Data transmission method, display driving circuit thereof and host device

Abstract

The invention discloses a data transmission method, which is used for a display driving circuit, and comprises the following steps: receiving at least one first synchronization signal, and the at least one first synchronization signal is used for determining a frame period for a plurality of image data on an image frame; for first image data to be refreshed in the plurality of image data, receiving the first image data in a first transmission period corresponding to the first image data; and for second image data which is not refreshed in the plurality of pieces of image data, stopping receiving the second image data in a second transmission period corresponding to the second image data.

Description

Technical Field

[0001] The present invention relates to a data transmission method for a display driving circuit and a host device, and in particular to a data transmission method capable of realizing partial refresh of display data between the display driving circuit and the host device. Background Art

[0002] In recent years, display data has mostly been transmitted using the Mobile Industry Processor Interface (MIPI). Current MIPI specifications include video mode and command mode. In command mode, the display typically has a frame buffer. Display data transmitted via the MIPI is written to the frame buffer. When the display refreshes, the corresponding display data is retrieved from the frame buffer. In video mode, the display does not require a frame buffer. Instead, when the display is refreshed, the host sends display data via the MIPI to directly refresh the display. Summary of the Invention

[0003] Therefore, the main purpose of the present invention is to provide a data transmission method that can realize partial refresh of display data between a display driving circuit and a host device.

[0004] An embodiment of the present invention discloses a data transmission method, which is used in a display driving circuit and includes the following steps: receiving at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for multiple image data on an image frame; for a first image data to be refreshed among the multiple image data, receiving the first image data within a first transmission period corresponding to the first image data; and for a second image data not to be refreshed among the multiple image data, stopping receiving the second image data within a second transmission period corresponding to the second image data.

[0005] Another embodiment of the present invention discloses a display driving circuit, which is used to receive at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for multiple image data on an image frame; for a first image data to be refreshed among the multiple image data, the first image data is received during a first transmission period corresponding to the first image data; and for a second image data not to be refreshed among the multiple image data, the second image data is stopped from being received during a second transmission period corresponding to the second image data.

[0006] Another embodiment of the present invention discloses a data transmission method, which is used for a host device and includes the following steps: outputting at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for multiple image data on a first image frame; for a first image data to be refreshed among the multiple image data, transmitting the first image data within a first transmission period corresponding to the first image data; and for a second image data not to be refreshed among the multiple image data, stopping transmitting the second image data within a second transmission period corresponding to the second image data. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 FIG. 1 is a schematic diagram of a display system according to an embodiment of the present invention.

[0008] Figure 2 A schematic diagram illustrating a display screen in a display system refreshing an image in a general manner.

[0009] Figure 3 This is a timing diagram of a transmission interface in which a host device transmits image data to a display driver circuit for display screen refresh under normal video mode.

[0010] Figure 4 This is a timing diagram of a transmission interface in which a host device transmits part of image data to a display driving circuit for display screen refresh according to an embodiment of the present invention.

[0011] Figure 5 Schematic diagram of partially refreshing an image on a display screen in a display system according to an embodiment of the present invention.

[0012] Figure 6 This is a data transmission method and a refresh method in a display system when the image frame does not change according to an embodiment of the present invention.

[0013] Figure 7 Based on Figure 6 A timing diagram of signals and data transmitted between a host device and a display driving circuit under a data transmission mode.

[0014] Figure 8 Another embodiment of the present invention shows a data transmission method and a refresh method in a system.

[0015] Figure 9 Based on Figure 8 A timing diagram of signals and data transmitted between a host device and a display driving circuit under a data transmission mode.

[0016] Figure 10 Another embodiment of the present invention shows a data transmission method and a refresh method in a system.

[0017] Figure 11 Based on Figure 10 A timing diagram of signals and data transmitted between a host device and a display driving circuit under a data transmission mode.

[0018] Figure 12 Another embodiment of the present invention shows a data transmission method and a refresh method in a system.

[0019] Figure 13 Based on Figure 12 A timing diagram of signals and data transmitted between a host device and a display driving circuit under a data transmission mode.

[0020] Figure 14 A data transmission method in which X-direction partition refresh is added to the embodiment of the present invention.

[0021] Figure 15 Another data transmission method for adding X-direction partition refresh is provided in the embodiment of the present invention.

[0022] Figure 16 Schematic diagram of a data transmission process according to an embodiment of the present invention.

[0023] Figure 17 Schematic diagram of another data transmission process according to an embodiment of the present invention.

[0024] The description of the accompanying drawings is as follows:

