CN101409044B - Backlight assembly and driving method thereof - Google Patents

Abstract

The invention discloses a backlight assembly and a driving method thereof. The backlight assembly comprises a light emitting diode driving circuit, a direct current power converter and a feedback compensation circuit. The light emitting diode driving circuit comprises a plurality of light emitting elements and a plurality of dimming circuits. The backlight assembly divides a plurality of temperature distribution areas according to the relative relation of the heat dissipation directions, and a first light emitting element is arranged in the lowest temperature area. The first light emitting element is coupled with the first dimming circuit to generate a first feedback signal. The feedback compensation circuit receives the first feedback signal and generates a voltage compensation signal. The DC power converter receives the voltage compensation signal, operates according to the voltage compensation signal, and provides and outputs a working voltage to the LED driving circuit. Therefore, the invention can reduce the number of feedback signals and the complexity of processing the feedback signals, and improve the system efficiency.

Description

Backlight assembly and driving method thereof

technical field

The present invention relates to a backlight assembly and its driving method, and in particular to a light emitting diode (Light emitting diode, LED) backlight assembly and its driving method.

Background technique

In recent years, the backlight components of liquid crystal displays mostly use light emitting diodes (Light Emitting Diode, LED) which have the characteristics of long life, high efficiency and low environmental pollution as the backlight. As the liquid crystal panel of the liquid crystal display becomes larger and larger, its backlight assembly also uses more light-emitting diodes to provide sufficient backlight. Therefore, the circuits driving the LEDs will generate more power consumption. Please refer to FIG. 1 . FIG. 1 is a temperature distribution diagram of the backplane 10 of the LED backlight mechanism in thermal equilibrium. Since the backplane of the LED backlight mechanism of a liquid crystal display in general use is roughly perpendicular to the desktop (or horizontal plane), in a state of thermal equilibrium, the heat generated by the backlight assembly makes the temperature distribution of the mechanism backplane from bottom to top as follows: From low temperature to high temperature.

Please refer to FIG. 2 . FIG. 2 is a graph showing the relative relationship between forward conduction current, forward conduction voltage and ambient temperature of an LED. Figure 2 draws 3 forward conduction current curves, one of which is chosen randomly: when the forward conduction current IFP of the same LED increases in temperature, the forward conduction voltage of the LED will decrease as the temperature rises.

Please refer to FIG. 3 , which is a circuit diagram of a conventional backlight assembly. The backlight assembly 300 includes N sets of LED driving circuits: the light emitting elements 301 to 30N are respectively coupled to the corresponding dimming circuits 331 to 33N. Since the heat generated by the backlight assembly is in a thermal equilibrium state, the temperature of the backplane of the LED backlight mechanism will show different changes, so that the ambient temperature of each light-emitting element is not the same, and its brightness is also different, which is easy to cause display problems. bad. Therefore, in the traditional design of the backlight assembly 300 , N feedback signals Vm1 to VmN are obtained from N sets of LED driving circuits for closed-loop driving control, and then the output of the DC power converter 310 is adjusted. However, the complexity of designing the feedback compensation circuit 320 to process the N feedback signals Vm1 to VmN is quite high, and designing N feedback signals will increase the difficulty of circuit wiring, so the circuit cost of the backlight assembly 300 will also increase relatively.

Contents of the invention

The purpose of the present invention is to provide a backlight assembly, which can use a small number of feedback signals for closed-loop control, can reduce the complexity of designing feedback compensation circuits, can also reduce the difficulty of circuit wiring, and reduce the circuit complexity of the backlight assembly. cost.

The present invention also provides a driving method for a backlight assembly. When adjusting the working voltage of a DC power converter, fewer feedback signals can be used for closed-loop control, the temperature of the backlight assembly can be lowered to reduce power consumption, and the light emission can be improved. The life of the diode can be improved, so the circuit performance of the backlight component can be improved.

