CN111599319B - Backlight driving circuit, method and display device - Google Patents
Backlight driving circuit, method and display device Download PDFInfo
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- CN111599319B CN111599319B CN202010484525.2A CN202010484525A CN111599319B CN 111599319 B CN111599319 B CN 111599319B CN 202010484525 A CN202010484525 A CN 202010484525A CN 111599319 B CN111599319 B CN 111599319B
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
- G09G3/3406—Control of illumination source
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
Abstract
The embodiment of the invention provides a backlight driving circuit, a method and display equipment, wherein the backlight driving circuit comprises an LED lamp, a driving controller, a switching device, an equivalent inductor, a first capacitor and a follow current device; the equivalent inductance is the equivalent inductance corresponding to the wiring between the LED lamp and the first end of the switch device; the driving controller is used for transmitting a control signal to the switching device so as to enable the switching device to be switched on or switched off under the control of the control signal; the first capacitor is used for storing energy when the switching device is switched on and providing power for the LED lamp when the switching device is switched off; and the follow current device is used for forming a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off, so that current still continuously exists on the LED lamp during the turn-off period of the switching device, namely the LED lamp can still continuously emit light during the turn-off period of the switching device, and the problem of flicker is avoided.
Description
Technical Field
The embodiment of the invention relates to the technical field of display, in particular to a backlight driving circuit, a backlight driving method and display equipment.
Background
The LED lamp is widely used as a backlight source of a liquid crystal display product due to its advantages of long life and high efficiency. The BackLight (BackLight) is a light source located at the back of the liquid crystal display product, and its light emitting effect will directly affect the visual effect of the liquid crystal display module (LCM). At present, the dimming of the backlight source continues to use a digital dimming mode of constant current + low frequency PWM (Pulse Width Modulation), that is, a power supply end outputs a fixed driving current to an LED lamp in the backlight source, and the luminance is adjusted by adjusting a time ratio of turning on and off the LED lamp in a period, so as to adjust a light emitting effect of the backlight source.
However, the inventors found that: because the LED lamp is in a light-emitting state during the starting period and is in an off state during the turning-off period, the liquid crystal display product can generate a flicker phenomenon, and the visual health of a user is influenced.
Disclosure of Invention
The embodiment of the invention provides a backlight driving circuit, a backlight driving method and display equipment, and aims to solve the problem that in the prior art, an LED lamp is turned off during the turn-off period of a switching device, so that a flicker phenomenon occurs.
In a first aspect, an embodiment of the present invention provides a backlight driving circuit, including: the LED lamp comprises an LED lamp, a driving controller, a switching device, an equivalent inductor, a first capacitor and a follow current device;
the control end of the switching device is connected with the driving controller, the first end of the switching device is connected with the power supply end sequentially through the equivalent inductor and the LED lamp, and the second end of the switching device is grounded; one end of the first capacitor is connected with the power supply end, and the other end of the first capacitor is connected with the common connecting end of the LED lamp and the switch device; one end of the follow current device is connected with the power supply end, and the other end of the follow current device is connected with the first end of the switch device; the equivalent inductor is an equivalent inductor corresponding to a wiring between the LED lamp and the first end of the switch device;
the driving controller is used for transmitting a control signal to the switching device so as to enable the switching device to be switched on or switched off under the control of the control signal;
the first capacitor is used for storing energy when the switching device is switched on and providing power for the LED lamp when the switching device is switched off;
and the follow current device is used for forming a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off.
In one possible design, the number of the LED lamps is plural, the LED lamps are connected in parallel, one end of the LED lamps connected in parallel is connected to the first end of the switching device, and the other end of the LED lamps connected in parallel is connected to the power supply end.
In one possible design, the length of the trace corresponding to each of the plurality of LED lamps is the same, where the trace corresponding to the LED is a trace between the LED lamp and the first end of the switch device.
In one possible design, the circuit further includes a feedback resistor;
and one end of the feedback resistor is connected with the second end of the switching device and the feedback end of the driving controller respectively, and the other end of the feedback resistor is grounded and is used for sampling current signals flowing through the LED lamp and sending the sampling signals to the feedback end of the driving controller.
