A backlight driving circuit, a backlight module and a display device

Abstract

The application discloses a backlight driving circuit, a backlight module and a display device. The backlight driving circuit comprises a driving module, a current sampling module, a voltage ripple sampling module, a feedback module and a controller. The driving module is used for providing a driving current for a backlight light bar. The current sampling module is used for outputting a sampling voltage signal according to the driving current. The voltage ripple sampling module is used for sampling a power supply voltage ripple of the backlight light bar to output a voltage ripple signal. The feedback module is used for providing a feedback voltage signal for the controller according to the sampling voltage signal and the voltage ripple signal. The controller is used for adjusting the driving current of the driving module according to the feedback voltage signal. The application can alleviate the flickering problem of the backlight lamp string caused by the power supply voltage fluctuation.

Description

Technical Field

[0001] This utility model relates to the field of electronic technology, and in particular to a backlight driving circuit, a backlight module, and a display device. Background Technology

[0002] Currently, LCD (Liquid Crystal Display) TVs and monitors commonly use LEDs as backlights. To achieve stable backlight brightness, it is necessary to stably control the LED current, i.e., constant current driving. LED constant current driving is divided into linear constant current and nonlinear constant current. Due to cost considerations, nonlinear constant current methods are increasingly used. However, the stability of nonlinear constant current driving is easily affected by fluctuations in the power supply voltage, causing the backlight brightness to flicker with voltage fluctuations.

[0003] Therefore, the existing technology still needs to be improved and enhanced. Utility Model Content

[0004] The purpose of this application is to provide a backlight driving circuit, a backlight module, and a display device that can effectively alleviate the backlight flickering problem caused by power supply voltage fluctuations.

[0005] To achieve the above objectives, this application adopts the following technical solution: This application provides a backlight driving circuit for use in a display device. The display device includes a backlight strip, and the backlight driving circuit includes: The driver module is connected to the backlight strip and is used to provide driving current to the backlight strip. The current sampling module is connected to the drive module; the current sampling module is used to output a sampled voltage signal based on the drive current. The voltage ripple sampling module is connected to the backlight strip and is used to sample the power supply voltage ripple of the backlight strip to output a voltage ripple signal. The feedback module is connected to the current sampling module and the voltage ripple sampling module respectively. The feedback module is used to provide a feedback voltage signal to the controller based on the sampled voltage signal and the voltage ripple signal. The controller is connected to both the drive module and the feedback module; the controller is used to adjust the drive current of the drive module according to the feedback voltage signal.

[0006] In some embodiments of the backlight driving circuit, the feedback module includes an adder, which is connected to the controller, the current sampling module and the voltage ripple sampling module respectively. The adder is used to add the sampled voltage signal and the voltage ripple signal to provide a feedback voltage signal to the controller.

[0007] In some embodiments of the backlight driving circuit, the adder includes a first resistor and a second resistor. One end of the first resistor is connected to a voltage ripple sampling module, and the other end of the first resistor is connected to a controller. One end of the second resistor is connected to a current sampling module, and the other end of the second resistor is connected to a controller.

[0008] In some embodiments of the backlight driving circuit, the voltage ripple sampling module includes a first capacitor, one end of which is connected to the input terminal of the backlight strip, and the other end of which is connected to the feedback module.

[0009] In some embodiments of the backlight driving circuit, the voltage ripple sampling module includes a first capacitor, one end of which is connected to the output terminal of the backlight strip, and the other end of which is connected to the feedback module.

[0010] In some embodiments of the backlight driving circuit, the driving module includes a switching transistor, an inductor, a third resistor, and a diode. The first end of the switching transistor is connected to the control terminal of the controller through the third resistor, the second end of the switching transistor is connected to the output terminal of the backlight strip through the inductor, the third end of the switching transistor is connected to the current sampling module, the anode of the diode is connected to the second end of the switching transistor, and the cathode of the diode is connected to the input terminal of the backlight strip.

[0011] In some embodiments of the backlight driving circuit, the current sampling module includes a fourth resistor, one end of which is connected to both the driving module and the feedback module, and the other end of which is grounded.

[0012] In some embodiments of the backlight driving circuit, the resistance value of the first resistor is greater than 1KΩ.

