CN107632735A - A kind of handwriting device, liquid crystal handwriting board device and method for deleting - Google Patents

Abstract

The invention discloses a kind of handwriting device, liquid crystal handwriting board device and method for deleting.The handwriting device includes power supply, switch, power transmission circuit, power transmission drive circuit and power transmission coil；First control terminal of the power transmission circuit electrically connects with the switch, transmits the voltage of the output end of the power supply to the power input of the power transmission drive circuit for the control according to the switch；The output end of the power transmission drive circuit electrically connects with the power transmission coil, for after the power-up, to the power transmission electrical coil output signal；The power transmission coil is used for when being applied in corresponding electric signal, is acted on neighbouring electricity reception coil, the electricity reception coil is produced alternating current.So, power supply, switch etc. are arranged in handwriting device, the handwriting device can reach the purpose for removing liquid crystal handwriting board device display content by way of wireless power transmission to liquid crystal handwriting board device power transmission；Further, liquid crystal handwriting board device is salable, meets waterproof requirement, and application places are more extensive.

Description

Handwriting device, liquid crystal tablet device and erasing method

technical field

The embodiments of the present invention relate to the field of handwriting tablets, in particular to a handwriting device, a liquid crystal tablet device and an erasing method.

Background technique

The erasing principle of the liquid crystal writing board device is to generate an electric field at both ends of the liquid crystal, so that the liquid crystals arranged disorderly by external force can restore the original orderly arrangement, so as to achieve the purpose of clearing the content on the liquid crystal writing board device.

Usually, a battery, a power management circuit and an erase switch are arranged on the liquid crystal tablet device. After the erasing switch is pressed, the power management circuit processes the battery voltage and outputs the voltage to the film electrodes of the liquid crystal tablet device, and an electric field is generated between the film electrodes to erase the content displayed on the liquid crystal tablet device. The erasing switch is set on the handwriting board, and the user may accidentally press the switch during the writing process, causing the written content to be erased by mistake. At the same time, due to the influence of the erase switch, battery, battery holder, battery cover and other factors, it is extremely difficult for the liquid crystal tablet device to meet the requirements of dustproof and waterproof, and the applicable places of product design are relatively limited.

Contents of the invention

The invention provides a handwriting device, a liquid crystal writing board device and an erasing method, which can improve the flexibility of the liquid crystal writing board, and at the same time, realize the sealing of the liquid crystal writing board device, so that the liquid crystal writing board device can be dustproof and waterproof, and the application place is more convenient. wide.

The embodiment of the present invention proposes to set the power supply, switch, power transmission circuit, power transmission drive circuit and power transmission coil in the handwriting device, and to set the power receiving coil and power receiving drive circuit in the liquid crystal tablet device, through wireless power transmission , the handwriting device sends power to the liquid crystal tablet device to realize the purpose of clearing the display content of the liquid crystal tablet device; this solution can avoid the wrong erasure of the written content on the tablet by adopting the method of separating the erase switch from the tablet, and improve the quality of handwriting. The flexibility of the board; at the same time, the liquid crystal handwriting board device is sealed to meet the requirements of dustproof and waterproof, and the product design can be used in more places.

In a first aspect, an embodiment of the present invention provides a handwriting device, which includes: a power supply, a switch, a power transmission circuit, a power transmission drive circuit, and a power transmission coil;

The input end of the power transmission circuit is electrically connected to the output end of the power supply, the output end of the power transmission circuit is electrically connected to the power input end of the power transmission drive circuit, the first control end of the power transmission circuit is connected to the The switch is electrically connected, and is used to transmit the voltage of the output end of the power supply to the power input end of the power transmission drive circuit according to the control of the switch;

The output terminal of the power transmission drive circuit is electrically connected to the power transmission coil, and is used to output an electrical signal to the power transmission coil after power-on;

The power transmitting coil is used for interacting with a nearby power receiving coil when a corresponding electric signal is applied to make the power receiving coil generate alternating current. Further, the handwriting device also includes: a power conditioning circuit and a control unit;

The input end of the power conditioning circuit is electrically connected to the output end of the power transmission circuit, the output end of the power conditioning circuit is electrically connected to the control unit, and is used to switch the power transmission circuit to the The voltage output from the output terminal of the power transmission circuit is converted to supply power to the control unit;

The control unit is electrically connected to the second control terminal of the power transmission circuit, and is used for controlling the conduction of the power transmission circuit when it detects that the switch is turned on after power-on operation, and sends the power transmission circuit to the The power transmission drive circuit outputs a control signal to control the frequency of the electric signal output by the power transmission drive circuit.

Further, the power transmission circuit in the handwriting device includes: a first triode, a second triode, a first diode, a second diode, a first resistor, a second resistor, a third resistor and the fourth resistor;

The first pole of the first triode is electrically connected to the input end of the power transmission circuit, the second pole of the first triode is electrically connected to the output end of the power transmission circuit, and the first The base of the triode is electrically connected to the second pole of the second triode through the first resistor;

One end of the second resistor is electrically connected to the first pole of the first triode, and the other end of the second resistor is electrically connected to the base of the first triode;

The first pole of the second triode is grounded, and the base of the second triode is electrically connected to the output terminal of the control unit through the third resistor;

One end of the fourth resistor is connected to one end of the third resistor connected to the control unit; the other end of the fourth resistor is grounded;

The first pole of the first diode is electrically connected to the second pole of the second triode, and the second pole of the first diode is electrically connected to the first control terminal of the power transmission circuit ;

The first pole of the second diode is electrically connected to the control unit, and the second pole of the second diode is electrically connected to the first pole of the first diode.

