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KR-102960658-B1 - PIXEL CIRCUIT AND DISPLAY DEVICE INCLUDING THE SAME

KR102960658B1KR 102960658 B1KR102960658 B1KR 102960658B1KR-102960658-B1

Abstract

The present disclosure relates to a pixel circuit and a display device including the pixel circuit, wherein a narrow bezel display device can be implemented by driving an on-bias stress (OBS) through a transistor that applies a data voltage to a driving transistor.

Inventors

  • 은주희
  • 김나영

Assignees

  • 엘지디스플레이 주식회사

Dates

Publication Date
20260507
Application Date
20201229

Claims (17)

  1. A light-emitting device comprising an anode electrode and a cathode electrode; A driving transistor having a first electrode, a second electrode and a gate electrode, and supplying a driving current to the light-emitting element; A first transistor configured to connect the second electrode and the gate electrode of the driving transistor; A second transistor configured to connect the first electrode and the data line of the driving transistor; A second power line to which an anode reset voltage is provided; Third power line to which initialization voltage is provided: A fifth transistor in which the first electrode is directly connected to the second electrode of the driving transistor and the second electrode is directly connected to the third power line; and It includes a sixth transistor in which the first electrode is directly connected to the anode electrode and the second electrode is directly connected to the second power line, and The gate electrode of the fifth transistor and the gate electrode of the sixth transistor are input with the same scan signal, Different voltages are applied to the second electrode of the fifth transistor and the second electrode of the sixth transistor, and The second transistor is activated while the first transistor is in a turned-off state to perform an on bias stress phase, and The second transistor is activated while the first transistor is in the turn-on state to perform threshold voltage sampling and data voltage programming phases of the driving transistor, and The above-mentioned on-bias stress phase includes a first on-bias stress phase and a second on-bias stress phase separated from each other, and The threshold voltage sampling and data voltage programming phases of the above driving transistor are performed between the first on-bias stress phase and the second on-bias stress phase, and A pixel circuit characterized in that the above initialization voltage is a DC voltage having a single voltage level.
  2. In paragraph 1, A pixel circuit characterized in that the voltage supplied to the data line during the above-mentioned on-bias stress phase is greater than the data voltage.
  3. delete
  4. In paragraph 1, A pixel circuit characterized in that the fifth transistor turns on before the on-bias stress phase and performs an initialization phase in which the initialization voltage is applied to the gate electrode of the driving transistor.
  5. In paragraph 1, The pixel circuit above A third transistor connected to the first electrode of the driving transistor; and A fourth transistor interposed between the second electrode of the driving transistor and the light-emitting element; additionally included, A pixel circuit characterized in that the third and fourth transistors are turned on during the light emission interval after the threshold voltage sampling and data voltage programming phases of the driving transistor.
  6. delete
  7. In paragraph 1, A pixel circuit characterized in that the sixth transistor turns on simultaneously with the fifth transistor.
  8. A display panel in which multiple pixels are arranged in a matrix form; A data driving unit that supplies data voltage and OBS voltage to the plurality of pixels through data lines connected to the plurality of pixels; and A timing controller that controls the operation timing of the data driving unit; comprising The above data driving unit A power supply unit that outputs OBS voltage, which is a DC voltage; A switching element connecting the power supply unit and the data line; and It includes a buffer connected to the above data line to output a data voltage, and The above pixel is A light-emitting device comprising an anode electrode and a cathode electrode; A driving transistor having a first electrode, a second electrode and a gate electrode, and supplying a driving current to the light-emitting element; A first transistor configured to connect the second electrode and the gate electrode of the driving transistor; A second transistor configured to connect the first electrode of the driving transistor and the data line; A second power line to which an anode reset voltage is provided; Third power line to which initialization voltage is provided: A fifth transistor in which the first electrode is directly connected to the second electrode of the driving transistor and the second electrode is directly connected to the third power line; and It includes a sixth transistor in which the first electrode is directly connected to the anode electrode and the second electrode is directly connected to the second power line, and The gate electrode of the fifth transistor and the gate electrode of the sixth transistor are input with the same scan signal, Different voltages are applied to the second electrode of the fifth transistor and the second electrode of the sixth transistor, and The above timing controller By controlling the switching element to turn on during a first period and controlling the switching element to turn off during a second period, The above data driving unit controls the OBS voltage to be output to the data line during the first section, and The second transistor is activated while the first transistor is in a turned-off state to perform an on bias stress phase, and The second transistor is activated while the first transistor is in the turn-on state to perform threshold voltage sampling and data voltage programming phases of the driving transistor, and The above-mentioned on-bias stress phase includes a first on-bias stress phase and a second on-bias stress phase separated from each other, and The threshold voltage sampling and data voltage programming phases of the above driving transistor are performed between the first on-bias stress phase and the second on-bias stress phase, and A display device characterized in that the above initialization voltage is a DC voltage having a single voltage level.
  9. In paragraph 8, A display device characterized in that the above OBS voltage is greater than the above data voltage.
  10. In paragraph 8, During the first interval, the first transistor operates in a turn-off manner, and the second transistor operates in a turn-on manner. A display device characterized in that the first transistor and the second transistor operate in a turn-on manner during the second interval.
  11. delete
  12. In paragraph 8, A display device characterized in that the fifth transistor turns on before the first section and performs an initialization phase that applies the initialization voltage to the gate electrode of the driving transistor.
  13. In Paragraph 10, The above pixel is A third transistor connected to the first electrode of the driving transistor; and A fourth transistor interposed between the second electrode of the driving transistor and the light-emitting element; additionally included, A display device characterized in that the third and fourth transistors are turned on during the light emission period after the threshold voltage sampling and data voltage programming phases of the driving transistor.
  14. delete
  15. In paragraph 8, A display device characterized in that the sixth transistor operates to turn on simultaneously with the fifth transistor.
  16. In paragraph 8, The above timing controller is a display device that applies an OBS enable signal to the gate electrode of the switching element.
  17. In Paragraph 16, A first scan signal is applied to the gate electrode of the first transistor, and a second scan signal is applied to the gate electrode of the fifth transistor, and A display device in which the first scan signal and the second scan signal are applied by a gate line placed in the same pixel row.

