Display device, source driving circuit thereof and display system

Abstract

The application discloses a source driving circuit for a display device, the display device comprising a pixel circuit, the source driving circuit being configured to provide a data voltage to the pixel circuit, the source driving circuit comprising: a plurality of source driving units, each of the source driving units being configured to generate a corresponding data voltage according to image data, each of the source driving units having a first power supply end and a second power supply end, the first power supply end being connected with a first voltage, the second power supply end being connected with a second voltage, wherein there is a voltage difference between the first voltage and the second voltage, the first voltage is greater than the second voltage, and the second voltage is greater than a reference voltage, so that the source driving circuit can work in a voltage domain with a high voltage, and even if the voltage working interval is small, the source driving circuit can also work normally, and power consumption is saved.

Description

Technical Field

[0001] This invention relates to the field of display technology, and in particular to a display device, its source driving circuit, and a display system. Background Technology

[0002] In recent years, with the continuous advancement of display technology, the market demand for display devices has been increasing, and consequently, the market demand for display driver chips has also grown significantly. Display devices typically include pixel circuits and display driver chips. The display driver chip is primarily used to implement source driver circuits, gate driver circuits, and timing control circuits. The pixel circuit includes multiple pixel units. Each pixel unit is connected to the source driver circuit via a corresponding data line to receive a corresponding data voltage. Each pixel unit is also connected to the gate driver circuit via a corresponding scan line to receive a corresponding gate drive signal. The source driver circuit includes multiple operational amplifiers, each corresponding to one of the data lines. The source driver circuit provides data voltage to the corresponding data lines through these operational amplifiers. These operational amplifiers include multiple metal-oxide-semiconductor field-effect transistors (MOSFETs), hereinafter referred to as MOSFETs.

[0003] Pixel circuits can be divided into current-driven and voltage-driven types based on their driving method. With the development of AR (Augmented Reality) / VR (Virtual Reality) and the iteration of driving methods in pixel circuits with OLED (Organic Light-Emitting Diode) and EL (Electro Luminescence) evaporation, current-driven has become the mainstream driving method in pixel circuits with high brightness and aging requirements. However, when pixel circuits use current-driven methods, they often face problems such as a small data voltage range and difficulties in designing the source driving circuit.

[0004] To address the aforementioned issues, existing technologies either incorporate adjustment devices (such as PMOS transistors) in each pixel unit to expand the data voltage range of that unit, or abandon current-driven operation and directly use voltage-driven operation (source follower) to expand the data voltage range of the pixel unit. This allows the voltage domain of the source drive circuit, i.e., the operational amplifier, to be designed as the existing AVDD-GND (e.g., 6V-0V / 8V-0V / 10V-0V, etc.). However, this increases the overall power consumption of the display device. Therefore, a new display device and its source drive circuit are needed to solve these problems. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a display device and its source driving circuit and display system, thereby reducing the power consumption of the display device when the pixel circuit is current driven.

[0006] According to one aspect of the present invention, a source driving circuit for a display device is provided, the display device including a pixel circuit, the source driving circuit being used to provide a data voltage to the pixel circuit, the source driving circuit including: a plurality of source driving units, each source driving unit being used to generate a corresponding data voltage according to image data, each source driving unit having a first power supply terminal and a second power supply terminal, the first power supply terminal being connected to a first voltage, the second power supply terminal being connected to a second voltage, wherein there is a voltage difference between the first voltage and the second voltage, the first voltage being greater than the second voltage, and the second voltage being greater than a reference voltage.

[0007] Optionally, the voltage difference is set according to the data voltage range required by the pixel circuit, and the second voltage is set according to the first voltage and the voltage difference.

[0008] Optionally, each of the source drive units includes: a shift register, a data register, a data latch, a digital-to-analog converter, and an operational amplifier connected in sequence. The input terminal of the shift register is used to receive the image data, and the output terminal of the operational amplifier is used to provide the data voltage. The operational amplifier has two power supply terminals, which serve as the first power supply terminal and the second power supply terminal of the source drive unit, respectively. The operational amplifier includes multiple transistors, and the withstand voltage value of the multiple transistors is set according to the voltage difference.

[0009] Optionally, the first voltage is the power supply voltage.

