A method and system for increasing the erasing voltage of a liquid crystal writing device

Abstract

The present invention belongs to the field of erasing technology of liquid crystal writing devices, and specifically discloses a method and system for increasing the erasing voltage of a liquid crystal writing device, the method comprising: applying a first voltage V1 to all conductive areas on a first conductive layer, and applying a second voltage V2 to all conductive areas on a second conductive layer; controlling the drive outputs corresponding to all conductive areas on the first conductive layer to be in a high impedance state, maintaining the second voltage V2 applied to the conductive areas at a set position on the second conductive layer, and applying the first voltage V1 to the remaining conductive areas on the second conductive layer, so that the electric field at the corresponding position of the conductive area on the second conductive layer to which the second voltage V2 is applied is increased to be greater than the erasing start voltage of the cholesteric phase liquid crystal, thereby achieving erasing of the written content at the corresponding position. The present invention can increase the erasing voltage without destroying the original structure of the liquid crystal writing device, thereby increasing the service life of the product.

Description

Technical Field

[0001] The present invention relates to the field of erasing technology of liquid crystal writing devices, and in particular to a method and system for increasing the erasing voltage of a liquid crystal writing device. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Liquid crystal writing devices have been widely used in education, office and other fields, and have very good development prospects. The working principle is to utilize the characteristics of cholesteric liquid crystal. By applying pressure on the liquid crystal writing device, the cholesteric liquid crystal at the pressure application position changes from a focal-conic state to a planar state, thereby being able to record the writing pressure traces of the writing pen and display the corresponding writing content. By applying an electric field, the cholesteric liquid crystal is flipped, that is, changed from a planar state to a focal-conic state, so that the writing traces on the liquid crystal writing device disappear to achieve erasure.

[0004] The structure of a liquid crystal writing device generally includes a first conductive layer, a liquid crystal layer, and a second conductive layer arranged in sequence from top to bottom. By applying an electric field between the first conductive layer and the second conductive layer, the written content on the liquid crystal writing device can be erased.

[0005] In order to achieve local erasure of the liquid crystal writing device, the prior art divides the upper and lower conductive layers of the cholesteric liquid crystal into a plurality of mutually insulated conductive areas, and the conductive areas on the upper and lower conductive layers form a plurality of local erasing units at spatially overlapping positions. By applying a driving voltage to each conductive area, a set erasing electric field is formed on the local erasing unit corresponding to the position to be erased, thereby achieving local erasure of the writing at the position to be erased, while the writing at other positions remains unchanged.

[0006] In the prior art, the driving voltage is mostly generated by a driving chip. The higher the voltage output by the driving chip, the higher the required energy consumption. Therefore, it is expected to achieve the erasing effect with a lower driving voltage.

[0007] In addition, due to the limitations of the production process, the driving voltage generated by ordinary driver chips often has an upper limit. For example, the maximum voltage that the liquid crystal driver chip can output is mostly around 80V or 40V. Under normal circumstances, the driving voltage generated by the driver chip can fully meet the erasing requirements. However, because the cholesteric liquid crystal is exposed to ultraviolet rays, causing the liquid crystal molecules to decompose or the insulating layer to decompose, charged ions may be formed inside the liquid crystal, partially shielding the external electric field, causing the electric field that drives the cholesteric liquid crystal from a planar state to a focal conic state to increase with the use time. When the electric field required to drive the cholesteric liquid crystal to flip is greater than the upper limit of the driving voltage that the driver chip can generate, normal erasing cannot be achieved or the erasing effect is unsatisfactory, resulting in the product being unable to be used normally, which greatly affects the service life of the liquid crystal writing device. Summary of the invention

[0008] In order to solve the above problems, the present invention proposes a method and system for increasing the erasing voltage of a liquid crystal writing device. By utilizing the capacitance formed between the upper and lower conductive layers and controlling the voltage loading method, an erasing electric field higher than the voltage difference output by the driving chip to the upper and lower conductive layers can be formed in the target erasing area while keeping the output voltage of the driving chip unchanged, thereby ensuring the erasing effect and improving the product service life.

[0009] In some embodiments, the following technical solutions are adopted:

[0010] A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, the method comprising:

[0011] A first voltage V1 is applied to all conductive regions on the first conductive layer, and a second voltage V2 is applied to all conductive regions on the second conductive layer; wherein, , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0012] Control the drive outputs corresponding to all conductive areas on the first conductive layer to be in a high impedance state, and keep the conductive areas at set positions on the second conductive layer applying a second voltage The first voltage V1 is applied to the remaining conductive area on the second conductive layer, so that the second voltage V2 is applied to the second conductive layer. The electric field at the corresponding position of the conductive area is increased to be greater than the erasure start voltage of the cholesteric liquid crystal, thereby erasing the written content at the corresponding position.

[0013] In other embodiments, the following technical solutions are adopted:

[0014] A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, the method comprising:

[0015] A first voltage V1 is applied to all conductive regions on the second conductive layer, and a second voltage V2 is applied to all conductive regions on the first conductive layer; wherein, , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0016] By controlling the drive outputs corresponding to all the conductive areas on the second conductive layer to be in a high-impedance state, the second voltage V2 applied to the conductive areas at set positions on the first conductive layer remains unchanged, and the first voltage V1 is applied to the remaining conductive areas on the first conductive layer, the electric field at the positions corresponding to the conductive areas on the first conductive layer to which the second voltage V2 is applied is increased to a level greater than the erasure start voltage of the cholesteric liquid crystal, thereby achieving erasure of the written content at the corresponding positions.

[0017] As an optional solution, taking the second voltage V2 as the reference zero potential, the following conditions are satisfied:

[0018] .

[0019] As an optional solution, the written content at some positions is erased each time, thereby achieving complete erasure of all positions on the liquid crystal writing device.

[0020] As an optional solution, the voltages applied to the first conductive layer and the second conductive layer are interchanged according to a set time rule to prevent the liquid crystal from being passivated.

[0021] As an optional solution, the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually parallel strip-shaped conductive regions, and the conductive regions on the first conductive layer and the conductive regions on the second conductive layer are spatially perpendicular to each other.

[0022] In some embodiments, the following technical solutions are adopted:

[0023] A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, the method comprising:

[0024] Applying a first voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer ; Apply a second voltage to all conductive areas on the second conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0025] Control the drive output corresponding to the conductive area covered by the target erasing area on the first conductive layer to be in a high impedance state; apply a third voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, while the electric field in other areas is less than the erasing start voltage of the cholesteric liquid crystal; thereby erasing the written content in the target erasing area, while the written content in other areas remains unchanged; wherein, and is a constant not less than 0.

