HK1103806A - System and method of implementation of interferometric modulators for display mirrors - Google Patents

Abstract

CN101027590A A specular interferometric modulator array is configured to be at least partially selectably reflective. As such, the array forms a mirror surface having the capability of displaying information to the user while simultaneously being used as a specular mirror. The displayed information may be based on information from an external source, may be programmable, and may be based on user input.

Description

System and method for implementing interferometric modulators for display mirrors

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. provisional application No. 60/613,298 entitled "System and Method for Implementation of interactive Modulator display", filed on 9/27/2004, the entire contents of which are incorporated herein by reference.

Technical Field

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

Background

Microelectromechanical Systems (MEMS) include micromechanical 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 referred to as 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 in greater detail herein, the position of one plate relative to another can change the optical interference of light on the interferometric modulator. These 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.

Disclosure of Invention

The system, method, and apparatus of the present invention 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 certain embodiments" one will understand how the features of this invention provide advantages over other display devices.

One embodiment includes a device comprising a substrate and an array of reflective elements arranged on the substrate to form at least a portion of a specular surface that specularly and interferometrically reflects light in at least one wavelength band. One or more of the elements are configured to be selectably reflective.

Another embodiment includes a device that includes means for conducting light and means for specularly and interferometrically reflecting light in at least one wavelength band. The specular and interferometric light reflecting means are arranged on the conducting means, and at least a portion of the specular interferometric light reflecting means is configured to selectively reflect.

Another embodiment includes a vehicle including a steering mechanism and a mirror configured to be positioned such that light from behind the vehicle is reflected to a location for an operator to see when the operator is positioned to use the steering mechanism. The mirror includes a substrate and an array of reflective elements arranged on the substrate to form a mirror surface that specularly and interferometrically reflects light in at least one wavelength band.

Another embodiment includes a vehicle including means for steering and means for reflecting light from behind the vehicle to a location for an operator to see when the operator is positioned to use the steering means. The reflecting means includes means for conducting light and means for specularly and interferometrically reflecting light in at least one wavelength band. The specularly interferometrically reflecting means is arranged on the conducting means, and at least a portion of the specularly interferometrically reflecting means is configured to be selectively reflected. The specularly and interferometrically light reflecting means are arranged on the conducting means, and at least a portion of the specularly and interferometrically light reflecting means is configured to be selectively reflected.

Another embodiment includes a device comprising a mirror comprising: a substrate; and an array of reflective elements arranged on the substrate to form a specular surface that specularly and interferometrically reflects light in at least one wavelength band; and a mount configured to attach the mirror to a vehicle, a wall, a piece of furniture, an ornament, a piece of clothing, or a person.

Another embodiment includes a device comprising means for reflecting light, the means for reflecting light comprising: a member for conducting light; and means for specularly and interferometrically reflecting light in at least one wavelength band; and means for attaching the reflective member to a vehicle, a wall, an article of furniture, an ornament, an article of clothing, or a person.

Another embodiment includes a method of using a display device including establishing a communication link between the device and an information source. The device includes a mirror including elements configured to selectably, specularly and interferometrically reflect light; and a mount configured to attach the mirror to a vehicle, a wall, an article of furniture, an ornament, an article of clothing, or a person. The method also includes receiving information from the source and displaying the information on an array.

Another embodiment includes a method of manufacturing a device. The method includes forming a substrate, and forming an array of reflective elements arranged on the substrate so as to produce a specular surface that specularly and interferometrically reflects light in at least one wavelength band. One or more of the elements are configured to be selectably reflective.

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 relaxed 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 incorporating a 33 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 an illustration of a set of row and column voltages that may be used to drive an interferometric modulator display.

FIGS. 5A and 5B illustrate one exemplary timing diagram for row and column signals that may be used to write a frame of display data to the 33 interferometric modulator display of FIG. 2.

FIGS. 6A and 6B are system block diagrams illustrating an embodiment of a visual display device comprising a plurality of interferometric modulators.

Fig. 7A is a cross-section of the device of fig. 1.

FIG. 7B is a cross section of an alternative embodiment of an interferometric modulator.

FIG. 7C is a cross section of another alternative embodiment of an interferometric modulator.

FIG. 7D is a cross section of yet another alternative embodiment of an interferometric modulator.

FIG. 7E is a cross section of an additional alternative embodiment of an interferometric modulator.

FIG. 8 is a front view of an interferometric device configured as a specularly reflective display that can provide information to a viewer.

Fig. 9 is a front view of a rear view mirror embodiment.

Detailed Description

The following detailed description is directed to certain specific embodiments of the invention. However, the invention can be embodied in many different forms. In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout. It will be appreciated from the following description that 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 having structures similar to those described herein may also be used in non-display applications such as electronic switching devices.