In one possible design, the circuit further includes a second capacitor;
the cathode of the second capacitor is grounded, and the anode of the second capacitor is connected with the power supply end and used for stabilizing the power supply voltage output by the power supply end.
In a second aspect, an embodiment of the present invention further provides a backlight driving method, which is applied to the backlight driving circuit according to any one of the first aspect, and the method includes:
the driving controller transmits a control signal to the switching device so that the switching device is switched on or off under the control of the control signal;
the first capacitor stores energy when the switching device is switched on and provides power for the LED lamp when the switching device is switched off;
and the follow current device forms a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off.
In one possible design, the driving controller supplies a control signal to the switching device, including:
the driving controller transmits a control signal to the switching device based on a preset operating frequency.
In one possible design, the operating frequency is determined according to the inductance corresponding to the equivalent inductance.
In one possible design, the operating frequency is determined according to the following formula:
L＝A*[(V-Vc1)*Vc1]/(V*I*f)，
the inductance value L is the inductance value corresponding to the equivalent inductance, A is a first preset value, V is the power supply voltage output by a power supply end, Vc1 is the output voltage of the first capacitor, I is the current flowing through the LED lamp, and f is the working frequency.
In a third aspect, an embodiment of the present invention further provides a display device, including the backlight driving circuit according to any one of the first aspect.
The embodiment of the invention provides a backlight driving circuit, a method and display equipment, wherein the backlight driving circuit comprises an LED lamp, a driving controller, a switching device, an equivalent inductor, a first capacitor and a follow current device; the control end of the switching device is connected with the driving controller, the first end of the switching device is connected with the power supply end sequentially through the equivalent inductor and the LED lamp, and the second end of the switching device is grounded; one end of the first capacitor is connected with the power supply end, and the other end of the first capacitor is connected with the common connecting end of the LED lamp and the switch device; one end of the follow current device is connected with the power supply end, and the other end of the follow current device is connected with the first end of the switch device; the equivalent inductor is an equivalent inductor corresponding to a wiring between the LED lamp and the first end of the switch device; the driving controller is used for transmitting a control signal to the switching device so as to enable the switching device to be switched on or switched off under the control of the control signal; the first capacitor is used for storing energy when the switching device is switched on and providing power for the LED lamp when the switching device is switched off; and the follow current device is used for forming a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off. The first capacitor in this embodiment can store energy when the switching device is turned on, and when the switching device is turned off, the stored energy is used to provide power for the LED lamp, and the follow current device forms a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off, so that current still continuously exists on the LED lamp during the turn-off period of the switching device, that is, the LED lamp can still continue to emit light during the turn-off period of the switching device, and thus the problem of the flicker phenomenon caused by the fact that the LED lamp is turned off during the turn-off period of the switching device in the prior art can be avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a first schematic circuit diagram of a backlight driving system according to an embodiment of the present invention;
FIG. 2 is a first schematic diagram of a spike pulse according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a backlight driving circuit according to an embodiment of the invention;
FIG. 4 is a second schematic diagram of a spike pulse according to an embodiment of the present invention;
FIG. 5 is a schematic circuit diagram of an LED lamp according to an embodiment of the present invention;
fig. 6 is a first schematic circuit diagram of a backlight driving circuit according to an embodiment of the present invention;
fig. 7 is a second schematic circuit diagram of a backlight driving circuit according to an embodiment of the invention;
fig. 8 is a schematic circuit diagram of a backlight driving system according to an embodiment of the invention;
fig. 9 is a flowchart of a backlight driving method according to an embodiment of the invention.
Description of reference numerals:
a drive controller: 110;
a voltage control device: 120 of a solvent;
a freewheeling device: 130, 130;
a switching device: 140 of a solvent;
a power supply terminal: v0;
a driving chip: n1;
a first capacitance: c1;
LED lamp: VD 1;
equivalent inductance: l;
a second capacitance: c2;
a freewheeling diode: VD 2;
MOS tube: v1;
feedback resistance: r1;
resistance: r2;
GND: and (4) grounding.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
It should be understood that the following examples do not limit the order of execution of the steps of the claimed method. The various steps of the method of the invention can be performed in any possible order and in a round-robin fashion without contradicting each other.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "upper," "lower," "front," "rear," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the present invention and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting.
