CN113759623B - Liquid crystal writing board, display method thereof and writing device - Google Patents
Liquid crystal writing board, display method thereof and writing device Download PDFInfo
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- CN113759623B CN113759623B CN202111044882.8A CN202111044882A CN113759623B CN 113759623 B CN113759623 B CN 113759623B CN 202111044882 A CN202111044882 A CN 202111044882A CN 113759623 B CN113759623 B CN 113759623B
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
- G02F1/1391—Bistable or multi-stable liquid crystal cells
Abstract
The application provides a liquid crystal writing board, a display method thereof and a writing device, wherein a bistable liquid crystal layer in the liquid crystal writing board comprises a plurality of pixel units, each pixel unit comprises a first liquid crystal subunit, a second liquid crystal subunit and a third liquid crystal subunit which are arranged side by side along the direction parallel to a first transparent substrate, and any two adjacent liquid crystal subunits are isolated by a transparent spacer; the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are configured to reflect red light, green light and blue light respectively under the action of a first preset electric field, and are configured to be in a scattering state under the action of a second preset electric field. The bistable liquid crystal layer displays white under the action of a first preset electric field, each liquid crystal subunit is converted into a scattering state under the action of a second preset electric field, the color of the shading substrate is displayed, black or color handwriting can be written under a white background, and the handwriting definition of the writing board is greatly improved.
Description
Technical Field
The application relates to the technical field of display, in particular to a liquid crystal writing board, a display method thereof and a writing device.
Background
At present, three types of education writing boards are provided on the market, namely a traditional blackboard, a white plastic board and an electronic handwriting blackboard, wherein the traditional blackboard is black frosted glass, white chalk is required to be used for writing, daily and monthly chalk dust influences human health such as upper respiratory tract mucous membrane stimulation, a white plastic board is required to purchase a pigment pen, the condition that the pigment pen is free of ink is frequently encountered, and the problem of unclean wiping is encountered when the traditional blackboard and the white board are long.
Therefore, with the development of the liquid crystal display technology, the liquid crystal writing board is increasingly widely used in the fields of education, business application and the like. However, the common writing board on the market has low comprehensive display brightness and contrast, so that writing definition is low and user experience is great.
Disclosure of Invention
Aiming at the problems, the application provides a liquid crystal writing board, a display method thereof and a writing device, which can solve the technical problem of lower handwriting definition of an electronic writing board in the prior art.
In a first aspect, the present application provides a liquid crystal writing board comprising: a first transparent substrate and a light shielding substrate which are oppositely arranged, and a bistable liquid crystal layer positioned between the first transparent substrate and the light shielding substrate;
Wherein, the first transparent substrate is provided with a first transparent electrode plate at one side close to the bistable liquid crystal layer;
the light shielding substrate is provided with a second transparent electrode plate at one side close to the bistable liquid crystal layer;
the bistable liquid crystal layer comprises a plurality of pixel units, each pixel unit comprises a first liquid crystal subunit, a second liquid crystal subunit and a third liquid crystal subunit which are arranged side by side along the direction parallel to the first transparent substrate, and any two adjacent liquid crystal subunits are isolated by a transparent spacer;
the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are configured to reflect red light, green light and blue light respectively under the action of a first preset electric field, and are configured to be in a scattering state under the action of a second preset electric field.
In some embodiments, in the above liquid crystal writing board, the second preset electric field is greater than the first preset electric field;
when the bistable liquid crystal layer is in the first preset electric field and one side of the first transparent substrate far away from the bistable liquid crystal layer is pressed, the electric field of the bistable liquid crystal layer at the pressing position is converted from the first preset electric field to the second preset electric field.
In some embodiments, the liquid crystal writing board further includes a touch component.
In some embodiments, in the above liquid crystal writing board, the first transparent electrode plate includes a plurality of first sub-electrodes arranged in an array;
the second transparent electrode plate comprises a plurality of second sub-electrodes which are arranged in an array.
In some embodiments, in the above liquid crystal writing board, the color of the shading substrate is configured as a color of writing trace.
In some embodiments, in the above liquid crystal writing board, the color of the light shielding substrate is selected from any color other than white.
In some embodiments, in the above liquid crystal writing board, the materials of the first liquid crystal subunit, the second liquid crystal subunit, and the third liquid crystal subunit each include cholesteric liquid crystal.
In some embodiments, in the above liquid crystal writing board, the liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are in a planar texture state under the first preset electric field, and are in a focal conic texture state under the second preset electric field.
In some embodiments, in the above liquid crystal writing board, the light shielding substrate includes a second transparent substrate, and a light shielding layer disposed between the second transparent substrate and the second transparent electrode plate.
In some embodiments, in the above liquid crystal writing board, the light shielding layer is provided with a plurality of protrusions on a side close to the second transparent electrode plate.
In some embodiments, the liquid crystal writing board further includes:
and a driving unit electrically connected to the first transparent electrode plate and the second transparent electrode plate, the driving unit being configured to apply a voltage between the first transparent electrode plate and the second transparent electrode plate to apply a corresponding electric field to the bistable liquid crystal layer.
