Electric field response liquid crystal chiral additive composition and liquid crystal composition

Abstract

The invention discloses an electric field response liquid crystal chiral additive composition which comprises a component A and a component B, wherein the component A contains a chiral molecular compound for inducing liquid crystal to generate spiral torsion; the component B is a compound for adjusting the spiral pitch of liquid crystal molecules; wherein hydrogen bonds can be formed between molecules of the component A and molecules of the component B. When the liquid crystal chiral additive composition responding to the electric field is added into liquid crystal, the screw pitch of the liquid crystal can change along with the change of external voltage. The liquid crystal pitch is changed by applying an electric field, so that the color of liquid crystal writing is changed, and particularly the color of new writing is influenced. According to the electric field response liquid crystal chiral additive composition, the obtained liquid crystal composition and the obtained liquid crystal blackboard, text content and mark content can be distinguished by writing different colors through voltage control, key points are highlighted, and the electric field response liquid crystal chiral additive composition and the liquid crystal composition and the obtained liquid crystal blackboard have important significance for improving classroom teaching quality.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal blackboards, and more particularly to an electric field-responsive liquid crystal chiral additive composition and a liquid crystal composition. Background Technology

[0002] With the rapid development of educational technology and the continuous innovation of teaching methods and equipment, LCD blackboards, as a new type of educational technology equipment, are becoming increasingly popular in classroom education due to their advantages such as environmental friendliness, energy saving, and reusability. They not only replace traditional blackboards, reducing dust pollution, but also integrate with modern information technology to achieve diversified display of teaching content and interactive teaching, greatly improving teaching efficiency and quality.

[0003] However, traditional LCD blackboards often use a black background with green or red text display mode. While this color scheme can meet basic writing and display needs to a certain extent, due to the characteristics of the LCD material itself, the color of the written text can only be preset after the LCD is filled into the LCD cell, and cannot be flexibly adjusted according to actual needs. In classroom teaching, teachers often need to use different writing colors to distinguish between text and markings, highlight key points, and enhance the intuitiveness and organization of teaching. However, existing LCD blackboards, due to their fixed writing colors, cannot meet the diverse writing needs of teachers, thus limiting their effectiveness in teaching to some extent. Summary of the Invention

[0004] To address the above technical problems, the present invention first provides an electric field-responsive liquid crystal chiral additive composition and a liquid crystal composition.

[0005] The electric field-responsive liquid crystal chiral additive composition comprises: Component A and component B; Component A is a chiral molecular compound that induces the helical twisting of liquid crystals; component B is used to form hydrogen bonds with component A, and the hydrogen bonds between component A and component B can be broken by an external electric field.

[0006] Through the bonding and breaking of hydrogen bonds, components A and B work together to adjust the pitch. The combination of components A and B exerts different helical twisting forces on the liquid crystal molecules through these bonding and breaking processes, thus causing the liquid crystal to exhibit different colors.

[0007] In this invention, the molecules of component A and component B are capable of forming hydrogen bonds, meaning that each molecule of component A and component B respectively includes at least one hydrogen bond donor and / or hydrogen bond acceptor, and the hydrogen bond donor and hydrogen bond acceptor cooperate with each other to form hydrogen bonds. That is, the molecule of component A includes at least one hydrogen bond donor and / or hydrogen bond acceptor, and component B contains a hydrogen bond acceptor and / or hydrogen bond donor that cooperates with component A.

[0008] In this invention, the formation of hydrogen bonds, as understood by those skilled in the art, means that hydrogen bonds are formed between component A and component B under normal temperature and pressure, and without the influence of a significant external electric or magnetic field.

[0009] In this invention, the mutual cooperation refers to the cooperation between hydrogen bond donors and hydrogen bond acceptors.

[0010] In this invention, the hydrogen bond acceptor is selected from: carbonyl ( ), nitro (-NO2), pyridyl ( ), fluorine (-F) groups.

[0011] In this invention, the hydrogen bond donor is selected from groups of hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), imino (-NH-), and mercapto (-SH).

[0012] The statement that the molecules of component A and component B each include at least one hydrogen bond donor and / or hydrogen bond acceptor means that the molecules of component A and component B each contain at least one of the aforementioned groups.

[0013] In an embodiment of the present invention, the molecule of component A contains a hydrogen bond acceptor, and the molecule of component B contains a hydrogen bond donor.

[0014] In this invention, the electric field response refers to the ability to adjust the breaking of hydrogen bonds between component A and component B by applying an external electric field.