Furthermore, references to the description of the terms "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The technical solution of the present invention will be described in detail below with specific examples. The following several 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.
In the prior art, the dimming of the backlight source continues to use a digital dimming mode of constant current + low frequency PWM (Pulse Width Modulation), and a backlight driving system corresponding to the dimming mode is as shown in fig. 1, the system includes a backlight driving circuit 1 and a voltage control device 120, the voltage control device 120 outputs a substantially fixed power supply voltage to a power supply terminal V0, an anode of an LED lamp VD1 is connected to the power supply terminal, a cathode is connected to a drain of a MOS transistor V1, and a source of the MOS transistor V1 is grounded. The gate of the MOS transistor V1 receives the PWM signal output by the driver chip N1 through the resistor R1.
When the PWM signal is at a high level, the MOS transistor is turned on, and the LED lamp VD1 emits light by using the power supply voltage output by the voltage control device 120, and when the PWM signal is at a low level, the MOS transistor is turned off, and the LED lamp VD1 cannot emit light by using the power supply voltage output by the voltage control device 120, and is in an off state.
In addition, during the conduction period of the MOS transistor, the wiring between the LED lamp VD1 and the MOS transistor may store energy, that is, generate a harmful parasitic inductance component, and during the shutdown period of the MOS transistor, the stored energy cannot be discharged, and a spike pulse may be instantaneously induced on the MOS transistor, as shown in fig. 2 (PWM is a PWM signal output by the driver chip N1, and VDs is a voltage between the source and the drain of the MOS transistor V1).
Therefore, in order to solve the above problems, the technical idea of the present invention is to make the trace between the LED lamp VD1 and the MOS transistor V1 equivalent to an inductor, that is, the trace between the LED lamp VD1 and the MOS transistor V1 is used as an equivalent inductor L corresponding to the LED lamp VD1, and add the first capacitor C1 and the freewheeling diode on the basis of the existing multi-partition backlight driving circuit. The driving chip N1 transmits a PWM signal to the MOS transistor V1, and when the PWM signal is at a high level, the MOS transistor V1 is turned on, the LED lamp VD1 can emit light by using the power supply voltage output by the voltage control device 120, and the first capacitor C1 charges and stores energy. When the PWM signal is at a low level, the MOS transistor V1 is turned off, the first capacitor C1 discharges, and the LED lamp VD1, the equivalent inductor L, and the freewheeling diode form a freewheeling circuit, and the LED lamp VD1 can emit light by using the voltage provided by the first capacitor C1, so that the LED lamp VD1 can emit light both during the on period and the off period of the MOS transistor V1, and the problem of flicker does not occur. And during the turn-off period of the MOS transistor V1, the equivalent inductor L can discharge the energy stored in the turn-on period of the MOS transistor V1 through the freewheeling diode, so as to avoid the spike pulse instantaneously induced on the MOS transistor V1.
Fig. 3 is a schematic structural diagram of a backlight driving circuit according to an embodiment of the present invention, and as shown in fig. 3, the backlight driving circuit 2 includes an LED lamp VD1, a driving controller 110, a switching device 140, an equivalent inductor L, a first capacitor C1, and a freewheeling device 130.
The control end of the switching device 140 is connected to the driving controller 110, the first end is connected to the power supply end V0 through the equivalent inductor L and the LED lamp VD1 in sequence, and the second end is grounded. One end of the first capacitor C1 is connected with the power supply terminal V0, and the other end is connected with the common connection terminal of the LED lamp VD1 and the switching device 140. The freewheeling device 130 has one end connected to the supply terminal V0 and the other end connected to a first end of the switching device 140. The equivalent inductance L is an equivalent inductance L corresponding to a trace between the LED lamp VD1 and the first end of the switching device 140.
The driving controller 110 is configured to transmit a control signal to the switching device 140 to turn the switching device 140 on or off under the control of the control signal.
The first capacitor C1 is used for storing energy when the switching device 140 is turned on and providing power for the LED lamp VD1 when the switching device 140 is turned off.
And the freewheeling device 130 is used for forming a freewheeling loop with the equivalent inductor L and the LED lamp VD1 when the switching device 140 is turned off.
