CN111901932A - Display device - Google Patents
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- CN111901932A CN111901932A CN202010857296.4A CN202010857296A CN111901932A CN 111901932 A CN111901932 A CN 111901932A CN 202010857296 A CN202010857296 A CN 202010857296A CN 111901932 A CN111901932 A CN 111901932A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/34—Voltage stabilisation; Maintaining constant voltage
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/63—Generation or supply of power specially adapted for television receivers
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/10—Controlling the intensity of the light
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
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- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
The embodiment of the application provides a display device, the feedback sampling point is arranged at the output part of a filter circuit in the display device, so that the voltage of a variable voltage part can be indirectly regulated by sampling the output voltage of the filter circuit, and the control on the LED driving voltage is completed, thereby not only realizing timely feedback to regulate the variable voltage when the variable voltage fluctuates, but also timely feedback to regulate the variable voltage when the fixed voltage fluctuates, and effectively solving the problem of unstable voltage; and voltage ripples in the output voltage of a fixed voltage power supply unit in the display device are filtered through the filter circuit, so that the condition of unstable voltage caused by introducing other ripples or noise in feedback sampling is avoided, and the problem of unstable voltage in the power supply process of the power supply circuit is further solved.
Description
Technical Field
The present application relates to the field of electronic technology, and in particular, to a display device.
Background
Currently, with the development of electronic technology, electronic devices including display devices, such as televisions, have more and more functions, and users have higher and higher requirements for displaying the display devices in the televisions. Taking a television as an example, in a display device of the television, a power supply circuit is arranged to drive at least one Light Emitting Diode (LED) Light bar to illuminate a display screen of the television.
In the prior art, a power supply circuit commonly used includes: the LED lamp driving circuit comprises a Power supply, a filtering and rectifying module, a Power Factor Correction (PFC) module, an LLC module and a load, wherein the load at least comprises a main board and a plurality of paths of LED lamp strip driving. When the power supply circuit supplies power to a load, alternating current voltage output by the power supply firstly passes through the filtering and rectifying module, the filtering and rectifying module converts the alternating current voltage output by the power supply into direct current voltage, the direct current voltage is input to the PFC module for waveform processing, the LLC module of the power supply circuit receives the direct current voltage processed by the PFC module through the primary winding of the LLC module, and different secondary windings output different voltages according to the voltage of the primary winding to supply power to different loads.
However, with the above power supply circuit, in practical applications, the problem of cross-tuning frequency between different windings may occur, thereby causing voltage instability.
Disclosure of Invention
The embodiment of the application provides a display device, and the problem of unstable voltage in the power supply process of a power supply circuit is solved.
In a first aspect, an embodiment of the present application provides a display device, which may include: the LED drive circuit comprises a power supply circuit, an LED drive circuit connected with the power supply circuit, a filter circuit and a feedback circuit, wherein the filter circuit is also connected with the feedback circuit.
Wherein the power supply circuit is configured to supply power to the LED driving circuit; the power supply circuit comprises a fixed voltage power supply unit and a variable voltage power supply unit, wherein the fixed voltage power supply unit is superposed on the variable voltage power supply unit to realize step power supply to the LED drive circuit.
The filter circuit is configured to filter a voltage ripple in an output voltage of the fixed voltage power supply unit.
The feedback circuit is configured to sample an output voltage of the filter circuit and feed back a variation of the output voltage to a controller of the varying voltage power supply unit.
The controller is configured to control the voltage of the variable voltage power supply unit according to the feedback of the feedback circuit.
In one possible implementation, the filter circuit includes a first resistor and a first capacitor.
One end of the first resistor is connected with the output end of the fixed voltage power supply unit and the LED drive circuit respectively.
The other end of the first resistor is connected with one end of the first capacitor and the feedback circuit respectively.
The other end of the first capacitor is connected with the fixed voltage power supply unit and the variable voltage power supply unit respectively.
In a possible implementation manner, the bandwidth frequency of the filter circuit is greater than the frequency of the voltage ripple in the fixed voltage power supply unit and is less than the frequency of the switching ripple output by the power supply module corresponding to the fixed winding in the fixed voltage power supply unit.
In one possible implementation, the feedback circuit includes: a feedback resistance unit and a differential feedback unit.
