the transparent electrical device in the viewing region. In many cases, the transparent electrical device transmits at least about 80% of incident optical irradiation, more preferably at least about 90%. It follows from the foregoing that it is not necessary for all of the materials used to fabricate the transparent electrical device be transparent per se themselves. For example, various materials (such as metals) may be used in such small amounts, and/or be deposited in such thin layers, and/or be dispersed so finely in another material, that transparency is achieved, even in cases in which the bulk material is not ordinarily considered transparent per se.

Various electrical devices are described herein, including filters, resistors, capacitors and inductors. Unless otherwise stated, as used herein those terms have their ordinary meanings as understood by those skilled in the art. For example, a capacitor may be a storage capacitor. Examples of preferred capacitors include those having a capacitance in the range of about 10 picoFarad to about 0.1 microFarad. Examples of preferred resistors include those having a resistance in the range of about 100 Ohms to about one gigaOhm. Examples of preferred inductors include those having an inductance in the range of about one nanoHenry to about 10 microHenry. Each of the electrical devices described herein may be used singly, in groups or two or more like devices, or in groups comprising two or more devices that are different, in all of the embodiments described below. Likewise, it will be understood that various features, though illustrated in the context of a particular embodiment, may also be utilized in other embodiments.

An embodiment provides a display panel comprising an array of interferometric modulators arranged over a transparent substrate, and a transparent electrical device arranged between the array of interferometric modulators and the transparent substrate, the transparent electrical device being electrically connected to the array of interferometric modulators. The transparent electrical device may be a passive electrical device such as a capacitor, resistor, inductor and/or filter. It will be understood that the transparent electrical device may include various combinations of individual electrical components. For example, a filter may include a resistor and a capacitor as illustrated inFIG. 7.

FIG. 8Ais a cross-sectional schematic view illustrating a display panel or device embodiment800. The display panel800includes an interferometric modulator805arranged over a transparent substrate20. The display panel800further includes a transparent capacitor815arranged between the interferometric modulator805and the transparent substrate20. The interferometric modulator805is similar to the interferometric modulator12bdescribed above, and includes a moveable layer14b(shown in the actuated position), a fixed layer16b,and posts18. The interferometric modulator805also includes a dielectric layer820arranged over the fixed layer16bto prevent shorting and control the separation distance between the moveable layer14band the fixed layer16bin the actuated position. The dielectric layer820may be formed from a dielectric material such as a silicon oxide. The fixed layer16bpreferably comprises sublayers (not illustrated) of chromium and indium-tin-oxide (ITO), and the moveable layer14bpreferably comprises aluminum. The interferometric modulator805is viewed through the transparent substrate20, and thus the transparent substrate20is considered to be on the view side of the display panel800. Accordingly, the thickness of the fixed layer16bis selected so that it is transparent during operation of the display panel800.

InFIG. 8A, the transparent capacitor815is separated from the fixed layer16bof the interferometric modulator805by a transparent insulating layer825. The transparent insulating layer may comprise a silicon oxide. The transparent capacitor815comprises a first capacitor layer830and a second capacitor layer835, separated from one another by a capacitor dielectric layer840. The first and second capacitor layers830,835are preferably formed from a transparent electrical conductor such as ITO. The capacitor dielectric layer840preferably comprises a transparent dielectric material such as silicon oxide (k˜4.1). Contacts (not shown) electrically connect the transparent capacitor815to the array generally (e.g., to the overlying interferometric modulator805and/or other interferometric modulators in the array) and to other circuitry, such as drivers.

As noted above, in the illustrated embodiment the transparent substrate20is considered to be on the view side of the display panel800. Thus, the transparent capacitor815is an example of a transparent passive electrical device configured to transmit light to the interferometric modulator805from the viewing side of the transparent substrate20. In the illustrated configuration, both the transparent capacitor815and the interferometric modulator805are attached (directly or indirectly) to the substrate20in the array region of the display device into which they are incorporated.

FIG. 8Bis a cross-sectional schematic view illustrating a display panel embodiment850. The display panel is similar to the display panel800except that it includes a filter325in place of the capacitor815illustrated inFIG. 8A. The filter325includes a capacitor815aand a resistor329. The capacitor815ais similar to the capacitor815illustrated inFIG. 8Ain that both comprise a first capacitor layer830and a second capacitor layer835. However, in the capacitor815a,the first and second capacitor layers830,835are separated from one another by a capacitor dielectric layer840athat includes a transparent resistor329. The transparent resistor329electrically connects the first and second capacitor layers830,835. In the illustrated embodiment, the transparent resistor329has a resistance of about 10 kΩ.

In other embodiments, including those in which the resistor is not attached to a capacitor and/or those in which the display panel does not include a capacitor, the resistor has a resistance in the range of about 100 Ohms to about one gigaOhm as noted above. The resistor may comprise a transparent insulator (such as a transparent polymer or a silicon oxide) that has been doped with an amount of electrically conductive material (such as a metal) that is effective to provide the resulting resistor with a resistance that is intermediate between that of the insulator and the conductor.

