Patent Publication Number: US-11640780-B2

Title: Data driver circuit correcting skew between a clock and data

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the Korean Patent Application No. 10-2020-0175283 filed on Dec. 15, 2020, which is hereby incorporated by reference as if fully set forth herein. 
     FIELD OF THE INVENTION 
     The present disclosure relates to a data driver circuit capable of correcting a skew between a clock and data even when a frequency and the number of channels are increased. 
     BACKGROUND 
     Display devices include a panel configured to display an image through a pixel matrix, a gate driver circuit configured to drive gate lines of the panel, a data driver circuit configured to supply a data signal to data lines of the panel, a timing controller configured to control the gate driver circuit and the data driver circuit, and the like. 
     The data driver circuit may sequentially latch image data supplied from the timing controller for each horizontal period, simultaneously convert the pieces of latched data of each horizontal line into analog data signals, and individually output the converted data signals to the data lines of the panel. 
     As the display devices are developed toward having high resolution, a driving frequency of the data driver circuit and the number of output channels need to be increased. 
     However, when a length of a chip increases due to the increase of the number of output channels, a length of a data path in a channel area increases to cause a skew problem between a clock and data to occur, resulting in a data sampling error, and thus there is a limitation in increasing the frequency. 
     SUMMARY 
     The present disclosure is directed to providing a data driver circuit capable of overcoming a limitation in frequency by correcting a skew between a clock and data even when a frequency and the number of channels are increased. 
     According to an aspect of the present disclosure, there is provided a data driver circuit including a shift register configured output sampling signals in response to a clock, a first latch part configured to sample and latch data of each channel in response to each of the sampling signals, and a bi-directional deskew buffer part disposed between a stage of a first channel and a stage of a second channel belonging to the shift register and between a first latch of a first channel and a first latch of a second channel belonging to the first latch part, and configured to buffer a clock input from the stage of the first channel to output the buffered clock to the stage of the second channel, and buffer and latch data of the second channel input after data of the first channel, which is latched by the first latch of the first channel, in synchronization with the buffered clock to output the latched data to the first latch of the second channel. 
     The bi-directional deskew buffer part may include a clock buffer configured to buffer the clock supplied from the stage of the first channel of the shift register and output the buffered clock to the stage of the second channel, and a data buffer part configured to buffer and latch the data of the second channel input through the first latch of the first channel of the first latch part in synchronization with the clock output from the clock buffer, and output the latched data to the first latch of the second channel. 
     Each of the clock buffer, and data buffers of a plurality of bits constituting the data buffer part may include an input switch part including a first switch and a second switch connected in series between a first supply line and a second supply line and configured to determine an input direction or a latch operation, an output switch part including a third switch and a fourth switch connected in series between the first and second supply lines and configured to determine an output direction or the latch operation, and a buffer part connected between a first connection node between the first and second switches and a second connection node between the third and fourth switches. 
     The shift register and the first latch part may be divided into a plurality of channel blocks, and the bi-directional deskew buffer part may be disposed between the plurality of channel blocks. The plurality of channel blocks of the shift register and the first latch part, and the bi-directional deskew buffer part between the plurality of channel blocks may be sequentially activated from an inactivated state. When the first latch part latches all pieces of data of the plurality of channel blocks, the plurality of channel blocks and the bi-directional deskew buffer part may be inactivated. 
     The data driver circuit may further include a second latch part configured to simultaneously receive and latch pieces of data of a plurality of channels, which are latched in the first latch part, and output the latched pieces of data in response to a load signal, wherein the clock buffer of the bi-directional deskew buffer part may be enabled in response to a carry signal received from the stage of the first channel of the shift register and may be disabled in response to the load signal of the second latch part, and the data buffer part of the bi-directional deskew buffer part may be enabled or disabled according to an output of the clock buffer. 
     The clock buffer may include an input switch part including a 1Ath switch and a 2Ath switch connected in series between a first clock supply line connected to the stage of the first channel of the shift register and a second clock supply line connected to the stage of the second channel of the shift register, an output switch part including a 3Ath switch and a 4Ath switch connected in series between the first and second clock supply lines, a buffer part connected between a 1Ath connection node between the 1Ath and 2Ath switches and a 2Ath connection node between the 3Ath and 4Ath switches, and an SR latch circuit configured to receive and latch the carry signal received from the stage of the first channel and the load signal respectively as a set signal and a reset signal and output the set signal and the reset signal to the buffer part. 
     The buffer part of the clock buffer may include a 1Ath inverter connected to the 1Ath connection node, and a NAND gate circuit configured to receive an output of the 1Ath inverter and an output of the SR latch circuit, perform a NAND gate logic operation, and output an operation result to the 2Ath connection node, and may further include a 2Ath inverter configured to receive an output of the 2Ath connection node, generate a data enable signal, and output the data enable signal to the data buffer. 
     Each of the data buffers of a plurality of bits constituting the data buffer part may include an input switch part including a 1Bth switch and a 2Bth switch connected in series between a first data supply line connected to a data bus passing through the first latch of the first channel and a second data supply line connected to the first latch of the second channel, an output switch part including a 3Bth switch and a 4Bth switch connected in series between the first and second data supply lines, and a buffer part including a 1Bth inverter and a 2Bth inverter connected in series between a 1Bth connection node between the 1Bth and 2Bth switches and a 2Bth connection node between the 3Bth and 4Bth switches. 
     The data driver circuit may include a channel area in which the shift register, the first latch part, the bi-directional deskew buffer part, a second latch part, a digital-to-analog converter, and an output buffer part are disposed, an output pad area configured to output data signals supplied from the channel area to a plurality of output channels, an input pad area configured to receive a transmission signal, a receiver disposed adjacent to the input pad area, and configured to receive the transmission signal through the input pad area, and recover the clock, the data, and a control signal from the received transmission signal to output the recovered clock, data, and control signal, and a logic controller disposed adjacent to and between the receiver and the channel area, and configured to transmit the clock and the control signal supplied from the receiver to the channel area and rearrange the data for each channel to supply the data to the channel area. 
