Driving circuit and liquid crystal display device

Abstract

The utility model discloses a driving circuit and a liquid crystal display device, and the driving circuit comprises a power supply which outputs a power supply voltage and a plurality of DC voltages from a first voltage to a sixth voltage; the time sequence controller is connected with a power supply, receives power supply voltage and outputs a control signal; the selection circuit is connected with a power supply, receives the third voltage, the fourth voltage, the fifth voltage, the sixth voltage and the visual angle switching signal, and outputs a first selection signal and a second selection signal which are opposite in voltage polarity but identical in absolute value; the square wave output circuit is connected with the power supply, the time schedule controller and the selection circuit, receives the first voltage, the second voltage, the control signal, the first selection signal and the second selection signal, and provides an output voltage as a driving voltage for the display panel, and the control signal and the output voltage are both square wave signals; and the output voltage is a positive and negative voltage square wave signal formed by alternately combining the first selection signal and the second selection signal. The driving circuit is simple in structure, small in size and low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid crystal display, in particular to a driving circuit and a liquid crystal display device. Background Art

[0002] Liquid crystal display devices have been widely used in mobile terminals and display panels due to their advantages of good display quality, small size and low power consumption. With the continuous advancement of liquid crystal display technology, the viewing angle of the display has been widened from the original 112° to more than 122°. However, while people enjoy the visual experience brought by the wide viewing angle, they also hope to effectively protect business secrets and personal privacy to avoid business losses or embarrassment caused by the leakage of screen information. Therefore, in addition to the demand for wide viewing angle, in many occasions, the display device is also required to have the function of switching between wide and narrow viewing angles.

[0003] Figure 1 A schematic structural block diagram of a driving circuit of an existing display device is shown. Figure 1 As shown, the display device includes a display panel 200 with switchable viewing angle and a driving circuit for controlling the viewing angle switching of the display panel, and the driving circuit can be located on a printed circuit board PCBA100. The display panel 200 includes a display box 201 and a dimming box 202, the display box 201 is used to display the picture, and the dimming box 202 is used to switch the viewing angle. The driving circuit provides a driving voltage to the dimming box 202 to control the dimming box 202 to adjust the viewing angle display mode of the display panel 200. The driving circuit includes an MCU (Microcontroller Unit) 102, a DAC (Digital to analog converter) 103 and an operational amplifier 104 connected in sequence. The host burns the written code code into the MCU102, and the MCU102 automatically runs the code after powering on, and outputs a string of digital signals Vd when receiving the viewing angle switching signal HVA. The viewing angle switching signal HVA is a control signal sent by the host representing the viewing angle mode selected by the user. The digital-to-analog converter 103 converts the corresponding digital signal Vd into an analog signal Va, and then amplifies the analog signal Va via the operational amplifier 104 to obtain an output voltage Vout in the form of a positive and negative voltage square wave. The driving circuit provides the output voltage Vout as a driving voltage to the dimming box 202, controls the dimming box 202 to adjust the viewing angle display mode, and controls the display panel 200 to switch to a wide viewing angle or a narrow viewing angle mode according to the different voltage amplitudes of the output voltage Vout. However, the MCU 102 and the DAC 103 occupy a large area, and a lot of time is required to debug the corresponding code of the MCU, resulting in high raw material costs for the PCBA, waste of manpower, and more resources consumed to generate driving voltages in the form of positive and negative voltage square waves. Therefore, the design cost of the current display device is very high and the design cycle is long. Utility Model Content

[0004] In view of this, an object of the present invention is to provide a driving circuit and a liquid crystal display device to solve the problems of the prior art.

