PIXEL SWITCHING AND DISPLAY DEVICE SO THAT

Description

[TECHNICAL FIELD]

[0001] Embodiments of the present inventive concept relate to a pixel circuit and a display apparatus including the pixel circuit. More particularly, embodiments of the present inventive concept relate to a pixel circuit enhancing a reliability and reducing a power consumption due to a decrease of a driving voltage and a display apparatus including the pixel circuit.[BACKGROUND]

[0002] Generally, a display apparatus includes a display panel and a display panel driver. The display panel includes a plurality of gate lines, a plurality of data lines, a plurality of emission lines and a plurality of pixels. The display panel driver includes a gate driver, a data driver, an emission driver and a driving controller. The gate driver outputs gate signals to the gate lines. The data driver outputs data voltages to the data lines. The emission driver outputs emission signals to the emission lines. The driving controller controls the gate driver, the data driver and the emission driver.

[0003] For high luminance driving, an absolute value of a power voltage, an absolute value of an initialization voltage and an absolute value of a gate low level voltage may need to increase. Due to the increase of the absolute value of the power voltage, the absolute value of the initialization voltage and the absolute value of the gate low level voltage, the power consumption of the display apparatus may increase and reliabilities of a switching element of a driving circuit and a switching element of a pixel may be reduced.[DETAILED EXPLANATION OF THE INVENTION][TECHNICAL PURPOSE]

[0004] Embodiments of the present inventive concept provide a pixel circuit capable of enhancing a reliability and reducing a power consumption due to a decrease of a driving voltage.

[0005] Embodiments of the present inventive concept also provide a display apparatus including the pixel circuit. signal is supplied. The fourth transistor is coupled between an anode electrode of the organic light-emitting diode and a data line, and is turned on when the scan signal is supplied. The storage capacitor is coupled between the first node and the anode electrode of the organic light-emitting diode.

[0006] United States Patent Application Publication US2018 / 069069A1 relates to an organic light emitting diode display including a substrate, a plurality of pixels disposed on the substrate, and a plurality of transmitting windows configured to transmit light therethrough. The plurality of transmitting windows is spaced apart from the plurality of pixels. Each of the plurality of pixels includes a transistor and a capacitor. The transistor includes a light-blocking electrode disposed on the substrate and a plurality of electrode members disposed at different layers on the light-blocking electrode. The capacitor includes a first capacitor electrode disposed on a same layer as the light-blocking electrode, and a second capacitor electrode disposed on a same layer as a first one of the plurality of electrode members to overlap the first capacitor electrode.

[0007] United States Patent Application Publication US2015 / 287362A1 relates to a pixel and an organic light-emitting diode (OLED) display having the same. In one aspect, a pixel includes an OLED including an anode and a cathode and configured to emit light corresponding to data signals applied during first and second frame periods. Each of the first and second frame periods includes a first discharge period and a light-emitting period subsequent to the first discharge period. The pixel also includes a pixel circuit configured to control light emission of the OLED, apply a first voltage to the anode during the light-emitting period, apply a second voltage to the cathode, the second voltage having a voltage level less than that of the first voltage, and apply a third voltage to the anode so as to discharge the anode during the first discharge period. The second voltage has different voltage levels during the first and second frame periods.

[0008] United States Patent Application Publication US2011 / 273419A1 relates to a pixel circuit of a flat panel display device and a method for driving thereof. The pixel circuit includes a first transistor having a first gate electrode coupled to a scan line, a second electrode coupled to a data line, a second gate electrode coupled to a controlling signal line, and a first electrode, a second transistor having a first gate electrode coupled to the first electrode of the first transistor, a second electrode coupled to a first voltage source, a second gate electrode coupled to the controlling signal line, and a first electrode, a capacitor coupled between the first gate electrode of the second transistor and the first electrode of the second transistor, and an organic light emitting diode coupled between the first electrode of the second transistor and a second voltage source, in which the threshold voltage of the first and second transistors may be controlled to the required level by supplying a controlling signal of a fixed voltage level to the second gate electrodes of the first and second transistors through the controlling signal line.

[0009] United States Patent Application Publication US2018 / 166519A1 relates to an organic light emitting display device is capable of substantially preventing the occurrence of color mixture and improve the color purity, the organic light emitting display device including: a substrate; a first electrode on the substrate; a pixel defining layer defining a first opening which exposes at least a portion of the first electrode; a first organic light emission layer on the first electrode; and a second electrode on the first organic light emission layer, wherein the pixel defining layer may include quantum dots.[DETAILED EXPLANATION OF THE INVENTION][TECHNICAL PURPOSE]

[0010] Embodiments of the present inventive concept provide a pixel circuit capable of enhancing a reliability and reducing a power consumption due to a decrease of a driving voltage.

[0011] Embodiments of the present inventive concept also provide a display apparatus including the pixel circuit.TECHNICAL SOLUTION]

[0012] The invention is set out in the appended set of claims.[EFFECT OF THE INVENTION]

[0013] According to the pixel circuit and the display apparatus including the pixel circuit, the signal different from the signal applied to the control electrode of the organic light emitting element initialization switching element is applied to the conductive layer facing the control electrode of the organic light emitting element initialization switching element so that the threshold voltage of the organic light emitting element initialization switching element may be decreased.

[0014] The threshold voltage of the organic light emitting element initialization switching element is decreased so that the driving voltage of the display apparatus may be decreased. Thus, a power consumption of the display apparatus may be reduced.