One interferometric modulator display embodiment comprises an array of MEMS display elements, at least a portion of which is substantially specular and at least a portion of which is selectively reflective. The mirrored portion of the display may be used as a mirror and the selectively reflective portion may be used to display information. This allows information to be displayed on the device while the device is simultaneously used as a mirror, for example while driving, combing or making up.

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

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 may be moved between two positions. In the first position, referred to herein as the relaxed position, the movable reflective layer is positioned at a relatively large distance from a fixed partially reflective layer. In the second position, referred to herein as the actuated position, the movable reflective layer is positioned more closely adjacent 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 depicted portion of the pixel array in FIG. 1 includes two adjacent interferometric modulators 12a and 12 b. In the interferometric modulator 12a on the left, a movable reflective layer 14a is illustrated in a relaxed position at a predetermined distance from an optical stack 16a, which includes a partially reflective layer. In the interferometric modulator 12b on the right, the movable reflective layer 14b is illustrated in an actuated position adjacent to the optical stack 16 b.

The optical stacks 16a and 16b (collectively referred to as optical stack 16), as referenced herein, typically include several fused layers (fused layers) that may include an electrode layer, such as Indium Tin Oxide (ITO), a partially reflective layer, such as chromium, and a transparent dielectric. Thus, the optical stack 16 is electrically conductive, partially transparent and partially reflective, and may be fabricated, for example, by depositing one or more of the above layers onto a transparent substrate 20. In certain embodiments, the layers are patterned into parallel strips, and may form row electrodes in a display device, as described further below. The movable reflective layers 14a, 14b may be formed as a series of parallel strips (perpendicular to the row electrodes 16a, 16 b) of a deposited metal layer(s) deposited on top of posts 18 and an intervening sacrificial material deposited between the posts 18. When the sacrificial material is etched away, the movable reflective layers 14a, 14b are separated from the optical stacks 16a, 16b by defined gaps 19. A highly conductive and reflective material such as aluminum may be used for the reflective layer 14, and these strips may form column electrodes in a display device.

With no applied voltage, the cavity 19 remains between the movable reflective layer 14a and optical stack 16a, with the movable reflective layer 14a in a mechanically relaxed state, as illustrated by the pixel 12a in FIG. 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 reflective layer 14 is deformed and is forced against the optical stack 16. A dielectric layer (not shown in this figure) within the optical stack 16 may prevent shorting and control the separation distance between layers 14 and 16, as illustrated by pixel 12b on the right in fig. 1. Behaves the same regardless of the polarity of the applied potential difference. In this manner, 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. 2-5 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 incorporate 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 (e.g., ARM, Pentium)^®、Pentium II^®、Pentium III^®、Pentium IV^®、Pentium^® Pro、8051、MIPS^®、Power PC^®、ALPHA^®) Or any special purpose microprocessor (e.g., 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 also configured to communicate with an array driver 22. In one embodiment, the array driver 22 includes a row driver circuit 24 and a column driver circuit 26 that provide signals to a panel or display array (display) 30. The cross-section of the array illustrated in FIG. 1 is shown by the lines 1-1 in FIG. 2. For MEMS interferometric modulators, the row/column actuation protocol may take advantage of the hysteresis characteristics of these devices illustrated in FIG. 3. A potential difference of, for example, 10 volts may be required to cause a movable layer to deform from the relaxed state to the actuated state. However, when the voltage is reduced from that value, the movable layer maintains its state as the voltage drops back below 10 volts. In the exemplary embodiment of FIG. 3, the movable layer does not relax completely until the voltage drops below 2 volts. There is thus a range of voltage, about 3 to 7V in the example illustrated in fig. 3, where there is a window of applied voltage within which the device is stable in either the relaxed or actuated state. This window 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 may be designed such that during row strobing, pixels in the strobed row that are to be actuated are exposed to a voltage difference of about 10 volts, and pixels that are to be relaxed are exposed to a voltage difference of near zero volts. 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. In this example, each pixel sees a potential difference within the "stability window" of 3-7 volts after being written. This feature makes the pixel design illustrated in fig. 1 stable under the same applied voltage conditions in either an actuated or relaxed pre-existing state. Because each pixel of the interferometric modulator, whether in the actuated or relaxed state, is essentially a capacitor formed by the fixed and moving reflective layers, this stable state can be maintained at a voltage within the hysteresis window with almost no power dissipation. Essentially, if the applied voltage is fixed, no current flows into the pixel.

