Separating a compressed stream into multiple streams

Embodiments of the invention generally provide a display device that includes a controller that is communicatively coupled between a display source and source drivers. The controller and source drivers include respective decompression engines that can decompress the compressed data received from the display source. Instead of sending all of the compressed data to the source drivers, the controller evaluates the uncompressed data and identifies what portion of the compressed data corresponds to each of the source drivers. Moreover, the controller may determine a decompression engine state that corresponds to each portion of the compressed data. The saved engine state is transmitted to the source drivers which then initialize their decompression engines using the engine states.

FIELD OF THE INVENTION

This invention generally relates to updating a display, and more specifically, to transmitting compressed data to source drivers for updating the display.

BACKGROUND OF THE INVENTION

Display devices for updating images on a display screen are widely used in a variety of electronic systems. A typical display device includes a source that provides display data that is used to update the screen. The display data may be organized into display frames which are transmitted from the source to the display screen at a predefined rate. In one example, each display frame corresponds to an image to be displayed on the screen. The display screen may include display drivers that update the individual pixels on the display screen using the received display frames. The pixels in the display screen are typically assigned to one of the source drivers—e.g., the pixels in columns 1-5 are assigned to Source Driver 1, the pixels in columns 6-10 are assigned to Source Driver 2, and so forth.

BRIEF SUMMARY OF THE INVENTION

One embodiment described herein includes a method that decompresses compressed data to identify first data for a first source driver of the display device and second data for a second source driver of the display device where the compressed data including at least a portion of a display frame for a display device. The method also includes identifying a first decompression engine state corresponding to the first data and a second decompression engine state corresponding to the second data. The method includes transmitting a first stream comprising the first data and the first decompression engine state to the first source driver and transmitting a second stream comprising the second data and the second decompression engine state to the second source driver.

Another embodiment described herein includes a timing controller with a storage element configured to receive compressed data including at least one display frame for a display device and a decompression engine. The decompression engine is configured to decompress the received compressed data to identify first data for a first source driver of the display device and second data corresponding to a second source driver of the display device and identify a first decompression engine state corresponding to the first data and a second decompression engine state corresponding to the second data. The timing controller includes control logic configured to transmit a first stream comprising the first data and the first compression engine state to the first source driver and transmit a second stream comprising the second data and the second compression engine state to the second source driver.

Another embodiment described herein includes a display device with first and second source drivers for updating a display screen and one or more electrical connections. The display device also includes a timing controller coupled to the first and second source drivers via the one or more electrical connections. The timing controller includes a storage element configured to receive compressed data including at least one display frame for a display device and a decompression engine. The decompression engine is configured to decompress the received compressed data to identify first data for a first source driver of the display device and second data corresponding to a second source driver of the display device and identify a first decompression engine state corresponding to the first data and a second decompression engine state corresponding to the second data. The timing controller also includes control logic configured to transmit a first stream comprising the first data and the first compression engine state to the first source driver and transmit a second stream comprising the second data and the second compression engine state to the second source driver.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention provide display devices and methods that facilitate improved usability. In a display device, source drivers use received display frames to update the pixels in a display. For example, the display device may include a display source, such as a graphic processing unit, that compresses the display frames and transmits this compressed data to the source drivers which decompress the data and update the pixels. In one embodiment, the source drivers are assigned different portions of a display screen. For example, for a particular line update, the pixels in a first portion of the line are assigned to a first source driver, the pixels in the subsequent portion of the line are assigned to a second source driver, and so forth. As such, each source driver needs to receive only the compressed data that corresponds to the pixels assigned to it.

In one embodiment, the display device includes a controller (e.g., a timing controller or display controller) that is communicatively coupled between the display source and the source drivers. Like the source drivers, the controller also includes a decompression engine that can decompress the compressed data received from the display source. Instead of sending all of the compressed data to the source drivers, the controller evaluates the uncompressed data and identifies what portion of the compressed data corresponds to each of the source drivers. Using this information, the controller transmits only the relevant portion of the compressed data to each of the source drivers rather than transmitting all of the compressed data to each source driver.

