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. An interferometric modulator may comprise a pair of conductive plates, one or both of which may be transparent and/or reflective in whole or part and capable of relative motion upon application of an appropriate electrical signal. One plate may comprise a stationary layer deposited on a substrate, the other plate may comprise a metallic membrane separated from the stationary layer by an air gap. Such devices have a wide range of applications, and it would be beneficial in the art to utilize and/or modify the characteristics of these types of devices so that their features can be exploited in improving existing products and creating new products that have not yet been developed.
The system, method, and devices of the 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 comprises a system having a central processing unit, a plurality of bi-stable display elements, and a driver controller. The driver controller is configured to receive video data from the central processing unit and display the video data independently of a frame buffer and via the plurality of bi-stable display elements.
Another embodiment comprises a central processing unit, a plurality of bi-stable display elements, and a driver controller. The driver controller is configured to receive video data from the central processing unit and display the video data via the plurality of bi-stable display elements independently of a predetermined refresh period.
Another embodiment comprises a central processing unit, a plurality of bi-stable display elements, and a driver controller. The driver controller is configured to receive video data from the central processing unit and display the video data via the plurality of bi-stable display elements at a dynamically modifiable refresh period.
Yet another embodiment comprises a system having an array of bi-stable display elements, a frame buffer, and a driver controller. The driver controller has a first interface and a second interface. In one embodiment, the driver controller is configured to store video data received via the first interface in the frame buffer. The driver controller transmits the video data received via the second interface directly to the array of bi-stable display elements. In one embodiment, a central processing unit is configured to provide video data for display by the array of bi-stable display elements. The central processing unit is configured to send the video data to the driver controller either via the first interface or the second interface.
Yet another embodiment comprises a method of displaying video data. The method comprises receiving video data and displaying, independently of a frame buffer, the received video data via an array of bi-stable display elements.
Yet another embodiment comprises a system for displaying video data. The system comprises: means for receiving video data and means for displaying, independently of a frame buffer, the received video data via an array of bi-stable display elements.
The following detailed description is directed to certain specific embodiments. However, the invention can be embodied in a multitude of different ways. Reference in this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrase “in one embodiment,” “according to one embodiment,” or “in some embodiments” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Moreover, various features are described which may be exhibited by some embodiments and not by others. Similarly, various requirements are described which may be requirements for some embodiments but not other embodiments.
In one embodiment, a display array on a device includes at least one driving circuit and an array of means, e.g., interferometric modulators, on which video data is displayed. Video data, as used herein, refers to any kind of displayable data, including pictures, graphics, and words, displayable in either static or dynamic images (for example, a series of video frames that when viewed give the appearance of movement, e.g., a continuous ever-changing display of stock quotes, a “video clip”, or data indicating the occurrence of an event of action). Video data, as used herein, also refers to any kind of control data, including instructions on how the video data is to be processed (display mode), such as frame rate, and data format. The array is driven by the driving circuit to display video data.
One embodiment comprises a driver controller having two interfaces for receiving video data. In one embodiment, video data that is transmitted to the first of the two interfaces is stored in a frame buffer. Video data that is transmitted to the second of the two interfaces is transmitted independently of the frame buffer and directly to an array driver for display. By limiting the usage of a frame buffer, potential power savings may be achieved. In one embodiment, a client device is manufactured to not include any frame buffer in order to further reduce manufacturing costs and obtain further power savings.
In this description, reference is made to the drawings wherein like parts are designated with like numerals throughout. The invention may be implemented in any device that is configured to display an image, whether in motion (e.g., video) or stationary (e.g., still image), and whether textual or pictorial. More particularly, it is contemplated that the invention 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.
Spatial light modulators used for imaging applications come in many different forms. Transmissive liquid crystal display (LCD) modulators modulate light by controlling the twist and/or alignment of crystalline materials to block or pass light. Reflective spatial light modulators exploit various physical effects to control the amount of light reflected to the imaging surface. Examples of such reflective modulators include reflective LCDs, and digital micromirror devices.