[0026] In other embodiments, the following technical solutions are adopted:

[0027] A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, the method comprising:

[0028] Applying a first voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ; Apply a second voltage to all conductive areas on the first conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0029] Control the drive output corresponding to the conductive area covered by the target erasing area on the second conductive layer to be in a high impedance state; apply a third voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, while the electric field in other areas is less than the erasing start voltage of the cholesteric liquid crystal; thereby erasing the written content in the target erasing area, while the written content in other areas remains unchanged; wherein, and is a constant not less than 0.

[0030] As an optional solution, the values ​​of a and b satisfy: a∈[0,1]; b=1.

[0031] As an optional solution, the values ​​of a and b satisfy: a∈[0.5, 2.2]; b∈[2a-0.5, 2a+0.5].

[0032] As an optional solution, the values ​​of a and b further satisfy:

[0033] a∈[0.8,0.9];b∈[1.6,1.8].

[0034] As an optional solution, the voltages applied to the first conductive layer and the second conductive layer are interchanged according to a set time rule to prevent the liquid crystal from being passivated.

[0035] As an optional solution, the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually parallel strip-shaped conductive regions, and the conductive regions on the first conductive layer and the conductive regions on the second conductive layer are spatially perpendicular to each other.

[0036] In other embodiments, the following technical solutions are adopted:

[0037] A writing film for increasing a local erasing voltage comprises a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually insulated conductive regions, and further comprises:

[0038] The control unit is configured to use the above method of increasing the erasing voltage of the liquid crystal writing device to achieve erasing of the target erasing area.

[0039] In other embodiments, the following technical solutions are adopted:

[0040] A method for increasing the erasing voltage of a liquid crystal writing device, wherein the liquid crystal writing device comprises a first conductive layer, a cholesteric liquid crystal layer, and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are not divided, and a fifth capacitor is externally connected to the first conductive layer; a fourth voltage is applied to the first conductive layer , a fifth voltage is applied to the second conductive layer , a fifth voltage is applied to the end of the fifth capacitor away from the first conductive layer , ; Vst is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0041] Control the corresponding drive output on the first conductive layer to be in a high impedance state; keep the voltage applied to the second conductive layer unchanged; apply a fourth voltage to the end of the fifth capacitor away from the first conductive layer ; It is possible to increase the electric field loaded between the first conductive layer and the second conductive layer to a level greater than the erasure start voltage of the cholesteric liquid crystal , thereby erasing all written content on the liquid crystal writing device.

[0042] In other embodiments, the following technical solutions are adopted:

[0043] A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer, and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer are not divided, and a seventh capacitor is externally connected to the second conductive layer;

[0044] Applying a fourth voltage to the second conductive layer , a fifth voltage is applied to the first conductive layer , a fifth voltage is applied to the end of the seventh capacitor away from the second conductive layer , ; V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0045] Control the corresponding drive output on the second conductive layer to be in a high impedance state; keep the voltage applied to the first conductive layer unchanged; apply a fourth voltage to the end of the seventh capacitor away from the second conductive layer ; It is possible to increase the electric field loaded between the first conductive layer and the second conductive layer to a level greater than the erasure start voltage of the cholesteric liquid crystal , thereby erasing all written content on the liquid crystal writing device.

[0046] In other embodiments, the following technical solutions are adopted:

[0047] A writing film for improving local erasing voltage comprises a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are not divided, and further comprises:

[0048] The control unit is configured to use the above method of increasing the erasing voltage of the liquid crystal writing device to achieve erasing of the written content.

[0049] In other embodiments, the following technical solutions are adopted:

[0050] A liquid crystal writing device comprises the above-mentioned writing film for increasing the local erasing voltage.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) Based on an embodiment of the present invention, when the electric field required to drive the cholesteric phase liquid crystal to flip is greater than the upper limit of the driving voltage that the driving chip can provide and cannot be normally erased, the method of increasing the erasing voltage of the liquid crystal writing device of the present invention can form a higher erasing electric field in a partial strip area of ​​the liquid crystal writing device while keeping the output voltage of the driving chip unchanged, thereby erasing the content of the partial strip area. Erasing a part of the strip area each time can further achieve the complete erasing of the entire liquid crystal writing device. Under the premise of not destroying the original structure of the liquid crystal writing device, the writing content of the strip area or the entire area on the liquid crystal writing device can be erased by increasing the local erasing voltage, thereby ensuring the normal use of the liquid crystal writing device and improving the service life of the product.

[0053] (2) Based on an embodiment of the present invention, when the electric field required to drive the cholesteric liquid crystal to flip is greater than the upper limit of the driving voltage that the driving chip can provide and cannot be erased normally, the method of increasing the erasing voltage of the liquid crystal writing device of the present invention can form a higher erasing electric field in the target erasing area of ​​the liquid crystal writing device while keeping the output voltage of the driving chip unchanged, thereby achieving local erasing of the target erasing area.

[0054] (3) Based on an implementation of the present invention, within the voltage limit of the driver chip, a higher voltage erasing effect is achieved by outputting a lower voltage, thereby reducing the requirements for the boost circuit and improving the power utilization efficiency.

[0055] (4) According to an embodiment of the present invention, by adjusting the magnitude of the voltage applied to different conductive regions, it is possible to form an erasing electric field as high as possible, or to achieve a local erasing effect as good as possible.

[0056] (5) Based on an embodiment of the present invention, by connecting an external capacitor to the first conductive layer or the second conductive layer and utilizing the method of the present invention for increasing the erasing voltage of a liquid crystal writing device, the electric field loaded between the first conductive layer and the second conductive layer can be increased, and the entire written content can be completely erased by utilizing a relatively low output voltage of the driving chip.