In addition to identifying which portion of the compressed data should be transmitted to which source driver, the controller may determine a decompression engine state that corresponds to each portion of the compressed data. Stated differently, as the decompression engine on the controller decompresses the data, the controller saves the current state of the decompression engine when the controller identifies a portion of the compressed data that should be sent to a different source driver. For example, the decompression engine may currently be decompressing data that corresponds to Source Driver A, but once the engine begins decompressing data that corresponds to Source Driver B, the controller saves the current state of the decompression engine. This saved engine state (along with the portion of the compressed data corresponding Source Driver B) is transmitted to Source Driver B which then initializes its decompression engine using the engine state. As used herein, a “decompression engine state” includes all the necessary parameters and data to configure or initialize a decompression engine to a particular state. Accordingly, once initialized with the saved decompression engine state, the decompression engine on Source Driver B has the same configuration (i.e., state) as the decompression engine on the controller when the engine state was saved. Doing so enables the decompression engine on Source Driver B to begin decompressing its portion of the compressed data as if the decompression engine already decompressed the previous portion (or portions) of the compressed data. In this manner, by transmitting the engine states of the decompression engine on the controller to the source drivers, the display device is able to initialize the different decompression engines on the source drivers without requiring these engines to decompress all the compressed data, thereby reducing the power consumed by the source drivers as well as reducing the bandwidth needed to communicate with the source drivers (since only a portion of the compressed data, rather than all the compressed data, is sent to each source driver).

In another embodiment, the controller does not decompress the compressed data received from the display source. In one example, the compressed data is transmitted from the display source without first being received by the controller which then relays the compressed data to the source drivers. In this embodiment, all of the compressed data is sent to each of the source drivers. However, instead of each source driver decompressing all of the compressed data, one of the source drivers begins to decompress the compressed data until this source driver identifies display data that is intended for a different source driver. The source driver then transmits its current decompression engine state to a different source driver along with an address that indicates the location of the compressed data intended for that source driver. The source driver that receives the engine state can then initialize its decompression engine and begin decompressing the compressed data at the provided address. This process may then repeat until all the compressed data has been decompressed by the source drivers. While this embodiment enables the source drivers to decompress only a portion of the compressed data, the bandwidth used to transmit the compressed data to the source driver is increased since all of the compressed data is sent to each of the source drivers rather than only a portion of the compressed data being sent to each source driver.

FIG. 1is a block diagram of a display device100for transmitting compressed data to source drivers in accordance with an embodiment of the invention. The display device100may be configured to display information for an electronic system (not shown). As used in this document, the term “electronic system” (or “electronic device”) broadly refers to any system capable of electronically processing information. Some non-limiting examples of electronic systems include personal computers of all sizes and shapes, such as desktop computers, laptop computers, netbook computers, tablets, web browsers, e-book readers, and personal digital assistants (PDAs). Other examples include remote terminals, kiosks, and video game machines (e.g., video game consoles, portable gaming devices, and the like). Other examples include communication devices (including cellular phones, such as smart phones), and media devices (including recorders, editors, and players such as televisions, set-top boxes, music players, digital photo frames, and digital cameras). Additionally, the electronic system could be a host or a slave to the display device100.

The display device100includes a display source105, a controller110, a plurality of source drivers130, and a display135. The display source105may be a graphics processing unit, a separate or integrated electronic system, and the like. The display source105transmits compressed data to the controller110, which may reduce the bandwidth of the connection relative to sending uncompressed data. The compressed data may include at least a portion of a display frame which is used to by the source drivers (once the data is decompressed) to update the display135. In one embodiment, the display frames are compressed using a visually lossless algorithm such that a user cannot visually tell a difference between an image on the display135that was outputted using a compressed display frame or an uncompressed display frame. One such suitable compression algorithm is the Display Stream Compression (DSC) standard. However, the embodiments herein are not limited to visually lossless compression algorithms and may be used with any compression algorithm that compresses the display frame data.

