Bias voltage power supply circuit of LCD (Liquid Crystal Display) screen

Abstract

The utility model discloses a bias voltage power supply circuit of a liquid crystal display (LCD) screen, which is characterized in that a first end of an energy storage unit is electrically connected with an input end of a direct current-direct current (DC-DC) power supply chip, and a second end of the energy storage unit is jointly connected with an output end of the DC-DC power supply chip, a first end of a first coupling unit and a first end of a second coupling unit; the second end of the first coupling unit is electrically connected with the first end of the first rectifying unit, the second end of the second coupling unit is electrically connected with the first end of the second rectifying unit, and the second end of the first rectifying unit and the second end of the second rectifying unit are electrically connected with the first output unit and the second output unit respectively; and the first output unit and the second output unit are used for respectively outputting positive voltage and negative voltage to the LCD screen. The DC-DC power supply chip, the coupling capacitor and the rectifier bridge are utilized to form the bias voltage circuit of the LCD screen, a traditional bias power supply chip circuit is replaced to obtain the positive voltage and the negative voltage, the positive voltage and the negative voltage are output to the LCD screen, and therefore a blind hole technology does not need to be adopted, the technology complexity is reduced, and meanwhile the cost of the circuit is reduced.

Description

Technical Field

[0001] This utility model relates to the field of bias voltage technology for LCD screens, and in particular to a bias voltage power supply circuit for an LCD screen. Background Technology

[0002] LCD bias voltage refers to the voltage used in a liquid crystal display (LCD) to control the deflection of liquid crystal molecules. A proper bias voltage allows the liquid crystal molecules to deflect at corresponding angles under different voltage conditions, thereby precisely controlling the light transmittance of each pixel and achieving accurate image display. By adjusting the bias voltage, the contrast of the LCD can be changed, resulting in clearer and more vivid images to meet the display needs of different users. It is typically generated by a dedicated power management chip or circuit, such as the MAX1578 chip, which contains three advanced charge pumps for LCD bias power, providing fixed +5V, +15V, and -10V voltages without the need for external diodes, meeting the voltage requirements of small active matrix TFT-LCD displays. Alternatively, other methods can be used... Figure 1 The bias power supply circuit composed of U1702: 5V (VBAT_SYS) voltage is input to U1702 (bias voltage IC), and the U1702 chip directly converts and outputs positive and negative VSP / VSN voltages.

[0003] However, due to the small PCB package size of the bias voltage chip, the PCB design requires blind via technology, which is costly. In addition, the cost of the bias voltage chip is generally relatively high. Utility Model Content

[0004] In the existing technology, the bias voltage of the LCD screen is obtained by using a power supply circuit composed of a bias voltage chip. Due to the small package size, the process is not only complex, but also the cost is high.

[0005] To address the aforementioned issues, a bias voltage power supply circuit for an LCD screen is proposed. This circuit utilizes a DC-DC power supply chip, coupling capacitors, and a rectifier bridge to form the bias voltage circuit for the LCD screen, replacing the traditional bias power supply chip circuit. This provides positive and negative voltages that are output to the LCD screen, eliminating the need for blind via technology, reducing process complexity, and lowering circuit costs.

[0006] In a first aspect, a bias voltage power supply circuit for an LCD screen includes:

[0007] DC-DC power supply chip;

[0008] Energy storage unit;

[0009] First coupling unit and second coupling unit;

[0010] First rectifier unit and second rectifier unit;

[0011] First output unit and second output unit;

[0012] The first end of the energy storage unit is electrically connected to the input end of the DC-DC power chip, and the second end is connected to the output end of the DC-DC power chip, the first end of the first coupling unit, and the first end of the second coupling unit. The second end of the first coupling unit is electrically connected to the first end of the first rectifier unit, and the second end of the second coupling unit is electrically connected to the first end of the second rectifier unit. The second ends of the first rectifier unit and the second rectifier unit are respectively electrically connected to the first output unit and the second output unit.

[0013] The first output unit and the second output unit are used to output positive voltage and negative voltage to the LCD screen, respectively.

[0014] In conjunction with the bias voltage power supply circuit for the LCD screen described in the first aspect of this utility model, in a first possible embodiment, the DC-DC power supply chip includes:

[0015] Input pins and output pins;

[0016] The input power supply and the first end of the energy storage unit are electrically connected to the input pin, and the second end of the energy storage unit is electrically connected to the output pin;

[0017] The output pin is used to output a PWM waveform at a specified frequency.