     The logic controller may include a first logic controller and a second logic controller disposed respectively adjacent to both side surface portions of the channel area with the channel area therebetween. The receiver may include a first receiver and a second receiver disposed respectively adjacent to the first and second logic controllers. The input pad area may include a first input pad area and a second input pad area disposed on both side surface portions of the data driver circuit to be adjacent to the first and second receivers, respectively. The output pad area may be disposed at a lower end portion of each of the input pad area, the receiver, the logic controller, and the channel area. 
     According to another aspect of the present disclosure, there is provided a data driver circuit including a bi-directional deskew buffer part disposed between a stage of a first channel and a stage of a second channel belonging to a shift register and between a first latch of a first channel and a first latch of a second channel belonging to a first latch part, wherein the bi-directional deskew buffer part may include a clock buffer configured to buffer a clock input from the stage of the first channel and output the buffered clock to the stage of the second channel, and a data buffer part configured to buffer and latch data of the second channel input after data of the first channel, which is latched by the first latch of the first channel, in synchronization with a clock output from the clock buffer, and output the latched data to the first latch of the second channel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure. In the drawings: 
         FIG.  1    is a block diagram illustrating a configuration of a display device according to one embodiment; 
         FIG.  2    is a block diagram illustrating a display device having data driver integrated circuits (ICs) according to one embodiment; 
         FIG.  3    is a block diagram illustrating an internal configuration of the data driver IC according to one embodiment; 
         FIG.  4    is a block diagram illustrating an arrangement structure of the data driver IC according to one embodiment; 
         FIG.  5    is an equivalent circuit diagram illustrating an internal configuration of a bi-directional deskew buffer according to one embodiment; 
         FIGS.  6 A and  6 B  are diagrams illustrating a bi-directional buffering operation of the bi-directional deskew buffer according to one embodiment; 
         FIGS.  7 A and  7 B  are diagrams illustrating a bi-directional latch operation of the bi-directional deskew buffer (BDB) according to one embodiment; 
         FIG.  8    is a block diagram illustrating a partial configuration of a shift register and a latch part of the data driver IC having a BDB part according to one embodiment; 
         FIG.  9    is a timing diagram illustrating input/output signals of a clock buffer and a data buffer according to one embodiment; 
         FIG.  10    is a diagram illustrating a principle of reducing power consumption of the data driver IC according to one embodiment; 
         FIG.  11    is a block diagram illustrating a partial configuration of a shift register and a latch part of a data driver IC according to one embodiment; 
         FIG.  12    is a timing diagram illustrating input/output signals of a BDB part in a non-active state and an active state in the data driver IC according to one embodiment; and 
         FIG.  13    is an equivalent circuit diagram illustrating an internal configuration of a clock buffer and a data buffer according to one embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Advantages and features of the present disclosure, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Further, the present disclosure is only defined by scopes of claims. 
     A shape, a size, a ratio, an angle, and a number disclosed in the drawings for describing embodiments of the present disclosure are merely an example, and thus, the present disclosure is not limited to the illustrated details. Like reference numerals refer to like elements throughout the specification. In the following description, when the detailed description of the relevant known function or configuration is determined to unnecessarily obscure the important point of the present disclosure, the detailed description will be omitted. 
     In a case where ‘comprise’, ‘have’, and ‘include’ described in the present specification are used, another part may be added unless ‘only’ is used. The terms of a singular form may include plural forms unless referred to the contrary. 
     In construing an element, the element is construed as including an error range although there is no explicit description. 
     In describing a position relationship, for example, when a position relation between two parts is described as “on,” “over,” “under,” and “next,” one or more other parts may be disposed between the two parts unless a more limiting term, such as “just” or “direct(ly)” is used. 
     In describing a time relationship, for example, when the temporal order is described as, for example, “after,” “subsequent,” “next,” and “before,” a case which is not continuous may be included unless a more limiting term, such as “just,” “immediate(ly),” or “direct(ly)” is used. 
     It will be understood that, although the terms “first,” “second,” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. 
     In describing the elements of the present disclosure, the terms “first,” “second,” “A,” “B,” “(a),” “(b),” etc., may be used. These terms are intended to identify the corresponding elements from the other elements, and basis, order, or number of the corresponding elements should not be limited by these terms. The expression that an element is “connected,” “coupled,” or “adhered” to another element or layer, the element or layer can not only be directly connected or adhered to another element or layer, but also be indirectly connected or adhered to another element or layer with one or more intervening elements or layers “disposed” between the elements or layers, unless otherwise specified. 
     The term “at least one” should be understood as including any and all combinations of one or more among the associated listed elements. For example, the meaning of “at least one or more of a first element, a second element, and a third element” denotes the combination of all elements proposed from two or more of the first element, the second element, and the third element as well as the first element, the second element, or the third element. 
     Features of various embodiments of the present disclosure may be partially or overall coupled to or combined with each other, and may be variously inter-operated with each other and driven technically as those skilled in the art can sufficiently understand. The embodiments of the present disclosure may be carried out independently from each other, or may be carried out together in co-dependent relationship. 
     Hereinafter, exemplary embodiments of the present disclosure will be described in detail with reference to the drawings. 
       FIG.  1    is a block diagram schematically illustrating a configuration of a display device according to one embodiment,  FIG.  2    is a diagram illustrating a display device having a plurality of data driver integrated circuits (ICs) according to one embodiment,  FIG.  3    is a block diagram illustrating an internal configuration of the data driver IC according to one embodiment, and  FIG.  4    is a block diagram illustrating an arrangement structure of the data driver IC according to one embodiment. 
     The display device according to one embodiment may be any one of various display devices including a liquid crystal display device, an electroluminescent display device, a micro light-emitting diode (LED) display device, and the like. The electroluminescent display device may be an organic light-emitting diode (OLED) display device, a quantum-dot light-emitting diode display device, or an inorganic light-emitting diode display device. 
     Referring to  FIG.  1   , the display device may include a display panel  100 , a gate driver  200 , a data driver  300 , a gamma voltage generator  500 , a timing controller  400 , and the like. The gate driver  200  and the data driver  300  may be defined as panel drivers. The gate driver  200 , the data driver  300 , and the timing controller  400  may be defined as display drivers. 