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 set of asserted 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 remain in the state they were set to during the row 1 pulse. This process may be repeated for the entire series of rows in a sequential manner to produce a frame. Typically, 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 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 illustrate one possible activation protocol for forming display frames on the 3 x 3 array of fig. 2. FIG. 4 illustrates a possible set of column and row voltage levels that may be used for pixels exhibiting the hysteresis curves of FIG. 3. In the FIG. 4 embodiment, actuating a pixel involves setting the appropriate column to-V_biasAnd the appropriate row is set to + deltav, which may correspond to-5 volts and +5 volts, respectively. Relaxing the pixel is by setting the appropriate column to + V_biasAnd the appropriate row is set to the same + av, producing a zero volt potential difference across the pixel. In those rows where the row voltage is held at zero volts, regardless of whether the column is at + V_biasOr is-V_biasThe pixel is stable in whatever state it was originally in. As also illustrated in FIG. 4, 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 + V_biasAnd the appropriate row is set to- Δ V. In this embodiment, the pixel is released by setting the appropriate column to-V_biasAnd the appropriate row is set to the same-av, producing a zero volt potential difference across the pixel.

FIG. 5B is a timing diagram showing a series of row and column signals applied to the 3 x 3 array of FIG. 2 which will result in the display arrangement illustrated in FIG. 5A, wherein actuated pixels are non-reflective. Prior to writing the frame illustrated in FIG. 5A, 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 the frame of fig. 5A, pixels (1, 1), (1, 2), (2, 2), (3, 2), and (3, 3) are activated. To accomplish this, during a "line time" for row 1, columns 1 and 2 are set to-5 volts, and column 3 is set to +5 volts. This does not change the state of any pixels, since all pixels remain in the 3-7 volt stability window. Row 1 is then strobed with a pulse that goes from 0, up to 5 volts, and back to zero. This activates the (1, 1) and (1, 2) pixels and relaxes the (1, 3) pixel. 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. The same strobe applied to row 2 will then actuate pixel (2, 2) and relax pixels (2, 1) and (2, 3). Again, no other pixels of the array are affected. Row 3 is similarly 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 as shown in FIG. 5A. 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 of FIG. 5A. It will be appreciated that the same procedure can be used for arrays 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 systems and methods described herein.

Fig. 6A and 6B are system block diagrams illustrating an embodiment of a display device 40. The display device 40 may be, for example, a cellular or mobile telephone. However, the same components of display device 40 or slight variations thereof are also illustrative of various types of display devices such as televisions and portable media players.

The display device 40 includes a housing 41, a display 30, an antenna 43, a speaker 45, an input device 48, and a microphone 46. The housing 41 is generally formed from any of a variety of manufacturing processes well known to those skilled in the art, including injection molding and vacuum forming. Additionally, the housing 41 may be made from any of a variety of materials, including but not limited to plastic, metal, glass, rubber, and ceramic, or combinations thereof. In one embodiment, the housing 41 includes removable portions (not shown) that may be interchanged with other removable portions of different color, or containing different logos, pictures, or symbols.

As described herein, the display 30 of exemplary display device 40 may be any of a variety of displays, including a bi-stable display. In other embodiments, the display 30 includes 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 kinescope device, as is well known to those of skill in the art. However, for purposes of describing the present embodiment, the display 30 includes an interferometric modulator display, as described herein.

The components of one embodiment of exemplary display device 40 are schematically illustrated in FIG. 6B. The illustrated exemplary display device 40 includes a housing 41, and may include additional components at least partially enclosed in the housing 41. For example, in one embodiment, the exemplary display device 40 includes a network interface 27, the network interface 27 including an antenna 43 coupled to a transceiver 47. The transceiver 47 is connected to the processor 21, and the processor 21 is connected to the conditioning hardware 52. The conditioning hardware 52 may be configured to condition the signal (e.g., filter the signal). The conditioning hardware 52 is connected to a speaker 45 and a microphone 46. The processor 21 is also connected to an input device 48 and a driver controller 29. A driver controller 29 is coupled to a frame buffer 28 and to the array driver 22, which array driver 22 is in turn coupled to a display array 30. The power supply 50 provides power to all components as required by the particular exemplary display device 40 design.

The network interface 27 includes the antenna 43 and the transceiver 47 so that the exemplary display device 40 can communicate with one or more devices over a network. In one embodiment, the network interface 27 may also have some processing capabilities to relieve requirements of the processor 21. The antenna 43 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 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 cellular telephone network. The transceiver 47 pre-processes the signals received from the antenna 43 so that they may be received by and further processed by the processor 21. The transceiver 47 also processes signals received from the processor 21 so that they may be transmitted from the exemplary display device 40 via the antenna 43.