[0018] In conjunction with the first possible implementation of the first aspect of this utility model, in the second possible implementation, the bias voltage power supply circuit of the LCD screen further includes a feedback unit.

[0019] The DC-DC power supply chip also includes a feedback pin;

[0020] The first output unit is electrically connected to the feedback pin through the feedback unit.

[0021] In conjunction with the second possible implementation of the first aspect of this utility model, in the third possible implementation, the first rectifier unit includes:

[0022] First rectifier diode and second rectifier diode;

[0023] After the anode of the first rectifier diode and the cathode of the second rectifier diode are connected together, they are electrically connected to the second terminal of the first coupling unit;

[0024] The cathode of the first rectifier diode is electrically connected to the second output unit, and the anode of the second rectifier diode is grounded;

[0025] The first output unit is used to output a positive voltage.

[0026] In conjunction with the second possible implementation of the first aspect of this utility model, in the fourth possible implementation, the second rectifier unit includes:

[0027] The third rectifier diode and the fourth rectifier diode;

[0028] The cathode of the third rectifier diode and the anode of the fourth rectifier diode are connected together and then electrically connected to the second terminal of the second coupling unit.

[0029] The anode of the third rectifier diode is electrically connected to the second output unit, and the cathode of the fourth rectifier diode is grounded.

[0030] The second output unit is used to output a negative voltage.

[0031] In conjunction with the first possible implementation of the first aspect of this utility model, in the fifth possible implementation, the bias voltage power supply circuit of the LCD screen further includes an enable control unit.

[0032] The DC-DC power supply chip also includes an enable control pin;

[0033] The first terminal of the enabling control unit is electrically connected to the control unit, and the second terminal is electrically connected to the enabling control pin.

[0034] In conjunction with the first possible embodiment of the first aspect of this utility model, in the sixth possible embodiment, the first output unit includes:

[0035] First filtering module;

[0036] The first filtering module is used to filter the output positive voltage.

[0037] In conjunction with the first possible embodiment of the first aspect of this utility model, in the seventh possible embodiment, the second output unit includes:

[0038] Second filtering module;

[0039] The second filtering module is used to filter the output negative voltage.

[0040] In conjunction with the first possible implementation of the first aspect of this utility model, in the eighth possible implementation, the energy storage unit adopts an energy storage inductor;

[0041] The first end of the energy storage inductor is electrically connected to the input end of the DC-DC power chip, and the second end is connected to the output end of the DC-DC power chip, the first end of the first coupling unit, and the first end of the second coupling unit.

[0042] In conjunction with the first possible implementation of the first aspect of this utility model, in the ninth possible implementation, the first coupling unit and the second coupling unit respectively adopt a first coupling capacitor and a second coupling capacitor;

[0043] The second end of the energy storage inductor is connected to the output end of the DC-DC power chip, the first end of the first coupling capacitor, and the first end of the second coupling capacitor; the second end of the first coupling capacitor is electrically connected to the first end of the first rectifier unit, and the second end of the second coupling capacitor is electrically connected to the first end of the second rectifier unit. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A circuit diagram for the bias voltage power supply of an LCD screen in the prior art;

[0046] Figure 2 This is a schematic diagram of the bias voltage power supply circuit module connection for the LCD screen in this utility model.

[0047] Figure 3 The circuit diagram for the bias voltage power supply of the LCD screen in this utility model;

[0048] Figure 4 A flowchart illustrating the steps of a specific embodiment of the bias voltage power supply method for an LCD screen according to this utility model;

[0049] Figure 5 A flowchart illustrating the steps of another specific embodiment of the bias voltage power supply method for the LCD screen in this utility model;

[0050] Components and their serial numbers:

[0051] 100 – DC-DC power supply chip, 200 – energy storage unit, 300 – first coupling unit, 400 – second coupling unit, 500 – first rectifier unit, 600 – second rectifier unit, 700 – first output unit, 800 – second output unit, 900 – LCD screen. Detailed Implementation

[0052] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, other embodiments obtained by those skilled in the art without creative effort are all within the scope of protection of this utility model.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0054] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0055] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0057] In existing technologies, the bias voltage of the LCD screen 900 is obtained using a power supply circuit composed of a bias voltage chip. Due to its small package size, this method is not only complex in manufacturing process but also expensive. Figure 1 , Figure 1 The circuit diagram for bias voltage supply in the prior art; LCD screen 900 bias voltage control, such as... Figure 1A 5V (VBAT_SYS) voltage is input to the U1702 (bias voltage IC), which directly converts and outputs the positive and negative voltages (VSN) of VSP / VSN. Due to the small package size, the PCB design requires blind via technology, which increases costs, and the chip itself is relatively expensive.

