Pixel driving circuit and driving method

Abstract

The application provides a pixel driving circuit and a driving method. The pixel driving circuit comprises a first driving sub-circuit configured to control current flowing from a power positive signal ELVDD to a second node N2; a first data writing unit configured to transmit a first data signal Data-A to a first node N1 in response to a first scanning signal G_out; a first light-emitting control unit configured to control coupling between the second node N2 and a third node N3 under control of a second scanning signal E_out; a second driving sub-circuit configured to control current flowing from the power positive signal ELVDD to a fifth node N2'; a second data writing unit configured to transmit a second data signal Data-B to a fourth node N1' in response to a third scanning signal G_out'; and a second light-emitting control unit configured to control coupling between the fifth node N2' and the third node N3 under control of a fourth scanning signal E_out'.

Description

Technical Field

[0001] This invention relates to the field of display panel technology, and more specifically, to a pixel driving circuit and driving method. Background Technology

[0002] Currently, active matrix organic light-emitting diode (AMOLED) displays are widely used in various electronic products due to their many advantages, such as being thinner and lighter, actively emitting light, having no viewing angle issues, low cost, low energy consumption, and flexible display capabilities.

[0003] The principle of AMOLED grayscale selection lies in the data voltage controlling the current flowing through the OLED device to achieve grayscale switching at different brightness levels. In existing pixel circuits, the driving transistors (DTFTs) mostly use single-oxide transistors or low-temperature polysilicon (LTPS) transistors. When using single-oxide transistors, due to their low electron mobility, achieving high brightness requires a larger area occupied by oxide transistors compared to LTPS transistors, making them difficult to use in high pixel density (HPPI) products. When using single-LTPS transistors, in actual manufacturing, under low current conditions, the uniformity of transistors across multiple points on the panel is poor, with large dispersion, easily leading to uneven low grayscale levels, thus affecting the display effect.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the problems in the prior art, the present invention aims to provide a pixel driving circuit and driving method, which can achieve high brightness of the display panel while improving low grayscale and display effect.

[0006] Specifically, a first aspect of the present invention provides a pixel driving circuit, comprising:

[0007] The first driving sub-circuit is configured to control the current flowing from the positive power supply signal ELVDD to the second node N2;

[0008] The first data writing unit is configured to transmit the first data signal Data-A to the first node N1 in response to the first scan signal G_out;

[0009] The first light-emitting control unit is configured to control the coupling between the second node N2 and the third node N3 under the control of the second scan signal E_out;

[0010] The second driving sub-circuit is configured to control the current flowing from the positive power supply signal ELVDD to the fifth node N2';

[0011] The second data writing unit is configured to transmit the second data signal Data-B to the fourth node N1' in response to the third scan signal G_out'.

[0012] The second light-emitting control unit is configured to control the coupling between the fifth node N2' and the third node N3 under the control of the fourth scan signal E_out';

[0013] The third node N3 is used to couple the anode of a light-emitting diode.

[0014] According to a first aspect of the invention, the first driving sub-circuit includes a first driving transistor T1;

[0015] The second driving sub-circuit includes a fourth driving transistor T1';

[0016] The first driving transistor T1 is a low-temperature polysilicon transistor;

[0017] The fourth driving transistor T1' is an oxide transistor.

[0018] According to a first aspect of the present invention, the first data writing unit includes a second switching transistor T2, wherein the second switching transistor T2 is a single-gate transistor or a multi-gate transistor.

[0019] The second data writing unit includes a fifth switching transistor T2', which is a single-gate transistor or a multi-gate transistor.

[0020] According to a first aspect of the present invention, the pixel driving circuit further includes a first storage capacitor and a second storage capacitor;

[0021] The first storage capacitor is located between the positive power supply signal ELVDD and the first node N1;

[0022] The second storage capacitor is located between the positive power supply signal ELVDD and the fourth node N1'.

[0023] According to a first aspect of the invention, the pixel driving circuit further includes a comparator:

[0024] The comparator is configured to compare the relationship between the Data voltage of the driver chip and a set fixed voltage, and to input the Data voltage to the Data-A data line or the Data-B data line according to the relationship between the Data voltage of the driver chip and the set fixed voltage.

[0025] A second aspect of the present invention provides a driving method for a pixel driving circuit, applicable to the pixel driving circuit described in the first aspect, the driving method comprising the following steps:

[0026] Determine the relationship between the Data voltage and the set fixed voltage;

[0027] If it is determined that the Data voltage is less than or equal to the set fixed voltage, the Data voltage is input to the Data-A data line of the pixel driving circuit and the first driving transistor T1 is turned on, while the third scan signal G_out' is at the off potential.