In a second aspect, the present application provides a display method of the liquid crystal writing board according to any one of the first aspects, comprising:
applying a first voltage between the first transparent electrode plate and the second transparent electrode plate to apply the first preset electric field to the bistable liquid crystal layer, so that the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit respectively reflect red light, green light and blue light under the action of the first preset electric field, and the bistable liquid crystal layer displays white under the action of the first preset electric field;
in response to a writing operation applied to one side of the first transparent substrate far away from the bistable liquid crystal layer, an electric field of the bistable liquid crystal layer at a writing position is converted from the first preset electric field to the second preset electric field, so that the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit at the writing position are converted into scattering states under the action of the second preset electric field, and the bistable liquid crystal layer displays the color of the shading substrate at the writing position.
In some embodiments, the display method of the liquid crystal writing board further includes:
in response to a received erasing instruction, applying a third voltage between the first transparent electrode plate and the second transparent electrode plate to apply a third preset electric field to the bistable liquid crystal layer, so that all liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are converted into a vertical texture state under the action of the third preset electric field; wherein the third preset electric field is greater than the second preset electric field;
and returning to the step of applying a first voltage between the first transparent electrode plate and the second transparent electrode plate, so that all the liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are converted into a plane texture state from the vertical texture state under the action of the first preset electric field, and the bistable liquid crystal layer is enabled to resume displaying white.
In some embodiments, the display method of the liquid crystal writing board further includes:
in response to a received erasing instruction, applying a third voltage between a first sub-electrode of the first transparent electrode plate and a second sub-electrode of the second transparent electrode plate at the writing position, so as to apply a third preset electric field to the bistable liquid crystal layer at the writing position, and enabling liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit at the writing position to be converted into a vertical texture state under the action of the third preset electric field; wherein the third preset electric field is greater than the second preset electric field;
And returning to the step of applying a first voltage between the first transparent electrode plate and the second transparent electrode plate, so that the liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit at the writing position are converted into a plane texture state from the vertical texture state under the action of the first preset electric field, and the bistable liquid crystal layer is enabled to resume displaying white.
In a third aspect, the present application provides a writing device comprising a liquid crystal writing board according to any one of the first aspects and a writing pen.
By adopting the technical scheme, at least the following technical effects can be achieved:
the application provides a liquid crystal writing board, a display method thereof and a writing device, wherein the liquid crystal writing board comprises a first transparent substrate, a shading substrate and a bistable liquid crystal layer, wherein the first transparent substrate and the shading substrate are oppositely arranged; the bistable liquid crystal layer comprises a plurality of pixel units, each pixel unit comprises a first liquid crystal subunit, a second liquid crystal subunit and a third liquid crystal subunit which are arranged side by side along the direction parallel to the first transparent substrate, and any two adjacent liquid crystal subunits are isolated by a transparent spacer; the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are configured to reflect red light, green light and blue light respectively under the action of a first preset electric field, and are configured to be in a scattering state under the action of a second preset electric field. By arranging three liquid crystal subunits which can reflect red light, green light and blue light respectively under the action of a first preset electric field in each pixel unit of the bistable liquid crystal layer, the bistable liquid crystal layer displays white under the action of the first preset electric field, and each liquid crystal subunit is converted into a scattering state under the action of a second preset electric field, the color of the shading substrate is displayed, black or color handwriting can be written under a white background, the display brightness and contrast are greatly improved, the handwriting definition of the writing board is greatly improved, and the user experience is improved.
Drawings
The accompanying drawings are included to provide a further understanding of the application, and are incorporated in and constitute a part of this specification, illustrate the application and together with the description serve to explain, without limitation, the application. In the drawings:
FIG. 1 is a schematic cross-sectional view of a liquid crystal writing board according to an exemplary embodiment of the present application;
FIG. 2 is a schematic diagram of a pixel arrangement of a liquid crystal writing board according to an exemplary embodiment of the present application;
fig. 3 (a) is a schematic diagram showing an arrangement structure of cholesteric liquid crystal molecules in a planar texture state according to an exemplary embodiment of the present application;
FIG. 3 (b) is a schematic diagram showing an arrangement structure of cholesteric liquid crystal molecules in a focal conic texture state according to an exemplary embodiment of the application;
FIG. 3 (c) is a schematic diagram showing an arrangement structure of cholesteric liquid crystal molecules in a vertical texture state according to an exemplary embodiment of the application;
FIG. 4 is a schematic diagram showing the reflectivity versus voltage of a liquid crystal subunit in an initial state according to an exemplary embodiment of the present application;
fig. 5 is a schematic cross-sectional view showing a liquid crystal writing board in a written state according to an exemplary embodiment of the present application;
FIG. 6 is a graph showing the reflectivity versus voltage of a liquid crystal subcell in the written state according to an exemplary embodiment of the present application;
FIG. 7 is a graph showing the reflectivity versus voltage of a liquid crystal subcell in the erased state according to an exemplary embodiment of the application;
in the drawings, wherein like parts are designated by like reference numerals throughout, the drawings are not to scale;
the reference numerals are:
11-a first transparent substrate; 12-a light-shielding substrate; 121-a second transparent substrate; 122-a light shielding layer; 13-a bistable liquid crystal layer; 131-a first liquid crystal subunit; 132-a second liquid crystal subunit; 133-a third liquid crystal subunit; 134-transparent spacers; 14-a first transparent electrode plate; 15-a second transparent electrode plate; 16-drive unit.
Detailed Description
The following will describe embodiments of the present application in detail with reference to the drawings and examples, thereby solving the technical problems by applying technical means to the present application, and realizing the corresponding technical effects can be fully understood and implemented accordingly. The embodiment of the application and the characteristics in the embodiment can be mutually combined on the premise of no conflict, and the formed technical scheme is within the protection scope of the application. In the drawings, the size of layers and regions, as well as the relative sizes, may be exaggerated for clarity. Like numbers refer to like elements throughout.