[0005] According to one aspect of the utility model, a driving circuit is provided, connected to a display panel, the display panel includes a display box and a dimming box, the driving circuit provides a driving voltage to the dimming box, the driving circuit includes: a power supply, outputting a power supply voltage and a plurality of DC voltages from different ports, respectively, the plurality of DC voltages including a first voltage, a second voltage, a third voltage, a fourth voltage, a fifth voltage and a sixth voltage; a timing controller, connected to the power supply to receive the power supply voltage and output a control signal; a selection circuit, connected to the power supply, receiving the third voltage, the fourth voltage, the fifth voltage, the sixth voltage and a viewing angle switching signal, outputting a first selection signal and a second selection signal, the voltage polarities of the first selection signal and the second selection signal being opposite and the absolute values ​​of the voltages being the same; and a square wave output circuit, connected to the power supply, the timing controller and the selection circuit, receiving the first voltage, the second voltage, the control signal, the first selection signal and the second selection signal, and providing an output voltage as the driving voltage to the display panel, wherein the control signal and the output voltage are both square wave signals, and the output voltage is a positive and negative voltage square wave signal formed by an alternating combination of the first selection signal and the second selection signal.

[0006] Optionally, the selection circuit includes: a first selection channel, connected to the power supply and the square wave output circuit, simultaneously receiving the third voltage, the fourth voltage and the perspective switching signal, and outputting the first selection signal to the square wave output circuit; and a second selection channel, connected to the power supply and the square wave output circuit, simultaneously receiving the fifth voltage, the sixth voltage and the perspective switching signal, and outputting the second selection signal to the square wave output circuit.

[0007] Optionally, the first selection channel outputs one of the third voltage and the fourth voltage as the first selection signal, and the second selection channel outputs one of the fifth voltage and the sixth voltage as the second selection signal.

[0008] Optionally, the power supply includes a power supply and a voltage-dividing resistor, the power supply includes a voltage source or a current source, and the voltage-dividing resistor includes a resistance voltage-dividing network or a sliding rheostat.

[0009] Optionally, the square wave output circuit includes: a first transistor, the source of the first transistor is grounded, the drain receives the first voltage, the gate receives the control signal, and the first intermediate voltage is provided from the drain of the first transistor; a second transistor, the source of the second transistor is grounded, the drain receives the second voltage, the gate receives the first intermediate voltage, and the second intermediate voltage is provided from the drain of the second transistor; a third transistor, the source of the third transistor receives the first selection signal, the drain is connected to the first end of the first resistor, and the gate receives the first intermediate voltage; and a fourth transistor, the source of the fourth transistor receives the second selection signal, the drain is connected to the second end of the first resistor, the gate receives the second intermediate voltage, and the second end of the first resistor provides the output voltage.

[0010] Optionally, the first transistor, the second transistor, the third transistor and the fourth transistor are all NMOS transistors.

[0011] Optionally, the first selection channel and the second selection channel both receive a viewing angle switching signal in a first level state in the first viewing angle mode of the display panel, and output the third voltage and the fifth voltage respectively; the first selection channel and the second selection channel both receive a viewing angle switching signal in a second level state in the second viewing angle mode of the display panel, and output the fourth voltage and the sixth voltage respectively.

[0012] Optionally, the first voltage is a positive voltage, the second voltage is a negative voltage, and the absolute values ​​of the first voltage and the second voltage are the same; the absolute values ​​of the third voltage and the fifth voltage are the same, and the voltage polarities are opposite; the absolute values ​​of the fourth voltage and the sixth voltage are the same, and the voltage polarities are opposite, and the absolute value of the third voltage is greater than the absolute value of the fourth voltage.

[0013] Optionally, the driving circuit further includes: an amplifier circuit connected to the square wave output circuit and the display panel, receiving the output voltage, and providing an amplified signal as a driving signal to the display panel, wherein the amplifier circuit includes an operational amplifier.

[0014] According to another aspect of the utility model, there is provided a liquid crystal display device, comprising: a display panel, the display panel comprising a stacked display box and a dimming box, the dimming box controlling the viewing angle mode of the display panel; and the above-mentioned driving circuit, the driving circuit being connected to the dimming box and providing an output voltage to the dimming box as a driving voltage of the dimming box.

[0015] The driving circuit and liquid crystal display device provided by the utility model provide a basic voltage for the square wave output circuit by a power supply and a timing controller, and then the selection circuit provides a first selection signal and a second selection signal for the square wave output circuit. The square wave output circuit combines the first selection signal and the second selection signal into an output voltage to obtain the positive and negative voltage square wave signal required by the dimming box. The entire driving circuit has a simple structure, convenient control, and a small size, thereby reducing costs and reducing the area of ​​the printed circuit board.

