Pre-charging circuit and method, driving chip and display device

Abstract

The invention discloses a pre-charging circuit and method, a driving chip and a display device. The pre-charging circuit comprises a plurality of first charging units, and each first charging unit is connected with a corresponding data channel; the first charging units are connected with all data channels of the display panel, the second charging units are connected with all data channels of the display panel, the first charging units are used for being started according to the first control signals so as to provide first pre-charging actions for the corresponding data channels, and the second charging units are used for being started according to the second control signals so as to connect all the data channels to equal potentials. Through the first charging unit and the second charging unit which work in stages, the pre-charging speed and the consistency of the pre-charging voltage of each data channel are considered, and the display quality is improved.

Description

Technical Field

[0001] The present invention relates to the field of display technologies, and particularly to a pre-charge circuit and method, a chip, and a display device. Background Art

[0002] LED display panels are usually driven in a line-by-line scanning manner. During the line-by-line scanning process, the phenomenon that LED beads are dimly lit due to the charging and discharging of the parasitic capacitance of the data channel is called the ghosting phenomenon. Specifically, the ghosting phenomenon is further divided into upper ghosting and lower ghosting. Among them, lower ghosting refers to when the nth row is scanned, the parasitic capacitance of the data channel is discharged to a low potential; when the (n + 1)th row is scanned, the voltage difference between the row transistor and the parasitic capacitance will form a charging path for the parasitic capacitance, resulting in the LED beads being dimly lit.

[0003] In the prior art, a pre-charge circuit is used to charge the parasitic capacitance to a reference potential at the moment of line change. When the next line is turned on, the voltage difference between the row transistor voltage and the parasitic capacitance is reduced, so that lower ghosting can be avoided, and the problem of dim first row can also be solved.

[0004] Figure 1A and Figure 1B are a common anode LED driving circuit and a common cathode LED driving circuit with a pre-charge function in the prior art. Referring to Figure 1A and Figure 1B , the driving circuit of the LED includes an output circuit and a pre-charge circuit that are directly connected to the data channel (i.e., the OUT terminal of the driving chip) and work in stages. When the PWM signal is at the first level, the output circuit is open, the pre-charge circuit is controlled by the control signal to be turned on, and provides a pre-charge voltage to the data channel according to the reference potential; when the PWM signal is at the second level, the output circuit provides a driving current to the LED beads, and at this time the pre-charge circuit is controlled by the control signal to be turned off.

[0005] However, due to the gradual increase in the size and resolution of the display panel, the total capacitance load of the pre-charge circuit increases, and how to improve the performance of the pre-charge circuit has become an urgent problem to be solved. Summary of the Invention

[0006] In view of the above problems, the purpose of the present application is to provide a pre-charge circuit and method, a driving chip, and a display device.

[0007] According to a first aspect of the present application, a pre-charge circuit is provided, wherein the pre-charge circuit is configured to provide a pre-charge voltage to each data channel of a display panel, and the pre-charge circuit includes: a plurality of first charging units, each of the first charging units being connected to a corresponding one of the data channels; and a second charging unit, being connected to all the data channels of the display panel, wherein the plurality of first charging units are configured to be turned on according to a first control signal to provide a first pre-charge operation to the corresponding data channels, and the second charging unit is configured to be turned on according to a second control signal to connect all the data channels to an equal potential.

[0008] Optionally, the first charging unit includes: a first operational amplifier, having an input terminal receiving a reference voltage, an output terminal connected to the corresponding data channel, and providing the first pre-charge operation when the first control signal has an effective level.

[0009] Optionally, the second charging unit includes: a plurality of switching elements, a first end of each of the switching elements being connected to a first node, a second end being connected to the corresponding data channel, and the switching elements closing and connecting the first node and each of the data channels when the second control signal has an effective level.

[0010] Optionally, the second charging unit further includes: a second operational amplifier, having an input terminal receiving the reference voltage, an output terminal connected to the first node, and the second operational amplifier providing the reference voltage to the first node at least when the second control signal has an effective level.