In an alternative embodiment, the transceiver 47 can be replaced by a receiver. In yet another alternative embodiment, network interface 27 can be replaced by an image source, which can store or generate image data to be sent to the processor 21. 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 21 generally controls the overall operation of the exemplary display device 40. The processor 21 receives data, such as compressed image data from the network interface 27 or an image source, and processes the data into raw image data or into a format that is readily processed into raw image data. The processor 21 then sends the processed data to the driver controller 29 or to frame buffer 28 for storage. Raw data generally refers to information that identifies the image features at each location within an image. These image characteristics may include color, saturation, and gray-scale level, for example.

In one embodiment, the processor 21 includes a microcontroller, CPU, or logic unit to control the operation of the exemplary display device 40. Conditioning hardware 52 generally includes amplifiers and filters for transmitting signals to the speaker 45, and for receiving signals from the microphone 46. Conditioning hardware 52 may be discrete components within the exemplary display device 40, or may be incorporated within the processor 21 or other components.

The driver controller 29 takes the raw image data generated by the processor 21 either directly from the processor 21 or from the frame buffer 28 and reformats the raw image data appropriately for high speed transmission to the array driver 22. Specifically, the driver controller 29 reformats the raw image data into a data flow having a raster-like format, such that it has a time order suitable for scanning across the display array 30. The driver controller 29 then sends the formatted information to the array driver 22. Although a driver controller 29, such as an LCD controller, is typically associated with the system processor 21 as a stand-alone Integrated Circuit (IC), such controllers may be implemented in many ways. They may be embedded in the processor 21 as hardware, embedded in the processor 21 as software, or fully integrated in hardware with the array driver 22.

Typically, the array driver 22 receives the formatted information from the driver controller 29 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 matrix of pixels.

In one embodiment, the driver controller 29, array driver 22, and display array 30 are suitable for any of the types of displays described herein. For example, in one embodiment, driver controller 29 is a conventional display controller or a bi-stable display controller (e.g., an interferometric modulator controller). In another embodiment, the array driver 22 is a conventional driver or a bi-stable display driver (e.g., an interferometric modulator display). In one embodiment, the driver controller 29 is integrated with the array driver 22. This embodiment is common in highly integrated systems such as cellular phones, watches, and other small area displays. In yet another embodiment, display array 30 is a typical display array or a bi-stable display array (e.g., a display including an array of interferometric modulators).

The input device 48 allows a user to control the operation of the exemplary display device 40. In one embodiment, input device 48 includes a keypad, such as 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 46 is an input device for the exemplary display device 40. When data is input to the device using the microphone 46, voice commands may be provided by a user for controlling operation of the exemplary display device 40.

The power supply 50 may include a variety of energy storage devices as are well known in the art. For example, in one embodiment, the power supply 50 is a rechargeable battery such as a nickel cadmium battery or a lithium ion battery. In another embodiment, power supply 50 is a renewable energy source, a capacitor, or a solar cell, including a plastic solar cell, and solar-cell paint. In another embodiment, power supply 50 is 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 driver 22. Those skilled in the art will appreciate 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. 7A-7E illustrate five different embodiments of the movable reflective layer 14 and its supporting structures. Fig. 7A is a cross-section of the embodiment of fig. 1, wherein a strip of metallic material 14 is deposited on vertically extending supports 18. In FIG. 7B, the movable reflective layer 14 is attached to supports at the corners only, on tethers (teters) 32. In FIG. 7C, the movable reflective layer 14 is suspended from a deformable layer 34, which may comprise a flexible metal. The deformable layer 34 is directly or indirectly connected to the substrate 20 around the perimeter of the deformable layer 34. These connections are referred to herein as struts. The embodiment illustrated in FIG. 7D has post plugs 42 upon which the deformable layer 34 rests. The movable reflective layer 14 remains suspended over the cavity, as in FIGS. 7A-7C, but the deformable layer 34 does not form the support posts by filling holes between the deformable layer 34 and the optical stack 16. Rather, the support posts are formed from a planarization material used to form the support post plugs 42. The embodiment illustrated in FIG. 7E is based on the embodiment shown in FIG. 7D, but may also be adapted to function with any of the embodiments illustrated in FIGS. 7A-7C, as well as additional embodiments not shown. In the embodiment shown in FIG. 7E, an additional layer of metal or other conductive material has been used to form the bus structure 44. This allows signal routing along the back of the interferometric modulators, eliminating many of the electrodes that may otherwise have had to be formed on the substrate 20.

In embodiments such as those shown in FIG. 7, the interferometric modulators function as direct-view devices, in which images are viewed from the front side of the transparent substrate 20, the side opposite to that upon which the modulator is arranged. In these embodiments, the reflective layer 14 optically shields some portions of the interferometric modulator, including the deformable layer 34 and the bus structure 44, on the side of the reflective layer opposite the substrate 20. This allows the shielded areas to be configured and operated upon without adversely affecting image quality. This separable modulator structure allows the structural design and materials used for the electromechanical aspects and the optical aspects of the modulator to be selected and to function independently of each other. Moreover, the embodiments shown in FIGS. 7C-7E have additional benefits arising from the decoupling of the optical properties of the reflective layer 14 from its mechanical properties, which are performed by the deformable layer 34. This allows the structural design and materials used for the reflective layer 14 to be optimized with respect to the optical properties, and the structural design and materials used for the deformable layer 34 to be optimized with respect to desired mechanical properties.