[0013] In some embodiments of the backlight driving circuit, the resistance value of the second resistor is greater than 100Ω.

[0014] In some embodiments of the backlight driving circuit, the backlight driving circuit further includes a first filtering module, which is connected to the input terminal of the backlight strip and is used to filter the power supply voltage of the backlight strip.

[0015] In some embodiments of the backlight driving circuit, the backlight driving circuit further includes a second filtering module, which is connected to the output terminal of the backlight strip and is used to filter the voltage input to the driving module.

[0016] In some embodiments of the backlight driving circuit, the first filtering module includes a second capacitor, one end of which is connected to the input terminal of the backlight strip, and the other end of which is grounded.

[0017] In some embodiments of the backlight driving circuit, the second filtering module includes a third capacitor, one end of which is connected to the output terminal of the backlight strip, and the other end of which is grounded.

[0018] This application embodiment also provides a backlight module, which includes a backlight strip and the aforementioned backlight driving circuit.

[0019] This application also provides a display device, which includes the backlight module described above.

[0020] This application provides a backlight driving circuit, a backlight module, and a display device. The backlight driving circuit samples the power supply voltage ripple by setting a voltage ripple sampling module and a feedback module to provide feedback voltage to the controller. This allows the fluctuation of the power supply voltage to be introduced into the current detection of the controller, thereby increasing the gain of the control loop, improving the loop response speed, and increasing the dynamic compensation of errors. This improves the reliability of current regulation and alleviates the flickering problem of the backlight string caused by power supply voltage fluctuations. Attached Figure Description

[0021] Figure 1 This is a first structural block diagram of the backlight driving circuit provided in an embodiment of this application.

[0022] Figure 2 This is a second structural block diagram of the backlight driving circuit provided in an embodiment of this application.

[0023] Figure 3 This is a third structural block diagram of the backlight driving circuit provided in the embodiments of this application.

[0024] Figure 4 This is a first circuit diagram of a backlight driving circuit provided in an embodiment of this application.

[0025] Figure 5 This is a second circuit diagram of the backlight driving circuit provided in an embodiment of this application.

[0026] Figure 6 The diagram shows the waveform of the power supply voltage fluctuation in the backlight driving circuit provided in the embodiments of this application, the voltage waveform of the fourth resistor, and the voltage waveform of the first resistor. Detailed Implementation

[0027] The purpose of this application is to provide a backlight driving circuit, an antenna device, and an electronic device. The backlight driving circuit can alleviate the problem that current antenna designs cannot achieve the expected receiving gain, and is beneficial to improving the overall performance of the antenna system.

[0028] To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following detailed description of this application is provided with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining this application and are not intended to limit this application.

[0029] Please see Figure 1 This application provides a backlight driving circuit, which is applied in a display device. The display device includes a backlight strip 10, and the backlight driving circuit is used to drive the backlight strip 10 to light up. Specifically, the backlight driving circuit includes a driving module 100, a current sampling module 200, a voltage ripple sampling module 300, a feedback module 400, and a controller 500. The driving module 100 is connected to the backlight strip 10, the current sampling module 200 is connected to the driving module 100, the voltage ripple sampling module 300 is connected to the backlight strip 10, and the feedback module 400 is connected to the voltage ripple sampling module 300, the current sampling module 200, and the controller 500. The controller 500 is also connected to the driving module 100.

[0030] The drive module 100 provides drive current to the backlight strip 10; the current sampling module 200 outputs a sampled voltage signal based on the drive current; the voltage ripple sampling module 300 samples the power supply voltage ripple of the backlight strip 10 to output a voltage ripple signal; the feedback module 400 provides a feedback voltage signal to the controller 500 based on the sampled voltage signal and the voltage ripple signal; and the controller 500 adjusts the drive current of the drive module 100 based on the feedback voltage signal.