     The display panel  100  displays an image through a display area DA in which sub-pixels P are arranged in a matrix form. Each of the sub-pixels P is one of a red sub-pixel emitting red light, a green sub-pixel emitting green light, a blue sub-pixel emitting blue light, and a white sub-pixel emitting white light, and is independently driven by at least one thin-film transistor (TFT). A unit pixel may be configured of a combination of two, three, or four sub-pixels having different colors. 
     A gate electrode of the TFT belonging to each of the sub-pixels P is connected to the gate driver  200  through a gate line disposed on the display panel  100 , and an input electrode of any one of a source electrode and a drain electrode of each TFT is connected to the data driver  300  through a data line disposed on the display panel  100 . 
     In other words, in each of the sub-pixels P, while the TFT is turned-on in response to a scan pulse of a gate-on voltage, which is supplied through the corresponding gate line from the gate driver  200 , a pixel voltage (driving voltage) corresponding to the data signal is charged by receiving the data signal, which is supplied through the corresponding data line from the data driver  300 , through the turned-on TFT and light corresponding to the charged voltage is emitted, so that a grayscale corresponding to the data signal may be expressed. 
     The display panel  100  may further include a touch sensor screen entirely overlapping the display area and configured to sense a touch of a user, and the touch sensor screen may be embedded in the panel  100  or disposed in the display area of the panel  100 . 
     The timing controller  400  may receive image data and synchronization signals from a host system (not shown). For example, the host system may be any one of a computer, a TV system, a set-top box, a system of a portable terminal such as a tablet or mobile phone. The synchronization signals may include a dot clock, a data enable signal, a vertical synchronization signal, a horizontal synchronization signal, and the like. 
     The timing controller  400  may generate a plurality of data control signals to supply the plurality of data control signals to the data driver  300  using the received synchronization signals and timing setting information (start timing, a pulse width, and the like) stored in an internal register, and generate a plurality of gate control signals to supply the plurality of gate control signals to the gate driver  200 . 
     The timing controller  400  may perform various types of image processing such as brightness correction for reducing power consumption, image quality correction, and the like on the supplied image data, and supply the image-processed data to the data driver  300 . 
     The gamma voltage generator  500  may generate a reference gamma voltage set including a plurality of reference gamma voltages having different voltage levels and supply the reference gamma voltage set to the data driver  300 . The gamma voltage generator  500  may generate the plurality of reference gamma voltages corresponding to gamma characteristics of the display device under the control of the timing controller  400  and supply the reference gamma voltages to the data driver  300 . The gamma voltage generator  500  may include a programmable gamma IC, and may receive gamma data from the timing controller  400 , generate or adjust a reference gamma voltage level according to the gamma data, and output the reference gamma voltage level to the data driver  300 . 
     The gate driver  200  is controlled according to the plurality of gate control signals supplied from the timing controller  400  to individually drive the gate lines of the display panel  100 . The gate driver  200  may sequentially drive a plurality of gate lines. The gate driver  200  may supply a scan signal of a gate-on voltage to the corresponding gate line in a driving period of each of the gate lines, and supply the scan signal of a gate-off voltage to the corresponding gate line in a non-driving period of each of the gate lines. 
     The gate driver  200  may include at least one gate driver IC, and may be mounted on a circuit film such as a tape carrier package (TCP), a chip on film (COF), a flexible printed circuit (FPC), or the like to be attached to the display panel  100  in a tape automatic bonding (TAB) manner, or may be mounted on the display panel  100  in a chip on glass (COG) manner. Alternatively, the gate driver  200  may be formed on a TFT substrate together with the TFT belonging to each of the sub-pixels P of the display panel  100  and embedded in a bezel area of the display panel  100 . 
     The data driver  300  may be controlled according to the data control signal supplied from the timing controller  400 , and may convert the digital image data supplied from the timing controller  400  into an analog data signal and supply the analog data signal to each of the data lines of the display panel  100 . The data driver  300  may convert the digital image data into the analog data signal using grayscale voltages obtained by subdividing the plurality of reference gamma voltages supplied from the gamma voltage generator  500 . 
     The data driver  300  may include at least one data driver IC and may be mounted on a circuit film such as a TCP, a COF, an FPC, or the like to be attached to the display panel  100  in a TAB manner, or may be mounted in the bezel area of the display panel  100  in a COG manner. 
     Referring to  FIG.  2   , the data driver  300  may include a plurality of data driver ICs (D-ICs)  600 , and may be located between a printed circuit board (PCB)  800 , on which the timing controller  400  ( FIG.  1   ) and the gamma voltage generator  500  ( FIG.  1   ) are mounted, and the display panel  100  and connected to the PCB  800  and display panel  100 . 
     Each of the plurality of data driver ICs  600  may receive a transmission signal, which is supplied from the PCB  800 , through any one of input parts respectively located on both left and right side surface portions thereof, and may output data signals to the display panel  100  through an output part located at a lower end portion thereof. Meanwhile, in each of the data driver ICs  600 , the input part may be located on one side surface portion rather than on both side surface portions, or may be located on an upper end portion. 
     Referring to  FIG.  3   , each of the data driver ICs  600  may include a receiver  630 , a shift register  660 , latch parts  670  and  680 , a grayscale voltage generator  652 , a digital to analog converter (DAC) part  690 , and an output buffer part  692 . 
     Each of the data driver ICs  600  may supply a corresponding data signal to m (where m is a positive integer) data lines among the data lines disposed on the display panel  100  through m output channels CH 1  to CHm. 
     In each of the data driver ICs  600 , the shift register  660 , the latch parts  670  and  680 , the DAC part  690 , and the output buffer part  692  may be disposed in a channel area, and the shift register  660 , the latch parts  670  and  680 , the DAC part  690 , and the output buffer part  692  may include m channels equal to the number of the output channels CH 1  to CHm. 
     In order to reduce the number of transmission lines and reduce electromagnetic interference (EMI), the timing controller  400  and the plurality of data driver ICs  600  may use a high-speed serial interface method in which image data and control signals are converted into serial transmission signals in which a clock is embedded and transmitted and received in a point-to-point manner. To this end, the timing controller  400  includes a transmitter, and each of the plurality of data driver ICs  600  includes the receiver  630 . The timing controller  400  may transmit the transmission signal in the form of a differential signal, such as a low voltage differential signal (LVDS), through at least one pair of transmission channels individually connected to the plurality of data driver ICs  600 . 
