Voltage regulating circuit for locally erasing liquid crystal blackboard and control method of voltage regulating circuit

Abstract

The invention discloses a voltage regulating circuit for locally erasing a liquid crystal blackboard and a control method of the voltage regulating circuit. The voltage regulating circuit is particularly suitable for regulating liquid crystal driving voltage in the locally erasing liquid crystal blackboard. By defining a plurality of gesture position areas on the liquid crystal blackboard, a user can operate at the positions by pressing the blackboard eraser so as to trigger a voltage adjusting instruction.

Description

Technical Field

[0001] The present invention relates to the technical field of local erasing liquid crystal blackboards, and particularly to a voltage regulating circuit for a local erasing liquid crystal blackboard and a control method thereof. Background Art

[0002] In existing liquid crystal writing blackboards, especially those with local erasing functions, there is a common and significant problem: the driving voltage of the liquid crystal film needs to be adjusted according to changes in ambient temperature. If the voltage is set improperly, the following problems may occur:

[0003] Incomplete local erasure: The response speed and transparency of the liquid crystal film are affected by temperature. If the driving voltage is inappropriate, the erasing effect may be poor, and residual traces cannot be completely removed.

[0004] Cross-region phenomenon: Since the sensitivities of liquid crystal films in different regions to voltage changes are different, if the voltage is set unreasonably, areas outside the erasing region may be accidentally erased.

[0005] To solve the above problems, existing designs usually add an analog adjustable potentiometer to the circuit to manually adjust the driving voltage of the liquid crystal film. However, this method has the following obvious defects:

[0006] Damaged appearance aesthetics: To install the external potentiometer, the whole machine shell needs to be drilled, which not only affects the overall aesthetics of the device but also may damage its sealing and protection performance.

[0007] Inconvenient for users to adjust: When users adjust the potentiometer, they cannot intuitively know the specific value of the current voltage and can only find the appropriate voltage value through repeated trials. This trial-and-error process is inefficient and has a poor user experience.

[0008] Reliability issues: As a mechanical component, the analog potentiometer is prone to wear or poor contact after long-term use, resulting in the inability to normally adjust the driving voltage of the liquid crystal film. Once the potentiometer fails, it will directly affect the normal operation of liquid crystal writing, and even cause problems such as incomplete local erasure or cross-region.

[0009] In view of the above problems, there is an urgent need to develop a more intelligent, reliable, and easy-to-operate voltage regulating circuit control method to ensure that the liquid crystal writing blackboard can achieve an ideal erasing effect under various environmental conditions and improve the user experience. Summary of the Invention

[0010] The present invention provides a voltage regulating circuit for a local erasing liquid crystal blackboard and a control method thereof, aiming to solve the problems existing in the prior art, specifically including the following:

[0011] A voltage regulating circuit for a local erasing liquid crystal blackboard. The voltage regulating circuit includes a position information confirmation circuit, an MCU control circuit, a voltage control circuit, a voltage level prompting circuit, a negative voltage generating circuit, and a liquid crystal blackboard driving circuit. The connection relationships of each part are as follows:

[0012] Position information confirmation circuit: Obtains the position information of the user pressing the blackboard eraser and transmits it to the MCU control circuit.

[0013] MCU control circuit: Receives the position information and makes a voltage regulation judgment, and then transmits the regulated voltage signals to the voltage control circuit, the voltage level prompting circuit, and the liquid crystal blackboard driving circuit respectively.

[0014] Voltage control circuit: Adjusts the output voltage according to the control signal of the MCU and transmits the signal to the negative voltage generating circuit.

[0015] Negative voltage generating circuit: Generates a corresponding negative voltage according to the voltage regulation signal transmitted by the voltage control circuit and transmits it to the liquid crystal blackboard driving circuit.

[0016] Liquid crystal blackboard driving circuit: Drives the liquid crystal film according to the received voltage signal to achieve the voltage regulation function.

[0017] Voltage level prompting circuit: Uses one or more of a buzzer circuit, a speaker circuit, a display circuit, and a warning light circuit to prompt the current voltage level.

[0018] The present invention also provides a control method for a voltage regulating circuit of a local erasing liquid crystal blackboard, including the following steps:

[0019] S1 Define gesture position areas: Define several gesture position areas on the liquid crystal blackboard, and each position area corresponds to a specific coordinate range (lower left corner, lower right corner, upper right corner, upper left corner, middle top, and middle bottom).