[0025] 10 Display System

[0026] 100 host devices

[0027] 102 Display Driver Circuit

[0028] 104 Display

[0029] 110 Memory

[0030] 112_1, 112_2 switches

[0031] 114 Image Processing Circuit

[0032] Z1-Z3 areas

[0033] N, N+1, N+2 image frames

[0034] VSYNC vertical synchronization signal

[0035] HSYNC horizontal synchronization signal

[0036] EXT_HSYNC external horizontal synchronization signal

[0037] VFP, VFP_0~VFP_M vertical front porch

[0038] VBP, VBP_0~VBP_M vertical back corridor

[0039] L0~L127 data lines

[0040] HBP Level Back Porch

[0041] HFP Level Front Porch

[0042] 160, 170 Data transmission process

[0043] Steps 1602-1606, 1702-1706 DETAILED DESCRIPTION

[0044] Figure 1 FIG1 is a schematic diagram of a display system 10 according to an embodiment of the present invention. The display system 10 includes a host device 100, a display driver circuit 102, and a display screen 104. The host device 100 can function as a video source or video providing unit, outputting image data to the display driver circuit 102 for display on the display screen 104. The display driver circuit 102 processes the image data and converts the image data into corresponding data voltages for output to pixels on the display screen 104. Correspondingly, the display driver circuit 102 can also output control signals to the display screen 104 to control the sequential activation of each pixel to receive the data voltage. In one embodiment, the host device 100 can be, for example, an application processor (AP), a central processing unit (CPU), a microprocessor (MCU), a microcontroller unit (MCU), or any other type of system processing device. In one embodiment, the display driver circuit 102 can be implemented in an integrated circuit (IC) to form a display driver integrated circuit (DDIC). In one embodiment, the display screen 104 may be any type of display device, such as a light-emitting diode (LED) panel, an organic light-emitting diode (OLED) panel, a liquid crystal display (LCD) panel, etc., but is not limited thereto.

[0045] The display driver circuit 102 includes a memory 110, switches 112_1 and 112_2, and an image processing circuit 114. The memory 110 may be, for example, a static random access memory (SRAM) or a graphics random access memory (GRAM), which may function as a frame buffer to store display data from the host device 100. The image processing circuit 114 may be used to perform various image processing on the display data to enhance visual effects. Such image processing may include, but is not limited to, subpixel rendering and demura correction. Furthermore, the host device 100 may transmit display data to the display driver circuit 102 via a mobile industry processor interface (MIPI). As described above, the specifications of the MIPI include video mode and command mode. Therefore, the display driver circuit 102 can control the switches 112_1 and 112_2 according to the operating mode of the mobile industry processor interface. In different operating modes, the display data from the host device 100 can be directly output to the display screen 104 (e.g., in the video mode), or the display data can be written into the memory 110 for storage and then output from the memory 110 to the display screen 104 (e.g., in the command mode).

[0046] Figure 2 Figure 1 is a diagram illustrating a typical method for refreshing an image on the display screen 104 in the display system 10. Specifically, the active area of ​​the display screen 104 is divided into three zones, Z1 through Z3. The letter "A" is displayed in the current image frame N. In the next image frame N+1, only the image content in zone Z2 changes, while the images in zones Z1 and Z3 remain unchanged.

[0047] Figure 3 This is a timing diagram of the transmission interface in which the host device 100 transmits image data to the display driver circuit 102 for the display screen 104 to refresh the image under normal video mode. Figure 3 1 shows various data / signals transmitted on the transmission interface between the host device 100 and the display driving circuit 102, including a vertical synchronization signal VSYNC, a horizontal synchronization signal HSYNC, and display data. Figure 3Also shown is an external horizontal synchronization signal EXT_HSYNC received by the display driving circuit 102 , as well as the status of the display screen 104 and the transmission channel status of the transmission interface (such as MIPI).

[0048] The display driver circuit 102 can use the vertical synchronization signal VSYNC, the horizontal synchronization signal HSYNC, and the external horizontal synchronization signal EXT_HSYNC to determine the timing of the display driver circuit 102 processing display data. The vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC can be provided to the display driver circuit 102 by the host device 100, while the external horizontal synchronization signal EXT_HSYNC can be received by the display driver circuit 102 from an external device. Specifically, the vertical synchronization signal VSYNC is used to determine the frame period for a frame of image (e.g., image frame N, N+1, etc.). The horizontal synchronization signal HSYNC and the external horizontal synchronization signal EXT_HSYNC are used to determine the display time of a row of image data. The display driver circuit 102 can select to receive at least one of the horizontal synchronization signal HSYNC and the external horizontal synchronization signal EXT_HSYNC to perform timing synchronization control for each row.

[0049] like Figure 3 As shown, a frame period determined by the vertical synchronization signal VSYNC may include a data transmission period, a vertical front porch (VFP) VFP_0-VFP_M, and a vertical back porch (VBP) VBP_0-VBP_M. The vertical back porch VBP_0-VBP_M is the time interval between the pulse of the vertical synchronization signal VSYNC and the start of transmission of valid image data. The vertical front porch VFP_0-VFP_M is the time interval between the end of valid image data transmission and the next pulse of the vertical synchronization signal VSYNC. The data transmission period is used to transmit valid image data. Assuming that the display screen 104 includes 128 rows of pixels, based on the horizontal synchronization signal HSYNC (or external horizontal synchronization signal EXT_HSYNC), the data transmission period may include 128 line times, which are used to transmit the image data lines L0-L127 (hereinafter referred to as data lines) required for each row of pixels. Furthermore, each row time includes not only the time interval for transmitting each data row L0 to L127, but also a horizontal front porch (HFP) and a horizontal back porch (HBP) (omitted for simplicity). Figure 3 middle).

[0050] Please refer to Figure 3 Matching Figure 2As described above, in normal video mode, the host device 100 needs to transmit image data for the entire screen. Therefore, during the data transmission period, the host device 100 needs to transmit all data rows L0-L127 of an image frame (e.g., N+1) to the display driver circuit 102. Accordingly, the display driver circuit 102 can control the display screen 104 to refresh the entire screen, that is, to refresh areas Z1-Z3, regardless of whether the image content has changed.