The feedback resistance unit is respectively connected with the output end of the filter circuit, the LED drive circuit and the controller.
The differential feedback unit is respectively connected with the output end of the filter circuit and the feedback resistance unit.
In one possible implementation, the feedback resistance unit includes: the circuit comprises a second resistor, a third resistor, a fourth resistor and a fifth resistor.
And one end of the second resistor is connected with the output end of the filter circuit.
The other end of the second resistor is connected with one end of the third resistor and one end of the fifth resistor.
The other end of the third resistor is connected with one end of the fourth resistor and the controller;
the other end of the fourth resistor is grounded.
The other end of the fifth resistor is connected with the LED driving circuit.
In one possible implementation, the differential feedback unit includes: a second capacitance.
And one end of the second capacitor is connected with the output end of the filter circuit.
The other end of the second capacitor is connected with one end of the fifth resistor.
In one possible implementation, the differential feedback unit includes: a second capacitor and a sixth resistor.
And one end of the sixth resistor is connected with the output end of the filter circuit.
The other end of the sixth resistor is connected with one end of the second capacitor.
The other end of the second capacitor is connected with one end of the fifth resistor.
In one possible implementation, the variable voltage power supply unit includes: the controller comprises a power supply module, the controller, a field effect tube, a diode, an inductor and a third capacitor, wherein the controller is in a fixed on-time COT mode.
The power supply module is connected with the controller.
The controller is connected with one end of the inductor.
The other end of the inductor is connected with one end of the third capacitor.
The other end of the third capacitor is grounded.
In one possible implementation, the variable voltage power supply unit further includes a seventh resistor.
One end of the seventh resistor is connected with one end of the third capacitor.
The other end of the seventh resistor is connected with the other end of the third capacitor.
In a possible implementation manner, the capacitance value of the third capacitor is smaller than the capacitance value of the second capacitor, and a difference value between the capacitance value of the third capacitor and the capacitance value of the second capacitor is smaller than a difference threshold.
According to the display device provided by the embodiment of the application, the feedback sampling points are arranged at the output part of the filter circuit in the display device, so that the voltage of the variable voltage part can be indirectly regulated by sampling the output voltage of the filter circuit, and the control on the LED driving voltage is completed, therefore, the regulation of the variable voltage can be timely fed back when the variable voltage is sent to fluctuate, the regulation of the variable voltage can be timely fed back when the fixed voltage fluctuates, and the problem of unstable voltage is effectively solved; and voltage ripples in the output voltage of a fixed voltage power supply unit in the display device are filtered through the filter circuit, so that the condition of unstable voltage caused by introducing other ripples or noise in feedback sampling is avoided, and the problem of unstable voltage in the power supply process of the power supply circuit is further solved.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a display device provided with an independent power panel according to an embodiment of the present application;
fig. 2 is a schematic diagram illustrating a connection relationship between a power board and a load according to an embodiment of the present disclosure;
fig. 3 is a schematic structural diagram of a power supply circuit provided in the prior art;
fig. 4 is a schematic structural diagram of a possible display device according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a display device according to an embodiment of the present disclosure;
fig. 6 is a schematic structural diagram of another display device provided in the embodiment of the present application;
fig. 7 is a schematic structural diagram of another display device according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The following first describes a scenario in which the present application is applied and problems that may occur with reference to the drawings. As the demand for obtaining information is continuously increasing, various types of display devices, such as computers, televisions, projectors, and the like, are being developed. The power supply circuit is one of the most important circuit structures in the display device, and the power supply circuit can provide electric energy for the display device, so that the display device can normally operate. Some display devices are provided with independent power panels, and some display devices combine the power panels and the main board into a whole.
Taking a display device provided with an independent power board as an example, a structure of the display device is described, referring to fig. 1, fig. 1 is a schematic structural diagram of a display device provided with an independent power board according to an embodiment of the present application, and as shown in fig. 1, the display device includes a panel 1, a backlight assembly 2, a main board 3, a power board 4, a rear case 5, and a base 6. Wherein, the panel 1 is used for presenting pictures for users; the backlight assembly 2 is located below the panel 1, usually some optical assemblies, and is used for supplying sufficient light sources with uniform brightness and distribution, so that the panel 1 can normally display images, the backlight assembly 2 further includes a back plate 20, the main board 3 and the power board 4 are arranged on the back plate 20, usually some convex hull structures are formed by punching on the back plate 20, and the main board 3 and the power board 4 are fixed on the convex hulls through screws or hooks; the rear shell 5 is covered on the panel 1 to hide the parts of the display device such as the backlight assembly 2, the main board 3 and the power panel 4, and the like, thereby achieving the effect of beautiful appearance; and a base 6 for supporting the display device.