[0020] S2 User operation: The user operates in these position areas by pressing the blackboard eraser to trigger a voltage adjustment instruction.

[0021] S3 Obtain position information: The position information confirmation circuit obtains the position information of the user pressing the blackboard eraser and transmits it to the MCU control circuit.

[0022] S4 Voltage regulation judgment: The MCU judges the user's gesture action according to the preset coordinate range and time range to determine whether to increase or decrease the voltage.

[0023] S5 Send a control signal: If the MCU judgment result meets the step-up or step-down condition, the MCU outputs a control signal to the voltage control circuit through the GPIO port.

[0024] S6 Voltage Adjustment: The voltage control circuit adjusts the liquid crystal driving voltage according to the control signal of the MCU, and finally realizes the voltage change through the negative voltage generation circuit.

[0025] Position Area Coordinate Range:

[0026] The lower left corner of the liquid crystal blackboard is the coordinate origin (0, 0). The length of the horizontal X-axis writing area of the liquid crystal blackboard is L, and the height of the vertical Y-axis is H. The position area is a circular area for placing the blackboard eraser, with a diameter of n, and n is greater than the diameter of the blackboard eraser;

[0027] The specific coordinate range of the position area is:

[0028] The coordinate range of position 1 at the lower left corner is (X1≤n, Y1≤n);

[0029] The coordinate range of position 2 at the lower right corner is (X2≥L - n, Y2≤n);

[0030] The coordinate range of position 3 at the upper right corner is (X3≥L - n, Y3≥H - n);

[0031] The coordinate range of position 4 at the upper left corner is (X4≤n, Y4≥H - n);

[0032] The coordinate range of position 5 at the middle top is (L / 2 - n≤X5≤L / 2 + n, Y5≥H - n);

[0033] The coordinate range of position 6 at the middle bottom is (L / 2 - n≤X6≤L / 2 + n, Y6≤n).

[0034] User Operations and Feedback:

[0035] When the user presses position 5, it means increasing the voltage by one gear, and pressing position 6 means decreasing the voltage by one gear.

[0036] The buzzer feedback mechanism is used to prompt the current voltage gear. For example, after each voltage adjustment, the buzzer emits a corresponding number of beeps to confirm the current voltage gear.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] Intelligent Voltage Regulation: The automatic voltage regulation is realized through the MCU control circuit, avoiding the inconvenience and errors caused by manual adjustment, and improving the accuracy and stability of voltage regulation.

[0039] Enhanced User Experience: The user does not need to manually adjust the potentiometer. Just pressing the specified position can complete the voltage adjustment. The operation is simple and fast, and the user experience is greatly improved.

[0040] Enhanced reliability: The vulnerable analog potentiometer is removed, and the voltage regulation function is realized by an electronic circuit, which extends the service life of the device and reduces the maintenance cost.

[0041] Maintaining aesthetic appearance: There is no need to drill holes in the shell for installing the potentiometer, which maintains the overall aesthetic appearance and sealing performance of the device. Description of the Drawings

[0042] Figure 1 Schematic diagram of the circuit structure in an embodiment of the present invention;

[0043] Figure 2 Schematic diagram of the buzzer circuit structure in an embodiment of the present invention;

[0044] Figure 3 Schematic diagram of the position difference marking of the liquid crystal blackboard in an embodiment of the present invention;

[0045] Figure 4 Flowchart of the control method of the voltage regulation circuit of the partial erasing liquid crystal blackboard in an embodiment of the present invention. Detailed Embodiments

[0046] 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 creative efforts shall fall within the protection scope of the present invention.