[0015] In particular, when components A and B are used as chiral additives, their molecules induce helical twisting of the liquid crystal molecules. During this process, interactions occur between the chiral additive molecules and the liquid crystal molecules. This interaction, to some extent, restricts the position of the chiral additive molecules due to the ordered structure of the liquid crystal molecules. Therefore, under an electric field, compared to the disordered hydrogen bonds in the free state, the chiral liquid crystal additive of this invention can better respond to changes in the electric field to break the hydrogen bonds. This achieves pitch adjustment in response to the electric field.

[0016] Specifically, in liquid crystal compositions containing the chiral additives of this invention, the hydrogen bond structure of the chiral additives can be adjusted by regulating the applied electric field (voltage). The hydrogen bond structure includes the breaking and forming of hydrogen bonds between component A and component B.

[0017] Applying an external electric field can induce hydrogen bond breakage. This invention reveals that, based on the electric field-responsive chiral liquid crystal additive composition described herein, the liquid crystal pitch changes with the applied voltage. In the electric field-responsive chiral liquid crystal additive composition of this invention, components A and B exhibit hydrogen bond formation. In this form, component B is connected to component A via hydrogen bonds, and components A and B, as a whole, influence the pitch of the liquid crystal molecules. On the other hand, when an external electric field is applied, the applied electric field affects the hydrogen bonds, at least partially disrupting the original ordered structure formed by hydrogen bonds, resulting in hydrogen bond breakage. Due to the rapid hydrogen bond breakage, the amount of component A without component B in the composition increases, and the system tends to have component A alone influence the pitch of the liquid crystal molecules.

[0018] Specifically, the pitch of liquid crystal molecules can be changed by applying an electric field. Liquid crystal molecules with different pitches reflect light of different wavelengths when forming a planar state (P-state). In the process of writing with liquid crystals, applying an electric field causes a change in the pitch of the liquid crystal, thereby changing the color of the written text, especially affecting the color of newly written text.

[0019] The color of the newly written text here refers to the color of the text written under different applied electric fields, compared to the existing text on the blackboard. It should be noted that the applied electric field (or voltage) can be 0. This is to illustrate how different electric fields affect the pitch of liquid crystal molecules.

[0020] In this invention, component A is a chiral molecular compound that induces helical twisting of liquid crystal molecules.

[0021] Specifically, component A may optionally be a chiral additive with a high HTP value. Preferably, the absolute value of HTP of component A should be not less than 20 (μm). -1 In a preferred embodiment, the absolute value of HTP of component A should be not less than 25 (μm). -1 Preferably, it is not less than 40 (μm) -1 More preferably, it should be not less than 70 (μm) -1 ).

[0022] In this invention, component A is selected from chiral additives with isosorbide skeleton, chiral additives with binaphthol skeleton, and chiral additives with 2,2'-substituted biphenyl skeleton.

[0023] In this patent, the skeleton refers to the molecular structure in the chiral additive molecule that acts as an active center to induce the torsion of liquid crystal molecules.

[0024] In this invention, the framework refers to a molecular structure having the stated molecular structure, and based on the framework, other atoms or substituents are attached to the framework molecule as side groups or substituents. The framework serves as an active center for inducing helical torsion of the liquid crystal.

[0025] More specifically, taking a chiral additive whose component A is selected from the isosorbide backbone as an example. Furthermore, both component A and component B must satisfy the requirement that their molecules each include at least one hydrogen bond donor and / or hydrogen bond acceptor. When component A provides a hydrogen bond acceptor, component A may optionally have the following structure: Compound A1; Compound A2; The compounds A1 and A2 mentioned above are exemplary specific compounds that can be selected from component A.

[0026] Those skilled in the art can further modify the molecule according to the actual situation, for example, by making it a substituted compound A1 or a substituted compound A2. More specifically, for example, a fluorine (-F) substitution may be further included on the pyridine ring of the isonicotinic acid substituent in compound A1 or A2; or a fluorine (-F) substitution may be further included on the benzene ring of the p-hydroxybenzoic acid substituent in compound A2.

[0027] For those skilled in the art, component A can be obtained commercially or through conventional experimental methods. Taking compound A1 as an example, it can be obtained by reacting isosorbide with isonicotinic acid via a conventional esterification reaction. Similarly, for compound A2, a stepwise feeding method is used: step 1: esterification reaction of isosorbide with p-hydroxybenzoic acid; step 2: further esterification reaction of the esterification product from the previous step with isonicotinic acid to obtain compound A2. Those skilled in the art can also obtain variations of compound A2; for example, in step 2, replacing or partially replacing p-hydroxybenzoic acid with m-hydroxybenzoic acid and / or salicylic acid will also yield component A of the present invention.