In this embodiment, the trace between the LED lamp VD1 and the first end of the switching device 140 stores energy when the switching device 140 is turned on, and the energy can be equivalent to an inductance, that is, the equivalent inductance L is the trace between the LED lamp VD1 and the first end of the switching device 140.
The driving controller 110 supplies a control signal, which is a pulse signal, to the switching device 140, the switching device 140 is turned on when the control signal is at a high level, the LED lamp VD1 may emit light by using the power supply voltage provided by the power supply terminal V0 during the period that the switching device 140 is turned on, and the first capacitor C1 stores energy during the period that the switching device 140 is turned on,
when the control signal is at a low level, the switching device 140 is turned off, and during the period that the switching device 140 is turned off, the LED lamp VD1, the equivalent inductor L and the freewheeling device 130 form a freewheeling circuit, and the first capacitor C1 supplies power to the LED lamp VD1 by using the stored energy, i.e., the LED lamp VD1 freewheels, so that the LED lamp VD1 can still emit light during the period that the switching device 140 is turned off. Since the LED lamp VD1 can emit light during both the on period and the off period of the switching device 140, the problem that the LED lamp VD1 cannot continue to emit light due to the off of the switching device 140, which causes a flicker phenomenon, does not occur.
In addition, during the on-state of the switching device 140, the equivalent inductor L stores energy, during the off-state of the switching device 140, the lower "+" upper "-" electromotive force is induced on the equivalent inductor L, the capacity stored on the equivalent inductor L can be discharged through the freewheeling device 130, when the switching device 140 is on, a spike pulse is not induced on the switching device 140 instantaneously, and the risk of breaking down the switching device 140 is avoided, as shown in fig. 4, the voltage between the source and the drain of the switching device does not spike.
Optionally, the switching device 140 is a MOS transistor, and specifically, it may be an N-type MOS transistor.
Alternatively, the driving controller 110 is a driving chip that can output a PWM signal. The freewheeling device 130 is a freewheeling diode.
Alternatively, the number of the LED lamps VD1 may be one or more, and when the number of the LED lamps VD1 is multiple, as shown in fig. 5, the multiple LED lamps VD1 are connected in parallel, one end of the parallel connected LED lamps is connected to the first end of the switching device 140, and the other end of the parallel connected LED lamps is connected to the power supply terminal V0.
The lengths of the wires corresponding to each LED lamp VD1 in the plurality of LED lamps VD1 are the same, wherein the wires corresponding to the LEDs are the wires between the LED lamp VD1 and the first end of the switch device 140.
In this embodiment, when the number of the LED lamps VD1 is plural, the plural LED lamps VD1 are connected in parallel to form a light bar, the anode of the light bar is connected to the power supply terminal V0, and the cathode of the light bar is connected to the first terminal of the switching device 140. Correspondingly, the wire between each LED lamp VD1 and the switching device 140 is taken as the equivalent inductance L corresponding to the LED lamp VD 1.
In this embodiment, the inductance value is calculated by the formula L ═ B × (ln (2S/W) + C + D × (W/S)), where L is the inductance value, B is a second predetermined value, S is the length of the trace, W is the width of the trace, C is a third predetermined value, and D is a fourth predetermined value. Since the width of the corresponding trace of each LED lamp VD1 is the same, the equivalent inductance L corresponding to each LED lamp VD1 is only related to the length of the corresponding trace.
Alternatively, B is 2, C is 0.5, and D is 0.2235.
In order to make the inductance of the equivalent inductance L corresponding to each LED lamp VD1 the same, a smaller inductance needs to be compensated, that is, a shorter length of wire needs to be compensated, so that the lengths of the wires corresponding to the LEDs are the same. For example, the light bar comprises three LED lamps, namely a first LED lamp, a second LED lamp and a third LED lamp, the first LED lamp VD1 has the longest corresponding trace length, which is Smax, and then the second LED lamp has the corresponding trace length increased so that the corresponding trace length is Smax, and the third LED lamp has the corresponding trace length increased so that the corresponding trace length is Smax, so that the first LED lamp, the second LED lamp and the third LED lamp have the same corresponding trace length.
Optionally, this embodiment further provides a display device, where the display device includes the backlight driving circuit as described above, that is, the display device performs display by using the backlight driving circuit.