[0047] Please refer to Figure 1, the present invention provides a voltage regulating circuit for a locally erasable liquid crystal blackboard, which includes a position information confirmation circuit, an MCU control circuit, a voltage control circuit, a voltage level indication circuit, a negative voltage generation circuit, and a liquid crystal blackboard driving circuit. The input end of the MCU control circuit is connected to the position information confirmation circuit, and the three output ends of the MCU control circuit are respectively connected to the voltage control circuit, the voltage level indication circuit, and the liquid crystal blackboard driving circuit. The input end of the negative voltage generation circuit is connected to the voltage control circuit, and the output end of the negative voltage generation circuit is connected to the liquid crystal blackboard driving circuit. In this embodiment, the position information confirmation circuit adopts the form of an infrared sensor processing circuit. This circuit consists of an infrared emitting diode and an infrared receiving diode, which work together to determine the position of an object by emitting and receiving infrared signals. When the eraser is placed in the blackboard, it will block part of the infrared signals, thus changing the signal intensity and mode received by the receiving diode. The processor circuit will analyze and process this signal change, and finally calculate the coordinate information of the eraser on the X-axis and Y-axis. This positioning method using infrared sensing technology has the characteristics of high precision and fast response, and can accurately obtain the real-time position of the blackboard eraser, providing a reliable data basis for subsequent voltage regulation operations. In addition to the infrared sensor processing circuit, according to actual needs, the position information confirmation circuit can also adopt common circuit forms for positioning and confirming coordinates, such as capacitive screens, electromagnetic screens, ultrasonic positioning, or magnetic induction positioning. For example, capacitive screen positioning determines the position by detecting the change in capacitance between the touch point and the screen, and has the advantages of sensitive touch and convenient operation, and is suitable for environments that require direct touch operations; electromagnetic screen positioning uses the principle of electromagnetic induction to determine the position through the interaction between the electromagnetic pen and the screen, and has high precision and stability, and is commonly used in application scenarios such as high-precision graphic design; ultrasonic positioning judges the distance and orientation by emitting and receiving ultrasonic signals, can achieve non-contact measurement, and is not affected by environmental factors such as light, and is suitable for various complex environments; magnetic induction positioning determines the position through the change of the magnetic field, and has good anti-interference ability and stability, and is commonly used in some special occasions.

[0048] The MCU control circuit plays a core control role in the entire voltage regulating circuit. Its input end is closely connected to the position information confirmation circuit, and can accurately receive the eraser position information transmitted from the position information confirmation circuit. Based on this position information, the MCU control circuit will perform complex voltage regulation judgment operations. It not only simply determines the voltage adjustment according to the position, but also comprehensively considers various factors, such as the current voltage state, the display content of the blackboard, etc. After precise judgment, the MCU control circuit will transmit the voltage regulation signals to the voltage level indication circuit, the voltage control circuit, and the liquid crystal blackboard driving circuit respectively. These voltage regulation signals contain key information such as the direction and amplitude of voltage adjustment, ensuring that the entire system can accurately adjust the voltage according to actual needs, so as to effectively control the local erasing function of the liquid crystal blackboard.

[0049] There are n voltage control circuits in this embodiment. The importance of these voltage control circuits is self-evident. They are the key components to achieve precise voltage control. Each voltage control circuit undertakes a specific task. According to the voltage regulation signal transmitted by the MCU control circuit, it finely adjusts the voltage. They can work independently or cooperate with each other to meet the voltage adjustment requirements in different situations. The main function of the voltage control circuit is to control and adjust the voltage according to the voltage regulation signal. When receiving the voltage regulation signal from the MCU control circuit, the voltage control circuit will quickly respond and adjust the voltage by precisely controlling the internal circuit components. For example, it can increase or decrease the voltage output according to the signal indication, and adjust parameters such as the waveform and frequency of the voltage. The voltage signal adjusted by the voltage control circuit will be transmitted to the negative voltage generation circuit, providing accurate control instructions for the negative voltage generation circuit to ensure that it can generate the required negative voltage, so as to provide a suitable working voltage for the liquid crystal blackboard driving circuit and ensure the normal operation of the local erasure function.

[0050] The input end of the negative voltage generation circuit is closely connected to the voltage control circuit. Its function is to receive the voltage regulation signal from the voltage control circuit. According to these voltage regulation signals, the negative voltage generation circuit will use specific electronic circuit technologies and components, such as transistors, operational amplifiers, etc., and through a series of conversion and adjustment processes, generate the corresponding negative voltage. The magnitude and stability of this negative voltage directly affect the effect and quality of the local erasure of the liquid crystal blackboard. The generated negative voltage will then be transmitted to the liquid crystal blackboard driving circuit, providing the necessary working voltage for the liquid crystal blackboard driving circuit to enable it to accurately drive the liquid crystal molecules to deflect and achieve the local erasure function.