     The receiver  630  of each data driver IC  600  may receive the transmission signals in the form of a differential signal supplied from the timing controller  400  in a high-speed serial interface method, recover a clock from the received differential signal and also recover digital image data and control signals using the recovered clock, and output the recovered digital image data and control signals to a logic controller  640 . 
     The logic controller  640  may convert the image data supplied from the receiver  630  into a parallel form of each sub-pixel unit, rearrange the data of each sub-pixel according to an operation option, and output the rearranged data to a first latch part  670 . The logic controller  640  may output a start pulse and a clock signal to the shift register  660  using the clock and data control signals supplied from the receiver  630 , output a load signal to a second latch part  680  and the output buffer part  692 , and may further generate and output control signals necessary for the operations of other components. 
     The shift register  660  may sequentially output a plurality of sampling signals to the first latch part  670  while sequentially shifting the start pulse according to the clock signal. The shift register  660  may include stages of a plurality of channels and sequentially output sampling signals of a plurality of channels to the first latch part  670  while performing a shift operation for sequentially shifting the start pulse according to the clock signal. The shift register  660  may include stages of m channels equal to the number of the output channels CH 1  to CHm, and may include stages less than m stages. 
     The first latch part  670  may sequentially latch pieces of data of a plurality of channels, which are sequentially transmitted from the receiver  630  through a data bus, in response to the sampling signals of a plurality of channels, which are sequentially input from the shift register  660 , for each channel of each sub-pixel unit, and when pieces of data of all channels are latched, the first latch part  670  may simultaneously output the latched data of each channel to the second latch part  680 . The first latch part  670  may include first latches of m channels equal to the number of the output channels CH 1  to CHm. 
     The second latch part  680  may simultaneously output the data of each channel (sub-pixel) received from the first latch part  670  to the DAC part  690  in response to the load signal supplied from the logic controller  640 . The second latch part  680  may include second latches of m channels equal to the number of the output channels CH 1  to CHm. 
     The grayscale voltage generator  652  may subdivide the reference gamma voltages supplied from the gamma voltage generator  500  into a plurality of grayscale voltages respectively corresponding to grayscale values of the image data by dividing the reference gamma voltages through a resistor string, and then output the subdivided grayscale voltages to the DAC part  690 . 
     The DAC part  690  may convert the data of each subpixel supplied from the second latch part  680  into an analog data signal for each channel using the grayscale voltages supplied from the grayscale voltage generator  652 , and output the analog data signals to the output buffer part  692 . The DAC part  690  may include DACs of m channels equal to the number of the channels CH 1  to CHm. 
     The output buffer part  692  may buffer the data signal of each sub-pixel, which is supplied from the DAC part  690 , for each channel and output the buffered data signal to each of the plurality of output channels CH 1  to CHm. The output buffer part  692  may include output buffers of m channels equal to the number of output channels CH 1  to CHm. 
     Referring to  FIG.  4   , since the number of the output channels connected to the data lines of the display panel  100  is large, each of the data driver ICs  600  according to one embodiment may have a rectangular shape elongated in leftward and rightward directions, and an output pad area  620  may be disposed in a long area in the lower end portion of the data driver IC  600 . 
     In order for left and right bi-directional driving, each of the data driver ICs  600  may include first and second input pad areas  610 A and  6106  respectively disposed on left and right side surface portions thereof, and may include first and second receivers (RXs)  630 A and  630 B disposed respectively adjacent to the first and second input pad areas  610 A and  6106 , and first and second logic controllers  640 A and  640 B disposed respectively adjacent to the first and second receivers  630 A and  630 B. In addition, each of the data driver ICs  600  may include a channel area  650 , which is disposed between the first and second logic controllers  640 A and  640 B and thus driven in both directions and connected to the output pad area  620  at the lower end portion thereof. The shift register  660 , the latch parts  670  and  680 , the DAC part  690 , and the output buffer part  692 , which are described with reference to  FIG.  3   , may be disposed in the channel area  650 . 
     The data driver IC  600  may receive the transmission signal supplied from the timing controller  400  through one of the first and second input pad areas  610 A and  610 B according to an operation option. 
     The data driver IC  600  may convert the transmission signals input through the first input pad area  610 A into data of each sub-pixel to be transmitted to the channel area  650  through an A data path (a first data path) passing through the first receiver  630 A and the first logic controller  640 A in a first direction. The data driver IC  600  may sequentially sample and latch the data of each sub-pixel for each channel through a B data path (a second data path) passing through a first channel area  650 A and a second channel area  650 B from the first logic controller  640 A in the first direction, convert the latched data of each sub-pixel into a data signal, and output the data signal for each channel through the output pad area  620 . 
     Meanwhile, the data driver IC  600  may convert the transmission signals input through the second input pad area  610 B into data of each sub-pixel to be transmitted to the channel area  650  through the A data path (the first data path) passing through the second receiver  630 B and second logic controller  640 B in a second direction. The data driver IC  600  may sequentially sample and latch the data of each sub-pixel for each channel through the B data path (the second data path) passing through the second channel area  650 B and the first channel area  650 A from the second logic controller  640 B in the second direction, convert the latched data of each sub-pixel into a data signal, and output the data signal for each channel through the output pad area  620 . 
     In particular, in the data driver IC  600  according to one embodiment, in order to prevent a skew problem from occurring between a clock and data in the long channel area  650  as the number of output channels CH 1  to CHm increases, a bi-directional deskew buffer (BDB) part configured to synchronize the data using the clock is applied to each of the plurality of channels of the shift register  660  and the first latch part  670  in the channel area  650  so that the skew generated between the clock and the data may be offset. 
     To this end, the BDB part may include a clock buffer that is a bi-directional deskew buffer for a clock and a data buffer part that is a bi-directional deskew buffer for data. The channel area  650  may be divided into a plurality of channel blocks, and the clock buffer and the data buffer part of the BDB part may be disposed between adjacent channel blocks. The clock buffer may buffer and output a clock in both directions, and the data buffer part may buffer and latch data so that the data is synchronized with the clock supplied from the clock buffer and output the data, thereby offsetting the skew between the clock and the data. A detailed description thereof will be made below. 