The present invention proposes a backlight assembly, which forms a plurality of temperature distribution regions according to the relative relationship of heat dissipation directions, and one of these temperature distribution regions is the lowest temperature region. The backlight assembly includes a light emitting diode driving circuit, a DC power converter and feedback compensation circuit. The LED driving circuit is used to provide the backlight source and generate the first feedback signal. The LED driving circuit includes a plurality of light emitting elements and a plurality of dimming circuits. The light-emitting elements are used to receive the working voltage to generate the backlight, and the first light-emitting element of the light-emitting elements is arranged in the lowest temperature area. The dimming circuits are used to provide the driving current of the light-emitting elements, each dimming circuit is coupled to one of the corresponding light-emitting elements, and the first feedback signal is from the dimming corresponding to the first light-emitting element The coupling of the first dimming circuit of the circuit is obtained. The DC power converter is coupled to the LED driving circuit, and adjusts and outputs the working voltage according to the voltage compensation signal. The feedback compensation circuit is coupled between the DC power converter and the LED driving circuit for receiving the first feedback signal to generate a voltage compensation signal.

In one embodiment of the above backlight assembly, the feedback compensation circuit includes a first error amplifier and a first voltage compensator. The first error amplifier receives the first reference signal and the first feedback signal, and compares the first reference signal with the first feedback signal to obtain an output. The first voltage compensator is coupled between the output terminal of the first error amplifier and the DC power converter, and generates and outputs a voltage compensation signal accordingly.

In another embodiment of the above-mentioned backlight assembly, a second light-emitting element of the light-emitting elements is arranged in the region with the lowest temperature, and the light-emitting diode drive circuit also generates a second feedback signal, and the second feedback signal is from the second light-emitting element A coupling of a second dimming circuit of the dimming circuits corresponding to the components is obtained. The feedback compensation circuit also receives the second feedback signal, and generates a voltage compensation signal according to the average value of the first feedback signal and the second feedback signal.

From another point of view, the present invention further proposes a driving method of a backlight assembly. The backlight assembly includes a light emitting diode drive circuit, a DC power converter and a feedback compensation circuit. The light emitting diode drive circuit includes a plurality of light emitting elements and a plurality of dimming circuits. The driving method includes the following steps: the backlight assembly divides a plurality of temperature distribution areas according to the relative relationship of heat dissipation directions, and one of the temperature distribution areas is the lowest temperature area; the LED driving circuit generates a first feedback signal, and the first feedback signal It is obtained from the coupling of the first dimming circuit corresponding to the first light-emitting element of these light-emitting elements, and the first light-emitting element is arranged in the lowest temperature region; the feedback compensation circuit receives the first feedback signal , and generate a voltage compensation signal; the DC power converter receives the voltage compensation signal, and operates, provides and outputs an operating voltage to the LED driving circuit according to the voltage compensation signal.

In the driving method of the above-mentioned backlight assembly, in an embodiment, the feedback compensation circuit is coupled between the DC power converter and the LED driving circuit, and is used for receiving the first feedback signal to generate a voltage compensation signal.

In another embodiment, the method for driving the above-mentioned backlight assembly further includes the following steps. The light-emitting diode drive circuit generates a second feedback signal, and the second feedback signal is obtained from the coupling of the second light-emitting element of the light-emitting elements corresponding to the second light-adjusting circuit of the light-emitting element, and the second light-emitting element It is configured in the lowest temperature area. The feedback compensation circuit receives the second feedback signal, and generates a voltage compensation signal according to the average value of the first feedback signal and the second feedback signal.

The backlight assembly of the present invention is divided into multiple temperature distribution areas according to heat dissipation. The feedback compensation circuit of the backlight assembly extracts the feedback signal from the lowest temperature area for processing, and generates a compensation voltage for the DC power converter to adjust the operating voltage, thus simplifying feedback. The compensation circuit receives the number of feedback signals instead of sending more feedback signals to the feedback compensation circuit. Therefore, the present invention can reduce the number of feedback signals between the feedback compensation circuit and the LED driving circuit. The backlight assembly and its driving method of the present invention can reduce the complexity of designing the feedback compensation circuit, reduce the difficulty of circuit wiring, reduce the circuit cost of the backlight assembly, reduce the power consumption of the backlight assembly, reduce the temperature of the light-emitting diode backlight assembly, and improve the light emission. The lifetime of the diode can be improved, and the circuit performance of the entire backlight assembly can be improved.

In order to make the above and other objects, features and advantages of the present invention more comprehensible, the embodiments of the present invention are exemplified below and described in detail with accompanying drawings.

Description of drawings

FIG. 1 is a temperature distribution diagram of a backplane of an LED backlight mechanism at thermal equilibrium.