[0011] Optionally, the first control signal has an effective level starting from a first moment, a moment when the pulse width modulation signal of any of the data channels jumps to a first level is not later than the first moment, the first control signal has an invalid level starting from a second moment, and the second control signal has an effective level starting from the second moment; the second control signal has an invalid level starting from a third moment, and a moment when any of the pulse width modulation signals jumps to a second level is not earlier than the third moment.

[0012] Optionally, the first moment and the second moment are separated by a first preset duration, and the second moment and the third moment are separated by a second preset duration.

[0013] Optionally, the pre-charge circuit further includes a plurality of resistors, and each of the first charging units and the second charging unit are connected to the corresponding data channel via the corresponding resistor.

[0014] According to a second aspect of the present application, a pre-charging method is provided. The pre-charging method is used to provide a pre-charging voltage to each data channel of a display panel. The pre-charging method includes: providing respective first pre-charging actions to the data channels; and connecting all the data channels to an equal potential.

[0015] According to a third aspect of the present application, a driving chip is provided. The driving chip includes: the pre-charging circuit as described in any one of the above; and an output circuit for providing a driving current to the display panel.

[0016] According to a fourth aspect of the present application, a display device is provided. The display device includes: a display panel; and the driving chip as described above for providing a pre-charging voltage or driving to the data channels of the display panel.

[0017] According to the pre-charging circuit and method, driving chip, and display device provided by the present application, by providing respective independent first pre-charging actions to each data channel, the load is lighter, which is conducive to the rapid change of the potential of the data channels, realizing rapid pre-charging; by connecting the data channels to an equal potential, the error between different channels can be eliminated, improving the display uniformity. Therefore, the pre-charging circuit and method, driving chip, and display device provided by the present application can balance the speed of pre-charging and the consistency of the pre-charging voltage of each data channel, and can also have a higher refresh rate and a more stable display effect in the case of high-resolution display. Description of the Drawings

[0018] Through the following description of the embodiments of the present invention with reference to the drawings, the above and other objects, features, and advantages of the present invention will become clearer. In the drawings:

[0019] Figure 1A Showing the common anode driving circuit of LEDs in the prior art;

[0020] Figure 1B Showing the common cathode driving circuit of LEDs in the prior art;

[0021] Figure 2 Showing the schematic structural diagram of the driving chip according to the first embodiment of the present application;

[0022] Figure 3 Showing the schematic working waveform diagram of the pre-charging circuit according to the first embodiment of the present application;

[0023] Figure 4 Showing the schematic structural diagram of the driving chip according to the second embodiment of the present application;

[0024] Figure 5 Showing the schematic working waveform diagram of the pre-charging circuit according to the second embodiment of the present application;

[0025] Figure 6Schematic flowchart showing the pre-charging method according to an embodiment of the present application. Detailed implementation manners

[0026] The various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In the respective drawings, the same elements are denoted by the same or similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale.

[0027] Meanwhile, in this specification and the claims, certain terms are used to refer to specific components. Those of ordinary skill in the art should understand that a manufacturer may use different terms to refer to the same component. This specification and the claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction.

[0028] It should be understood that in the following description, a "circuit" may include a single or a combination of multiple hardware circuits, programmable circuits, state machine circuits, and / or elements capable of storing instructions executed by a programmable circuit. When an element or circuit is said to be "connected to" another element or when an element or circuit is said to be "connected between" two nodes, it may be directly coupled or connected to another element or there may be intermediate elements, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, 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 the two.

[0029] In addition, it should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, 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 variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, article or device including the said element.

[0030] It should also be noted that in the various methods and processes of the present application, the magnitude of the serial numbers of the steps does not mean the order of execution, nor does it constitute any limitation on the implementation process of the embodiments of the present application.

[0031] The present application discloses a pre - charge circuit, which is used to provide a pre - charge voltage to each data channel of a display panel. The pre - charge circuit includes a plurality of first charging units and second charging units. Each first charging unit is connected to a corresponding data channel and is used to be turned on according to a first control signal to provide a first pre - charge operation to the corresponding data channel. The second charging unit is connected to all the data channels of the display panel and is used to be turned on according to a second control signal to connect all the data channels to an equal potential.