Another example of a spatial light modulator is an interferometric modulator that modulates light by interference. Interferometric modulators are bi-stable display elements which employ a resonant optical cavity having at least one movable or deflectable wall. Constructive interference in the optical cavity determines the color of the viewable light emerging from the cavity. As the movable wall, typically comprised at least partially of metal, moves towards the stationary front surface of the cavity, the interference of light within the cavity is modulated, and that modulation affects the color of light emerging at the front surface of the modulator. The front surface is typically the surface where the image seen by the viewer appears, in the case where the interferometric modulator is a direct-view device.
The network 3 can be operatively coupled to a broad variety of devices. Examples of devices that can be coupled to the network 3 include a computer such as a laptop computer 4, a personal digital assistant (PDA) 5, which can include wireless handheld devices such as the BlackBerry, a Palm Pilot, a Pocket PC, and the like, and a cell phone 6, such as a Web-enabled cell phone, Smartphone, and the like. Many other devices can be used, such as desk-top PCs, set-top boxes, digital media players, handheld PCs, Global Positioning System (GPS) navigation devices, automotive displays, or other stationary and mobile displays. For convenience of discussion all of these devices are collectively referred to herein as the client device 7.
One bi-stable display element embodiment comprising an interferometric MEMS display element is illustrated in
The depicted portion of the pixel array in
The partially reflective layers 16a, 16b are electrically conductive, partially transparent and fixed, and may be fabricated, for example, by depositing one or more layers each of chromium and indium-tin-oxide onto a transparent substrate 20. The layers are patterned into parallel strips, and may form row electrodes in a display device as described further below. The highly reflective layers 14a, 14b may be formed as a series of parallel strips of a deposited metal layer or layers (orthogonal to the row electrodes, partially reflective layers 16a, 16b) deposited on top of supports 18 and an intervening sacrificial material deposited between the supports 18. When the sacrificial material is etched away, the deformable metal layers are separated from the fixed metal layers by a defined air gap 19. 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 air gap 19 remains between the layers 14a, 16a and the deformable layer is in a mechanically relaxed state as illustrated by the interferometric modulator 12a in
Currently, available flat panel display controllers and drivers have been designed to work almost exclusively with displays that need to be constantly refreshed. Thus, the image displayed on plasma, EL, OLED, STN LCD, and TFT LCD panels, for example, will disappear in a fraction of a second if not refreshed many times within a second. However, because interferometric modulators of the type described above have the ability to hold their state for a longer period of time without refresh, wherein the state of the interferometric modulators may be maintained in either of two states without refreshing, a display that uses interferometric modulators may be referred to as a bi-stable display. In one embodiment, the state of the pixel elements is maintained by applying a bias voltage, sometimes referred to as a latch voltage, to the one or more interferometric modulators that comprise the pixel element.
In general, a display device typically requires one or more controllers and driver circuits for proper control of the display device. Driver circuits, such as those used to drive LCD's, for example, may be bonded directly to, and situated along the edge of the display panel itself. Alternatively, driver circuits may be mounted on flexible circuit elements connecting the display panel (at its edge) to the rest of an electronic system. In either case, the drivers are typically located at the interface of the display panel and the remainder of the electronic system.
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. The currently available flat panel display controllers and drivers such as those described immediately above have been designed to work almost exclusively with displays that need to be constantly refreshed. Because bi-stable displays (e.g., an array of interferometric modulators) do not require such constant refreshing, features that decrease power requirements may be realized through the use of bi-stable displays. However, if bi-stable displays are operated by the controllers and drivers that are used with current displays the advantages of a bi-stable display may not be optimized. Thus, improved controller and driver systems and methods for use with bi-stable displays are desired. For high speed bi-stable displays, such as the interferometric modulators described above, these improved controllers and drivers preferably implement low-refresh-rate modes, video rate refresh modes, and unique modes to facilitate the unique capabilities of bi-stable modulators. According to the methods and systems described herein, a bi-stable display may be configured to reduce power requirements in various manners.
In one embodiment illustrated by
Still referring to
In one embodiment, video data provided by data link 33 is not stored in the frame buffer 28, as is usually the case in many embodiments. It will also be understood that in some embodiments, a second driver controller (not shown) can also be used to render video data for the array driver 22. The data link 33 may comprise a SPI, I2C bus, or any other available interface. The array driver 22 can also include address decoding, row and column drivers for the display and the like. The network interface 27 can also provide video data directly to the array driver 22 at least partially in response to instructions embedded within the video data provided to the network interface 27. It will be understood by the skilled practitioner that arbiter logic can be used to control access by the network interface 27 and the processor 21 to prevent data collisions at the array driver 22. In one embodiment, a driver executing on the processor 21 controls the timing of data transfer from the network interface 27 to the array driver 22 by permitting the data transfer during time intervals that are typically unused by the processor 21, such as time intervals traditionally used for vertical blanking delays and/or horizontal blanking delays.