As can be seen from the above description, the first capacitor C1 stores energy when the switching device 140 is turned on, and when the switching device 140 is turned off, the stored energy is used to provide power for the LED lamp VD1, and the freewheeling device 130 forms a freewheeling loop with the equivalent inductor L and the LED lamp VD1 when the switching device 140 is turned off, so that current still continues to exist on the LED lamp VD1 during the period that the switching device 140 is turned off, that is, the LED lamp VD1 can continue to emit light during the period that the switching device 140 is turned off, and thus the problem of the flicker phenomenon caused by the turn-off of the LED lamp VD1 during the period that the switching device 140 is turned off does not occur.
Fig. 6 is a first schematic circuit diagram of a backlight driving circuit according to an embodiment of the present invention, as shown in fig. 6, based on the embodiment of fig. 3, the backlight driving circuit 2 further includes a feedback resistor R1;
and one end of the feedback resistor R1 is connected to the second end of the switching device 140 and the feedback end of the driving controller 110, and the other end is grounded, and is configured to sample a current signal flowing through the LED lamp VD1 and send the sampled signal to the feedback end of the driving controller 110.
In this embodiment, during the on period of the switching device 140, the LED lamp VD1 emits light by using the power supply voltage output from the power supply terminal V0, and in order to enable the power supply terminal V0 to output a suitable power supply voltage, the driving controller 110 may sample the current signal flowing through the LED lamp VD1 through the feedback resistor R1 to obtain a corresponding current sampling signal, and send the sampling signal to the voltage control device 120, so that the voltage control device 120 adjusts the voltage output by the voltage control device according to the sampling signal, thereby outputting a suitable power supply voltage.
In addition, the amplitude of the current flowing through the LED lamp can be adjusted by adjusting the supply voltage, and the brightness can be adjusted on the basis of no flicker, so as to improve the image quality, for example, the brightness of the current display device is 100%, and the amplitude of the current flowing through the LED lamp can be reduced by reducing the supply voltage output by the voltage control device 120, so as to reduce the brightness of the display device, for example, to 5%.
The process of adjusting the output voltage of the voltage control device 120 according to the current sampling signal is an existing process, and is not described herein again.
Fig. 7 is a circuit schematic diagram of a backlight driving circuit according to an embodiment of the present invention, as shown in fig. 7, based on the embodiment of fig. 3, the backlight driving circuit 2 further includes a second capacitor C2;
the cathode of the second capacitor C2 is grounded, and the anode is connected to the power supply terminal V0, for stabilizing the power supply voltage outputted from the power supply terminal V0.
In this embodiment, the second capacitor C2 may stabilize the supply voltage outputted from the supply terminal V0, so as to stabilize the voltage signal outputted from the supply terminal V0, thereby improving the stability of the circuit.
Fig. 8 is a third circuit schematic diagram of the backlight driving system provided by the present invention, and fig. 8 illustrates a possible connection manner of the backlight driving circuit in the above embodiment, as shown in fig. 8, the backlight driving system includes a driving chip N1, a resistor R2, a MOS transistor V1, a feedback resistor R1, a first capacitor C1, an equivalent inductor L, an LED lamp VD1, a freewheeling diode VD2, a second capacitor C2, and a voltage control device.
In this embodiment, the voltage control device 120 outputs a power voltage to the power supply terminal V0, the anode of the LED lamp VD1 is connected to the power supply terminal V0, the cathode is connected to one end of the equivalent inductor L, the LED lamp VD1 is connected in parallel to the first capacitor C1, the other end of the equivalent inductor is connected to the drain of the MOS transistor V1, and the source of the MOS transistor V1 is grounded. The anode of the freewheeling diode VD2 is connected with the drain of the MOS tube V1, and the cathode is connected with the power supply end.
One end of the feedback resistor R1 is connected with the source of the MOS transistor V1 and the FB1 pin of the driving chip N1, and the other end is grounded.
The driving chip N1 is connected to the voltage control device 120 through the FB1 pin, connected to one end of the resistor R2 through the DRV pin, and connected to the other end of the resistor R2 and the gate of the MOS transistor V1.