[0057] Other features and advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a schematic structural diagram of a liquid crystal writing device in an embodiment of the present invention;

[0059] Figure 2 This is a schematic diagram of dividing the conductive regions of the first conductive layer and the second conductive layer in the first embodiment of the present invention;

[0060] Figure 3 hereinafter is a process principle diagram of a method for increasing the erasing voltage of a liquid crystal writing device in Embodiment 1 of the present invention;

[0061] Figure 4 A schematic diagram of voltage loading variation of a method for increasing the erasing voltage of a liquid crystal writing device in Embodiment 3 of the present invention;

[0062] Figure 5 This is a process principle diagram of a method for increasing the erasing voltage of a liquid crystal writing device in Embodiment 3 of the present invention;

[0063] Figure 6 This is a process principle diagram of a method for increasing the erasing voltage of a liquid crystal writing device in Embodiment 6 of the present invention;

[0064] Figure 7 This is a process principle diagram of a method for increasing the erasing voltage of a liquid crystal writing device in Embodiment 7 of the present invention. DETAILED DESCRIPTION

[0065] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0066] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0067] Embodiment 1

[0068] In one or more embodiments, a method for increasing the erasing voltage of a liquid crystal writing device is disclosed, wherein, in combination with Figure 1 The liquid crystal writing device includes a first substrate layer, a first conductive layer, a cholesteric liquid crystal layer, a second conductive layer, a second substrate layer and a substrate arranged in sequence from top to bottom; the first substrate layer and the second substrate layer are usually made of PET film, and the first conductive layer and the second conductive layer are usually made of ITO film.

[0069] In this embodiment, in order to realize the local erasing function of the liquid crystal writing device, the first conductive layer and the second conductive layer are respectively divided into a plurality of parallel strip-shaped conductive regions, and the conductive regions on the first conductive layer and the conductive regions on the second conductive layer are perpendicular to each other in space. Figure 2 In this embodiment, the first conductive layer is divided into a plurality of mutually parallel and insulated vertical strip-shaped conductive regions, and the second conductive layer is divided into a plurality of mutually parallel and insulated horizontal strip-shaped conductive regions. Of course, the specific division method can be adjusted and interchanged as needed.

[0070] When the electric field required to drive the cholesteric liquid crystal to flip is greater than the upper limit of the driving voltage that the driving chip can provide, the method of increasing the erasing voltage of the liquid crystal writing device in this embodiment is as follows:

[0071] (1) Combination Figure 2 , a first voltage V1 is applied to all conductive areas on the first conductive layer, and a second voltage V2 is applied to all conductive areas on the second conductive layer; wherein, ;

[0072] If the second voltage is used as the reference zero potential, then:

[0073] ;

[0074] Among them, V st is the erasure start voltage of the cholesteric liquid crystal, and the erasure start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state.

[0075] At this time, the voltage difference between the two conductive layers is less than the erase start voltage V of the liquid crystal. st , it is impossible to erase the written content on the liquid crystal writing device.

[0076] (2) Control the drive outputs corresponding to all conductive areas on the first conductive layer to be in a high impedance state, and keep the conductive areas at set positions on the second conductive layer applying a second voltage. The first voltage V1 is applied to the remaining conductive area on the second conductive layer, so that the second voltage V2 is applied to the second conductive layer. The electric field at the corresponding position of the conductive area is increased to be greater than the erasure start voltage of the cholesteric liquid crystal, thereby erasing the written content at the corresponding position.

[0077] In this embodiment, after controlling the drive outputs corresponding to all conductive regions on the first conductive layer to be in a high impedance state, a first voltage V1 and a second voltage V2 are applied to the second conductive layer in a reasonable manner. The number of conductive regions enables a second voltage to be applied to the second conductive layer The electric field at the corresponding position of the conductive area is increased to be greater than the erasure start voltage of the cholesteric liquid crystal, thereby erasing the written content at the corresponding position.

[0078] The so-called high impedance state (Hiz) refers to controlling these conductive areas and their corresponding driving circuits to be in an 'open circuit' state, that is, they are physically connected but have no current input or current output.

[0079] As a specific example, Figure 2 The dotted line in the figure divides the first conductive layer into two parts, A1 and A2, and divides the second conductive layer into two parts, B1 and B2; after controlling the drive outputs corresponding to all conductive areas on the first conductive layer to be in a high impedance state, a first voltage can be applied to the B1 part on the second conductive layer , the B2 portion on the second conductive layer maintains a second voltage The content written at the corresponding position of the B2 part can be erased; in the next cycle, the first voltage is applied to the B2 part on the second conductive layer. , keep the second voltage applied to part B1 If the B1 portion is unchanged, the corresponding position of the B1 portion can be erased; in this way, all the contents on the entire liquid crystal writing device can be erased.

[0080] Figure 3 The specific process principle of realizing local erasure is given:

[0081] Reference Figure 3 , the upper and lower conductive layers of the entire liquid crystal writing device are equivalent to two equivalent capacitors C1 and C2; wherein, the equivalent capacitor C1 is formed by the A1 part of the first conductive layer and the B1 part of the second conductive layer; the equivalent capacitor C2 is formed by the A2 part of the first conductive layer and the B2 part of the second conductive layer; one electrode of the equivalent capacitors C1 and C2 are connected together because they belong to the same one or more conductive strips.

[0082] In this embodiment, the second voltage As the reference zero potential, .

[0083] First, a first voltage is applied to all conductive areas on the first conductive layer. , zero voltage is applied to all conductive areas on the second conductive layer, at this time: ;in, is the voltage across the equivalent capacitor C1, from top to bottom; is the voltage across the equivalent capacitor C2, from top to bottom. , so the written content on the LCD writing device cannot be erased.

[0084] Then, all the conductive areas on the first conductive layer are controlled to be in a high resistance state (Hiz), and all the conductive areas on the second conductive layer are still applied with zero voltage. At this time: ;in, is the voltage across the equivalent capacitor C1, from top to bottom; is the voltage across the equivalent capacitor C2, from top to bottom.

[0085] Next, a first voltage is applied to the conductive area of ​​the B1 portion on the second conductive layer. , the conductive area of ​​the B2 portion on the second conductive layer is still applied with zero voltage. At this time, the first voltage The voltage is divided by two equivalent capacitors C1 and C2, and the voltage on the equivalent capacitor C1 is: , the direction is from bottom to top; the voltage divided on the equivalent capacitor C2 is: , direction is from top to bottom.

[0086] Therefore, the voltage across the equivalent capacitor C1 is:

[0087] ;

[0088] The voltage across the equivalent capacitor C2 is:

[0089] ;

[0090] C1 and C2 are the capacitance values ​​of two equivalent capacitors. Generally, the ratio of the equivalent capacitances C1 and C2 can be equivalently calculated using the areas of their corresponding conductive regions.

[0091] It can be seen that at this time, the electric field loaded on the second conductive layer B2 is larger than the original Has improved .