[0010] Optionally, the first voltage is the high voltage in the voltage domain of the pixel circuit.

[0011] Optionally, the source drive circuit further includes: a power supply circuit, the power supply circuit including: a plurality of resistors connected between the power supply voltage and the ground voltage, for providing a plurality of power supply nodes to supply power to the operational amplifier; a first buffer, the input terminal of which is selected to be connected to one of the plurality of power supply nodes as needed, and the output terminal of which is used to provide the first voltage; and a second buffer, the input terminal of which is selected to be connected to one of the plurality of power supply nodes according to the first voltage and the voltage difference, and the output terminal of which is used to provide the second voltage.

[0012] Optionally, the input terminals of the first buffer and the second buffer are selected by a switching element to enable the selection of the power supply node.

[0013] Optionally, the reference voltage has a reference ground voltage.

[0014] According to a second aspect of the present invention, a display device is provided, comprising a plurality of scan lines and a plurality of data lines; a pixel circuit comprising a plurality of pixel units arranged in an array, each pixel unit being connected to a corresponding scan line to receive a corresponding gate drive signal, and each pixel unit being connected to a corresponding data line to receive a corresponding data voltage; a gate drive circuit for providing the corresponding gate drive signal to the plurality of scan lines respectively; and a source drive circuit as described above, wherein each source drive unit is connected to at least one of the data lines to provide the corresponding data voltage.

[0015] According to a third aspect of the present invention, a display system is provided, comprising: a display device as described above or a source drive circuit as described above.

[0016] The display device, its source driving circuit, and display system provided by this invention have an operational amplifier in the source driving circuit with a voltage domain ranging from a first voltage to a second voltage. The second voltage is no longer zero but is determined based on the data voltage range of the pixel circuit and the first voltage, and is a value greater than zero. This allows the source driving circuit to operate in a higher voltage domain, ensuring normal operation even with a narrow voltage operating range. When the pixel circuit uses current-driven operation, the source driving circuit can be well-matched to its data voltage range, eliminating the need to expand the data voltage range of the pixel circuit and increasing its applicability. Furthermore, the transistors within the operational amplifier can be configured as low-voltage tolerant components based on the voltage difference within the pixel circuit's data voltage range. Since low-voltage tolerant transistors have better component matching, the input offset voltage error between operational amplifiers can be improved, thereby mitigating problems such as uneven display, flickering, and water ripples in the display device. Simultaneously, the power consumption of the display device is reduced due to the smaller voltage difference. Attached Figure Description

[0017] The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings, in which:

[0018] Figure 1 A schematic diagram of the structure of a display device according to an embodiment of the present invention is shown;

[0019] Figure 2 A schematic diagram of the source drive unit according to an embodiment of the present invention is shown;

[0020] Figure 3 A schematic diagram of the power supply circuit of the source drive circuit according to an embodiment of the present invention is shown. Detailed Implementation

[0021] Various embodiments of the invention will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements or modules are indicated by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0022] It should be understood that, in the following description, "circuit" may include single or combined hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by the programmable circuit. When an element or circuit is said to be "connected" to another element or "connected" between two nodes, it may be directly coupled or connected to the other element, or there may be intermediate elements; the connection between elements may be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly coupled to" or "directly connected" to another element, it means that there are no intermediate elements between them.

[0023] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0024] Figure 1 A schematic diagram of the structure of a display device according to an embodiment of the present invention is shown, such as... Figure 1 As shown, the display device includes a pixel circuit 100 and a display driver chip. The display driver chip is mainly used to implement the gate drive circuit 200, the source driver circuit 300, the brightness control (EM CTRL) circuit (not shown), and the timing control circuit (not shown).

[0025] The pixel circuit 100 includes a plurality of pixel units 110 arranged in an array, and its power supply voltage is ELVDD. Each pixel unit 110 includes at least a switching transistor T1, a driving transistor T2, a capacitor C, and a light-emitting element, wherein the light-emitting element is, for example, an OLED, an LCD, or an LED. In this embodiment, the pixel circuit 100 is a matrix formed by m rows and n columns of pixel units 110 (only two rows and four columns are shown as an example in the figure). However, the embodiments of the present invention are not limited to this, and those skilled in the art can also set the pixel circuit 100 into other forms of array according to actual needs.