[0028] For example, see the following reaction formula for compound A1.

[0029]

[0030] In this invention, component B is a compound that adjusts the helical pitch of liquid crystal molecules.

[0031] In this invention, component A and component B should each have at least one hydrogen bond donor or hydrogen bond acceptor, and component A and component B should cooperate to form hydrogen bonds.

[0032] In this invention, the molecule of component B is an organic molecule with a large aspect ratio.

[0033] In this invention, the organic molecule with a high aspect ratio comprises a chain structure. The main chain of the chain structure has no branches or only short branches. The main chain is a straight chain of at least 3 atoms, preferably at least 5 atoms, and more preferably at least 7 atoms. The short branches are branches of at least 3 atoms, more preferably at least 2 atoms. Optionally, the atoms are carbon atoms.

[0034] Optionally, the chain structure may be a molecular chain structure composed of any bond (group) or combination of bonds (groups) selected from: carbon-carbon single bond (-CC-), carbon-carbon double bond (-C=C-), ester bond (-COO-), ether bond (-O-), imino group (-NH-), amide group (-CONH-), carbonyl group (-CO-).

[0035] In the preferred embodiment of the present invention, at least a portion of the molecular backbone of component B is a flexible chain.

[0036] In this invention, the main chain of the flexible chain consists of no fewer than 5 atoms. Preferably, the flexible chain refers to a chain structure in which the molecular structure of component B contains at least one segment of 5-30 atoms.

[0037] The flexible chain, as understood, includes a chain-like structure in a molecular chain that includes interatomic bonds and has an internal rotational degree of freedom.

[0038] It should be understood that, firstly, the molecule of component B must be a molecule with a relatively long aspect ratio. This means that, when branches are present, the main chain has more atoms than the branches. More preferably, the main chain has at least two more atoms than the branches.

[0039] The molecular structure of component B does not exclude the presence of a benzene ring. It should be understood that when the chain contains a phenyl (or phenylene) group, the phenyl (or phenylene) group is part of the molecular chain.

[0040] The hydrogen bond donors and / or hydrogen bond acceptors in the molecular structure of component B are located at or near the ends of the chain molecule.

[0041] In an embodiment of the present invention, a hydrogen bond donor is provided in the molecule of component B.

[0042] Specifically, the hydrogen bond donor is selected from the carboxyl group (-COOH).

[0043] In embodiments of the present invention, component B has the following general formula: B1; R1 is an aliphatic chain compound with 1-30 carbon atoms.

[0044] B2; Among them, R2 and R3 are respectively, where R1 is an aliphatic chain compound with 1-30 carbon atoms.

[0045] In a specific embodiment of the present invention, component B is selected from: 4-(6-(acryloyloxy)hexyloxy)benzoic acid: :B3.

[0046] or, :B4.

[0047] Alternatively, 4-hexyloxybenzoic acid: :B5.

[0048] Alternatively, 4-(hex-5-en-1-yloxy)benzoic acid: :B6.

[0049] In a specific embodiment of the present invention, component B is a polymerizable acid.

[0050] Optionally, component B is a mixture, and the hydrogen bond breaking of components B with different structures can be controlled by adjusting the voltage, thereby realizing multicolor writing.

[0051] When component B is a mixture, depending on its structure, it contains hydrogen bond donors and / or hydrogen bond acceptors. Component A may have multiple hydrogen bond acceptors and / or hydrogen bond donors that cooperate with it. That is, component A has multiple hydrogen bond acceptors and / or hydrogen bond donors, and the composition contains component B molecules with various molecular structures, and component B molecules contain hydrogen bond donors and / or hydrogen bond acceptors that cooperate with component A.

[0052] In this invention, the composition is prepared by matching the molar ratio of component A and component B with their respective hydrogen bond acceptors and / or hydrogen bond donors.

[0053] This invention has discovered that the flowability of a liquid crystal composition decreases upon the addition of a chiral additive, manifested as an increase in viscosity. To overcome this excessive increase in viscosity, this invention has found that moderately increasing the content of component B can enhance the overall flowability of the liquid crystal composition.

[0054] In the preferred embodiment of this patent, based on the theoretical molar amount of component B capable of forming hydrogen bonds with component A, an excess of 5%-50% (molar ratio) of component B is optional. In particular, an excess of 5%-20% is preferred.

[0055] A second aspect of the present invention is that it provides an electric field-responsive liquid crystal composition comprising the electric field-responsive liquid crystal chiral additive composition.