[0016] Furthermore, the square wave output circuit is composed of four transistors and a resistor, and the circuit connection is simple. Only four transistors can cooperate to output the required square wave signal in the working state, which is efficient and convenient, greatly reducing the cost and occupied area of ​​the circuit. It can more conveniently control the driving voltage of the dimming box, and further more conveniently control the viewing angle switching of the liquid crystal display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings.

[0018] Figure 1 A schematic structural block diagram of a driving circuit of an existing display device is shown;

[0019] Figure 2 A schematic structural block diagram of a driving circuit and a liquid crystal display device according to an embodiment of the utility model is shown;

[0020] Figure 3 Shown according to Figure 2 A schematic circuit diagram of a driving circuit;

[0021] Figure 4a and Figure 4b Schematic waveform diagrams of various signals generated by the square wave output circuit according to the embodiment of the utility model when the selection circuit outputs different voltages are respectively shown. DETAILED DESCRIPTION

[0022] Various embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by the same or similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale.

[0023] It should be understood that when describing the structure of a device, when a layer or a region is referred to as being "on" or "above" another layer or another region, it may mean being directly above the other layer or another region, or having other layers or regions between it and the other layer or another region. And if the device is turned over, the layer or a region will be "below" or "beneath" the other layer or another region. If it is to describe the situation of being directly above another layer or another region, this article will use the expression "A is directly above B" or "A is above B and adjacent to it".

[0024] The utility model improves the traditional driving circuit and provides another driving circuit and a liquid crystal display device including the driving circuit. Figure 2-4b introduce.

[0025] Figure 2 A schematic structural block diagram of a driving circuit and a liquid crystal display device according to an embodiment of the utility model is shown.

[0026] like Figure 2 As shown, the liquid crystal display device 20 of the utility model includes a driving circuit 300 and a display panel 200, and the display panel 200 can switch between wide and narrow viewing angles. The display panel 200 includes a dimming box 202 and a display box 201 that are stacked on each other. The dimming box 202 is arranged above the display box 201, that is, the dimming box 202 is located on the light-emitting side of the display box 201. The dimming box 202 is used to control the viewing angle of the display panel 200, and the display box 201 is used to control the display panel 200 to display a normal picture. Of course, the dimming box 202 can also be arranged below the display box 201, that is, on the light-incoming side of the display box 201. The display box 201 is preferably a liquid crystal box, and of course it can also be a self-luminous display (such as an OLED display, a Micro LED display, etc.). The driving circuit 300 is connected to the dimming box 202 and provides an output voltage Vout as a driving voltage of the dimming box. The dimming box 202 controls the display viewing angle of the display panel 200 according to the driving voltage to switch between a wide viewing angle display mode and a narrow viewing angle display mode.

[0027] like Figure 2, the driving circuit 300 includes a power supply 310, a timing controller 320, a square wave output circuit 330 and a selection circuit 340. The power supply 310 is, for example, a Power IC, including multiple output ports, and different voltages can be output from different output ports. For example, the power supply voltage VDD, the first voltage VD1, the second voltage VD2, the third voltage VD3, the fourth voltage VD4, the fifth voltage VD5 and the sixth voltage VD6 are output respectively. The voltage output by the power supply 310 can be a DC voltage with a fixed voltage value, which can be a positive voltage or a negative voltage. For example, the first voltage VD1 is a positive voltage, the second voltage VD2 is a negative voltage, and the absolute values ​​of the first voltage VD1 and the second voltage VD2 are the same. The absolute values ​​of the third voltage VD3 and the fifth voltage VD5 are the same, and the voltage polarities are opposite; the absolute values ​​of the fourth voltage VD4 and the sixth voltage VD6 are the same, and the voltage polarities are opposite. The absolute value of the first voltage VD1 may be greater than the absolute value of the third voltage VD3, and the absolute value of the third voltage VD3 is greater than the absolute value of the fourth voltage VD4. The first voltage VD1 to the sixth voltage VD6 are, for example, 8V, -8V, 5.2V, 2.6V, -5.2V and -2.6V, respectively. The timing controller 320 (TCON) is connected to the power supply 310 to receive the power supply voltage VDD and generate a control signal Vct1 accordingly. The timing controller 320 provides a control signal Vct1 to the square wave output circuit 330 connected thereto. The control signal Vct1 is, for example, a square wave signal, and its duty cycle is, for example, 50%. The control signal Vct1 is, for example, a square wave signal of 0-3V.