[0015] In addition, the threshold voltage of the organic light emitting element initialization switching element is decreased so that the reliability of the switching element of the driving circuit of the display apparatus and the reliability of the switching element of the pixel may be enhanced.[BRIEF EXPLANATION OF THE DRAWINGS]

[0016] FIG. 1 is a block diagram illustrating a display apparatus according to an embodiment of the present inventive concept. FIG. 2 is a circuit diagram illustrating a pixel of a display panel of FIG. 1. FIG. 3 is a timing diagram illustrating input signals applied to the pixel of FIG. 2. FIG. 4 is a cross-sectional view illustrating a portion of an organic light emitting element initialization switching element of FIG. 2. FIG. 5 is a graph illustrating a shift of a threshold voltage of the organic light emitting element initialization switching element of FIG. 2. FIG. 6A is a cross-sectional view illustrating an organic light emitting element of FIG. 2. FIG. 6B is a cross-sectional view illustrating an organic light emitting element of FIG. 2. FIG. 7 is a table illustrating voltages at nodes of an organic light emitting element and an organic light emitting element initialization switching element according to a comparative embodiment. FIG. 8 is a table illustrating voltages at nodes of the organic light emitting element and the organic light emitting element initialization switching element of FIG. 2. FIG. 9 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept. FIG. 10 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept. FIG. 11 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept. FIG. 12 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept. [BEST MODE FOR CARRYING OUT THE INVENTION]

[0017] Hereinafter, the present inventive concept will be explained in detail with reference to the accompanying drawings.

[0018] FIG. 1 is a block diagram illustrating a display apparatus according to an embodiment of the present inventive concept.

[0019] Referring to FIG. 1, the display apparatus includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500 and an emission driver 600.

[0020] The display panel 100 has a display region on which an image is displayed and a peripheral region adjacent to the display region.

[0021] The display panel 100 includes a plurality of gate lines GWL, GIL and GBL, a plurality of data lines DL, a plurality of emission lines EL and a plurality of pixels electrically connected to the gate lines GWL, GIL and GBL, the data lines DL and the emission lines EL. The gate lines GWL, GIL and GBL extend in a first direction D1, the data lines DL extend in a second direction D2 crossing the first direction D1 and the emission lines EL extend in the first direction D1.

[0022] The driving controller 200 receives input image data IMG and an input control signal CONT from an external apparatus (not shown). For example, the input image data IMG may include red image data, green image data and blue image data. The input image data IMG may include white image data. The input image data IMG may include magenta image data, cyan image data and yellow image data. The input control signal CONT may include a master clock signal and a data enable signal. The input control signal CONT may further include a vertical synchronizing signal and a horizontal synchronizing signal.

[0023] The driving controller 200 generates a first control signal CONT1, a second control signal CONT2, a third control signal CONT3, a fourth control signal CONT4 and a data signal DATA based on the input image data IMG and the input control signal CONT.

[0024] The driving controller 200 generates the first control signal CONT1 for controlling an operation of the gate driver 300 based on the input control signal CONT, and outputs the first control signal CONT1 to the gate driver 300. The first control signal CONT1 may include a vertical start signal and a gate clock signal.

[0025] The driving controller 200 generates the second control signal CONT2 for controlling an operation of the data driver 500 based on the input control signal CONT, and outputs the second control signal CONT2 to the data driver 500. The second control signal CONT2 may include a horizontal start signal and a load signal.

[0026] The driving controller 200 generates the data signal DATA based on the input image data IMG. The driving controller 200 outputs the data signal DATA to the data driver 500.

[0027] The driving controller 200 generates the third control signal CONT3 for controlling an operation of the gamma reference voltage generator 400 based on the input control signal CONT, and outputs the third control signal CONT3 to the gamma reference voltage generator 400.

[0028] The driving controller 200 generates the fourth control signal CONT4 for controlling an operation of the emission driver 600 based on the input control signal CONT, and outputs the fourth control signal CONT4 to the emission driver 600.

[0029] The gate driver 300 generates gate signals driving the gate lines GWL, GIL and GBL in response to the first control signal CONT1 received from the driving controller 200. The gate driver 300 may sequentially output the gate signals to the gate lines GWL, GIL and GBL.

[0030] The gamma reference voltage generator 400 generates a gamma reference voltage VGREF in response to the third control signal CONT3 received from the driving controller 200. The gamma reference voltage generator 400 provides the gamma reference voltage VGREF to the data driver 500. The gamma reference voltage VGREF has a value corresponding to a level of the data signal DATA.

[0031] In an embodiment, the gamma reference voltage generator 400 may be disposed in the driving controller 200, or in the data driver 500.

[0032] The data driver 500 receives the second control signal CONT2 and the data signal DATA from the driving controller 200, and receives the gamma reference voltages VGREF from the gamma reference voltage generator 400. The data driver 500 converts the data signal DATA into data voltages having an analog type using the gamma reference voltages VGREF. The data driver 500 outputs the data voltages to the data lines DL.

[0033] For example, the data driver 500 may be integratedly formed with the driving controller 200 so that the data driver 500 and the driving controller 200 may form a timing controller embedded data driver TED.

[0034] The emission driver 600 generates emission signals to drive the emission lines EL in response to the fourth control signal CONT4 received from the driving controller 200. The emission driver 600 outputs the emission signals to the emission lines EL.

[0035] FIG. 2 is a circuit diagram illustrating a pixel of the display panel 100 of FIG. 1. FIG. 3 is a timing diagram illustrating input signals applied to the pixel of FIG. 2.

[0036] Referring to FIGS. 1 to 3, the display panel 100 includes the plurality of the pixels. Each pixel includes an organic light emitting element OLED.

[0037] The pixels receive a data write gate signal GW, a data initialization gate signal GI, an organic light emitting elementinitialization gate signal GB, the data voltage VDATA and the emission signal EM and the organic light emitting elements OLED of the pixels emit light corresponding to the level of the data voltage VDATA to display the image.

[0038] At least one of the pixels includes a driving switching element T1, a data initializer T4-1 and T4-2, a data writer T2, T3-1 and T3-2, an organic light emitting element OLED, an organic light emitting element initializer T7-1 and T7-2 and a light emitting controller T5 and T6. The pixel may further include a storage capacitor CST and a stabilization capacitor CL.