[0092] If the size of the B1 part and the B2 part on the second conductive layer are the same, then:

[0093] C1=C2;

[0094] ;

[0095] The erasing electric field at the position corresponding to the B2 part can be increased to 1.5 times of the original value to achieve erasing of the position corresponding to the B2 part. When erasing next time, after the drive outputs corresponding to all the conductive areas on the first conductive layer are in a high impedance state (Hiz), a first voltage can be applied to the conductive area of ​​the B2 part on the second conductive layer. , the conductive area of ​​the B1 part on the second conductive layer is still applied with zero voltage, so that the corresponding position of the B1 part can be erased, thereby achieving erasure of the entire surface of the liquid crystal writing device.

[0096] It should be noted that after all the conductive regions on the first conductive layer are controlled to be in a high resistance state (Hiz), a first voltage may be applied to the conductive region of the B1 portion on the second conductive layer. , that is, the time interval between these two processes can be very short.

[0097] certainly, Figure 2 The position of the dotted line can be adjusted, or the B1 part or the B2 part on the second conductive layer can be a non-adjacent conductive area, and the first voltage is applied to certain conductive areas on the second conductive layer by controlling , then the electric field at the corresponding position of the remaining conductive area on the second conductive layer can be improved, as long as the equivalent capacitance is reasonably selected. and equivalent capacitance The magnitude relationship between them makes the electric field loaded on the remaining conductive area of ​​the conductive layer B satisfy: >V st , the corresponding position of the remaining conductive area of ​​the conductive layer B can be erased.

[0098] It can be understood that the voltages applied to the conductive layer A and the conductive layer B are interchanged according to the set time rules, so that the direction of the electric field loaded on the liquid crystal in the erased area is reversed, that is, the electric field at both ends of the liquid crystal corresponding to the erased area is flipped to prevent the liquid crystal from being passivated.

[0099] It should be noted that the state of the liquid crystal writing device before or after the method of increasing the erasing voltage of the liquid crystal writing device given in this embodiment is not specifically limited and can be set according to actual needs. For example, after an erasing process is completed, if you want to continue writing, you need to perform a discharge process.

[0100] The method of this embodiment can realize erasing of the band-shaped area on the liquid crystal writing device. By erasing different band-shaped areas one by one, the entire liquid crystal writing device can be erased.

[0101] In some embodiments, although the driving voltage generated by the driving chip can achieve local erasure, the driving voltage value required to be output by the driving chip is relatively large, which increases the power consumption of the product. By adopting the method of increasing the erasure voltage of the liquid crystal writing device of this embodiment, the driving chip can generate a lower driving voltage, which can meet the needs of local erasure, reduce power consumption, and increase the service life of the product.

[0102] In other embodiments, if the upper limit of the driving voltage generated by the driver chip is , and the erasure start voltage of cholesteric liquid crystal becomes greater than , it is impossible to erase the written content according to the conventional local erasing method; by adopting the method of increasing the erasing voltage of the liquid crystal writing device of this embodiment, a higher erasing electric field can be formed, and the written content can be erased without changing the hardware structure, thereby increasing the service life of the product.

[0103] Embodiment 2

[0104] In one or more embodiments, a method for increasing the erasing voltage of a liquid crystal writing device is disclosed. The implementation process and principle of the method in this embodiment are exactly the same as those in the first embodiment, and the only difference is that the voltage applied to the first conductive layer and the voltage applied to the second conductive layer are swapped, that is:

[0105] A first voltage V1 is applied to all conductive regions on the second conductive layer, and a second voltage V2 is applied to all conductive regions on the first conductive layer; wherein, , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0106] Controlling the drive outputs corresponding to all the conductive areas on the second conductive layer to be in a high impedance state;

[0107] By keeping the second voltage V2 applied to the conductive area at the set position on the first conductive layer unchanged and applying the first voltage V1 to the remaining conductive areas on the first conductive layer, the electric field at the corresponding position of the conductive area on the first conductive layer to which the second voltage V2 is applied can be increased to a level greater than the erasure start voltage of the cholesteric liquid crystal, thereby achieving erasure of the written content at the corresponding position.

[0108] Embodiment 3

[0109] In one or more embodiments, a method for increasing the erasing voltage of a liquid crystal writing device is disclosed, wherein the structure of the liquid crystal writing device is the same as that in the first embodiment and will not be described in detail.

[0110] The specific process of the method for increasing the erasing voltage of the liquid crystal writing device in this embodiment is as follows:

[0111] (1) Combination Figure 4 The shaded parts on the two conductive layers are the positions corresponding to the target erasing areas; a first voltage is applied to the conductive area covered by the target erasing area on the first conductive layer. , applying voltage to other conductive areas on the first conductive layer ; Apply a second voltage to all conductive areas on the second conductive layer ;in, , , V stis an erasure start voltage of cholesteric liquid crystal, and the erasure start voltage is a voltage that can cause part of liquid crystal molecules to start changing from a planar state to a focal conic state.

[0112] At this time, the voltage difference at any position between the two conductive layers is less than the erase start voltage V of the liquid crystal. st , it is impossible to erase the written content on the liquid crystal writing device.

[0113] (2) controlling the drive output corresponding to the conductive area covered by the target erasing area on the first conductive layer to be in a high impedance state; applying a third voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, and the electric field in other areas outside the target erasing area is less than the erasing start voltage of the cholesteric liquid crystal, thereby erasing the written content in the target erasing area while the written content in other areas remains unchanged.

[0114] The above process also satisfies:

[0115] ;

[0116] ;

[0117] ;

[0118] ;

[0119] Among them, C4 is the equivalent capacitance between the upper and lower conductive layers at the coverage position of the target erase area, that is, Figure 4 C3 is the equivalent capacitance between the other regions (E2 and E3) except the target erasing region E1 in the conductive region E covered by the target erasing region on the first conductive layer and the corresponding regions on the second conductive layer, and are all constants not less than 0.

[0120] is the electric field corresponding to the target erasing area, and , and It is the electric field corresponding to other areas outside the target erasing area.

[0121] At this time, only the electric field corresponding to the target erasing area is greater than the erasing start voltage of the cholesteric liquid crystal, while the electric fields of other non-erasing areas are less than the erasing start voltage of the cholesteric liquid crystal, so that the target erasing area can be erased.

[0122] Figure 5 The specific process principle of realizing local erasure is given:

[0123] Reference Figure 5 , the upper and lower conductive layers of the liquid crystal writing device are equivalent to two equivalent capacitors C3 and C4; for the convenience of description, the second voltage As the reference zero potential, .

