A hardware drive circuit for multi-segment digital LCD liquid crystal screen

Abstract

The application discloses a kind of hardware drive circuit of multi-segment number LCD liquid crystal screen, belong to liquid crystal display technical field.The drive circuit of the application is mainly composed of LCD drive-COM module, LCD drive-SEG module, backlight drive module, master control single-chip module, each module is connected liquid crystal screen by FPC terminal.The single-chip microcomputer I / O resource of the liquid crystal screen driven by the application is not limited;According to different screen, the same circuit can be used for driving, and the single-chip microcomputer with different pins is used, and the single-chip microcomputer resource is more flexible to use;It can get rid of the limitation that only single-chip microcomputer with LCD drive function can be used;Single-chip microcomputer is more free, and single-chip microcomputer with more function peripherals can be used;Control is more accurate, especially in driving multi-segment liquid crystal screen, more than one single-chip microcomputer drive, display drive algorithm is more simple;SEG and COM drive voltage can be changed by peripheral circuit.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal display technology, specifically relating to a hardware driving circuit for a multi-segment LCD screen. Background Technology

[0002] With the continuous upgrading of display devices, various display methods have gradually become more widespread. VA panels are a type of display material that uses the rotation of liquid crystals to adjust the amount of LED backlight transmission, thereby achieving display. Currently, most VA LCD panels are driven by microcontrollers with LCD driving capabilities, which control the screen's operating state through special pins. When using a microcontroller with LCD driving capabilities to drive the screen, there is a limitation: the microcontroller's resources are insufficient to drive all the liquid crystal segments, requiring multiple microcontrollers to control simultaneously. Due to the differences between each microcontroller, there is a risk of display delay or asynchrony, affecting the stability of the entire display system.

[0003] Furthermore, a microcontroller with an LCD driver must be used, which limits the diversity of microcontroller choices and occupies the use of other functions such as serial ports. Summary of the Invention

[0004] In view of the above-mentioned technical problems in the prior art, the present invention proposes a hardware driving circuit for a multi-segment LCD screen. The circuit is reasonably designed, overcomes the shortcomings of the prior art, and has good performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A hardware driving circuit for a multi-segment LCD screen includes:

[0007] The main control microcontroller module is configured to output SEG and COM signals to drive the LCD screen;

[0008] The LCD driver-COM module is connected to the I / O port of the main control microcontroller module and is configured to convert the COM signal output by the microcontroller into the COM segment voltage required to drive the LCD screen through resistors, capacitors and MOSFETs, and output it to the COM terminal of the LCD screen.

[0009] The LCD driver-SEG module is connected to the I / O port of the main control microcontroller module and is configured to convert the SEG signal output by the microcontroller into the SEG segment voltage required to drive the LCD screen through resistors and capacitors, and output it to the SEG terminal of the LCD screen.

[0010] The backlight driver module provides backlight power to the LCD screen.

[0011] The LCD driver-COM module and the SEG driver module generate the voltage difference required by the LCD screen through their respective voltage divider circuits, and control the rotation of the LCD screen to achieve display.

[0012] Preferably, the LCD driver-COM module includes:

[0013] The complementary square wave generation circuit is configured to receive complementary square wave signals from the main control microcontroller module;

[0014] The first voltage divider circuit is connected to the complementary square wave generation circuit via a line. It divides the complementary square wave signal using resistors, capacitors, and MOSFETs to generate a three-segment voltage, which controls the display on the LCD screen.

[0015] Preferably, the complementary square wave generating circuit includes a first resistor R39, a second resistor R40, a third resistor R22, a fourth resistor R30, a fifth resistor R14, a sixth resistor R54, a first capacitor C4, a second capacitor C6, a first transistor Q6, a first MOSFET Q4, and a second MOSFET Q8.