[0026] The gate drive circuit 200 is connected to the gate of the switch transistor T1 in each pixel unit through multiple scan lines SL[1] to SL[m] to provide the corresponding gate drive signal. Typically, the gate of the switch transistor T1 in the pixel unit 110 located in the same row is connected to the same scan line, and the gate drive signal on each scan line sequentially turns on the switch transistor T1 in each row of pixel unit 110.

[0027] The source drive circuit 300 is connected to the source of the switching transistor T1 in each pixel unit 110 through multiple data lines DL[1] to DL[n] to provide the corresponding data voltages VDATA1-VDATAn. In this embodiment, the source of the switching transistor T1 in the pixel unit 110 located in the same column is connected to the same data line to receive the same data voltage VDATA.

[0028] Specifically, the source drive circuit 300 includes multiple source drive units 310, which are respectively connected to multiple data lines DL[1] to DL[n] to provide corresponding data voltages VDATA. Each source drive unit 310 has a power supply terminal, a data input terminal, and an output terminal. The data input terminal of each source drive unit 310 receives image data PIXEL_DATA (e.g., an 8-bit digital signal), and the output terminal of each source drive unit 310 is connected to the corresponding data line to provide corresponding data voltages VDATA1-VDATAn. The power supply terminal of each source drive unit 310 includes a first power supply terminal and a second power supply terminal, wherein the first power supply terminal is connected to voltage V1, and the second power supply terminal is connected to voltage V2, that is, the voltage domain of the source drive unit 310 is V1-V2.

[0029] Figure 2 A schematic diagram of the source drive unit according to an embodiment of the present invention is shown. Figure 2 As shown, the source drive unit 310 includes a shift register 311, a data register 312, a data latch 313, a digital-to-analog converter 314, and an operational amplifier 315.

[0030] The input terminal of shift register 311 serves as the data input terminal of source driver unit 310, used to receive image data PIXEL_DATA. The image data PIXEL_DATA is passed through shift register 311, data register 312, and data latch 313 to obtain latched data. Digital-to-analog converter 314 converts the latched data in digital signal form into an analog signal form and outputs it to operational amplifier 315. Operational amplifier 315 buffers the analog data signal to obtain a data voltage VDATA representing image information, which is then provided to the corresponding pixel unit 110 through the corresponding data lines.

[0031] Operational amplifier 315 includes multiple MOSFET transistors. Operational amplifier 315 has a power supply terminal, a non-inverting input terminal, an inverting input terminal, and an output terminal. The non-inverting input terminal of each operational amplifier 315 receives an analog data signal, and the inverting input terminal and output terminal of each operational amplifier 315 are connected together to serve as the output terminal of the source driving unit 310 and connected to the corresponding data line. The power supply terminal of each operational amplifier 315 includes a first power supply terminal and a second power supply terminal. The first power supply terminal serves as the first power supply terminal of the source driving unit 310 and receives voltage V1, and the second power supply terminal serves as the second power supply terminal of the source driving unit 310 and receives voltage V2, wherein V1 > V2 > 0. The voltage difference between voltage V1 and voltage V2 is ΔV, which can be set according to the data voltage range required by the pixel unit 110 (e.g., based on the voltage difference setting of the data voltage range). Voltage V2 is set according to voltage V1 and voltage difference ΔV.

[0032] For example, if voltage V1 is the power supply voltage AVDD (the power supply voltage AVDD is the high level AVDD in the voltage domain VADD-GND of the source drive circuit in the prior art), then voltage V2 = AVDD - ΔV.

[0033] For example, when the pixel circuit 100 uses voltage-type drive and the required data voltage range is 1V-6V, that is, the voltage difference of the data voltage range is 5V, the voltage difference between voltage V1 and voltage V2 can be set to ΔV = 5V. Compared with the prior art, since the voltage difference between voltage V1 and voltage V2 is smaller, the power consumption of the source drive circuit 300 can also be reduced accordingly.

