Liquid crystal handwriting board and liquid crystal handwriting board system

Abstract

The liquid crystal handwriting board comprises an electric control module, a liquid crystal handwriting film, an electromagnetic antenna board and a handwriting substrate, the liquid crystal handwriting film, the electromagnetic antenna board and the handwriting substrate are sequentially arranged from top to bottom, and the electric control module comprises a power supply unit, a main control unit, an electromagnetic control unit, a liquid crystal driving unit and a data transmission unit. According to the liquid crystal handwriting board, on one hand, the electromagnetic control unit transmits acquired writing / erasing coordinate information to the intelligent display equipment through the data transmission unit, so that the intelligent display equipment synchronously displays writing / erasing handwriting; on the other hand, the electromagnetic control unit transmits the collected erasing coordinate information to the main control unit through the data transmission unit, so that the main control unit completes handwriting erasing by controlling the liquid crystal driving unit.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal writing tablets, and particularly to a liquid crystal writing tablet and a liquid crystal writing tablet system. Background Art

[0002] Most of the existing writing tablets that can be connected to a computer are electromagnetic writing tablets. When a user writes on the writing tablet, the computer can not only display the content written by the user on the writing tablet, but also store the content on the writing tablet for the user to call later.

[0003] However, since the electromagnetic writing tablet itself cannot display the content written by the user, during the process of using the electromagnetic writing tablet to write, the user's eyes need to always focus on the computer display screen, which is not convenient enough. Summary of the Invention

[0004] The main object of the present invention is to provide a liquid crystal writing tablet and a liquid crystal writing tablet system, aiming to solve the current technical problems.

[0005] To achieve the above object, the present invention provides a liquid crystal writing tablet, including an electronic control module, a liquid crystal writing film, an electromagnetic antenna board, and a writing substrate sequentially arranged from top to bottom. The electronic control module includes a power supply unit, a main control unit, an electromagnetic control unit, a liquid crystal driving unit, and a data transmission unit. The power supply terminals of the electromagnetic control unit, the data transmission unit, the main control unit, and the liquid crystal driving unit are all connected to the power supply unit. The data acquisition terminal of the electromagnetic control unit is connected to the electromagnetic antenna board. The output terminal of the electromagnetic control unit is connected to the input terminal of the data transmission unit. The first output terminal of the data transmission unit is connected to the first input terminal of the main control unit. The control terminal of the main control unit is connected to the controlled terminal of the liquid crystal driving unit. The output terminal of the liquid crystal driving unit is connected to the liquid crystal writing film. Wherein, the data transmission unit further includes a second output terminal for connecting to an intelligent display device. When the user performs a writing or erasing action on the liquid crystal writing tablet, the data transmission unit transmits a signal corresponding to the writing or erasing action to the intelligent display device, so that the intelligent display device responds to the writing or erasing action.

[0006] Preferably, the liquid crystal driving unit includes a negative voltage pre-generation circuit, a negative voltage generation circuit, a bias voltage generation circuit, a horizontal liquid crystal driving circuit, and a vertical liquid crystal driving circuit. The controlled end of the negative voltage pre-generation circuit is connected to the main control unit. The output end of the negative voltage pre-generation circuit is connected to the input end of the negative voltage generation circuit. The output end of the negative voltage generation circuit is connected to the output end of the bias voltage generation circuit. The first output end of the bias voltage generation circuit is connected to the input end of the horizontal liquid crystal driving circuit. The second output end of the bias voltage generation circuit is connected to the input end of the vertical liquid crystal driving circuit. The controlled end of the vertical liquid crystal driving circuit is connected to the main control unit. The horizontal liquid crystal driving circuit is used to output a horizontal driving voltage to the liquid crystal writing film, and the vertical liquid crystal driving circuit is used to output a vertical driving voltage to the liquid crystal writing film.

[0007] Preferably, the negative voltage pre-generation circuit includes a resistor R11, a resistor R12, a capacitor EC2, and N parallel-connected negative voltage control circuits. The controlled ends of each negative voltage control circuit are respectively connected to the main control unit. The feedback output ends of each negative voltage control circuit, the second end of the resistor R11, and the first end of the resistor R12 are connected to the feedback end of the negative voltage generation circuit. The output ends of each negative voltage control circuit, the second end of the resistor R12, and the first end of the capacitor EC2 are interconnected, and the connection node is the output end of the negative voltage pre-generation circuit. The first end of the resistor R11 and the second end of the capacitor EC2 are grounded, and N≥2.