[0051] In this scenario, the mobile processor interface must transmit all image data during the entire data transmission period, resulting in significant power consumption. Furthermore, regardless of whether the image content changes, the display screen 104 is refreshed. In other words, the display driver circuit 102 transmits image data and its corresponding control signals to all display areas on the display screen 104. This results in a significant amount of potential switching on the data lines and scan lines on the display screen 104, requiring frequent charging and discharging, which in turn generates significant power consumption.

[0052] To save power, the host device 100 can transmit only the image data that needs to be updated to the display driver circuit 102. The display driver circuit 102 then updates only the portion of the display screen 104 that needs to be updated based on the received image data and the corresponding image position information. In one embodiment, the host device 100 notifies the display driver circuit 102 of the range of image data that needs to be updated during the Nth frame. During the (N+1)th frame, the host device 100 transmits only the image data that needs to be updated, and the display driver circuit 102 updates only this portion of the image data.

[0053] Figure 4 This is a timing diagram of the transmission interface in which the host device 100 transmits part of the image data to the display driver circuit 102 for the display screen 104 to refresh the image. Figure 3 Similar to the example of , the host device 100 can transmit at least one synchronization signal to the display driver circuit 102, which includes a vertical synchronization signal VSYNC and a horizontal synchronization signal HSYNC. The display driver circuit 102 can also receive an external horizontal synchronization signal EXT_HSYNC from an external device. The functions and operation methods of the above synchronization signals are the same as Figure 3 , I will not go into details here.

[0054] Similarly, assuming that an image frame on the display screen 104 includes 128 rows of pixels (i.e., 128 data rows (L0-L127)), in this example, only rows 51 to 70 are to be refreshed. In this case, the host device 100 only transmits the corresponding data rows L50-L69 to the display driver circuit 102. Correspondingly, the display driver circuit 102 controls the display screen 104 to refresh only the pixel rows corresponding to the data rows L50-L69, and does not refresh the other pixel rows. Please refer to Figure 5 Matching Figure 4 As shown, the display screen 104 is refreshed only in the area Z2, and the images in the areas Z1 and Z3 are not changed, so they are not refreshed.

[0055] For example, during the Nth frame, the host device 100 may write information or instructions about the image update range into a specific register of the display driver circuit 102. This specific register stores information about starting and stopping data line updates. Next, during the (N+1)th frame, the host device 100 will continue to transmit image data to the display driver circuit 102 according to the original timing, but only during the timing corresponding to data lines L50-L69. During the timing of the remaining data lines, the host device 100 will only transmit the horizontal synchronization signal HSYNC to the display driver circuit 102 or enter a low-power mode. Simultaneously, the display driver circuit 102 will only refresh the image data on the data lines (or source lines) for data lines L50-L69, while the remaining data lines will maintain the data from the Nth frame. If the display screen 104 is an organic light-emitting diode panel, the data lines whose image data is not updated can be fixed at a specific voltage.

[0056] More specifically, if Figure 4 As shown, data lines L0-L127 within an image frame each include corresponding transmission periods, based on the timing determined by the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC (or the external horizontal synchronization signal EXT_HSYNC). Each data line L0-L127 corresponds to a transmission period determined by a pulse of the horizontal synchronization signal HSYNC. In other words, based on the control of the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC (and / or the external horizontal synchronization signal EXT_HSYNC), the timing of the mobile processor interface can reserve transmission time for each data line L0-L127. Among the data rows L0-L127, for the data rows L50-L69 to be refreshed, the host device 100 may transmit the data rows L50-L69 to the display driver circuit 102 during their corresponding transmission periods. For the other data rows L0-L49 and L70-L127 not to be refreshed, the host device 100 may stop transmitting image data during their corresponding transmission periods, and the display driver circuit 102 correspondingly stops receiving image data.

[0057] like Figure 5As shown, the display driver circuit 102 can operate in the video mode of the mobile processor interface. Switch 112_1 is turned on and switch 112_2 is turned off, allowing data lines L50-L69 from the host device 100 to bypass memory 110 and be directly transmitted to the image processing circuit 114. After processing by the image processing circuit 114, corresponding data voltages are generated. The display driver circuit 102 then outputs these data voltages to the display screen 104 and simultaneously outputs corresponding control signals to the display screen 104 to turn on the pixels in the areas to be refreshed on the display screen 104, allowing them to receive the corresponding data voltages. Meanwhile, for the remaining data lines L0-L49 and L70-L127 that have not been refreshed, the display driver circuit 102 can stop outputting any data voltages to the display screen 104 to reduce power consumption generated by the charging and discharging of the data lines on the display screen 104. At this time, the display driver circuit 102 can also stop outputting control signals to the display screen 104 or maintain the control signals at a specific level to keep the corresponding pixels off.

[0058] In one embodiment, during the period when the host device 100 stops transmitting image data to the display driver circuit 102, the mobile processor interface can be set to a power-saving state. The power-saving state can be achieved in a variety of ways. In one power-saving state, the mobile processor interface does not output image data during the data transmission period corresponding to the unrefreshed data rows, thereby stopping data transmission. In this case, the host device 100 only transmits packets of the vertical synchronization signal VSYNC and the horizontal synchronization signal HSYNC to the display driver circuit 102 via the mobile processor interface. Correspondingly, the display driver circuit 102 can determine the timing of data transmission based on the horizontal synchronization signal HSYNC packet (such as the horizontal synchronization start (HSS) signal in the packet).