[0124] In this embodiment, the second voltage As a reference zero potential, a first voltage is first applied to the conductive area covered by the target erasing area on the first conductive layer. , applying voltage to other conductive areas on the first conductive layer ; Apply zero voltage to all conductive areas on the second conductive layer; At this time: ;in, is the voltage across the equivalent capacitor C3, from top to bottom; is the voltage across the equivalent capacitor C4, from top to bottom. The voltage difference between the other conductive areas on the first conductive layer except the conductive area E and the second conductive layer is .because and Both are lower than the erase start voltage of the liquid crystal , so the written content on the LCD writing device cannot be erased.

[0125] Then, the driving output corresponding to the conductive area E covered by the target erasing area on the first conductive layer is controlled to be in a high impedance state, and all the conductive areas on the second conductive layer are still applied with zero voltage. ,in, is the voltage across the equivalent capacitor C3, from top to bottom; is the voltage across the equivalent capacitor C4, from top to bottom.

[0126] Next, a third voltage is applied to the conductive area F covered by the target erasing area on the second conductive layer. , applying voltage to other conductive areas on the second conductive layer ( ), at this time, the voltage The voltage is divided by two equivalent capacitors C3 and C4, and the voltage on the equivalent capacitor C3 is: , the direction is from bottom to top; the voltage divided on the equivalent capacitor C4 is: , direction is from top to bottom.

[0127] It should be noted that the third voltage in this embodiment The second voltage can be The same value can also be taken at the second voltage Values ​​that vary slightly around the value.

[0128] After controlling the driving output corresponding to the conductive area E covered by the target erasing area on the first conductive layer to be in a high impedance state, a third voltage may be applied to the conductive area F covered by the target erasing area on the second conductive layer. , applying voltage to other conductive areas on the second conductive layer ( ), that is, the time interval between these two processes can be very short.

[0129] Therefore, the voltage across the equivalent capacitor C3 is:

[0130] ;

[0131] The voltage across the equivalent capacitor C4 is:

[0132] ;

[0133] C3 and C4 are capacitance values ​​of two equivalent capacitors. Generally, the ratio of the equivalent capacitances C3 and C4 can be equivalently calculated using the areas of their corresponding conductive regions.

[0134] That is, the voltage applied to the target erase area is changed from the original Increase to , greater than the erase start voltage of the liquid crystal , the target erasing area can be erased. The voltage difference between the conductive area E of the first conductive layer, except for the shaded area, and the second conductive layer is , which is less than the erase start voltage of the liquid crystal In addition, the voltage differences between the other conductive areas on the first conductive layer except the conductive area E and the second conductive layer are respectively and , are also smaller than the erase start voltage of the liquid crystal Therefore, the written content in other areas outside the target erasing area cannot be erased, achieving the effect of partial erasing.

[0135] As an optional implementation, the values ​​of a and b in the above voltage may be selected as follows:

[0136] a∈[0,1]; b=1;

[0137] At this time, the voltage loaded on the target erasing area can be increased as much as possible, that is, the voltage of the target erasing area can be increased higher to achieve a better voltage increase effect.

[0138] As another optional implementation, the values ​​of a and b in the above voltage may also be selected as follows:

[0139] a∈[0.5, 2.2]; b∈[2a-0.5, 2a+0.5];

[0140] At this time, the electric field in the target erasing area can be made greater than the electric field in the surrounding non-erasing area, thereby achieving a better local erasing effect.

[0141] As a more specific embodiment, the values ​​of a and b further satisfy:

[0142] a∈[0.8,0.9]; b∈[1.6,1.8];

[0143] At this time, the electric field of the target erasing area can be made as large as possible as compared to the electric field of the surrounding non-erasing area, thereby achieving a better local erasing effect.

[0144] It can be understood that the voltages applied to the first conductive layer and the second conductive layer are interchanged according to the set time rules, so that the direction of the electric field loaded on the liquid crystal in the erased area is reversed, that is, the electric field at both ends of the liquid crystal corresponding to the erased area is flipped to prevent the liquid crystal from being passivated.

[0145] It should be noted that the state of the liquid crystal writing device before or after the method of increasing the erasing voltage of the liquid crystal writing device given in this embodiment is not specifically limited and can be set according to actual needs. For example, after an erasing process is completed, if you want to continue writing, you need to perform a discharge process.

[0146] The method of this embodiment can realize partial erasure of the target erasure area.

[0147] In some embodiments, although the driving voltage generated by the driving chip can achieve local erasure, the driving voltage value required to be output by the driving chip is relatively large, which increases the power consumption of the product. By adopting the method of increasing the erasure voltage of the liquid crystal writing device of this embodiment, the driving chip can generate a lower driving voltage, which can meet the needs of local erasure, reduce power consumption, and increase the service life of the product.

[0148] In other embodiments, if the upper limit of the driving voltage generated by the driver chip is , and the erasure start voltage of cholesteric liquid crystal becomes greater than , it is impossible to erase the written content according to the conventional local erasing method; by adopting the method of increasing the erasing voltage of the liquid crystal writing device of this embodiment, a higher erasing electric field can be formed, and local erasing of the written content can be achieved without changing the hardware structure, thereby improving the service life of the product.

[0149] Embodiment 4

[0150] In one or more embodiments, a method for increasing the erasing voltage of a liquid crystal writing device is disclosed. The implementation process and principle of the method in this embodiment are exactly the same as those of the method in Embodiment 3, except that the voltage applied to the first conductive layer and the voltage applied to the second conductive layer are swapped, that is:

[0151] Applying a first voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ; Apply a second voltage to all conductive areas on the first conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0152] Control the drive output corresponding to the conductive area covered by the target erasing area on the second conductive layer to be in a high impedance state, and apply a third voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer , which can increase the electric field in the target erasing area to a level greater than the erasing start voltage of the cholesteric liquid crystal, and the electric field in other areas outside the target erasing area is less than the erasing start voltage of the cholesteric liquid crystal, thereby erasing the written content in the target erasing area while keeping the written content in other areas unchanged.

[0153] The above process also satisfies:

[0154] ;

[0155] ;

[0156] ;

[0157] ;

[0158] Wherein, C4 is the equivalent capacitance between the upper and lower conductive layers at the position covered by the target erasing area; C3 is the equivalent capacitance between other areas of the conductive area E covered by the target erasing area on the first conductive layer, except the target erasing area E1, and the corresponding part on the second conductive layer, and are all constants not less than 0.

[0159] is the electric field corresponding to the target erasing area, and , and It is the electric field corresponding to other areas outside the target erasing area.