[0039] The data initializer T4-1 and T4-2 initializes a voltage at a control electrode N1 of the driving switching element T1 to a first initialization voltage VINT1.

[0040] The data initializer T4-1 and T4-2 includes a control electrode receiving the data initialization gate signal GI, an input electrode receiving the first initialization voltage VINT1 and an output electrode connected to the control electrode N1 of the driving switching element T1.

[0041] For example, the data initializer T4-1 and T4-2 may include a (4-1)-th switching element T4-1 and a (4-2)-th switching element T4-2 which are connected to each other in series. The (4-1)-th switching element T4-1 may include a control electrode receiving the data initialization gate signal GI, an input electrode connected to an output electrode N5 of the (4-2)-th switching element T4-2 and an output electrode connected to the control electrode N1 of the driving switching element T1. The (4-2)-th switching element may include a control electrode receiving the data initialization gate signal GI, an input electrode receiving the first initialization voltage VINT1 and the output electrode connected to the input electrode of the (4-1)-th switching element T4-1.

[0042] When the data initializer T4-1 and T4-2 includes the (4-1)-th switching element T4-1 and the (4-2)-th switching element T4-2 which are connected to each other in series, a current leakage due to a high voltage applied to both ends of the data initializer T4-1 and T4-2 may be prevented.

[0043] The data writer T2, T3-1 and T3-2 may write a data voltage to the control electrode N1 of the driving switching element T1 based on a data write gate signal GW.

[0044] The data writer T2, T3-1 and T3-2 may include a first data writer T2 including a control electrode receiving the data write gate signal GW, an input electrode receiving the data voltage VDATA and an output electrode connected to an input electrode N2 of the driving switching element T1.

[0045] In addition, the data writer T2, T3-1 and T3-2 may further include a second data writer T3-1 and T3-2 including a control electrode receiving the data write gate signal GW, an input electrode connected to an output electrode N3 of the driving switching element T1 and an output electrode connected to the control electrode N1 of the driving switching element T1.

[0046] For example, the second data writer T3-1 and T3-2 may include a (3-1)-th switching element T3-1 and a (3-2)-th switching element T3-2 which are connected to each other in series. The (3-1)-th switching element T3-1 may include a control electrode receiving the data write gate signal GW, an input electrode connected to an output electrode N4 of the (3-2)-th switching element T3-2 and an output electrode connected to the control electrode N1 of the driving switching element T1. The (3-2)-th switching element may include a control electrode receiving the data write gate signal GW, an input electrode connected to the output electrode N3 of the driving switching element T1 and the output electrode connected to the input electrode of the (3-1)-th switching element T3-1.

[0047] When the second data writer T3-1 and T3-2 includes the (3-1)-th switching element T3-1 and the (3-2)-th switching element T3-2 which are connected to each other in series, a current leakage due to a high voltage applied to both ends of the second data writer T3-1 and T3-2 may be prevented.

[0048] The organic light emitting element initializer T7-1 and T7-2 initializes an anode electrode of the organic light emitting element to a second initialization voltage VINT2 based on the organic light emitting element initialization gate signal GB.

[0049] For example, an absolute value of the second initialization voltage VINT2 may be greater than an absolute value of the first initialization voltage VINT1. For high luminance driving, an absolute value of a second power voltage ELVSS, the absolute value of the initialization voltage and an absolute value of a low level VGL of the gate signal increase, a drain-source voltage VDS of the (3-1)-th switching element T3-1, the (3-2)-th switching element T3-2, the (4-1)-th switching element T4-1 and the (4-2)-th switching element T4-2 may increase so that the leakage may occur. Thus, the first initialization voltage VINT1 and the second initialization voltage VINT2 may be set differently.

[0050] The organic light emitting element initializer T7-1 and T7-2 may include a (7-1)-th switching element T7-1 and a (7-2)-th switching element T7-2 which are connected to each other in series. The (7-1)-th switching element T7-1 may include a control electrode receiving the organic light emitting element initialization gate signal GB, an input electrode connected to an output electrode of the (7-2)-th switching element T7-2 and an output electrode connected to the anode electrode of the organic light emitting element OLED. The (7-2)-th switching element may include a control electrode receiving the organic light emitting element initialization gate signal GB, an input electrode receiving the second initialization voltage VINT2 and the output electrode connected to the input electrode of the (7-1)-th switching element T7-1.

[0051] The light emitting controller T5 and T6 controls a light emission of the organic light emitting element OLED based on the emission signal EM.

[0052] The light emitting controller T5 and T6 may include a first light emitting controller T5 including a control electrode receiving the emission signal EM, an input electrode receiving a first power voltage ELVDD and an output electrode connected to the input electrode N2 of the driving switching element T1.

[0053] The light emitting controller T5 and T6 may further include a second light emitting controller T6 including a control electrode receiving the emission signal EM, an input electrode connected to the output electrode N3 of the driving switching element T1 and an output electrode connected to the anode electrode of the organic light emitting element OLED.

[0054] The storage capacitor CST includes a first electrode receiving the first power voltage ELVDD and a second electrode connected to the control electrode N1 of the driving switching element T1.

[0055] The stabilization capacitor CL includes a first electrode receiving the first power voltage ELVDD and a second electrode connected to the input electrode of the (3-1)-th switching element T3-1. The voltage at the input electrode of the (3-1)-th switching element T3-1 is stabilized by the stabilization capacitor CL so that the current leakage through the (3-1)-th switching element T3-1 and the (3-2)-th switching element T3-2 may be reduced.

[0056] The second electrode of the stabilization capacitor CL may be also connected to the input electrode of the (4-1)-th switching element T4-1. The voltage at the input electrode of the (4-1)-th switching element T4-1 is stabilized by the stabilization capacitor CL so that the current leakage through the (4-1)-th switching element T4-1 and the (4-2)-th switching element T4-2 may be reduced.