Further, the power transmission drive circuit in the handwriting device adopts LT4531.

Further, the frequency of the output signal of the power transmission driving circuit in the handwriting device is 0.25 Hz.

Further, the switch in the handwriting device is a key switch.

In a second aspect, an embodiment of the present invention provides a liquid crystal tablet device, which includes a power receiving coil and a power receiving drive circuit;

The power receiving coil is used to interact with the power transmitting coil to generate alternating current;

The input end of the power receiving drive circuit is electrically connected to the power receiving coil, and the output end of the power receiving drive circuit is electrically connected to the thin film electrode on the liquid crystal tablet device, which is used to transfer the alternating current on the power receiving coil to It is converted into direct current and output to the thin-film electrode to erase the content displayed by the liquid crystal tablet device.

Further, the liquid crystal tablet device also includes a first capacitor;

The first capacitor is connected in parallel to both ends of the receiving coil;

The power receiving drive circuit includes a bridge rectifier circuit and a second capacitor, the two input terminals of the bridge rectifier circuit are respectively electrically connected to the two ends of the power receiving coil, and the two output terminals of the bridge rectifier circuit The terminals are respectively electrically connected to the two thin-film electrodes;

The second capacitor is connected in parallel with two output terminals of the bridge rectifier circuit.

Further, the liquid crystal tablet device also includes a Zener diode and a third triode;

The first pole and the second pole of the third triode are respectively electrically connected to the two output ends of the bridge rectifier circuit;

The first pole of the Zener diode is electrically connected to the base of the third transistor, and the second pole of the Zener diode is electrically connected to the second pole of the third transistor.

In a third aspect, an embodiment of the present invention provides an erasing method for a liquid crystal tablet device, the erasing method is suitable for a handwriting device and a liquid crystal tablet device, including:

The handwriting device transmits power to the liquid crystal tablet device through wireless power transmission;

The liquid crystal tablet device is driven to erase the displayed content of the liquid crystal tablet device according to the electric energy transmitted by the handwriting device.

Further, the handwriting device includes a power supply, a switch, a power transmission circuit, a power transmission drive circuit, and a power transmission coil; the input end of the power transmission circuit is electrically connected to the output end of the power supply, and the output of the power transmission circuit end is electrically connected to the power input end of the power transmission drive circuit, the first control terminal of the power transmission circuit is electrically connected to the switch, and the output end of the power transmission drive circuit is electrically connected to the power transmission coil;

The liquid crystal tablet device includes a power receiving coil and a power receiving drive circuit; the input end of the power receiving drive circuit is electrically connected to the power receiving coil, and the output end of the power receiving drive circuit is connected to the film electrode on the liquid crystal tablet device electrical connection;

The erasing method also includes:

When the switch is turned on, the power transmission circuit is turned on, the power transmission drive circuit is powered on, and the power transmission drive circuit outputs an electrical signal to the power transmission coil;

The power transmission coil interacts with the power receiving coil, and the power receiving coil generates alternating current; the power receiving drive circuit converts the alternating current into direct current and outputs it to the thin film electrode, and the content displayed on the liquid crystal tablet device erase.

Further, the handwriting device also includes a power conditioning circuit and a control unit;

The input end of the power conditioning circuit is electrically connected to the output end of the power transmission circuit, and the output end of the power conditioning circuit is electrically connected to the control unit;

The control unit is electrically connected to the second control terminal of the power transmission circuit;

The erasing method also includes:

When the power transmission circuit is turned on, the control unit is powered on, the control unit detects whether the switch is turned on, and when the switch is turned on, sends a first control signal to the power transmission circuit to control The power transmission circuit is continuously turned on.

Further, the erasing method further includes: after the control unit is powered on, monitoring the duration of the conduction of the switch, and if the duration of the conduction of the switch is longer than a preset duration, the control unit stops sending the first a control signal; if the conduction time of the switch is less than the preset duration, the control unit continues to send the first control signal to the power transmission circuit until the conduction duration of the power transmission circuit is greater than or equal to the When the time is preset, the control unit sends a second control signal to the power transmission circuit to control the power transmission circuit to turn off;

Wherein, the preset duration is greater than or equal to the minimum duration for which the liquid crystal tablet device needs to be powered on to erase the displayed content.

In the technical solution provided by the embodiment of the present invention, the power supply, switch, power transmission circuit, power transmission drive circuit and power transmission coil are arranged in the handwriting device, and the power receiving coil and the power receiving drive circuit are arranged in the liquid crystal tablet device. Wireless power transmission mode, the handwriting device sends power to the LCD tablet device to realize the purpose of clearing the display content of the LCD tablet device; this solution can avoid the wrong erasure of the written content on the tablet by adopting the method of separating the erase switch from the tablet In addition to improving the flexibility of the tablet; at the same time, it solves the problem that the liquid crystal tablet device is extremely difficult to be dustproof and waterproof, and the applicable place of the product design is limited, and the liquid crystal tablet device is sealed to meet the requirements of dustproof and waterproof Product design can be used in more places.