[0008] Preferably, the negative voltage control circuit includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a transistor Q1, a transistor Q2, and a transistor Q3. The gate of the transistor Q1 is connected to the first end of the resistor R1, and the connection node is the controlled end of the negative voltage control circuit. The drain of the transistor Q1, the gate of the transistor Q2, and the second end of the resistor R2 are interconnected. The drain of the transistor Q2 is connected to the first end of the resistor R2. The second end of the resistor R3, the first end of the resistor R4, and the gate of the transistor Q3 are interconnected. The drain of the transistor Q3 is connected to the first end of the resistor R5, and the second end of the resistor R5 is the feedback output end of the negative voltage control circuit. The source of the transistor Q3 is connected to the second end of the resistor R4, and the connection node is the output end of the negative voltage control circuit. The source of the transistor Q2 and the first end of the resistor R2 are both connected to the power supply VCC, and the source of the transistor Q1 and the second end of the resistor R1 are both grounded.

[0009] Preferably, the liquid crystal handwriting film includes an upper conductive layer, a liquid crystal layer, and a lower conductive layer arranged in sequence from top to bottom. The upper conductive layer includes X horizontal conductive regions and Y vertical conductive regions. Each of the horizontal conductive regions is perpendicular to each of the vertical conductive regions. The lower conductive layer includes X horizontal conductive regions and Y vertical conductive regions corresponding to the upper conductive layer.

[0010] Preferably, the data transmission unit includes a Bluetooth control circuit and a Bluetooth antenna. The input end of the Bluetooth control circuit is the input end of the data transmission unit. The first output end of the Bluetooth control circuit is the first output end of the data transmission unit. The second output end of the Bluetooth control circuit is connected to the Bluetooth antenna, and the Bluetooth antenna is the second output end of the data transmission unit.

[0011] Preferably, the Bluetooth control circuit includes a Bluetooth chip control circuit. The data transmission unit further includes a display screen. The input end of the Bluetooth chip control circuit is the input end of the Bluetooth control circuit. The first output end of the Bluetooth chip control circuit is the first output end of the Bluetooth control circuit. The second output end of the Bluetooth chip control circuit is the second output end of the Bluetooth control circuit. The third output end of the Bluetooth chip control circuit is connected to the display screen.

[0012] Preferably, the electronic control module further includes a temperature sensor circuit. The output end of the temperature sensor circuit is connected to the second input end of the main control unit.

[0013] To achieve the above object, the present invention further provides a liquid crystal writing board system, including the liquid crystal writing board as described above and a writing pen adapted to the liquid crystal writing board. A writing / erasing mode selection button is provided on the writing pen.

[0014] Preferably, the liquid crystal writing board system further includes an intelligent display device adapted to the liquid crystal writing board. A writing pen / mouse mode selection button is also provided on the writing pen.

[0015] Compared with the existing ordinary electromagnetic writing board, the beneficial effects of the technical solution of the present invention are as follows:

[0016] On the one hand, by adding a liquid crystal handwriting film, the function of displaying handwriting on the writing board is realized. When the user writes on the writing board, the writing board can display the content written by the user, and there is no need to always focus on the computer screen.

[0017] On the other hand, by setting a Bluetooth control circuit and a Bluetooth antenna in the writing board, the wireless transmission of the writing / erasing handwriting information of the writing board to the intelligent display device is realized, avoiding the limitation of the connecting line when the user uses the writing board.

[0018] On the other hand, by providing X horizontal conductive regions and Y vertical conductive regions on the conductive layer of the liquid crystal writing film, and providing X horizontal conductive regions and Y vertical conductive regions corresponding to the upper conductive layer on the lower conductive layer of the liquid crystal writing film, the local erasing function of the writing board is realized.