It will be understood that, although the terms "first," "second," "third," etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present application.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.
In the following description, for the purpose of providing a thorough understanding of the present application, detailed structures and steps are presented in order to illustrate the technical solution presented by the present application. Preferred embodiments of the present application are described in detail below, however, the present application may have other embodiments in addition to these detailed descriptions.
The application provides a liquid crystal writing board, which comprises a first transparent substrate 11 and a shading substrate 12 which are oppositely arranged, and a bistable liquid crystal layer 13 positioned between the first transparent substrate 11 and the shading substrate 12, as shown in fig. 1.
The first transparent substrate 11 is provided with a first transparent electrode plate 14 at a side close to the bistable liquid crystal layer 13.
The light shielding substrate 12 is provided with a second transparent electrode plate 15 on a side close to the bistable liquid crystal layer 13.
The bistable liquid crystal layer 13 includes a plurality of pixel units (not shown in the drawing), as shown in fig. 2, each of which includes a first liquid crystal sub-unit 131, a second liquid crystal sub-unit 132, and a third liquid crystal sub-unit 133 disposed side by side in a direction parallel to the first transparent substrate 11, and any adjacent two liquid crystal sub-units are separated by a transparent spacer 134.
The transparent spacers 134 are disposed between two adjacent liquid crystal sub-units in the same pixel unit, and also disposed between two adjacent pixel units, and the transparent spacers 134 play a role in blocking light without blocking light.
In some embodiments, the front projection of the first, second and third liquid crystal subunits 131, 132, 133 onto the light-shielding substrate 12 has a width W of at least 100 μm and a length L of at least 40 μm.
In some embodiments, the corresponding pixel cell has a width W of at least 100 μm and a length L of at least 120 μm.
The first, second and third liquid crystal subunits 131, 132 and 133 are configured to reflect red, green and blue light, respectively, under the action of a first preset electric field, and are configured to be in a scattering state under the action of a second preset electric field.
The first, second and third liquid crystal sub-units 131, 132 and 133 reflect red, green and blue light, respectively, under the action of the first preset electric field, and the pixel unit shows white.
Under the action of the second preset electric field, the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 are in a scattering state, and the pixel unit displays the color of the light shielding substrate 12.
In some embodiments, the liquid crystal tablet is in an initial state, the entire bistable liquid crystal layer 13 is under the action of the first preset electric field, and the entire bistable liquid crystal layer 13 displays white color, and the liquid crystal tablet is a whiteboard.
The magnitudes of the second preset electric field and the first preset electric field depend on the voltage and the distance between the first transparent electrode plate 14 and the second transparent electrode plate 15.
In some embodiments, when the bistable liquid crystal layer 13 is under the first preset electric field and the side (writing side) of the first transparent substrate 11 away from the bistable liquid crystal layer 13 is pressed (including writing pressing by a writing pen or a finger of a user), at the pressing position, the distance between the first transparent electrode plate 14 and the second transparent electrode plate 15 is reduced, the electric field of the bistable liquid crystal layer 13 at the pressing position is increased, and the electric field can be converted into the second preset electric field by the first preset electric field, and the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 of the bistable liquid crystal layer 13 at the pressing position are converted into scattering states by the states reflecting red light, green light and blue light, displaying the color of the light shielding substrate 12, and realizing displaying the writing on the white liquid crystal writing board.
In some embodiments, the liquid crystal tablet 11 includes a touch assembly.
For example, the touch component may be an infrared touch component (not shown in the figure). The infrared touch control component can be arranged around the first transparent substrate and used for positioning a touch control or writing position of a user on the liquid crystal writing board 11.
In some embodiments, the touch component may be disposed on a side (writing side) of the first transparent substrate 11 away from the bistable liquid crystal layer 13; the touch component can be a capacitive touch component or a resistive touch component.
Further, in some embodiments, the first transparent electrode plate 14 includes a plurality of first sub-electrodes (not shown) arranged in an array, and the second transparent electrode plate 15 includes a plurality of second sub-electrodes (not shown) arranged in an array.
Further, in some embodiments, the first sub-electrode and the second sub-electrode are in one-to-one correspondence.
Correspondingly, when the touch component recognizes that the writing side of the first transparent substrate 11 is touched (for example, a user writes touch operation), the driving unit 16 can be controlled to load a preset voltage between the first sub-electrode and the second sub-electrode at the touch position, so that the bistable liquid crystal layer 13 generates a second preset electric field at the touch position, and the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 at the touch position are converted from the state of reflecting red light, green light and blue light into the scattering state, the color of the light shielding substrate 12 is displayed, and writing is displayed on the white liquid crystal writing board.
Under the structure of the writing board, a user can realize writing operation and writing display on the writing board through touch control, and writing sensitivity can be improved.
It should be noted that, in the writing board structure provided with the touch assembly, when the first liquid crystal subunit 131, the second liquid crystal subunit 132, and the third liquid crystal subunit 133 can maintain the states of respectively reflecting red light, green light, and blue light under the action of the 0 electric field, the magnitude of the first preset electric field may be 0, that is, the magnitude of the voltage applied between the first transparent electrode plate 14 and the second transparent electrode plate 15 may be 0V in the initial state of displaying white.