Further, fig. 2 is a schematic diagram of a connection relationship between a power panel and a load according to an embodiment of the present application, as shown in fig. 2, the power panel 4 includes an input end 41 and an output end 42 (a first output end 421, a second output end 422, and a third output end 423 are shown in the figure), where the input end 41 is connected to a mains supply, the output end 42 is connected to the load, for example, the first output end 421 is connected to an LED light bar for lighting a display screen, the second output end 422 is connected to an audio, and the third output end 423 is connected to a main board. The power panel 4 needs to convert ac power into dc power required by the load, and the dc power is usually in different specifications, for example, 18V is required for sound, 12V is required for panel, etc.
When a power supply circuit supplies power to a load, in order to reduce the area of a Printed Circuit Board (PCB) where the power supply circuit is located and improve efficiency, the power supply circuit of the display device may be configured to be a voltage that is supplied to at least one LED light bar by the sum of voltages respectively output by two different secondary windings of a first resonant conversion circuit (LLC) and a second LLC, and a voltage adjustment module in the power supply circuit is configured to only need to perform boost or buck adjustment on the voltage output by the secondary winding of the first LLC, and the sum of the adjusted voltage and the voltage output by the secondary winding of the second LLC is used together to supply power to the multiple LED light bars, so as to reduce the requirement on the withstand voltage values of elements such as a switching tube and a capacitor in the voltage adjustment module, and further, the cost of the power supply circuit is finally reduced, and the efficiency is improved. For example, as shown in fig. 3, fig. 3 is a schematic structural diagram of a power supply circuit provided in the prior art, and a more general power supply circuit includes: the Power supply 11, the filter rectifier module 12, the Power Factor Correction (PFC) module 13, the LLC module 14, and the load. Wherein the load includes at least the main board 18 and the multiple LED light bar drivers 16 shown in the figure.
Specifically, when the power supply circuit supplies power to a load, the ac voltage output by the power supply 11 first passes through the filtering and rectifying module 12, the filtering and rectifying module 12 converts the ac voltage output by the power supply into a dc voltage, and inputs the dc voltage to the PFC module 13 for waveform processing, the LLC module 14 of the power supply circuit receives the dc voltage processed by the PFC module 14 through the primary winding 141 thereof, and different secondary windings output different voltages according to the voltage of the primary winding 141 to supply power to different loads. For example, the secondary winding 144 provides 12V to the motherboard 18 based on the voltage of the primary winding 141.
Set up two different LLC secondary winding in LLC module 14 and supply power for multichannel LED lamp strip, include: a first LLC secondary winding 142 and a second LLC secondary winding 143; wherein, the output end a of the first secondary winding 142 outputs a first voltage, and the output end c of the second secondary winding 143 outputs a second voltage; the output end a of the second secondary winding 143 is connected to the input end b of the first secondary winding 142; meanwhile, the input end b and the output end c of the first LLC secondary winding 142 are both connected to the voltage adjustment module 15, the voltage adjustment module 15 may be configured to adjust the first voltage output by the first LLC secondary winding 142, note that the voltage adjusted by the voltage adjustment module 15 is a third voltage, and send the third voltage output by the voltage adjustment module 15 and the second voltage output by the second LLC secondary winding 143 to the multiple LED drivers 16, and the multiple LED drivers 16 supply power to the multiple LED light bars according to the sum of the second voltage and the third voltage.
At this time, the second voltage output by the secondary winding 143 of the second LLC corresponds to a "fixed voltage" that does not change, and the third voltage output by the voltage adjustment module 15 corresponds to a "variable voltage" that changes, so that the multiple LED light bars are supplied with the superimposed fixed second voltage on the basis of the variable voltage, and this supply form may also be referred to as "step supply".
Optionally, the first voltage output by the first LLC secondary winding is less than the second voltage output by the second LLC secondary winding.