[0019] This liquid crystal writing board can display the writing traces of users, transmit the writing / erasing information to the intelligent display device without wires, enable the intelligent display device to respond to the writing / erasing information, and can realize the local erasing function, which is very convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of an embodiment of the liquid crystal writing board of the present invention;

[0021] Figure 2 is Figure 1 a schematic diagram of the functional modules of an embodiment of the electronic control module in

[0022] Figure 3 It is a schematic structural diagram of another embodiment of the liquid crystal writing board of the present invention;

[0023] Figure 4 It is a schematic structural diagram of yet another embodiment of the liquid crystal writing board of the present invention;

[0024] Figure 5 It is a schematic structural diagram of still another embodiment of the liquid crystal writing board of the present invention;

[0025] Figure 6 is Figure 1 a schematic structural diagram of an embodiment of the liquid crystal writing film in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Next, the solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0027] Please refer to Figure 1 and Figure 2, the present invention provides a liquid crystal writing board, which includes an electric control module 500, a liquid crystal writing film 200, an electromagnetic antenna board 300, and a writing substrate 400 arranged in sequence from top to bottom. The electric control module 500 includes a power supply unit 510, a main control unit 540, an electromagnetic control unit 520, a liquid crystal driving unit 550, and a data transmission unit 530. The power supply terminals of the electromagnetic control unit 520, the data transmission unit 530, the main control unit 540, and the liquid crystal driving unit 550 are all connected to the power supply unit 510. The data acquisition terminal of the electromagnetic control unit 520 is connected to the electromagnetic antenna board 300. The output terminal of the electromagnetic control unit 520 is connected to the input terminal of the data transmission unit 530. The first output terminal of the data transmission unit 530 is connected to the first input terminal of the main control unit 540. The control terminal of the main control unit 540 is connected to the controlled terminal of the liquid crystal driving unit 550. The output terminal of the liquid crystal driving unit 550 is connected to the liquid crystal writing film 200.

[0028] Among them, the data transmission unit 530 further includes a second output terminal for connecting to an intelligent display device 600. When the user performs a writing or erasing action on the liquid crystal writing board, the data transmission unit 530 transmits a signal corresponding to the writing or erasing action to the intelligent display device 600, so that the intelligent display device 600 responds to the writing or erasing action.

[0029] Here, the specific position of the electric control module 500 can be set according to the user's needs or preferences, and no limitation is made here. For example, under the same writing area, if the user hopes that the size of the liquid crystal writing board is as small as possible, the electric control module 500 can be set below the writing substrate 400 to avoid occupying the side position of the liquid crystal writing film 200 and increasing the size of the liquid crystal writing board. If the user hopes that the liquid crystal writing board is as thin as possible, the electric control module 500 can be set on the side of the liquid crystal writing film 200 to avoid the electric control module 500 increasing the thickness of the liquid crystal writing board.

[0030] The power supply unit 510 includes a charging interface 511, a storage battery 512, and a power conversion circuit 513. When the liquid crystal writing board is connected to an external power supply, on the one hand, the storage battery 512 obtains the external power supply through the charging interface 511 for charging; on the other hand, the power conversion circuit 513 converts the external power supply into a power supply voltage adapted to each functional unit in the electric control module 500 to supply power to each functional unit. When the liquid crystal writing board is disconnected from the external power supply, the power conversion circuit 513 converts the power output by the storage battery 512 into a power supply voltage adapted to each functional unit in the electric control module 500 to supply power to each functional unit. The type of the charging interface 511 can be set according to the prevailing standard interface type (such as a type C interface), and no limitation is made here.

[0031] The intelligent display device 600 is installed with an application program that can respond to the writing / erasing information transmitted by the liquid crystal writing board and synchronously display the content on the liquid crystal writing board. In a preferred embodiment, the intelligent display device 600 can be optionally a computer, an interactive whiteboard, or an intelligent projector, without limitation here.

[0032] In this embodiment, when the user makes a writing action on the liquid crystal writing board, the writing trace is directly displayed on the liquid crystal writing film 200. At the same time, if the liquid crystal writing board is connected to the intelligent display device 600, the electromagnetic control unit 520 collects the writing trace through the electromagnetic antenna board 300 and transmits the writing trace information to the intelligent display device 600 through the data transmission unit 530. The intelligent display device 600 synchronously displays the content on the liquid crystal writing board according to the received writing trace information.

[0033] When the user makes an erasing action on the liquid crystal writing board, the electromagnetic control unit 520 collects the erasing information through the electromagnetic antenna board 300 and transmits the erasing information to the main control unit 540 through the data transmission unit 530. The main control unit 540 controls the liquid crystal driving unit 550 to drive the liquid crystal writing film 200 to erase the writing trace on the liquid crystal writing board. At the same time, if the liquid crystal writing board is connected to the intelligent display device 600, the data transmission unit 530 also transmits the erasing information to the intelligent display device 600, and the intelligent display device 600 synchronously erases the content on the liquid crystal writing board according to the received erasing information.