[0051] Please refer to Figure 2, in this embodiment, the voltage gear indication circuit adopts the form of a buzzer circuit. This circuit is jointly composed of a buzzer device BUZ1, a triode Q12, a resistor R70, and a capacitor C53. The resistor R70 plays an important role in voltage division and current limiting in the circuit. It can limit the magnitude of the current passing through the base of the triode, protecting the triode from the impact of excessive current, and at the same time providing a stable operating point for the entire circuit. The capacitor C53 is a voltage stabilizing and filtering capacitor. It can absorb the voltage fluctuations in the circuit, making the voltage supplied to the buzzer more stable, thereby ensuring that the sound emitted by the buzzer is clear and stable. When the MCU needs to increase or decrease the voltage, it will send a control signal to the base of the triode Q12 through the GPIO control port. Due to the amplification effect of the triode, this control signal will be amplified at the collector of the triode, generating sufficient current to drive the buzzer BUZ1 to sound. The number of times the buzzer sounds is precisely controlled by the CPU of the liquid crystal blackboard according to the gear data. In this way, users can intuitively understand the change of the current voltage gear through the number of times the buzzer sounds, providing convenient operation feedback for users. In addition to the buzzer circuit, the voltage gear indication circuit can also select forms such as a speaker circuit, a display circuit, or a warning light circuit. The speaker circuit can inform users of the change of the voltage gear by playing different frequencies or voice prompts, with a stronger ability to convey information; the display circuit can directly display the current voltage gear information on the screen, such as numbers, icons, etc., and users can obtain relevant information at a glance; the warning light circuit is to prompt users of the current voltage gear through lights of different colors or flashing modes, and can also prompt the current voltage gear according to the number of set LED lights, with the characteristics of simplicity, intuitiveness, and easy recognition. These different prompting methods can be selected or combined according to actual application requirements and user experience.

[0052] Please refer to Figure 3 and Figure 4 , the present invention provides a voltage regulation circuit control method for a partial erasure liquid crystal blackboard, which realizes voltage adjustment through specific gesture position areas and user operations. This method ensures the accuracy of voltage adjustment and the convenience of user operations, avoiding abnormal voltage changes caused by misoperations.

[0053] Specific steps:

[0054] S1 Define gesture position areas Define several gesture position areas on the liquid crystal blackboard, and each position area corresponds to a specific coordinate range. These position areas are used to place the blackboard eraser and trigger corresponding voltage adjustment instructions.

[0055] Lower left corner position 1: (X1≤n, Y1≤n);

[0056] Lower right corner position 2: (X2≥L - n, Y2≤n);

[0057] Upper right corner position 3: (X3≥L - n, Y3≥H - n);

[0058] Upper left corner position 4: (X4≤n, Y4≥H - n);

[0059] Middle top position 5: (L / 2 - n≤X5≤L / 2 + n, Y5≥H - n);

[0060] Middle bottom position 6: (L / 2 - n≤X6≤L / 2 + n, Y6≤n);

[0061] Wherein, the lower left corner of the liquid crystal blackboard is the coordinate origin (0, 0), the length of the writing area on the horizontal X - axis is L, the height of the vertical Y - axis is H, the position area is a circular area for placing the blackboard eraser, the diameter is n, and n is greater than the diameter of the blackboard eraser.

[0062] S2 User operation The user operates by pressing the blackboard eraser within the position area defined above to trigger a voltage adjustment instruction. For example:

[0063] Boost one gear: Press positions 1, 2, 3, 4, 5 in sequence.

[0064] Lower one gear: Press positions 1, 2, 3, 4, 6 in sequence.

[0065] S3 Obtain position information The position information confirmation circuit obtains the position information of the user pressing the blackboard eraser and transmits it to the MCU control circuit.

[0066] S4 Voltage regulation judgment The MCU judges the user's gesture action according to the preset coordinate range and time range to determine whether to increase or decrease the voltage. The specific judgment process includes:

[0067] Judge whether the blackboard eraser appears at positions 1, 2, 3, 4 in sequence.

[0068] Whether the last press is at position 5 (boost) or position 6 (lower).

[0069] Check whether the timer times out. If it times out, return to the normal state.