[0160] At this time, only the electric field corresponding to the target erasing area is greater than the erasing start voltage of the cholesteric liquid crystal, while the electric fields of other non-erasing areas are less than the erasing start voltage of the cholesteric liquid crystal, so that the target erasing area can be erased.

[0161] In the above-mentioned first to fourth embodiments, the voltages applied to the respective conductive regions on the two conductive layers can be provided by a driving circuit or a driving chip.

[0162] Embodiment 5

[0163] In one or more embodiments, a writing film for increasing a local erase voltage is disclosed, comprising a first conductive layer, a cholesteric liquid crystal layer, and a second conductive layer sequentially arranged from top to bottom, wherein the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually insulated conductive regions, and further comprising:

[0164] The control unit is configured to use the method of increasing the erasing voltage of the liquid crystal writing device described in any one of Embodiments 1 to 4 to achieve erasing of the target erasing area.

[0165] The liquid crystal writing film of this embodiment can be applied to liquid crystal products such as blackboards, drawing boards and writing boards to increase the service life of the products.

[0166] Embodiment 6

[0167] In one or more embodiments, a method for increasing the erasing voltage of a liquid crystal writing device is disclosed. The liquid crystal writing device of this embodiment includes a first substrate layer, a first conductive layer, a cholesteric liquid crystal layer, a second conductive layer, a second substrate layer and a substrate arranged in sequence from top to bottom; the first substrate layer and the second substrate layer are usually made of PET film, and the first conductive layer and the second conductive layer are usually made of ITO film. Different from the first embodiment, the first conductive layer and the second conductive layer of this embodiment are not divided, and the driving voltage is directly loaded on the entire first conductive layer and the second conductive layer. By using the voltage difference between the two conductive layers, all written contents can be erased with one key.

[0168] In addition, in order to increase the erasing voltage of the liquid crystal writing device, the fifth capacitor C5 is externally connected to the first conductive layer in this embodiment; the method of this embodiment specifically includes the following process:

[0169] Applying a fourth voltage to the first conductive layer , a fifth voltage is applied to the second conductive layer , a fifth voltage is applied to the end of the fifth capacitor C5 away from the first conductive layer , ; V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0170] Control the corresponding drive output on the first conductive layer to be in a high impedance state, keep the voltage applied to the second conductive layer unchanged; apply a fourth voltage to the end of the fifth capacitor C5 away from the first conductive layer ; It is possible to increase the electric field loaded between the first conductive layer and the second conductive layer to a level greater than the erasure start voltage of the cholesteric liquid crystal , thereby erasing all written content on the liquid crystal writing device.

[0171] It should be noted that in order to achieve a better voltage boost effect, it is assumed that the equivalent capacitance between the first conductive layer and the second conductive layer is C m , then the fifth capacitor C5 must be much larger than C m , as a specific example, C5 ≥ 10C m .

[0172] Combine the following Figure 6 The principle of the method of this embodiment is described in detail. For convenience, this embodiment uses the fifth voltage As the reference zero potential, .

[0173] First, a fourth voltage is applied to the first conductive layer. , zero voltage is applied to the second conductive layer; one end of the fifth capacitor C5 is connected to the first conductive layer, and zero voltage is applied to the other end. At this time, the voltage difference between the first conductive layer and the second conductive layer is , the direction is from top to bottom, and Therefore, the writing content on the writing device will not be erased; the voltage difference across the fifth capacitor C5 is , the direction is from top to bottom.

[0174] Then, the corresponding driving output on the first conductive layer is controlled to be in a high impedance state. At this time, the voltage difference between the two conductive layers and between the fifth capacitor C5 is still .

[0175] Finally, keep the zero voltage applied to the second conductive layer unchanged; apply a fourth voltage to the end of the fifth capacitor C5 away from the first conductive layer. ; At this time, the fourth voltage By two capacitors C m and C5 voltage divider, capacitor C m The voltage obtained from the above is: , direction is from top to bottom; the voltage divided on the first capacitor C5 is , direction is from bottom to top.

[0176] At this point, the voltage across the first capacitor C5 becomes: ;

[0177] The voltage difference between the first conductive layer and the second conductive layer is: .

[0178] It can be seen that the electric field loaded between the first conductive layer and the second conductive layer is larger than the driving output voltage Improved By properly setting the size of the first capacitor C5, , which can completely erase the written content on the liquid crystal writing device.

[0179] It should be noted that after controlling the corresponding driving output on the first conductive layer to be in a high impedance state, a fourth voltage may be applied to the end of the fifth capacitor C5 away from the first conductive layer. ; That is, the interval between these two processes can be very short.

[0180] As an optional implementation, a sixth capacitor C6 may be externally connected to the second conductive layer. When the fifth capacitor is used to increase the erase voltage, the drive output corresponding to the end of the sixth capacitor away from the second conductive layer is controlled to be always in a high-impedance state. When the sixth capacitor C6 is used to increase the erase voltage, refer to the method of Example 7, and control the drive output corresponding to the end of the fifth capacitor C5 away from the first conductive layer to always be in a high-impedance state.

[0181] It should be noted that the voltages loaded on the first conductive layer, the second conductive layer, the end of the fifth capacitor C5 away from the first conductive layer, and the end of the sixth capacitor C6 away from the second conductive layer can all be provided by a driving circuit or a driving chip.

[0182] Embodiment 7

[0183] In one or more embodiments, a method for increasing the erasing voltage of a liquid crystal writing device is disclosed. The liquid crystal writing device of this embodiment includes a first substrate layer, a first conductive layer, a cholesteric liquid crystal layer, a second conductive layer, a second substrate layer and a substrate arranged in sequence from top to bottom; the first substrate layer and the second substrate layer are usually made of PET film, and the first conductive layer and the second conductive layer are usually made of ITO film. Different from the first embodiment, the first conductive layer and the second conductive layer of this embodiment are not divided, and the driving voltage is directly loaded on the entire first conductive layer and the second conductive layer. By using the voltage difference between the two conductive layers, all written contents can be erased with one key.

[0184] In addition, in order to increase the erasing voltage of the liquid crystal writing device, the seventh capacitor C7 is externally connected to the second conductive layer in this embodiment; the method of this embodiment specifically includes the following process:

[0185] Applying a fourth voltage to the second conductive layer , a fifth voltage is applied to the first conductive layer , a fifth voltage is applied to the end of the seventh capacitor C7 away from the second conductive layer , ; V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state;

[0186] Control the corresponding drive output on the second conductive layer to be in a high impedance state; keep the voltage applied to the first conductive layer unchanged; apply a fourth voltage to the end of the seventh capacitor away from the second conductive layer ; It is possible to increase the electric field loaded between the first conductive layer and the second conductive layer to a level greater than the erasure start voltage of the cholesteric liquid crystal , thereby erasing all written content on the liquid crystal writing device.