[0059] In another power saving state, in order to further reduce power consumption, the host device 100 can stop outputting the horizontal synchronization signal HSYNC to the display driver circuit 102 during the period when the host device 100 stops transmitting image data to the display driver circuit 102. At this time, the transmission channel of the mobile industry processor interface does not switch levels to stop signal / data transmission. For example, Figure 4As shown, during the transmission period originally reserved for data lines L0-L49 and L70-L127, since both image data and the horizontal synchronization signal HSYNC cease transmission, the transmission channel in the mobile industry processor interface can be set to LP-11, a channel state in the mobile industry processor interface's low-power mode. In this case, the differential channels in the transmission channel are locked at a high level and do not switch, which reduces the power consumption of the mobile industry processor interface. It should be noted that since the host device 100 stops outputting the horizontal synchronization signal HSYNC, the display driver circuit 102 must receive an external horizontal synchronization signal EXT_HSYNC from an external device (via an interface other than the mobile industry processor interface) and use the external horizontal synchronization signal EXT_HSYNC to control the timing of each line of image data, that is, to determine the transmission period of each line of image data.

[0060] In one embodiment, the host device 100 may output a command to the display driver circuit 102 before transmitting a portion of the display data of an image frame to indicate the range of the image data to be refreshed and the image data not to be refreshed (e.g., the coordinates of the area or block to be refreshed). Figure 4 As shown, for the display data of image frame N+1, the host device 100 can transmit instructions in the vertical front corridor (e.g., VFP_0) before the pulse corresponding to image frame N+1 in the vertical synchronization signal VSYNC. Alternatively, the host device 100 can transmit instructions in the vertical back corridor before the data transmission period, or provide information about the image data range to be refreshed to the display driver circuit 102 at some other earlier time point in advance. Alternatively, the host device 100 can transmit instructions related to the image data range to be refreshed to the display driver circuit 102 via other transmission interfaces.

[0061] When the display driver circuit 102 receives a command from the host device 100, it determines the image data range to be refreshed and the image data range not to be refreshed according to the command, and controls the display screen 104 to refresh accordingly. Based on the timing information provided by the horizontal synchronization signal HSYNC (and / or the external horizontal synchronization signal EXT_HSYNC), the display driver circuit 102 can know the transmission period corresponding to each line of image data and receive image data during the transmission period corresponding to the range to be refreshed.

[0062] It is worth noting that the host device 100 transmitting the instruction regarding the range of image data to be refreshed is selective. In another embodiment, the host device 100 does not notify the display driver circuit 102 of the range of image data that needs to be updated / refreshed. In the data rows that do not require image update, the host device 100 only transmits the horizontal synchronization signal HSYNC or directly enters a low power mode (such as LP-11). At this time, the display driver circuit 102 does not provide the range of image data to be refreshed through the host device 100, but determines the range of image data to be refreshed and image data not to be refreshed based on the signal / data transmission status on the transmission interface. During the transmission period corresponding to each row of image data, the display driver circuit 102 can determine whether there is a high-speed switching signal on the data transmission channel of the mobile industry processor interface, or whether it is in a power saving state, and determine the range of image data to be refreshed accordingly. For example, based on the horizontal synchronization signal HSYNC packet (and / or the timing information provided by the external horizontal synchronization signal EXT_HSYNC), the display driver circuit 102 can count the number of received HSYNC / EXT_HSYNC pulses. Furthermore, the display driver circuit 102 knows the length of the vertical back corridor, which includes the number of HSYNC / EXT_HSYNC pulses. This pulse count can be used to determine the start time of a data transmission period and the corresponding transmission time of each subsequent row of image data. Therefore, if no high-speed signal is received on the data transmission channel after the data transmission period begins, the display driver circuit 102 can determine that the corresponding image data has not been refreshed. If image data is subsequently received within a certain transmission period, it can be determined that the image data has begun to be refreshed at this position.

[0063] In this way, the display driver circuit 102 refreshes the image data of the data lines (or source lines) only on the data lines that need to be updated, while the other data lines maintain the data of the previous frame. If the display screen 104 is an organic light emitting diode panel, the data lines without updated image data can be fixed at a specific voltage.

[0064] Also, please note that in Figure 5In the embodiment, switch 112_1 is turned on and switch 112_2 is turned off, allowing data rows L50-L69 to bypass memory 110 and be directly processed by image processing circuit 114 and immediately output to display screen 104 for display. In another embodiment, switch 112_2 can be turned on and switch 112_1 turned off, allowing image data from host device 100 to be transferred to memory 110 for storage. When refresh is required, the image data is read from memory 110 and converted into corresponding data voltages for output to display screen 104. As long as display driver circuit 102 can receive synchronization signals to determine the transmission timing of display data and receive partial image data of a frame from host device 100 for partial refresh, related implementations are within the scope of the present invention.