FIG. 8 shows an embodiment of a display device 125, the display device 125 comprising an array of interferometric modulators configured to be used substantially as mirror mirrors in addition to displaying information. At least a portion of the array may be configured to be specular (e.g., mirror-like) rather than scattering as is the case with many embodiments of interferometric modulators. Typically, interferometric modulators are mirror devices. In one modulator embodiment, the interferometric modulator exhibits scattering only when a scattering material is used to modulate incident and reflected light. When no scattering material is used, the array appears substantially specular. The reflective layer within the interferometric modulator is substantially specular, and the interferometric properties of the cavity and the optical stack may be configured such that the entire interferometric modulator is also specular. At least a portion of the array may be configured to be white (e.g., to reflect light over the visible spectrum) rather than colored (e.g., to reflect light within a narrow or broad band of visible wavelengths, or to reflect light within multiple narrow or broad bands of visible wavelengths but not the entire visible spectrum) as is the case with many embodiments of interferometric modulators. In addition to being substantially specular, the reflective layers within the interferometric modulator are also substantially white, and the interferometric properties of the cavity and the optical stack can be configured such that the entire interferometric modulator is also white. Techniques for achieving whiteness and specularity include, but are not limited to, those techniques discussed briefly herein. In general, if the optical stack is thin enough, it will not significantly change the whiteness of the device. The specific details will depend at least on the materials used. Certain embodiments of interferometric modulators having thin optical stacks have electronic control and mechanical structures on the side of the deflectable mirror opposite the optical stack. This allows the thickness of the optical stack to be controlled independently of the limitations caused when embedding the electrodes within the optical stack. Another option for whitening the device is to form an interferometric cavity with a gap large enough to allow multiple frequencies of light to constructively interfere.

In certain embodiments, at least a portion of the display device 125 may be configured to display information. As described above, the interferometric modulators in this portion may be configured to selectably change between at least two optical states according to an input. The optical properties of the at least two states are sufficiently different such that a contrast between the states is perceptible to a viewer. When the optical characteristics of the individual interferometric modulators are appropriately selected, information can be displayed. Optical characteristics that can be selectively varied include reflectance and color. For example, to display information, some interferometric modulators may be selected to have a higher reflectance than others, or some interferometric modulators may be selected to have a blue color and others have a green color, with the difference between the higher and lower reflectance and the blue and green colors being at least sufficient to be perceived by a viewer. Combinations of optical properties may be used. For example, the combination of color and reflectance can be varied to create a perceptible contrast. Other contrasting optical property states are possible and not useless. Thus, the ability to selectively change the contrast optical state of an interferometric modulator allows text or images to be displayed.

In certain embodiments, at least a portion of the display portion 120 can be configured to change between first and second optical states, while a second portion can be configured to change between third and fourth optical states. In some embodiments, the portions are continuous and large enough to be viewed by a viewer as distinct regions, each of which is perceived as having different optical characteristics. For example, a region may have the shape of the sun, and the interferometric modulators in that region may have color characteristics that reflect yellow light. Some of the interferometric modulators in the region may also selectably vary between reflecting yellow light and reflecting white light. Interferometric modulators that can be selectively varied can be used, for example, to display the current temperature.

In certain embodiments, the interferometric modulators may operate over a range of optical states (e.g., a continuous range of colors or gray levels or reflectivities), the display portion 120 may also be a color display, in which each pixel may selectively display a range of colors. The display portion 120 can also be displayed in a grayscale mode, where the interferometric modulators are configured to be white and how much the reflectance in each pixel varies according to the information to be displayed. The display device 125 may have various display portions 120, and the display portions 120 may each have different operating configurations as described above. In some embodiments, the operational configuration of the display portion may change.

As discussed above, in certain embodiments, information is displayed by the contrast of two optical states, both of which are reflective. In these embodiments, it should be noted that in addition to displaying information, the display portion 120 may also be specularly reflective, and will still act as a mirror. For example, if a portion of the display portion is displaying information using an interferometric modulator configured to change between orange and green reflective states, that portion of the display device 125 will still show an image of the object seen in the mirror. However, the objects will appear as if they are orange and/or green.