In some embodiments, the color of the occlusion substrate 12 is configured as the color of the writing trace.
In some embodiments, the color of the light shielding substrate 12 is selected from any color other than white, which may be black or colored, and may be set according to practical requirements.
According to the scheme for displaying the handwriting on the white liquid crystal writing board, the display brightness and contrast of the writing board are greatly improved, the handwriting definition of the writing board is greatly improved, and the user experience is improved.
In some embodiments, the materials of the first, second and third liquid crystal subcells 131, 132 and 133 include cholesteric liquid crystals having bistable properties or nematic liquid crystals treated by a special alignment method that can achieve bistable states.
In some embodiments, the materials of the first, second, and third liquid crystal subunits 131, 132, and 133 each comprise cholesteric liquid crystals.
Cholesteric liquid crystals have a unique helical alignment, the liquid crystal molecules are aligned in layers twisted, the molecules lie flat in layers, the layers being parallel to each other, the molecules in each layer tend to align parallel to each other like a nematic phase, but the directors of the molecules rotate substantially uniformly and continuously along the normal to the layer plane, the layer spacing when the directors rotate 360 ° being referred to as the pitch P0. Cholesteric liquid crystals include Planar Texture (P-state), focal conic Texture (Focal Conic Texture, FC-state) and Homeotropic (H-state). Wherein the planar texture state (P-state) and focal conic texture state (FC-state) can be stably maintained without voltage maintenance. As shown in fig. 3 (a), when the cholesteric liquid crystal exhibits a planar texture state (P-state), the liquid crystal molecules spatially exhibit a helical arrangement around a helical axis perpendicular to the substrate surface, and when light is incident on the liquid crystal surface, the liquid crystal molecules selectively reflect light of a specific wavelength λ. As shown in fig. 3 (b), when cholesteric liquid crystal is in a focal conic texture state (FC state), liquid crystal molecules are still in a spiral arrangement, but the directions of the spiral axes of the liquid crystal domains are randomly distributed, the molecules are in a multi-domain state, and incident light is scattered at the boundary between adjacent liquid crystal domains due to abrupt change of refractive index, so that the incident light can pass through the color of the underlying substrate. A barrier with a certain height exists between the plane texture state (P-state) and the focal conic texture state (FC-state), the barrier can be overcome by an externally applied electric field, the transition between the plane texture state (P-state) and the focal conic texture state (FC-state) is realized, if the cholesteric liquid crystal is initially in the plane texture state (P-state), after the electric field is increased to a threshold electric field (such as a second preset electric field), the transition from the plane texture state (P-state) to the focal conic texture state (FC-state) occurs, the focal conic texture state (FC-state) is steady, even if the electric field or the voltage is reduced to zero, the focal conic texture state (FC-state) is kept all the time, the externally applied electric field is further increased to a saturated electric field (such as a third preset electric field, and the focal conic texture state (FC-state) is converted to a vertical structure state (H-state) as shown in fig. 3 (c), and if the voltage is rapidly reduced to a certain threshold or zero, the liquid crystal is converted to the initial plane texture state (P-state) and the focal conic texture state (FC-state) can be realized by pulsing the vertical structure (H-state) to a high voltage state).
Correspondingly, in the present embodiment, the liquid crystal molecules in the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 are in a planar texture state (P-state) under a first preset electric field, and are in a focal conic texture state (FC-state) under a second preset electric field.
The first, second and third liquid crystal subunits 131, 132 and 133 induce formation of different liquid crystal domains using polymers, have different directions of helical axes of liquid crystals within the domains, have different effective refractive indexes, and can selectively reflect light of a specific wavelength λ in a planar texture state (P-state) so as to reflect blue light, green light and red light, respectively.
Correspondingly, the transparent shielding object can be a polymer network, can induce cholesteric liquid crystal to form different liquid crystal domains and reflect light with different spectrums.
Correspondingly, the bistable liquid crystal layer 13 may be prepared by forming the transparent spacers 134 on the substrate now, and then forming the first, second and third liquid crystal subcells 131, 132 and 133 at the corresponding positions by a fine process such as instillation, thereby forming the bistable liquid crystal layer 13.
Correspondingly, when the liquid crystal writing board is in an initial state, the whole bistable liquid crystal layer 13 is under the action of a first preset electric field, liquid crystal molecules in the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 are in a plane texture state (P state) under the first preset electric field, blue light, green light and red light are respectively reflected, the whole bistable liquid crystal layer 13 shows white, and at the moment, the liquid crystal writing board is a writing whiteboard.
When the bistable liquid crystal layer 13 is under the first preset electric field and the side (writing side) of the first transparent substrate 11 far from the bistable liquid crystal layer 13 is pressed (including writing pressing by a writing pen or a finger of a user), at the pressing position, the distance between the first transparent electrode plate 14 and the second transparent electrode plate 15 is reduced, the electric field of the bistable liquid crystal layer 13 at the pressing position is increased, the electric field can be converted from the first preset electric field to the second preset electric field, the liquid crystal molecules in the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 at the pressing position are converted from the planar texture state (P state) to the focal conic texture state (FC state), scattering occurs, the bistable liquid crystal layer 13 displays the color of the light shielding substrate 12 at the pressing position, and writing is displayed on the white liquid crystal writing board.
