Patent Application
20160189666
This invention generally relates to updating a display, and more specifically, to transmitting compressed data to source drivers for updating the display.
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.
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.
The preferred exemplary embodiment of the present invention will hereinafter be described in conjunction with the appended drawings, where like designations denote like elements, and:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
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.
The display device 100 can be implemented as a physical part of the electronic system, or can be physically separate from the electronic system. As appropriate, the display device 100 may communicate with parts of the electronic system using any one or more of the following: buses, networks, and other wired or wireless interconnections. Examples include I2C, SPI, PS/2, Universal Serial Bus (USB), Bluetooth, RF, and IRDA.
The display device 100 includes a display source 105, a controller 110, a plurality of source drivers 130, and a display 135. The display source 105 may be a graphics processing unit, a separate or integrated electronic system, and the like. The display source 105 transmits compressed data to the controller 110, 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 display 135. 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 display 135 that 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 controller 110 may be a timing controller, display controller, and the like. The controller 110 may be part of an integrated circuit or system on a chip. Moreover, the controller 110 on the same substrate as the display source 105 (e.g., mounted on the same PCB) or mounted on different substrates. The controller 110 includes a decompression engine 115A. In one embodiment, the decompression engine 115A decompresses the compressed data received from the display source 105 and identifies what portion of the compressed data is assigned to the source drivers 130. For example, the compressed data may include information for updating a line (e.g., a horizontal row) in the display 135. However, the pixels in the first half of the line, which are in Portion A, are assigned to source driver 130A, while the pixels in the second half of the line, which are in Portion B, are assigned to source driver 130B. By decompressing the compressed data, the controller 110 determines whether the compressed data is intended for source driver 130A or source driver 130B (assuming only two source drivers in the display device 100). Instead of relaying all of the compressed data to the source drivers 130, the controller 110 relays the compressed data for the first half of the line to source driver 130A and the compressed data for the second half of the line to source driver 130B.
One advantage of transmitting compressed data rather than uncompressed data from the controller 110 and the source drivers 130 is that the bandwidth of the connections between the controller 110 and source drivers 130 is reduced. The bandwidth requirements are further reduced by sending only a portion of the compressed data to the source drivers 130—i.e., only the display data necessary for updating the pixels assigned to the source drivers 130. 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 controller 110 transmits only a portion of the compressed data to the source drivers 130, decompression engines 115 on the source drivers 130 have 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 engine 115A on the controller 110 saves its state upon identifying a portion of the compressed data that is intended for one of the source drivers 130. For example, when the compression engine first identifies a portion of the compressed data intended for source driver 130A, the engine 115A saves its state (e.g., first engine state 120) which includes the necessary information obtained from decompressing the previous portions of the compressed data (if any). The controller 110 transmits the first engine state 120 to the source driver 130A which uses this state 120 to initialize decompression engine 115B such that it is now in the same state as the first engine state 120. Stated differently, the decompression engine 115B is initialized to the same state as was decompression engine 115A when the controller 110 identified a location in the compressed data that includes data for updating pixels assigned to source driver 130A. Once decompression engine 115B is initialized to the first engine state 120, the source driver 130A can decompress the received portion of the compressed data as if the decompression engine 115B had already decompressed the previous portions of the compressed data (which it did not).
Similarly, once the controller 110 indentifies a portion of the compressed data intended for source driver 130B (e.g., a second half of a line update), the controller 110 saves the current state of decompression engine 115A (e.g., second engine state 125) and transmits the second engine state 125 and the location of the portion of the compressed data that is intended for source driver 130B. For example, the second engine state 125 will 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 driver 130B initializes its decompression engine 1150 using the second engine state 125, engine 1150 is in the same state as decompression engine 115A when it finished decompressing the first half of the line update. The decompression engine 1150 can then correctly decompress the second half of the line update and source driver 130B can update the pixels in Portion B according to the decompressed data.