[0057] The organic light emitting element OLED includes the anode electrode and a cathode electrode receiving the second power voltage ELVSS.

[0058] In FIG. 3, during a first duration DU1, the first node N1 and the storage capacitor CST are initialized in response to the data initialization gate signal GI. During a second duration DU2, a threshold voltage |VTH| of the first switching element T1 is compensated and the data voltage VDATA of which the threshold voltage |VTH| is compensated is written to the first node N1 in response to the data write gate signal GW. During a third duration DU3, the anode electrode of the organic light emitting element OLED is initialized in response to the organic light emitting element initialization gate signal GB. During a fourth duration DU4, the organic light emitting element OLED emit the light in response to the emission signal EM so that the pixel displays the image.

[0059] Although the off duration of the emission signal EM corresponds to first to third durations DU1, DU2 and DU3 in the present embodiment, the present inventive concept may not be limited thereto. The off duration of the emission signal EM may include the data write duration DU2 and the off duration of the emission signal EM may be longer than the first to third durations DU1, DU2 and DU3.

[0060] During the first duration DU1, the data initialization gate signal GI may have an active level. For example, the active level of the data initialization gate signal GI may be a low level. When the data initialization gate signal GI has the active level, the (4-1)-th switching element T4-1 and the (4-2)-th switching element T4-2 are turned on so that the first initialization voltage VINT1 may be applied to the first node N1.

[0061] During the second duration DU2, the data write gate signal GW may have an active level. For example, the active level of the data write gate signal GW may be a low level. When the data write gate signal GW has the active level, a second switching element T2 and the (3-1)-th switching element T3-1 and the (3-2)-th switching element T3-2 are turned on. In addition, the first switching element T1 is turned on in response to the first initialization voltage VINT1.

[0062] A voltage which is subtraction an absolute value |VTH| of the threshold voltage of the first switching element T1 from the data voltage VDATA may be charged at the first node N1 along a path generated by the first, second, (3-1)-th and (3-2)-th switching elements T1, T2, T3-1 and T3-2.

[0063] During the third duration DU3, the organic light emitting element initialization gate signal GB may have an active level. For example, the active level of the organic light emitting element initialization gate signal GB may be a low level. When the organic light emitting element initialization gate signal GB has the active level, the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 are turned on so that the second initialization voltage VINT2 may be applied to the anode electrode of the organic light emitting element OLED.

[0064] During the fourth duration DU4, the emission signal EM may have an active level. The active level of the emission signal EM may be a low level. When the emission signal EM has the active level, the fifth switching element T5 and the sixth switching element T6 are turned on. In addition, the first switching element T1 is turned on by the data voltage VDATA.

[0065] A driving current flows through the fifth switching element T5, the first switching element T1 and the sixth switching element T6 to drive the organic light emitting element OLED. An intensity of the driving current may be determined by the level of the data voltage VDATA. A luminance of the organic light emitting element OLED is determined by the intensity of the driving current.

[0066] The threshold voltage |VTH| is compensated during the second duration DU2, so that the driving current may be determined regardless of the threshold voltage |VTH| of the first switching element T1 when the organic light emitting element OLED emits the light during the fourth duration DU4.

[0067] FIG. 4 is a cross-sectional view illustrating a portion of an organic light emitting element initialization switching element T7-1 and T7-2 of FIG. 2. FIG. 5 is a graph illustrating a shift of a threshold voltage of the organic light emitting element initialization switching element T7-1 and T7-2 of FIG. 2.

[0068] Referring to FIGS. 1 to 5, the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 may include a polyimide layer PI, a barrier layer BR disposed on the polyimide layer PI, a conductive layer ML disposed on the barrier layer BR, a buffer layer BF covering the conductive layer ML, a P+ layer disposed on the buffer layer BR, an active layer AL disposed between the buffer layer BF and the P+ layer, a gate insulation layer GI covering the P+ layer and the active layer AL and a control electrode G disposed on the gate insulation layer GI.

[0069] In the present embodiment, the first to (7-2)-th switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5, T6, T7-1 and T7-2 may include a control electrode G, an input electrode, an output electrode and a conductive layer ML facing the control electrode G.

[0070] The same control signal may be applied to the control electrode G and the conductive layer ML of the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6.

[0071] Unlike the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6, different control signals may be applied to the control electrode G and the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2.

[0072] For example, the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 includes a control electrode G receiving the organic light emitting element initialization gate signal GB, an input electrode receiving the second initialization voltage VINT2, an output electrode connected to the anode electrode of the light organic light emitting element OLED and the conductive layer ML facing the control electrode G and receiving a compensation control signal different from the organic light emitting element initialization gate signal GB.

[0073] In the present embodiment, the compensation control signal may be the first initialization voltage VINT1. For example, the second initialization voltage VINT2 is -14.1V and the first initialization voltage VINT1 is -3.5V. For example, the first initialization voltage VINT1 and the second initialization voltage VINT2 are less than 0 and an absolute value of the first initialization voltage VINT1 may be less than the second initialization voltage VINT2.

[0074] Thus, the compensation control signal VINT1 is applied to the conductive layers ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 so that threshold voltages Vth of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 may be shifted in a positive direction.

[0075] In FIG. 5, C1 represents a current voltage curve of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 when the organic light emitting element initialization gate signal GB is applied to the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2. C2 represents a current voltage curve of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 when the compensation control signal VINT1 is applied to the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2.

[0076] The threshold voltage Vth of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 is shifted in the positive direction so that the driving voltage (e.g. the absolute value of the low level VGL of the gate signal) of the display apparatus may be reduced. Accordingly, the power consumption of the display apparatus may be reduced. In addition, the driving voltage (e.g. the absolute value of the low level VGL of the gate signal) of the display apparatus is reduced so that a reliability of the gate driver 300 may be enhanced.