[0058] To address the above issues, a bias voltage power supply circuit for an LCD screen 900 is proposed.

[0059] Firstly, a bias voltage power supply circuit for an LCD screen 900, such as... Figure 2 , Figure 2 This is a schematic diagram of the bias voltage power supply circuit module connection for the LCD screen 900 in this utility model; it includes a DC-DC power chip 100, an energy storage unit 200, a first coupling unit 300 and a second coupling unit 400, a first rectifier unit 500 and a second rectifier unit 600, a first output unit 700 and a second output unit 800; the first terminal of the energy storage unit 200 is electrically connected to the input terminal of the DC-DC power chip 100, and the second terminal is connected to the output terminal of the DC-DC power chip 100 and the first terminal of the first coupling unit 300. The first terminal of the second coupling unit 400 is connected to the first terminal of the first coupling unit 300, and the second terminal of the second coupling unit 400 is electrically connected to the first terminal of the second rectifier unit 600. The second terminals of the first rectifier unit 500 and the second rectifier unit 600 are electrically connected to the first output unit 700 and the second output unit 800, respectively. The first output unit 700 and the second output unit 800 are used to output positive voltage (VSP) and negative voltage (VSN) to the LCD screen 900, respectively. By using the DC-DC power supply chip 100, coupling capacitor, and rectifier bridge to form the bias voltage circuit of the LCD screen 900, replacing the traditional bias power supply chip 100 circuit, positive voltage (VSP) and negative voltage (VSN) are obtained and output to the LCD screen 900. This eliminates the need for blind via technology, reduces process complexity, and lowers circuit cost.

[0060] In this embodiment, the DC-DC power chip 100 performs pulse width modulation on the input 5V power supply voltage and outputs a PWM waveform. The energy storage unit 200 is used to maintain a stable output voltage. The output PWM waveform is superimposed on the voltage waveform of the energy storage unit 200, and then outputs a sine wave through the first coupling unit 300 and the second coupling unit 400 respectively. After rectification by the first rectification unit 500 and the second rectification unit 600, a positive voltage (VSP) and a negative voltage (VSN) are obtained and output to the LCD screen 900.

[0061] In this embodiment, the first coupling unit 300 and the second coupling unit 400 respectively use coupling capacitors (C5 and C6) to convert the output PWM waveform into a sine waveform.

[0062] Preferably, such as Figure 3 , Figure 3 This is a circuit diagram of the bias voltage power supply for the LCD screen 900 in this utility model; the DC-DC power chip 100 includes an input pin VIN and an output pin SW; the first end of the input power supply and energy storage unit 200 is electrically connected to the input pin VIN, and the second end of the energy storage unit 200 is electrically connected to the output pin SW; the output pin SW is used to output a PWM waveform of a specified frequency.

[0063] In this embodiment, the frequency of the PWM waveform is preferably 1.2MHz. The energy storage unit 200 is equivalent to being connected in parallel across the DC-DC power chip 100. It stores energy when the switch is on and outputs electrical energy when the switch is off, thus maintaining the stability of the output voltage.

[0064] In this embodiment, the energy storage unit 200 uses an energy storage inductor L1, which is connected in parallel across the two ends of the DC-DC power chip 100 and is shared with the first coupling unit 300 and the second coupling unit 400.

[0065] Preferably, the bias voltage power supply circuit of the LCD screen 900 further includes a feedback unit; the DC-DC power chip 100 further includes a feedback pin FB; the first output unit 700 is electrically connected to the feedback pin FB through the feedback unit. The feedback unit is used to provide feedback on the voltage signal output by the first output unit 700 and to adjust it to maintain output stability.

[0066] like Figure 3 The feedback unit includes resistors (R2, R3) and capacitor C4, and its circuit structure is as follows: Figure 3 As shown.