[0016] One end of the first resistor R39 and one end of the second resistor R40 form a common terminal that is connected to the base of the first transistor Q6;

[0017] One end of the third resistor R22 and one end of the fourth resistor R30 form a common terminal that is connected to the collector of the first transistor Q6;

[0018] The other end of the fourth resistor R30 and one end of the first capacitor C4 form a common terminal that is connected to the gate of the first MOSFET Q4;

[0019] The other end of the second resistor R40, the other end of the first capacitor C4, and the emitter of the first transistor Q6 form a common terminal connected to ground;

[0020] One end of the fifth resistor R14 is connected to the source of the first MOSFET Q4;

[0021] The other end of the fifth resistor R14 and the other end of the third resistor R22 form a common terminal that is connected to the power supply.

[0022] One end of the sixth resistor R54 and one end of the second capacitor C6 form a common terminal that is connected to the gate of the second MOSFET Q8;

[0023] The drain of the first MOSFET Q4 is connected to the drain of the second MOSFET Q8;

[0024] The other end of the second capacitor C6 and the source of the second MOSFET Q8 form a common terminal connected to ground.

[0025] Preferably, the first voltage divider circuit includes a seventh resistor R25, an eighth resistor R15, a ninth resistor R41, a tenth resistor RL2, an eleventh resistor R49, a third capacitor C2, and a third MOSFET Q3.

[0026] One end of the seventh resistor R25, one end of the eighth resistor R15, and one end of the third capacitor C2 form a common terminal that is connected to the gate of the third MOSFET Q3;

[0027] The other end of the third capacitor C2 is grounded;

[0028] The source of the third MOSFET Q3 and the other end of the eighth resistor R15 form a common terminal connected to the power supply.

[0029] The tenth resistor RL2 and the eleventh resistor R49 form a parallel circuit. One end of the parallel circuit and one end of the ninth resistor R41 form a common terminal connected to the drain of the second MOSFET Q8. The other end of the ninth resistor R41 is connected to the drain of the third MOSFET Q3. The other end of the parallel circuit is connected to the source of the second MOSFET Q8.

[0030] Preferably, the LCD driver-SEG module includes:

[0031] The second voltage divider circuit is connected to the I / O port of the main control microcontroller module. It divides the SEG signal from the main control microcontroller through resistors and capacitors to generate a three-segment voltage, which, together with the COM voltage, controls the display of the LCD screen.

[0032] Preferably, the second voltage divider circuit includes a twelfth resistor R1, a thirteenth resistor R3, and a fourth capacitor EC1;

[0033] One end of the twelfth resistor R1 is connected to one end of the thirteenth resistor R3, the other end of the thirteenth resistor R3 is connected to the positive terminal of the fourth capacitor EC1, and the negative terminal of the fourth capacitor EC1 is connected to ground.

[0034] Preferably, the main control microcontroller module is a general-purpose microcontroller, and the number of its I / O ports is expanded according to the segment requirements of the LCD screen.

[0035] Preferably, the voltage values ​​of the LCD driver-COM module and the LCD driver-SEG module are adapted by adjusting the resistance value of the voltage divider resistor or the capacitance value.

[0036] Preferably, the backlight driving module provides a constant current or a constant voltage to the LCD screen.

[0037] Preferably, the LCD driver-COM module, LCD driver-SEG module, backlight driver module, and main control microcontroller module are connected via FPC terminals.

[0038] The beneficial technical effects of this invention are as follows:

[0039] This invention provides unrestricted microcontroller I / O resources for driving LCD screens; the same circuit can be used to drive different screens, and microcontrollers with different pin configurations can be paired with it, making the use of microcontroller resources more flexible; it eliminates the limitation of only being able to use microcontrollers with LCD driving functions; the microcontroller is more flexible and can use microcontrollers with more functional peripherals; the control is more precise, especially when driving multi-segment LCD screens, and the display driving algorithm is simpler than using multiple microcontrollers; the driving voltages of SEG and COM can be changed through external circuits. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of a hardware driving circuit for a multi-segment LCD screen.

[0041] Figure 2 This is the schematic diagram of the LCD driver-COM1 module circuit.