[0077] FIG. 6A is a cross-sectional view illustrating an organic light emitting element of FIG. 2. FIG. 6B is a cross-sectional view illustrating an organic light emitting element of FIG. 2.

[0078] In FIG. 6A, for example, the organic light emitting element OLED may include a single light emitting layer R, G and B. In FIG. 6B, for example, the organic light emitting element OLED may include two light emitting layers R1, G1, B1, R2, G2 and B2 to enhance a reliability and a lifetime.

[0079] Referring to FIG. 6A, the organic light emitting element OLED may include the anode electrode ANODE, a hole transport layer HTL disposed on the anode electrode ANODE, the light emitting layer R, G and B disposed on the hole transport layer HTL, an electron transport layer ETL disposed on the light emitting layer R, G and B and a cathode electrode CATHODE disposed on the electron transport layer ETL.

[0080] Referring to FIG. 6B, the organic light emitting element OLED may include the anode electrode ANODE, a first light emitting layer R1, G1 and B1 disposed on the anode electrode ANODE, a second light emitting layer R2, G2 and B2 disposed on the first light emitting layer R1, G1 and B1 and a cathode electrode CATHODE disposed on the second light emitting layer R2, G2 and B2.

[0081] For example, the organic light emitting element OLED may further include the anode electrode ANODE, a first hole transport layer HTL1 disposed between the anode electrode ANODE and the first light emitting layer R1, G1 and B1, a first electron transport layer ETL1 disposed on the first light emitting layer R1, G1 and B1, a n-type charge generation layer nCGL disposed on the first electron transport layer ETL1, a p-type charge generation layer pCGL disposed on the n-type charge generation layer nCGL, a second hole transport layer HTL2 disposed between the p-type charge generation layer pCGL and the second light emitting layer R2, G2 and B2 and a second electron transport layer ETL2 disposed between the second light emitting layer R2, G2 and B2 and the cathode electrode CATHODE.

[0082] When the display apparatus includes the organic light emitting element OLED including the first and second light emitting layers R1, G1, B1, R2, G2 and B2, the driving voltage of the display apparatus may be further increased.

[0083] FIG. 7 is a table illustrating voltages at nodes of an organic light emitting element and an organic light emitting element initialization switching element according to a comparative embodiment. FIG. 8 is a table illustrating voltages at nodes of the organic light emitting element and the organic light emitting element initialization switching element of FIG. 2.

[0084] In FIG. 7, for example, the organic light emitting element initialization gate signal GB is applied to the control electrode G and the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2. In FIG. 8, for example, the organic light emitting element initialization gate signal GB is applied to the control electrode G of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 and the compensation control signal VINT1 is applied to the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2. In FIGS. 7 and 8, for example, the second initialization voltage VINT2 and the second power voltage ELVSS may be -14.1V. In FIGS. 7 and 8, a single switching element T7 is illustrated instead of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 for convenience of explanation.

[0085] In FIG. 7, when the low level VGL of the gate signal (e.g. GI, GB and GW) is -13.6V, the anode voltage is -11.7V. Herein, the gate source voltage VGS of a seventh switching element T7 is less than a threshold voltage of the seventh switching element T7 so that the seventh switching element T7 does not normally operate. When the low level VGL of the gate signal (e.g. GI, GB and GW) is -14.6V, the anode voltage is -12.3V. Herein, the gate source voltage VGS of a seventh switching element T7 is less than the threshold voltage of the seventh switching element T7 so that the seventh switching element T7 does not normally operate.

[0086] When the low level VGL of the gate signal (e.g. GI, GB and GW) is -17.6V, the anode voltage is -14.1V. Herein, the gate source voltage VGS of the seventh switching element T7 reaches the threshold voltage of the seventh switching element T7 so that the seventh switching element T7 may normally operate.

[0087] In the case of FIG. 7, the pixel normally operates when the low level VGL of the gate signal (e.g. GI, GB and GW) is equal to or less than -17.6V.

[0088] In FIG. 8, for example, the compensation control signal VINT1 is applied to the conductive layer ML so that the threshold voltage of the seventh switching element T7 may be shifted in the positive direction by 1.5V to 2V as shown in FIG. 5.

[0089] In FIG. 8, when the low level VGL of the gate signal (e.g. GI, GB and GW) is -13.6V, the anode voltage is -12.7V. Herein, the gate source voltage VGS of the seventh switching element T7 is less than a threshold voltage of the seventh switching element T7 so that the seventh switching element T7 does not normally operate. When the low level VGL of the gate signal (e.g. GI, GB and GW) is -14.6V, the anode voltage is -13.6V. Herein, the gate source voltage VGS of a seventh switching element T7 is less than the threshold voltage of the seventh switching element T7 so that the seventh switching element T7 does not normally operate.

[0090] When the low level VGL of the gate signal (e.g. GI, GB and GW) is -15.6V, the anode voltage is -14.1V. Herein, the gate source voltage VGS of the seventh switching element T7 reaches the threshold voltage of the seventh switching element T7 so that the seventh switching element T7 may normally operate.

[0091] In the case of FIG. 8, the pixel normally operates when the low level VGL of the gate signal (e.g. GI, GB and GW) is equal to or less than -15.6V so that the absolute value of the driving voltage VGL may decrease by 2V compared to the case of FIG. 7. When the driving voltage VGL is decreased, the power consumption of the display apparatus may be reduced. In addition, when the driving voltage VGL is decreased, the reliability of the gate driver 300 may be enhanced.

[0092] According to the present embodiment, the signal VINT1 different from the signal GB applied to the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 is applied to the conductive layer ML facing the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 so that the threshold voltage of the organic light emitting element initialization switching element T7-1 and T7-2 may be decreased.

[0093] Thus, the power consumption of the display apparatus may be reduced and the reliability of the gate driver 300 may be enhanced.

[0094] FIG. 9 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept.