[0028] The selection circuit 340 is connected to the power supply 310 to receive the third voltage VD3, the fourth voltage VD4, the fifth voltage VD5 and the sixth voltage VD6. The selection circuit 340 can also receive the viewing angle switching signal HVA provided by the host, which is used as a control signal to represent the viewing angle mode that the user wants to switch to. The user selects different viewing angle modes, corresponding to the viewing angle switching signal HVA with different voltage values. The selection circuit 340 outputs different first selection signals and second selection signals according to the received viewing angle switching signal HVA. The selection circuit 340 further includes a first selection channel 341 and a second selection channel 342. The first selection channel 341 is connected to the power supply 310 and the square wave output circuit 330, and receives the third voltage VD3, the fourth voltage VD4 and the viewing angle switching signal HVA at the same time, so as to output the first selection signal to the square wave output circuit 330; the second selection channel 342 is connected to the power supply 310 and the square wave output circuit 330, and receives the fifth voltage VD5, the sixth voltage VD6 and the viewing angle switching signal HVA at the same time, and outputs the second selection signal to the square wave output circuit 330. For example, the first selection channel 341 outputs one of the third voltage VD3 and the fourth voltage VD4 as the first selection signal, and the second selection channel 342 outputs one of the fifth voltage VD5 and the sixth voltage VD6 as the second selection signal. That is, the first selection channel 341 selects to output the third voltage VD3 or the fourth voltage VD4 according to the level state of the viewing angle switching signal HVA, and the second selection channel 342 selects to output the fifth voltage VD5 or the sixth voltage VD6 according to the level state of the viewing angle switching signal HVA. The voltage polarities of the first selection signal and the second selection signal output by the first selection channel 341 and the second selection channel 342 are opposite, and the absolute values ​​of the voltages are the same. That is, when the first selection channel 341 outputs the third voltage VD3 (for example, 5.2V) as the first selection signal, the second selection channel 342 outputs the fifth voltage VD5 (-5.2V) as the second selection signal; and when the first selection channel 341 outputs the fourth voltage VD4 (for example, 2.6V) as the first selection signal, the second selection channel 342 outputs the sixth voltage VD6 (-2.6V) as the second selection signal.

[0029] The viewing angle switching signal HVA is a control signal of the selection circuit 340, which is generated by the host according to the user's selection, and corresponds to different voltage values ​​in different viewing angle modes. That is, the level state of the viewing angle switching signal HVA is divided into a high level and a low level. The first selection channel 341 and the second selection channel 342 both receive the viewing angle switching signal HVA in the first level state in the first viewing angle mode of the display panel 200 selected by the user, and output the third voltage VD3 and the fifth voltage VD5 respectively; the first selection channel 341 and the second selection channel 342 both receive the viewing angle switching signal HVA in the second level state in the second viewing angle mode of the display panel 200 selected by the user, and output the fourth voltage VD4 and the sixth voltage VD6 respectively. The first viewing angle mode and the second viewing angle mode are, for example, a wide viewing angle display mode (WVA, Wide Viewing Angle) and a narrow viewing angle display mode (NVA, Narrow Viewing Angle), respectively, then the first level state and the second level state correspond to a low level and a high level, respectively.