[0034] Compared with the existing ordinary electromagnetic writing board, this embodiment realizes the function of displaying the writing trace on the writing board by adding the liquid crystal writing film 200. When the user writes on this writing board, the writing board can display the user's writing content without always paying attention to the screen of the intelligent display device 600 (such as a computer).

[0035] Please refer to Figures 3 to 6, in an optional embodiment, the liquid crystal driving unit 550 includes a negative voltage pre-generation circuit 551, a negative voltage generation circuit 552, a bias voltage generation circuit 553, a horizontal liquid crystal driving circuit 554, and a vertical liquid crystal driving circuit 555. The controlled end of the negative voltage pre-generation circuit 551 is connected to the main control unit 540, the output end of the negative voltage pre-generation circuit 551 is connected to the input end of the negative voltage generation circuit 552, the output end of the negative voltage generation circuit 552 is connected to the output end of the bias voltage generation circuit 553, the first output end of the bias voltage generation circuit 553 is connected to the input end of the horizontal liquid crystal driving circuit 554, the second output end of the bias voltage generation circuit 553 is connected to the input end of the vertical liquid crystal driving circuit 555, the controlled end of the vertical liquid crystal driving circuit 555 is connected to the main control unit 540, the horizontal liquid crystal driving circuit 554 is configured to output a horizontal driving voltage to the liquid crystal writing film 200, and the vertical liquid crystal driving circuit 555 is configured to output a vertical driving voltage to the liquid crystal writing film 200.

[0036] In an optional embodiment, the liquid crystal writing film 200 includes an upper conductive layer (not shown in the figure), a liquid crystal layer (not shown in the figure), and a lower conductive layer (not shown in the figure) sequentially arranged from top to bottom. The upper conductive layer includes X horizontal conductive regions and Y vertical conductive regions, and each horizontal conductive region is perpendicular to each vertical conductive region. The lower conductive layer includes X horizontal conductive regions and Y vertical conductive regions corresponding to the upper conductive layer.

[0037] Optionally, as Figure 6 shown, the conductive layer is an ITO (Indium tin oxide) conductive terminal layer. The ITO conductive film refers to a high-tech material product obtained by sputtering a transparent indium tin oxide conductive thin film coating on materials such as a transparent organic film PET (polyethylene glycol terephthalate) using processing methods such as magnetron sputtering, evaporation, reactive ion plating, or chemical vapor deposition. The ITO conductive terminals are obtained by etching corresponding conductive film strips with the X-axis and Y-axis perpendicular to each other. For example, Figure 6 the X-axis 1 conductive strip, X-axis 2 conductive strip, X-axis 3 conductive strip... and the Y-axis 1 conductive strip, Y-axis 2 conductive strip, Y-axis 3 conductive strip... perpendicular to the X-axis in

[0038] Optionally, as Figure 5 shown, the negative voltage pre-generation circuit 551 includes a resistor R11, a resistor R12, a capacitor EC2, and N parallel-connected negative voltage control circuits 5511. The controlled terminals of each negative voltage control circuit 5511 are respectively connected to the main control unit 540. The feedback output terminals of each negative voltage control circuit 5511, the second terminal of the resistor R11, and the first terminal of the resistor R12 are connected to the feedback terminal of the negative voltage generation circuit 552. The output terminals of each negative voltage control circuit 5511, the second terminal of the resistor R12, and the first terminal of the capacitor EC2 are interconnected, and the connection node is the output terminal of the negative voltage pre-generation circuit 551; the first terminal of the resistor R11 and the second terminal of the capacitor EC2 are grounded, and N≥2.