[0028] If it is determined that the Data voltage is greater than the set fixed voltage, the Data voltage is input to the Data-B data line of the pixel driving circuit and the fourth driving transistor T1' is turned on, while the first scan signal G_out is at the off potential.

[0029] According to a second aspect of the present invention, the fixed voltage is the data voltage value corresponding to pixels with gray levels of 4 to 32.

[0030] Compared with the prior art, the pixel driving circuit of the present invention includes driving sub-circuits of low temperature polycrystalline silicon transistors (LTPS TFTs) and oxide transistors, respectively, thereby realizing the switching between the two sub-circuits when different driving voltages are applied, achieving high brightness of the display panel while improving low grayscale and display effect. Attached Figure Description

[0031] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Other features, objects, and advantages of the invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without inventive effort. Furthermore, the drawings are merely illustrative diagrams of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0032] Figure 1This is a schematic diagram of the pixel driving circuit according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the array substrate of an OLED display according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the pixel driving circuit according to another embodiment of the present invention; and

[0035] Figure 4 This is a flowchart of a pixel driving circuit driving method according to another embodiment of the present invention. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed herein. The present invention can also be implemented or applied through other different specific embodiments, and various details in the present invention can be modified or changed according to different viewpoints and application systems without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0037] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can readily implement it. The present invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0038] In the representation of this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics represented in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. Furthermore, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate different embodiments or examples represented in this invention, as well as features of different embodiments or examples, without contradiction.

[0039] Furthermore, the terms "first" and "second" are used for illustrative purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the representation of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0040] To clearly illustrate the present invention, components unrelated to the description are omitted, and the same or similar constituent elements throughout the specification are given the same reference numerals.

[0041] Throughout this specification, when it is said that a device is "connected" to another device, this includes not only "direct connection" but also "indirect connection" by placing other components in between. Furthermore, when it is said that a device "comprises" a certain constituent element, unless otherwise stated otherwise, this does not exclude other constituent elements, but rather implies that other constituent elements may be included.

[0042] When we say that a device is "above" another device, this can mean that it is directly above the other device, or it can mean that other devices are present in between. Conversely, when we say that a device is "directly" "above" another device, there are no other devices present in between.

[0043] Although the terms first, second, etc., are used in some instances herein to refer to various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, first interface and second interface, etc., are used. Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of features, steps, operations, elements, components, items, kinds, and / or groups, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0044] The technical terms used herein are for reference only to specific embodiments and are not intended to limit the invention. The singular form used herein includes the plural form unless the statement explicitly indicates otherwise. The word "comprising" as used in this specification means to specify a particular characteristic, region, integer, step, operation, element, and / or component, and does not exclude the presence or addition of other characteristics, regions, integers, steps, operations, elements, and / or components.

[0045] Although not explicitly defined, all terms, including technical and scientific terms used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries shall be further interpreted as having a meaning consistent with relevant technical literature and the content of this present instruction, and shall not be over-interpreted as having an ideal or overly formulaic meaning unless otherwise defined.

[0046] The pixel driving circuit and driving method of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments are not intended to limit the scope of protection of the present invention.

[0047] This invention provides a pixel driving circuit. Figure 1 This is a schematic diagram of a pixel driving circuit according to an embodiment of the present invention. The pixel driving circuit includes:

[0048] The first driving sub-circuit, in Figure 1 In one embodiment, the first driving sub-circuit includes a first driving transistor T1. The control electrode of the first driving transistor T1 is coupled to a first node N1, the first electrode of the first driving transistor T1 is coupled to a positive power supply signal ELVDD, and the second electrode of the first driving transistor T1 is coupled to a second node N2. That is, the first driving sub-circuit is configured to control the current flowing from the positive power supply signal ELVDD to the second node N2. It should be noted that in the pixel driving circuit of the present invention, the control electrode of each thin-film transistor is the gate of the transistor, the first electrode is one of the source and drain of the transistor, and the second electrode is the other of the source and drain of the transistor.

[0049] A first data writing unit is configured to transmit a first data signal Data-A to a first node N1 in response to a first scan signal G_out. The first data writing unit includes a second switching transistor T2, the control electrode of which is coupled to the first scan signal G_out, and its first and second electrodes are coupled to the first data signal Data-A and the first node N1, respectively. The second switching transistor T2 can be a single-gate transistor or a multi-gate transistor.