[0031] The controller 500 acquires a sampled voltage signal through the current sampling module 200, compares the sampled voltage signal with a reference voltage, and outputs an error signal. Then, it controls the drive module 100 to adjust the drive current based on the error signal. Because the current detection circuit inside the controller 500 has a filtering section, there is a delay in responding to current changes caused by voltage fluctuations. Furthermore, the controller 500 detects a pulse signal, which needs to be converted to a DC signal, resulting in errors and insufficient correction of the drive current. In this application, a voltage ripple sampling module 300 samples the supply voltage ripple to output a voltage ripple signal. This signal is then fed back to the controller 500 via a feedback module 400. This introduces supply voltage fluctuations into the current detection of the controller 500, thereby increasing the gain of the control loop, improving the loop's response speed, and increasing the dynamic compensation for errors. This improves the reliability of current regulation and helps to further alleviate the flickering problem of the backlight string caused by supply voltage fluctuations.

[0032] In some embodiments, the feedback module 400 includes an adder connected to the controller 500, the current sampling module 200, and the voltage ripple sampling module 300, respectively. The adder is used to add the sampled voltage signal and the voltage ripple signal to provide the feedback voltage signal to the controller 500. In this embodiment, by setting the adder as the feedback module 400, the adder adds the voltage sampling signal and the voltage ripple signal and outputs the result to the controller 500, thereby introducing the fluctuation of the supply voltage into the controller 500 to increase the gain of the control loop.

[0033] Please see Figure 2 In some embodiments, the backlight driving circuit further includes a first filtering module 600, which is connected to the input terminal of the backlight strip 10. The first filtering module 600 filters the power supply voltage of the backlight strip 10 before supplying power to the backlight strip 10, which helps to improve the stability of the power supply voltage. In this embodiment, the voltage ripple sampling module 300 can be connected to either the input terminal or the output terminal of the backlight strip 10. When the voltage ripple sampling module 300 is connected to the input terminal of the backlight strip 10, it can sample the power supply voltage after it has been filtered by the first filtering module 600 to obtain the fluctuation of the power supply voltage.

[0034] Please see Figure 3 In some embodiments, the backlight driving circuit further includes a second filtering module 700, which is connected to the output terminal of the backlight strip 10. The second filtering module 700 is used to filter the voltage input to the driving module 100, improving the voltage stability of the input to the driving module 100 and ensuring the reliability of the driving module 100. In this embodiment, when the voltage ripple sampling module 300 is connected to the output terminal of the backlight strip 10, the voltage ripple sampling module 300 can be connected to the second filtering module 700. The voltage ripple sampling module 300 samples the voltage after it has been filtered by the second filtering module 700, thereby obtaining the power supply voltage of the backlight strip 10.

[0035] Please see Figure 4In one embodiment, the adder includes a first resistor R1 and a second resistor R2. One end of the first resistor R1 is connected to the voltage ripple sampling module 300, and the other end is connected to the controller 500. One end of the second resistor R2 is connected to the current sampling module 200, and the other end is connected to the controller 500. In this embodiment, by setting resistors as adders to perform voltage division processing on the voltage ripple signal, the fluctuation of the supply voltage is input to the controller 500 along with the current detection, so as to increase the gain of the control loop. At the same time, the circuit structure does not contain other complex electronic components, which simplifies the circuit structure.

[0036] In one embodiment, the voltage ripple sampling module 300 includes a first capacitor C1. One end of the first capacitor C1 is connected to the input terminal (e.g., Vled+ terminal) of the backlight strip 10, and the other end of the first capacitor C1 is connected to one end of a first resistor R1. The other end of the first resistor R1 is connected to the detection terminal (e.g., terminal A) of the controller 500. In this embodiment, by connecting the first capacitor C1 and the first resistor R1 to the input terminal of the backlight strip 10, the first capacitor C1 blocks DC and passes AC, and the first resistor R1 divides the voltage to detect the supply voltage, so as to obtain the fluctuation of the supply voltage and add it to the detection terminal of the controller 500.

[0037] Please see Figure 5 In another embodiment, the voltage ripple sampling module 300 includes a first capacitor C1. One end of the first capacitor C1 is connected to the output terminal (e.g., Vled- terminal) of the backlight strip 10, and the other end of the first capacitor C1 is connected to one end of a first resistor R1. The other end of the first resistor R1 is connected to the detection terminal of the controller 500. That is, in this embodiment, the first capacitor C1 and the first resistor R1 are set at the output terminal of the backlight strip 10. After the first capacitor C1 blocks DC and passes AC, the supply voltage is detected by voltage division through the first resistor R1. Similarly, the fluctuation of the supply voltage can be obtained and added to the detection terminal of the controller 500.