[0056] In this invention, the electric field responsive liquid crystal chiral additive composition is added in a proportion of 1%-20%, preferably 5%-10%, to the liquid crystal composition.

[0057] In an optional embodiment, when the proportion of the chiral additive to the liquid crystal is higher than 5%, in order to prevent the excessive increase in the viscosity of the liquid crystal system, component B in the electric field responsive liquid crystal chiral additive composition of the present invention can be moderately excessive.

[0058] Preferably, the liquid crystal in the liquid crystal composition is a cholesteric liquid crystal.

[0059] A third aspect of the present invention is that a control component for adjusting the writing color of a liquid crystal is provided.

[0060] A first aspect of the present invention provides a control component for adjusting the writing color of a liquid crystal.

[0061] The control component for adjusting the writing color of the liquid crystal includes a liquid crystal module, a control module, a color setting module, a voltage adjustment module, and a storage module.

[0062] The liquid crystal module includes a liquid crystal layer and electrodes for applying voltage to the liquid crystal layer.

[0063] The color setting module is used to obtain color setting information for LCD writing and / or display.

[0064] In this invention, color settings can be based on user color selection, pre-set settings such as color setting information stored in memory, or color selection corresponding to the user's task type. Different colors are set for different user task types. For example, when the user sets the current task to be text writing, the handwriting color is green; when the current task is annotation writing, the handwriting color is red.

[0065] The color setting module of this invention further includes converting the set color information into an electrical signal and transmitting the color setting information to the control module. The information transmission includes both wired and wireless communication. The wireless transmission may optionally include: Bluetooth communication, infrared communication, NFC near-field communication, WiFi, and cellular network communication.

[0066] The control module includes: a processor.

[0067] The storage module includes a memory for storing the relationship between the user's handwriting and annotation colors and voltage.

[0068] The voltage regulation module in this invention is used to adjust the voltage according to requirements.

[0069] The control module generates the voltage requirement information corresponding to the color setting information and transmits the voltage requirement information to the voltage adjustment module. The voltage adjustment module adjusts the voltage on the electrode plates in the liquid crystal module according to the received voltage requirement information to realize the liquid crystal writing of the set color.

[0070] In this invention, the liquid crystal module has a liquid crystal layer comprising: a liquid crystal-filled layered structure, a liquid crystal-filled strip structure, or a liquid crystal-filled pixel unit structure.

[0071] The liquid crystal in this invention is a liquid crystal composition known to those skilled in the art, which has a corresponding writing color in response to an electric field applied to the liquid crystal. In particular, liquid crystal compositions that can form different liquid crystal molecule pitches in response to an electric field applied to the liquid crystal are available. For example, the liquid crystal composition is an electrochemically tintable liquid crystal composition, such as a cholesteric liquid crystal composition having a redox-responsive chiral dopant, for example, a cholesteric liquid crystal composition containing a chiral dopant with a ferrocene derivative structure.

[0072] In this invention, the liquid crystal writing control component further includes a position recognition module, which includes: recognizing and / or generating corresponding task response area position information (e.g., a writing area) based on the user's task (e.g., a writing task). For example, when the user writes, the position recognition generation module recognizes the writing task, sets a writing area based on the current writing point, and applies a voltage corresponding to a set writing color to the set writing area.

[0073] More specifically, the location recognition module is used to identify the response area location information of the corresponding task according to the user task, and send the location information to the control module; the control module generates voltage demand information and voltage application area location information according to the color setting information and the response area location information, and sends the voltage demand information and voltage application area location information to the voltage adjustment module; the voltage adjustment module generates the applied voltage according to the received voltage demand information, and applies the applied voltage to the set area.

[0074] In this invention, the designated area can be the entire blackboard area or a portion of the blackboard area.

[0075] In this invention, the user task is writing or marking, the position information of the response area is the position information of the current writing point, the applied voltage is a color-adjusting voltage, and the area where the voltage is applied is the color-adjusting voltage application area. The color-adjusting voltage application area should be larger than the contact area between the pen and the blackboard at the current writing point.

[0076] Because cholesteric liquid crystals can write even without power when the writing color does not need to be changed, in this invention, the voltage for setting the writing color is 0V.

[0077] In this invention, the voltage used to set the writing color is also called the color adjustment voltage.

[0078] In this invention, a color-tuning voltage set is defined, which is a set composed of set writing color voltages.

[0079] Based on the set writing color, a color voltage corresponding to the set writing color is selected from the color voltage set and applied to the writing area.