[0065] Figure 6 This is a data transmission method and a refresh method in the display system 10 when the image frame does not change according to an embodiment of the present invention. Figure 7 Based on Figure 6 The timing diagram of the signals and data transmitted between the host device 100 and the display driver circuit 102 under the data transmission mode of FIG. In this example, the host device 100 can determine whether the image data of each image frame is exactly the same as that of the previous image frame. When it is determined that the image data of image frame N+1 is exactly the same as that of the previous image frame N, all image data transmission during the frame period of image frame N+1 can be stopped. Correspondingly, all areas of the display screen 104 on image frame N+1 are not refreshed. In other words, the image displayed on the display screen 104 on image frame N+1 is exactly the same as the image displayed on image frame N, so the display driver circuit 102 does not output any data voltage to the display screen 104 during the frame period of image frame N+1.

[0066] Similarly, in order to further reduce power consumption, the host device 100 can selectively stop outputting the horizontal synchronization signal HSYNC to the display driving circuit 102, and the display driving circuit 102 receives the external horizontal synchronization signal EXT_HSYNC to perform timing control. Figure 7 As shown, in one embodiment (Option 1), the host device 100 can still transmit the vertical synchronization signal VSYNC to the display driver circuit 102 to determine the frame period of image frame N+1, and can also cause the transmission channel to enter a power-saving state (e.g., LP-11) during the frame period of image frame N+1. Specifically, the transmission channel is in the power-saving state during the vertical back corridor VBP, the data transmission period, and the vertical front corridor VFP. In another embodiment (Option 2), to achieve ultimate power saving, the host device 100 further stops outputting the vertical synchronization signal VSYNC to the display driver circuit 102. In this case, the frame period of the original image frame N+1 can be considered an extension of the vertical front corridor VFP of the previous frame N.

[0067] like Figure 7 As shown, in this example, the host device 100 may also selectively send a command to the display driver circuit 102 to instruct the display driver circuit 102 to stop transmitting all image data in the image frame N+1, or the display driver circuit 102 may determine whether to stop receiving image data according to the status of the transmission interface.

[0068] Figure 8 This is another embodiment of the present invention showing the data transmission method and refresh method in the system 10. Figure 9 Based on Figure 8 A timing diagram of signals and data transmitted between the host device 100 and the display driver circuit 102 under the data transmission mode of FIG. In this example, of the regions Z1 to Z3 of the display screen 104, only region Z2 needs to be refreshed, while regions Z1 and Z3 do not. Assuming that the image data range corresponding to the pixel rows in region Z2 is data rows L50 to L69, the host device 100 can transmit data rows slightly larger than the image data range to be refreshed (e.g., L20 to L99) to the display driver circuit 102 so that the display driver circuit 102 can perform necessary image processing. As described above, before the display screen 104 is refreshed, the display driver circuit 102 must first perform various image processing operations on the image data to enhance the visual effect (e.g., through the image processing circuit 114). During the image processing process, a larger range of original image data may need to be referenced. Even if the panel area corresponding to this additional image data itself is not refreshed, the host device 100 still needs to transmit this image data to the display driver circuit 102 to optimize the image processing effect.

[0069] like Figure 8 As shown, although only the pixel rows in zone Z2 need to be refreshed, the host device 100 still transmits part of the image data in zone Z1 and / or Z3 (e.g., image data close to zone Z2). In this case, the image processing circuit 114 in the display driver circuit 102 can refer to this additional received image data to perform image processing on the image data in zone Z2.

[0070] In one embodiment, the display driver circuit 102 may transmit relevant information in advance to the host device 100 based on the image data range to be referenced by its internal image processing. Therefore, the host device 100 can transmit corresponding additional image data rows during the data transmission period according to the needs of the display driver circuit 102. The range of the data rows is not limited to the examples described in this specification.

[0071] Furthermore, the unrefreshed image data in regions Z1 and Z3 generally has the same data content as the image data in a previous frame and is therefore stored in memory 110 before the previous frame is displayed. Therefore, in one embodiment, when image processing is performed on the image data in the refreshed region Z2, partial image data in regions Z1 and / or Z3 (e.g., image data near region Z2) may be retrieved from memory 110 for reference.

[0072] It is worth noting that in the above embodiment, there is only one refresh area on the display screen 104. However, in other embodiments, the refresh area on the display screen can be arbitrarily set based on changes in display data and can be located anywhere on the panel, and a frame of the image is not limited to having only one refresh area. Figure 10 This is another embodiment of the present invention showing the data transmission method and refresh method in the system 10. Figure 11 Based on Figure 10 The timing diagram of the signals and data transmitted between the host device 100 and the display driver circuit 102 under the data transmission mode is shown in FIG. In this example, in areas Z1 to Z3 of the display screen 104, areas Z1 and Z3 are refreshed, while area Z2 is not. Correspondingly, on the mobile industry processor interface between the host device 100 and the display driver circuit 102, the data lines transmitted are L0 to L49 (corresponding to area Z1) and L70 to L127 (corresponding to area Z3). During the transmission period for data lines L50 to L69, image data transmission is stopped and the system enters a power-saving state. The power-saving method is similar to that of the previous embodiment and will not be repeated here.

[0073] Figure 12 This is another embodiment of the present invention showing the data transmission method and refresh method in the display system 10. Figure 13 Based on Figure 12 The timing diagram of the signals and data transmitted between the host device 100 and the display driver circuit 102 under the data transmission mode is shown in FIG. In this example, the area Z2 is refreshed while the areas Z1 and Z3 are not refreshed. In order to save the transmission time of the display data, the transmission period corresponding to the unrefreshed image data range can be omitted. In detail, as shown in FIG. Figure 13 As shown, during the frame period of image frame N+1, the transmission period of the unrefreshed data lines L0-L49 and L70-L127 is omitted, and the vertical back corridor VBP and vertical front corridor VFP are also omitted. In this case, data lines L50-L69 can be transmitted in advance, thereby shortening the frame period and improving data transmission efficiency.