Description of drawings

FIG. 1 is a block diagram of a circuit structure of a handwriting device provided by Embodiment 1 of the present invention.

FIG. 2 is a block diagram of a circuit structure of a liquid crystal tablet device provided by Embodiment 1 of the present invention.

FIG. 3 is a block diagram of the circuit structure of another handwriting device provided in Embodiment 1 of the present invention.

FIG. 4 is a circuit diagram of a handwriting device provided in Embodiment 2 of the present invention.

Fig. 5 is a circuit diagram of a liquid crystal tablet device provided by Embodiment 3 of the present invention.

FIG. 6 is a circuit diagram of another liquid crystal tablet device provided by Embodiment 3 of the present invention.

FIG. 7 is a flow chart of the erasing method of the liquid crystal tablet device provided by the fourth embodiment of the present invention.

detailed description

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, only some structures related to the present invention are shown in the drawings but not all structures.

Embodiment one

FIG. 1 is a block diagram of a circuit structure of a handwriting device provided by Embodiment 1 of the present invention. As shown in Figure 1, the handwriting device includes a power supply 101, a switch 102, a power transmission circuit 103, a power transmission drive circuit 104 and a power transmission coil 105;

The input terminal Vin of the power transmission circuit 103 is electrically connected to the output terminal of the power supply 101, the output terminal Vout of the power transmission circuit 103 is electrically connected to the power input terminal of the power transmission drive circuit 104, and the first control terminal ctrl1 of the power transmission circuit 103 is connected to the switch 102 is electrically connected, and is used to transmit the voltage of the output end of the power supply 101 to the power input end of the power transmission drive circuit 104 according to the control of the switch 102;

The output terminal Vout of the power transmission drive circuit 104 is electrically connected to the power transmission coil 105, and is used to output an electrical signal to the power transmission coil 105 after power-on;

The power transmitting coil 105 is used for interacting with a nearby power receiving coil when a corresponding electric signal is applied to make the power receiving coil generate alternating current.

FIG. 2 is a block diagram of a circuit structure of a liquid crystal tablet device provided in Embodiment 1 of the present invention. As shown in FIG. 2 , the liquid crystal tablet device includes a power receiving coil 201 and a power receiving drive circuit 202;

The power receiving coil 201 is used to interact with the power transmitting coil 105 to generate alternating current; for example, interact with the power transmitting coil on the handwriting device shown in FIG. 1 to generate alternating current.

The input end of the power receiving drive circuit 202 is electrically connected with the power receiving coil 201, and the output end of the power receiving drive circuit 202 is electrically connected with the film electrode on the liquid crystal tablet device, for converting the alternating current on the power receiving coil 201 into a direct current and Output to the thin film electrode to erase the content displayed by the liquid crystal tablet device.

The working process of the handwriting device shown in FIG. 1 and the liquid crystal tablet device shown in FIG. 2 will be described below as examples. The switch 102 may be a key switch, and the handwriting device may be a stylus. Exemplarily, put the handwriting device close to the liquid crystal tablet device, press the switch 102 on the handwriting device, the switch 102 is closed and turned on, and the power transmission circuit 103 is controlled to be turned on. After the power transmission circuit 103 is turned on, the voltage at the output end of the power supply 101 It is transmitted to the power input terminal Vin of the power transmission drive circuit 104, and the power transmission drive circuit 104 is powered on. After the power transmission drive circuit 104 is powered on, it outputs an electrical signal to the power transmission coil 105. After the electrical signal is loaded on the power transmission coil 105, it is sent The electric coil 105 can interact with the power receiving coil 201 on the nearby liquid crystal tablet device, and the power receiving coil 201 generates alternating current. The power receiving drive circuit 202 converts the AC power on the power receiving coil 201 into a DC power and outputs it to the thin film electrode, and erases the content displayed on the liquid crystal tablet device.

In the technical solution provided by the embodiment of the present invention, the power supply, switch, power transmission circuit, power transmission drive circuit and power transmission coil are arranged in the handwriting device, and the conduction of the power transmission circuit is controlled by the switch, and then the power transmission circuit and the power transmission drive Under the joint action of the circuit, an electrical signal is output to the power transmitting coil, and the power transmitting coil can interact with the power receiving coil on the liquid crystal tablet device to generate alternating current, and the power receiving drive circuit converts the alternating current on the power receiving coil into direct current and outputs it to the film The electrodes realize the erasing of the display content of the liquid crystal tablet device. Since the switch and the power supply are both arranged on the handwriting device, the handwriting device transmits electric energy to the liquid crystal tablet device through wireless power transmission, thereby realizing erasing of the displayed content on the liquid crystal tablet device. This technical solution adopts the method of separating the erasing switch from the handwriting board, which can avoid the accidental erasure of the written content on the handwriting board and improve the flexibility of the handwriting board; at the same time, the liquid crystal writing board device is easy to seal, and the liquid crystal writing board device is easy to meet waterproof requirements requirements, improve the application scope of the liquid crystal tablet device, and the application places are wider.