FIG. 9is a schematic perspective view illustrating an inductor embodiment900. The inductor900comprises a generally spiral conductor910that is connected to a second conductor920. The generally spiral conductor910is formed in a first plane905and the second conductor920is formed in a second plane915that is generally parallel to the first plane905. The generally spiral conductor910is connected to the second conductor920via a transverse conductor912that is generally perpendicular to the first plane905and the second plane915. The inductor900may be formed by methods known to those skilled in the art. For example, the plane905may comprise a transparent substrate onto which a transparent conductive metal such as ITO is deposited and patterned into a generally spiral shape. The second plane915may comprise a layer of insulating material such as a silicon oxide that is deposited over the first plane905using known methods. A via may then be formed through the second plane915to the second conductor920and then filled with a conducting metal such as ITO to form the transverse conductor912. The second conductor920may then be formed by depositing and patterning a transparent metal such as ITO on the second plane915to contact the transverse conductor912. Other methods known to those skilled in the art may also be used, see, e.g., U.S. Pat. Nos. 6,531,945; 6,249,039; and 6,166,422. An inductor such as the inductor900may be incorporated into a display panel in a manner similar to that described above forFIGS. 8A and 8B.

It will be understood that display panel embodiments800,850include additional interferometric modulators (not shown inFIGS. 8A and 8B) that are preferably organized in an array30, e.g., as illustrated inFIG. 7. The transparent electrical device in the display panel (e.g., the capacitor815and the filter325) may be operably connected to the array of interferometric modulators in various ways. In an embodiment, the transparent capacitor815is electrically connected to the array of interferometric modulators by electrically connecting the second capacitor layer835to the fixed layer16band by electrically connecting the first capacitor layer830to the row driver circuit24as illustrated inFIG. 7. The row driver circuit24on the periphery of the substrate20or off the substrate20. Such electrical connections may be accomplished in various ways. For example, with reference toFIGS. 8A and 8B, the second capacitor layer835may be electrically connected to the fixed layer16bby, e.g., forming a via in the transparent insulating layer825, filling the via with an electrically conducting material such as a metal, then depositing a thin layer of ITO over the transparent insulating layer825and the filled-in via to form the fixed layer16b,such that the electrically conducting material in the filled-in via forms an electrical connection between the second capacitor layer835and the fixed layer16b.

It will be understood that the electrical connections from the transparent capacitor815to the array may be made in various ways, and that the transparent capacitor815may be connected to a plurality of interferometric modulators. For example, the fixed layer16bmay form a row line for multiple interferometric modulators in an array as illustrated inFIG. 7. The electrical connection of the second capacitor layer835to the fixed layer16bmay be made at various places along the length of the fixed layer16b.The transparent filter325may be electrically connected to the array of interferometric modulators in a similar manner.

It will be understood from the foregoing that a particular transparent electrical device in an array of interferometric modulators may be, but need not be, electrically connected to the individual interferometric modulator that is closest to it. Likewise, it will also be understood that a particular transparent electrical device need not be electrically connected to an interferometric modulator. For example, a particular transparent electrical device may be electrically connected to another device that is associated (e.g., packaged or mechanically connected) with the array of interferometric modulators. An embodiment provides a display device comprising: a substrate comprising an array region; an interferometric modulator attached to the substrate in the array region; and a transparent passive electrical device attached to the substrate in the array region. Examples of suitable transparent passive electrical devices include filters, resistors, capacitors and inductors as described above. The transparent passive electrical device(s) may be located in various parts of the array region, such as between an interferometric modulator and the substrate, or may be formed in the periphery. In an embodiment, one or more of the transparent passive electrical device are configured to transmit light to one or more interferometric modulators from a viewing side of the substrate in the array region. Examples of such configurations are described above and illustrated inFIGS. 8A and 8B.

Another embodiment provides a method of making a display device, comprising: forming a transparent electrical device on a substrate; depositing an insulating layer over the transparent electrical device; forming an interferometric modulator over the insulating layer; and forming an electrical connection between the transparent electrical device and the interferometric modulator.FIG. 10is a process flow diagram illustrating certain steps in such a method. Each of the steps illustrated inFIG. 10may be conducted in various ways known to those skilled in the art of MEMS fabrication. For example, a wide variety of techniques are known to those skilled in the art, including chemical vapor deposition (including plasma chemical vapor deposition and thermal chemical vapor deposition), spin-on deposition, lithography, etching, patterning, cleaning, soldering, and packaging techniques.

In an embodiment, transparent electrical devices are formed by a combination of chemical vapor deposition, patterning and removal steps. Formation of a transparent electrical device preferably comprises depositing a conductive layer and a dielectric layer, e.g., depositing the first capacitor layer830and the capacitor dielectric layer840as described above. Formation of the transparent electrical device may further comprise patterning, e.g., patterning a deposited capacitor dielectric layer840to define a region to be removed and filled with the transparent resistor329to form the capacitor dielectric layer840aas illustrated inFIG. 8B.

Deposition of an insulating layer over the transparent electrical device may be carried out by, e.g., chemical vapor deposition of silicon oxide; chemical vapor deposition of silicon followed by oxidation to form silicon oxide; or by a spin-on glass (SOG) process. The details of such methods are known to those skilled in the art. Formation of an interferometric modulator over the insulating layer may be conducted in various ways, depending on the configuration of the interferometric modulator, see, e.g.,FIG. 6. The previously deposited insulating layer is a suitable substrate upon which to form an interferometric modulator, as a number of known processes for making interferometric modulators involve deposition steps onto glass substrates.

There are numerous methods for forming electrical connections between the transparent electrical device and the interferometric modulator. For example, as described above, the second capacitor layer835may be electrically connected to the fixed layer16bby forming a via in the transparent insulating layer825prior to forming the interferometric modulator, filling the via with an electrically conducting material such as a metal, then depositing a thin layer of ITO over the transparent insulating layer825and the filled-in via to form the fixed layer16b,such that the electrically conducting material in the filled-in via forms an electrical connection between the second capacitor layer835and the fixed layer16b.Lateral electrical connections may be formed by deposition and patterning using a conductive metal.