It is understood that, as shown in fig. 3, only the 16V/18V voltage of the main board is taken as an exemplary illustration, if the variation range required by the third voltage is within 12V, the secondary winding providing 12V voltage for the main board may be taken as the first LLC secondary winding; or, in other possible implementations, the secondary winding that provides a certain voltage for other loads may also be used as the first LLC secondary winding, and the like, which are implemented in the same manner as the principle and are not described again.
However, with the above-described power supply circuit shown in fig. 3, in practical applications, a problem of cross-tuning frequency between different windings may occur, thereby causing voltage instability.
When power is supplied through a power supply circuit in the display device, the problem of unstable voltage is solved, and in a conceivable feedback design idea, feedback can be set at the output end of the variable voltage, so that the voltage of the power supply circuit can be adjusted based on the voltage output of the variable voltage, and the voltage is stable. For example, please refer to fig. 4, where fig. 4 is a schematic structural diagram of a possible display device provided in the embodiment of the present application, and the display device may include a power supply circuit, a light emitting diode LED driving circuit, and a feedback circuit. The power supply circuit is used for supplying power to the LED drive circuit; the power supply circuit comprises a fixed voltage power supply unit and a variable voltage power supply unit, and the fixed voltage power supply unit is superposed on the variable voltage power supply unit to realize step power supply to the LED drive circuit; the feedback circuit is used for sampling the output voltage of the fixed voltage power supply unit and feeding back the change of the output voltage to the controller of the variable voltage power supply unit; the controller is used for controlling the voltage of the variable voltage power supply unit according to the feedback of the feedback circuit.
It can be seen that, with the display device shown in fig. 4, the voltage is adapted to be adjusted by sampling and feeding back the output end of the fixed voltage power supply unit of the power supply circuit for stepped power supply, so that when the variable voltage is sent to fluctuate, the variable voltage can be fed back in time to be adjusted, and when the fixed voltage fluctuates, the variable voltage can be fed back in time to be adjusted, so that stable output voltage can be obtained in multi-path LED driving, and the problem of unstable voltage can be effectively solved. However, with the display device shown in fig. 4, when the feedback circuit performs feedback sampling, since the fixed voltage power supply unit is also a part of the switching power supply, the switching current of the switching power supply will generate a voltage ripple having the same frequency as the switching power supply due to the capacitance of the capacitor in the feedback resistor and the ESR, and similarly, when the DC-DC module is in the operating state, the output capacitor of the DC-DC module will also generate an operating ripple, so when the feedback circuit performs feedback, the feedback circuit will not only feed back the collected DC component voltage output by the DC-DC module outputting the feedback sampling voltage to the controller of the variable voltage power supply unit, but also feed back the voltage ripple in the output voltage of the fixed voltage power supply unit and the operating ripple output by the DC-DC module to the controller of the variable voltage power supply unit, this introduces other ripples or noise in the feedback samples. When other ripples or noises are introduced into the feedback sampling, the voltage waveform is also changed, namely, the problem of unstable voltage occurs, so that the turn-on time of the DC-DC module in the COT mode is influenced.
In order to solve the problem of introducing other ripples or noises into the feedback sampling, an easily conceivable technical solution is: simply reducing the voltage ripple in the output voltage of the fixed voltage power supply unit, reducing the ESR or increasing the output capacitance, etc., but this approach is costly and not effective either; the other technical scheme is as follows: other modes of DC-DC modules are used, such as current mode or voltage mode, but if the operational ripple of this topology current has less effect on the feedback sampling, its performance and cost will be affected.
Based on the above series of considerations, the present application provides a display device, which may include a power supply circuit, a light emitting diode LED driving circuit connected to the power supply circuit, a filter circuit, and a feedback circuit, where the filter circuit is further connected to the feedback circuit; when the power supply circuit supplies power to the LED drive circuit, the feedback sampling point can be arranged at the output part of the filter circuit, the feedback circuit samples the output voltage of the filter circuit and feeds back the change of the output voltage to the controller of the variable voltage power supply unit, so that the controller can control the voltage of the variable voltage power supply unit according to the feedback of the feedback circuit to complete the control of the LED drive voltage, thereby not only realizing the timely feedback of the adjustment of the variable voltage when the variable voltage sends fluctuation, but also timely feeding back the adjustment of the variable voltage when the fixed voltage fluctuates, and effectively solving the problem of unstable voltage; and voltage ripples in the output voltage of the fixed voltage power supply unit are filtered through the filter circuit, so that the problem of unstable voltage caused by introducing other ripples or noises in feedback sampling is avoided, and the problem of unstable voltage is further solved.