In one embodiment, the controller 110 and each of the source drivers 130 are embodied in separate integrated circuits. Alternatively, the source drivers 130 may be included within a common integrated circuit. In one embodiment, the controller 110 and source drivers 130 may 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 display 135. Alternatively, the source drivers 130 may be fixed to the display 135 to form a unitary system while the controller 110 is mounted on a separate substrate,
The display 135 may 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.
In addition to including decompression engine 115A, controller 110 includes an input memory 205, left address register 210, and right address register 215. The input memory 205 receives the compressed data from the display source 105 and forwards the compressed data to the decompression engine 115A. Alternatively, the decompression engine may receive the compressed data directly from the display source 105. Instead of relaying the compressed data to each of the source drivers 130, as will be described in greater detail below, the controller 110 uses the decompression engine and the first and second (e.g., left and right) address registers 210, 215 to identify only a portion of the compressed data to send to the source drivers 130. For example, assuming the source drivers 130A and 130B are each assigned half of the pixels on the display, half of the compressed data is forwarded to source driver 130A while the other half is forwarded to source driver 130B. By first decompressing the data using engine 115A, the controller 110 determines which half should be transmitted to which source driver 130.
At block 310, 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 updated 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 to
Referring back to the method 300, 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 ail 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 block 315, 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 block 320, 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 driver 130A while the compressed data for the second half of the line update is sent to source driver 130B. 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 driver 130A. 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 driver 130B 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 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 driver 130A (e.g., the compressed data corresponding to the first half of the line update). While the decompression engine on source driver 130A 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 driver 1303 which begins to decompress the data. Because the controller is operating at twice the speed, source driver 130A is still decompressing the first half of the line update when source driver 130B 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 block 325, 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 method 300 then 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 driver 130A which begins decompressing the compressed data portion (assuming its finished decompressing the previously received portion).
Like the display device 200 shown in
At block 510, 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 to
In addition to updating the control signal, the controller 110 also saves the current state of the decompression engine 115A corresponding to the portions of the compressed data stored in the buffers 410. For example, the first engine state 120 includes the configuration data needed to decompress the data portion stored in buffer 410A, the second engine state 125 includes the configuration data needed to decompress the data portion stored in buffer 410B, and the third engine state 415 includes the configuration data needed to decompress the data portion stored in buffer 410C.
Returning to the method 500, at block 515, 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 to
At block 520, 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.
The source drivers 630 each include a decompression engine 615 and a copy of the compressed data 605. Moreover, the source drivers 630 include data connections to a neighboring or adjacent source driver. As shown, source driver 630A includes a data connection to source driver 630B which has a data connection to source driver 630C. Assuming there are no other source drivers in the display device 600, source driver 630C includes a data connection to source driver 630A. However, if there are additional source drivers, source driver 6300 would include a data connection to the next source driver. The last source driver would then have a data connection back to source driver 630A.
In one embodiment, source drivers 630 use the data connections to share engine states so that the decompression engines 615 on each of the source drivers 630 do not need to decompress all of the compressed data 605. For example, source driver 630A begins to decompress the compressed data 605 until the driver 630A determines that the decompressed data is for updating pixels that are not assigned to it. As will be described in more detail in
At block 710, 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 in
At block 715, 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 block 720, 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 method 700 can 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 method 700, 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 method 300 and 500 in
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.
It should be understood that while many embodiments of the invention are described in the context of a fully functioning apparatus, the mechanisms of the present invention are capable of being distributed as a program product (e.g., software) in a variety of forms. For example, the mechanisms of the present invention may be implemented and distributed as a software program on information bearing media that are readable by electronic processors (e.g., non- transitory computer-readable and/or recordable/writable information bearing media readable by the display device). Additionally, the embodiments of the present invention apply equally regardless of the particular type of medium used to carry out the distribution. Examples of non-transitory, electronically readable media include various discs, memory sticks, memory cards, memory modules, and the like. Electronically readable media may be based on flash, optical, magnetic, holographic, or any other storage technology.
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.