[0095] The display apparatus according to the present embodiment is substantially the same as the display apparatus of the previous embodiment explained referring to FIGS. 1 to 8 except for the signal applied to the control electrode of the (7-1)-th switching element and the (7-2)-th switching element. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous embodiment of FIGS. 1 to 8 and any repetitive explanation concerning the above elements will be omitted.

[0096] Referring to FIGS. 1 and 3 to 9, the display apparatus includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500 and an emission driver 600.

[0097] At least one of the pixels may include a driving switching element T1, a data initializer T4-1 and T4-2, a data writer T2, T3-1 and T3-2, an organic light emitting element OLED, an organic light emitting element initializer T7-1 and T7-2 and a light emitting controller T5 and T6. The pixel may further include a storage capacitor CST and a stabilization capacitor CL.

[0098] The organic light emitting element initializer T7-1 and T7-2 initializes an anode electrode of the organic light emitting element to a second initialization voltage VINT2 based on the organic light emitting element initialization gate signal GB.

[0099] In the present embodiment, the first to (7-2)-th switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5, T6, T7-1 and T7-2 may include a control electrode G, an input electrode, an output electrode and a conductive layer ML facing the control electrode G.

[0100] The same control signal may be applied to the control electrode G and the conductive layer ML of the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6.

[0101] Unlike the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6, different control signals may be applied to the control electrode G and the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2.

[0102] In the present embodiment, a compensation control signal VX may be independently formed from other driving signals. The (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 may be p-type switching elements so that the compensation control signal VX may be applied in a positive direction. Alternatively, the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 may be n-type switching elements so that the compensation control signal VX may be applied in a negative direction.

[0103] For example, a shift range of the threshold voltage Vth of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2 may be greater than 0V and less than 10V.

[0104] According to the present embodiment, the signal VX different from the signal GB applied to the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 is applied to the conductive layer ML facing the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 so that the threshold voltage of the organic light emitting element initialization switching element T7-1 and T7-2 may be decreased.

[0105] Thus, the power consumption of the display apparatus may be reduced and the reliability of the gate driver 300 may be enhanced.

[0106] FIG. 10 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept.

[0107] The display apparatus according to the present embodiment is substantially the same as the display apparatus of the previous embodiment explained referring to FIGS. 1 to 8 except for the pixel circuit. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous embodiment of FIGS. 1 to 8 and any repetitive explanation concerning the above elements will be omitted.

[0108] Referring to FIGS. 1, 3 to 8 and 10, the display apparatus includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500 and an emission driver 600.

[0109] At least one of the pixels may include a driving switching element T1, a data initializer T4, a data writer T2 and T3, an organic light emitting element OLED, an organic light emitting element initializer T7 and a light emitting controller T5 and T6. The pixel may further include a storage capacitor CST and a stabilization capacitor CL.

[0110] In the present embodiment, the second data writer T3 may include a single switching element T3 unlike FIG. 2.

[0111] In the present embodiment, the data initializer T4 may include a single switching element T4 unlike FIG. 2.

[0112] In the present embodiment, the organic light emitting element initializer T7 may include a single switching element T7 unlike FIG. 2.

[0113] The organic light emitting element initializer T7 initializes an anode electrode of the organic light emitting element to a second initialization voltage VINT2 based on the organic light emitting element initialization gate signal GB.

[0114] In the present embodiment, the first to seventh switching elements T1 to T7 may include a control electrode G, an input electrode, an output electrode and a conductive layer ML facing the control electrode G.

[0115] The same control signal may be applied to the control electrode G and the conductive layer ML of the first to sixth switching elements T1 to T6.

[0116] Unlike the first to sixth switching elements T1 to T6, different control signals may be applied to the control electrode G and the conductive layer ML of the seventh switching element T7.

[0117] In the present embodiment, the compensation control signal may be the first initialization voltage VINT1. Alternatively, the compensation control signal may be independently generated from other driving signals as explained referring to FIG. 9.

[0118] According to the present embodiment, the signal VINT1 different from the signal GB applied to the control electrode G of the organic light emitting element initialization switching element T7 is applied to the conductive layer ML facing the control electrode G of the organic light emitting element initialization switching element T7 so that the threshold voltage of the organic light emitting element initialization switching element T7 may be decreased.

[0119] Thus, the power consumption of the display apparatus may be reduced and the reliability of the gate driver 300 may be enhanced.

[0120] FIG. 11 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept.

[0121] The display apparatus according to the present embodiment is substantially the same as the display apparatus of the previous embodiment explained referring to FIGS. 1 to 8 except for the signal applied to the control electrode of the (7-1)-th switching element and the (7-2)-th switching element. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous embodiment of FIGS. 1 to 8 and any repetitive explanation concerning the above elements will be omitted.

[0122] Referring to FIGS. 1, 3 to 8 and 11, the display apparatus includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500 and an emission driver 600.

[0123] At least one of the pixels may include a driving switching element T1, a data initializer T4-1 and T4-2, a data writer T2, T3-1 and T3-2, an organic light emitting element OLED, an organic light emitting element initializer T7-1 and T7-2 and a light emitting controller T5 and T6. The pixel may further include a storage capacitor CST and a stabilization capacitor CL.

[0124] The organic light emitting element initializer T7-1 and T7-2 initializes an anode electrode of the organic light emitting element to a second initialization voltage VINT2 based on the organic light emitting element initialization gate signal GB.

[0125] In the present embodiment, the organic light emitting element initialization gate signal GB may have a phase same as a phase of the data write gate signal GW. For example, the data write gate signal GW may be directly applied to the control electrode G of the organic light emitting element initializer T7-1 and T7-2.

[0126] In the present embodiment, the first to (7-2)-th switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5, T6, T7-1 and T7-2 may include a control electrode G, an input electrode, an output electrode and a conductive layer ML facing the control electrode G.