The technical solutions of the embodiments of the present application will be described in detail below with specific examples. It is understood that, in the embodiments of the present application, the following specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.
Fig. 5 is a schematic structural diagram of a display device according to an embodiment of the present application, and for example, please refer to fig. 5, the display device may include a power supply circuit, a light emitting diode LED driving circuit connected to the power supply circuit, a filter circuit, and a feedback circuit, and the filter circuit is further connected to the feedback circuit.
Wherein the power supply circuit is configured to supply power to the LED drive circuit; the power supply circuit comprises a fixed voltage power supply unit and a variable voltage power supply unit, and the fixed voltage power supply unit is superposed on the variable voltage power supply unit to realize step power supply to the LED drive circuit.
A filter circuit configured to filter a voltage ripple in an output voltage of the fixed voltage power supply unit.
A feedback circuit configured to sample the output voltage of the filter circuit and to feed back a variation of the output voltage to a controller of the varying voltage power supply unit.
And a controller configured to control the voltage of the variable voltage power supply unit according to feedback of the feedback circuit.
Therefore, in the embodiment of the application, the feedback sampling point is arranged at the output part of the filter circuit in the display device, so that the voltage of the variable voltage part can be indirectly regulated by sampling the output voltage of the filter circuit, and the control on the LED driving voltage is completed, thereby not only realizing the timely feedback regulation of the variable voltage when the variable voltage is sent to fluctuate, but also timely feedback regulation of the variable voltage when the fixed voltage fluctuates, and effectively solving the problem of unstable voltage; and voltage ripples in the output voltage of a fixed voltage power supply unit in the display device are filtered through the filter circuit, so that the condition of unstable voltage caused by introducing other ripples or noise in feedback sampling is avoided, and the problem of unstable voltage in the power supply process of the power supply circuit is further solved.
Based on the embodiment shown in fig. 5, it can be seen that, in the embodiment of the present application, by providing the filter circuit, the purpose is to: the filter circuit is used for filtering the voltage ripple in the output voltage of the fixed voltage power supply unit, and therefore, the filter circuit needs to have a sufficient bandwidth, and moreover, since the operating ripple output by the DC-DC module is a common-mode ripple, in order to avoid attenuation influence of the filter circuit on the operating ripple output by the DC-DC module, the bandwidth design of the filter circuit is crucial. In general, two factors need to be considered when setting the bandwidth of the filter circuit:
In combination with the above-mentioned factor 1 and factor 2, the filter module that needs to be set up can filter the voltage ripple in the output voltage of the fixed voltage power supply unit, and can reduce the attenuation of the switching ripple output by the DC-DC module, so that the switching ripple output by the DC-DC module includes as much as possible in the controller that feeds back to the variable voltage power supply unit in the feedback sampling, and therefore, in this embodiment of the present application, the bandwidth frequency of the filter circuit may be greater than the frequency of the switching ripple output by the power supply module corresponding to the fixed winding in the fixed voltage power supply unit, and is less than the frequency of the switching ripple output by the power supply module corresponding to the fixed winding in the. For example, the bandwidth frequency of the filter circuit may be any value between more than 1Khz and less than 60Khz, and in order to ensure the filtering effect, the bandwidth frequency of the filter circuit may be set to be 2Khz to 10 Khz.
It can be understood that the filter circuit shown above may have various designs, for example, the filter circuit may be an LC filter circuit, an RC filter circuit, or other types of filter circuits, and may be specifically set according to actual needs, as long as it can implement not only filtering out voltage ripples in the output voltage of the fixed voltage power supply unit, but also reducing attenuation of switching ripples output by the DC-DC module.
Taking a filter circuit as an RC filter circuit as an example, in a possible implementation manner, the filter circuit includes a first resistor and a first capacitor, for example, please refer to fig. 6, fig. 6 is a schematic structural diagram of another display device provided in the embodiment of the present application, wherein one end of the first resistor is connected to the output end of the fixed voltage power supply unit and the LED driving circuit respectively; the other end of the first resistor is connected with one end of the first capacitor and the feedback circuit respectively; the other end of the first capacitor is connected with the fixed voltage power supply unit and the variable voltage power supply unit respectively.