[0067] Preferably, the first rectifier unit 500 includes a first rectifier diode D1 and a second rectifier diode D2; the anode of the first rectifier diode D1 and the cathode of the second rectifier diode D2 are connected together and electrically connected to the second terminal of the first coupling unit 300; the cathode of the first rectifier diode D1 is electrically connected to the second output unit 800, and the anode of the second rectifier diode D2 is grounded; the first output unit 700 is used to output a positive voltage (VSP).

[0068] Preferably, the second rectifier unit 600 includes a third rectifier diode D3 and a fourth rectifier diode D4; the cathode of the third rectifier diode D3 and the anode of the fourth rectifier diode D4 are connected together and electrically connected to the second terminal of the second coupling unit 400; the anode of the third rectifier diode D3 is electrically connected to the second output unit 800, and the cathode of the fourth rectifier diode D4 is grounded; the second output unit 800 is used to output a negative voltage (VSN).

[0069] In this embodiment, the enable control unit includes a resistor R1 and a capacitor C3, which are electrically connected to the control unit or MCU and are used to control the DC-DC power chip 100 to turn on.

[0070] Preferably, the first output unit 700 includes a first filtering module; the first filtering module is used to filter the output positive voltage (VSP).

[0071] In this embodiment, the first output unit 700 further includes a conversion resistor R5, and the first filter module includes capacitors C9 and C10, and its circuit structure is as follows. Figure 3 As shown.

[0072] Preferably, the second output unit 800 includes a second filtering module; the second filtering module is used to filter the output negative voltage (VSN).

[0073] In this embodiment, the second output unit 800 further includes a conversion resistor R4, and the second filter module includes capacitors C7 and C8, and its circuit structure is as follows. Figure 3 As shown.

[0074] Preferably, the bias voltage power supply circuit of the LCD screen 900 further includes an enable control unit; the DC-DC power chip 100 further includes an enable control pin EN; the first end of the enable control unit is electrically connected to the control unit, and the second end is electrically connected to the enable control pin EN.

[0075] like Figure 3 The circuit, which is composed of DC-DC power chip 100 and rectifier diodes, converts DC power to positive and negative power. It mainly uses the pulse width modulation (PWM) output from pin 1 of the DC-DC chip to convert it into sinusoidal AC power through the coupling capacitors C5 and C6. Then, it outputs negative voltage (VSN) and positive voltage (VSP) through the bridge rectifier diodes D1, D2, D3, and D4.

[0076] The normal operating procedure is as follows: when EN outputs a high level, 5V power is input to pin 5 of DC-DC power chip 100, and DC-DC power chip 100 starts working. Pin 1 (SW) of DC-DC power chip 100 outputs a 1.2MHz pulse width modulation (PWM) signal, which is converted into sinusoidal AC power by coupling capacitors C411 and C412. Then, it passes through the bridge rectifier circuit D1 and D2 rectifier diodes (IN4148) to output a positive voltage (VSP). Through rectifier diodes D3 and D4, it outputs a negative voltage (VSN). The output positive voltage (VSP) and the voltage divider circuit composed of R4 and R5 are fed back by pin 3 (FB) of DC-DC power chip 100 to adjust and stabilize the output voltage.

[0077] Secondly, a bias voltage power supply method for an LCD screen 900, such as... Figure 4 , Figure 4 This is a flowchart illustrating the steps of a specific embodiment of the bias voltage power supply method for the LCD screen 900 of this utility model. The bias voltage power supply circuit for the LCD screen 900 using the first aspect includes: S100, inputting the power supply voltage to be converted into the DC-DC power chip 100 and storing energy using the energy storage unit 200, the DC-DC power chip 100 performing pulse width modulation on the power supply voltage and outputting a PWM waveform; S200, superimposing the voltage waveform output by the energy storage unit 200 with the PWM waveform, and performing a first coupling and a second coupling on the superimposed AC voltage waveform to obtain a first sine wave and a second sine wave, respectively; S300, performing a first rectification and a second rectification on the first sine wave and the second sine wave, respectively, to obtain a positive voltage (VSP) and a negative voltage (VSN), respectively.

[0078] Preferably, such as Figure 5 , Figure 5 This is a flowchart illustrating the steps of another specific embodiment of the bias voltage power supply method for the LCD screen 900 in this utility model; the method further includes: S400, performing a first filter and a second filter on the positive voltage (VSP) and negative voltage (VSN) respectively; S500, converting the positive current and negative current obtained after filtering to obtain positive voltage (VSP) and negative voltage (VSN) which are output to the LCD screen 900 respectively.