Fig. 2 is a graph showing the relative relationship between forward conduction current, forward conduction voltage and ambient temperature of LED.

FIG. 3 is a circuit diagram of a conventional backlight assembly.

FIG. 4( a ) is a diagram showing multiple temperature distribution regions divided by the backplane of the LED backlight mechanism according to an embodiment of the present invention.

FIG. 4( b ) is a circuit diagram of a backlight assembly according to multiple temperature distribution regions in FIG. 4( a ).

FIG. 4( c ) is a relative relationship diagram between the backlight element of the backlight assembly of FIG. 4( b ) and the backplane of the LED backlight mechanism.

Figure 4(d) is an analysis of the open-loop control architecture diagram of Figure 4(b).

Figure 4(e) is the electrical characteristic diagram of the cooling and heating machine when simulating the open loop control.

Figure 4(f) is the architecture diagram of the simulated closed-loop control.

Fig. 4(g) is a comparative diagram of various voltages for feedback compensation for regions with high temperature and regions with low temperature respectively.

FIG. 5( a ) to FIG. 5( c ) are temperature distribution area diagrams according to another embodiment of the present invention.

FIG. 5( d ) is a circuit diagram of a backlight assembly according to another embodiment of the present invention.

Detailed ways

The inventor of the present invention considers that the circuit design of the traditional backlight assembly is quite complex, and came up with the present invention after analyzing and simulating various situations. One of the main features of the present invention is to extract the feedback signal from the lowest temperature region for processing. The various embodiments of the present invention will be described below.

Please refer to FIG. 4( a ). FIG. 4( a ) is a diagram showing a plurality of temperature distribution regions divided by the backplane of a light emitting diode (Lightemitting diode, LED) backlight mechanism according to an embodiment of the present invention. In order to reduce the complexity, N feedback signals Vm1 to VmN are traditionally required, but in the embodiment of the present invention, the feedback signals required by the conventional technology are reduced. Firstly, the backlight assembly forms a plurality of temperature distribution regions according to the relative relationship of heat dissipation directions. In FIG. 4( a ), the backlight assembly is arranged on the backplane 40 of the LED backlight mechanism, and the backplane 40 of the LED backlight mechanism is divided into three temperature distribution areas, which are respectively T1 area, T2 area and T3 area. Those who have ordinary knowledge of this technology should be able to understand that the division of temperature distribution areas can be divided in advance according to heat balance simulation or experimental results, so the number of divided temperature distribution areas is not limited. Assuming a general situation, the backplane 40 of the LED backlight mechanism is standing upright on the desktop, and the backplane 40 of the LED backlight mechanism has small heat dissipation holes around or only the uppermost one has small heat dissipation holes. Therefore, when the liquid crystal display in use is in thermal equilibrium, the LED backlight mechanism backplane 40 will be the hottest in the T1 area, followed by the T2 area, and the T3 area has the lowest temperature area. When designing a backlight assembly, the LEDs located in each area are exposed to different ambient temperatures, so the forward voltage of the LEDs in each area will be different. The forward conduction voltage of the LED in the T1 area is the smallest, the forward conduction voltage of the LED in the T3 area is the largest, and the forward conduction voltage of the LED in the T2 area is the second largest.

Based on the above, after dividing a number of temperature regions, the number of feedback signals must be reduced. The way to reduce the number of feedback signals is to extract feedback signals from a certain area, so that the complexity of processing feedback signals will be greatly reduced. To verify that it is feasible, please refer to Figure 4(b) and perform the following experiments. FIG. 4( b ) is a circuit diagram of a backlight assembly according to multiple temperature distribution regions in FIG. 4( a ). The backlight assembly 42 includes light-emitting elements in a T1 area, a light-emitting element in a T2 area, and a light-emitting element in a T3 area. Wherein, the light-emitting elements in the T1 area include light-emitting elements 41a, 41b..., the light-emitting elements in the T2 area include light-emitting elements 43a, 43b..., the light-emitting elements in the T3 area include light-emitting elements 45a, 45b..., and each light-emitting element includes at least one light-emitting diode.