[0032] The pre - charge circuit disclosed in the present application will be further described below with reference to specific embodiments.

[0033] Figure 2 A schematic structural diagram of a driving chip in the first embodiment is shown. The driving chip in the first embodiment includes an output circuit 10 and a pre - charge circuit 100 of the first embodiment. Among them, the output circuit 10 and the pre - charge circuit 100 work in stages to provide a driving current or a pre - charge voltage to each data channel of the display panel. Taking the data channel OUT1 as an example, when the pulse - width modulation signal PWM1 corresponding to the data channel OUT1 has a first level, the output circuit 10 - 1 is open - circuited with the data channel OUT1, and the pre - charge circuit provides a pre - charge voltage to the data channel OUT1; when the pulse - width modulation signal PWM1 has a second level, the pre - charge circuit is turned off, and the corresponding output circuit 10 - 1 is connected to the data channel OUT1 and provides a driving current. The above - mentioned first level is, for example, a low level, and the second level is, for example, a high level.

[0034] In Figure 2 the driving circuits 10 - 1 and 10 - n corresponding to the data channel OUT1 and the data channel OUTn are exemplarily shown. Among them, the output circuit 10 can be implemented with reference to any relevant technology and will not be elaborated here.

[0035] Referring to Figure 2 the pre - charge circuit 100 includes a plurality of first charging units 120 and a second charging unit 110.

[0036] The first charging units 120 correspond one - to - one with the data channels OUT. Each of the first charging units 120 is controlled by a first control signal CS1 and provides a first pre - charge operation when the first control signal CS1 has an effective level.

[0037] Exemplarily, each first charging unit 120 includes a first operational amplifier OP1. The input terminal of each first operational amplifier OP1 receives a reference voltage, and the output terminal is connected to the corresponding data channel OUT. During the effective level of the first control signal CS1, a first pre-charging operation is provided to the corresponding data channel OUT according to the reference voltage. It should be noted that the reference voltages received by the first operational amplifiers OP1 are the same, and the potential of this reference voltage can be adjusted according to the actual working conditions. Providing the first pre-charging operation to each data channel via the corresponding first charging unit is more conducive to achieving fast pre-charging.

[0038] The second charging unit 110 is connected to all the data channels OUT, and is used to be turned on according to the second control signal CS2 to connect all the data channels OUT to an equal potential. Through the connection of equal potentials, the mismatch of the pre-charging voltages between the data channels OUT can be eliminated, thereby improving the consistency of the pre-charging voltages of the data channels OUT, which is more conducive to improving the display uniformity.

[0039] In the first embodiment, refer to Figure 2 , the second charging unit 110 includes a plurality of switching elements S corresponding to each data channel OUT and a second operational amplifier OP2. The input terminal of the second operational amplifier OP2 receives the above-mentioned reference voltage, and the output terminal is connected to the first node A. The first ends of the switching elements S are connected to the first node A, and the second ends are respectively connected to the corresponding data channels OUT. Each switching element S is controlled by the second control signal CS2. In Figure 2 , exemplarily, the switching elements S1 and Sn corresponding to the data channel OUT1 and the data channel OUTn are shown.

[0040] Furthermore, in some embodiments, the pre-charging circuit further includes resistors R1-Rn corresponding to each data channel OUT one by one. Each first charging unit 120 and the switching element S are connected to the corresponding data channel OUT via the corresponding resistor R.

[0041] Figure 3 FIG. shows a schematic working waveform diagram of the pre-charging circuit according to the first embodiment of the present application. Refer to Figure 3 , taking the example of providing pre-charging voltages to four data channels OUT-a, OUT-b, OUT-c, and OUT-d, the working process of the pre-charging circuit 100 will be specifically described. Among them, when the pulse width modulation signal PWM corresponding to each data channel OUT has a first level, the pre-charging circuit 100 provides a pre-charging voltage to the data channel OUT according to the first control signal CS1 and the second control signal CS2. When the pulse width modulation signal PWM has a second level, a driving current is provided to the data channel OUT by the corresponding output circuit. Wherein the first level is, for example, a low level, and the second level is, for example, a high level.