[0050] The first light-emitting control unit is configured to control the coupling between the second node N2 and the third node N3 under the control of the second scan signal E_out. The first light-emitting control unit may include a third switching transistor T3, the control electrode of the third switching transistor T3 is coupled to the second scan signal E_out, the first electrode of the third switching transistor T3 is coupled to the second node N2, and the second electrode of the third switching transistor T3 is coupled to the third node N3. At this time, the third switching transistor T3 controls the coupling between the second node N2 and the third node N3 under the control of the second scan signal E_out.

[0051] The second driving sub-circuit includes a fourth driving transistor T1', the control electrode of which is coupled to the fourth node N1', the first electrode of which is coupled to the positive power supply signal ELVDD, and the second electrode of which is coupled to the fifth node N2'. That is, the second driving sub-circuit is configured to control the current flowing from the positive power supply signal ELVDD to the fifth node N2'.

[0052] The second data writing unit is configured to transmit the second data signal Data-B to the fourth node N1' in response to the third scan signal G_out'. The second data writing unit includes a fifth switching transistor T2', whose control electrode is coupled to the third scan signal G_out', and whose first and second electrodes are coupled to the second data signal Data-B and the fourth node N1', respectively. The fifth switching transistor T2' can be a single-gate transistor or a multi-gate transistor. Preferably, the fifth switching transistor T2' is a dual-gate transistor.

[0053] The second light-emitting control unit is configured to control the coupling between the fifth node N2' and the third node N3 under the control of the fourth scan signal E_out'. The second light-emitting control unit may include a sixth switching transistor T3', the control electrode of the sixth switching transistor T3' is coupled to the fourth scan signal E_out', the first electrode of the sixth switching transistor T3' is coupled to the fifth node N2', and the second electrode of the sixth switching transistor T3' is coupled to the third node N3. At this time, the sixth switching transistor T3' controls the coupling between the fifth node N2' and the third node N3 under the control of the fourth scan signal E_out'.

[0054] The third node N3 is used to couple the anode of a light-emitting diode (LED), and the cathode of the LED is coupled to the negative power supply signal ELVEE.

[0055] In this invention, the first driving transistor T1 and the fourth driving transistor T1' are different thin-film transistors. Specifically, the first driving transistor T1 can be a low-temperature polycrystalline silicon transistor (LPTS TFT), and the fourth driving transistor T1' is an oxide transistor; or conversely, the first driving transistor T1 is an oxide transistor, and the fourth driving transistor T1' is a low-temperature polycrystalline silicon transistor. The pixel driving circuit of this invention includes driving sub-circuits with driving transistors of low-temperature polycrystalline silicon and oxide transistors, thereby realizing the switching between the two sub-circuits at different driving voltages, thereby achieving high brightness of the display panel while improving low grayscale and display effect.

[0056] In some embodiments, the pixel driving circuit further includes a first storage capacitor C1 and a second storage capacitor C2, wherein the first storage capacitor C1 is disposed between the power supply positive signal ELVDD and the first node N1; and the second storage capacitor C2 is disposed between the power supply positive signal ELVDD and the fourth node N1'.

[0057] In practical applications, the pixel driving circuit also includes a comparator (not shown in the figures). Typically, the comparator is located in the IC chip or flexible printed circuit board (FPC). The comparator is configured to compare the relationship between the driver chip's Data voltage and a set fixed voltage, and to input the Data voltage to the Data-A or Data-B data line based on this relationship. Of course, in other embodiments, the pixel driving circuit may also include an initialization unit and a compensation unit, etc.

[0058] Figure 2 This is a schematic diagram of the array substrate of a display according to an embodiment of the present invention. When the pixel driving circuit of the present invention is applied to the array substrate of an OLED display, the array substrate of the OLED display includes m rows of pixels. Each row of pixels is controlled by a GOA driving unit (Gate Driver On Array, array substrate row driving scan circuit) and an EOA driving unit (Emitgate Driver On Array, light emission control signal driving circuit). The voltage at the output terminal of the GOA driving unit is input to the first scan signal G_out or the third scan signal G_out' of the pixel driving circuit, and the voltage at the output terminal of the EOA driving unit is input to the second scan signal E_out or the fourth scan signal E_out' of the pixel driving circuit. See [link to diagram]. Figure 3 .

[0059] The present invention also provides a driving method for a pixel driving circuit, applicable to the above-mentioned pixel driving circuit. The driving transistor and each switching transistor of the above-mentioned pixel driving circuit can be P-type transistors, such as PMOS transistors, or N-type transistors, such as NMOS transistors.