In order to analyze the various situations of the backlight assembly 42 in the T1 area to the T3 area: when the first case is a cold machine, the open-loop control is simulated; when the second case is a hot machine, the open-loop control of the T1 area is simulated; the third case Simulate the open-loop control of the T3 zone when the situation is a hot engine. For the distribution of each light-emitting element in FIG. 4(b) on the backplane 40 of the LED backlight mechanism in FIG. 4(a), reference may be made to FIG. 4(c). FIG. 4( c ) is a relative relationship diagram between the backlight elements of the backlight assembly 42 and the backplane of the LED backlight mechanism.

Here, for the analysis of the above-mentioned various situations, it is assumed that the light-emitting elements 41a-41c, 43a-43c, 45a-45c use the same LED and the same number of light-emitting elements, and the LEDs are connected in series. Please refer to Figure 4(d). Figure 4(d) is an analysis of the open-loop control architecture diagram of Figure 4(b). The DC power converter 48a generates the operating voltage VLED to drive the light emitting element 46, that is, the driving power for lighting the light emitting diodes LED1-LEDN. The sum of the forward conduction voltages (Vf ₁ , Vf ₂ , . . . , Vf _N ) of each light emitting diode is the forward conduction voltage Vf_total of the light emitting element 46 . The dimming circuit 47 includes a switch SW and a constant current source I1. The voltage Vm is generated from the coupling between the light emitting element 46 and the dimming circuit 47 , and the relationship is VLED=Vf_total+Vm. (Assume that the light-emitting element 46 currently uses 4 light-emitting diodes, and the forward conduction voltage of each light-emitting diode is equal to 2V.)

When the first case is a cold machine, the open-loop control is simulated, so the working voltage VLED is fixed. A data is provided here. When the constant current source I1 is 20mA and the working voltage VLED is 9V, the forward conduction voltage Vf_total is 8V, the voltage Vm is 1V, and the power consumed by Vm is 20mV.

Next, when the second case is a hot engine, the open-loop control in the T1 area is simulated. A data is provided here. When the constant current source I1 is 20mA and the working voltage VLED is 9V, the forward conduction voltage Vf_total is 6.8V, the voltage Vm is 2.2V, and the Vm consumption power is 44mV. Therefore, the forward conduction voltage of each LED drops to 0.3V.

When the third case is a hot engine, the open-loop control of T3 zone is simulated. A data is provided here. When the constant current source I1 is 20mA and the working voltage VLED is 9V, the forward conduction voltage Vf_total is 7.6V, the voltage Vm is 1.4V, and the Vm power consumption is 28mV. Therefore, the forward conduction voltage of each LED drops to 0.1V.

For the above three simulation situations, please refer to Figure 4(e) after sorting out the data. Therefore, it is known that the forward conduction voltage Vf_total of the light-emitting element 46 decreases and the voltage Vm increases due to the increase of the system temperature, which increases the power consumption of the switch SW, increases the power loss, and deteriorates the element efficiency.

Next, simulate the fourth and fifth situations. The fourth case is when the engine is warming up, and the feedback signal from the T1 area is simulated for closed-loop control; the fifth case is when the engine is warming up, the feedback signal from the T3 area is simulated for closed-loop control. Among them, in the fourth and fifth cases, feedback control is only performed on one temperature distribution area, and no feedback control is performed on the other two areas. In the fourth case, the feedback signal Vm1a or Vm1b or the average value of the feedback signals Vm1a and Vm1b is obtained. In the fifth case, the feedback signal Vm3a or Vm3b is obtained or the average value of the feedback signals Vm3a and Vm3b is obtained.

Please refer to FIG. 4(f). FIG. 4(f) is an analysis of FIG. 4(b), a structure diagram of a closed-loop control when simulating a heat engine. The voltage Vm originally in FIG. 4(d) now becomes a feedback signal in FIG. 4(f). The light emitting element 46 uses 4 identical light emitting diodes. The feedback compensation circuit 49 includes an error amplifier 49b and a voltage compensator 49a, and the voltage compensator 49a is coupled between the error amplifier 49b and the DC power converter 48b. The error amplifier 49b receives the feedback signal Vm and a reference signal Vref, and the voltage compensator 49a generates a voltage compensation signal 49c to the DC power converter 48b. The DC power converter 48b adjusts and outputs the working voltage VLED according to the voltage compensation signal 49c. In the fourth case when the engine is hot, the feedback signal from the T1 area is simulated for closed-loop control, and a data file is provided here. When the constant current source I1 is 20mA and the original operating voltage VLED is 9V, the work after compensation The voltage VLED is 7.8V. The forward conduction voltage Vf_total of the T1 area is 6.8V, so the voltage Vm of the T1 area is 1V, but the forward conduction voltage Vf_total of the T3 area is 7.6V, so the operating voltage of the light-emitting element in the lower temperature area (T3 area) Insufficient, making the LED unstable.