In the embodiment of the present application, the number of resistors and capacitors specifically included in the filter circuit, and the connection relationship between the resistors, or the connection relationship between the capacitors may be set according to an actual application scenario, which is not specifically limited in the embodiment of the present application.
In conjunction with the display device shown in fig. 6, the first resistor and the first capacitor may form a low-pass filter circuit, and after the voltage ripple in the output voltage of the fixed voltage power supply unit passes through the low-pass filter circuit, the voltage ripple in the output voltage may be greatly attenuated. And, for the DC-DC module, the first resistor and the second resistor, the third resistor and the fourth resistor in the feedback circuit may form a high-pass filter circuit, the high pass filter circuit may effectively include the switching ripple output by the DC-DC block in feedback samples to the controller of the varying voltage supply unit, therefore, not only can the voltage ripple in the output voltage of the fixed voltage power supply unit be filtered, but also the attenuation of the switching ripple output by the DC-DC module can be reduced, the switching ripple output by the DC-DC module is fed back to the controller of the variable voltage power supply unit in the feedback sampling as much as possible, thereby avoiding voltage instability caused by introducing other ripples or noise in the feedback sampling, therefore, the problem of unstable voltage in the power supply process of the power supply circuit in the COT mode is solved, and the stable work of the DC-DC module is ensured.
In combination with the above description about the bandwidth frequency of the filter circuit, in the embodiment of the present application, when the filter circuit includes the first resistor and the first capacitor, if the value of the first resistor is larger, the value of the first capacitor is smaller, so that although the bandwidth position of the filter circuit can be made to be about 2Khz to 10Khz, if the switching ripple output by the DC-DC module passes through the first capacitor, a larger attenuation is caused, which is not favorable for the stable operation of the DC-DC module, and therefore, in a normal case, the first resistor having a smaller resistance value and the first capacitor having a larger capacitance value may be set. For example, if the resistance of the first resistor in the filter circuit may be 200 ohms and the capacitance of the first capacitor may be 100n, the bandwidth frequency of the filter circuit is 5 Khz.
Assuming that the feedback sampling voltage collected by the feedback circuit is U, the voltage U1 output by the fixed voltage power supply unit includes a DC component voltage U1 and a voltage ripple Δ U1, and the voltage U2 output by the DC-DC module includes a DC component voltage U2 and an operating ripple Δ U2, if the display device shown in fig. 4 is used, the feedback sampling voltage collected by the feedback circuit is U1+ U2U 1+ Δ U1+ U2+ Δ U2, it can be seen that the feedback sampling voltage collected by the feedback circuit includes the voltage ripple Δ U1 output by the fixed voltage power supply unit and the operating ripple Δ U2 output by the DC-DC module, but with the display device shown in fig. 5 or fig. 6 provided in this embodiment of the present application, by providing the filter circuit composed of the first resistor and the first capacitor, the voltage ripple Δ U1 output by the fixed voltage power supply unit is greatly attenuated after passing through the filter circuit, the feedback sampling voltage collected by the feedback circuit is U1+ U2U 1+ U2+ delta U2, not only are switching voltage ripples in the output voltage of the fixed voltage power supply unit filtered, but also voltage fluctuation in the fixed voltage power supply unit can be made to be included in the feedback sampling as far as possible and fed back to the controller of the variable voltage power supply unit, so that the problem of unstable voltage in the power supply process of the power supply circuit in the COT mode is solved, and the stable operation of the DC-DC module is ensured.
For example, the display device shown in fig. 5 may further include a display screen, where the display screen is configured to display an image, and when the LED driving circuit drives at least one LED light bar, the at least one LED light bar is used to light the display screen. Under the scheme, the sampling point of the feedback is arranged at the output part of the filter circuit in the display device, so that the voltage of the variable voltage part can be indirectly regulated by sampling the output voltage of the filter circuit, and the control of the LED driving voltage is completed.
In one possible implementation, the feedback circuit may include: a feedback resistance unit and a differential feedback unit; the feedback resistance unit is respectively connected with the output end of the filter circuit, the LED drive circuit and the controller; the differential feedback unit is respectively connected with the output end of the filter circuit and the feedback resistance unit.