[0042] Specifically, the pre-charging phase T3, that is, the phase in which the pre-charging voltage is provided by the pre-charging circuit 100, includes a first phase T1 and a second phase T2. In the first phase T1, a first pre-charging operation is provided by the first charging unit 120, and in the second phase T2, the second charging unit 110 isopotentially connects each data channel. Among them, since the voltage cannot jump, the second phase T2 usually ends at the fourth moment t4, that is, when the pre-charging voltage of each data channel OUT drops to the corresponding low level. Starting from the first moment t1, the first control signal CS1 has an effective level, and the first phase T1 starts; starting from the second moment t2, the first control signal CS1 has an invalid level, and the second control signal CS2 has an effective level, the first phase T1 ends, and the second phase T2 starts; starting from the third moment t3, the second control signal CS2 has an invalid level. It should be noted that since the voltage cannot jump, the second phase T2 usually ends at the fourth moment t4, that is, when the pre-charging voltage of each data channel OUT drops to the corresponding low level.

[0043] Furthermore, in the pre-charging circuit 100 of the first embodiment of the present application, the moment when the pulse width modulation signal PWM of any data channel OUT jumps to the first level is not later than the first moment t1, and the moment when the pulse width modulation signal PWM of any data channel OUT jumps to the second level is not earlier than the third moment t3. That is to say, for any one data channel OUT, at the latest starting from the first moment t1, the first charging unit 120 corresponding to it provides the first pre-charging operation; for any one data channel OUT, at the earliest starting from the third moment t3, the corresponding output circuit provides the drive current. By way of example, in Figure 3 the moment when the pulse width modulation signals PWM-b and PWM-d jump to the first level is earlier than the first moment t1, so before the moment t1, that is, Figure 3 in the T4 phase of, the pre-charging voltage provided to the data channels OUT-b and OUT-d is in a floating state. Similarly, the moment when the pulse width modulation signals PWM-c and PWM-d jump to the second level is later than the third moment t3, so after the moment t3, that is, Figure 3 in the T5 phase of, the pre-charging voltage provided to the data channels OUT-c and OUT-d is also in a floating state. It should be noted that Figure 3 the T4 phase and the T5 phase in are only for example. In actual working conditions, controlled by the rising edge of the corresponding PWM signal, the duration of the T4 phase and / or the T5 phase of different data channels is not necessarily the same.

[0044] Further, in some embodiments, a first preset duration is set between a first moment t1 and a second moment t2, and a second preset duration is set between the second moment t2 and a third moment t3. The first preset duration and the second preset duration can be set with reference to the refresh rate of the display panel and the display period of each data channel. In some embodiments, it can also be set that the first preset duration is less than the second preset duration, which can leave a time margin for adjusting the voltage consistency of each data channel and further improve the elimination effect of the pre-charge voltage error between each data channel.

[0045] Further, in some embodiments, the second operational amplifier OP2 is in a normally open state, that is to say, the second operational amplifier OP2 continuously provides a reference voltage to the first node A. In some embodiments, the second operational amplifier OP2 can also be controlled by a corresponding control signal and provide a reference voltage to the first node A at least during the T2 stage, that is, at least during the valid level period of the second control signal CS2. Controlling the working state of the second operational amplifier OP2 can reduce the power consumption of the pre-charge circuit.

[0046] Figure 4 The schematic structural diagram of the driving chip according to the second embodiment of the present application is shown. The driving chip of this second embodiment includes an output circuit 10 and a pre-charge circuit 200 of the second embodiment. Among them, the output circuit 10 and the pre-charge circuit 200 work in stages to provide driving current or pre-charge voltage to each data channel of the display panel.

[0047] The output circuit 10 can also be implemented with reference to any relevant technology and will not be elaborated here.

[0048] Reference Figure 5 , the pre-charge circuit 200 includes a plurality of first charging units 220 and a second charging unit 210.

[0049] The first charging units 220 correspond to the data channels OUT one by one, and may include a first operational amplifier OP1, and provide a first pre-charge action to their respective data channels OUT when the first control signal CS1 has an effective level.