Further, as shown in FIG. 3 , FIG. 3 is a circuit block diagram of another handwriting device provided in Embodiment 1 of the present invention. On the basis of the circuit shown in FIG. 1 , the handwriting device also includes a power conditioning circuit 106 and a control unit 107 ;

The input terminal of the power conditioning circuit 106 is electrically connected to the output terminal Vout of the power transmission circuit 103, and the output terminal of the power conditioning circuit 106 is electrically connected to the control unit 107, which is used to output the power transmission circuit 103 when the power transmission circuit 103 is turned on. The voltage output from the terminal Vout is converted to supply power to the control unit 107;

The control unit 107 is electrically connected to the second control terminal ctrl2 of the power transmission circuit 103, and is used to control the power transmission circuit 103 to conduct when the switch 102 is detected to be turned on after power-on operation, and to send power to the power transmission drive circuit 104 The control signal is output to control the frequency of the electric signal output by the power transmission drive circuit 104 .

In the technical solution provided by the embodiment of the present invention, the switch 102 can be used to control the conduction of the power transmission circuit 103 to provide an electrical signal to the power transmission coil 105, or the control unit 107 can control the conduction of the power transmission circuit 103, and then to the power transmission Coil 105 provides an electrical signal. Specifically, the switch 102 is turned on when it is pressed; it is turned off when it is not pressed. When the switch 102 is turned on, the power transmission circuit 103 is turned on, the power transmission drive circuit 104 and the control unit 107 are powered on, and the control unit 107 detects whether the switch 102 is turned on. The first control signal is sent to control the power transmission circuit 103 to be continuously turned on. At this time, if the switch 102 is turned off, the control unit 107 may also continuously control the power transmission circuit 103 to be continuously turned on. When the power transmission circuit 103 is turned on for longer than a preset time, the control unit 107 may send a second control signal to the power transmission circuit 103 to control the power transmission circuit 103 to be turned off.

According to the technical solution provided by the implementation of the present invention, the switch 102 can be a key switch. When the user presses the switch 102 once, the control unit 107 can control the power transmission circuit 103 to continue conducting, and then send an electrical signal for a sufficient time to the power transmission coil 105 . The user can also press the switch 102 for a long time, and the switch 102 directly controls the on and off of the power transmission circuit 103 . Specifically, after the control unit 107 is powered on, it detects whether the switch 102 is conducting, and when the detection switch 102 is conducting, then monitors whether the duration of the switch 102 conducting reaches the preset duration, if the duration of the switch 102 conducting is greater than the preset duration, Then stop sending the first control signal to the power transmission circuit 103 , and in a subsequent period of time, when the switch 102 is turned off, the power transmission circuit 103 is also turned off.

Wherein, the power conditioning circuit 106 may be a voltage regulator. For example, it may be a voltage dividing resistor for adjusting the voltage output to the control unit.

Wherein, the control unit 107 may be a single-chip micro-control system.

Embodiment two

Fig. 4 is the circuit diagram of a kind of handwriting device that the embodiment 2 of the present invention provides, as shown in Fig. 4, on the basis of above-mentioned embodiment, the power transmission circuit 103 in the handwriting device comprises: the first triode Q1, the second Transistor Q2, first diode D1, second diode D2, first resistor R1, second resistor R2, third resistor R3 and fourth resistor R4;

The first pole 111 of the first triode Q1 is electrically connected to the input terminal Vin of the power transmission circuit 103, the second pole 112 of the first triode Q1 is electrically connected to the output terminal Vout of the power transmission circuit 103, and the first triode The base 113 of the transistor Q1 is electrically connected to the second pole 122 of the second triode Q2 through the first resistor R1;

One end of the second resistor R2 is electrically connected to the first pole 111 of the first transistor Q1, and the other end of the second resistor R2 is electrically connected to the base 113 of the first transistor Q1;

The first pole 121 of the second triode Q2 is grounded, and the base 123 of the second triode Q2 is electrically connected to the output terminal of the control unit 107 through the third resistor R3;

One end of the fourth resistor R4 is connected to one end of the third resistor R3 connected to the control unit 107; the other end of the fourth resistor R4 is grounded;

The first pole 131 of the first diode D1 is electrically connected to the second pole 123 of the second triode Q2, and the second pole 132 of the first diode D1 is electrically connected to the first control terminal ctrl1 of the power transmission circuit 103 ;

The first pole 141 of the second diode D2 is electrically connected to the control unit 107 , and the second pole 142 of the second diode D2 is electrically connected to the first pole 131 of the first diode D1 .

Wherein, the first resistor R1 is used to limit the current of the first transistor Q1, the third resistor R3 is used to limit the current of the second transistor Q2, and the optional resistance ranges of the first resistor R1 and the third resistor R3 are both 1KΩ-5.1KΩ, the preferred resistance value is 2.2KΩ.

Wherein, the selectable resistance value ranges of the second resistor R2 and the fourth resistor R4 are both 10KΩ-100KΩ, and the preferred resistance value is 10KΩ.

Wherein, the first diode D1 and the second diode D2 are used for setting the signal flow rate, and specific parameter values are not limited.

Wherein, the first triode Q1 and the second triode Q2 are used to control the on-off of the circuit, and the specific parameter values are not limited.