In the embodiment of the present application, the number of resistors specifically included in the feedback resistor unit and the connection relationship between the resistors may be set according to an actual application scenario, which is not specifically limited in the embodiment of the present application; the differential feedback unit may include capacitive devices, and specific numbers, types, and the like of the capacitive devices, and the embodiments of the present application are not particularly limited.
It can be understood that, in the embodiment of the present application, by providing the differential feedback unit in the feedback circuit, feed-forward is increased, so that the output voltage ripple can be reduced, and the voltage stability of the output to the LED driving circuit can be improved.
In one possible implementation, the feedback resistance unit may include: the second resistor, the third resistor, the fourth resistor and the fifth resistor; as shown in fig. 5, one end of the second resistor is connected to the output end of the filter circuit; the other end of the second resistor is connected with one end of the third resistor and one end of the fifth resistor; the other end of the third resistor is connected with one end of the fourth resistor and the controller; the other end of the fourth resistor is grounded; the other end of the fifth resistor is connected with the LED driving circuit.
In one possible implementation, the differential feedback unit may include: a second capacitor; one end of the second capacitor is connected with the output end of the filter circuit; the other end of the second capacitor is connected with one end of the fifth resistor. In another possible implementation, the differential feedback unit includes: a second capacitor and a sixth resistor; as shown in fig. 5, one end of the sixth resistor is connected to the output end of the filter circuit; the other end of the sixth resistor is connected with one end of the second capacitor; the other end of the second capacitor is connected with one end of the fifth resistor.
Based on the display device shown in fig. 5 or fig. 6, in a possible implementation manner, the variable voltage power supply unit may include: the power supply module, the controller, the inductor and the third capacitor; the power supply module is connected with the controller; the controller is connected with one end of the inductor; the other end of the inductor is connected with one end of the third capacitor; the other end of the third capacitor is grounded. The controller is a controller in a fixed on-time COT mode, and may be a BUCK topology controller, for example.
In the embodiment of the application, the sixth resistor and the second capacitor form differential feedback, and the response speed of DC-DC is increased. However, if the capacity of the third capacitor is too large, the charge cannot be released after shutdown, the residual voltage is high, and a fixed voltage output is superimposed when the computer is started next time, so that the phenomenon of flickering of the LED light bar is caused. The difference threshold value may be set according to actual needs, and here, the value of the difference threshold value is not further limited in the embodiments of the present application.
In a possible implementation manner, the variable voltage power supply unit further includes a seventh resistor, for example, please refer to fig. 7, fig. 7 is a schematic structural diagram of another display device provided in the embodiment of the present application, and one end of the seventh resistor is connected to one end of the third capacitor; the other end of the seventh resistor is connected with the other end of the third capacitor.
It can be understood that, in the embodiment of the present application, by adding the seventh resistor, the purpose is to: when the display equipment is shut down, the seventh resistor is used for consuming a circuit in the third capacitor, so that the situation that the residual voltage of the third capacitor is high when the display equipment is shut down is avoided, and the problem that an LED lamp bar flickers when the display equipment is started can be solved.
It should be noted that the resistor according to the embodiment of the present application may be a single resistor, or may be a resistive device, or may be a module composed of multiple resistors or multiple resistive devices; the capacitor related to the embodiment of the present application may be a single capacitor, a capacitive device, or a module formed by a plurality of capacitors or a plurality of capacitive devices; the inductor according to the embodiments of the present application may be a single inductor, an inductive device, or a module composed of a plurality of inductors or a plurality of inductive devices. The embodiment of the present application is not particularly limited thereto; the field effect transistor according to the embodiment of the present application may be a single field effect transistor, a field effect device, or a module formed by a plurality of field effect transistors or a plurality of field effect devices. The embodiment of the present application is not particularly limited to this.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A display device, comprising: the LED driving circuit comprises a power supply circuit, an LED driving circuit connected with the power supply circuit, a filter circuit and a feedback circuit, wherein the filter circuit is also connected with the feedback circuit;
wherein the power supply circuit is configured to supply power to the LED driving circuit; the power supply circuit comprises a fixed voltage power supply unit and a variable voltage power supply unit, wherein the fixed voltage power supply unit is superposed on the variable voltage power supply unit to realize step power supply to the LED drive circuit;
the filter circuit is configured to filter a voltage ripple in an output voltage of the fixed voltage power supply unit;
the feedback circuit is configured to sample the output voltage of the filter circuit and feed back the variation of the output voltage to the controller of the varying voltage power supply unit;
the controller is configured to control the voltage of the variable voltage power supply unit according to the feedback of the feedback circuit.