[0042] Figure 3 Schematic diagram of LCD driver-COM2 module circuit;

[0043] Figure 4 Schematic diagram of LCD driver-COM3 module circuit;

[0044] Figure 5 Schematic diagram of LCD driver-COM4 module circuit;

[0045] Figure 6 This is the circuit schematic of the backlight driver module;

[0046] Figure 7 This is a schematic diagram of the main control microcontroller module. Detailed Implementation

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0048] The working principle of the hardware driver circuit for this multi-segment LCD screen is as follows:

[0049] Signal source:

[0050] The main control microcontroller (MCU) does not have LCD driving capabilities, but it generates the SEG and COM signals required to drive the LCD screen through its I / O ports. These signals are typically digital square wave signals used to control the display status of the LCD screen.

[0051] COM signal processing:

[0052] The COM signal from the MCU is sent to the LCD driver-COM module.

[0053] Complementary square wave generation circuit: Complementary square waves are generated in the COM module, for example, by switching a transistor or MOSFET to generate two square wave signals with opposite phases.

[0054] Voltage divider circuit: The complementary square wave is divided by a voltage divider circuit (composed of resistors, capacitors, MOSFETs, etc.) to generate a three-segment COM voltage. These three voltages are VCC, ground, and intermediate voltage, which are used to control the voltage of the common terminal (COM) of the LCD screen.

[0055] SEG signal processing:

[0056] The SEG signal from the MCU is sent to the LCD driver - SEG module.

[0057] Voltage divider circuit: The voltage divider circuit in the SEG module (composed of resistors, capacitors, etc.) divides the SEG signal, and also generates a three-segment SEG voltage (VCC, ground and intermediate voltage).

[0058] LCD driver:

[0059] Each segment of the LCD screen is controlled by a COM terminal and a SEG terminal.

[0060] By controlling the voltage difference between the COM and SEG terminals, the rotation of the liquid crystal molecules can be controlled, thereby controlling the display state of that segment. When the voltage difference between COM and SEG is large enough (greater than the saturation voltage), the liquid crystal molecules rotate, and that segment is displayed; when the voltage difference is small or zero (less than the threshold voltage), the liquid crystal molecules do not rotate, and that segment is not displayed.

[0061] Since the COM and SEG voltages are generated by external hardware circuits, a regular microcontroller without an LCD driver can be selected as the main controller, thus freeing up the limitations of microcontroller selection and allowing the use of more peripheral functions of the microcontroller.

[0062] By adjusting the parameters of the external circuit (such as the resistance value), the driving voltage of SEG and COM can be changed, thereby adapting to different specifications of LCD screens.

[0063] like Figure 1 As shown, a hardware driving circuit for a multi-segment LCD screen includes:

[0064] Main control microcontroller module (such as) Figure 7 As shown, it is configured to output SEG and COM signals to drive the LCD screen;

[0065] The LCD driver-COM module is connected to the I / O port of the main control microcontroller module and is configured to convert the COM signal output by the microcontroller into the COM segment voltage required to drive the LCD screen through resistors, capacitors and MOSFETs, and output it to the COM terminal of the LCD screen.

[0066] The LCD driver-SEG module is connected to the I / O port of the main control microcontroller module and is configured to convert the SEG signal output by the microcontroller into the SEG segment voltage required to drive the LCD screen through resistors and capacitors, and output it to the SEG terminal of the LCD screen.

[0067] The backlight driver module provides backlight power to the LCD screen.

[0068] The LCD driver-COM module and the SEG driver module generate the voltage difference required by the LCD screen through their respective voltage divider circuits, and control the rotation of the LCD screen to achieve display.

[0069] LCD driver-COM module includes (such as) Figure 2-5 As shown):

[0070] The complementary square wave generation circuit is configured to receive complementary square wave signals from the main control microcontroller module;

[0071] The first voltage divider circuit is connected to the complementary square wave generation circuit via a line. It divides the complementary square wave signal using resistors, capacitors, and MOSFETs to generate a three-segment voltage, which controls the display on the LCD screen.