Advantageously, this design permits the server 2 to bypass the processor 21 and the driver controller 29, and to directly address a portion of the display array 30. For example, in the illustrated embodiment, this permits the server 2 to directly address a predefined display array area of the display array 30. In one embodiment, the amount of data communicated between the network interface 27 and the array driver 22 is relatively low and is communicated using a serial bus, such as an Inter-Integrated Circuit (I2C) bus or a Serial Peripheral Interface (SPI) bus. It will also be understood, however, that where other types of displays are utilized, that other circuits will typically also be used. The video data provided via data link 33 can advantageously be displayed without a frame buffer 28 and with little or no intervention from the processor 21.
As shown in
For a display array having the hysteresis characteristics of
In typical applications, a display frame may be created by asserting the set of column electrodes in accordance with the desired set of actuated pixels in the first row. A row pulse is then applied to the row 1 electrode, actuating the pixels corresponding to the asserted column lines. The asserted set of column electrodes is then changed to correspond to the desired set of actuated pixels in the second row. A pulse is then applied to the row 2 electrode, actuating the appropriate pixels in row 2 in accordance with the asserted column electrodes. The row 1 pixels are unaffected by the row 2 pulse, and remain in the state they were set to during the row 1 pulse. 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 video 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 array frames are also well known and may be used.
One embodiment of a client device 7 is illustrated in
The display 42 of exemplary client 40 may be any of a variety of displays, including a bi-stable display, as described herein with respect to, for example,
The components of one embodiment of exemplary client 40 are schematically illustrated in
The network interface 27 includes the antenna 43, and the transceiver 47 so that the exemplary client 40 can communicate with another device over a network 3, for example, the server 2 shown in
Processor 21 generally controls the overall operation of the exemplary client 40, although operational control may be shared with or given to the server 2 (not shown), as will be described in greater detail below. In one embodiment, the processor 21 includes a microcontroller, CPU, or logic unit to control operation of the exemplary client 40. Conditioning hardware 52 generally includes amplifiers and filters for transmitting signals to the speaker 44, and for receiving signals from the microphone 46. Conditioning hardware 52 may be discrete components within the exemplary client 40, or may be incorporated within the processor 21 or other components.
The input device 48 allows a user to control the operation of the exemplary client 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, a microphone is an input device for the exemplary client 40. When a microphone is used to input data to the device, voice commands may be provided by a user for controlling operations of the exemplary client 40.
In one embodiment, the driver controller 29, array driver 22, and display array 30 are appropriate 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, array driver 22 is a conventional driver or a bi-stable display driver (e.g., a interferometric modulator display). 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).
Power supply 50 is any of a variety of energy storage devices as are well known in the art. For example, in one embodiment, 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 one embodiment, the array driver 22 contains a register that may be set to a predefined value to indicate that the input video stream is in an interlaced format and should be displayed on the bi-stable display in an interlaced format, without converting the video stream to a progressive scanned format. In this way the bi-stable display does not require interlace-to-progressive scan conversion of interlace video data.
In some implementations control programmability resides, as described above, in a display controller which can be located in several places in the electronic display system. In some cases control programmability resides in the array driver 22 located at the interface between the electronic display system and the display component itself. 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.
In one embodiment, circuitry is embedded in the array driver 22 to take advantage of the fact that the output signal set of most graphics controllers includes a signal to delineate the horizontal active area of the display array 30 being addressed. This horizontal active area can be changed via register settings in the driver controller 29. These register settings can be changed by the processor 21. This signal is usually designated as display enable (DE). Most all display video interfaces in addition utilize a line pulse (LP) or a horizontal synchronization (HSYNC) signal, which indicates the end of a line of data. A circuit which counts LPs can determine the vertical position of the current row. When refresh signals are conditioned upon the DE from the processor 21 (signaling for a horizontal region), and upon the LP counter circuit (signaling for a vertical region) an area update function can be implemented.