[0034] However, since the operational amplifier 315 operates at 5V, this limits the components in the operational amplifier 315 to be either medium-voltage or high-voltage resistant components. However, medium-voltage and high-voltage resistant transistor MOSFETs are prone to problems such as poor mismatch due to their characteristics. Poor mismatch of transistor MOSFETs can also lead to large input offset voltage errors between the operational amplifiers 315, which can cause problems such as uneven display, flicker, and water ripples in the display device. Therefore, larger transistor MOSFETs are needed to solve the above problems, which increases the area of ​​the display driver chip.

[0035] However, when the pixel circuit 100 uses current-driven operation and the voltage difference within the data voltage range is less than 1.2V, the voltage value of V2 can be set to V2 = V1 - ΔV = AVDD - 1.2V. In this case, the operational amplifier 315 operates within a voltage range of 1.2V, allowing the use of low-voltage MOSFETs. Since low-voltage MOSFETs are less prone to mismatch, the input offset voltage error between operational amplifiers 315 can be improved, thereby mitigating issues such as uneven display, flickering, and water ripples in the display device. Simultaneously, because the voltage difference between V1 and V2 is reduced, the power consumption of the source drive circuit 300 can also be reduced.

[0036] For example, voltage V1 can also be the voltage ELVDD that supplies power to pixel unit 110 (i.e., the high voltage in the voltage domain of pixel unit 110). Since voltage ELVDD is adjusted according to the actual situation, voltages V1 and V2 will also be adjusted according to the supply voltage ELVDD. For example, when the power supply voltage AVDD is 8V and ΔV is 1.2V, 8V≥ELVDD(V1)>1.2V, 6.8≥V2>0V.

[0037] Figure 3 A schematic diagram of the power supply circuit of the source drive circuit according to an embodiment of the present invention is shown. Figure 3 As shown, the power supply circuit includes buffer 3151, buffer 3152, and multiple resistors connected between the power supply voltage AVDD and the ground voltage GND (the figure is only illustrative and the present invention does not limit the number of resistors). The intermediate node between every two resistors (nodes A, B, C, and D in the figure) and the power supply voltage AVDD are power supply nodes, which are used to provide voltages of different values ​​to supply power to each operational amplifier 315.

[0038] Buffer 3151 has a non-inverting input, an inverting input, and an output. Its non-inverting input serves as the input of buffer 3151, and its inverting input is connected to its output, together serving as the output of buffer 3151. Buffer 3152 has a non-inverting input, an inverting input, and an output. Its non-inverting input serves as the input of buffer 3152, and its inverting input is connected to its output, together serving as the output of buffer 3152.

[0039] When voltage V1 is the power supply voltage AVDD, the input terminal of buffer 3151 is connected to the power supply voltage AVDD, and the output terminal of buffer 3151 provides the power supply voltage AVDD. The input terminal of buffer 3152 is selected to be connected to a power supply node according to the voltage difference ΔV between voltage V1 and voltage V2, and the output terminal of buffer 3152 provides voltage V2.

[0040] When voltage V1 is the voltage ELVDD supplying power to pixel unit 110, the input terminal of buffer 3151 is selected to connect to a power supply node as needed, and the output terminal of buffer 3151 provides voltage ELVDD(V1). The input terminal of buffer 3152 is selected to connect to a power supply node based on the voltage difference ΔV between voltage V1 and voltage V2, and the output terminal of buffer 3152 provides voltage V2. Because voltage ELVDD is greater than voltage V2, the power supply node connected to the input terminal of buffer 3151 is closer to the power supply voltage AVDD than the power supply node connected to the input terminal of buffer 3152. For example, assuming that the resistance values ​​of multiple resistors between the power supply voltage AVDD and the ground voltage GND are equal, then during the dynamic adjustment of voltage V1 and voltage V2 with voltage ELVDD, it is only necessary to ensure that the number of resistors between voltage V1 and voltage V2 is equal to ensure that the voltage difference ΔV between voltage V1 and voltage V2 remains constant.

[0041] For example, the inputs of buffers 3151 and 3152 are used to select the power supply node via switching elements.

[0042] According to the display device and its source driving circuit provided in the embodiment of the present invention, the low voltage of the operational amplifier 315 in the source driving circuit 310 is no longer zero, but is determined according to the voltage difference ΔV between voltage V1 and voltage V2, and is a value greater than zero. In this way, the source driving circuit 300 will operate in a voltage domain with a relatively high voltage. Even if its voltage operating range is small, the source driving circuit 300 can still operate normally. Moreover, since the voltage difference of the supply voltage of the source driving circuit 300 is reduced, the power consumption of the source driving circuit 300 can also be reduced.