[0030] The square wave output circuit 330 is connected to the power supply 310, the timing controller 320 and the selection circuit 340 to receive the first voltage VD1, the second voltage VD2, the control signal Vct1, the first selection signal and the second selection signal, so as to provide the display panel 200 with an output voltage Vout as a driving voltage, and the output voltage Vout is a square wave signal, and the voltage value matches the first selection signal and the second selection signal. The square wave output circuit 330, for example, outputs a square wave signal formed by the alternating combination of the first selection signal and the second selection signal as the output voltage Vout. Then, in the wide viewing angle display mode, the first selection signal and the second selection signal are respectively the third voltage VD3 (5.2V) and the fifth voltage VD5 (-5.2V), and the output voltage Vout is a square wave signal of -5.2V-5.2V. In the narrow viewing angle display mode, the first selection signal and the second selection signal are respectively the fourth voltage VD4 (2.6V) and the sixth voltage VD6 (-2.6V), and the output voltage Vout is a square wave signal of -2.6V-2.6V.

[0031] Furthermore, the driving circuit of this embodiment may also include an amplifier circuit 350, which is connected to the square wave output circuit 330 and the display panel 200, receives the output voltage Vout, and provides an amplified signal Vop as a driving signal to the display panel 200, that is, the amplifier circuit 350 is used to amplify the output signal Vout and provide it to the display panel 200.

[0032] The driving circuit 300 of this embodiment may be located on a printed circuit board PCBA, and the printed circuit board may also include other driving circuits, such as a source driver and a gate driver, which are not shown here one by one.

[0033] Figure 3 Shown according to Figure 2 Schematic circuit diagram of the driving circuit.

[0034] Combination Figure 2 and Figure 3 , the selection circuit 340 includes a first selection channel 341 and a second selection channel 342. The first selection channel 341 and the second selection channel 342 each include three input terminals and one output terminal. The three input terminals and one output terminal are NC, NO, IN and COM respectively. The NC terminal and the NO terminal of the first selection channel 341 receive the third voltage VD3 and the fourth voltage VD4 respectively, the IN terminal receives the viewing angle switching signal HVA through the driver U3, and the COM terminal outputs the first selection signal (VD3 / VD4). For example, there is a single-pole double-throw switch between the NC terminal, the NO terminal and the COM terminal, and the viewing angle switching signal HVA is used to control the state of the switch. When the display panel 200 needs to display a wide viewing angle, the viewing angle switching signal HVA is low, the switch connects the NC terminal and the COM terminal, and the first selection signal is the third voltage VD3; when the display panel 200 needs to display a narrow viewing angle, the viewing angle switching signal HVA is high, the switch connects the NO terminal and the COM terminal, and the first selection signal is the fourth voltage VD4. Similarly, the NC terminal and the NO terminal of the second selection channel 342 receive the fifth voltage VD5 and the sixth voltage VD6 respectively, the IN terminal receives the viewing angle switching signal HVA through the driver U4, and the COM terminal outputs the second selection signal (VD5 / VD6). When the display panel 200 needs to display a wide viewing angle, the viewing angle switching signal HVA is low, the switch connects the NC terminal and the COM terminal, and the second selection signal is the fifth voltage VD5; when the display panel 200 needs to display a narrow viewing angle, the viewing angle switching signal HVA is high, the switch connects the NO terminal and the COM terminal, and the second selection signal is the sixth voltage VD6.

[0035] The power supply 310 includes, for example, a power supply and a voltage-dividing resistor. The power supply may be a voltage source or a current source. The voltage-dividing resistor may be a resistor voltage-dividing network composed of a plurality of resistors or a sliding variable resistor, etc. For example, the power supply U1 is connected in parallel with the voltage-dividing resistor R1, and one end of the parallel connection is grounded. A first voltage VD1 is provided from the voltage-dividing resistor R1. The first voltage VD1 may be 10V or 8V or other required voltage. The power supply U2 is connected in parallel with the voltage-dividing resistor R2, and one end of the parallel connection is grounded. A second voltage VD2 is provided from the voltage-dividing resistor R2. The first voltage VD2 may be -10V or -8V or other required voltage. Of course, the power supply 310 may also include a combination of a plurality of similar voltage sources and voltage-dividing resistors to generate the first voltage VD1 to the sixth voltage VD6, respectively. Figure 3Of course, other connection modes can be selected to output the first voltage VD1 to the sixth voltage VD6, which are not limited here.