And the focal conic texture state (FC state) is a stable state, even if the pressing applied at the pressing position is reduced or vanished, the electric field applied to the bistable liquid crystal layer 13 is restored to the initial state (first preset electric field), and handwriting on the liquid crystal writing board is not vanished.
Correspondingly, in the writing board structure provided with the touch assembly, when the liquid crystal molecules of the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 can maintain the planar texture state (P-state) under the action of the 0 electric field, the magnitude of the first preset electric field may be 0, that is, the magnitude of the voltage applied between the first transparent electrode plate 14 and the second transparent electrode plate 15 may be 0V in the initial state of displaying white.
In some embodiments, the light shielding substrate 12 includes a second transparent substrate 121, and a light shielding layer 122 disposed between the second transparent substrate 121 and the second transparent electrode plate 15.
In some embodiments, the material of the light shielding layer 122 may be a black matrix layer or a color photoresist layer.
In some embodiments, the material of the second transparent substrate 121 may be the same as that of the first transparent substrate 11 described above, and may be glass or a transparent PET protective film.
In some embodiments, the material of the second transparent substrate 121 may be different from that of the first transparent substrate 11, and preferably, in order to improve the writing sensitivity of the writing board, the first transparent substrate 11 may be made of polyethylene terephthalate with a higher elastic modulus, and the second transparent substrate 121 may be made of glass.
In some embodiments, the light shielding layer 122 is provided with a plurality of protrusions on a side close to the second transparent electrode plate 15, so that when the liquid crystal molecules of the bistable liquid crystal layer 13 are in the focal conic texture state (FC state), light passes through the bistable liquid crystal layer 13 and the second transparent electrode plate 15, and diffuse reflection occurs on the side close to the second transparent electrode plate 15 of the light shielding layer 122, so that the color of the light shielding substrate 12 displayed by the bistable liquid crystal layer 13 is more obvious, and writing is more obvious.
In some embodiments, the liquid crystal writing board further includes: and a driving unit 16 electrically connected to the first transparent electrode plate 14 and the second transparent electrode plate 15, the driving unit 16 being configured to apply a voltage between the first transparent electrode plate 14 and the second transparent electrode plate 15 to apply a corresponding electric field to the bistable liquid crystal layer 13.
In some embodiments, the driving unit 16 is configured to apply a corresponding voltage between the first transparent electrode plate 14 and the second transparent electrode plate 15 according to an on or erase command of a user to apply a corresponding electric field to the bistable liquid crystal layer 13.
In some embodiments, corresponding to the structure of the writing board provided with the touch assembly, the driving unit 16 may be configured to apply corresponding voltages between all the first sub-electrodes and the second sub-electrodes according to an erase command of a user, so that the bistable liquid crystal layer 13 is restored to an initial state (whiteboard state) as a whole, and the writing trace is erased. Alternatively, the driving unit 16 may be configured to apply a corresponding voltage between the first sub-electrode and the second sub-electrode whose voltage states are not the initial states according to an erase instruction of a user, so that only the liquid crystal molecules at the position where the writing is performed are restored to the initial states, and the writing may be erased as well.
Alternatively, when the touch component recognizes that the writing side of the first transparent substrate 11 is erased, the driving unit 16 may be controlled to load a preset voltage to the first sub-electrode and the second sub-electrode at the touch position, so that the bistable liquid crystal layer 13 generates a third preset electric field at the touch position, and the third preset electric field is greater than a barrier for converting the cholesteric liquid crystal molecules into a vertical texture state (H state), so that the liquid crystal molecules in the first liquid crystal sub-unit 131, the second liquid crystal sub-unit 132 and the third liquid crystal sub-unit 133 at the touch position are converted into an unstable vertical texture state (H state) under the action of the third preset electric field. Finally, when the initial voltage (i.e., the voltage for maintaining the planar texture state of the liquid crystal molecules) is restored between the first sub-electrode and the second sub-electrode, the cholesteric liquid crystal molecules in the bistable liquid crystal layer 13 are directly restored to the stable planar texture state (P-state) from the unstable vertical texture state (H-state), so that the bistable liquid crystal layer 13 is restored to display white, and the initial state is restored, thereby realizing the local erasure.
It will be appreciated that when all of the liquid crystal molecules in the first, second and third liquid crystal subunits 131, 132 and 133 are subjected to the third predetermined electric field at the same time or at similar times, the entire erasing of the liquid crystal writing board 11 can be achieved.
According to the application, three liquid crystal subunits capable of reflecting red light, green light and blue light respectively under the action of the first preset electric field are arranged in each pixel unit of the bistable liquid crystal layer 13, so that the bistable liquid crystal layer 13 displays white under the action of the first preset electric field, and each liquid crystal subunit is converted into a scattering state under the action of the second preset electric field, the color of the shading substrate 12 is displayed, black or color handwriting can be written under a white background, the display brightness and contrast are greatly improved, the writing definition of the writing board is greatly improved, and the user experience is improved.
The application also provides a display method of the liquid crystal writing board, which comprises the following steps:
step S110: a first voltage is applied between the first transparent electrode plate 14 and the second transparent electrode plate 15 to apply a first preset electric field to the bistable liquid crystal layer 13, so that the first, second and third liquid crystal subunits 131, 132 and 133 reflect red light, green light and blue light, respectively, under the action of the first preset electric field, thereby causing the bistable liquid crystal layer 13 to display white color under the action of the first preset electric field.