[0072] The complementary square wave generation circuit includes a first resistor R39, a second resistor R40, a third resistor R22, a fourth resistor R30, a fifth resistor R14, a sixth resistor R54, a first capacitor C4, a second capacitor C6, a first transistor Q6, a first MOSFET Q4, and a second MOSFET Q8.

[0073] One end of the first resistor R39 and one end of the second resistor R40 form a common terminal that is connected to the base of the first transistor Q6;

[0074] One end of the third resistor R22 and one end of the fourth resistor R30 form a common terminal that is connected to the collector of the first transistor Q6;

[0075] The other end of the fourth resistor R30 and one end of the first capacitor C4 form a common terminal that is connected to the gate of the first MOSFET Q4;

[0076] The other end of the second resistor R40, the other end of the first capacitor C4, and the emitter of the first transistor Q6 form a common terminal connected to ground;

[0077] One end of the fifth resistor R14 is connected to the source of the first MOSFET Q4;

[0078] The other end of the fifth resistor R14 and the other end of the third resistor R22 form a common terminal that is connected to the power supply.

[0079] One end of the sixth resistor R54 and one end of the second capacitor C6 form a common terminal that is connected to the gate of the second MOSFET Q8;

[0080] The drain of the first MOSFET Q4 is connected to the drain of the second MOSFET Q8;

[0081] The other end of the second capacitor C6 and the source of the second MOSFET Q8 form a common terminal connected to ground.

[0082] The first voltage divider circuit includes the seventh resistor R25, the eighth resistor R15, the ninth resistor R41, the tenth resistor RL2, the eleventh resistor R49, the third capacitor C2, and the third MOSFET Q3.

[0083] One end of the seventh resistor R25, one end of the eighth resistor R15, and one end of the third capacitor C2 form a common terminal that is connected to the gate of the third MOSFET Q3;

[0084] The other end of the third capacitor C2 is grounded;

[0085] The source of the third MOSFET Q3 and the other end of the eighth resistor R15 form a common terminal connected to the power supply.

[0086] The tenth resistor RL2 and the eleventh resistor R49 form a parallel circuit. One end of the parallel circuit and one end of the ninth resistor R41 form a common terminal connected to the drain of the second MOSFET Q8. The other end of the ninth resistor R41 is connected to the drain of the third MOSFET Q3. The other end of the parallel circuit is connected to the source of the second MOSFET Q8.

[0087] The LCD driver-SEG module includes:

[0088] The second voltage divider circuit is connected to the I / O port of the main control microcontroller module. It divides the SEG signal from the main control microcontroller through resistors and capacitors to generate a three-segment voltage, which, together with the COM voltage, controls the display of the LCD screen.

[0089] The second voltage divider circuit is connected to the I / O port of the main control microcontroller module. It divides the SEG signal from the main control microcontroller through resistors and capacitors to generate a three-segment voltage, which, together with the COM voltage, controls the display of the LCD screen.

[0090] The main control microcontroller module is a general-purpose microcontroller, and the number of its I / O ports can be expanded according to the segment requirements of the LCD screen.

[0091] The voltage values ​​of the LCD driver-COM module and the LCD driver-SEG module are adapted by adjusting the resistance value of the voltage divider resistor or the capacitance value.

[0092] The backlight driver module provides a constant current or constant voltage to the LCD screen.

[0093] The LCD driver-COM module, LCD driver-SEG module, backlight driver module, and main control microcontroller module are connected via FPC terminals.

