CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application 62/353,544, filed June 22, 2016, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to an electronic writing device, and more particularly, to a liquid crystal writing device with a thermal erase feature.

BACKGROUND

[0003] Liquid crystal technology has been widely used for electronic display devices. A liquid crystal display (LCD) is an electronically modulated optical device that takes advantages of light-modulating properties of liquid crystals. In particular, a cholesteric liquid crystal display (ChLCD) is a display device that contains a liquid crystal with a helical structure. The liquid crystal molecules are organized in layers with no positional ordering within the layers, but a director axis which varies with layers. The variation of the director axis is periodic and leads to the helical structure. The cholesteric liquid crystal is characterized by multiple stable states, e.g., focal-conic state (dark state) and planar state (bright state). The ChLCD device can be bistable and does not need power to maintain the displayed information at the focal-conic state and/or the planar state.

SUMMARY

[0004] According to at least some embodiments of the present disclosure, a liquid crystal writing device includes a first conductive layer, a second conductive layer, a cholesteric liquid crystal mixture layer sandwiched by the first conductive layer and the second conductive layer, and a top substrate layer. The top substrate layer receives an external pressure applied to the top substrate layer and relays at least a portion of the external pressure to a second portion of the cholesteric liquid crystal mixture layer. The second portion of the cholesteric liquid crystal mixture layer may switch from a light scattering state to a light reflective state in response to the portion of the external pressure. At least a second portion of the cholesteric liquid crystal mixture layer may switch from the light reflective state to the light scattering state in response to that a temperature of the second portion exceeds a clearing point of the cholesteric liquid crystal mixture layer.

[0005] According to at least some embodiments of the present disclosure, a system for partially erasing a displayed content includes a cholesteric liquid crystal mixture layer, a top substrate layer, and a thermal eraser. The cholesteric liquid crystal mixture layer may switch between a light scattering state and a light reflective state. The top substrate layer may relay at least a portion of an external pressure to a first portion of the cholesteric liquid crystal mixture layer to switch the first portion from a light scattering state to a light reflective state for displaying a content. The thermal eraser may contact a target area of the top substrate layer and increase a temperature of a second portion of the cholesteric liquid crystal mixture layer to switch the second portion from the light reflective state to the light scattering state for erasing at least a portion of the content.

[0006] According to at least some embodiments of the present disclosure, a method for partially erasing a displayed content, comprising: receiving, by a top substrate layer, an external pressure; relaying at least a portion of the external pressure to the a first portion of a cholesteric liquid crystal mixture layer to switch the first portion from a light scattering state to a light reflective state; receiving a heat, from a thermal eraser applied on a target area of the top substrate layer, by a second portion of the cholesteric liquid crystal mixture layer that is adjacent to the target area; and switching the second portion of the cholesteric liquid crystal mixture layer from the light reflective state to the light scattering state in response to that a temperature of the second portion of the cholesteric liquid crystal mixture layer exceeds a clearing point.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Aspects of some embodiments of the present disclosure are best understood from the following detailed description when read with the accompanying figures. It is noted that various structures may not be drawn to scale, and dimensions of the various structures may be arbitrarily increased or reduced for clarity of discussion.

[0008] FIG. 1 illustrates an example of a liquid crystal writing device having a selective partial erase feature, in accordance with some embodiments of the present disclosure.

[0009] FIG. 2A illustrates a cross-sectional view of an example of a liquid crystal writing device, in accordance with some embodiments of the present disclosure. [0010] FIG. 2B illustrates a cross-sectional view of an example of a liquid crystal writing device including a thermal eraser, in accordance with some embodiments of the present disclosure.

[0011] FIG. 2C illustrates an example of a thermal eraser including heating wires, in accordance with some embodiments of the present disclosure.

[0012] FIG. 2D illustrates an example of a charger and a thermal eraser, in accordance with some embodiments of the present disclosure.

[0013] FIG. 2E illustrates an example of a thermal eraser including a ceramic heating element, in accordance with some embodiments of the present disclosure.

[0014] FIG. 2F illustrates an example of a charger and a thermal eraser, in accordance with some embodiments of the present disclosure.

[0015] FIG. 3 illustrates an exploded view of a liquid writing device including IR components, in accordance with some embodiments of the present disclosure.

[0016] FIG. 4 illustrates various components of a liquid crystal writing device having a display feature and information flows among the components, in accordance with some embodiments of the present disclosure.

[0017] FIG. 5A illustrates a teleconference system including one or more liquid crystal display devices, in accordance with some embodiments of the present disclosure.

[0018] FIG. 5B illustrates a teleconference system including one or more liquid crystal display devices and one or more regular TV displays, in accordance with some embodiments of the present disclosure.