[0074] Similarly, in order to further reduce power consumption, the host device 100 can stop outputting the horizontal synchronization signal HSYNC to the display driver circuit 102, and the display driver circuit 102 receives the external horizontal synchronization signal EXT_HSYNC to perform timing control. In addition, the host device 100 can selectively transmit relevant instructions to the display driver circuit 102 before the frame period of the image frame N+1 to indicate the situation where the transmission time is omitted. It should be noted that in this example, since the display driver circuit 102 receives the data rows L50~L69 in advance, it can write the data rows L50~L69 to the memory 110, so that the data can be read out from the memory 110 when the panel is refreshed later. In this case, the switch 112_2 should be turned on and the switch 112_1 should be turned off, as shown in FIG. Figure 12 shown.

[0075] In the above embodiment, the display screen 104 is partitioned in the Y direction (vertical direction) to determine whether each area is refreshed or not, that is, the refresh determination is made on a per-row basis. However, in other embodiments, the display screen 104 may be partitioned in the X direction (horizontal direction), that is, the refresh determination is made on a per-row basis for one or more pixels in a row, thereby enabling more flexible local refresh applications. The host device 100 can transmit the image data to be refreshed to the display driver circuit 102 at the corresponding transmission time based on the X-direction and Y-direction partitioning schemes.

[0076] Figure 14 A data transmission method for adding X-direction partition refresh to the embodiment of the present invention. Figure 14 As shown, the image data for the area to be refreshed is located in rows 51 to 70, so the timing diagram for these rows is enlarged for ease of illustration. Specifically, a pulse of the horizontal synchronization signal HSYNC (or the external horizontal synchronization signal EXT_HSYNC) is used to determine a row time, and each row time is used to transmit a row of data. Each row time includes a horizontal back porch HBP, a data transmission period, and a horizontal front porch HFP.

[0077] If a pure Y-direction partitioning scheme is employed, the host device 100 can transmit all data rows L50-L69 in the area to be refreshed to the display driver circuit 102, and the display screen 104 can refresh the corresponding entire row of pixels. If X-direction partitioning is employed, the host device 100 only needs to transmit the image data within the area to be refreshed, namely, the portion of the image data within data rows L50-L69 to be refreshed. The display driver circuit 102 can control the activation and deactivation of the data lines (source lines) and scan lines (gate lines) to cause the display screen 104 to update the image in only a portion of the area. In this scenario, the transmission interface can be controlled to enter a power-saving state during the transmission period corresponding to other non-refreshed areas. In one embodiment, if a mobile processor interface is used for data transmission between the host device 100 and the display driver circuit 102, during periods when image data is not being transmitted, the transmission channel can be controlled to output a fixed data value of 0 or a fixed data value to reduce signal switching within the transmission channel. This way, image data is transmitted only during the transmission period corresponding to the area to be refreshed (i.e., the portion of the transmission period within a row), minimizing power consumption of the transmission interface.

[0078] It is worth noting that in the aforementioned embodiment, the LP-11 power saving state is adopted on the transmission interface during the transmission period when no image data is transmitted. Figure 14 The embodiment uses the method of outputting data 0 (or outputting a fixed data) to reduce power consumption. This is because according to the protocol of the mobile industry processor interface, entering the power saving state of LP-11 requires a mode conversion process and consumes a long time. Figure 14 In one embodiment, image data transmission for only a portion of pixels within a row of pixels is stopped. This stoppage may be extremely short, insufficient to cause the transmission interface to enter the LP-11 power-saving state. In this case, outputting fixed data values ​​can be used to reduce switching. In another embodiment, if the image data stoppage period is sufficiently long, LP-11 or other suitable power-saving methods can also be used. Regarding the periods of the front and rear horizontal / vertical back corridors or front and rear horizontal / vertical front corridors, the host device 100 can choose to output fixed data 0, set them to enter LP-11, or use other suitable power-saving methods based on their lengths. All related implementations are within the scope of the present invention.

[0079] Figure 15 Another data transmission method for adding X-direction partition refresh is provided in the embodiment of the present invention. Figure 15 Examples and Figure 14 The difference between the embodiments is that Figure 15This embodiment further utilizes data compression to perform panel refresh and corresponding data transmission. Due to bandwidth limitations of mobile processor interfaces, supporting the massive amounts of data required by currently available high-resolution displays requires that the host device 100 compress the display data before transmitting it. The display driver circuit 102 then decompresses the received display data, restoring it to its original form for subsequent image processing and / or writing to the display screen 104. Compression / decompression can reduce the amount of data transmitted by the mobile processor interface, meeting bandwidth requirements while also lowering power consumption during data transmission.

[0080] Currently, display data compression mostly uses Display Stream Compression (DSC) technology. Its compression architecture involves two decoders (or decompressors) within the display driver circuit 102: one decoder processes image data for the left half of the display screen 104, and the other processes image data for the right half. For example, assuming the display screen 104 includes 128 columns of pixels, one decoder processes pixels in columns 1 to 64, while the other processes pixels in columns 65 to 128. In this scenario, the host device 100 performs compression according to the same rules: compressing every 64 columns and N rows of pixels (N can be any positive integer within the total number of rows). In the DSC specification, the unit of compression is called a slice, and the size of the compression unit is determined by the slice width and slice height. In this example, the slice width is 64 and the slice height is N.