[0080] To enable multi-color writing, the color adjustment voltage set should include at least one voltage that can change the liquid crystal pitch, that is, at least one non-zero voltage.

[0081] This invention reveals that for electrically responsive tunable liquid crystal compositions, there is a time lag between the electrical response to color adjustment (corresponding to a change in the pitch of liquid crystal molecules) and the application of voltage (electric field). Therefore, during writing, it is necessary to apply a color-adjusting voltage to an area appropriately expanded beyond the current writing point. That is, the writing area to which the color-adjusting voltage is applied should be larger than the current writing point.

[0082] To more clearly represent the appropriately enlarged area, this invention defines the point where new writing is currently formed on the liquid crystal blackboard as the current writing point. It can be understood that the current writing point is the contact point between the writing tool (e.g., a pen, or a finger) and the liquid crystal blackboard. When the contact point between the writing tool and the liquid crystal blackboard is large, optionally, the current writing point can be any point within the contact area; preferably, the current writing point is the center point of the contact area.

[0083] In this invention, taking into account the normal writing speed and the liquid crystal electro-response color adjustment time, a second point is set at a position at least a distance a from the current writing point in at least one direction from the current writing point, with the current writing point as the endpoint. A color adjustment voltage application area is set that includes the current writing point and the second point, and a color adjustment voltage is applied in the area.

[0084] In this invention, the direction can be any direction around the current writing point.

[0085] In this invention, the second point can be multiple points that satisfy the distance requirement.

[0086] The distance 'a' between the second point and the current writing point can be adjusted according to the actual writing speed. One example is setting multiple second points based on different directions, with corresponding distances 'a' set for each direction.

[0087] When the distance a is adjustable, the distance a is a variable, and the distance a is selected from any value between 0.1 and 50 cm. Preferably, the distance a is any value between 0.5 and 40 cm, or any value between 1 and 30 cm, 2 and 20 cm, or 5 and 10 cm.

[0088] In one embodiment of the invention, when the direction is any direction around the current writing point, a plurality of second points are evenly distributed around the writing point. When the number of second points is sufficient, and 'a' is a fixed value, the minimum area of ​​the color-correcting voltage can be understood as a circle centered on the current writing point with a radius of 'a'.

[0089] In the technical solution of the present invention, the distance between the boundary of the area where the color adjustment voltage is applied and the current writing point is not less than a.

[0090] In a preferred embodiment of the present invention, the distance between the boundary of the region where the color-correcting voltage is applied and the current writing point is equal to the distance a.

[0091] In a preferred embodiment of the present invention, the distance between the boundary of the area where the color-correcting voltage is applied and the current writing point is no greater than 2 times the distance a. Preferably, the distance between the boundary of the area where the color-correcting voltage is applied and the current writing point is no greater than 1.5 times the distance a.

[0092] In this invention, the direction is preferably a writing prediction direction. The writing prediction direction includes: predicting the direction of the next one or more characters or character combinations relative to the current writing point based on the arrangement direction of previously written characters or character combinations; and predicting the extension direction of the next stroke or line based on the writing direction of the currently written stroke or line.

[0093] In this invention, preferably, the distance a in the writing prediction direction is longer than the distance a in the non-writing prediction direction. In particular, the distance a in the writing prediction direction is longer than the distance a in the direction opposite to or orthogonal to the writing prediction direction.

[0094] That is, in the writing prediction direction, the area where the color-correcting voltage is applied has a farther boundary from the current writing point than in other directions, especially in directions opposite to or orthogonal to the writing prediction direction, and the area where the color-correcting voltage is applied extends further in the writing prediction direction.

[0095] This is further reflected in the fact that when there are multiple second points, the distance between the second point set in the writing prediction direction and the current writing point is longer than the distance between the second point set in the non-writing prediction direction and the current writing point.

[0096] It should be understood that the second point in this invention is a virtual point, used to set and determine the application area of ​​the color-correcting voltage. Those skilled in the art do not necessarily need to set the second point to define the area where the color-correcting voltage is applied when actually setting the application range. However, the area where the color-correcting voltage is applied can be determined by setting the second point to determine whether the area is suitable and whether it falls within the protection scope of this invention.

[0097] This invention discovers that when the set color-tuning voltage application area meets the setting rules described in the second point, it can overcome the time lag between the electrical response color-tuning of the tunable liquid crystal composition and the time of voltage application, thus overcoming the problem of unstable writing color caused by this.

[0098] It should be noted that when a writing instrument or finger is in contact with the blackboard, the current writing point is the point at which the writing instrument or finger touches the blackboard at the "current" moment. New writing is formed based on this contact at the "current" moment.