2. The display device according to claim 1, wherein the filter circuit includes a first resistor and a first capacitor;
one end of the first resistor is connected with the output end of the fixed voltage power supply unit and the LED drive circuit respectively;
the other end of the first resistor is connected with one end of the first capacitor and the feedback circuit respectively;
the other end of the first capacitor is connected with the fixed voltage power supply unit and the variable voltage power supply unit respectively.
3. The display device according to claim 1,
the bandwidth frequency of the filter circuit is greater than the frequency of the voltage ripple in the fixed voltage power supply unit and less than the frequency of the switching ripple output by the power supply module corresponding to the fixed winding in the fixed voltage power supply unit.
4. The display device according to claim 1, wherein the feedback circuit comprises: a feedback resistance unit and a differential feedback unit;
the feedback resistance unit is respectively connected with the output end of the filter circuit, the LED drive circuit and the controller;
the differential feedback unit is respectively connected with the output end of the filter circuit and the feedback resistance unit.
5. The display device according to claim 4,
the feedback resistance unit includes: the second resistor, the third resistor, the fourth resistor and the fifth resistor;
one end of the second resistor is connected with the output end of the filter circuit;
the other end of the second resistor is connected with one end of the third resistor and one end of the fifth resistor;
the other end of the third resistor is connected with one end of the fourth resistor and the controller;
the other end of the fourth resistor is grounded;
the other end of the fifth resistor is connected with the LED driving circuit.
6. The display device according to claim 5, wherein the differential feedback unit includes: a second capacitor;
one end of the second capacitor is connected with the output end of the filter circuit;
the other end of the second capacitor is connected with one end of the fifth resistor.
7. The display device according to claim 5, wherein the differential feedback unit includes: a second capacitor and a sixth resistor;
one end of the sixth resistor is connected with the output end of the filter circuit;
the other end of the sixth resistor is connected with one end of the second capacitor;
the other end of the second capacitor is connected with one end of the fifth resistor.
8. The display device according to any one of claims 1 to 7, wherein the variable voltage power supply unit includes: the power supply module, the controller, the inductor and the third capacitor; the controller is in a fixed on-time COT mode;
the power supply module is connected with the controller;
the controller is connected with one end of the inductor;
the other end of the inductor is connected with one end of the third capacitor;
the other end of the third capacitor is grounded.
9. The display device according to claim 8, wherein the variable voltage power supply unit further comprises a seventh resistor;
one end of the seventh resistor is connected with one end of the third capacitor;
the other end of the seventh resistor is connected with the other end of the third capacitor.
10. The display device according to claim 9, wherein a capacitance value of the third capacitor is smaller than a capacitance value of the second capacitor, and a difference between the capacitance value of the third capacitor and the capacitance value of the second capacitor is smaller than a difference threshold.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010857296.4A CN111901932B (en) | 2020-08-24 | 2020-08-24 | Display device |
| PCT/CN2021/095347 WO2022041873A1 (en) | 2020-08-24 | 2021-05-21 | Display apparatus and step power circuit |
| US17/900,166 US11825577B2 (en) | 2020-08-24 | 2022-08-31 | Display apparatus and step power circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010857296.4A CN111901932B (en) | 2020-08-24 | 2020-08-24 | Display device |
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| CN111901932A true CN111901932A (en) | 2020-11-06 |
| CN111901932B CN111901932B (en) | 2022-11-29 |
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| WO2022041873A1 (en) * | 2020-08-24 | 2022-03-03 | 海信视像科技股份有限公司 | Display apparatus and step power circuit |
| WO2023109168A1 (en) * | 2021-12-14 | 2023-06-22 | 海信视像科技股份有限公司 | Display device and display control method |
| US11943853B2 (en) * | 2021-12-29 | 2024-03-26 | Shanghai Bright Power Semiconductor Co., Ltd. | Full voltage sampling circuit, driving chip, LED driving circuit and sampling method |
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| CN111901932B (en) | 2022-11-29 |
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