Description

Pixel circuit and display device including the same The present disclosure relates to a pixel circuit and a display device including the pixel circuit, wherein a narrow bezel display device can be implemented by driving an on-bias stress (OBS) through a transistor that applies a data voltage to a driving transistor. Active matrix type electroluminescent display devices include self-emitting light-emitting elements and have the advantages of fast response speed, high luminous efficiency, brightness, and viewing angle. The display device includes a gate driver that supplies gate pulses to a plurality of gate lines, and the gate driver can sequentially shift the gate pulses applied to the plurality of gate lines using a shift register. In addition, the display device may have a GIP (Gate in Panel) structure by mounting the shift register together with the pixel array on the substrate of the display panel. The display device may supply gate pulses through a double feeding method or an interlacing method by placing the shift register in the left and right bezel areas of the substrate. Research on display devices can be divided into technical and design aspects. In particular, the need for research and development in design aspects that can appeal more to consumers has recently been highlighted. Narrow bezel technology relatively increases the image display area by minimizing the left and right edges of the display panel where images are not output. Accordingly, research on narrow bezel technology, which forms narrow bezels on display devices, is also actively underway. FIG. 1 is a block diagram of an electroluminescent display device according to one embodiment of the present specification. FIG. 2 is a diagram showing the circuit configuration of a gate driver according to one embodiment of the present specification. Figure 3 is a circuit diagram showing a part of a diode connection type threshold voltage compensation pixel structure. Figure 4 is a graph showing the step waveform of the driving current of the driving transistor due to the hysteresis characteristics of the driving transistor. Figure 5 is a graph showing the drain-source current according to the gate-source voltage of the driving transistor during the threshold voltage compensation period and the light emission period of the first frame period of Figure 4. Figure 6 is a circuit diagram of a pixel circuit of an electroluminescent display device according to a comparative example. FIGS. 7 to 11 are drawings for explaining the operation of the pixel circuit and light-emitting element of FIG. 6. FIG. 12 is a detailed block diagram of a stage constituting a gate driving unit according to an embodiment. FIG. 13 is a circuit diagram of a pixel circuit of an electroluminescent display device according to an embodiment. FIG. 14 is a diagram illustrating OBS driving for a pixel circuit according to the embodiment of FIG. 13. FIG. 15 is a diagram for explaining the sampling interval for a pixel circuit according to the embodiment of FIG. 13. FIG. 16 is a diagram illustrating the control of the OBS voltage and data voltage (Vdata) supplied to the data line. The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and therefore the present invention is not limited to the depicted details. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the present invention, if it is determined that a detailed description of related prior art could unnecessarily obscure the essence of the present invention, such detailed description is omitted. Where terms such as "comprising," "having," or "consisting of" are used in this specification, other parts may be added unless "only" is used. Where a component is expressed in the singular, it includes cases where it is included in the plural unless specifically stated otherwise. In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement. In the case of describing a positional relationship, for example, when the positional relationship between two parts is described using expressions such as 'on top of,' 'above,' 'below,' or 'next to,' one or more other parts may be located between the two parts unless 'immediately' or 'directly' is used.