[0043] When the pixel circuit 100 is driven by current, the source drive circuit 300 can be well matched with its data voltage range without expanding the data voltage range of the pixel circuit 100, thus increasing the applicability of the source drive circuit 300. Furthermore, the transistor MOSFETs in the operational amplifier 315 can be set as low-voltage resistant components according to the voltage difference of the data voltage range of the pixel circuit 100. Since the low-voltage resistant transistor MOSFETs have good component matching, the error of the input offset voltage between each operational amplifier 315 can be improved without increasing the area of ​​the transistor MOSFETs. This can improve problems such as uneven display, flickering, and water ripples in the display device. Moreover, since the voltage difference of the supply voltage of the source drive circuit 300 is reduced, the power consumption of the source drive circuit 300 can also be reduced.

[0044] It should be noted that the source drive circuit or display device provided in the embodiments of the present invention can be applied to a display system to improve display quality.

[0045] As described above, these embodiments of the present invention do not exhaustively describe all details, nor do they limit the invention to specific embodiments. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. The scope of protection of this invention should be determined by the scope defined in the claims and their equivalents.

Claims

1. A source driver circuit for a display device, the display device comprising a pixel circuit, the source driver circuit configured to provide a data voltage to the pixel circuit, the source driver circuit comprising: a plurality of source driver units, each of the source driver units configured to generate a corresponding data voltage according to image data, each of the source driver units having a first power supply terminal and a second power supply terminal, the first power supply terminal connected to a first voltage, the second power supply terminal connected to a second voltage, each of the source driver units comprising: a shift register, a data register, a data latch, a digital-to-analog converter and an operational amplifier connected in sequence, an input terminal of the shift register configured to receive the image data, an output terminal of the operational amplifier configured to provide the data voltage, the operational amplifier having two power supply terminals as the first power supply terminal and the second power supply terminal of the source driver unit respectively, wherein the first voltage and the second voltage have a voltage difference, the first voltage is greater than the second voltage, the second voltage is greater than a reference voltage, the voltage difference is set according to a data voltage range required by the pixel circuit, the second voltage is set according to the first voltage and the voltage difference, and the reference voltage has a reference ground voltage. 2.The source driver circuit of claim 1, wherein wherein the operational amplifier comprises a plurality of transistors, and voltage withstand values of the plurality of transistors are set according to the voltage difference.

3. The source driving circuit according to claim 1, wherein the first voltage is a power supply voltage.

4. The source driving circuit according to claim 1, wherein the first voltage is a high voltage of a voltage domain of the pixel circuit. 5.The source driver circuit of claim 2, further comprising: a power supply circuit, the power supply circuit comprising: a plurality of resistors connected between a power supply voltage and a ground voltage, configured to provide a plurality of power supply nodes for supplying power to the operational amplifier; a first buffer, an input terminal of the first buffer configured to select one of the plurality of power supply nodes according to a requirement, and an output terminal of the first buffer configured to provide the first voltage; a second buffer, an input terminal of the second buffer configured to select one of the plurality of power supply nodes according to the first voltage and the voltage difference, and an output terminal of the second buffer configured to provide the second voltage.

6. The source driving circuit according to claim 5, wherein the selection of the power supply nodes by the input terminals of the first buffer and the second buffer is realized by a switching element. 7.A display device, comprising: a plurality of scan lines and a plurality of data lines; a pixel circuit comprising a plurality of pixel units arranged in an array, each of the pixel units connected to a corresponding scan line to receive a corresponding gate drive signal, and each of the pixel units connected to a corresponding data line to receive a corresponding data voltage; a gate driver circuit configured to provide the corresponding gate drive signals to the plurality of scan lines respectively; the source driver circuit of any one of claims 1 to 6, wherein each of the source driver units is connected to at least one of the data lines to provide the corresponding data voltage. 8.A display system, comprising: the display device of claim 7 or the source driver circuit of any one of claims 1 to 6.

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