       FIG.  5    is an equivalent circuit diagram illustrating an internal configuration of a BDB according to one embodiment, and  FIGS.  6 A and  6 B  are diagrams illustrating a bi-directional buffering operation of the BDB according to one embodiment, and  FIGS.  7 A and  7 B  are diagrams illustrating a bi-directional latch operation of the BDB according to one embodiment. 
     Referring to  FIG.  5   , the BDB according to one embodiment may include an input switch part  710  including first and second switches SW 1  and SW 2 , an output switch part  730  including third and fourth switches SW 3  and SW 4 , and a buffer part  720  including first and second inverters INV 1  and INV 2  between the input switch part  710  and the output switch part  730 . An switching operation of each of the first to fourth switches SW 1 , SW 2 , SW 3 , and SW 4  may be controlled by the logic controllers  640 A and  640 B ( 640 ). The internal circuit configuration of the BDB may be applied to each of the clock buffer and the data buffer part, and in this case, the input switch part  710  of the data buffer may be controlled by an output of the clock buffer. The data buffer part of one channel includes data buffers of a plurality of bits, which buffer and latch pieces of data of a plurality of bits in parallel, and the data buffer of each bit may be configured as an internal circuit illustrated in  FIG.  5   . 
     The first and second switches SW 1  and SW 2  of the input switch part  710  may be connected in series between first and second supply lines IO_L and IO_R, and may determine an input direction or a latch operation. 
     The third and fourth switches SW 3  and SW 4  of the output switch part  730  may be connected in series between the first and second supply lines IO_L and IO_R, and may determine an output direction or the latch operation. 
     The first and second inverters INV 1  and INV 2  of the buffer part  720  may be connected in series between a first connection node N 1  between the first and second switches SW 1  and SW 2  and a second connection node N 2  between the third and fourth switches SW 3  and SW 4 , and may buffer and output an input signal or may latch and output the input signal. 
     Referring to  FIG.  6 A , when the first and fourth switches SW 1  and SW 4  are turned-on, and the second and third switches SW 2  and SW 3  are turned-off, the input signal supplied through the left first supply line IO_L may be buffered through a first path passing through the first switch SW 1 , the first and second inverters INV 1  and INV 2 , and the fourth switch SW 4  in a first direction and output through the right second supply line IO_R. 
     Referring to  FIG.  6 B , when the first and fourth switches SW 1  and SW 4  are turned-off, and the second and third switches SW 2  and SW 3  are turned-on, the input signal supplied through the right second supply line IO_R may be buffered through a second path passing through the second switch SW 2 , the first and second inverters INV 1  and INV 2 , and the third switch SW 3  in a second direction and output through the left first supply line IO_L. 
     When the first and fourth switches SW 1  and SW 4  are turned-on and the second and third switches SW 2  and SW 3  are turned-off as shown in  FIG.  6 A , and then the first and third switches SW 1  and SW 3  are turned-off and the second and fourth switches SW 2  and SW 4  are turned-on as shown in  FIG.  7 A , the input signal supplied through the left first supply line IO_L may be buffered through the first path passing through the first switch SW 1 , the first and second inverters INV 1  and INV 2 , and the fourth switch SW 4  in the first direction as shown in  FIG.  6 A , and then latched through a third path passing through the second switch SW 2 , the first and second inverters INV 1  and INV 2 , and the fourth switch SW 4 , and the latched signal may be output through the right second supply line IO_R. 
     When the first and fourth switches SW 1  and SW 4  are turned-off and the second and third switches SW 2  and SW 3  are turned-on as shown in  FIG.  6 B  and then the second and fourth switches SW 2  and SW 4  are turned-off and the first and third switches SW 1  and SW 3  are turned-on as shown in  FIG.  7 B  in response to the control of the logic controllers  640 A and  640 B ( 640 ), the input signal supplied through the right second supply line IO_R may be buffered through the second path passing through the second switch SW 2 , the first and second inverters INV 1  and INV 2 , and the third switch SW 3  in the second direction as shown in  FIG.  6 B  and then latched through a fourth path passing through the first switch SW 1 , the first and second inverters INV 1  and INV 2 , and the third switch SW 3  as shown in  FIG.  7 B , and the latched signal may be output through the left first supply line IO_L. 
       FIG.  8    is a block diagram illustrating a partial configuration of a shift register and a latch part of the data driver IC having the BDB part according to one embodiment, and  FIG.  9    is a timing diagram illustrating input/output signals of a clock buffer and a data buffer according to one embodiment. 
     Referring to  FIG.  8   , the BDB part according to one embodiment may include a clock buffer  662 , which is disposed on a clock line between a stage STn−1 of an (n−1)th (n is an integer greater than or equal to 2) channel and a stage STn of an nth channel in the shift register  660 , and a data buffer part  672  disposed on a data bus between a first latch LA 1 ( n −1) of the (n−1)th channel and a first latch LA 1   n  of the nth channel in the first latch part  670 . 
     The clock buffer  662  of the BDB part may buffer an input clock CLK_L supplied through the stage STn−1 of the (n−1)th channel, and supply a buffered clock CLK_R to the stage STn of the nth channel as a clock signal. 
     The data buffer part  672  of the BDB part may buffer and latch data of the nth channel, which is transmitted after data of the (n−1)th channel through the data bus passes through the first latch LA 1 ( n −1) of the (n−1)th channel, in synchronization with the output clock CLK_R of the clock buffer  662 , and supply the data of the nth channel, which is synchronized with the output clock CLK_R of the clock buffer  662 , to the first latch LA 1   n  of the nth channel. The data buffer part  672  of the BDB part may include k-bit data buffers  672  (k is a positive integer) that respectively buffer and latch k bits of the corresponding channel (sub-pixel) data and output the latched k bits. 
     In the shift register  660 , the stage STn−1 of the (n−1)th channel may output the sampling signal of the (n−1)th channel to the first latch LA 1 ( n −1) of the (n−1)th channel in response to the input clock CLK_L, and the stage STn of the nth channel may output the sampling signal to the first latch LA 1   n  of the nth channel in response to the clock CLK_R buffered through the clock buffer  662 . 