Next, when the fifth case is a hot engine, simulate and capture the feedback signal in the T3 area for closed-loop control, and provide a data file here. When the constant current source I1 is 20mA and the original operating voltage VLED is 9V, after compensation The operating voltage VLED is 8.6V. The forward conduction voltage Vf_total of the T3 area is 7.6V, so the voltage Vm of the T3 area is 1.0V; while the forward conduction voltage Vf_total of the T1 area is 6.8V, and the voltage Vm of the T1 area is 1.8V. Therefore, when the working voltage VLED is adjusted down to 8.6V, the driving circuit of the backlight assembly 42 in FIG. 4( b ) can be covered. For the simulation of the fourth and fifth cases above, please refer to Figure 4(g) after sorting out the data, where the area with higher temperature is used as feedback compensation, the sequence between the adjusted operating voltage VLED and the area with lower temperature If the voltage difference between the conduction voltage Vf_total is too small, the working efficiency of the light-emitting element may be unstable. It is proved that the backlight assembly and its driving method of the present invention adopt the feedback signal of the region with the lowest temperature (T3 region in this embodiment), and the adjustment result does achieve the desired effect. Therefore, it is feasible to extract the feedback signal from the "lowest temperature area" (T3 area). In this embodiment, the complexity of processing the feedback signal by the feedback compensation circuit can be reduced to less than one-third.

Please refer to Figure 5(a). FIG. 5( a ) is a diagram of the temperature distribution area according to another embodiment of the present invention. We divide the backplane 50 of the LED backlight mechanism into nine areas, such as areas A1 to A3, areas B1 to B3, and areas C1 to C3 as shown in the figure. Assuming a general situation, the backplane 50 of the LED backlight mechanism is upright on the desktop, and there are small heat dissipation holes around the backplane 50 of the LED backlight mechanism or only the uppermost one. Therefore, the temperature in the area A1 to A3 is the highest, the temperature in the area B1 to B3 is the second highest, and the temperature in the area C1 to C3 will be the lowest. According to the temperature distribution of the backplane 50 of the LED backlight mechanism, the backlight assembly can take an extraction point of the light-emitting elements arranged in one of the areas C1 to C3 from one of the areas C1 to C3 for feedback control. Feedback signal to adjust the common working voltage of all light emitting elements. Of course, those with ordinary knowledge of this technology should be able to understand that the average value of a plurality of acquisition points can also be taken from areas C1 to C3 for feedback control. Without departing from the spirit and scope of the present invention, the present invention The scope of protection should not be limited to what is disclosed in the examples.

Please refer to Figure 5(b). FIG. 5( b ) is a diagram of the temperature distribution area according to another embodiment of the present invention. We divide the backplane 50 of the LED backlight mechanism into nine areas, such as A1-A3, B1-B3, and C1-C3 in Figure 5(a), but here the backplanes of C1 and C3 Additional cooling fins are installed on it. Therefore, in thermal equilibrium, the temperatures of C1 and C3 are the lowest. The backlight assembly can take a pick-up point of the light-emitting elements arranged in the area C1 and C3 for feedback control, and then adjust the common work of all the light-emitting elements according to the average value of the feedback signals of the two pick-up points voltage; or only pick up a pick-up point of the light-emitting elements in the C1 area or the C3 area for feedback control, and then adjust the common working voltage of all the light-emitting elements.

Please refer to Figure 5(c). FIG. 5( c ) is a diagram of the temperature distribution area according to another embodiment of the present invention. This is similar to the method shown in FIG. 5( b ). In the same way, fans are installed in the C1 and C3 regions of the backplane 50 of the LED backlight mechanism, so that the temperatures in the C1 and C3 regions are the lowest during heat balance. Therefore, the backlight assembly can take a pick-up point of the light-emitting elements arranged in the region C1 and C3 for feedback control, and then adjust the brightness of all the light-emitting elements according to the average value of the feedback signals of the two pick-up points. The common working voltage; or only pick up a pick-up point of the light-emitting elements in the C1 region or the C3 region for feedback control, and then adjust the common working voltage of all the light-emitting elements.