[0036] The square wave output circuit 330 may include a first transistor M1, a second transistor M2, a third transistor M3 and a fourth transistor M4. The first transistor M1, the second transistor M2, the third transistor M3 and the fourth transistor M4 may all be NMOS transistors. The source of the first transistor M1 is grounded, the drain receives the first voltage VD1, the gate receives the control signal Vct1, and the first intermediate voltage VB1 is provided from the drain of the first transistor M1. The source of the second transistor M2 is grounded, the drain receives the second voltage VD2, the gate receives the first intermediate voltage VB1, and the second intermediate voltage VB2 is provided from the drain of the second transistor M2; the source of the third transistor M3 receives the first selection signal, the drain is connected to the first end of the first resistor R1, and the gate receives the first intermediate voltage VB1; the source of the fourth transistor M4 receives the second selection signal, the drain is connected to the second end of the first resistor R1, the gate receives the second intermediate voltage VB2, and the second end of the first resistor R1 provides the output voltage Vout. The timing controller 320 provides a square wave signal, which is equivalent to an AC source AC, connected between the gate of the first transistor M1 and the ground terminal, for example, providing a 0-3V square wave signal as the control signal Vct1. Then, when the first voltage VD1 is 10V and the control signal Vct1 is 3V, the first transistor M1 is turned on, and the first intermediate signal VB1 is grounded to 0V. When the control signal Vct1 is 0V, the first transistor M1 is turned off, and the potential of the first intermediate signal VB1 is also 10V, so the first intermediate signal is a square wave signal from 0V to 10V. The first intermediate signal VB1 controls the conduction state of the second transistor M2 and the third transistor M3. When the first intermediate signal VB1 is 10V, the second transistor M2 is turned on, the second intermediate signal VB2 is grounded to 0V, the third transistor M3 is turned on, and the fourth transistor M4 is turned off. At this time, the output voltage Vout is the first selection signal (VD3 / VD4); and when the first intermediate signal VB2 is 0V, the second transistor M3 is turned off, and the second intermediate signal VB3 has the same potential as the second voltage VD2, which is -10V. At this time, the third transistor M3 is turned off, and the fourth transistor M4 is turned on. At this time, the output voltage Vout is the second selection signal (VD5 / VD6). Therefore, the second intermediate signal VB2 is a square wave signal from -10V to 0V, and the output voltage Vout is a positive and negative voltage square wave signal composed of the first selection signal and the second selection signal alternately.

[0037] Therefore, the driving circuit 300 of the embodiment of the utility model is mainly provided with DC voltages (V3-V6) of different voltage values ​​by the power supply, and the DC voltage that can be received by the square wave output circuit 330 is controlled by the viewing angle switching signal HVA. The square wave output circuit 330 combines the two DC voltages, one positive and one negative, received under different viewing angle switching signals HVA into a positive and negative voltage square wave signal, and outputs it as an output voltage Vout. The square wave output circuit 330 is composed of only 4 transistors and a small amount of resistors, that is, the driving circuit 300 of the utility model mainly uses the square wave output circuit 330 to replace the MCU and DAC to generate positive and negative voltage square wave signals. The circuit structure composed of very simple components can achieve the same effect as the combination of MCU and DAC. The circuit design cost is greatly reduced and the circuit structure is simplified.

[0038] Figure 4a and Figure 4b Schematic waveform diagrams of various signals generated by the square wave output circuit according to the embodiment of the utility model when the selection circuit outputs different voltages are respectively shown.