[0070] S5 Send control signal If the MCU judgment result meets the boost or lower voltage condition, the MCU outputs a control signal to the voltage control circuit through the GPIO port.

[0071] The S6 voltage adjustment voltage control circuit adjusts the liquid crystal driving voltage according to the control signal of the MCU, and finally realizes the voltage change through the negative voltage generation circuit. At the same time, the MCU sends a control signal to the buzzer to inform the user of the current voltage level by the number of ringing times (for example, ringing 5 times means the voltage is at level 5).

[0072] The specific operation steps are as follows:

[0073] 1. Initial position (Gesture 1): Press the blackboard eraser at position 1 in the lower left corner.

[0074] 2. Lower right corner position (Gesture 2): Then press position 2.

[0075] 3. Upper right corner position (Gesture 3): Then press position 3.

[0076] 4. Upper left corner position (Gesture 4): Then press position 4.

[0077] 5. Final selection position (Gesture 5): If you want to increase the voltage by one level, press position 5 (the middle top).

[0078] If you want to decrease the voltage by one level, press position 6 (the middle bottom).

[0079] After each press, you will hear the buzzer beep several times, indicating the current voltage level. For example, beeping 2 times means the voltage is at level 2, beeping 5 times means the voltage is at level 5, and so on. In this way, the user can decide whether to adjust the voltage according to the erasing effect, so as to achieve an ideal erasing effect.

[0080] Figure 4 Shows the software flow chart of the blackboard gesture voltage regulation control method for local erasing of the liquid crystal film. The following are the detailed steps:

[0081] 1. Normal working state: The blackboard is in a normal working state, waiting for user operation.

[0082] 2. Detect position 1: Determine whether the coordinates of the blackboard eraser are within the coordinate range of position 1 (X1≤n, Y1≤n). If not, return to the normal state; if so, turn on the timer to start timing.

[0083] 3. Detect position 2: Continue to determine whether the coordinates of the blackboard eraser are within the coordinate range of position 2 (X2≥L - n, Y2≤n). If not, return to the normal state; if so, continue to the next step.

[0084] 4. Detect position 3: Determine whether the coordinates of the blackboard eraser are within the coordinate range of position 3 (X3≥L - n, Y3≥H - n). If not, return to the normal state; if so, continue to the next step.

[0085] 5. Detection position 4: Determine whether the coordinates of the blackboard eraser are within the coordinate range of position 4 (X4 ≤ n, Y4 ≥ H - n). If not, return to the normal state; if so, proceed to the next step.

[0086] 6. Detection of position 5 or position 6:

[0087] If the coordinates of the blackboard eraser are within the range of position 5 (L / 2 - n ≤ X5 ≤ L / 2 + n, Y5 ≥ H - n), check whether the timer has timed out. If not, notify the MCU to increase the voltage by one level and emit the corresponding buzzer sound prompt (for example, if it is currently at level 5, it will sound 5 times).

[0088] If the coordinates of the blackboard eraser are within the range of position 6 (L / 2 - n ≤ X6 ≤ L / 2 + n, Y6 ≤ n), check whether the timer has timed out. If not, notify the MCU to decrease the voltage by one level and emit the corresponding buzzer sound prompt (for example, if it was previously at level 5 and now decreases by one level, it will sound 4 times).

[0089] 7. Timeout handling: If the timer times out in any step, return to the normal state to prevent misoperation.

[0090] Through the above process, the MCU microprocessor can accurately judge the user's gesture actions and perform corresponding voltage adjustments to ensure the best erasing effect. The invention realizes precise control of the driving voltage of the liquid crystal blackboard through a simple and intuitive gesture voltage regulation method. This method not only improves the user's operation experience but also effectively avoids abnormal voltage changes caused by misoperation, ensuring the normal use and maintenance of the blackboard.

[0091] 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 premise that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions 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.