In some embodiments, when the materials of the first, second and third liquid crystal subcells 131, 132 and 133 are made to be cholesteric liquid crystals, as shown in fig. 4, in an initial state, a first voltage V is applied between the first and second transparent electrode plates 14 and 15 a At this time, the writing board is not pressed, and the equivalent voltages at the respective positions of the bistable liquid crystal layer 13 are V a And V is a Is kept unchanged and is at a first voltage V a Less than or equal to the maximum voltage V of the bistable liquid crystal layer 13 in the planar texture state (P state) w To apply a first preset electric field to the bistable liquid crystal layer 13, so that the liquid crystal molecules in the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 are in a planar texture state (P-state) under the action of the first preset electric field, and respectively reflect red light, green light and blue light, so that the bistable liquid crystal layer 13 displays white under the action of the first preset electric field.
Due to the first voltage V a ≤V w Even V w At 0V results in a first voltage V a At 0V, since each liquid crystal subunit is already plane-wovenThe structure state (P-state), each liquid crystal subunit is always in the plane structure state (P-state) during the voltage application and after the voltage removal is stable, the reflectivity is unchanged, at this time, the reflectivity is Rp, the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 respectively reflect red light, green light and blue light, and the whole liquid crystal subunit can reflect the whole visible light to be white.
The application of the first voltage is effected by the drive unit 16.
Step S120: in response to a writing operation applied to a side of the first transparent substrate 11 remote from the bistable liquid crystal layer 13, the electric field of the bistable liquid crystal layer 13 at the writing position is converted from a first preset electric field to a second preset electric field, so that the first liquid crystal sub-unit 131, the second liquid crystal sub-unit 132 and the third liquid crystal sub-unit 133 at the writing position are converted into a scattering state under the action of the second preset electric field, and the bistable liquid crystal layer 13 displays the color of the light shielding substrate 12 at the writing position.
In some embodiments, the second preset electric field is greater than the first preset electric field, as shown in fig. 5, the electric field change at the writing position may be a decrease in the distance between the first transparent electrode plate 14 and the second transparent electrode plate 15 due to the writing press, when the distance between the first transparent electrode plate 14 and the second transparent electrode plate 15 is decreased to a value that is greater than the potential barrier of the cholesteric liquid crystal molecules from the planar texture state (P-state) to the focal conic texture state (FC-state), that is, the second preset electric field, the liquid crystal molecules in the first liquid crystal subunit 131, the second liquid crystal subunit 132, and the third liquid crystal subunit 133 at the writing position are transformed from the planar texture state (P-state) to the focal conic texture state (FC-state) by the second preset electric field, so that the bistable liquid crystal layer 13 displays the color of the light shielding substrate 12 at the writing position.
As shown in fig. 6, in the writing state, the voltage applied between the first transparent electrode plate 14 and the second transparent electrode plate 15 is still the first voltage V a ＝V w The equivalent voltage of bistable liquid crystal layer 13 (liquid crystal cell) at the unwritten position is still V a ＝V w The liquid crystal molecules at the unwritten locations remain in a planar textureThe state (P state) is that the writing board displays the color of reflecting the whole visible light and presents white, and the display principle is the same as that of the initial state; when writing, the distance between electrode plates at the pressed position becomes smaller, so that the electric field intensity between the electrode plates is increased, and the equivalent voltage in bistable liquid crystal layer 13 at the pressed position is assumed to be V f At this time, V f At V K (minimum voltage at which cholesteric liquid crystal reaches FC state) and V g In the (maximum FC-state voltage of cholesteric liquid crystal) interval, V is different according to the written pressing force f Different, V K And V g The specific value of (2) is determined according to the properties of bistable liquid crystal materials, when V K ≤V f ≤V g When the liquid crystal molecules are changed from the P-state to the FC-state, the reflectance is reduced from Rp to Rfc, the liquid crystal subcell is scattered, and the display color at the pressed position is the color of the light shielding substrate 12, which may be black or color. Even if the pressing disappears when the writing is stopped, the voltage of the bistable liquid crystal layer 13 (liquid crystal cell) at both the written position and the unwritten position is restored to the original state, i.e., the voltage at each position is V a ＝V w The electric field strength at the previously pressed position is restored to the original magnitude, but the liquid crystal molecules of the written area maintain a stable FC state as long as the voltage does not break through V g This part of the liquid crystal molecules remains unchanged in the FC state. Thus, a color differentiation is achieved between written and unwritten positions, black or colored writing being displayed on the whiteboard.
In addition, for the writing board structure provided with the touch assembly, in response to a writing operation applied to a side of the first transparent substrate 11 away from the bistable liquid crystal layer 13, a second voltage may be applied between the first sub-electrode and the second sub-electrode at the writing position by the driving unit 16, so that an electric field of the bistable liquid crystal layer 13 at the writing position is converted from a first preset electric field to a second preset electric field, so that the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 at the writing position are converted into a scattering state under the action of the second preset electric field, thereby causing the bistable liquid crystal layer 13 to display the color of the light shielding substrate 12 at the writing position.
Step S130: in response to the received erasing command, a third voltage is applied between the first transparent electrode plate 14 and the second transparent electrode plate 15 to apply a third preset electric field to the bistable liquid crystal layer 13, so that liquid crystal molecules in all the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 are converted into a vertical texture state under the action of the third preset electric field; wherein the third preset electric field is greater than the second preset electric field.