[0127] The same control signal may be applied to the control electrode G and the conductive layer ML of the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6.

[0128] Unlike the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6, different control signals may be applied to the control electrode G and the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2.

[0129] In the present embodiment, the compensation control signal may be the first initialization voltage VINT1. Alternatively, the compensation control signal may be independently generated from other driving signals as explained referring to FIG. 9.

[0130] According to the present embodiment, the signal VINT1 different from the signal GB applied to the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 is applied to the conductive layer ML facing the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 so that the threshold voltage of the organic light emitting element initialization switching element T7-1 and T7-2 may be decreased.

[0131] Thus, the power consumption of the display apparatus may be reduced and the reliability of the gate driver 300 may be enhanced.

[0132] FIG. 12 is a circuit diagram illustrating a pixel of a display panel according to an embodiment of the present inventive concept.

[0133] The display apparatus according to the present embodiment is substantially the same as the display apparatus of the previous embodiment explained referring to FIGS. 1 to 8 except for the signal applied to the control electrode of the (7-1)-th switching element and the (7-2)-th switching element. Thus, the same reference numerals will be used to refer to the same or like parts as those described in the previous embodiment of FIGS. 1 to 8 and any repetitive explanation concerning the above elements will be omitted.

[0134] Referring to FIGS. 1, 3 to 8 and 12, the display apparatus includes a display panel 100 and a display panel driver. The display panel driver includes a driving controller 200, a gate driver 300, a gamma reference voltage generator 400, a data driver 500 and an emission driver 600.

[0135] At least one of the pixels may include a driving switching element T1, a data initializer T4-1 and T4-2, a data writer T2, T3-1 and T3-2, an organic light emitting element OLED, an organic light emitting element initializer T7-1 and T7-2 and a light emitting controller T5 and T6. The pixel may further include a storage capacitor CST and a stabilization capacitor CL.

[0136] The organic light emitting element initializer T7-1 and T7-2 initializes an anode electrode of the organic light emitting element to a second initialization voltage VINT2 based on the organic light emitting element initialization gate signal GB.

[0137] In the present embodiment, the organic light emitting element initialization gate signal GB may have a phase same as a phase of the data initialization gate signal GI. For example, the data initialization gate signal GI may be directly applied to the control electrode G of the organic light emitting element initializer T7-1 and T7-2.

[0138] In the present embodiment, the first to (7-2)-th switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5, T6, T7-1 and T7-2 may include a control electrode G, an input electrode, an output electrode and a conductive layer ML facing the control electrode G.

[0139] The same control signal may be applied to the control electrode G and the conductive layer ML of the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6.

[0140] Unlike the first to sixth switching elements T1, T2, T3-1, T3-2, T4-1, T4-2, T5 and T6, different control signals may be applied to the control electrode G and the conductive layer ML of the (7-1)-th switching element T7-1 and the (7-2)-th switching element T7-2.

[0141] In the present embodiment, the compensation control signal may be the first initialization voltage VINT1. Alternatively, the compensation control signal may be independently generated from other driving signals as explained referring to FIG. 9.

[0142] According to the present embodiment, the signal VINT1 different from the signal GB applied to the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 is applied to the conductive layer ML facing the control electrode G of the organic light emitting element initialization switching element T7-1 and T7-2 so that the threshold voltage of the organic light emitting element initialization switching element T7-1 and T7-2 may be decreased.

[0143] Thus, the power consumption of the display apparatus may be reduced and the reliability of the gate driver 300 may be enhanced.[INDUSTRIAL AVAILABILITY]

[0144] According to the pixel circuit and the display apparatus of the present inventive concept as explained above, the reliability may be enhanced and the power consumption may be reduced due to the decrease of the driving voltage.

Claims

1. A display apparatus comprising: a display panel (100) including a plurality of gate lines (GWL, GIL, GBL), a plurality of data lines (DL), a plurality of emission lines (EL) and a plurality of pixels electrically connected to the gate lines (GWL, GIL, GBL), the data lines (DL) and the emission lines (EL); a gate driver (300) configured to output a data initialization gate signal (GI), a data write gate signal (GW), and an organic light emitting element initialization gate signal (GB) to corresponding gate lines of the plurality of gate lines; a data driver (500) configured to output a data voltage (VDATA) to a data line of the plurality of data lines (DL); and an emission driver (600) configured to output an emission signal (EM) to an emission line of the plurality of emission lines (EL), the display apparatus is configured to supply a first initialization voltage (VINT1) and a second initialization voltage (VINT2) to the plurality of pixels, wherein each pixel of at least one of the pixels comprises a pixel circuit, the pixel circuit comprising: a driving transistor (T1); a data initializer (T4; T4-1, T4-2) comprising a control electrode configured to receive the data initialization gate signal (GI), a first electrode connected to a line providing a first initialization voltage (VINT1) and a second electrode connected to the control electrode of the driving transistor, wherein the data initializer is configured to initialize a voltage of the control electrode of the driving transistor (T1) to the first initialization voltage (VINT1) based on the data initialization gate signal (GI); a data writer (T2, T3-1, T3-2; T2, T3) configured to write the data voltage (VDATA) to the control electrode of the driving transistor (T1) based on the data write gate signal (GW); an organic light emitting element (OLED); an organic light emitting element initializer (T7; T7-1, T7-2) configured to initialize an anode electrode of the organic light emitting element (OLED) to the second initialization voltage (VINT2) based on the organic light emitting element initialization gate signal (GB), wherein the absolute value of the second initialization voltage is greater than the absolute value of the first initialization voltage; and a light emitting controller (T5, T6) configured to control an emission of the organic light emitting element (OLED) based on the emission signal (EM), wherein the organic light emitting element initializer (T7; T7-1, T7-2) comprises a control electrode configured to receive the organic light emitting element initialization gate signal (GB), an input electrode connected to a line providing the second initialization voltage (VINT2), an output electrode connected to the anode electrode of the organic light emitting element (OLED) and a conductive layer (ML) facing the control electrode of the organic light emitting element initializer (T7; T7-1, T7-2), the conductive layer (ML) connected to the line providing the first initialization voltage (VINT1), and wherein the data initializer (T4; T4-1, T4-2), the data writer (T2, T3-1, T3-2; T2, T3), the organic light emitting element initializer (T7; T7-1, T7-2) and the light emitting controller (T5, T6) are all switching elements.