[0092] The above are only partial or preferred embodiments of the present invention. Whether in terms of text or drawings, they cannot limit the scope of protection of the present invention. 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 voltage regulating circuit for partially erasing a liquid crystal blackboard, characterized in that: It includes a position information confirmation circuit, an MCU control circuit, a voltage control circuit, a voltage gear prompt circuit, a negative voltage generating circuit, and a liquid crystal blackboard driving circuit. The input end of the MCU control circuit is connected to the position information confirmation circuit, and the three output ends of the MCU control circuit are respectively connected to the voltage control circuit, the voltage gear prompt circuit, and the liquid crystal blackboard driving circuit. The input end of the negative voltage generating circuit is connected to the voltage control circuit, and the output end of the negative voltage generating circuit is connected to the liquid crystal blackboard driving circuit. Among them, the position information confirmation circuit transmits the acquired position information to the MCU control circuit, the MCU control circuit makes a voltage regulation judgment based on the transmitted position information, and transmits the determined voltage regulation signal to the voltage gear prompt circuit, the voltage control circuit, and the liquid crystal blackboard drive circuit respectively, the voltage control circuit transmits the signal to the negative voltage generating circuit, and the negative voltage generating circuit generates a corresponding voltage according to the voltage regulation signal transmitted by the voltage control circuit and transmits it to the liquid crystal blackboard drive circuit.

2. The voltage regulating circuit for partially erasing a liquid crystal blackboard according to claim 1, characterized in that: The voltage position prompt circuit is one or more of a buzzer circuit, a speaker circuit, a display circuit, and a prompt light circuit.

3. The voltage regulating circuit for partially erasing a liquid crystal blackboard according to claim 2, characterized in that: The voltage position prompt circuit is a buzzer circuit, which is composed of a buzzer device BUZ1, a transistor Q12, a resistor R70, and a capacitor C53. The resistor R70 is a voltage-dividing and current-limiting resistor, and the capacitor C53 is a voltage-stabilizing and filtering capacitor.

4. The voltage regulating circuit for partially erasing a liquid crystal blackboard according to claim 1, characterized in that: The voltage regulating circuit for partially erasing the liquid crystal blackboard includes at least one voltage control circuit.

5. A control method for a voltage regulating circuit for partially erasing a liquid crystal blackboard, characterized in that: The following steps are involved: S1: define several gesture position areas on the LCD blackboard, the position areas include the lower left corner, the lower right corner, the upper right corner, the upper left corner, the middle top and the middle bottom, each position area corresponds to a specific coordinate range; S2: The user operates in these position areas by pressing the blackboard eraser to trigger a voltage adjustment instruction; S3: The position information confirmation circuit obtains the position information of the user pressing the blackboard eraser, and transmits the information to the MCU on the MCU control circuit; S4: The MCU determines the user's gesture action based on the preset coordinate range and time range, and determines whether the voltage needs to be increased or decreased; S5: If the MCU determines that the result meets the voltage boost or voltage reduction condition, the MCU outputs a control signal to the voltage control circuit through the GPIO port; S6: The voltage control circuit adjusts the liquid crystal driving voltage according to the control signal of the MCU, and finally realizes the voltage change through the negative voltage generating circuit.

6. The control method of the voltage regulating circuit for partially erasing a liquid crystal blackboard according to claim 5, characterized in that: The lower left corner of the LCD blackboard is the coordinate origin (0, 0), the horizontal X-axis writing area length of the LCD blackboard is L, the vertical Y-axis height is H, the position area is a circular area for placing a blackboard eraser, the diameter is n, and n is greater than the diameter of the blackboard eraser; The specific coordinate range of the location area is: The coordinate range of the lower left corner position 1 is (X1≤n,Y1≤n); The coordinate range of the lower right corner position 2 is (X2≥Ln,Y2≤n); The coordinate range of the upper right corner position 3 is (X3≥Ln,Y3≥Hn); The coordinate range of the upper left corner position 4 is (X4≤n,Y4≥Hn); The coordinate range of the middle top position 5 is (L / 2-n≤X5≤L / 2+n,Y5≥Hn); The coordinate range of the middle bottom position 6 is (L / 2-n≤X6≤L / 2+n,Y6≤n).

7. The control method of the voltage regulating circuit for partially erasing a liquid crystal blackboard according to claim 6, characterized in that: The user presses position 5 to increase the voltage by one gear, and presses position 6 to decrease the voltage by one gear.

8. The control method of the voltage regulating circuit for partially erasing a liquid crystal blackboard according to claim 7, characterized in that: It also includes a buzzer feedback mechanism to indicate the current voltage level.

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