[0187] It should be noted that in order to achieve a better voltage boost effect, it is assumed that the equivalent capacitance between the first conductive layer and the second conductive layer is C m , then the seventh capacitor C7 must be much larger than C m , as a specific example, C7 ≥ 10C m .

[0188] Combine the following Figure 7 The principle of the method of this embodiment is described in detail. For convenience, this embodiment uses the fifth voltage As the reference zero potential, .

[0189] First, a fourth voltage is applied to the second conductive layer , zero voltage is applied to the first conductive layer; one end of the seventh capacitor C7 is connected to the second conductive layer, and zero voltage is applied to the other end. At this time, the voltage difference between the first conductive layer and the second conductive layer is , the direction is from bottom to top, and Therefore, the writing content on the writing device will not be erased; the voltage difference across the seventh capacitor C7 is , direction is from bottom to top.

[0190] Then, the corresponding driving output on the second conductive layer is controlled to be in a high impedance state. At this time, the voltage difference between the two conductive layers and between the seventh capacitor C7 is still .

[0191] Next, the zero voltage applied to the first conductive layer is kept unchanged; a fourth voltage is applied to the end of the seventh capacitor C7 away from the second conductive layer. At this time, the fourth voltage By two capacitors C m and C7 voltage divider, capacitor C m The voltage obtained from the above is: , the direction is from bottom to top; the voltage divided on the seventh capacitor C7 is , direction is from top to bottom.

[0192] At this point, the voltage across the seventh capacitor C7 becomes: ;

[0193] The voltage difference between the first conductive layer and the second conductive layer is: .

[0194] It can be seen that the electric field loaded between the first conductive layer and the second conductive layer is larger than the driving output voltage Improved By properly setting the size of the seventh capacitor C7, , which can completely erase the written content on the liquid crystal writing device.

[0195] Similarly, after controlling the corresponding driving output on the second conductive layer to be in a high impedance state, a fourth voltage may be applied to the end of the seventh capacitor C7 away from the second conductive layer. ; That is, the interval between these two processes can be very short.

[0196] As an optional implementation, an eighth capacitor C8 may be externally connected to the first conductive layer. When the seventh capacitor C7 is used to increase the erase voltage, the drive output corresponding to the end of the eighth capacitor C8 away from the first conductive layer is controlled to be always in a high-impedance state. When the eighth capacitor C8 is used to increase the erase voltage, refer to the method of Example 6, and control the drive output corresponding to the end of the seventh capacitor C7 away from the second conductive layer to be always in a high-impedance state.

[0197] It should be noted that the voltages loaded on the first conductive layer, the second conductive layer, the end of the seventh capacitor C7 away from the second conductive layer, and the end of the eighth capacitor C8 away from the first conductive layer can all be provided by a driving circuit or a driving chip.

[0198] Embodiment 8

[0199] In one or more embodiments, a writing film for increasing a local erase voltage is disclosed, comprising a first conductive layer, a cholesteric liquid crystal layer, and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are not divided, and further comprising:

[0200] The control unit is configured to use the method of increasing the erasing voltage of the liquid crystal writing device described in any one of the sixth embodiment or the seventh embodiment to achieve complete erasure of the written content on the writing device.

[0201] The liquid crystal writing film of this embodiment can be applied to liquid crystal products such as blackboards, drawing boards and writing boards to increase the service life of the products.

[0202] Embodiment 9

[0203] In one or more embodiments, a liquid crystal writing device is disclosed, comprising the writing film for increasing the local erasing voltage as described in the fifth or eighth embodiment.

[0204] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for increasing the erasing voltage of a liquid crystal writing device, wherein the liquid crystal writing device comprises a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually insulated strip-shaped conductive regions, wherein the method include: A first voltage V1 is applied to all conductive regions on the first conductive layer, and a second voltage V2 is applied to all conductive regions on the second conductive layer; wherein, , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Control the drive outputs corresponding to all conductive areas on the first conductive layer to be in a high impedance state; keep the conductive areas at set positions on the second conductive layer applying a second voltage The first voltage V1 is applied to the remaining conductive area on the second conductive layer, so that the second voltage V2 is applied to the second conductive layer. The electric field at the corresponding position of the conductive area is increased to be greater than the erasure start voltage of the cholesteric liquid crystal, thereby erasing the written content at the corresponding position.

2. A method for increasing the erasing voltage of a liquid crystal writing device, wherein the liquid crystal writing device comprises a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually insulated strip-shaped conductive regions, wherein the method include: A first voltage V1 is applied to all conductive regions on the second conductive layer, and a second voltage V2 is applied to all conductive regions on the first conductive layer; wherein, , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Control the drive outputs corresponding to all the conductive areas on the second conductive layer to be in a high-impedance state; keep the second voltage V2 applied to the conductive area at the set position on the first conductive layer unchanged, and apply the first voltage V1 to the remaining conductive areas on the first conductive layer, so that the electric field at the corresponding position of the conductive area on the first conductive layer to which the second voltage V2 is applied can be increased to a level greater than the erase start voltage of the cholesteric liquid crystal, thereby achieving erasure of the written content at the corresponding position.

3. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 1 or 2, characterized in that: Taking the second voltage V2 as the reference zero potential, the following conditions are satisfied: 。 4. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 1 or 2, characterized in that: The written contents at some positions are erased each time, thereby completely erasing all positions on the liquid crystal writing device.

5. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 1 or 2, characterized in that: The voltages applied to the first conductive layer and the second conductive layer are interchanged according to a set time rule to prevent the liquid crystal from being passivated.

6. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 1 or 2, characterized in that: The first conductive layer and the second conductive layer are respectively divided into a plurality of mutually parallel strip-shaped conductive regions, and the strip-shaped conductive regions on the first conductive layer and the strip-shaped conductive regions on the second conductive layer are spatially perpendicular to each other.