The controller110may be a timing controller, display controller, and the like. The controller110may be part of an integrated circuit or system on a chip. Moreover, the controller110on the same substrate as the display source105(e.g., mounted on the same PCB) or mounted on different substrates. The controller110includes a decompression engine115A. In one embodiment, the decompression engine115A decompresses the compressed data received from the display source105and identifies what portion of the compressed data is assigned to the source drivers130. For example, the compressed data may include information for updating a line (e.g., a horizontal row) in the display135. However, the pixels in the first half of the line, which are in Portion A, are assigned to source driver130A, while the pixels in the second half of the line, which are in Portion B, are assigned to source driver130B. By decompressing the compressed data, the controller110determines whether the compressed data is intended for source driver130A or source driver130B (assuming only two source drivers in the display device100). Instead of relaying all of the compressed data to the source drivers130, the controller110relays the compressed data for the first half of the line to source driver130A and the compressed data for the second half of the line to source driver130B.

One advantage of transmitting compressed data rather than uncompressed data from the controller110and the source drivers130is that the bandwidth of the connections between the controller110and source drivers130is reduced. The bandwidth requirements are further reduced by sending only a portion of the compressed data to the source drivers130—i.e., only the display data necessary for updating the pixels assigned to the source drivers130. Many compression schemes, however, depend on information that was obtained when decompressing previous data in a data stream in order to decompress the current data in the data stream. That is, assuming a decompression engine receives a stream of compressed data, in order to decompress data in the middle of this stream, the decompression engine may need information that was obtained when decompressing the data at the beginning of the stream. Decompression schemes that use information obtained from decompressing previous portions of a compressed data stream to decompress later portions of the data stream are referred to herein as “dependent decompression.” If a dependent decompression scheme is used, when the controller110transmits only a portion of the compressed data to the source drivers130, decompression engines115on the source drivers130have not decompressed the previous portion of the compressed data, and thus, may lack the information necessary to decompress the received portion of the compressed data.

To handle this problem, when decompressing the compressed data, the decompression engine115A on the controller110saves its state upon identifying a portion of the compressed data that is intended for one of the source drivers130. For example, when the compression engine first identifies a portion of the compressed data intended for source driver130A, the engine115A saves its state (e.g., first engine state120) which includes the necessary information obtained from decompressing the previous portions of the compressed data (if any). The controller110transmits the first engine state120to the source driver130A which uses this state120to initialize decompression engine115B such that it is now in the same state as the first engine state120. Stated differently, the decompression engine115B is initialized to the same state as was decompression engine115A when the controller110identified a location in the compressed data that includes data for updating pixels assigned to source driver130A. Once decompression engine115B is initialized to the first engine state120, the source driver130A can decompress the received portion of the compressed data as if the decompression engine115B had already decompressed the previous portions of the compressed data (which it did not).

Similarly, once the controller110indentifies a portion of the compressed data intended for source driver130B (e.g., a second half of a line update), the controller110saves the current state of decompression engine115A (e.g., second engine state125) and transmits the second engine state125and the location of the portion of the compressed data that is intended for source driver130B. For example, the second engine state125will include any information obtained when decompressing the first half of the line update as well as any previous portions of the compressed data. Thus, when source driver130B initializes its decompression engine115C using the second engine state125, engine115C is in the same state as decompression engine115A when it finished decompressing the first half of the line update. The decompression engine115C can then correctly decompress the second half of the line update and source driver130B can update the pixels in Portion B according to the decompressed data.

In one embodiment, the controller110and each of the source drivers130are embodied in separate integrated circuits. Alternatively, the source drivers130may be included within a common integrated circuit. In one embodiment, the controller110and source drivers130may be mounted on a common substrate—e.g., a planar or flexible printed circuit board (PCB). The common substrate may also be attached to the display135. Alternatively, the source drivers130may be fixed to the display135to form a unitary system while the controller110is mounted on a separate substrate.

The display135may be any type of dynamic display capable of displaying a visual interface to a user, and may include any type of light emitting diode (LED), organic LED (OLED), cathode ray tube (CRT), liquid crystal display (LCD), plasma, electroluminescence (EL), or other display technology.

FIG. 2is a block diagram of a display device200for providing source drivers130with decompression engine states in accordance with an embodiment of the invention. Like inFIG. 1, display device200includes display source105, controller110, and source drivers130(the display has been omitted). However, in other embodiments, one or more of the elements in the display device200are part of another device (e.g., a host device) and are external to the display device200.