The gate of the MOS transistor V1 receives the PWM signal output by the driver chip N1 through the resistor R1, and when the PWM signal is a high-level pulse, the MOS transistor V1 is turned on, the LED lamp VD1 emits light by using the supply voltage output by the voltage control device, and the first capacitor C1 stores energy. When the PWM signal is a low level pulse, the MOS transistor V1 is turned off, and the LED lamp VD1 cannot emit light by the supply voltage output by the voltage control device, but emits light by the voltage provided by the first capacitor C1, thereby avoiding the problem of flicker.
In addition, the equivalent inductor L stores energy during the on period of the MOS transistor V1, and the energy stored in the equivalent inductor L is discharged through the freewheeling diode during the off period of the MOS transistor V1, so that a spike pulse is not instantaneously induced in the MOS transistor V1.
Fig. 9 is a flowchart of a backlight driving method according to an embodiment of the present invention, where the method is applied to the backlight driving circuit according to the above embodiment, and as shown in fig. 9, the method of the present embodiment may include:
and S901, the driving controller transmits a control signal to the switching device so as to enable the switching device to be switched on or switched off under the control of the control signal.
S902, storing energy by a first capacitor when a switching device is switched on, and providing a power supply for the LED lamp when the switching device is switched off;
and S903, when the switching device is turned off, the follow current device, the equivalent inductor and the LED lamp form a follow current loop.
In this embodiment, the driving controller outputs a control signal to the switching device, the control signal is a pulse signal, and when the control signal is a high-level signal, the switching device is turned on, so that the LED lamp can emit light by using the power supply voltage output by the power supply terminal.
When control signal is the low level signal, the switching device cuts off, unable rethread switching device of electric current, the unable supply voltage who utilizes the feed end output of LED lamp promptly gives out light, first electric capacity discharges, for the LED lamp provides voltage, and during the switching device cuts off, the LED lamp, form the afterflow return circuit during equivalent inductance and afterflow, the LED lamp can utilize the voltage that first electric capacity provided to give out light, thereby can make LED etc. still can normally give out light during the switching device cuts off, and can not extinguish, avoid appearing the scintillation problem.
Wherein, the control signal is a PWM signal.
Alternatively, the driving controller may supply the control signal to the switching device based on a preset operating frequency, for example, 480Hz, when outputting the control signal to the switching device.
Optionally, the working frequency is determined according to the inductance corresponding to the equivalent inductance, that is, the working frequency is related to the inductance corresponding to the equivalent inductance.
Specifically, the operating frequency may be determined according to the following formula:
l ═ a [ (V-Vc1) × Vc1]/(V × I × f), where L is an inductance corresponding to the equivalent inductance, a is a first preset value, V is a supply voltage output by the power supply terminal, Vc1 is an output voltage of the first capacitor, I is a current flowing through the LED lamp, and f is an operating frequency.
In this embodiment, the inductance corresponding to the equivalent inductance, the first preset value (e.g., 5), the power supply voltage output by the power supply terminal, the output voltage of the first capacitor, and the current flowing through the LED lamp are substituted into the formula of L ═ a [ (V-Vc1) × Vc1]/(V × I × f), and the operating frequency of the driving controller is calculated.
In this embodiment, since the discontinuous control mode is prone to problems, the inductor current continuous operation mode is selected, and in order to obtain a good load regulation rate, the inductance of the equivalent inductor should be selected so that the current flowing through the equivalent inductor is kept continuous until the minimum predetermined current (for example, the rated current 1/10) is output. On the basis, the relation between the equivalent inductance corresponding to the LED lamp and the operating frequency of the driving controller can be determined as L ═ a [ (V-Vc1) × Vc1]/(V × I × f).
It can be known from the above description that the first capacitor can store energy when the switching device is turned on, and when the switching device is turned off, the stored energy is used to provide power for the LED lamp, and the freewheeling device forms a freewheeling loop with the equivalent inductor and the LED lamp when the switching device is turned off, so that current still continuously exists on the LED lamp during the period when the switching device is turned off, that is, the LED lamp can still continuously emit light during the period when the switching device is turned off, thereby avoiding the problem that the flickering phenomenon occurs due to the fact that the LED lamp is turned off during the period when the switching device is turned off.