[0039] The negative voltage control circuit 5511 includes a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a transistor Q1, a transistor Q2, and a transistor Q3. The gate of the transistor Q1 is connected to the first terminal of the resistor R1, and the connection node is the controlled terminal of the negative voltage control circuit 5511. The drain of the transistor Q1, the gate of the transistor Q2, and the second terminal of the resistor R2 are interconnected. The drain of the transistor Q2 is connected to the first terminal of the resistor R2. The second terminal of the resistor R3, the first terminal of the resistor R4, and the gate of the transistor Q3 are interconnected. The drain of the transistor Q3 is connected to the first terminal of the resistor R5, and the second terminal of the resistor R5 is the feedback output terminal of the negative voltage control circuit 5511; the source of the transistor Q3 is connected to the second terminal of the resistor R4, and the connection node is the output terminal of the negative voltage control circuit 5511. The source of the transistor Q2 and the first terminal of the resistor R2 are both connected to the power supply VCC, and the source of the transistor Q1 and the second terminal of the resistor R1 are both grounded.

[0040] Figure 5 In the circuit shown, another negative voltage control circuit 5511 includes a resistor R6, a resistor R7, a resistor R8, a resistor R9, a resistor R10, a transistor Q5, a transistor Q6, and a transistor Q7. The gate of the transistor Q5 is connected to the first terminal of the resistor R6, and the connection node is the controlled terminal of the negative voltage control circuit 5511. The drain of the transistor Q5, the second terminal of the resistor R8, and the gate of the transistor Q7 are interconnected. The drain of the transistor Q7 is connected to the first terminal of the resistor R10. The second terminal of the resistor R10, the first terminal of the resistor R9, and the gate of the transistor Q6 are interconnected. The drain of the transistor Q6 is connected to the first terminal of the resistor R7, and the second terminal of the resistor R7 is the feedback output terminal of the negative voltage control circuit 5511; the second terminal of the transistor Q6 is connected to the second terminal of the resistor R9, and the connection node is the output terminal of the negative voltage control circuit 5511. The drain of the transistor Q7 and the first terminal of the resistor R8 are both connected to the power supply VCC, and the source of the transistor Q5 and the second terminal of the resistor R6 are both grounded.

[0041] Here, the control levels output by the main control unit 540 (such as Figure 5 V-control-1 and V-control-N in

[0042] Figure 5 ) are loaded onto the multi-channel negative voltage control circuit 5511, and then multiple loop control impedances are obtained. This impedance is then input into the negative voltage control circuit 5511, and finally 1-channel, 2-channel, 3-channel... n-channel variable negative voltages are generated. After superposition and integration, an ideal liquid crystal driving voltage is obtained. The basic composition of the negative voltage control circuit 5511 consists of multiple field effect transistors, resistors, capacitors, etc., and can also be composed of transistors, resistors, and capacitors, or can be composed of a mixture of field effect transistors and transistors. Each negative voltage consists of a basic circuit, and several basic circuits are required for several negative voltages.

[0043] In an alternative embodiment, the data transmission unit 530 is wirelessly connected to the intelligent display device 600, and the data transmission unit 530 can wirelessly transmit writing or erasing signals to the intelligent display device 600. Preferably, please refer to Figure 3 The data transmission unit 530 includes a Bluetooth control circuit and a Bluetooth antenna. The input end of the Bluetooth control circuit is the input end of the data transmission unit 530. The first output end of the Bluetooth control circuit is the first output end of the data transmission unit 530. The second output end of the Bluetooth control circuit is connected to the Bluetooth antenna, and the Bluetooth antenna is the second output end of the data transmission unit 530.

[0044] It can be understood that in this embodiment, when the intelligent display device 600 includes a Bluetooth adapter circuit 630 corresponding to the Bluetooth control circuit, the writing or erasing information output by the electromagnetic control unit 520 can be transmitted to the intelligent display device 600 via Bluetooth. In an alternative embodiment, wireless connection between the data transmission unit 530 and the intelligent display device 600 can also be achieved by setting up a WIFI module (not shown in the figure) or an Internet of Things module (not shown in the figure), etc.

[0045] It is worth mentioning that, please refer to Figure 3 and Figure 4 To enrich the functions of the liquid crystal writing board, in an alternative embodiment, the Bluetooth control circuit includes a Bluetooth chip control circuit 531. The data transmission unit 530 further includes a display screen 532. The input end of the Bluetooth chip control circuit 531 is the input end of the Bluetooth control circuit. The first output end of the Bluetooth chip control circuit 531 is the first output end of the Bluetooth control circuit. The second output end of the Bluetooth chip control circuit 531 is the second output end of the Bluetooth control circuit. The third output end of the Bluetooth chip control circuit 531 is connected to the display screen 532. To further enrich the functions of the liquid crystal writing board, in an embodiment, the data transmission unit 530 further includes a memory 533 and a crystal oscillator 534, and the memory 533 and the crystal oscillator 534 are respectively connected to the Bluetooth chip control circuit 531.