7. A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, characterized in that the method include: Applying a first voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer ; Applying a second voltage to all conductive areas on the second conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Control the drive output corresponding to the conductive area covered by the target erasing area on the first conductive layer to be in a high impedance state; apply a third voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, while the electric field in other areas is less than the erasing start voltage of the cholesteric liquid crystal; thereby erasing the written content in the target erasing area, while the written content in other areas remains unchanged; wherein, and is a constant not less than 0; the values ​​of a and b satisfy: a∈[0,1]; b=1; The third voltage With the second voltage Same or different.

8. A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, characterized in that the method include: Applying a first voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ; Apply a second voltage to all conductive areas on the first conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Control the drive output corresponding to the conductive area covered by the target erasing area on the second conductive layer to be in a high impedance state; apply a third voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, while the electric field in other areas is less than the erasing start voltage of the cholesteric liquid crystal; thereby erasing the written content in the target erasing area, while the written content in other areas remains unchanged; wherein, and is a constant not less than 0; the values ​​of a and b satisfy: a∈[0,1]; b=1; the third voltage With the second voltage Same or different.

9. A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, characterized in that the method include: Applying a first voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer ; Apply a second voltage to all conductive areas on the second conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Control the drive output corresponding to the conductive area covered by the target erasing area on the first conductive layer to be in a high impedance state; apply a third voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, while the electric field in other areas is less than the erasing start voltage of the cholesteric liquid crystal; thereby erasing the written content in the target erasing area, while the written content in other areas remains unchanged; wherein, and is a constant not less than 0; the values ​​of a and b satisfy: a∈[0.5, 2.2]; b∈[2a-0.5, 2a+0.5]; the third voltage With the second voltage Same or different.

10. A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being respectively divided into a plurality of mutually insulated strip-shaped conductive regions, characterized in that the method include: Applying a first voltage to the conductive area covered by the target erasing area on the second conductive layer , applying voltage to other conductive areas on the second conductive layer ; Apply a second voltage to all conductive areas on the first conductive layer ;in, , , V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Control the drive output corresponding to the conductive area covered by the target erasing area on the second conductive layer to be in a high impedance state; apply a third voltage to the conductive area covered by the target erasing area on the first conductive layer , applying voltage to other conductive areas on the first conductive layer ( ), the electric field in the target erasing area can be increased to a level greater than the erasing start voltage of the cholesteric liquid crystal, while the electric field in other areas is less than the erasing start voltage of the cholesteric liquid crystal; thereby erasing the written content in the target erasing area, while the written content in other areas remains unchanged; wherein, and is a constant not less than 0; the values ​​of a and b satisfy: a∈[0.5, 2.2]; b∈[2a-0.5, 2a+0.5]; the third voltage With the second voltage Same or different.

11. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in any one of claims 9 or 10, characterized in that: The values ​​of a and b further satisfy: a∈[0.8,0.9];b∈[1.6,1.8].

12. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in any one of claims 7 to 10, characterized in that: The voltages applied to the first conductive layer and the second conductive layer are interchanged according to a set time rule to prevent the liquid crystal from being passivated.

13. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in any one of claims 7 to 10, characterized in that: The first conductive layer and the second conductive layer are respectively divided into a plurality of mutually parallel strip-shaped conductive regions, and the strip-shaped conductive regions on the first conductive layer and the strip-shaped conductive regions on the second conductive layer are spatially perpendicular to each other.

14. A writing film for increasing local erasing voltage, comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are respectively divided into a plurality of mutually insulated conductive regions, characterized in that: Also includes: The control unit is configured to use the method for increasing the erasing voltage of a liquid crystal writing device as described in any one of claims 1 to 13 to achieve erasing of a target erasing area.

15. A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being not divided, characterized in that: A fifth capacitor is externally connected to the first conductive layer; a fourth voltage is applied to the first conductive layer , a fifth voltage is applied to the second conductive layer , a fifth voltage is applied to the end of the fifth capacitor away from the first conductive layer , ; V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Controlling the corresponding driving output on the first conductive layer to be in a high impedance state; maintaining the voltage applied to the second conductive layer unchanged; Apply a fourth voltage to the end of the fifth capacitor away from the first conductive layer ; It is possible to increase the electric field loaded between the first conductive layer and the second conductive layer to a level greater than the erasure start voltage of the cholesteric liquid crystal , thereby erasing all written content on the liquid crystal writing device.

16. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 15, characterized in that: Also includes: A sixth capacitor is externally connected to the second conductive layer; and a driving output corresponding to a terminal of the sixth capacitor away from the second conductive layer is controlled to always be in a high impedance state.

17. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 15, characterized in that: The capacitance C between the first conductive layer and the second conductive layer m The fifth capacitor C5 satisfies the following relationship: C5 ≥ 10C m .

18. A method for increasing the erasing voltage of a liquid crystal writing device, the liquid crystal writing device comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, the first conductive layer and the second conductive layer being not divided, characterized in that: A seventh capacitor is externally connected to the second conductive layer; Applying a fourth voltage to the second conductive layer , a fifth voltage is applied to the first conductive layer , a fifth voltage is applied to the end of the seventh capacitor away from the second conductive layer , ; V st is an erase start voltage of cholesteric liquid crystal, and the erase start voltage is a voltage that can cause some liquid crystal molecules to start changing from a planar state to a focal conic state; Controlling the corresponding driving output on the second conductive layer to be in a high impedance state; Keep the voltage applied to the first conductive layer unchanged; apply a fourth voltage to the end of the seventh capacitor away from the second conductive layer ; It is possible to increase the electric field loaded between the first conductive layer and the second conductive layer to a level greater than the erasure start voltage of the cholesteric liquid crystal , thereby erasing all written content on the liquid crystal writing device.

19. A method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 18, characterized in that: Also includes: An eighth capacitor is externally connected to the first conductive layer; and a driving output corresponding to a terminal of the eighth capacitor away from the first conductive layer is controlled to always be in a high-impedance state.

20. The method for increasing the erasing voltage of a liquid crystal writing device as claimed in claim 18, characterized in that: The capacitance C between the first conductive layer and the second conductive layer m The following relationship is satisfied between the seventh capacitor C7: C7 ≥ 10C m .

21. A writing film for increasing local erasing voltage, comprising a first conductive layer, a cholesteric liquid crystal layer and a second conductive layer arranged in sequence from top to bottom, wherein the first conductive layer and the second conductive layer are not divided, characterized in that: Also includes: The control unit is configured to use the method of increasing the erasing voltage of the liquid crystal writing device as described in any one of claims 15 to 20 to achieve erasing of the written content.

22. A liquid crystal writing device, characterized in that: A writing film with increased local erasing voltage as claimed in claim 14 or 21.

Images