[0060] Taking the first driving transistor T1 as a low-temperature polysilicon transistor and the fourth driving transistor T1' as an oxide transistor as an example, Figure 4 This is a flowchart of a pixel driving circuit driving method according to another embodiment of the present invention. Specifically, the driving method includes the following steps:

[0061] Step S100: Determine the relationship between the Data voltage and the set fixed voltage; Step S100 is usually completed in the IC chip;

[0062] If the Data voltage is determined to be less than or equal to the set fixed voltage, then step 210 is executed: the Data voltage is input to the Data-A data line of the pixel driving circuit and the first driving transistor T1 is turned on, while the third scan signal G_out' is at the off potential; taking the driving transistor and each switching transistor of the pixel driving circuit as PMOS transistors as an example, when the third scan signal G_out' (the control terminal of the transistor) is at a high potential, it is the off potential, and when the third scan signal G_out' is at a low potential, it is the on potential.

[0063] If the Data voltage is determined to be greater than the set fixed voltage, then step 220 is executed: the Data voltage is input to the Data-B data line of the pixel driving circuit, causing the fourth driving transistor T1' to turn on, while the first scan signal G_out is at the off potential. Taking the pixel driving circuit where the driving transistor and each switching transistor are PMOS transistors as an example, the first scan signal G_out is at the off potential when it is high, and at the on potential when it is low.

[0064] In practice, the fixed voltage setting is set to the data voltage value corresponding to pixels with gray levels of 4 to 32. The fixed voltage setting for gray levels can be selected according to the product application field, product brightness and other indicators.

[0065] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0066] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A pixel driving circuit, characterized in that, include: The first driving sub-circuit is configured to control the current flowing from the positive power supply signal ELVDD to the second node N2; The first data writing unit is configured to transmit the first data signal Data-A to the first node N1 in response to the first scan signal G_out; The first light-emitting control unit is configured to control the coupling between the second node N2 and the third node N3 under the control of the second scan signal E_out; The second driving sub-circuit is configured to control the current flowing from the positive power supply signal ELVDD to the fifth node N2'; The second data writing unit is configured to transmit the data signal Data-B to the fourth node N1' in response to the third scan signal G_out'. The second light-emitting control unit is configured to control the coupling between the fifth node N2' and the third node N3 under the control of the fourth scan signal E_out'; The third node N3 is used to couple the anode of a light-emitting diode.

2. The pixel driving circuit according to claim 1, characterized in that, The first driving sub-circuit includes a first driving transistor T1; The second driving sub-circuit includes a fourth driving transistor T1'; The first driving transistor T1 is a low-temperature polysilicon transistor; The fourth driving transistor T1' is an oxide transistor.

3. The pixel driving circuit according to claim 1, characterized in that, The first data writing unit includes a second switching transistor T2, which is a single-gate transistor or a multi-gate transistor; The second data writing unit includes a fifth switching transistor T2', which is a single-gate transistor or a multi-gate transistor.

4. The pixel driving circuit according to claim 1, characterized in that, The pixel driving circuit also includes a first storage capacitor and a second storage capacitor. The first storage capacitor is located between the positive power supply signal ELVDD and the first node N1; The second storage capacitor is located between the positive power supply signal ELVDD and the fourth node N1'.

5. The pixel driving circuit according to claim 2, characterized in that, The pixel driving circuit also includes a comparator: The comparator is configured to compare the relationship between the Data voltage of the driver chip and a set fixed voltage, and to input the Data voltage to the Data-A data line or the Data-B data line according to the relationship between the Data voltage of the driver chip and the set fixed voltage.

6. A driving method for a pixel driving circuit, characterized in that, The driving method applicable to the pixel driving circuit of claim 5 includes the following steps: determining the relationship between the Data voltage and a set fixed voltage; If it is determined that the Data voltage is less than or equal to the set fixed voltage, the Data voltage is input to the Data-A data line of the pixel driving circuit and the first driving transistor T1 is turned on, while the third scan signal G_out' is at the off potential. If it is determined that the Data voltage is greater than the set fixed voltage, the Data voltage is input to the Data-B data line of the pixel driving circuit and the fourth driving transistor T1' is turned on, while the first scan signal G_out is at the off potential.

7. The driving method for the pixel driving circuit according to claim 6, characterized in that, The fixed voltage is set to the data voltage value corresponding to pixels with gray levels of 4 to 32.

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