[0039] Combination Figure 3 and Figure 4a , when the viewing angle switching signal HVA is at a low level, the first selection signal and the second selection signal are the third voltage VD3 and the fifth voltage VD5 respectively, and the third voltage VD3 and the fifth voltage VD5 are 5.2V and -5.2V respectively, the control signal Vct1 is a square wave of 0-3V, the first intermediate signal is a square wave of 0-10V, and the second intermediate signal VB2 is a square wave of -10V-0V. When the control signal Vct1 is 3V, the first transistor M1 is turned on, the first intermediate signal VB1 is 0V, the second transistor M2 and the third transistor M3 are turned off, the second intermediate signal is -10V, and the fourth transistor M4 is turned on. At this time, the output voltage Vout is the fifth voltage VD5, which is -5.2V. When the control signal Vct1 is 0 V, the first transistor M1 is turned off, the first intermediate signal VB1 is 10 V, the second transistor M2 and the third transistor M3 are turned on, the second intermediate signal is 0 V, and the fourth transistor M4 is turned off. At this time, the output voltage Vout is the third voltage VD3, which is 5.2 V. The final output voltage Vout is a square wave of ±5.2 V, driving the display panel 200 in the wide viewing angle display mode.

[0040] Combination Figure 3 and Figure 4b, when the viewing angle switching signal HVA is at a high level, the first selection signal and the second selection signal are respectively the fourth voltage VD4 and the sixth voltage VD6, and the fourth voltage VD4 and the sixth voltage VD6 are 2.6V and -2.6V respectively, the control signal Vct1 is a square wave of 0-3V, the first intermediate signal is a square wave of 0-10V, and the second intermediate signal VB2 is a square wave of -10V-0V. When the control signal Vct1 is 3V, the first transistor M1 is turned on, the first intermediate signal VB1 is 0V, the second transistor M2 and the third transistor M3 are turned off, the second intermediate signal is -10V, and the fourth transistor M4 is turned on. At this time, the output voltage Vout is the sixth voltage VD6, which is -2.6V. When the control signal Vct1 is 0 V, the first transistor M1 is turned off, the first intermediate signal VB1 is 10 V, the second transistor M2 and the third transistor M3 are turned on, the second intermediate signal is 0 V, and the fourth transistor M4 is turned off. At this time, the output voltage Vout is the fourth voltage VD4, which is 2.6 V. The final output voltage Vout is a square wave of ±2.6 V, driving the display panel 200 in the narrow viewing angle display mode.

[0041] The above driving circuit can easily obtain the output voltage of the square wave signal as the driving voltage, without the need to use circuits such as MCU and DAC, and without the need to perform MCU coding settings. This can greatly reduce the circuit design and construction costs, simplify the circuit structure, and reduce the design size of the PCBA.

[0042] In summary, the driving circuit and liquid crystal display device provided by the utility model provide a basic voltage for the square wave output circuit by the power supply and the timing controller, and then the selection circuit provides the first selection signal and the second selection signal for the square wave output circuit, and the square wave output circuit combines the first selection signal and the second selection signal into an output voltage to obtain the square wave signal required by the dimming box. The entire driving circuit has a simple structure, convenient control, and a small size, thereby reducing costs and reducing the area of ​​the printed circuit board.

[0043] Furthermore, the square wave output circuit is composed of four transistors and a resistor, and the circuit connection is simple. Only four transistors can cooperate to output the required square wave signal in the working state, which is efficient and convenient, greatly reducing the cost and occupied area of ​​the circuit. It can more conveniently control the driving voltage of the dimming box, and further more conveniently control the viewing angle switching of the liquid crystal display device.

[0044] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0045] Finally, it should be noted that: according to the embodiments of the present utility model as described above, these embodiments do not describe all the details in detail, nor do they limit the utility model to the specific embodiments described. Obviously, according to the above description, many modifications and changes can be made. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model. This specification selects and specifically describes this embodiment in order to better explain the principle and practical application of the utility model, so that technicians in the relevant technical field can make good use of the utility model and the modified use based on the utility model. The utility model is only limited by the claims and their full scope and equivalents.