[0046] Here, the electromagnetic control unit 520 and the Bluetooth chip control circuit 531 communicate through the USB protocol to transmit the data signal of the electromagnetic stylus 100 to the Bluetooth chip control circuit 531. The main control unit 540 mainly communicates through the serial port. The Bluetooth chip (not shown in the figure) transmits the erased data signal on the electromagnetic control unit 520 to the main control unit 540 through the serial port. The main control unit 540 finally completes the function of partial erasure of the handwriting on the liquid crystal writing film 200 through the negative voltage pre-generation circuit 551, the negative voltage generation circuit 552, the bias voltage generation circuit 553, the horizontal liquid crystal driving circuit 554, and the vertical liquid crystal driving circuit 555. The power supply unit 510 is used to supply power to the Bluetooth chip. The crystal oscillator 534 includes two frequencies of 32M and 32.768K and provides them to the Bluetooth chip control circuit 531. The memory 533 mainly stores the handwriting data in the memory 533 that can save data through the SPI bus. The display screen 532 mainly conducts data communication through the I2C serial port bus. The display screen 532 can display various information such as the working mode of the electromagnetic stylus 100, the working operation instructions, and the battery capacity, facilitating the customer to know the operations they perform. Through the Bluetooth antenna, the required data signal is sent to the Bluetooth adapter circuit 630 through the Bluetooth protocol. The Bluetooth adapter circuit 630 and the Bluetooth antenna communicate with the Bluetooth chip control circuit 531 of the host through the Bluetooth protocol. The Bluetooth chip control module (not shown in the figure) inside the Bluetooth adapter circuit 630 is connected to the teaching all-in-one machine or the computer through the standard USB-A interface, processes and converts the wireless signal obtained by the antenna, and then inputs it to the intelligent display device 600 (such as a computer or a teaching all-in-one machine) through the USB port.

[0047] Please refer to Figure 3 , in an optional embodiment, the electronic control module 500 further includes a temperature sensor circuit 560, and the output end of the temperature sensor circuit 560 is connected to the second input end of the main control unit 540. Here, the temperature sensor circuit 560 can obtain the analog voltage values at different temperatures and then send the data to the main control unit 540 for the automatic control of the liquid crystal driving voltage.

[0048] The present invention also proposes a liquid crystal writing board system, including the liquid crystal writing board as described above and an electromagnetic stylus 100 adapted to the liquid crystal writing board. A writing / erasing mode selection button is provided on the electromagnetic stylus 100. Further, the liquid crystal writing board system further includes an intelligent display device 600 adapted to the liquid crystal writing board, and an electromagnetic stylus 100 / mouse mode selection button is further provided on the electromagnetic stylus 100.

[0049] Next, in combination with Figures 1 to 6 , the working principles of this liquid crystal writing board and the liquid crystal writing board system will be described in detail:

[0050] When the electromagnetic stylus 100 writes or erases on the locally erasable liquid crystal film, the electromagnetic stylus 100 will generate magnetic signals of different frequencies on the electromagnetic antenna board 300. The electromagnetic stylus 100 itself has no power source, but when the electromagnetic stylus 100 is placed on the electromagnetic antenna board 300, the inductive coil inside the electromagnetic stylus 100 will obtain an induced voltage and current to generate a signal. The position data of this signal, as well as data such as the tilt angle and pressure value of the electromagnetic stylus 100, will be input into the electromagnetic control unit 520. After signal recognition and conversion by the electromagnetic control unit 520, the coordinate data signal of the writing or erasing trace will be transmitted to the Bluetooth control circuit through the USB bus. The Bluetooth control circuit will split the obtained data signal into two paths. The writing trace data and the erasing trace data are wirelessly transmitted through the Bluetooth protocol. The erasing trace data is additionally transmitted to the main control unit 540 through the serial port signal. After receiving the data signal, the main control unit 540 will transmit the data to the liquid crystal driving unit 550. Under the combined drive of the negative voltage pre-generation circuit 551, the negative voltage generation circuit 552, and the bias voltage generation circuit 553 for the horizontal liquid crystal driving circuit 554 and the vertical liquid crystal driving circuit 555, the function of locally erasing the liquid crystal writing film 200 is completed. Additionally, on the side of the intelligent display device 600 (such as an interactive whiteboard or a computer), there is a Bluetooth adapter circuit 630. The Bluetooth adapter circuit 630 is internally provided with a Bluetooth chip module (not shown in the figure). The USB Dongle in this Bluetooth adapter circuit 630 has been paired with the Bluetooth control circuit on the liquid crystal writing board before. Therefore, the data wirelessly transmitted from the liquid crystal writing board is input into the corresponding application software through the USB Dongle in the Bluetooth adapter circuit 630 and then through the USB port of the interactive whiteboard or the computer. The application software can display the writing and erasing actions of the trace on the interactive whiteboard or the computer. Additionally, the USB dongle defines the control device protocol of the Windows HID standard. Through mode switching settings, our electromagnetic stylus 100 can work in two modes: the writing board mode and the mouse mode, facilitating users to wirelessly operate the interactive whiteboard or the computer, including opening and closing programs, writing and locally erasing in the application software, etc.