The power transmission driving circuit 204 can adopt LT4531.

The frequency of the output signal of the power transmission drive circuit 204 is 0.25 Hz.

Exemplarily, the switch 102 in the handwriting device may be a key switch.

The working process of the handwriting device provided by the embodiment of the present invention will be described below in conjunction with the circuit shown in FIG. 4 , taking the first transistor Q1 as an NPN transistor and the second transistor Q2 as a PNP transistor as an example. When the switch S1 is not pressed, the switch S1 is turned off, and due to the pull-down effect of the fourth resistor R4, the base of the second transistor Q2 is at a low level, and the second transistor Q2 is turned off. Due to the pull-up effect of the second resistor R2, the base of the first transistor Q1 is at a high level, and the first transistor Q1 is turned off. The power transmission drive circuit 104 has no power supply and does not output electrical signals. When the switch S1 is pressed, the switch S1 is turned on, the base of the first triode Q1 is at a low level, the first triode Q1 is turned on, and the voltage at the output terminal of the power supply 101 is provided to the power transmission drive circuit 104, and the power transmission drive The circuit 104 is powered on and outputs an electrical signal; the voltage at the output end of the power supply 101 is converted by the power conditioning circuit 106 and then output to the control unit 107, and the control unit 107 is powered on, and the control unit 107 can output a control signal to the power transmission drive circuit 104 to control the power transmission The electric drive circuit 104 outputs the frequency of the electric signal so that the frequency of the electric signal output by the power transmission drive circuit 104 meets the requirements, and the power transmission coil 105 and the power receiving coil 201 can act, and the power receiving coil 201 generates alternating current. After the control unit 107 is powered on, it can output a high-level signal to the common connection terminal of the third resistor R3 and the fourth resistor R4, the base of the second transistor Q2 is at a high level, the second transistor Q2 is turned on, and the second transistor Q2 is turned on. The base of the triode Q1 is at a low level, which controls the first triode Q1 to be continuously turned on. At this time, even if the switch S1 is turned off, the control unit 107 can control the first triode Q1 to be continuously turned on. The control unit 107 detects that the switch S1 is turned on for a preset time, for example, the switch S1 is turned on for 2s. When the switch S1 is turned on for less than the preset time, the control unit 107 continues to output a high level signal to the first The common connection end of the three resistors R3 and the fourth resistor R4 is turned on by the second transistor Q2, thereby controlling the continuous conduction of the first transistor Q1. When the conduction period of the first transistor Q1 is longer than the preset duration, the control unit 107 outputs a low level signal to the common connection terminal of the third resistor R3 and the fourth resistor R4, and the second transistor Q2 is turned off. Due to the pull-up effect of the second resistor R2, the base of the first transistor Q1 is at a high level, and the first transistor Q1 is turned off. If the control unit 107 detects that the switch S1 is turned on for a preset duration, the control unit 107 stops outputting a high-level signal to the common connection terminal of the third resistor R3 and the fourth resistor R4, or outputs a low-level signal to the third resistor R3. The common connection end of the resistor R3 and the fourth resistor R4, the second transistor Q2 is turned off. Since the switch S1 is still turned on, the base of the first transistor Q1 is at a low level, and the first transistor Q1 is continuously turned on. If the switch S1 is turned off at a subsequent time, due to the pull-up effect of the second resistor R2, the base of the first transistor Q1 is at a high level, and the first transistor Q1 is turned off, that is, when the switch S1 is turned off, The first triode Q1 is turned off, and the entire power transmission circuit 103 is turned off.

It should be noted that, since the erasing of the displayed content on the liquid crystal tablet device requires the duration of output voltage to the liquid crystal film electrode to meet certain requirements, the duration of the conduction of the power transmission circuit needs to meet certain requirements, and then provide power to the power transmission coil. The duration of the signal meets certain requirements. Therefore, the preset duration needs to be greater than or equal to the minimum duration that the liquid crystal tablet device needs to be powered on to erase the displayed content.

In the technical solution provided by this embodiment, the power supply, the switch, the power transmission circuit, the power transmission drive circuit and the power transmission coil are arranged in the handwriting device, and the switch control circuit is turned on, so that the power transmission circuit and the power transmission drive circuit can be connected together. Under the action, power is supplied to the external circuit, that is, the circuit in the liquid crystal tablet device via the power transmission coil.

Embodiment three

Fig. 5 is a circuit diagram of a liquid crystal tablet device provided in Embodiment 3 of the present invention. As shown in Fig. 5, on the basis of Embodiment 1, the liquid crystal tablet device further includes a first capacitor C1;

The first capacitor C1 is connected in parallel with both ends of the receiving coil 201;

The power receiving drive circuit 202 includes a bridge rectifier circuit BD and a second capacitor C2, the two input terminals of the bridge rectifier circuit BD are respectively electrically connected to the two ends of the power receiving coil 201, and the two output terminals of the bridge rectifier circuit BD are respectively Electrically connected to two thin-film electrodes;

The second capacitor C2 is connected in parallel with the two output terminals of the bridge rectifier circuit BD.

Wherein, the first capacitor C1 is used for removing signal interference after the receiving coil 201 receives electric energy.