Through the description of Figure 5(b) and Figure 5(c), those with ordinary knowledge of this technology should be able to understand that heat sinks or fans are used to ensure that C1 and C3 are the lowest temperature areas. Of course, water cooling devices or other heat dissipation devices can also be used method to achieve. The lowest temperature area is relative to the thermal design of the backplane. When considering the symmetry of the average heat dissipation, the area with the lowest temperature can be located on each side of the backplane. In addition, there is no limit to the number of divided temperature regions and the number of cooling devices used, and there are many combinations of the number of divided temperature regions and the number of used cooling devices. Therefore, without departing from the spirit and scope of the present invention, the protection scope of the present invention should not be limited to the disclosed embodiments.

Please refer to Figure 5(d). FIG. 5( d ) is a circuit diagram of a backlight assembly according to another embodiment of the present invention. The backlight assembly 500 is configured on the backplane 50 of the LED backlight mechanism with a heat dissipation device as shown in FIG. 5( b ) or FIG. 5( c ). The backlight assembly 500 forms multiple temperature distribution regions according to the relative relationship of heat dissipation directions, as shown in FIG. 5( a ). The focus of the present invention is to extract the feedback signal from the "lowest temperature area", as shown in Figure 5 (a) and Figure 5 (d): the C1 area and the C3 area are the lowest temperature areas, and the first signal is extracted from the C1 area and C3 The feedback signal Vmc1 and the second feedback signal Vmc3 are used for closed-loop control.

The backlight assembly 500 includes a LED driving circuit 52 , a DC power converter 51 and a feedback compensation circuit 55 . The LED driving circuit 52 is coupled between the DC power converter 51 and the feedback compensation circuit 55 . The LED driving circuit 52 includes a plurality of light emitting elements and a plurality of dimming circuits. Each light-emitting element includes at least one light-emitting diode, and the forward voltage characteristic of the light-emitting diode will be affected by the ambient temperature. Each dimming circuit includes a switch SW and a constant current source I, wherein one end of the switch SW is coupled to one of the corresponding light-emitting elements, the other end of the switch SW is coupled to the corresponding constant current source I, and the corresponding The other end of the constant current source I is grounded.

Each dimming circuit can provide the driving current of its corresponding light-emitting element, and the light-emitting element can generate a backlight after receiving the working voltage VLED, and the first light-emitting element 510 and the second light-emitting element 511 of these light-emitting elements are configured at the lowest temperature area, and the area with the lowest temperature is also equipped with a cooling device. The first feedback signal Vmc1 is obtained from the coupling of the first dimming circuit 512 of the dimming circuits corresponding to the first light emitting element 510. The second feedback signal is obtained from a coupling of a second dimming circuit 514 of the dimming circuits corresponding to the second light emitting element 511 . Therefore, the LED driving circuit 52 also generates the first feedback signal Vmc1 and the second feedback signal Vmc3 .

The feedback compensation circuit 55 includes an error amplifier 59 and a voltage compensator 57 . The error amplifier 59 receives the reference signal Vref, the first feedback signal Vmc1 and the second feedback signal Vmc3 , and compares the average value of the reference signal Vref, the first feedback signal Vmc1 and the second feedback signal Vmc3 to obtain an output. Wherein, in order to avoid inaccurate feedback signals, the average value of the two feedback signals can be used for comparison with the reference signal Vref, of course, only the first or second feedback signal can be used to compare the reference signal Vref. The voltage compensator 57 is coupled between the output of the error amplifier 59 and the DC power converter 51 , and generates and outputs a voltage compensation signal 53 accordingly.

The DC power converter 51 can adjust the input and output of the power with different DC levels according to the voltage compensation signal 53 in a pulse width modulation manner, and output a working voltage VLED. The type of the DC power converter 51 can be a traditional step-up DC power converter, a step-down DC power converter or a buck-boost DC power converter, which will not be repeated here.