When the driving unit 16 applies the third preset electric field to the bistable liquid crystal layer 13, the cholesteric liquid crystal molecules at the writing position (the position with writing) are converted from the focal conic texture state (FC state) to the vertical texture state (H state), and the cholesteric liquid crystal molecules at the non-writing position (the position without writing) are converted from the planar texture state (P state) to the focal conic texture state (FC state) and then to the vertical texture state (H state), but the cholesteric liquid crystal molecules are directly converted from the focal conic texture state (FC state) to the vertical texture state (H state) or from the planar texture state (P state) to the focal conic texture state (FC state) and then to the vertical texture state (H state), both the conversion times are fast, and can be regarded as being nearly completed simultaneously.
As shown in fig. 7, when the liquid crystal writing board is in an erased state, a third voltage V is applied between the first transparent electrode plate 14 and the second transparent electrode plate 15 b ，V b Equal to the barrier voltage V at which cholesteric liquid crystal molecules are converted to H state p Wherein V is w ＜V g ＜V p ，V p The specific value is determined according to the properties of different bistable liquid crystal materials, in the erased state, the first transparent substrate 11 is not pressed, the distance between the first transparent electrode plate 14 and the second transparent electrode plate 15 is the original state, and the equivalent voltage of the bistable liquid crystal layer 13 (liquid crystal cell) is equal to V p At this time, the liquid crystal in the bistable liquid crystal layer 13 at the position where the writing is pressed is changed from the FC state to the H state, and the liquid crystal molecules in the bistable liquid crystal layer 13 at the position where the writing is not pressed are changed from the P state to the FC state and then to the H state.
Step S140: returning to the step of applying the first voltage between the first transparent electrode plate 14 and the second transparent electrode plate 15 (i.e., step S110), all the liquid crystal molecules in the first, second and third liquid crystal sub-units 131, 132 and 133 are converted from the vertical texture state to the planar texture state by the first preset electric field, so that the bistable liquid crystal layer 13 resumes displaying white.
Since the vertical texture state (H state) is unstable, the driving unit 16 resumes the application of the first voltage after the third voltage is applied, so that the cholesteric liquid crystal molecules in the bistable liquid crystal layer 13 are directly restored from the unstable vertical texture state (H state) to the stable planar texture state (P state), and the bistable liquid crystal layer 13 is restored to display white and to the initial state.
That is, since the H state is not a steady state, the application of the pulse voltage causes the bistable liquid crystal at the written pressed position to be rapidly changed from the FC state to the P state, and the reflectivity is restored to Rp, and at this time, the electronic whiteboard becomes an initial state, and the whole visible light can be reflected to appear white, thereby realizing the erasing function. In the erasing process, the equivalent voltage of the bistable liquid crystal layer 13 (liquid crystal cell) is changed from V w To V f Then go to V p Finally resume V w 。
In some embodiments, for the writing board structure provided with the touch component, the erasing method described above may be used, and the following erasing method may also be used, including:
step S132: in response to the received erasing command, applying a third voltage between the first sub-electrode of the first transparent electrode plate 14 and the second sub-electrode of the second transparent electrode plate 15 at the writing position to apply a third preset electric field to the bistable liquid crystal layer 13 at the writing position, so that the liquid crystal molecules in the first liquid crystal subunit 131, the second liquid crystal subunit 132 and the third liquid crystal subunit 133 at the writing position are converted into a vertical texture state (H state) under the action of the third preset electric field; wherein the third preset electric field is greater than the second preset electric field;
step S142: returning to the step of applying the first voltage between the first transparent electrode plate 14 and the second transparent electrode plate 15 (i.e., step S110), the liquid crystal molecules in the first, second and third liquid crystal subcells 131, 132 and 133 at the writing position are changed from the vertical texture state (H state) to the planar texture state (P state) by the first preset electric field, so that the bistable liquid crystal layer 13 is restored to display white.
That is, for a writing board structure provided with a touch assembly, in addition to erasing writing by means of whole-surface initialization, only the writing position may be initialized to erase writing.
The embodiment of the application also provides a writing device which comprises the liquid crystal writing board and the writing pen.
In some embodiments, the pen tip size of the writing pen is 1mm to 3mm, which is much larger than the size of the pixel unit.
The above is only a preferred embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application. Although the embodiments of the present application are disclosed above, the present application is not limited to the embodiments which are used for the convenience of understanding the present application. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is still subject to the scope of the present disclosure as defined by the appended claims.
Claims (14)
1. A liquid crystal writing board, comprising: a first transparent substrate and a light shielding substrate which are oppositely arranged, and a bistable liquid crystal layer positioned between the first transparent substrate and the light shielding substrate;
wherein, the first transparent substrate is provided with a first transparent electrode plate at one side close to the bistable liquid crystal layer;
the light shielding substrate is provided with a second transparent electrode plate at one side close to the bistable liquid crystal layer;
the bistable liquid crystal layer comprises a plurality of pixel units, each pixel unit comprises a first liquid crystal subunit, a second liquid crystal subunit and a third liquid crystal subunit which are arranged side by side along the direction parallel to the first transparent substrate, and any two adjacent liquid crystal subunits are isolated by a transparent spacer;
the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are configured to reflect red light, green light and blue light respectively under the action of a first preset electric field, and are configured to be in a scattering state under the action of a second preset electric field;
the second preset electric field is larger than the first preset electric field;
when the bistable liquid crystal layer is in the first preset electric field and one side of the first transparent substrate far away from the bistable liquid crystal layer is pressed, the electric field of the bistable liquid crystal layer at the pressing position is converted from the first preset electric field to the second preset electric field.