[0079] The present invention provides a bias voltage power supply circuit for an LCD screen 900. By using a DC-DC power supply chip 100, coupling capacitors, and a rectifier bridge to form the bias voltage circuit of the LCD screen 900, the traditional bias power supply chip 100 circuit is replaced to obtain positive voltage (VSP) and negative voltage (VSN) and output them to the LCD screen 900. This eliminates the need for blind via technology, reduces process complexity, and lowers circuit cost.

[0080] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A bias voltage power supply circuit for an LCD screen, characterized in that, include: DC-DC power supply chip; Energy storage unit; First coupling unit and second coupling unit; First rectifier unit and second rectifier unit; First output unit and second output unit; The first end of the energy storage unit is electrically connected to the input end of the DC-DC power chip, and the second end is connected to the output end of the DC-DC power chip, the first end of the first coupling unit, and the first end of the second coupling unit. The second end of the first coupling unit is electrically connected to the first end of the first rectifier unit, and the second end of the second coupling unit is electrically connected to the first end of the second rectifier unit. The second ends of the first rectifier unit and the second rectifier unit are respectively electrically connected to the first output unit and the second output unit. The first output unit and the second output unit are used to output positive voltage and negative voltage to the LCD screen, respectively.

2. The bias voltage power supply circuit for the LCD screen according to claim 1, characterized in that, The DC-DC power supply chip includes: Input pins and output pins; The input power supply and the first end of the energy storage unit are electrically connected to the input pin, and the second end of the energy storage unit is electrically connected to the output pin; The output pin is used to output a PWM waveform at a specified frequency.

3. The bias voltage power supply circuit for the LCD screen according to claim 2, characterized in that, The bias voltage power supply circuit of the LCD screen also includes a feedback unit; The DC-DC power supply chip also includes a feedback pin; The first output unit is electrically connected to the feedback pin through the feedback unit.

4. The bias voltage power supply circuit for the LCD screen according to claim 3, characterized in that, The first rectifier unit includes: First rectifier diode and second rectifier diode; After the anode of the first rectifier diode and the cathode of the second rectifier diode are connected together, they are electrically connected to the second terminal of the first coupling unit; The cathode of the first rectifier diode is electrically connected to the second output unit, and the anode of the second rectifier diode is grounded; The first output unit is used to output a positive voltage.

5. The bias voltage power supply circuit for the LCD screen according to claim 3, characterized in that, The second rectifier unit includes: The third rectifier diode and the fourth rectifier diode; The cathode of the third rectifier diode and the anode of the fourth rectifier diode are connected together and then electrically connected to the second terminal of the second coupling unit. The anode of the third rectifier diode is electrically connected to the second output unit, and the cathode of the fourth rectifier diode is grounded. The second output unit is used to output a negative voltage.

6. The bias voltage power supply circuit for the LCD screen according to claim 2, characterized in that, The bias voltage power supply circuit of the LCD screen also includes an enable control unit; The DC-DC power supply chip also includes an enable control pin; The first terminal of the enabling control unit is electrically connected to the control unit, and the second terminal is electrically connected to the enabling control pin.

7. The bias voltage power supply circuit for the LCD screen according to claim 2, characterized in that, The first output unit includes: First filtering module; The first filtering module is used to filter the output positive voltage.

8. The bias voltage power supply circuit for the LCD screen according to claim 2, characterized in that, The second output unit includes: Second filtering module; The second filtering module is used to filter the output negative voltage.

9. The bias voltage power supply circuit for the LCD screen according to any one of claims 1-8, characterized in that, The energy storage unit uses an energy storage inductor; The first end of the energy storage inductor is electrically connected to the input end of the DC-DC power chip, and the second end is connected to the output end of the DC-DC power chip, the first end of the first coupling unit, and the first end of the second coupling unit.

10. The bias voltage power supply circuit for the LCD screen according to claim 9, characterized in that, The first coupling unit and the second coupling unit respectively adopt a first coupling capacitor and a second coupling capacitor; The second end of the energy storage inductor is connected to the output end of the DC-DC power chip, the first end of the first coupling capacitor, and the first end of the second coupling capacitor; the second end of the first coupling capacitor is electrically connected to the first end of the first rectifier unit, and the second end of the second coupling capacitor is electrically connected to the first end of the second rectifier unit.

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