In certain embodiments, the display portion 120 may have interferometric modulators formed in a particular shape corresponding to the information or a portion of the information to be displayed. For example, the display portion 120 may have interferometric modulators in the shape of a vehicle with a door open. Such interferometric modulators may be used on rear view mirrors in vehicles. The door may not be fully closed by activating the interferometric modulator so as to have an appearance that contrasts with the surrounding area of the mirror. Certain interferometric modulators may be in the shape of a number field so as to be configured to display various numbers (in combination).

In some embodiments, a scattering material is applied to at least a portion of the array to make that portion of the display more scattering than other portions. For example, one or more portions of the device may be dedicated to only the display portion, where better display appearance may be obtained using scattering materials.

Alternatively, one or more portions may be dedicated to mirror only portions. In the mirror-only portion, the interferometric modulators may be configured to be in a single, non-selectable state having a white color as perceived by a viewer and/or having high reflectivity (i.e., having sufficient reflectivity to be effective as a mirror). The regions between the interferometric modulators may also be configured to have high reflectivity. In certain embodiments, only the mirror portion may include only the reflective layer, and may not include interferometric modulators. In certain embodiments, only the mirror portion may have optical stack characteristics tailored for high reflectivity.

Referring to fig. 8, the mirror surface 130 of the display device 125 may be used for any purpose for which a mirror is used, such as shaving or make-up. Meanwhile, the display portion 120 of the display device 125 may be used to provide information to the viewer. The display portion 120 may have any shape, may be located at any location of the display device 125, and may be moved from one location to another. Such manipulation of the display portion 120 may be controlled, for example, dynamically by user input or by programming or another external device. Although shown as rectangular in fig. 8, the display device 125 may have any shape.

The information may include any type of desired information including, but not limited to, news, stock quotes, sports scores, and the like. For example, when combing, information about weather forecasts can be displayed to help decide what clothing to wear the day. Information may be transferred to the display device 125 from an external source, such as, but not limited to, a telecommunications or display device, through a wired or wireless connection. For example, display device 125 may include or have a wired or wireless connection to a device having a television tuner, and the display may show morning news or a sporting event. The display device 125 may also include or have electrical connections to a PC or device for displaying video images, such as a video player or DVD player. In some embodiments, the PC may be connected to an internet site that presents live images (live images) of, for example, traffic conditions or places of interest in a natural environment such as a waterfall.

One or more aspects of the information may be programmable. The display device 125 may, for example, sequentially display the current ambient temperature, the predicted high temperature, and the predicted low temperature for the current day. The user may program the display device 125 to display one or more types of information from a set of selectable information types, such as sports scores, news headlines, or driving conditions. The information may be primarily aesthetic, such as decorative designs or pictures of the home. The information may be user defined, such as a "to do" list, or a reminder of a friend's birthday. The display device 125 may be configured to have various modes of operation from which a user may select. For example, a user may select a mode to display aesthetic images or to display traffic information or to display a combination of multiple information types.

User programmability can be managed in various ways. There may be a wireless or wired connection to a PC with software to program the display device 125. The display device 125 may include local processing capabilities using software to enable a user to graphically communicate with associated programming software. There may be an interface for a user to connect a keyboard and/or mouse to the display device 125, at least for programming. In some embodiments, the display device 125 may include touch screen technology, which may be used at least for programming. In some embodiments, the display device 125 may include buttons and/or knobs for programming and/or for controlling display characteristics (e.g., position or brightness).

In certain embodiments, the display device 125 is configured as a rear or side mirror on a vehicle. Such an embodiment is illustrated in fig. 9 as a rear view mirror 150. By using interferometric modulator technology, the mirror can display information to the driver. The information may include environmental information such as temperature, wind speed, and wind direction. Positioning data such as position, speed, and direction of travel may also be shown. Route information such as a map, a split segment display driving direction and direction of the next turn and distance to the next turn may be given. Vehicle status data such as speed, temperature, engine RPM, distance to objects behind the vehicle, images behind the vehicle may also be displayed. Radio information such as volume, channel, CD name, song name, and program name may also be displayed. Various warnings such as low fuel, high speed, high engine temperature, no seatbelt on passenger, low tire pressure, and proximity of external objects. Various sensors throughout the vehicle may be configured to communicate to the display device 125 to provide information to be displayed. Wireless connections may also be used to transfer information from external sources.

The mirror may also be configured with a mount to attach the mirror to a vehicle, a wall, a piece of furniture, an ornament, a piece of clothing, or a person.

While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the device or process illustrated may be made by those skilled in the art without departing from the spirit of the invention. As will be recognized, the present invention may be embodied within a form that does not provide all of the features and benefits set forth herein, as some features may be used or practiced separately from others.

Claims (71)

1. An apparatus, comprising:

a substrate; and

an array of reflective elements arranged on the substrate to form at least a portion of a specular surface that specularly and interferometrically reflects light in at least one wavelength band, wherein one or more of the elements are configured to be selectably reflective.