Let's compare the difference between Fig. 3 and Fig. 5(d). In the conventional technology, the backlight assembly 300 of Fig. 3 uses a relatively large number of feedback signals. In the backlight assembly 300 with a heavy number of feedback signals, the traditional feedback compensation circuit The 320 will be overloaded accordingly. In the backlight assembly 500 of FIG. 5( d ), the structure of the feedback compensation circuit 55 is relatively simple, and the number of feedback signals processed by the feedback compensation circuit 55 is very small compared with the feedback compensation circuit 320 . Therefore, the reduced number of feedback signals in the embodiment of the present invention can reduce the complexity of designing the feedback compensation circuit 55 and also reduce the difficulty of circuit wiring, and the circuit cost of the backlight assembly 500 is also reduced compared with the backlight assembly 300 .

In addition to the backlight assembly of the above embodiments, the present invention also includes a corresponding driving method of the backlight assembly. Those who have ordinary knowledge in the related technical fields of the present invention should be able to implement the driving method of the backlight assembly of the present invention through the foregoing embodiments of the backlight assembly, so details will not be repeated.

To sum up the above, the present invention simplifies the number of feedback signals received by the feedback compensation circuit, and the backlight assembly adopts the closed-loop control by extracting feedback signals from the "lowest temperature area" instead of sending a considerable number of feedback signals to the feedback compensation circuit. Therefore, the present invention can reduce the number and lines of feedback signals between the feedback compensation circuit and the LED driving circuit. The backlight assembly and its driving method of the present invention have at least the following advantages:

1. Use fewer feedback signals for closed-loop control;

2. Reduce the complexity of designing feedback compensation circuits;

3. Reduce the difficulty of circuit wiring;

4. Reduce the circuit cost of backlight components;

5. Reduce the power consumption of backlight components;

6. Reduce the temperature of LED backlight components;

7 Improve the life of light-emitting diodes;

8. Significantly improve the circuit performance of the backlight component.

Although the present invention has been disclosed above with the embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. Therefore The scope of protection of the present invention should be defined by the claims.

Claims (22)