[0081] Under the above-mentioned compression scheme, the minimum unit of display data transmitted by the host device 100 is a segment, whose width is equal to half the total number of columns of the display screen 104. Even if the area that needs to be refreshed due to a change in the image is smaller than the segment size, the host device 100 still needs to compress the image data of the entire segment before transmitting it to the display driver circuit 102. The display driver circuit 102 can then perform decompression to restore the original data. In other words, a segment transmitted by the host device 100 may include a portion of image data to be refreshed and a portion of image data not to be refreshed. The encoder (or compressor) built into the host device 100 can combine these image data for compression and then transmit the compressed data to the display driver circuit 102 via the mobile industry processor interface. Correspondingly, the decoder in the display driver circuit 102 can decompress the compressed data (i.e., the segment) from the host device 100 to restore it to the portion of image data to be refreshed and the portion of image data not to be refreshed.

[0082] like Figure 15As shown, when X-direction partitioning is added, for the data rows L50-L69 where the area to be refreshed is located, the image data transmitted through the transmission interface is the part covered by the segment width SL_W, which is the left half of the panel in this example. Figure 15 In the embodiment, the transmitted image data is part of the image data in the data rows L50 to L69, but in other embodiments, if the segment height exceeds the range of the data rows L50 to L69, the image data compressed and transmitted through the transmission interface needs to extend to the upper row and / or lower row in accordance with the range of the segment height.

[0083] It is worth noting that the primary purpose of the present invention is to provide a data transmission method that can be used in a transmission interface between a display driver circuit and a host device to achieve partial refresh of display data. Those skilled in the art may modify or alter the present invention accordingly, without limitation. For example, in an embodiment of the present invention, image data transmission can be stopped during the transmission period corresponding to image data in an unrefreshed area to achieve power saving. This stopping of transmission can be achieved by any means, such as utilizing the channel status LP-11 of the mobile processor interface to stop data signal switching, outputting fixed data, or combining various transmission interface power saving modes to reduce power consumption. Such power saving implementations should not limit the scope of the present invention. Furthermore, in the above-described embodiment, the display driver circuit 102 is provided with a memory 110 serving as a frame buffer. Therefore, in addition to supporting the video mode of the mobile processor interface according to the timing determined by the vertical / horizontal synchronization signals, it can also support command mode or hybrid mode applications, and flexibly switch between the various operating modes through control of a switch. In another embodiment, the display driver circuit may also only support the video mode. In this case, the display driver circuit can receive the image data of the portion to be refreshed from the host device when the panel is to be refreshed. There is no need to set up a frame buffer, which can further save circuit area and reduce the power consumption required for memory reading and writing.

[0084] The above-mentioned data transmission method for the display driving circuit can be summarized into a data transmission process 160, such as Figure 16 The data transmission process 160 can be implemented in a display driving circuit in a display system, such as Figure 1 The display driving circuit 102 can transmit data to a host device via a transmission interface to partially refresh the display screen. Figure 16 As shown, the data transmission process 160 includes the following steps:

[0085] Step 1602: Receive at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for a plurality of image data in an image frame.

[0086] Step 1604 : For a first image data to be refreshed among the plurality of image data, receive the first image data within a first transmission period corresponding to the first image data.

[0087] Step 1606 : For a second image data that is not to be refreshed among the plurality of image data, stop receiving the second image data during a second transmission period corresponding to the second image data.

[0088] On the other hand, the data transmission method of the host device can be summarized into another data transmission process 170, such as Figure 17 The data transmission process 170 can be implemented in a host device in a display system, such as Figure 1 The host device 100 can transmit data to a display driving circuit via a transmission interface to partially refresh the display screen. Figure 17 As shown, the data transmission process 170 includes the following steps:

[0089] Step 1702: Output at least one first synchronization signal, where the at least one first synchronization signal is used to determine a frame period for a plurality of image data in an image frame.

[0090] Step 1704 : For a first image data to be refreshed among the plurality of image data, transmit the first image data within a first transmission period corresponding to the first image data.

[0091] Step 1706 : For a second image data that is not to be refreshed among the plurality of image data, stop transmitting the second image data during a second transmission period corresponding to the second image data.

[0092] The detailed operations and variations of the data transmission processes 160 and 170 can be found in the description of the above paragraphs and will not be elaborated here.

[0093] In summary, the present invention provides a data transmission method for a transmission interface between a display driver circuit and a host device in a display system, for achieving partial refresh of display data. In an embodiment of the present invention, the display driver circuit can receive vertical / horizontal synchronization signals from the host device and / or an external horizontal synchronization signal from an external device to control the timing of image data transmission based on the synchronization signals, namely, setting a transmission period for each row of image data. For image data to be refreshed, the host device can transmit the image data to the display driver circuit during the corresponding transmission period, and the display driver circuit can receive the image data and drive the display screen to refresh accordingly. For image data not to be refreshed, the host device can stop transmitting the image data to the display driver circuit during the corresponding transmission period, and the display driver circuit stops receiving the image data. In this case, the display screen does not need to be refreshed. Through this data transmission method, only a portion of the image data to be refreshed is transmitted between the host device and the display driver circuit, so that the display screen only refreshes a portion of an image frame, thereby reducing power consumption of the transmission interface between the host device and the display driver circuit and power consumption of the display screen. In one embodiment, the host device can determine the range of the area to be refreshed based on the content of the image data to be transmitted and transmit the relevant information to the display driver circuit via a command. Alternatively, the display driver circuit can determine the range of image data to be refreshed and image data not to be refreshed based on the data transmission status of the transmission interface and control the display screen to perform a partial refresh accordingly, thereby achieving power conservation.