In addition to including decompression engine115A, controller110includes an input memory205, left address register210, and right address register215. The input memory205receives the compressed data from the display source105and forwards the compressed data to the decompression engine115A. Alternatively, the decompression engine may receive the compressed data directly from the display source105. Instead of relaying the compressed data to each of the source drivers130, as will be described in greater detail below, the controller110uses the decompression engine and the first and second (e.g., left and right) address registers210,215to identify only a portion of the compressed data to send to the source drivers130. For example, assuming the source drivers130A and130B are each assigned half of the pixels on the display, half of the compressed data is forwarded to source driver130A while the other half is forwarded to source driver130B. By first decompressing the data using engine115A, the controller110determines which half should be transmitted to which source driver130.

FIG. 3is a method300for providing source drivers with decompression engine states in accordance with an embodiment of the invention. Specifically, the method300describes a technique for operating the display device200shown inFIG. 2. AlthoughFIG. 2illustrates two source drivers130, the display device200may have any number of source drivers130which may be tasked with updating equal or unequal shares of the display. At block305, the controller receives compressed data from the display source which includes display data for updating a display frame on the device. For example, the compressed data may include a plurality of line updates that correspond to the number of display lines (or rows) in the display. The compressed data includes data for updating the pixels within the lines. As described above, the pixels within the lines may be assigned to different source drivers which use source lines (e.g., vertical electrodes) extending through the display to update the pixels.

At block310, the decompression engine on the controller decompresses the compressed data transmitted by the display source. As the data is decompressed, the controller evaluates the data to determine which source driver should receive the compressed data. For example, the controller may evaluate the location of the pixels in the decompressed data and determine which source driver is tasked with updating those pixels. Regardless how the controller evaluates the decompressed data, once a portion of the compressed data intended for a specific source driver is identified, the controller saves the starting address of the portion of the compressed data to a register. Referring back toFIG. 2, the display device includes two source drivers130and two registers210,215for storing addresses for portions of the compressed data corresponding to the source drivers130. For example, once the controller110determines the decompressed data is for a new line in the display, the controller110stores the starting location of the new line in the compressed data to the left address register210which corresponds to source driver130A. As the decompression engine115A continues to decompress data for the line, eventually control logic in the controller110identifies decompressed data for updating pixels on the second half of the line which are assigned to source driver130B. In response, the control logic stores the corresponding address of the compressed data containing display data for the second half of the line in the right address register215.

Referring back to the method300, in addition to identifying the addresses of the compressed data that correspond to the source drivers, the controller also saves the states of the decompression engine corresponding to the locations stored in the left and right address registers. Continuing the example above, once the controller determines the compressed data is for a new line in the display, the controller saves the current state of the engine as the first engine state. Once the controller determines the compressed data is for the second half of the line, the controller saves the current state of the decompression engine as the second engine state. These engine states contain all the necessary information for initializing a decompression engine on the source drivers to be in the same state the decompression engine on the controller was in when the engine begin decompressing data at the addresses saved in the left and right registers.

At block315, after identifying the right or left addresses and the corresponding engine states for the portions of the compressed data, the decompression engine on the controller discards the decompressed data. Stated differently, the decompressed data is deleted from the memory elements in the controller since the controller relays the compressed data, and not the decompressed data, to the source drivers.

At block320, the controller transmits to the source drivers only the portions of the compressed data intended for the individual source drivers. For example, the compressed data for the first half of a line update is sent to source driver130A while the compressed data for the second half of the line update is sent to source driver130B. To do so, the left and right addresses are used to index into the input memory to identify the portion of the compressed data that should be sent to the source drivers. Because the controller may determine the amount of compressed data for the first half of the line update (or the amount of data is constant), input memory uses the left address to identify a start location of the compressed data and transmits only the compressed data for the first half of the line update to the source driver130A. For example, if the amount of compressed data for a half of the line update is 50 bytes, the controller transmits, starting at the left address, the next 50 bytes of the compressed data. Similarly, once the controller identifies compressed data for the second half of the line update, the controller transmits this portion of the compressed data to source driver130B using the right address. As used herein, 50 bytes is used for illustratively purposes only and the data for half of the line update can be more or less than this amount.

By sending compressed data, the bandwidth of the connection between the controller and the source drivers is reduced. This bandwidth is further reduced since the controller decompresses the data to determine which portions of the compressed data should be sent to which source driver.