In one embodiment, a driver controller 29 is integrated with the array driver 22. Such an embodiment is common in highly integrated systems such as cellular phones, watches, and other small area displays. Specialized circuitry within such an integrated array driver 22 first determines which pixels and hence rows require refresh, and only selects those rows that have pixels that have changed to update. With such circuitry, particular rows can be addressed in non-sequential order, on a changing basis depending on image content. This embodiment has the advantage that since only the changed video data needs to be sent through the interface, data rates can be reduced between the processor 21 and the display array 30. Lowering the effective data rate required between processor 21 and array driver 22 improves power consumption, noise immunity and electromagnetic interference issues for the system.
In the
The details of the structure of interferometric modulators that operate in accordance with the principles set forth above may vary widely. For example,
An embodiment of process flow is illustrated in
Again referring to
An embodiment of process flow is illustrated in
Starting at decision state 84, the client device 7 makes a determination whether an action at the client device 7 requires an application at the client device 7 to be started, or whether the server 2 has transmitted an application to the client device 7 for execution, or whether the server 2 has transmitted to the client device 7 a request to execute an application resident at the client device 7. If there is no need to launch an application the client device 7 remains at decision state 84. After starting an application, continuing to state 86, the client device 7 launches a process by which the client device 7 receives and displays video data. The video data may stream from the server 2, or may be downloaded to the client device 7 memory for later access. The video data can be video, or a still image, or textual or pictorial information. The video data can also have various compression encodings, and be interlaced or progressively scanned, and have various and varying refresh rates. The display array 30 may be segmented into regions of arbitrary shape and size, each region receiving video data with characteristics, such as refresh rate or compression encoding, specific only to that region. The regions may change video data characteristics and shape and size. The regions may be opened and closed and re-opened. Along with video data, the client device 7 can also receive control data. The control data can comprise commands from the server 2 to the client device 7 regarding, for example, video data characteristics such as compression encoding, refresh rate, and interlaced or progressively scanned video data. The control data may contain control instructions for segmentation of display array 30, as well as differing instructions for different regions of display array 30.
In one exemplary embodiment, the server 2 sends control and video data to a PDA via a wireless network 3 to produce a continuously updating clock in the upper right corner of the display array 30, a picture slideshow in the upper left corner of the display array 30, a periodically updating score of a ball game along a lower region of the display array 30, and a cloud shaped bubble reminder to buy bread continuously scrolling across the entire display array 30. The video data for the photo slideshow are downloaded and reside in the PDA memory, and they are in an interlaced format. The clock and the ball game video data stream text from the server 2. The reminder is text with a graphic and is in a progressively scanned format. It is appreciated that here presented is only an exemplary embodiment. Other embodiments are possible and are encompassed by state 86 and fall within the scope of this discussion.
Continuing to decision state 88, the client device 7 looks for a command from the server 2, such as a command to relocate a region of the display array 30, a command to change the refresh rate for a region of the display array 30, or a command to quit. Upon receiving a command from the server 2, the client device 7 proceeds to decision state 90, and determines whether or not the command received while at decision state 88 is a command to quit. If, while at decision state 90, the command received while at decision state 88 is determined to be a command to quit, the client device 7 continues to state 98, and stops execution of the application and resets. The client device 7 may also communicate status or other information to the server 2, and/or may receive such similar communications from the server 2. If, while at decision state 90, the command received from the server 2 while at decision state 88 is determined to not be a command to quit, the client device 7 proceeds back to state 86. If, while at decision state 88, a command from the server 2 is not received, the client device 7 advances to decision state 92, at which the client device 7 looks for a command from the user, such as a command to stop updating a region of the display array 30, or a command to quit. If, while at decision state 92, the client device 7 receives no command from the user, the client device 7 returns to decision state 88. If, while at decision state 92, a command from the user is received, the client device 7 proceeds to decision state 94, at which the client device 7 determines whether or not the command received in decision state 92 is a command to quit. If, while at decision state 94, the command from the user received while at decision state 92 is not a command to quit, the client device 7 proceeds from decision state 94 to state 96. At state 96 the client device 7 sends to the server 2 the user command received while at state 92, such as a command to stop updating a region of the display array 30, after which it returns to decision state 88. If, while at decision state 94, the command from the user received while at decision state 92 is determined to be a command to quit, the client device 7 continues to state 98, and stops execution of the application. The client device 7 may also communicate status or other information to the server 2, and/or may receive such similar communications from the server 2.