[0051] This solution obtains the writing and erasing data signals of the electromagnetic stylus 100 on the electromagnetic antenna board 300, and then the Bluetooth control circuit transmits the data in two paths. One path wirelessly transmits the data signal to the USB Dongle in the Bluetooth adapter circuit 630 through the 2.4G Bluetooth protocol, and the USB Dongle transmits the data signal to the teaching all-in-one machine or computer through USB for display, storage and sharing. The second path of the erasing data signal is input to the main control unit 540 through the serial port, and then the main control unit 540 controls the multi-channel negative voltage control 5511 circuit to superimpose and integrate to output an appropriate negative voltage. Finally, the data drives the corresponding positions of the liquid crystal writing film 200 through the horizontal liquid crystal driving circuit 554 and the vertical liquid crystal driving circuit 555, so as to achieve the ideal local erasing effect of the liquid crystal writing board. This solution defines the communication protocols of the electromagnetic antenna board 300, the Bluetooth chip and the main control unit 540, can complete the writing and local erasing of the writing board, can complete the Bluetooth wireless transmission to the teaching all-in-one machine or computer for handwriting display, local erasing and mouse functions.

[0052] It should be noted that the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions conflicts with each other or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0053] The above are only partial or preferred embodiments of the present invention. Whether in terms of text or drawings, the scope of protection of the present invention cannot be limited thereby. Any equivalent structural transformation made by using the content of the specification and drawings of the present invention under the overall concept of the present invention, or any direct / indirect application in other related technical fields is included in the scope of protection of the present invention.

Claims

1. A liquid crystal writing board, characterized in that, It includes an electronic control module, a liquid crystal writing film, an electromagnetic antenna board, and a writing substrate arranged in sequence from top to bottom. The electronic control module includes a power supply unit, a main control unit, an electromagnetic control unit, a liquid crystal driving unit, and a data transmission unit; The power supply terminals of the electromagnetic control unit, the data transmission unit, the main control unit, and the liquid crystal driving unit are all connected to the power supply unit. The data acquisition terminal of the electromagnetic control unit is connected to the electromagnetic antenna board. The output terminal of the electromagnetic control unit is connected to the input terminal of the data transmission unit. The first output terminal of the data transmission unit is connected to the first input terminal of the main control unit. The control terminal of the main control unit is connected to the controlled terminal of the liquid crystal driving unit. The output terminal of the liquid crystal driving unit is connected to the liquid crystal writing film; Among them, the data transmission unit further includes a second output terminal for connecting to an intelligent display device. When a user performs a writing or erasing action on the liquid crystal writing board, the data transmission unit transmits a signal corresponding to the writing or erasing action to the intelligent display device, so that the intelligent display device responds to the writing or erasing action.

2. The liquid crystal writing board according to claim 1, characterized in that, The liquid crystal driving unit includes a negative voltage pre-generation circuit, a negative voltage generation circuit, a bias voltage generation circuit, a horizontal liquid crystal driving circuit, and a vertical liquid crystal driving circuit. The controlled terminal of the negative voltage pre-generation circuit is connected to the main control unit. The output terminal of the negative voltage pre-generation circuit is connected to the input terminal of the negative voltage generation circuit. The output terminal of the negative voltage generation circuit is connected to the output terminal of the bias voltage generation circuit. The first output terminal of the bias voltage generation circuit is connected to the input terminal of the horizontal liquid crystal driving circuit. The second output terminal of the bias voltage generation circuit is connected to the input terminal of the vertical liquid crystal driving circuit. The controlled terminal of the vertical liquid crystal driving circuit is connected to the main control unit. The horizontal liquid crystal driving circuit is used to output a horizontal driving voltage to the liquid crystal writing film, and the vertical liquid crystal driving circuit is used to output a vertical driving voltage to the liquid crystal writing film.