In one embodiment, the decompression engine on the controller operates faster than the decompression engines on the source drivers. For example, the decompression engine on the controller may operate two times, or three times faster than the decompression engines on the source drivers. As a result, the decompression engine on the controller is able to decompress and evaluate the data to identify the left and right addresses and the first and second engine states faster than the decompression engines on the source drivers can decompress the data. Assuming the decompression engine on the controller can operate at least twice as fast as the engines on the source drivers, once the controller identifies a new line in the compressed data, it can send the corresponding portion to source driver130A (e.g., the compressed data corresponding to the first half of the line update). While the decompression engine on source driver130A is decompressing its portion, the controller then identifies the second half of the line update and transmits this portion of the compressed data to source driver130B which begins to decompress the data. Because the controller is operating at twice the speed, source driver130A is still decompressing the first half of the line update when source driver130B receives the compressed data for the second half of the line update. Thus, the decompression engines on the source drivers can operate in parallel. Because the controller sends the engine states to the source drivers, the source drivers can simultaneously decompress different portions of the same line update.

In embodiments where the display device may include additional source drivers (e.g., six source drivers), the decompression engine on the controller can operate at, for example, five or six times faster than the decompression engines on the source drivers, and thus, the source drivers may be decompressing data associated with different portions of the same line update in parallel—e.g., the first source driver is decompressing the first one-sixth portion of the line update while the second source driver is decompressing the second one-sixth portion of the line update, while the third source driver is decompressing the third one-sixth portion of the line update, and so forth.

At block325, the source drivers initialize their decompression engines using the engine states received from the controller and begin to decompress the received portions of the compressed data. By so doing, the decompression engines of the source drivers have the necessary information and configuration to decompress the compress data and update the pixels assigned to the source drivers. Although the compressed data is decompressed twice—once by the decompression engine on the controller and once by the decompression engines on the source drivers—the advantage of doing so is the controller can send only the compressed data that is intended for the specific source driver rather than sending all the compressed data to each of the source drivers.

The method300then repeats as the decompression engine on the controller continues to decompress the compressed data. That is, the controller evaluates the decompressed data and identifies a different line update (e.g., a second line in the display) and updates the left address and saves the current engine state of the decompression engine. The portion of the compressed data corresponding to the first half of the second line update along with the saved engine state are transmitted to the source driver130A which begins decompressing the compressed data portion (assuming its finished decompressing the previously received portion).

FIG. 4is a block diagram of a display device400for providing source drivers with decompression engine states in accordance with an embodiment of the invention. Here, unlike display device200shown inFIG. 2, display device400includes a controller110where the compressed data is stored in buffers410that correspond to different source drivers130. That is, instead of the compressed data being store in a shared memory (e.g., input memory205), control logic in the decompression engine115A provides a control signal for a multiplexer405(or any other switching element) that routes a portion of the compressed data intended for the specific source driver130into the corresponding buffer410. Moreover, display device400includes three source drivers130that each updates a third of the pixels of the display, however, the display device400may include any number of source drivers130. For a given line update, source driver130A updates the first one-third of the pixels on the line, source driver130B updates the middle one-third of the pixels, and source driver130C updates the last one-third of the pixels. In one embodiment, the source drivers130may be tasked with updating a different number of pixels on the lines, and as such, the source drivers130may receive different portions of the display update data. For example, source driver130A and130B may each update two-fifths of the pixels in a line, while source driver130C updates the remaining one-fifth of the pixels. As a result, source driver130C may receive less compressed data (since it has to update half of the number pixels) as the other two source drivers130A and130B.

Like the display device200shown inFIG. 2, display device400uses the decompression engine115A to decompress the compressed data and identify the portions of the compressed data intended for the individual source drivers130and the engine states corresponding to those portions. AlthoughFIG. 4illustrates only one saved engine state per source driver130, the drivers130may store multiple different engine states that correspond to different portions of the compressed data.

FIG. 5is a method500for providing source drivers with decompression engine states in accordance with an embodiment of the invention. Specifically, the method500describes a technique for operating the display device400shown inFIG. 4. At block505, the controller receives compressed data from the display source which includes display data for updating a display frame on the device—e.g., a plurality of line updates that correspond to the number of display lines (or rows) in the display.