2. The display apparatus of claim 1, wherein the data writer (T2, T3-1, T3-2; T2, T3) comprises a first data writer (T2) comprising a control electrode configured to receive the data write gate signal (GW), an input electrode configured to receive the data voltage (VDATA) and an output electrode connected to an input electrode of the driving transistor (T1).

3. The display apparatus of claim 2, wherein the data writer (T2, T3-1, T3-2; T2, T3) further comprises a second data writer (T3-1, T3-2; T3) comprising a control electrode configured to receive the data write gate signal (GW), an input electrode connected to an output electrode of the driving transistor (T1) and an output electrode connected to the control electrode of the driving transistor (T1).

4. The display apparatus of claim 3, wherein the second data writer (T3-1, T3-2) comprises a (3-1)-th switching element (T3-1) and a (3-2)-th switching element (T3-2) which are connected in series, wherein the (3-1)-th switching element (T3-1) comprises a control electrode configured to receive the data write gate signal (GW), an input electrode connected to an output electrode of the (3-2)-th switching element (T3-2) and an output electrode connected to the control electrode of the driving transistor (T1), and wherein the (3-2)-th switching element (T3-2) comprises a control electrode configured to receive the data write gate signal (GW), an input electrode connected to the output electrode of the driving transistor (T1) and an output electrode connected to the input electrode of the (3-1)-th switching element (T3-1).

5. The display apparatus of claim 4, further comprising a stabilization capacitor (CL) comprising a first electrode configured to receive a first power voltage (ELVDD) and a second electrode connected to the input electrode of the (3-1)-th switching element (T3-1).

6. The display apparatus of claim 4 or claim 5, wherein the data initializer (T4-1, T4-2) comprises a (4-1)-th switching element (T4-1) and a (4-2)-th switching element (T4-2) which are connected in series, wherein the (4-1)-th switching element (T4-1) comprises a control electrode configured to receive the data initialization gate signal (GI), an input electrode connected to an output electrode of the (4-2)-th switching element (T4-2) and an output electrode connected to the control electrode of the driving transistor (T1), and wherein the (4-2)-th switching element (T4-2) comprises a control electrode configured to receive the data initialization gate signal (GI), an input electrode configured to receive the first initialization voltage (VINT1) and an output electrode connected to the input electrode of the (4-1)-th switching element (T4-1).

7. The display apparatus of claim 6, wherein the input electrode of the (4-1)-th switching element (T4-1) is connected to the input electrode of the (3-1)-th switching element (T3-1).

8. The display apparatus of any preceding claim, further comprising a storage capacitor (CST) comprising a first electrode configured to receive a first power voltage (ELVDD) and a second electrode connected to the control electrode of the driving transistor (T1).

9. The display apparatus of any preceding claim, wherein the organic light emitting element initializer (T7-1, T7-2) comprises a (7-1)-th switching element (T7-1) and a (7-2)-th switching element (T7-2) which are connected in series, wherein the (7-1)-th switching element (T7-1) comprises a control electrode configured to receive the organic light emitting element initialization gate signal (GB), an input electrode connected to an output electrode of the (7-2)-th switching element (T7-2) and an output electrode connected to the anode electrode of the organic light emitting element (OLED), and wherein the (7-2)-th switching element (T7-2) comprises a control electrode configured to receive the organic light emitting element initialization gate signal (GB), an input electrode configured to receive the second initialization voltage (VINT2) and an output electrode connected to the input electrode of the (7-1)-th switching element (T7-1).

10. The display apparatus of any preceding claim, wherein the light emitting controller (T5, T6) comprises a first light emitting controller (T5) comprising a control electrode configured to receive the emission signal (EM), an input electrode configured to receive a first power voltage (ELVDD) and an output electrode connected to an input electrode of the driving transistor (T1), and optionally wherein the light emitting controller (T5, T6) further comprises a second light emitting controller (T6) comprising a control electrode configured to receive the emission signal (EM), an input electrode connected to an output electrode of the driving transistor (T1) and an output electrode connected to the anode electrode of the organic light emitting element (OLED).

11. The display apparatus of any preceding claim, wherein the organic light emitting element (OLED) comprises: the anode electrode; a first light emitting layer (R1, G1, B1) disposed on the anode electrode; a second light emitting layer (R2, R2, B2) disposed on the first light emitting layer (R1, G1, B1); and a cathode electrode disposed on the second light emitting layer (R2, G2, B2).

12. The display apparatus of claim 11, wherein the organic light emitting element (OLED) further comprises: a first hole transport layer (HTL1) disposed between the anode electrode and the first light emitting layer (R1, G1, B1); a first electron transport layer (ETL1) disposed on the first light emitting layer (R1, G1, B1); a n-type charge generation layer (nCGL) disposed on the first electron transport layer (ETL1); a p-type charge generation layer (pCGL) disposed on the n-type charge generation layer (nCGL); a second hole transport layer (HTL2) disposed between the p-type charge generation layer (pCGL) and the second light emitting layer (R1, G1, B1); and a second electron transport layer (ETL2) disposed between the second light emitting layer (R1, G1, B1) and the cathode electrode and / or, wherein the organic light emitting element initialization gate signal (GB) has a phase same as a phase of the data write gate signal (GW), and / or wherein the organic light emitting element initialization gate signal (GB) has a phase same as a phase of the data initialization gate signal (GI).