2. The device of claim 1, wherein one or more of the selectably reflective elements are configured to be selectably in one of first and second optical states.

3. The device of claim 2, wherein the first optical state differs from the second optical state in at least one of reflectance and color such that a contrast between the two states is perceptible to a viewer.

4. The device of claim 1, wherein one or more of the elements are configured to be in a single, non-selectable state that is highly reflective.

5. The device of claim 4, wherein at least a portion of an area between the elements that is configured to be in a single non-selectable state that is highly reflective is configured to be specularly reflective.

6. The device of claim 1, wherein at least a portion of a reflective surface of the mirror comprises a highly reflective layer configured to reflect non-interferometrically.

7. The device of claim 1, wherein at least one of the reflective elements of the array is formed in a shape corresponding to at least a portion of information to be displayed by the at least one element.

8. The device of claim 1, wherein at least a portion of an area between elements of the array is configured to specularly reflect.

9. The device of claim 1, wherein at least a first portion of the array comprises neighboring elements configured to be perceived by a viewer as displaying an optical characteristic different from an optical characteristic displayed by another portion of the array.

10. The device of claim 1, wherein at least one of the selectably reflective elements is configured to be perceived as:

displaying the information; and

is highly reflective.

11. The device of claim 1, wherein optical characteristics of one or more of the elements are based on at least one of input from an external source, user input, and programming.

12. The device of claim 1, wherein one or more of the elements are configured to be reflective across the visible spectrum.

13. The device of claim 1, wherein one or more of the elements are configured to reflect light substantially having a different wavelength band than one or more other elements.

14. The device of claim 1, further comprising:

a processor in electrical communication with the array, the processor configured to process image data; and

a memory device in electrical communication with the processor.

15. The device of claim 14, further comprising a driver circuit configured to send at least one signal to the array.

16. The device of claim 15, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

17. The device of claim 14, further comprising an image source module configured to send the image data to the processor.

18. The device of claim 17, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

19. The device of claim 14, further comprising an input device configured to receive input data and to communicate the input data to the processor.

20. An apparatus, comprising:

a member for conducting light; and

means for specularly and interferometrically reflecting light in at least one wavelength band, wherein the specularly and interferometrically reflecting means is arranged on the conducting means and at least a portion of the specularly and interferometrically reflecting means is configured to selectively reflect.

21. The apparatus of claim 20, wherein the conducting member comprises a substrate.

22. The device of claim 20 or 21, wherein the specularly and interferometrically reflecting means comprises an array of reflective elements forming at least a portion of a specular surface.

23. The device of claim 20, wherein at least a portion of the specularly and interferometrically reflecting means are configured to be in a single, non-selectable state that is highly reflective.

24. The device of claim 20, further comprising means for selecting an optical characteristic of a portion of selectable interferometric reflecting means based on at least one of input from an external source, user input, and programming.

25. The apparatus of claim 24, wherein the means for selecting comprises a driver circuit.

26. The device of claim 20, wherein a first portion of the selectably reflective means is configured to reflect light substantially having a different wavelength band than a second portion of the selectably reflective means.

27. A vehicle, comprising:

a steering mechanism; and

a mirror configured to be positioned such that light from behind the vehicle is reflected to a location for viewing by an operator when the operator is positioned to use the steering mechanism, the mirror comprising:

a substrate; and

an array of reflective elements arranged on the substrate to form a specular surface that specularly and interferometrically reflects light in at least one wavelength band.

28. The vehicle of claim 27, wherein the mirror is configured to display warnings, radio information, vehicle status data, route information, location data, or environmental information.

29. The vehicle of claim 27, wherein one or more of the reflective elements are configured to be selectably in one of first and second optical states.

30. The vehicle of claim 27, wherein one or more of the reflective elements are configured to be in a single, non-selectable state that is highly reflective.

31. The vehicle of claim 27, wherein at least a portion of a reflective surface of the mirror comprises a highly reflective layer configured to reflect non-interferometrically.

32. The vehicle of claim 27, wherein at least one of the reflective elements is formed in a shape corresponding to at least a portion of information to be displayed by the at least one element.

33. The vehicle of claim 27, wherein optical characteristics of one or more of the reflective elements are based on at least one of input from an external source, user input, and programming.

34. The vehicle of claim 27, further comprising:

a processor in electrical communication with the array, the processor configured to process image data; and

a memory device in electrical communication with the processor.

35. The vehicle of claim 34, further comprising a driver circuit configured to send at least one signal to the array.

36. The vehicle of claim 35, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

37. The vehicle of claim 34, further comprising an image source module configured to send the image data to the processor.

38. The vehicle of claim 37, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

39. The vehicle of claim 34, further comprising an input device configured to receive input data and to communicate the input data to the processor.