At block510, the decompression engine on the controller decompresses the compressed data transmitted by the display source. As the data is decompressed, the controller evaluates the data to determine which source driver should receive the compressed data. Once a portion of the compressed data intended for a specific source driver is identified, control logic in the controller uses the control signal to route the portion of the compressed data to the buffer corresponding to the source driver. Referring back toFIG. 4, the display device400includes three source drivers130and uses the three buffers—i.e., buffers410A,410B, and410C—for storing the portions of the compressed data for the source drivers130. For example, once the controller110determines the decompressed data is for a new line in the display, the controller110changes the control signal for the multiplexer405such that the compressed data currently being received is routed to buffer410A. As the decompression engine115A continues to decompress the data, eventually the controller110identifies decompressed data for updating pixels on the middle one-third of the line which are assigned to source driver130B. In response, the controller110updates the control signal such that the compressed data is routed to buffer410B. Once the decompression engine115A identifies the last one-third of the line, the engine changes the control signal so the multiplexer405routes the compressed data into buffer410C.

In addition to updating the control signal, the controller110also saves the current state of the decompression engine115A corresponding to the portions of the compressed data stored in the buffers410. For example, the first engine state120includes the configuration data needed to decompress the data portion stored in buffer410A, the second engine state125includes the configuration data needed to decompress the data portion stored in buffer410B, and the third engine state415includes the configuration data needed to decompress the data portion stored in buffer410C.

Returning to the method500, at block515, the buffers transmit the stored data portions to the source drivers. Because a third of the compressed data is stored in the buffers, the data connections between the controller and the individual source drivers uses a third of the bandwidth relative to the bandwidth of the data connection between the display source and the controller. In addition to transmitting the portions of the compressed data to the source drivers, the controller also transmits the saved engine states corresponding to these portions to the source drivers. The engine states may be saved in the buffers along with the compressed data or the controller may use a separate data connection to transmit the engine states to the source drivers.

As discussed above, in one embodiment, the decompression engine on the controller operates faster than the decompression engines on the source drivers. As a result, the decompression engine on the controller is able to decompress and evaluate the data to selectively store the compressed data in the buffers faster than the decompression engines on source drivers can decompress the data. Referring back toFIG. 4, assuming the data connection between the controller110and each source driver130has only a third of the bandwidth as the data connection between the display source105and controller110, the buffers410may be transmitting portions of the compressed data in parallel. For example, assuming the decompression engine115A can decompress the compressed data at the rate it is received, the controller110can store the compressed data in the buffers410that is three times faster than the data can be transmitted to, and decompressed by, the source drivers130. Therefore, source driver130A may be decompressing data for the first one-third of a display line at the same time source driver130B is decompressing data for the middle one-third of the display line.

At block520, the source drivers initialize their decompression engines using the engine states received from the controller and begin to decompress the received portions of the compressed data. By so doing, the decompression engines of the source drivers have the necessary information and configuration to decompress the compressed data and update the pixels assigned to the source drivers.

FIG. 6is a block diagram of a display device600for sharing decompression engine states among the source drivers630in accordance with an embodiment of the invention. Unlike the display devices illustrated inFIGS. 2 and 4, display device600does not include a controller110. In one embodiment, the display source105includes a direct connection to the source drivers630. Alternatively, the display device600may include a controller that receives the data from the display source105and relays the compressed data605to the source drivers630, but the controller does not decompress the data. That is, the controller forwards the compressed data605to the source drivers630without evaluating the data to determine which data portions are intended for which source driver630. In either case, in this embodiment each source driver630receives all of the compressed data605rather than receiving only a portion of the compressed data605as done in the embodiments above.

The source drivers630each include a decompression engine615and a copy of the compressed data605. Moreover, the source drivers630include data connections to a neighboring or adjacent source driver. As shown, source driver630A includes a data connection to source driver630B which has a data connection to source driver630C. Assuming there are no other source drivers in the display device600, source driver630C includes a data connection to source driver630A. However, if there are additional source drivers, source driver630C would include a data connection to the next source driver. The last source driver would then have a data connection back to source driver630A.