[0038] In one embodiment, the driving module 100 includes a switch Q1, an inductor L1, a third resistor R3, and a diode D1. The first terminal of the switch Q1 is connected to the control terminal (e.g., terminal B) of the controller 500 through the third resistor R3. The second terminal of the switch Q1 is connected to the output terminal of the backlight strip 10 through the inductor L1. The third terminal of the switch Q1 is connected to the current sampling module 200. The anode of the diode D1 is connected to the second terminal of the switch Q1, and the cathode of the diode D1 is connected to the input terminal of the backlight strip 10. In this embodiment, the inductor L1 is an energy storage inductor L1, which stores electrical energy when the switch Q1 is turned on and releases electrical energy through the diode D1 when the switch Q1 is turned off. The diode D1 also serves as a freewheeling diode, providing a freewheeling path for the inductor L1 when the switch Q1 is turned off. In this embodiment, the control terminal of the controller 500 is connected to the first terminal of the switch Q1. If the switch Q1 is a MOSFET, the first terminal of the switch Q1 is the gate of the MOSFET. The controller 500 can regulate the drive current by controlling the duty cycle of the switching transistor Q1.

[0039] In one embodiment, the current sampling module 200 includes a fourth resistor R4. One end of the third resistor R3 is connected to the detection terminal of the controller 500, one end of the fourth resistor R4 is connected to the drive module 100 and the other end of the third resistor R3, and the other end of the fourth resistor R4 is grounded. In this embodiment, the fourth resistor R4 is a sampling resistor, which can sample the drive current flowing through the backlight strip 10 and convert it into a sampling voltage signal to be output to the feedback module 400. The controller 500 can control the duty cycle of the switching transistor Q1 according to the feedback voltage signal output by the feedback module 400, so as to adjust the drive circuit and alleviate the backlight flicker problem.

[0040] As one embodiment, the resistance of the first resistor R1 is greater than 1KΩ, and the resistance of the second resistor R2 is greater than 100Ω. For example, the resistance of the first resistor R1 is 680KΩ, the resistance of the second resistor R2 is 510Ω, and the resistance of the fourth resistor R4 is 0.47Ω. The voltage corresponding to the voltage ripple signal is denoted as V1, the voltage of the voltage sampling signal is denoted as V2, and the voltage corresponding to the feedback voltage signal is denoted as V3. V1 and V2 are processed by an adder, V3 = V1 × (R2 + R4) / (R1 + R2 + R4) + V1 × R1 / ((R1 + R2)), where V3 corresponds to the voltage at the detection terminal of the controller 500, i.e., VA. When the power supply voltage of the backlight strip 10 fluctuates, such as Vled+ fluctuating, the waveform of Vled+ is as follows... Figure 6 As shown, the voltage corresponding to the fourth resistor R4 is V. R4 Waveform as Figure 6 As shown, if a first resistor R1 and a first capacitor C1 are provided, the voltage waveform at the detection terminal of the controller 500 side is as follows. Figure 6As shown, the detection terminal on the controller 500 side can detect fluctuations in the power supply voltage, which is equivalent to providing a correction compensation for the adjustment of the drive current, ensuring the accuracy and reliability of the adjustment, thereby alleviating the flickering problem caused by power supply voltage fluctuations.

[0041] In one embodiment, the first filtering module 600 includes a second capacitor C2, one end of which is connected to the input terminal of the backlight strip 10, and the other end of which is grounded. In this embodiment, by connecting a capacitor in parallel to the input terminal of the backlight strip 10, the power supply voltage of the backlight strip 10 can be filtered to improve the reliability of the power supply voltage.

[0042] In one embodiment, the second filtering module 700 includes a third capacitor C3, one end of which is connected to the output terminal of the backlight strip 10, and the other end of which is grounded. Similarly, in this embodiment, a capacitor is connected in parallel at the output terminal of the backlight strip 10 to filter the output voltage of the backlight strip 10, which helps to improve the stability of the driving module 100.

[0043] The backlight driving circuit in this application can increase the gain of the current control loop by setting conventional components such as resistors and capacitors, thereby increasing the dynamic error compensation of the loop and improving the loop response speed. This can further alleviate the backlight flicker problem. At the same time, the circuit structure is simple, which is conducive to the miniaturization design of the backlight driving circuit. Its application in display devices can help reduce product costs.