Claims

1. A driving circuit connected to a display panel, wherein the display panel includes a display box and a dimming box, and the driving circuit provides a driving voltage to the dimming box, characterized in that: The driving circuit comprises: A power supply, which outputs a power supply voltage and a plurality of DC voltages from different ports, respectively, wherein the plurality of DC voltages include a first voltage, a second voltage, a third voltage, a fourth voltage, a fifth voltage and a sixth voltage; A timing controller, connected to the power supply to receive the power supply voltage and output a control signal; a selection circuit connected to the power supply, receiving the third voltage, the fourth voltage, the fifth voltage, the sixth voltage and the viewing angle switching signal, and outputting a first selection signal and a second selection signal, wherein the voltage polarities of the first selection signal and the second selection signal are opposite and the absolute values ​​of the voltages are the same; and a square wave output circuit, connected to the power supply, the timing controller and the selection circuit, receiving the first voltage, the second voltage, the control signal, the first selection signal and the second selection signal, and providing an output voltage as the driving voltage to the display panel, Wherein, the control signal and the output voltage are both square wave signals, and the output voltage is a positive and negative voltage square wave signal formed by an alternating combination of the first selection signal and the second selection signal.

2. The driving circuit according to claim 1, characterized in that: The selection circuit comprises: a first selection channel, connected to the power supply and the square wave output circuit, receiving the third voltage, the fourth voltage and the viewing angle switching signal at the same time, and outputting the first selection signal to the square wave output circuit; and The second selection channel is connected to the power supply and the square wave output circuit, receives the fifth voltage, the sixth voltage and the viewing angle switching signal at the same time, and outputs the second selection signal to the square wave output circuit.

3. The driving circuit according to claim 2, characterized in that: The first selection channel outputs one of the third voltage and the fourth voltage as the first selection signal, and the second selection channel outputs one of the fifth voltage and the sixth voltage as the second selection signal.

4. The driving circuit according to claim 1, characterized in that: The power supply includes a power supply and a voltage-dividing resistor. The power supply includes a voltage source or a current source. The voltage-dividing resistor includes a resistor voltage-dividing network or a sliding rheostat.

5. The driving circuit according to claim 2, characterized in that: The square wave output circuit comprises: a first transistor, wherein a source of the first transistor is grounded, a drain of the first transistor receives the first voltage, a gate of the first transistor receives the control signal, and a first intermediate voltage is provided from the drain of the first transistor; a second transistor, wherein a source of the second transistor is grounded, a drain of the second transistor receives the second voltage, a gate of the second transistor receives the first intermediate voltage, and the second intermediate voltage is provided from the drain of the second transistor; a third transistor, wherein a source of the third transistor receives the first selection signal, a drain of the third transistor is connected to the first end of the first resistor, and a gate of the third transistor receives the first intermediate voltage; and A fourth transistor, wherein a source of the fourth transistor receives the second selection signal, a drain of the fourth transistor is connected to the second end of the first resistor, a gate of the fourth transistor receives the second intermediate voltage, and the second end of the first resistor provides the output voltage.

6. The driving circuit according to claim 5, characterized in that: The first transistor, the second transistor, the third transistor and the fourth transistor are all NMOS transistors.

7. The driving circuit according to claim 3, characterized in that: The first selection channel and the second selection channel both receive a viewing angle switching signal in a first level state in the first viewing angle mode of the display panel, and output the third voltage and the fifth voltage respectively; the first selection channel and the second selection channel both receive a viewing angle switching signal in a second level state in the second viewing angle mode of the display panel, and output the fourth voltage and the sixth voltage respectively.

8. The driving circuit according to claim 7, characterized in that: The first voltage is a positive voltage, the second voltage is a negative voltage, and the absolute values ​​of the first voltage and the second voltage are the same; the absolute values ​​of the third voltage and the fifth voltage are the same, and the voltage polarities are opposite; the absolute values ​​of the fourth voltage and the sixth voltage are the same, and the voltage polarities are opposite, and the absolute value of the third voltage is greater than the absolute value of the fourth voltage.

9. The driving circuit according to claim 1, characterized in that: Also includes: The amplifier circuit is connected to the square wave output circuit and the display panel, receives the output voltage, and provides an amplified signal as a driving signal to the display panel. The amplifier circuit includes an operational amplifier.

10. A liquid crystal display device, characterized in that: include: A display panel, the display panel comprising a stacked display box and a dimming box, the dimming box controlling a viewing angle mode of the display panel; as well as According to any one of claims 1 to 9, the driving circuit is connected to the dimming box and provides an output voltage to the dimming box as a driving voltage of the dimming box.

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