Starting at state 124 the server 2, in embodiment (1), waits for a data request via the network 3 from the client device 7, and alternatively, in embodiment (2) the server 2 sends video data without waiting for a data request from the client device 7. The two embodiments encompass scenarios in which either the server 2 or the client device 7 may initiate requests for video data to be sent from the server 2 to the client device 7.
The server 2 continues to decision state 128, at which a determination is made as to whether or not a response from the client device 7 has been received indicating that the client device 7 is ready (ready indication signal). If, while at state 128, a ready indication signal is not received, the server 2 remains at decision state 128 until a ready indication signal is received.
Once a ready indication signal is received, the server 2 proceeds to state 126, at which the server 2 sends control data to the client device 7. The control data may stream from the server 2, or may be downloaded to the client device 7 memory for later access. The control data may segment the display array 30 into regions of arbitrary shape and size, and may define video data characteristics, such as refresh rate or interlaced format for a particular region or all regions. The control data may cause the regions to be opened or closed or re-opened.
Continuing to state 130, the server 2 sends video data. The video data may stream from the server 2, or may be downloaded to the client device 7 memory for later access. The video data can include motion images, or still images, textual or pictorial images. The video data can also have various compression encodings, and be interlaced or progressively scanned, and have various and varying refresh rates. Each region may receive video data with characteristics, such as refresh rate or compression encoding, specific only to that region.
The server 2 proceeds to decision state 132, at which the server 2 looks for a command from the user, such as a command to stop updating a region of the display array 30, to increase the refresh rate, or a command to quit. If, while at decision state 132, the server 2 receives a command from the user, the server 2 advances to state 134. At state 134 the server 2 executes the command received from the user at state 132, and then proceeds to decision state 138. If, while at decision state 132, the server 2 receives no command from the user, the server 2 advances to decision state 138.
At state 138 the server 2 determines whether or not action by the client device 7 is needed, such as an action to receive and store video data to be displayed later, to increase the data transfer rate, or to expect the next set of video data to be in interlaced format. If, while at decision state 138, the server 2 determines that an action by the client is needed, the server 2 advances to state 140, at which the server 2 sends a command to the client device 7 to take the action, after which the server 2 then proceeds to state 130. If, while at decision state 138, the server 2 determines that an action by the client is not needed, the server 2 advances to decision state 142.
Continuing at decision state 142, the server 2 determines whether or not to end data transfer. If, while at decision state 142, the server 2 determines to not end data transfer, server 2 returns to state 130. If, while at decision state 142, the server 2 determines to end data transfer, server 2 proceeds to state 144, at which the server 2 ends data transfer, and sends a quit message to the client. The server 2 may also communicate status or other information to the client device 7, and/or may receive such similar communications from the client device 7.
In one embodiment, in view of the bi-stable nature of the display array 30, the image displayed by the display area 30 need not be refreshed in order to maintain the displayed image, and the frame buffer 28 may not be needed to store video data received via the first interface 202. In this embodiment, the video data is sent to the display by the driver controller 29 immediately after it is received and independently of any predetermined refresh period.
The driver controller 29 is in communication with the processor 21. The driver controller 29 can also be in communication with another device, such as the network interface 27. For example, the processor 21 and/or the network interface 27 can be configured to route packets of video data to either the first interface 202 or the second interface 204. The video data can correspond to raw graphical data and/or to graphical primitives for interpretation by the direct interface.
In one embodiment, video data that is received via the first interface 202 is targeted for presentation on a first region of the display array 30 and video data that is received via the second interface 204 is targeted for presentation on a second region of the display array 30. The regions may be defined during manufacture, or alternatively, dynamically by the driver controller 29, processor 21, or the server 2 (
In one embodiment, a dedicated bus is provided for the first interface 202 and the second interface 204. In this embodiment, the first interface 202 or the second interface 204 can be directly connected to either the processor 21 or the network interface 27 (
In some embodiments the arbiter 208 may or may not provide handshake functions, such as resolving access-contention for the array driver 22 between the first interface 202 and the second interface 204, maintaining data and/or address hold times and restricting data transfer rates as applicable. If necessary, the arbiter 208 communicates with the processor 21 via control link 207 for managing such handshake functions. In the illustrated embodiment, the arbiter 208 communicates with the display array 30 via array driver 22. In another embodiment the arbiter 208 may be integrated with array driver 22.