[0050] Different from the first embodiment, in the second embodiment, the second charging unit 210 only includes a plurality of switching elements S. The first ends of these switching elements S are connected together and connected to the first node A, and the second ends are connected to their respective corresponding data channels. These switching elements S are controlled by the second control signal CS2 to conduct, so as to connect all the data channels, thereby realizing the equipotential connection of each data channel. At this time, each data channel OUT is in a floating state.

[0051] It should be noted that, in some embodiments, the second charging unit 210 may also include a second operational amplifier OP2 whose output terminal is connected to the first node A, but the second operational amplifier OP2 does not operate.

[0052] Further, in some embodiments, the pre-charge circuit further includes resistors R1-Rn corresponding to each data channel OUT one by one. Each first charging unit 220 and the switching element S are connected to the corresponding data channel through the corresponding resistor.

[0053] Figure 5 The schematic working waveform diagram of the pre-charge circuit in the second embodiment of the present application is shown. Refer to Figure 5 , also taking the example of providing a pre-charge voltage to four data channels OUT-a, OUT-b, OUT-c, and OUT-d. When the pulse width modulation signal PWM corresponding to each data channel OUT has a first level, the pre-charge circuit 200 provides a pre-charge voltage to the data channel OUT according to the first control signal CS1. When the pulse width modulation signal PWM has a second level, the corresponding output circuit provides a drive current to the data channel OUT. The first level is, for example, a low level, and the second level is, for example, a high level.

[0054] In the pre-charge circuit 200 of the second embodiment, similarly, starting from the first moment t1, the first control signal CS1 has an effective level; starting from the second moment t2, the first control signal CS1 has an invalid level, and the second control signal CS2 has an effective level. Starting from the third moment t3, the second control signal CS2 has an invalid level. However, the pre-charge circuit 200 in the second embodiment only provides a pre-charge voltage in the first stage T6, that is, between the first moment t1 and the second moment t2. At the second moment t2, until the pulse width modulation signal PWM of the corresponding data channel OUT jumps to the second level, the data channel OUT remains in a floating state, and, because the pulse width modulation signals PWM of different data channels OUT are different, the duration of the floating state is also different, for example, it can be Figure 5 T7-a, T7-b, T7-c, and T7-d in Figure 5 . It should be understood that, as

[0055] Similar to the first embodiment, in the pre-charge circuit of the second embodiment of the present application, the moment when the pulse-width modulation signal of any data channel OUT jumps to the first level is not later than the first moment t1, and the moment when the pulse-width modulation signal of any data channel OUT jumps to the second level is not earlier than the third moment t3. Among them, in some embodiments, the first moment t1 and the second moment t2 are set to be separated by a first preset duration, and the second moment t2 and the third moment t3 are set to be separated by a second preset duration. The first preset duration and the second preset duration can be set with reference to the refresh rate of the display panel and the display period of each data channel. In some embodiments, the first preset duration can also be set to be less than the second preset duration, which can leave a time margin for adjusting the voltage consistency of each data channel and further improve the elimination effect of the pre-charge voltage error between each data channel.

[0056] It should be noted that although the pre-charge circuit 100 of the above first embodiment and the pre-charge circuit 200 of the above second embodiment both take the common anode connection as an example, it should be understood that the pre-charge circuit provided in the present application can also be applied to the common cathode connection.

[0057] Figure 6 A schematic flowchart showing the pre-charge method of the embodiment of the present application is shown. This pre-charge method is used to provide a pre-charge voltage to each data channel of the display panel. In some embodiments, this pre-charge method can be implemented by the pre-charge circuit provided in the present application. This pre-charge method includes the following steps:

[0058] Step S11: Provide respective first pre-charge actions to the data channels.

[0059] In this step, the first pre-charge actions of each data channel are independent of each other. At this time, the load is relatively light and the voltage changes quickly, so rapid pre-charging can be achieved.

[0060] Step S12: Connect all data channels to an equal potential.

[0061] After the first pre-charge action, the data channels are connected by an equal potential, thereby eliminating the mismatch between the data channels and improving the potential consistency of each data channel.