Among them, the bridge rectifier circuit BD includes four diodes, which are respectively the third diode D3, the fourth diode D4, the fifth diode D5 and the sixth diode D6. , the four diodes preferably use Schottky diodes.

Wherein, the second capacitor C2 is used for rectification and filtering, preferably a filter capacitor of 100V/47μf.

Further, as shown in FIG. 6, FIG. 6 is a circuit diagram of another liquid crystal tablet device provided in Embodiment 3 of the present invention. The liquid crystal tablet device also includes a Zener diode ZD and a third transistor Q3;

The first pole 211 and the second pole 212 of the third triode Q3 are respectively electrically connected to the two output ends of the bridge rectifier circuit;

The first pole 221 of the Zener diode ZD is electrically connected to the base 213 of the third transistor Q3, and the second pole 222 of the Zener diode ZD is electrically connected to the second pole 212 of the third transistor Q3.

Wherein, the Zener diode ZD is preferably a 25V Zener diode.

Wherein, the third transistor Q3 is used to cooperate with the ZD to stabilize the voltage. When the operating current of the liquid crystal tablet device is less than 100mA, the current selection range of the third transistor Q3 is 200mA-500mA.

To sum up, as an example, the circuit diagram of the liquid crystal tablet device provided in this embodiment is shown in FIG. Diode D3, fourth diode D4, fifth diode D5, sixth diode D6, second capacitor C2, Zener diode ZD and third transistor Q3.

Embodiment four

Fig. 7 is a flow chart of the erasing method of the liquid crystal tablet device provided by the fourth embodiment of the present invention, which is applicable to the handwriting device and the liquid crystal tablet device provided by any embodiment of the present invention. The method specifically includes:

Step 710, the handwriting device transmits power to the liquid crystal tablet device through wireless power transmission;

Step 730, the liquid crystal tablet device drives and erases the displayed content of the liquid crystal tablet device according to the electric energy transmitted by the handwriting device.

Wherein, for example, reference may be made to the circuit of the liquid crystal tablet device shown in FIG. 6 and the circuit of the handwriting device shown in FIG. 4 , and step 710 specifically includes the following steps:

The switch 102 is turned on; the power transmission circuit 103 is turned on; the power transmission drive circuit 104 is powered on; the power transmission drive circuit 104 outputs an electrical signal to the power transmission coil 105 .

The power transmitting coil 105 interacts with the power receiving coil 201, and the power receiving coil 201 generates alternating current.

Step 730 specifically includes:

The power receiving drive circuit 202 converts the alternating current into direct current and outputs it to the thin-film electrode, and the content displayed on the liquid crystal tablet device is cleared.

Further, when the power transmission circuit 103 is turned on, the control unit 107 is powered on, the control unit 107 detects whether the switch 102 is turned on, and when the switch 102 is turned on, sends a first control signal to the power transmission circuit 103 to control the power transmission circuit 103 is continuously turned on.

Specifically, after the control unit 107 is powered on, it monitors the turn-on time of the switch 102. If the turn-on time of the switch 102 is longer than the preset time, the control unit 107 stops sending the first control signal; if the turn-on time of the switch 102 is less than the preset duration, the control unit 107 continues to send the first control signal to the power transmission circuit 103 until the power transmission circuit 103 is turned on for a duration greater than or equal to the preset duration, the control unit 107 sends a second control signal to the power transmission circuit 103 to control the power transmission circuit 103 The electrical circuit 103 is turned off;

Wherein, the preset duration is greater than or equal to the minimum duration for which the liquid crystal tablet device needs to be powered on to erase the displayed content.