[0094] The details are as follows:

[0095] (1) COM Modules - Module 1

[0096] The microcontroller's I / O-1 port is connected to the left side of resistor R39, and the right side of resistor R39 is connected to the top side of resistor R49, with transistor Q6. The bottom side of resistor R49 is connected to ground. The top side of resistor R40 and the top side of transistor Q6 are connected to the bottom side of resistor R22, with the top side of resistor R22 connected to power supply VCC. The bottom side of Q6 is connected to ground. The top side of transistor Q6 is connected to the left side of resistor R30, and the right side of resistor R30 is connected to the top side of capacitor C4, with the bottom side of C4 connected to ground. The right side of resistor R30 is connected to MOSFET Q4, and the top side of Q4 is connected to the bottom side of resistor R14, with the top side of R14 connected to power supply VCC. The bottom side of Q4 is connected to the top side of MOSFET Q8. The microcontroller's I / O-2 port is connected to the left side of resistor R54, and the right side of resistor R54 is connected to the top side of capacitor C6, with the bottom side of capacitor C6 connected to ground. The right side of resistor R54 is connected to MOSFET Q8, with the bottom side of MOSFET Q8 connected to ground. The microcontroller's I / O-1 port is connected to the right side of resistor R25. The left side of resistor R25 is connected to the top of capacitor C22, and the bottom of C22 is connected to ground. The left side of resistor R25 is connected to the bottom of resistor R15, and the top of resistor R15 is connected to ground. The left side of resistor R25 is connected to MOSFET Q3. The top of Q3 is connected to power supply VCC, and the bottom of Q3 is connected to the top of resistor R41. The bottom of resistor R41 is connected to the top of resistors RL2 and R49, and the bottoms of resistors RL2 and R49 are connected to ground.

[0097] The LCD driving voltage is output from the COM1 network.

[0098] Complementary square waves are output through I / O-1 and I / O-2, and a three-segment voltage is generated through voltage division using a MOSFET and resistors. This voltage is then used in conjunction with SEG to control the LCD display.

[0099] COM modules 2, 3, and 4 are the same as COM module 1.

[0100] (2) SEG module

[0101] Connect the left side of resistor R1 to the I / O-3 port of the microcontroller, connect the right side of resistor R1 to the left side of R3, connect the right side of R3 to the top of capacitor EC1, and connect the bottom of capacitor EC1 to the power ground.

[0102] Through voltage division by resistors and capacitors, the SEG network outputs a three-segment voltage, which, in conjunction with the SEG voltage, controls the LCD display.

[0103] The above describes a single SEG driver; the same applies to multiple SEG drivers.

[0104] (3) The backlight driving module includes (such as...) Figure 6 As shown):

[0105] Power input terminal (VIN), overvoltage protection circuit (OVP), enable control terminal (EN), voltage regulator capacitors (C13-C16) and MOSFET switch;

[0106] The backlight voltage is adjusted by voltage divider resistors (R134, R135) and diode (D1) to provide a stable backlight power supply for the LCD screen.

[0107] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A hardware driving circuit for a multi-segment LCD screen, characterized in that, include: The main control microcontroller module is configured to output SEG and COM signals to drive the LCD screen; The LCD driver-COM module is connected to the I / O port of the main control microcontroller module and is configured to convert the COM signal output by the microcontroller into the COM segment voltage required to drive the LCD screen through resistors, capacitors and MOSFETs, and output it to the COM terminal of the LCD screen. The LCD driver-SEG module is connected to the I / O port of the main control microcontroller module and is configured to convert the SEG signal output by the microcontroller into the SEG segment voltage required to drive the LCD screen through resistors and capacitors, and output it to the SEG terminal of the LCD screen. The backlight driver module provides backlight power to the LCD screen. Among them, the LCD driver-COM module and the SEG driver module generate the voltage difference required by the LCD screen through their respective voltage divider circuits, and control the rotation of the LCD screen to achieve display. The LCD driver-COM module includes: The complementary square wave generation circuit is configured to receive complementary square wave signals from the main control microcontroller module; The first voltage divider circuit is connected to the complementary square wave generation circuit through a line. It divides the complementary square wave signal through resistors, capacitors and MOSFETs to generate a three-segment voltage to control the display of the LCD screen. The complementary square wave generation circuit includes a first resistor R39, a second resistor R40, a third resistor R22, a fourth resistor R30, a fifth resistor R14, a sixth resistor R54, a first capacitor C4, a second capacitor C6, a first transistor Q6, a first MOSFET Q4, and a second MOSFET Q8. One end of the first resistor R39 and one end of the second resistor R40 form a common terminal that is connected to the base of the first transistor Q6; One end of the third resistor R22 and one end of the fourth resistor R30 form a common terminal that is connected to the collector of the first transistor Q6; The other end of the fourth resistor R30 and one end of the first capacitor C4 form a common terminal that is connected to the gate of the first MOSFET Q4; The other end of the second resistor R40, the other end of the first capacitor C4, and the emitter of the first transistor Q6 form a common terminal connected to ground; One end of the fifth resistor R14 is connected to the source of the first MOSFET Q4; The other end of the fifth resistor R14 and the other end of the third resistor R22 form a common terminal that is connected to the power supply. One end of the sixth resistor R54 and one end of the second capacitor C6 form a common terminal that is connected to the gate of the second MOSFET Q8; The drain of the first MOSFET Q4 is connected to the drain of the second MOSFET Q8; The other end of the second capacitor C6 and the source of the second MOSFET Q8 form a common terminal connected to ground.