     The first latch LA 1 ( n −1) of the (n−1)th channel may sample and latch the data of the (n−1)th channel in response to the sampling signal supplied from the stage STn−1 of the (n−1)th channel. The first latch LA 1   n  of the nth channel may sample and latch data DATA_R of the nth channel, which is supplied through the data buffer  672 , in response to the sampling signal supplied from the stage STn of the nth channel. The first latch LA 1   n  of each channel may include k bit first latches for respectively latching k bits of each sub-pixel. 
     Second latches LA 2 ( n −1) and LA 2   n  of the (n−1)th and nth channels of the second latch part  680  may simultaneously receive and latch data signals from the first latches LA 1 ( n −1) and LA 1   n  of the (n−1)th and nth channels in response to a load signal LOAD, which is a second latch enable signal, and simultaneously output the latched data signals. The second latch LA 2   n  of each channel may include k bit second latches for respectively latching k bits of each sub-pixel. 
     Referring to  FIG.  9   , a clock CLK input to the shift register  660  and data DATA input to the first latch part  670 , which are input as original signals, are supplied such that a pull-down timing T pdcLK  of the clock CLK is synchronized with a pull-down timing T pdDATA  of each of pieces of data D(n−1), D(n), D(n+1), and D(n+2). 
     As the B data path is longer in the channel area  650 , in a clock CLK_L input to the shift register  660  of the corresponding channel and data DATA_L input to the first latch part  670 , a skew (Tskew=T pdcLK −T pdDATA ), in which the pull-down timing T pdcLK  of the clock CLK mismatches the pull-down timing T pdDATA  of each of the pieces of data D(n−1), D(n), D(n+1), and D(n+2), may occur. 
     However, by using the clock buffer  662  and the data buffer part  672  of the BDB part according to one embodiment, the data buffer part  672  may buffer and latch the input data DATA_L of the corresponding channel, and supply latched data DATA_R of the corresponding channel to the corresponding channel of the first latch part  670  so as to be synchronized with the output clock CLK_R of the clock buffer  662 . Accordingly, the clock buffer  662  and the data buffer part  672  of the BDB part may offset timing mismatch by correcting the skew due to a variation between the pull-down timing T pdCLK  of the clock CLK and the pull-down timing T pdDATA  of each of the pieces of data D(n−1), D(n), D(n+1), and D(n+2). 
     As described above, in the data driver IC  600  according to one embodiment, the BDB may serve as a bi-directional buffer and simultaneously as a latch to offset the skew between the clock and the data, which may occur due to high-frequency driving of the B data path passing through the logic controllers  640 A and  640 B and the channel area  650 , that is, timing mismatching. 
     In addition, in the data driver IC  600  according to one embodiment, since the BDB part serves as a bi-directional buffer, an optimal arrangement for shortening the A data path with the highest driving frequency, that is, adjacent arrangement ( FIG.  4   ) of the receivers  630 A and  630 B and the logic controllers  640 A and  640 B may be realized, thereby overcoming the frequency limitation. 
     Furthermore, the data driver IC  600  according to one embodiment may sequentially enable and activate the channels of the shift register and the first latch part and the BDB part in units of channel blocks using an output of the BDB part, and when all the channels are enabled and activated, the data driver IC  600  may disable and inactivate the channels, thereby reducing power consumption and reducing electromagnetic interference (EMI). A detailed description thereof will be made below. 
       FIG.  10    is a diagram illustrating a principle of reducing power consumption of the data driver IC according to one embodiment. 
     Referring to  FIG.  10   , in the data driver IC  600 , the channel area  650  may be divided into a plurality of channel blocks B 1  to B 7  based on a plurality of BDB parts. 
     For example, during each active period of a horizontal period, pieces of data of a plurality of channels, which are sequentially supplied to the channel area  650  from the first logic controller  640 A, may be sequentially latched for each channel in the first latch part  670  through the B data path in a shift direction (the first direction) of the shift register  660 . 
     First, first latches of a first channel block B 1  may sequentially latch data of the first channel block B 1  for each channel in response to a sampling signal sequentially output from the shift register of the first channel block B 1  as the first channel block B 1  becomes an active state. At this point, a shift register and first latches of each of second to seventh channel blocks B 2  to B 7  are in a non-active state. 
     When the BDB part between the first and second channel blocks B 1  and B 2  is activated to output a clock and data of the corresponding channel, the second channel block B 2  is additionally activated following the first channel block B 1 , and the first latches of the second channel block B 2  may sequentially latch the data of the second channel block B 2  for each channel in response to the sampling signal sequentially output from the shift register of the second channel block B 2 . At this point, the shift register and the first latches of each of the third to seventh channel blocks B 3  to B 7  after the second channel block B 2  maintain a non-active state. 
     When the BDB part between the second and third channel blocks B 2  and B 3  is activated to output a clock and data, the third channel block B 3  is additionally activated following the first and second channel blocks B 1  and B 2 , and the first latches of the third channel block B 3  may sequentially latch the data of the third channel block B 3  for each channel in response to the sampling signal sequentially output from the shift register of the third channel block B 3 . At this time, the shift register and the first latches of each of the fourth to seventh channel blocks B 4  to B 7  after the third channel block B 3  maintain a non-active state. 
     When the BDB part between the third and fourth channel blocks B 3  and B 4  is activated to output a clock and data, the fourth channel block B 4  is additionally activated following the first to third channel blocks B 1  to B 3 , and the first latches of the fourth channel block B 4  may sequentially latch the data of the fourth channel block B 4  for each channel in response to the sampling signal sequentially output from the shift register of the fourth channel block B 4 . At this point, the shift register and the first latches of each of the fifth to seventh channel blocks B 5  to B 7  are in a non-active state. 
     When the BDB part between the fourth and fifth channel blocks B 4  and B 5  is activated to output a clock and data, the fifth channel block B 5  is additionally activated following the first to fourth channel blocks B 1  to B 4 , and the first latches of the fifth channel block B 5  may sequentially latch the data of the fifth channel block B 5  for each channel in response to the sampling signal sequentially output from the shift register of the fifth channel block B 5 . At this point, the shift register and the first latches of each of the sixth to seventh channel blocks B 6  to B 7  are in a non-active state. 