40. A vehicle, comprising:

a member for steering; and

means for reflecting light from behind the vehicle to a location for viewing by an operator when the operator is positioned to use the steering means, the reflecting means comprising:

a member for conducting light; and

means for specularly and interferometrically reflecting light in at least one wavelength band, wherein the specularly and interferometrically reflecting means is arranged on the conducting means and at least a portion of the specularly and interferometrically reflecting means is configured to selectively reflect.

41. The vehicle of claim 40, wherein the steering member comprises a steering mechanism.

42. A vehicle according to claim 40 or 41, wherein the means for reflecting light from behind the vehicle comprises a mirror.

43. A vehicle according to claim 40, 41 or 42, wherein the conductive member comprises a substrate.

44. The vehicle of claim 40, 41, 42 or 43, wherein the specularly and interferometrically reflecting means comprises an array of reflecting elements forming at least a portion of a specular surface.

45. An apparatus, comprising:

a mirror, comprising:

a substrate; and

an array of reflective elements arranged on the substrate to form a specular surface that specularly and interferometrically reflects light in at least one wavelength band; and

a mount configured to attach the mirror to a vehicle, a wall, an article of furniture, an ornament, an article of clothing, or a person.

46. The device of claim 45, wherein one or more of the elements are configured to be in a single, non-selectable state that is highly reflective.

47. The device of claim 45, wherein at least a first portion of the array comprises neighboring elements configured to be perceived by a viewer as displaying an optical characteristic different from an optical characteristic displayed by another portion of the array.

48. The device of claim 45, wherein optical characteristics of one or more of the elements are based on at least one of input from an external source, user input, and programming.

49. The device of claim 45, wherein one or more of the elements are configured to be reflective across the visible spectrum.

50. The device of claim 45, wherein one or more of the elements are configured to reflect light substantially having a different wavelength band than one or more other elements.

51. The device of claim 45, further comprising:

a processor in electrical communication with the array, the processor configured to process image data; and

a memory device in electrical communication with the processor.

52. The device of claim 51, further comprising a driver circuit configured to send at least one signal to the array.

53. The device of claim 52, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

54. The device of claim 51, further comprising an image source module configured to send the image data to the processor.

55. The device as recited in claim 54, wherein the image source module includes at least one of a receiver, transceiver, and transmitter.

56. The device of claim 51, further comprising an input device configured to receive input data and to communicate the input data to the processor.

57. An apparatus, comprising:

means for reflecting light, comprising:

a member for conducting light; and

means for specularly and interferometrically reflecting light in at least one wavelength band; and

means for attaching the reflective means to a vehicle, a wall, an article of furniture, an ornament, an article of clothing, or a person.

58. An apparatus as in claim 57, wherein the reflecting means comprises a mirror.

59. The apparatus of claim 57 or 58, wherein the conductive member comprises a substrate.

60. The device of claim 57, 58, or 59, wherein the specularly and interferometrically reflecting means comprises an array of reflecting elements forming at least a portion of a specular surface.

61. The device of claim 57, 58, 59 or 60, wherein the attachment member comprises a fastener.

62. A method of using a display device, comprising:

establishing a communication link between the apparatus and an information source, the apparatus comprising:

a mirror comprising elements configured to selectably, specularly and interferometrically reflect light; and

a mount configured to attach the mirror to a vehicle, a wall, an article of furniture, an ornament, an article of clothing, or a person;

receiving information from the source; and

displaying the information on the array.

63. The method of claim 62, wherein displaying the information comprises displaying the information based on at least one of input from an external source, user input, and programming.

64. The method of claim 62, wherein displaying the information comprises selecting a state for the element, wherein the element is configured to be selectably in one of first and second optical states.

65. The method of claim 64, wherein at least one of the elements for which a state is selected has a shape corresponding to at least a portion of information to be displayed by the at least one element.

66. The method of claim 62, wherein displaying the information comprises:

displaying a first optical characteristic on a first portion of the array; and

displaying a second optical characteristic on a second portion of the array.

67. A method of manufacturing a device, the method comprising:

forming a substrate; and

forming an array of reflective elements arranged on the substrate so as to produce a specular surface that specularly and interferometrically reflects light in at least one wavelength band, wherein one or more of the elements are configured to be selectably reflective.

68. The method of claim 67, wherein forming the array comprises configuring the elements to be selectably reflective based on at least one of input from an external source, programming, and user input.

69. The method of claim 67, wherein forming the array comprises configuring one or more of the elements to be reflective across the visible spectrum.

70. The method of claim 67, wherein forming the array comprises configuring one or more of the elements to reflect light substantially having a different wavelength band than one or more other elements.

71. An apparatus made by the method of claim 67.