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 backlight driving circuit, comprising: the LED lamp comprises an LED lamp, a driving controller, a switching device, an equivalent inductor, a first capacitor and a follow current device;
the control end of the switching device is connected with the driving controller, the first end of the switching device is connected with the power supply end sequentially through the equivalent inductor and the LED lamp, and the second end of the switching device is grounded; one end of the first capacitor is connected with the power supply end, and the other end of the first capacitor is connected with the common connecting end of the LED lamp and the switch device; one end of the follow current device is connected with the power supply end, and the other end of the follow current device is connected with the first end of the switch device; the equivalent inductor is an equivalent inductor corresponding to a wiring between the LED lamp and the first end of the switch device;
the driving controller is used for transmitting a control signal to the switching device so as to enable the switching device to be switched on or switched off under the control of the control signal;
the first capacitor is used for storing energy when the switching device is switched on and providing power for the LED lamp when the switching device is switched off;
and the follow current device is used for forming a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off so that the equivalent inductor discharges the energy stored when the switching device is turned on through the follow current device.
2. The backlight driving circuit according to claim 1, wherein the number of the LED lamps is plural, the plural LED lamps are connected in parallel, one end of the parallel LED lamps is connected to the first end of the switching device, and the other end of the parallel LED lamps is connected to the power supply terminal.
3. The backlight driving circuit according to claim 2, wherein the length of the corresponding trace of each of the plurality of LED lamps is the same, wherein the corresponding trace of the LED is a trace between the LED lamp and the first end of the switch device.
4. The backlight driving circuit according to claim 1, wherein the circuit further comprises a feedback resistor;
and one end of the feedback resistor is connected with the second end of the switching device and the feedback end of the driving controller respectively, and the other end of the feedback resistor is grounded and is used for sampling current signals flowing through the LED lamp and sending the sampling signals to the feedback end of the driving controller.
5. The backlight driving circuit according to any one of claims 1 to 4, wherein the circuit further comprises a second capacitor;
the cathode of the second capacitor is grounded, and the anode of the second capacitor is connected with the power supply end and used for stabilizing the power supply voltage output by the power supply end.
6. A backlight driving method applied to the backlight driving circuit according to any one of claims 1 to 5, the method comprising:
the driving controller transmits a control signal to the switching device so that the switching device is switched on or off under the control of the control signal;
the first capacitor stores energy when the switching device is switched on and provides power for the LED lamp when the switching device is switched off;
and the follow current device forms a follow current loop with the equivalent inductor and the LED lamp when the switching device is turned off.
7. The method of claim 6, wherein driving the controller to deliver the control signal to the switching device comprises:
the driving controller transmits a control signal to the switching device based on a preset operating frequency.
8. The method of claim 7, wherein the operating frequency is determined based on an inductance corresponding to an equivalent inductance.
9. The method of claim 8, wherein the operating frequency is determined according to the following equation:
L＝A*[(V-Vc1)*Vc1]/(V*I*f)，
the inductor comprises an equivalent inductor, a power supply end, a Vc1, a power supply end, a power supply voltage, a current I, and a working frequency f, wherein L is the inductance corresponding to the equivalent inductor, A is a first preset value, V is the power supply voltage output by the power supply end, Vc1 is the.
10. A display device characterized by comprising the backlight driving circuit according to any one of claims 1 to 5.
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| CN202110728312.4A CN113257199B (en) | 2020-06-01 | 2020-06-01 | Backlight driving circuit, method and display device |
| CN202010484525.2A CN111599319B (en) | 2020-06-01 | 2020-06-01 | Backlight driving circuit, method and display device |
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| CN202010484525.2A CN111599319B (en) | 2020-06-01 | 2020-06-01 | Backlight driving circuit, method and display device |
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| CN112270150A (en) * | 2020-11-06 | 2021-01-26 | 成都海光集成电路设计有限公司 | Method and device for calculating transmission line parasitic parameters on packaging substrate |
| CN113628594B (en) * | 2021-09-26 | 2022-12-02 | 合肥鑫晟光电科技有限公司 | Light-emitting substrate, driving method thereof and display device |
| CN114596821B (en) * | 2022-05-09 | 2022-08-16 | 惠科股份有限公司 | Control circuit, control method and display device |
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| CN113257199B (en) | 2022-07-08 |
| CN111599319A (en) | 2020-08-28 |
| CN113257199A (en) | 2021-08-13 |
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