2. The hardware driving circuit for a multi-segment LCD screen according to claim 1, characterized in that, The first voltage divider circuit includes the seventh resistor R25, the eighth resistor R15, the ninth resistor R41, the tenth resistor RL2, the eleventh resistor R49, the third capacitor C2, and the third MOSFET Q3. One end of the seventh resistor R25, one end of the eighth resistor R15, and one end of the third capacitor C2 form a common terminal that is connected to the gate of the third MOSFET Q3; The other end of the third capacitor C2 is grounded; The source of the third MOSFET Q3 and the other end of the eighth resistor R15 form a common terminal connected to the power supply. The tenth resistor RL2 and the eleventh resistor R49 form a parallel circuit, with one end of the parallel circuit connected to one end of the ninth resistor R41. The common terminal is connected to the drain of the second MOSFET Q8, and the other end of the ninth resistor R41 is connected to the drain of the third MOSFET Q3; the other end of the parallel circuit is connected to the source of the second MOSFET Q8.

3. The hardware driving circuit for a multi-segment LCD screen according to claim 1, characterized in that, The LCD driver-SEG module includes: The second voltage divider circuit is connected to the I / O port of the main control microcontroller module. It divides the SEG signal from the main control microcontroller through resistors and capacitors to generate a three-segment voltage, which, together with the COM voltage, controls the display of the LCD screen.

4. The hardware driving circuit for a multi-segment LCD screen according to claim 3, characterized in that, The second voltage divider circuit includes the twelfth resistor R1, the thirteenth resistor R3, and the fourth capacitor EC1; One end of the twelfth resistor R1 is connected to one end of the thirteenth resistor R3, the other end of the thirteenth resistor R3 is connected to the positive terminal of the fourth capacitor EC1, and the negative terminal of the fourth capacitor EC1 is connected to ground.

5. The hardware driving circuit for a multi-segment LCD screen according to claim 1, characterized in that, The main control microcontroller module is a general-purpose microcontroller, and the number of its I / O ports can be expanded according to the segment requirements of the LCD screen.

6. The hardware driving circuit for a multi-segment LCD screen according to claim 1, characterized in that, The voltage values ​​of the LCD driver-COM module and the LCD driver-SEG module are adapted by adjusting the resistance value of the voltage divider resistor or the capacitance value.

7. The hardware driving circuit for a multi-segment LCD screen according to claim 1, characterized in that, The backlight driver module provides a constant current or constant voltage to the LCD screen.

8. The hardware driving circuit for a multi-segment LCD screen according to claim 1, characterized in that, The LCD driver-COM module, LCD driver-SEG module, backlight driver module, and main control microcontroller module are connected via FPC terminals.

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