     When the BDB part between the fifth and sixth channel blocks B 5  and B 6  is activated to output a clock and data, the sixth channel block B 6  is additionally activated following the first to fifth channel blocks B 1  to B 5 , and the first latches of the sixth channel block B 6  may sequentially latch the data of the sixth channel block B 6  for each channel in response to the sampling signal sequentially output from the shift register of the sixth channel block B 6 . At this point, the shift register and the first latches of the seventh channel block B 7  are in a non-active state. 
     When the BDB part between the sixth to seventh channel blocks B 6  to B 7  is activated to output a clock and data, all of the first to seventh channel blocks B 1  to B 7  are activated, and the first latches of the seventh channel block B 7  may sequentially latch the data of the seventh channel block B 7  for each channel in response to the sampling signal sequentially output from the shift register of the seventh channel block B 7 . 
     As described above, the first latch part of each of the first to seventh channel blocks B 1  to B 7  may sequentially latch the data of the corresponding channel and output all pieces of the latched data to the second latch part, and then all the BDB parts are inactivated in response to the load signal of the second latch part, and both the shift register and the first latch part of each of the first to seventh channel blocks B 1  to B 7  are inactivated. 
     As described above, the B data path supplied to the channel area  650  from the logic controllers  640 A and  640 B of the data driver IC according to one embodiment is sequentially activated in units of channel blocks in response to the control of the plurality of BDB parts, and maintains a non-active state before the corresponding channel block is activated, thereby reducing power consumption and EMI. 
       FIG.  11    is a block diagram illustrating a partial configuration of a shift register and a latch part of a data driver IC according to one embodiment, and  FIG.  12    is a timing diagram illustrating input/output signals of a BDB part in a non-active state and an active state in the data driver IC according to one embodiment. 
     A BDB part illustrated in  FIG.  11    is different from the BDB part illustrated in  FIG.  8    in that a clock buffer  662  further receives a carry signal SHR of a previous stage STn−1 and a load signal LOAD of a second latch part  680  to control a data buffer part  672 , and thus these differences will be mainly described, and descriptions of components overlapping those of  FIG.  8    will be omitted or simply described. 
     Referring to  FIGS.  11  and  12   , the clock buffer  662  may be enabled in response to the carry signal SHR of the previous stage STn−1, and may buffer the input clock CLK_L supplied from the previous stage STn−1, and then output the buffered output clock CLK_R to a next stage STn. The clock buffer  662  may be disabled in response to the load signal LOAD of the second latch part  680 , which is generated after the first latch part  670  outputs all pieces of the latched data to the second latch part  680 , and then wait for a next enable state. 
     The clock buffer  662  may generate a data enable signal D_EN by phase-inverting the output clock CLK_R and output the generated data enable signal D_EN to the data buffer part  672 . 
     The data buffer part  672  may be enabled and activated, or disabled and inactivated according to the data enable signal D_EN received from the clock buffer  662 . When the data enable signal D_EN is enabled in response to the carry signal SHR of the previous stage STn−1, the data buffer part  672  may be activated to buffer and latch data of an nth channel, which is supplied through a data bus passing through a first latch part LA 1 ( n −1) of an (n−1)th channel, and output the latched data to a first latch LA 1   n  of the nth channel. When the data enable signal D_EN is disabled in response to the load signal LOAD of the second latch part  680 , the data buffer part  672  may be inactivated. 
       FIG.  13    is an equivalent circuit diagram illustrating an internal configuration of the clock buffer and the data buffer of the BDB part according to one embodiment. 
     Referring to  FIG.  13   , the BDB part according to one embodiment includes the clock buffer  662  and the data buffer  672 . 
     The clock buffer  662  may include an input switch part  710 A including first and second switches SW 1 A and SW 2 A, an output switch part  730 A including third and fourth switches SW 3 A and SW 4 A, a buffer part  720 A including a first inverter INV 1 A and a NAND gate circuit NG that are connected between a first connection node N 1 A of the input switch part  710 A and second connection node N 2 A of the output switch part  730 A. The clock buffer  662  further includes a SR latch circuit SR that receives the carry signal SHR supplied from the previous stage STn−1 (see  FIG.  11   ) of the shift register and the load signal LOAD supplied to the second latch part  680  ( FIG.  11   ) respectively as a set signal S and a reset signal R, and a second inverter INV 2 A that inverts an output of the NAND gate circuit NG, which is supplied to the second node N 2 A of the output switch part  730 A, to generate a data enable signal D_EN and supplies the data enable signal D_EN to an input switch part  7106  of the data buffer  672 . 
     In the clock buffer  662 , the first and second switches SW 1 A and SW 2 A of the input switch part  710 A may be connected in series between first and second supply lines IO_L and IO_R, and may determine an input direction in response to the control of the logic controllers  640 A and  640 B ( 640 ). 
     The third and fourth switches SW 3 A and SW 4 A of the output switch part  730 A in the clock buffer  662  are connected in series between the first and second supply lines IO_L and IO_R, and may determine an output direction in response to the control of the logic controllers  640 A and  640 B ( 640 ). 
     The clock buffer  662  may perform a clock buffering operation in a first direction when the first and fourth switches SW 1 A and SW 4 A are turned-on, or may perform a clock buffering operation in a second direction opposite to the first direction when the second and third switches SW 2 A and SW 3 A are turned-on. 
     In the clock buffer  662 , the SR latch circuit SR may receive the carry signal SHR supplied from the previous stage STn−1 ( FIG.  11   ) of the shift register as the set signal S and receive the load signal LOAD supplied to the second latch part  680  ( FIG.  11   ) as the reset signal R, output an enable signal to the NAND gate circuit NG through an output terminal Q in response to the set signal S, and output a disable signal to the NAND gate circuit NG through the output terminal Q in response to the reset signal R. 
     In the clock buffer  662 , the first inverter INV 1 A and the NAND gate circuit NG of the buffer part  720  may be connected in series between the first connection node N 1 A between the first and second switches SW 1 A and SW 2 A, and the second connection node N 2 A between the third and fourth switches SW 3 A and SW 4 A, and may buffer and output the input clock CLK_L or disable the output clock CLK_R. 