One embodiment further includes a circuit configured to schedule access to the display array 30. For example, if the display array 30 is partitioned, different portions of the display array 30 can have different refresh rates and different update techniques. For example, a first portion of the bi-stable display array 30 can be addressed line-at-a-time and a second portion of the display array 30 can be addressed in pixel-by-pixel manner.
Determining the states of pixels in the display area 30 can be a useful feature for rendering images to be displayed when the client device 7 may not have a frame buffer to store data for a graphical image that is then transferred to the display. The state of a pixel in the display array 30 is determined using the pulse sensing circuit 254. In one embodiment, the display array 30 comprises an interferometric modulator display. In another embodiment, the display array 30 comprises a thin film transistor (TFT) display. In addition, it should be noted that in at least one embodiment of an electrophoretic display, an active matrix substrate with TFTs is also used for control of the display.
In one embodiment, the display controller 29 determines a state of one or more pixels in the display array 30 in order to update the graphical image that is being displayed. One example of modifying content of the graphical image to update the image is to brighten or to dim a region. Brightening or dimming of a region can be achieved by, for example, selectively activating relatively more or relatively fewer pixels on the display array 30 in the region of interest.
As discussed earlier, in one embodiment, a stable state of the display array 30 is maintained by maintaining a bias on the display array 30. For example, a mirror disposed approximately adjacent to the intersection of a corresponding row line and a corresponding column line can be biased by the lines (conductors) within a selected voltage range to maintain the state of the mirror.
The short pulse generator 250 is configured to modulate at least one of a column line and/or a row line containing a modulating element of interest. A pulse of appropriate magnitude and relatively short duration can be applied to the selected row or column without disturbing or changing the state of the modulators connected to the selected row or column. The pulse sensing circuit 254 monitors a column or row line that is also connected to the modulating element of interest. The pulse sensing circuit detects an amplitude of a signal reflected from the modulating element of interest. Such an amplitude is dependent upon and can reveal the state of the modulating element of interest. The coupling between the applied and reflected pulses is highly dependent upon the state of the modulating element. High levels of coupling are associated with modulating elements in the collapsed state, where the two mirror components of the modulating element are in close proximity. Low levels of coupling are associated with modulating elements in the released state where the two mirror components of the modulating element are relatively distant from each other.
Where multiple mirrors in a sub-array are used to represent a pixel, the remaining mirrors can be similarly interrogated, and the retrieved states of the mirrors can be mapped to resolve the original state of the pixel. In one embodiment, multiple mirrors are modulated and monitored in parallel to speed the detection process. For example, a row line can carry a relatively short pulse, and multiple column lines can be monitored to simultaneously determine the states of corresponding mirrors coupled to the activated row line.
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.
This application claims priority to U.S. Provisional Application No. 60/613,617, titled “Method and Device For Bi-Stable Display,” filed Sep. 27, 2004, which is incorporated by reference, in its entirety. This application is related to U.S. application Ser. No. ______, attorney docket No. IRDM.107A titled “System Having Different Update Rates For Different Portions Of A Partitioned Display”, filed concurrently, U.S. application Ser. No. ______, attorney docket No. IRDM.108A titled “Method And System For Driving a Bi-stable Display”, filed concurrently, U.S. application Ser. No. ______, attorney docket No. IRDM.109A titled “System With Server Based Control Of Client Device Display Features”, filed concurrently, U.S. application Ser. No. ______, attorney docket No. IRDM.018A titled “Controller and Driver Features for Bi-Stable Display”, filed concurrently, and U.S. application Ser. No. ______, attorney docket No. IRDM.112A titled “System and Method of Transmitting Video Data”, filed concurrently, all of which are incorporated herein by reference and assigned to the assignee of the present invention.
Number | Date | Country | |
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60613617 | Sep 2004 | US |