[0094] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A data transmission method for a display driving circuit, characterized in that: The data transmission method includes: receiving at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for a plurality of image data in an image frame; For a first image data to be refreshed among the plurality of image data, receiving the first image data within a first transmission period corresponding to the first image data; and For a second image data that is not refreshed among the plurality of image data, the receiving of the second image data is stopped during a second transmission period corresponding to the second image data.

2. The data transmission method according to claim 1, wherein: The frame period determined by the at least one first synchronization signal includes a data transmission period, a front corridor, and a back corridor, wherein the first transmission period and the second transmission period are located within the data transmission period.

3. The data transmission method according to claim 1, wherein: Also includes: stopping receiving a first synchronization signal of the at least one first synchronization signal from a host device during the second transmission period; as well as A second synchronization signal is received from an external device, and the first transmission period and the second transmission period are determined by using the second synchronization signal.

4. The data transmission method according to claim 1, wherein: The display driving circuit receives the first image data through a transmission interface, and during the second transmission period, the transmission interface is set to a power saving state.

5. The data transmission method according to claim 1, wherein: Also includes: When the first image data is refreshed, a data voltage corresponding to the first image data is output to a display screen; as well as When the second image data is not refreshed, outputting any data voltage to the display screen is stopped.

6. The data transmission method according to claim 1, wherein: The plurality of image data includes a plurality of first image data and a plurality of second image data, and the data transmission method further includes: Before the frame period, receiving a command from a host device; and The ranges of the plurality of first image data and the plurality of second image data are determined according to the instruction.

7. The data transmission method according to claim 1, wherein: The display driving circuit is configured to receive the plurality of image data through a transmission interface, the plurality of image data including a plurality of first image data and a plurality of second image data, and the data transmission method further comprises: The ranges of the plurality of first image data and the plurality of second image data are determined according to the state of the transmission interface.

8. The data transmission method according to claim 1, wherein: Also includes: In addition to receiving the first image data during the first transmission period, a third image data which is not refreshed among the plurality of image data is also received.

9. The data transmission method according to claim 8, wherein: Also includes: The third image data is referred to to perform image processing on the first image data.

10. The data transmission method according to claim 8, wherein: Also includes: A segment including the first image data and the third image data is decompressed.

11. A display driving circuit, characterized in that: Used to: receiving at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for a plurality of image data in an image frame; For a first image data to be refreshed among the plurality of image data, receiving the first image data within a first transmission period corresponding to the first image data; as well as For a second image data that is not refreshed among the plurality of image data, the receiving of the second image data is stopped during a second transmission period corresponding to the second image data.

12. A data transmission method for a host device, characterized in that: The data transmission method includes: Outputting at least one first synchronization signal, wherein the at least one first synchronization signal is used to determine a frame period for a plurality of image data on a first image frame; For a first image data to be refreshed among the plurality of image data, transmitting the first image data within a first transmission period corresponding to the first image data; and For a second image data that is not refreshed among the plurality of image data, the transmission of the second image data is stopped during a second transmission period corresponding to the second image data.

13. The data transmission method according to claim 12, wherein: The frame period determined by the at least one first synchronization signal includes a data transmission period, a front corridor, and a back corridor, wherein the first transmission period and the second transmission period are located within the data transmission period.

14. The data transmission method according to claim 12, wherein: The at least one first synchronization signal and the first image data are transmitted to a display driving circuit.

15. The data transmission method according to claim 14, wherein: Also includes: During the second transmission period, transmission of a first synchronization signal among the at least one first synchronization signal to the display driving circuit is stopped.

16. The data transmission method according to claim 12, wherein: The host device transmits the first image data via a transmission interface, and during the second transmission period, the transmission interface is set to a power saving state.

17. The data transmission method according to claim 12, wherein: Also includes: When it is determined that a plurality of image data of a second image frame following the first image frame is identical to the plurality of image data of the first image frame, transmission of the plurality of image data of the second image frame is stopped during another frame period corresponding to the second image frame.

18. The data transmission method according to claim 17, wherein: Also includes: The output of the at least one first synchronization signal is stopped during the other frame period corresponding to the second image frame.

19. The data transmission method according to claim 12, wherein: The plurality of image data includes a plurality of first image data and a plurality of second image data, and the data transmission method further includes: Before the frame period, a command is output to a display driving circuit to indicate the ranges of the plurality of first image data and the plurality of second image data.

20. The data transmission method according to claim 12, wherein: Also includes: In addition to transmitting the first image data during the first transmission period, a third image data which is not refreshed among the plurality of image data is also transmitted.

21. The data transmission method according to claim 12, wherein: Also includes: The first image data and the third image data are combined to be compressed, and the compressed first image data and the third image data are transmitted.

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