     In the clock buffer  662 , when the SR latch circuit SR supplies the enable signal in response to the carry signal SHR supplied from the previous stage STn−1 ( FIG.  11   ), the NAND gate circuit NG may buffer the input clock CLK_L together with the first inverter INV 1 A to supply the output clock CLK_R through the second connection node N 2 A. At this point, the second inverter INV 2 A may phase-invert the output clock CLK_R supplied through the second connection node N 2 A, and output the data enable signal D_EN, which alternates between an enable state and a disabled state in synchronization with the output clock CLK_R, to the input switch part  710 B of the data buffer  672 . 
     When the SR latch circuit SR supplies the disabled signal in response to the load signal LOAD of the second latch part  680  ( FIG.  11   ), the NAND gate circuit NG may disable the output clock CLK_R. In this case, the second inverter INV 2 A may output the data enable signal D_EN in a disabled state supplied through the second connection node N 2 A to the input switch part  710 B of the data buffer  672 . 
     The data buffer  672  may include the input switch part  710 B including first and second switches SW 1 B and SW 2 B, an output switch part  730 B including third and fourth switches SW 3 B and SW 4 B, and a buffer part  720 B including first and second inverters INV 1 B and INV 2 B between the input switch part  710 B and the output switch part  730 B. 
     In the data buffer  672 , the first and second switches SW 1 B and SW 2 B of the input switch part  710 B may be connected in series between first and second supply lines IO_L and IO_R, and may determine an input direction or determine a latch operation in response to the data enable signal D_EN supplied from the clock buffer  662 . The first switch SW 1 B is controlled by the data enable signal D_EN, which is the output of the second inverter INV 2 A of the clock buffer  662 , and the second switch SW 2 B may be controlled by the input signal of the second inverter INV 2 A supplied from the second connection node N 2 A of the clock buffer  662 . 
     In the data buffer  672 , the third and fourth switches SW 3 B and SW 4 B of the output switch part  730 B may be connected in series between the first and second supply lines IO_L and IO_R, and may determine an output direction or the latch operation in response to the control of the logic controllers  640 A and  640 B ( 640 ). 
     In the data buffer  672 , the first and second inverters INV 1 B and INV 2 B of the buffer part  720 B may be connected in series between the first connection node N 1 B between the first and second switches SW 1 B and SW 2 B, and the second connection node N 2 B between the third and fourth switches SW 3 B and SW 4 B, and may buffer and output the input data DATA_L. 
     In the data buffer  672 , when the first and fourth switches SW 1 B and SW 4 B are turned-on and then the second and fourth switches SW 2 B and SW 4 B are turned-on, the input data supplied through the left first supply line IO_L may be buffered through a first path passing through the first switch SW 1 B, the inverters INV 1 B and INV 2 B, and the fourth switch SW 4 B in a first direction, and then latched through a third path passing through the second switch SW 2 B, the inverters INV 1 B and INV 2 B, and the fourth switch SW 4 B, and output through the right second supply line IO_R. 
     In the data buffer  672 , when the second and third switches SW 2 B and SW 3 B are turned-on and then the first and third switches SW 1 B and SW 3 B are turned-on, the input data supplied through the right second supply line IO_R may be buffered through a second path passing through the second switch SW 2 B, the inverters INV 1 B and INV 2 B, and the third switch SW 3 B in a second direction, and then latched through a fourth path passing through the first switch SW 1 B, the inverters INV 1 B and INV 2 B, and the third switch SW 3 B, and output through the left first supply line IO_L. 
     As described above, in the data driver IC  600  according to one embodiment, the BDB part may serve as the bi-directional buffer and simultaneously as the latch to offset a skew between the clock and the data, which may occur due to high-frequency driving of the B data path passing through the logic controllers  640 A and  640 B and the channel area  650 , that is, timing mismatching. 
     In addition, in the data driver IC  600  according to one embodiment, since the BDB part serves as the bi-directional buffer, an optimal arrangement for shortening the A data path with the highest driving frequency, that is, adjacent arrangement of the receivers  630 A and  630 B and the logic controllers  640 A and  640 B may be realized, thereby overcoming the frequency limitation. 
     Furthermore, the data driver IC  600  according to one embodiment may reduce power consumption and EMI by partially enabling and activating, or disabling and inactivating the channels of the first latch part using the output of the BDB part. 
     As described above, the data driver circuit according to one embodiment may prevent timing mismatching between the clock and the data even when the frequency and the number of channels are increased by correcting the skew between the clock and the data using the clock buffer and the data buffer of the BDB part disposed between adjacent channel blocks for each of the plurality of channel blocks, thereby overcoming a frequency limit and securing a degree of freedom to overcome a design limit. 
     The data driver circuit according to one embodiment may be configured as a minimum circuit by using the clock buffer and the data buffer of the BDB part disposed between adjacent channel blocks, so that there is no burden on an increase in a chip area, and current consumption may be reduced and EMI may be minimized by activating the channels only when necessary. 
     The data driver circuit and the display device including the same according to the embodiment may be applied to various electronic devices. For example, the data driver circuit and the display device including the same according to the embodiment may be applied to a mobile device, a video phone, a smart watch, a watch phone, a wearable device, a foldable device, a rollable device, a bendable device, a flexible device, a curved device, an electronic notebook, an e-book, a portable multimedia player (PMP), a personal digital assistant (PDA), an MPEG audio layer-3 player, a mobile medical device, a desktop personal computer (PC), a laptop PC, a netbook computer, a workstation, a navigation device, a vehicle navigation device, a vehicle display device, a television, a wallpaper display device, a signage device, a game device, a notebook computer, a monitor, a camera, a camcorder, a home appliance, and the like. 
     Features, structures, effects, etc. described above in various examples of the present disclosure are included in at least one example of the present disclosure and are not necessarily limited to only one example. Furthermore, features, structures, effects, etc. illustrated in at least one example of the present disclosure may be combined or modified for other examples by those skilled in the art to which the technical idea of the present disclosure pertains. Therefore, the contents related to such combinations and modifications should be interpreted as being included in the technical spirit or scope of the present disclosure. 
     While the present disclosure described above is not limited to the above-described embodiments and the accompanying drawings, it will be apparent to those skilled in the art to which the present disclosure belongs that various substitutions, modifications, and changes may be made herein without departing from the scope of the present disclosure. Therefore, the scope of the present disclosure is defined by the appended claims, and all changes or modifications derived from the meaning, scope, and equivalence of the claims are to be construed as being included in the scope of the present disclosure.