[0044] This application embodiment also provides a backlight module, which includes a backlight strip and the aforementioned backlight driving circuit. This backlight driving circuit helps to further alleviate backlight flickering and optimizes the display effect of the backlight module. Since the backlight driving circuit has been described in detail above, it will not be repeated here.

[0045] This application also provides a display device, which includes the backlight module described above. Since the backlight module has been described in detail above, it will not be repeated here.

[0046] The backlight driving circuit provided in the embodiments of this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A backlight driving circuit, applied in a display device, the display device including a backlight strip, characterized in that, The backlight driving circuit includes: A driving module is connected to the backlight strip and is used to provide driving current to the backlight strip. A current sampling module is connected to the drive module; the current sampling module is used to output a sampled voltage signal based on the drive current. A voltage ripple sampling module is connected to the backlight strip and is used to sample the power supply voltage ripple of the backlight strip to output a voltage ripple signal. A feedback module is connected to both the current sampling module and the voltage ripple sampling module. The feedback module is used to output a feedback voltage signal based on the sampled voltage signal and the voltage ripple signal. A controller is connected to both the drive module and the feedback module; the controller is used to adjust the drive current of the drive module according to the feedback voltage signal.

2. The backlight driving circuit according to claim 1, wherein The feedback module includes an adder, which is connected to the controller, the current sampling module, and the voltage ripple sampling module. The adder is used to add the sampled voltage signal and the voltage ripple signal to provide the feedback voltage signal to the controller.

3. The backlight driving circuit according to claim 2, characterized in that, The adder includes a first resistor and a second resistor. One end of the first resistor is connected to the voltage ripple sampling module, and the other end of the first resistor is connected to the controller. One end of the second resistor is connected to the current sampling module, and the other end of the second resistor is connected to the controller.

4. The backlight driving circuit according to claim 1, wherein The voltage ripple sampling module includes a first capacitor, one end of which is connected to the input terminal of the backlight strip, and the other end of which is connected to the feedback module.

5. The backlight driving circuit according to claim 1, wherein The voltage ripple sampling module includes a first capacitor, one end of which is connected to the output terminal of the backlight strip, and the other end of which is connected to the feedback module.

6. The backlight driving circuit according to claim 1, characterized in that, The driving module includes a switching transistor, an inductor, a third resistor, and a diode. The first end of the switching transistor is connected to the control terminal of the controller through the third resistor. The second end of the switching transistor is connected to the output terminal of the backlight strip through the inductor. The third end of the switching transistor is connected to the current sampling module. The anode of the diode is connected to the second end of the switching transistor, and the cathode of the diode is connected to the input terminal of the backlight strip.

7. The backlight driving circuit according to claim 6, characterized in that, The current sampling module includes a fourth resistor, one end of which is connected to the driving module and the feedback module, and the other end of which is grounded.

8. The backlight driving circuit according to claim 3, characterized in that, The resistance of the first resistor is greater than 1KΩ.

9. The backlight driving circuit according to claim 3, characterized in that, The resistance of the second resistor is greater than 100Ω.

10. The backlight driving circuit according to any one of claims 1-9, wherein, The backlight driving circuit further includes a first filtering module, which is connected to the input terminal of the backlight strip. The first filtering module is used to filter the power supply voltage of the backlight strip.

11. The backlight driving circuit according to any one of claims 1-9, wherein, The backlight driving circuit further includes a second filtering module, which is connected to the output terminal of the backlight strip. The second filtering module is used to filter the voltage input to the driving module.

12. The backlight driving circuit according to claim 10, characterized in that, The first filtering module includes a second capacitor, one end of which is connected to the input terminal of the backlight strip, and the other end of which is grounded.

13. The backlight driving circuit of claim 11, wherein, The second filtering module includes a third capacitor, one end of which is connected to the output terminal of the backlight strip, and the other end of which is grounded.

14. A backlight module, characterized in that, The backlight module includes a backlight strip and a backlight driving circuit as described in any one of claims 1-13.

15. A display device, characterized by The display device includes the backlight module as described in claim 14.

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