2. The liquid crystal tablet of claim 1 further comprising a touch assembly.
3. The liquid crystal display writing board according to claim 2, wherein the first transparent electrode plate comprises a plurality of first sub-electrodes arranged in an array;
the second transparent electrode plate comprises a plurality of second sub-electrodes which are arranged in an array.
4. The liquid crystal tablet of claim 1 wherein the color of the opaque substrate is configured as a color of writing.
5. The liquid crystal display tablet of claim 4 wherein the color of the light shielding substrate is selected from any color other than white.
6. The liquid crystal tablet of claim 1, wherein the materials of the first liquid crystal subunit, the second liquid crystal subunit, and the third liquid crystal subunit each comprise cholesteric liquid crystals.
7. The liquid crystal tablet of claim 6, wherein liquid crystal molecules within the first, second, and third liquid crystal subunits are in a planar texture state under the first preset electric field and in a focal conic texture state under the second preset electric field.
8. The liquid crystal display device of claim 1, wherein the light shielding substrate comprises a second transparent substrate and a light shielding layer disposed between the second transparent substrate and the second transparent electrode plate.
9. The liquid crystal display device of claim 8, wherein the light shielding layer is provided with a plurality of protrusions on a side near the second transparent electrode plate.
10. The liquid crystal writing board of claim 1, further comprising:
and a driving unit electrically connected to the first transparent electrode plate and the second transparent electrode plate, the driving unit being configured to apply a voltage between the first transparent electrode plate and the second transparent electrode plate to apply a corresponding electric field to the bistable liquid crystal layer.
11. A display method of a liquid crystal writing board according to any one of claims 1 to 10, comprising:
applying a first voltage between the first transparent electrode plate and the second transparent electrode plate to apply the first preset electric field to the bistable liquid crystal layer, so that the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit respectively reflect red light, green light and blue light under the action of the first preset electric field, and the bistable liquid crystal layer displays white under the action of the first preset electric field;
In response to a writing operation applied to one side of the first transparent substrate far away from the bistable liquid crystal layer, an electric field of the bistable liquid crystal layer at a writing position is converted from the first preset electric field to the second preset electric field, so that the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit at the writing position are converted into scattering states under the action of the second preset electric field, and the bistable liquid crystal layer displays the color of the shading substrate at the writing position.
12. The method of displaying a liquid crystal writing board according to claim 11, further comprising:
in response to a received erasing instruction, applying a third voltage between the first transparent electrode plate and the second transparent electrode plate to apply a third preset electric field to the bistable liquid crystal layer, so that all liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are converted into a vertical texture state under the action of the third preset electric field; wherein the third preset electric field is greater than the second preset electric field;
And returning to the step of applying a first voltage between the first transparent electrode plate and the second transparent electrode plate, so that all the liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit are converted into a plane texture state from the vertical texture state under the action of the first preset electric field, and the bistable liquid crystal layer is enabled to resume displaying white.
13. The method of displaying a liquid crystal writing board according to claim 11, further comprising:
in response to a received erasing instruction, applying a third voltage between a first sub-electrode of the first transparent electrode plate and a second sub-electrode of the second transparent electrode plate at the writing position, so as to apply a third preset electric field to the bistable liquid crystal layer at the writing position, and enabling liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit at the writing position to be converted into a vertical texture state under the action of the third preset electric field; wherein the third preset electric field is greater than the second preset electric field;
and returning to the step of applying a first voltage between the first transparent electrode plate and the second transparent electrode plate, so that the liquid crystal molecules in the first liquid crystal subunit, the second liquid crystal subunit and the third liquid crystal subunit at the writing position are converted into a plane texture state from the vertical texture state under the action of the first preset electric field, and the bistable liquid crystal layer is enabled to resume displaying white.
14. A writing device comprising a liquid crystal writing board according to any one of claims 1 to 10 and a writing pen.
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| US5847798A (en) * | 1991-05-02 | 1998-12-08 | Kent State University | Polymer stabilized black-white cholesteric reflective display |
| CN110147019A (en) * | 2018-11-30 | 2019-08-20 | 山东蓝贝思特教装集团股份有限公司 | A kind of multi-color LCD clipboard |
| CN111458945A (en) * | 2020-05-14 | 2020-07-28 | 京东方科技集团股份有限公司 | Writing device and display method thereof |
| CN112684646A (en) * | 2021-01-15 | 2021-04-20 | Tcl华星光电技术有限公司 | Writable display device, writing device, and electronic device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US8228301B2 (en) * | 2007-07-31 | 2012-07-24 | Kent Displays Incorporated | Multiple color writing tablet |
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| US5847798A (en) * | 1991-05-02 | 1998-12-08 | Kent State University | Polymer stabilized black-white cholesteric reflective display |
| CN110147019A (en) * | 2018-11-30 | 2019-08-20 | 山东蓝贝思特教装集团股份有限公司 | A kind of multi-color LCD clipboard |
| CN111458945A (en) * | 2020-05-14 | 2020-07-28 | 京东方科技集团股份有限公司 | Writing device and display method thereof |
| CN112684646A (en) * | 2021-01-15 | 2021-04-20 | Tcl华星光电技术有限公司 | Writable display device, writing device, and electronic device |
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