3. The liquid crystal writing board according to claim 2, characterized in that, The negative voltage pre-generation circuit includes a resistor R11, a resistor R12, a capacitor EC2, and N parallel-connected negative voltage control circuits. The controlled terminals of each negative voltage control circuit are respectively connected to the main control unit. The feedback output terminals of each negative voltage control circuit, the second terminal of the resistor R11, and the first terminal of the resistor R12 are connected to the feedback terminal of the negative voltage generation circuit. The output terminals of each negative voltage control circuit, the second terminal of the resistor R12, and the first terminal of the capacitor EC2 are interconnected, and the connection node is the output terminal of the negative voltage pre-generation circuit; the first terminal of the resistor R11 and the second terminal of the capacitor EC2 are grounded, and N≥2.

4. The liquid crystal writing board according to claim 3, wherein The negative voltage control circuit includes resistor R1, resistor R2, resistor R3, resistor R4, resistor R5, transistor Q1, transistor Q2, and transistor Q3. The gate of transistor Q1 is connected to the first end of resistor R1, and the connection node is the controlled end of the negative voltage control circuit. The drain of transistor Q1, the gate of transistor Q2, and the second end of resistor R2 are interconnected. The drain of transistor Q2 is connected to the first end of resistor R2. The second end of resistor R3, the first end of resistor R4, and the gate of transistor Q3 are interconnected. The drain of transistor Q3 is connected to the first end of resistor R5, and the second end of resistor R5 is the feedback output end of the negative voltage control circuit; The source of transistor Q3 is connected to the second end of resistor R4, and the connection node is the output end of the negative voltage control circuit. The source of transistor Q2 and the first end of resistor R2 are both connected to power supply VCC. The source of transistor Q1 and the second end of resistor R1 are both grounded.

5. The liquid crystal writing board according to claim 1, wherein The liquid crystal writing film includes an upper conductive layer, a liquid crystal layer, and a lower conductive layer arranged in sequence from top to bottom. The upper conductive layer includes X horizontal conductive regions and Y vertical conductive regions, and each of the horizontal conductive regions is perpendicular to each of the vertical conductive regions. The lower conductive layer includes X horizontal conductive regions and Y vertical conductive regions corresponding to the upper conductive layer.

6. The liquid crystal writing board according to claim 1, wherein The data transmission unit includes a Bluetooth control circuit and a Bluetooth antenna. The input end of the Bluetooth control circuit is the input end of the data transmission unit. The first output end of the Bluetooth control circuit is the first output end of the data transmission unit. The second output end of the Bluetooth control circuit is connected to the Bluetooth antenna, and the Bluetooth antenna is the second output end of the data transmission unit.

7. The liquid crystal writing board according to claim 6, wherein, The Bluetooth control circuit includes a Bluetooth chip control circuit. The data transmission unit further includes a display screen. The input end of the Bluetooth chip control circuit is the input end of the Bluetooth control circuit. The first output end of the Bluetooth chip control circuit is the first output end of the Bluetooth control circuit. The second output end of the Bluetooth chip control circuit is the second output end of the Bluetooth control circuit. The third output end of the Bluetooth chip control circuit is connected to the display screen.

8. The liquid crystal writing board according to claim 1, wherein The electronic control module further includes a temperature sensor circuit, and the output end of the temperature sensor circuit is connected to the second input end of the main control unit.

9. A liquid crystal writing tablet system, characterized in that, It includes the liquid crystal writing board according to any one of claims 1-8 and a writing pen adapted to the liquid crystal writing board, and a writing / erasing mode selection button is provided on the writing pen.

10. The liquid crystal writing board system according to claim 9, wherein, The liquid crystal writing board system further includes an intelligent display device adapted to the liquid crystal writing board, and a writing pen / mouse mode selection button is further provided on the writing pen.

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