1. A backlight assembly, which forms a plurality of temperature distribution regions according to the relative relationship of heat dissipation directions, one of these temperature distribution regions is a region with the lowest temperature, and the backlight assembly includes: A light-emitting diode drive circuit, used to provide backlight and generate a first feedback signal, the light-emitting diode drive circuit includes: A plurality of light-emitting elements are used to receive an operating voltage to generate a backlight, and a first light-emitting element of the light-emitting elements is arranged in the lowest temperature region; and A plurality of dimming circuits are used to provide the driving current of the light-emitting elements, each of the dimming circuits is coupled to a corresponding one of the light-emitting elements, and the first feedback signal is from the corresponding one of the first light-emitting elements obtained by coupling a first dimming circuit of the dimming circuits; a DC power converter, coupled to the LED drive circuit, and adjusts and outputs the operating voltage according to a voltage compensation signal; and A feedback compensation circuit, coupled between the DC power converter and the LED driving circuit, is used to receive the first feedback signal and generate the voltage compensation signal accordingly. 2. The backlight assembly according to claim 1, wherein the feedback compensation circuit comprises: a first error amplifier, receiving a first reference signal and the first feedback signal, and comparing the first reference signal and the first feedback signal to obtain an output; and A first voltage compensator is coupled between the output of the first error amplifier and the DC power converter, and generates and outputs the voltage compensation signal accordingly. 3. The backlight assembly according to claim 1, wherein a cooling device is disposed in the lowest temperature area, wherein the cooling device is a heat sink, a fan or a water cooling device. 4. The backlight assembly as claimed in claim 1, wherein among the light emitting elements, each light emitting element comprises at least one light emitting diode. 5. The backlight assembly according to claim 1, wherein, among the dimming circuits, each dimming circuit comprises: a switch, one end of which is coupled to a corresponding one of the light-emitting elements; and A certain current source is coupled between the switch and ground. 6. The backlight assembly according to claim 1, wherein a second light-emitting element of the light-emitting elements is disposed in the region with the lowest temperature, and the light-emitting diode driving circuit also generates a second feedback signal, and the first The two feedback signals are obtained from a coupling of a second dimming circuit of the dimming circuits corresponding to the second light emitting element. 7. The backlight assembly according to claim 6, wherein the feedback compensation circuit further receives the second feedback signal, and generates the voltage compensation signal according to the average value of the first feedback signal and the second feedback signal . 8. The backlight assembly according to claim 6, wherein the feedback compensation circuit comprises: a second error amplifier, receiving a second reference signal, the first feedback signal and the second feedback signal, and comparing the average value of the first reference signal, the first feedback signal and the second feedback signal to obtain an output ;as well as A second voltage compensator is coupled between the output of the second error amplifier and the DC power converter, and generates and outputs the voltage compensation signal accordingly. 9. The backlight assembly as claimed in claim 1, wherein the DC power converter adjusts the operating voltage in a pulse width modulation manner. 10. The backlight assembly according to claim 1, wherein the DC power converter is a boost DC power converter, a buck DC power converter or a buck-boost DC power converter. 11. A method for driving a backlight assembly, the backlight assembly comprising a light-emitting diode drive circuit, a DC power converter and a feedback compensation circuit, the light-emitting diode drive circuit comprising a plurality of light-emitting elements and a plurality of dimming circuits, the drive Methods include: a. The backlight assembly is divided into a plurality of temperature distribution regions according to the relative relationship of heat dissipation directions, and one of the temperature distribution regions is a region with the lowest temperature; b. The light-emitting diode drive circuit generates a first feedback signal, and the first feedback signal is from a coupling of a first light-adjusting circuit of the light-emitting elements corresponding to a first light-emitting element of the light-emitting elements to obtain, and the first light-emitting element is configured in the lowest temperature region; c. the feedback compensation circuit receives the first feedback signal and generates a voltage compensation signal; and d. The DC power converter receives the voltage compensation signal, operates according to the voltage compensation signal, and provides and outputs a working voltage to the LED driving circuit. 12. The driving method of a backlight assembly according to claim 11, wherein the light-emitting elements receive the operating voltage to generate a backlight, and the dimming circuits are coupled to the light-emitting elements, and each dimming The light circuit is coupled to a corresponding one of the light-emitting elements, and the dimming circuits are used to provide driving current for the light-emitting elements. 13. The driving method of a backlight assembly according to claim 11, wherein the feedback compensation circuit is coupled between the DC power converter and the LED driving circuit to receive the first feedback signal, according to to generate the voltage compensation signal. 14. The driving method of the backlight assembly according to claim 11, wherein the DC power converter is coupled to the LED driving circuit, and adjusts and outputs the operating voltage according to the voltage compensation signal. 15. The driving method of a backlight assembly according to claim 11, wherein the feedback compensation circuit comprises: a first error amplifier, receiving a first reference signal and the first feedback signal, and comparing the second reference signal with the first feedback signal to obtain an output; and A first voltage compensator is coupled between the output of the first error amplifier and the DC power converter, and generates and outputs the voltage compensation signal accordingly. 16. The driving method of the backlight assembly according to claim 11, further comprising: b1. The light-emitting diode drive circuit generates a second feedback signal, and the second feedback signal is from a coupling of a second light-adjusting circuit of the light-emitting elements corresponding to a second light-emitting element of the light-emitting elements obtained, and the second light emitting element is disposed in the lowest temperature region; and c1. The feedback compensation circuit receives the second feedback signal, and generates the voltage compensation signal according to the average value of the first feedback signal and the second feedback signal. 17. The driving method of a backlight assembly according to claim 16, wherein the feedback compensation circuit comprises: a second error amplifier, receiving a second reference signal, the first feedback signal and the second feedback signal, and comparing the average value of the second reference signal, the first feedback signal and the second feedback signal to obtain an output ;as well as A second voltage compensator is coupled between the output of the second error amplifier and the DC power converter, and generates and outputs the voltage compensation signal accordingly. 18. The driving method of a backlight assembly as claimed in claim 11, wherein a cooling device is disposed in the lowest temperature area, wherein the cooling device is a heat sink, a fan or a water cooling device. 19. The driving method of a backlight assembly as claimed in claim 11, wherein each of the light emitting elements comprises at least one light emitting diode. 20. The driving method of a backlight assembly according to claim 11, wherein, among the dimming circuits, each dimming circuit comprises: a switch, one end of which is coupled to a corresponding one of the light-emitting elements; and A certain current source is coupled between the switch and ground. 21. The driving method of a backlight assembly as claimed in claim 11, wherein the DC power converter adjusts the operating voltage in a pulse width modulation manner. 22. The driving method of a backlight assembly as claimed in claim 11, wherein the DC power converter is a boost DC power converter, a step-down DC power converter or a buck-boost DC power converter.

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