In one embodiment, source drivers630use the data connections to share engine states so that the decompression engines615on each of the source drivers630do not need to decompress all of the compressed data605. For example, source driver630A begins to decompress the compressed data605until the driver630A determines that the decompressed data is for updating pixels that are not assigned to it. As will be described in more detail inFIG. 7, the source driver630A saves its current engine state (i.e., first engine state635) and transmits that state635to source driver630B. Source driver630A may also provide a starting address of the compressed data that corresponds to the first engine state635. Source driver630B initializes its decompression engine615B using the first engine state635and begins decompressing the compressed data605at the address provided by source driver630A until the source driver630B indentifies display data for pixels assigned to source driver630C. This process can then repeat.

FIG. 7is a method700for sharing decompression engine states among the source drivers in accordance with an embodiment of the invention. Specifically, the method700describes a technique for operating the display device600shown inFIG. 6. At block705, each source driver begins to receive the compressed data from the display source which includes display data for updating a display frame on the device—e.g., a plurality of line updates that correspond to the number of display lines (or rows) in the display.

At block710, one of the source drivers (e.g., the source driver assigned to update pixels at the leftmost portion of the display line) decompresses the first portion of the compressed data. To determine which source driver should start decompressing the compressed data, each of the source drivers may begin to decompress the data but only the source driver that updates the leftmost portion of the display continues to decompress the compressed data. The other source drivers stop decompressing the data once they determine the data is for updating pixels that are not assigned to them.

Once the leftmost source driver identifies data intended for a different source driver, the source driver saves the current state of its decompression engine along with a corresponding address in the compressed data. Using one of the data connections illustrated inFIG. 6, the source driver transmits the saved engine state and the corresponding address to a second source driver.

At block715, the second source driver initializes its decompression engine using the received engine state. By so doing, its decompression engine is configured as if it decompressed the first portion of the compressed data even though it was idle during this time. The second source driver uses the address to identify the correct starting location of the second portion of the compressed data and begins to decompress the data. Upon identifying display data in the compressed data that is intended for a third source driver, the second source driver saves the current state of its decompression engine along with the corresponding address in the compressed data. The second source driver then transmits the saved engine state and the corresponding address to the third source driver.

At block720, the third source driver initializes its decompression engine using the received engine state and begins to decompress a third portion of the compressed data at the address received from the second source driver. If there are only three source drivers in the display devices, upon identifying display data in the compressed data that is for a new line (i.e., the data is intended for the first source driver), the third source driver saves the current state of its decompression engine along with the corresponding address in the compressed data and transmits this information to the first source driver where the method700can repeat until all the compressed data has been decompressed and used by the three source drivers to update the pixels in the display.

In the method700, the source drivers wait for the previous source driver to decompress the compressed data and provide the appropriate decompression engine state which means the data is processed sequentially. However, in the method300and500inFIGS. 3 and 5, because the decompression engine on the controller may operate much faster than the decompression engines on the source drivers, the source drivers can decompress their respective portions in parallel rather than sequentially, thereby saving time. Furthermore, the method700transmits all of the compressed data to each of the source drivers, while methods300and500transmit only the relevant portions of the compressed data to each of the source drivers. As such, the bandwidth needed to transmit the compressed data to the source drivers shown inFIG. 6is greater than the bandwidth needed to transmit the compressed data from the controller to the source drivers as shown inFIGS. 2 and 4.

The embodiments described above assume that the compressed data is organized by display lines where the first part of the compressed data includes information for updating the uppermost display line in the display from the left to the right. That is, the compressed data for a particular line update is ordered such that the first part of the data is for the leftmost pixel in the line while the last part of the data is for the rightmost pixel in the line. However, this particular ordering of the compressed data is for illustrative purposes only and is not intended to limit the scope of this disclosure. Indeed, the embodiments herein may be used when the data is ordered based on columns rather than lines or when the compressed data starts with the rightmost pixel in a line rather than the leftmost pixel. One of ordinary skill will readily recognize that the embodiments herein can be adapted for any particular ordering of the compressed display data.

The embodiments and examples set forth herein were presented in order to best explain the present invention and its particular application and to thereby enable those skilled in the art to make and use the invention. However, those skilled in the art will recognize that the foregoing description and examples have been presented for the purposes of illustration and example only. The description as set forth is not intended to be exhaustive or to limit the invention to the precise form disclosed.