Exemplarily, in combination with the circuit shown in FIG. 4 , taking the first transistor Q1 as an NPN transistor and the second transistor Q2 as a PNP transistor as an example, the wiping operation of the liquid crystal tablet device provided by the embodiment of the present invention will be described. The specific process of the removal method. Wherein, when the switch S1 (that is, the switch 102) is not pressed, that is, when the switch S1 is turned off, due to the pull-up effect of the second resistor R2, the base of the first transistor Q1 is at a high level, and the first transistor Q1 Q1 is in an off state; due to the pull-down effect of the fourth resistor R4, the base of the second transistor Q2 is at a low level, and the second transistor Q2 is in an off state. At this time, the power transmission drive circuit 104 has no power supply and does not output electrical signals. When the switch S1 is pressed, that is, when the switch S1 is turned on, the base of the first triode Q1 is at a low level, the first triode Q1 is turned on, and the voltage at the output terminal of the power supply 101 is provided to the power transmission drive circuit 104 to send The electric drive circuit 104 is powered on, and outputs an electric signal; the voltage at the output end of the power supply 101 is converted by the power conditioning circuit 106, and then output to the control unit 107, and the control unit 107 is powered on, and the control unit 107 can output a control signal to the power transmission drive circuit 104, The frequency of the electrical signal output by the power transmission drive circuit 104 is controlled so that the frequency of the electrical signal output by the power transmission drive circuit 104 meets the requirements, and the power transmission coil 105 and the power receiving coil 201 can act, and the power receiving coil 201 generates alternating current. After the control unit 107 is powered on, it can output a high-level signal to the common connection terminal of the third resistor R3 and the fourth resistor R4, the base of the second transistor Q2 is at a high level, the second transistor Q2 is turned on, and the second transistor Q2 is turned on. The base of the triode Q1 is at a low level, which controls the first triode Q1 to be continuously turned on. At this time, even if the switch S1 is turned off, the control unit 107 can control the first triode Q1 to be continuously turned on. Specifically, the control unit 107 detects whether the conduction duration of the switch S1 reaches a preset duration, for example, detects whether the conduction duration of the switch S1 reaches 2s. When the conduction duration of the switch S1 is less than the preset duration, the control unit 107 continues to output high The level signal is sent to the common connection terminal of the third resistor R3 and the fourth resistor R4, and the second transistor Q2 is turned on, thereby controlling the first transistor Q1 to be continuously turned on. When the conduction period of the first transistor Q1 is longer than the preset duration, the control unit 107 outputs a low-level signal to the common connection terminal of the third resistor R3 and the fourth resistor R4, and the second transistor Q2 is turned off; Due to the pull-up effect of the second resistor R2, the base of the first transistor Q1 is at a high level, and the first transistor Q1 is turned off. If the control unit 107 detects that the switch S1 is turned on for a preset duration, the control unit 107 stops outputting a high-level signal to the common connection terminal of the third resistor R3 and the fourth resistor R4, or outputs a low-level signal to the third resistor R3. At the common connection end of the resistor R3 and the fourth resistor R4, the second transistor Q2 is turned off; since the switch S1 is still turned on, the base of the first transistor Q1 is at a low level, and the first transistor Q1 is continuously turned on . If the switch S1 is turned off at a subsequent time, due to the pull-up effect of the second resistor R2, the base of the first transistor Q1 is at a high level, and the first transistor Q1 is turned off, that is, when the switch S1 is turned off, The first triode Q1 is turned off, and the entire power transmission circuit 103 is turned off.

It should be noted that, since the erasing of the displayed content on the liquid crystal tablet device requires the duration of output voltage to the liquid crystal film electrode to meet certain requirements, the duration of the conduction of the power transmission circuit needs to meet certain requirements, and then provide power to the power transmission coil. The duration of the signal meets certain requirements. Therefore, the preset duration needs to be greater than or equal to the minimum duration that the liquid crystal tablet device needs to be powered on to erase the displayed content.

Wherein, as an example, in combination with the circuit diagram of the liquid crystal tablet device shown in FIG. 6 in Embodiment 3, specifically, the power receiving coil L2 receives the AC signal sent by the power transmitting coil L1, and the AC signal is removed by the first capacitor C1 After glitch interference, the bridge rectifier circuit BD composed of the third diode D3, the fourth diode D4, the fifth diode D5 and the sixth diode D6 and the second capacitor C2 convert the AC signal into a DC The signal, the direct current signal is stably output to the liquid crystal thin film electrode after being stabilized by the Zener diode ZD and the third triode Q3, so that the content displayed on the liquid crystal tablet device is cleared.

In the technical solution provided by this embodiment, the power provided by the power supply provided in the handwriting device is sent to the liquid crystal tablet device through wireless power transmission, and the liquid crystal tablet device drives and erases the liquid crystal tablet according to the power transmitted by the handwriting device. The display content of the device solves the problem that the liquid crystal writing board device cannot be sealed due to the existence of power supply, switch, etc., and cannot be dustproof and waterproof, so that the liquid crystal writing board device can be applied to many occasions; at the same time, through the use of erasing The way that the switch is separated from the tablet can avoid accidental erasure of the written content on the tablet and improve the flexibility of the tablet.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention, and the present invention The scope is determined by the scope of the appended claims.

Claims (13)

1. a kind of handwriting device, it is characterised in that including power supply, switch, power transmission circuit, power transmission drive circuit and power transmission coil；

The input of the power transmission circuit is electrically connected with the output end of the power supply, and output end and the power transmission of the power transmission circuit are driven The power input electrical connection of dynamic circuit, the first control terminal of the power transmission circuit electrically connects with the switch, for according to institute The control for stating switch transmits the voltage of the output end of the power supply to the power input of the power transmission drive circuit；

The output end of the power transmission drive circuit electrically connects with the power transmission coil, for after the power-up, to the power transmission coil Export electric signal；

The power transmission coil is used for when being applied in corresponding electric signal, is acted on neighbouring electricity reception coil, makes described by electric wire Circle produces alternating current.

2. handwriting device according to claim 1, it is characterised in that also including power supply modulate circuit and control unit；

The input of the power supply modulate circuit electrically connects with the output end of the power transmission circuit, the power supply modulate circuit it is defeated Go out end to electrically connect with described control unit, for when the power transmission circuit turns on, the power transmission circuit output end to be exported Powered after voltage conversion to described control unit；

Described control unit, electrically connected with the second control terminal of the power transmission circuit, it is described for after working on power, detecting During the conducting of switch, the power transmission circuit is controlled to turn on, and to the power transmission drive circuit output control signal, with described in control Power transmission drive circuit exports the frequency of electric signal.