[0062] In some embodiments, in step S12, each data channel can be connected to the same power supply node, and the same pre-charge voltage is provided to each data channel by this power supply node.

[0063] In some embodiments, in step S12, all data channels can also be connected to achieve equal potential connection.

[0064] The present application also provides a display device. The display device includes a display panel and a driving circuit. Among them, the display panel can be an LED display panel. The driving circuit can be the driving circuit provided by the present application or a driving circuit including the pre-charge circuit in the present application. The driving circuit is used to provide a driving current or a pre-charge voltage for a plurality of data channels of the display panel.

[0065] According to the pre-charge circuit and method, driving chip, and display device provided by the present application, by providing respective independent first pre-charge actions to each data channel, the load is lighter, which is beneficial to the rapid change of the potential of the data channel and realizes rapid pre-charging; by connecting each data channel at the same potential, the error between different channels can be eliminated and the display uniformity can be improved. Therefore, the pre-charge circuit and method, driving chip, and display device provided by the present application can balance the speed of pre-charging and the consistency of the pre-charge voltage of each data channel, and can also have a higher refresh rate and a more stable display effect in the case of high-resolution display.

[0066] In accordance with the embodiments of the present application as described above, these embodiments do not describe all the details in detail, nor do they limit the present application to only the specific embodiments. Obviously, according to the above description, many modifications and variations can be made. The present specification selects and specifically describes these embodiments in order to better explain the principle and practical application of the present application, so that those skilled in the art can make good use of the present application and its modifications based on the present application. The protection scope of the present application shall be subject to the scope defined by the claims of the present application.

Claims

1. A pre-charging circuit, wherein: The pre-charging circuit is used to provide a pre-charging voltage to each data channel of the display panel, and the pre-charging circuit includes: a plurality of first charging units, each of the first charging units being connected to a corresponding data channel; and A second charging unit is connected to all data channels of the display panel, The plurality of first charging units are used to be turned on according to a first control signal to provide a first pre-charging action to the corresponding data channels, and the second charging unit is used to be turned on according to a second control signal to connect all the data channels to an equal potential.

2. The precharge circuit according to claim 1, wherein: The first charging unit comprises: The first operational amplifier has an input terminal receiving a reference voltage, an output terminal connected to the corresponding data channel, and provides the first pre-charging action when the first control signal has a valid level.

3. The precharge circuit according to claim 1, wherein: The second charging unit comprises: A plurality of switch elements, each of which has a first end connected to a first node and a second end connected to a corresponding data channel, and the switch element is closed and connects the first node with each data channel when the second control signal has a valid level.

4. The precharge circuit according to claim 3, wherein: The second charging unit further includes: The second operational amplifier has an input terminal receiving the reference voltage and an output terminal connected to the first node. The second operational amplifier provides the reference voltage to the first node at least when the second control signal has a valid level.

5. The precharge circuit according to any one of claims 2 to 4, wherein: The first control signal has a valid level from a first moment, and the pulse width modulation signal of any of the data channels jumps to the first level at a time no later than the first moment, The first control signal has an invalid level from a second moment, and the second control signal has a valid level from the second moment; The second control signal has an invalid level from a third moment, and the moment when any of the pulse width modulation signals jumps to the second level is no earlier than the third moment.

6. The precharge circuit according to claim 5, wherein: The first moment is separated from the second moment by a first preset time length, and the second moment is separated from the third moment by a second preset time length.

7. The precharge circuit according to claim 1, wherein: The pre-charging circuit further includes a plurality of resistors, and each of the first charging unit and the second charging unit is connected to the corresponding data channel via the corresponding resistor.

8. A pre-charging method, wherein: The precharging method is used to provide a precharging voltage to each data channel of the display panel, and the precharging method includes: providing respective first pre-charging actions to the data channels; and Connect all data channels to equal potential.

9. A driver chip, wherein: include: The pre-charging circuit according to any one of claims 1 to 7; as well as The output circuit is used to provide a driving current to the display panel.

10. A display device, wherein: include: Display panel; as well as The driver chip as claimed in claim 9 is used to provide a pre-charge voltage or drive to the data channel of the display panel.

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