[0099] It should be noted that, in order to maintain the color of the writing on the blackboard, a certain voltage can be applied to the existing writing on the blackboard, except at the current writing point. This color-adjusting voltage applied to maintain the color of the writing is also referred to as a color-maintaining voltage in this invention.

[0100] Since different handwriting colors correspond to different color holding voltages or different color holding voltage ranges, this patent defines a set of color holding voltages, which is a collection of color holding voltages.

[0101] For bistable liquid crystal compositions, especially cholesteric liquid crystals, a color-retaining voltage is not always necessary. This invention has found that the p-state structure of cholesteric liquid crystals is relatively stable. When the electrochemical products of chiral additives have good stability and / or the system viscosity is high, the pitch of the cholesteric phase liquid crystal molecules in the p-state of the electrochemically tinted liquid crystal composition is relatively stable. In this case, even if the color-retaining voltage or tinting voltage is removed, the color in the p-state remains stable. When a higher voltage is applied, the entire liquid crystal transitions to the h-state, becoming transparent, and its corresponding color disappears. In this case, the color-retaining voltage is 0V.

[0102] Furthermore, in multi-color writing, there are instances where the writing color does not need to be changed, and the writing can be done without power. In this case, the color retention voltage is also 0V.

[0103] The color retention voltage set can be a set of only 0V.

[0104] However, it is not excluded for those skilled in the art that the color holding voltage set includes non-0V voltages.

[0105] In embodiments of the present invention, the priority of the applied color-correcting voltage and color-holding voltage during writing can be adjusted according to the application area of ​​the color-correcting voltage and color-holding voltage, and the writing task requirements. Specifically, during the writing process, when the color-correcting voltage and color-holding voltage applied to the current writing point, i.e., the area surrounding the writing point, overlap, the color-correcting voltage or color-holding voltage is applied to the overlapping area according to the priority.

[0106] In one embodiment of the present invention, the priority of the color-correcting voltage applied to the current writing point is set higher than that of the color-holding voltage. That is, when writing, if the application area of ​​the color-holding voltage overlaps with the application area of ​​the color-correcting voltage, the color-correcting voltage is applied to the overlapping area.

[0107] In another embodiment of the invention, when annotating text, it is undesirable for the annotation to affect the color of existing text. Since the color-correcting voltage is applied not only to the current writing point but also to a region surrounding it, the color-maintaining voltage described in this patent has higher priority than the color-correcting voltage applied to the current writing point and / or the region surrounding it. That is, when the application area of ​​the color-maintaining voltage overlaps with the application area of ​​the color-correcting voltage, the color-maintaining voltage is applied to the overlapping area.

[0108] Existing electroresponsive tunable liquid crystal compositions achieve color tuning by altering the molecular structure of cholesteric liquid crystal chiral additives through changing the electric field (voltage), thereby adjusting the liquid crystal molecule pitch. On the other hand, applying an electric field (voltage) can also change the phase state of liquid crystal molecules, enabling transitions between Fc, P, and H states. In liquid crystal blackboards, the coordination between the color tuning voltage and the liquid crystal control voltage must be considered when setting the color tuning voltage.

[0109] In this invention, both the color adjustment voltage and the color retention voltage are lower than the liquid crystal erasure voltage.

[0110] When erasing a blackboard, to prevent accidental erasure, an erasing voltage needs to be applied to the erasing area, and a holding voltage needs to be applied to the non-erasing area. In this invention, writing can be done while erasing on the blackboard, and the writing color is not affected by the erasure. When erasing the blackboard, the color-adjusting voltage should not be less than the holding voltage (color-adjusting voltage ≥ holding voltage).

[0111] Considering the relationship between holding voltage and erasing voltage, in this invention, the color-adjusting voltage should be no less than half of the erasing voltage (color-adjusting voltage ≥ half of the erasing voltage). In this case, when erasing a portion of the blackboard, the holding voltage of the non-erasable areas remains no greater than the color-adjusting voltage. This ensures that the writing color in the non-erasable areas remains stable and unchanged during erasing.

[0112] It should be noted that the color-correcting voltage in this invention can be a set of multiple voltages. In this case, "color-correcting voltage ≥ holding voltage" should be understood as the smallest color-correcting voltage in the set of color-correcting voltages should be ≥ the holding voltage. Similarly, "color-correcting voltage ≥ half of erase voltage" should be understood as the smallest color-correcting voltage in the set of color-correcting voltages should be ≥ half of the erase voltage.