3. handwriting device according to claim 2, it is characterised in that the power transmission circuit includes：First triode, second Triode, the first diode, the second diode, first resistor, second resistance, 3rd resistor and the 4th resistance；

First pole of first triode electrically connects with the input of the power transmission circuit, the second pole of first triode Electrically connected with the output end of the power transmission circuit, the base stage of first triode passes through the first resistor and the described 2nd 3 The second pole electrical connection of pole pipe；

One end of the second resistance electrically connects with the first pole of first triode, the other end of the second resistance and institute State the base stage electrical connection of the first triode；

The first pole ground connection of second triode, the base stage of second triode pass through the 3rd resistor and the control The output end electrical connection of unit；

One end of 4th resistance connects with one end that the 3rd resistor is connected with described control unit；4th resistance The other end ground connection；

First pole of first diode electrically connects with the second pole of second triode, and the second of first diode Pole electrically connects with the first control terminal of the power transmission circuit；

First pole of second diode electrically connects with described control unit, the second pole of second diode and described the The first pole electrical connection of one diode.

4. handwriting device according to claim 2, it is characterised in that the power transmission drive circuit uses LT4531.

5. handwriting device according to claim 4, it is characterised in that the frequency of the power transmission drive circuit output signal is 0.25Hz。

6. handwriting device according to claim 1, it is characterised in that the switch is key switch.

7. a kind of liquid crystal handwriting board device, it is characterised in that including electricity reception coil and by electric drive circuit；

The electricity reception coil is used for and power transmission coil effect produces alternating current；

The input by electric drive circuit electrically connects with the electricity reception coil, the output end and liquid by electric drive circuit Membrane electrode electrical connection on brilliant handwriting board device, for the alternating current in the electricity reception coil to be converted into direct current and exported To the membrane electrode, to wipe the content that liquid crystal handwriting board device is shown.

8. liquid crystal handwriting board device according to claim 7, it is characterised in that also including the first electric capacity；

First electric capacity is parallel to the both ends of the electricity reception coil；

It is described to be included bridge rectifier and the second electric capacity, two inputs point of the bridge rectifier by electric drive circuit Both ends not with the electricity reception coil electrically connect, two output ends of the bridge rectifier respectively with two membrane electrode electricity Connection；

Second electric capacity is parallel to two output ends of the bridge rectifier.

9. liquid crystal handwriting board device according to claim 8, it is characterised in that also including voltage-regulator diode and the three or three pole Pipe；

The first pole and the second pole of 3rd triode electrically connect with two output ends of the bridge rectifier respectively；

First pole of the voltage-regulator diode electrically connects with the base stage of the 3rd triode, the second pole of the voltage-regulator diode Electrically connected with the second pole of the 3rd triode.

10. a kind of method for deleting of liquid crystal handwriting board device, it is characterised in that filled suitable for handwriting device and liquid crystal handwriting pad Put, including：

Handwriting device is by wireless power delivery mode to the liquid crystal handwriting board device power transmission；

The electrical energy drive that liquid crystal handwriting board device transmits according to the handwriting device wipes the display content of liquid crystal handwriting board device.

11. the method for deleting of liquid crystal handwriting board device according to claim 10, it is characterised in that the handwriting device bag Include power supply, switch, power transmission circuit, power transmission drive circuit and power transmission coil；The input of the power transmission circuit and the power supply Output end electrically connects, and the output end of the power transmission circuit electrically connects with the power input of power transmission drive circuit, the power transmission electricity First control terminal on road electrically connects with the switch, and the output end of the power transmission drive circuit electrically connects with the power transmission coil；

Liquid crystal handwriting board device includes electricity reception coil and by electric drive circuit；The input by electric drive circuit with it is described by Electric coil electrically connects, and the output end by electric drive circuit electrically connects with the membrane electrode on liquid crystal handwriting board device；

The method for deleting includes：

During the switch conduction, the power transmission circuit turns on, electricity on the power transmission drive circuit, the power transmission drive circuit output Electric signal is to the power transmission coil；

The power transmission coil acts on the electricity reception coil, and the electricity reception coil produces alternating current；

It is described that the alternating current is converted into direct current by electric drive circuit and exported to the membrane electrode, liquid crystal handwriting pad dress Put the content erasing of display.

12. method for deleting according to claim 11, it is characterised in that the handwriting device also includes power supply modulate circuit And control unit；

The input of the power supply modulate circuit electrically connects with the output end of the power transmission circuit, the power supply modulate circuit it is defeated Go out end to electrically connect with described control unit；

Described control unit electrically connects with the second control terminal of the power transmission circuit；

The method for deleting also includes：

During the power transmission circuit conducting, whether electricity in described control unit, the described control unit detection switch turns on, in institute When stating switch conduction, the first control signal is sent to the power transmission circuit, to control the power transmission circuit constant conduction.

13. method for deleting according to claim 12, it is characterised in that in described control unit after electricity, opened described in monitoring The duration of conducting is closed, if the duration of the switch conduction is more than preset duration, described control unit stops sending described first Control signal；If the time of the switch conduction is less than the preset duration, described control unit is held to the power transmission circuit Supervention send the first control signal, until when the duration of power transmission circuit conducting is more than or equal to the preset duration, the control Unit sends the second control signal to the power transmission circuit, to control the power transmission circuit to turn off；

Wherein, when the preset duration is more than or equal to the minimum that the content needs that liquid crystal handwriting board device erasing is shown are powered It is long.