[0113] In this invention, "≥" should be understood as including two parallel technical solutions: greater than and equal to. Similarly, "not less than" should also be understood as including two parallel technical solutions: greater than and equal to.

[0114] In this invention, when the color-tuning voltage equals the holding voltage, it should be understood as being in a critical state.

[0115] In this invention, the erasing voltage is the erasing voltage applied during actual blackboard erasing.

[0116] The present invention also provides an adjustable writing color liquid crystal blackboard, which includes the control component.

[0117] The present invention also provides a control system for an adjustable writing color liquid crystal blackboard, which can realize the function of adjusting the writing color.

[0118] This invention utilizes specific chiral additives to enable flexible adjustment of the liquid crystal writing color according to actual needs. Different colors can be used to distinguish between main text and marked content, highlighting key points. This invention's adjustable writing color liquid crystal blackboard allows for free switching of writing colors according to teaching needs, which is of great significance for improving the quality of classroom teaching. Detailed Implementation

[0119] The electric field-responsive liquid crystal chiral additive composition of the present invention comprises: (Compound A1) and (Compound B3); The resulting composition containing hydrogen bonds has the following structure:

[0120] Compound A1 was obtained by esterification of isosorbide and isonicotinic acid, and compound B3 was 4-(6-(acryloyloxy)hexyloxy)benzoic acid, which is commercially available. Compounds A1 and B3 were mixed in a molar ratio of 1:1. The resulting electric field-responsive liquid crystal chiral additive composition was added to a cholesteric liquid crystal at a ratio of 10% (weight percentage) to obtain an electric field-responsive liquid crystal composition.

[0121] The liquid crystal composition is infused into a liquid crystal layer, and electrodes are further provided to obtain a liquid crystal module.

[0122] According to the present invention, a control component for adjusting the writing color of liquid crystal is provided. The control component includes a liquid crystal module, a control module, a color setting module, a voltage adjustment module, and a storage module. The liquid crystal module includes a liquid crystal layer with liquid crystal pixels as units and electrodes for applying a voltage to the liquid crystal. The liquid crystal layer is composed of cholesteric liquid crystal with an electric field-induced controllable helical structure.

[0123] According to the present invention, a control component for adjusting the writing color of liquid crystal is disclosed. The control component includes a liquid crystal module, a control module, a color setting module, a voltage adjustment module, and a storage module. The liquid crystal module includes a liquid crystal layer composed of liquid crystal pixels and electrodes for applying a voltage to the liquid crystal. The liquid crystal layer is composed of cholesteric liquid crystal with an electric field-induced controllable helical structure. When a color-adjusting voltage V1 lower than the erasing voltage is applied to the entire blackboard, the structure of the chiral additive in the liquid crystal composition changes, causing a change in the pitch of the liquid crystal in the FC state. Writing at this time yields a writing color corresponding to this voltage. For cholesteric liquid crystal, since the already written liquid crystal is in a planar state, its pitch is stable and basically unaffected by the V1 voltage, and the already written color remains essentially unchanged. When the voltage V1 is removed, the cholesteric liquid crystal in the Fc state returns to its initial pitch, and the newly written note again appears green.

[0124] During erasure, when a voltage V2 higher than the erasure voltage is applied to the erasure area, all writing in the erasure area is erased. To achieve simultaneous erasure and writing, the erasure voltage V2 and the color adjustment voltage V1 must satisfy the following condition: V1 ≥ ½ * V2. That is, V1 is greater than or equal to half of V2. For example, erasing can be performed on the upper area of ​​the blackboard while writing is performed on the lower area, and erasure does not affect the writing color. In this embodiment, the erasure voltage V2 of the LCD blackboard is 20V, and the color adjustment voltage V1 is 15V.

[0125] When voltage V2 is removed, the cholesteric liquid crystal in the Fc state returns to its initial pitch, and the newly written notes turn green again.

[0126] The above embodiments are only used to illustrate the present invention and are not intended to limit the present invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also fall within the scope of the present invention, and the patent protection scope of the present invention should be defined by the claims.

Claims

1. An electric field-responsive liquid crystal chiral additive composition, characterized in that, include: Component A and component B; Among them, component A is a chiral molecular compound that induces helical twisting of liquid crystals; Component B is used to form hydrogen bonds with component A, and the hydrogen bonds between component A and component B can be broken by applying an external electric field.

2. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Component A comprises at least one hydrogen bond donor and / or hydrogen bond acceptor, and component B comprises a hydrogen bond acceptor and / or hydrogen bond donor that interacts with component A; the hydrogen bond acceptor is selected from: carbonyl ( ), nitro (-NO2), pyridyl ( The hydrogen bond donor is selected from: hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), imino (-NH-), and mercapto (-SH) groups.

3. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, The breaking of hydrogen bonds in chiral additive compositions can be adjusted by regulating the applied electric field.

4. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, The absolute value of HTP in component A should not be less than 20 (μm). -1 In a preferred embodiment, the absolute value of HTP of component A should be not less than 25 (μm). -1 Preferably, it is not less than 40 (μm) -1 More preferably, it should be not less than 70 (μm) -1 ).

5. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Component A is selected from at least one of the following: chiral additives with isosorbide skeleton, chiral additives with binaphthol skeleton, and chiral additives with 2,2'-substituted biphenyl skeleton.

6. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Component A is a compound having the following structure: Compound A1; Compound A2.

7. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, The molecule of component B comprises a chain structure; preferably, the main chain of the chain structure has no branches or only short branches; more preferably, the main chain is a straight chain of not less than 3 atoms, more preferably a straight chain of not less than 5 atoms, more preferably a straight chain of not less than 7 atoms, and the short branches are branches of not more than 3 atoms, more preferably branches of not more than 2 atoms; wherein, preferably, at least part of the molecular main chain is a flexible chain, preferably, the main chain of the flexible chain is composed of not less than 5 atoms, and more preferably, the flexible chain is a chain structure containing 5-30 atoms.

8. The electric field-responsive liquid crystal chiral additive composition according to claim 7, characterized in that, The chain structure is a molecular chain structure composed of any bond (group) or combination of bonds (groups) selected from: carbon-carbon single bond (-CC-), carbon-carbon double bond (-C=C-), ester bond (-COO-), ether bond (-O-), imino group (-NH-), amide group (-CONH-), carbonyl group (-CO-).

9. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Component B is selected from compounds having the following general formula: ：B1； R1 is an aliphatic chain compound with 1-30 carbon atoms; ：B2； Among them, R1, R2, and R3 are aliphatic chains containing 1 to 30 carbon atoms.

10. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Component B is selected from compounds having the following structures: ：B3。 or, ：B4。 or, ：B5。 or,: ：B6。 11. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Component B is a polymerizable acid.

12. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, The molecule of component A has multiple hydrogen bond acceptors and / or hydrogen bond donors, and the composition contains component B molecules with various molecular structures, and component B molecules have hydrogen bond donors and / or hydrogen bond acceptors that cooperate with component A.

13. The electric field-responsive liquid crystal chiral additive composition according to claim 1, characterized in that, Based on the theoretical molar amount of component B that forms hydrogen bonds with component A, component B is in 0%-50% molar excess, preferably in 5%-20% molar excess.

14. An electric field-responsive liquid crystal composition, characterized in that, The electric field responsive liquid crystal chiral additive composition comprising any one of claims 1-13.

15. The electric field-responsive liquid crystal composition according to claim 14, characterized in that, The liquid crystal in the liquid crystal composition is a cholesteric phase liquid crystal.

16. A control component for adjusting the writing color of a liquid crystal blackboard, characterized in that, Includes an LCD module, a control module, a color setting module, and a voltage regulation module; The liquid crystal module includes: a liquid crystal cell and electrodes for applying voltage to the liquid crystal cell; a color setting module for obtaining color setting information for writing and / or displaying the liquid crystal and sending the color setting information to the control module; the control module includes: a processor, which receives and generates voltage requirement information corresponding to the color based on the color setting information and transmits the voltage requirement information to the voltage adjustment module; the voltage adjustment module generates an application voltage based on the received voltage requirement information and applies the application voltage to the electrodes in the liquid crystal module.

17. The control component according to claim 16, characterized in that, The liquid crystal cell is filled with a liquid crystal composition that is an electric field responsive liquid crystal composition as described in any one of claims 14-15.

18. The control component according to claim 16, characterized in that, It further includes a location recognition module, which is used to identify the location information of the response area of ​​the corresponding task according to the user task, and send the location information to the control module; The control module generates voltage requirement information and voltage application area location information based on color setting information and response area location information, and sends the voltage requirement information and voltage application area location information to the voltage adjustment module. The voltage adjustment module generates an application voltage based on the received voltage requirement information and applies the application voltage to a set area, which is larger than the contact area between the LCD blackboard writing tool and the LCD blackboard.

19. The control component according to claim 16, characterized in that, When partially erasing the blackboard, the applied voltage includes a color-correcting voltage, which is greater than or equal to half of the erasing voltage.

20. The control component according to claim 16, characterized in that, It further includes a storage module.

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