[0019] FIG. 6 illustrates a blackboard system including one or more liquid crystal display devices.

[0020] Common reference numerals are used throughout the drawings and the detailed description to indicate the same or similar components. The present disclosure can be best understood from the following detailed description taken in conjunction with the accompanying drawings. DETAILED DESCRIPTION

[0021] The aforementioned illustrations and following detailed descriptions are exemplary for the purpose of further explaining the scope of the instant disclosure. Other objectives and advantages related to the instant disclosure will be illustrated in the subsequent descriptions and appended drawings.

[0022] According to at least some embodiments of the present disclosure describe a liquid crystal (LC) display device, such as a liquid crystal writing device. The liquid crystal writing device can have various functionalities such as selective partial erase, save and display. At least in some embodiments, the LC display device can be, e.g., a bistable LC display device with a lower power consumption. After the display content is shown in the device, the bitable LC display device does not need voltage or electric power to maintain the displayed content until the device switches to show a new display content. To achieve the bistability, the LC display device may include, e.g., a cholesteric liquid crystal mixing (e.g., with or without a polymer). For example, U.S. Patent No. 6,104,448 (which is incorporated herein by reference in its entirety) discloses a cholesteric liquid crystal mixture with bistability.

[0023] The cholesteric liquid crystal mixture can switches between, e.g., a light scattering focal-conic texture (or state) and a light reflective planar texture (or state). The mixture include chiral dopants and liquid crystals. The chiral dopants of the cholesteric liquid crystal mixture have a pitch length, which corresponds to the wavelength of light being reflected. The wavelength may be, e.g., within the visible spectrum. The polymer network of the cholesteric liquid crystal mixture can be distributed uniformly, with liquid crystal domains distributed in the polymer network.

[0024] The LC display device may include a background layer to create a high contrast writing space. For example, the LC display device may include a dark layer (e.g., black ink) coated onto a bottom surface of the substrate of the device. Alternatively, the material of the substrate may be or include, e.g., Polyethylene Terephthalate (PET), which can be flexible and dark (e.g., black).

[0025] An application of a mechanical stress from an object tip (e.g., a finger or a stylus) through a surface of the device to the cholesteric liquid crystal may switch the cholesteric liquid crystal from a light scattering focal conic state to a light reflective planar state. As a result, the cholesteric liquid crystal display device shows a trace of a light reflective area following the places where the object tip touches the surface of the device. Therefore, the device can function as an electronic writing device. In some embodiments, the cholesteric liquid crystal device may include two conductive layers disposed on and below the layer of the cholesteric liquid crystal mixture respectively. In other words, the cholesteric liquid crystal mixture layer is sandwiched by the conductive layers. An electrical pulse with a voltage above a threshold can be applied to conductive layers. The electrical pulse applied to the conductive layers returns the cholesteric liquid crystal mixture from the reflective planar state back to the light scattering focal-conic state. Thus, the entire displayed content is erased.

[0026] In some embodiments, the LC display device may be, e.g., a high brightness liquid crystal writing device (e.g., a board or a tablet). For example, Wicue Inc. manufactures a high brightness liquid crystal writing tablet called Wicue® blackboard. The tablet can have a size of, e.g., 1.2 meter by 4 meters, and can have a brightness higher than ones of other writing devices on the market that are based on cholesteric liquid crystal or other types of liquid crystal. In some embodiments, the device may be manufactured using an effective, low-cost roll-to-roll method. The roll-to-roll method produces a reliable, healthy (to human bodies such as eyes) LC writing film that has a suitable uniformity and a large width. The LC writing devices such as the Wicue® blackboard may be utilized as a replacement of the blackboards or whiteboards in classrooms, conference rooms and other places. Such a large writing device is eco-friendly since there is no chalk dust for the blackboard or costly dry erase markers for the whiteboard. In some other embodiments, the writing device can be used as, e.g., a personal tablet or personal writing board.

[0027] In some embodiments, the LC device may achieve a higher brightness because the liquid crystal mixture does not contain polymers. In other words, the polymer may reduce the reflectivity of the cholesteric liquid crystal at its light reflective planar state, because the surface anchoring of the polymer domains aligns the helix structure of the cholesteric liquid crystal into different orientations. The LC device according to some embodiments avoids the negative effects of the polymer and achieves an efficient roll-to-roll production of large size cholesteric liquid crystal films.

[0028] According to at least some embodiments of the present disclosure, a disclosed liquid crystal writing device not only can erase the entire display area of the device, but also can selectively erase a portion of the display area. Such a selective partial erase feature is desirable because a user may want to make changes to the content written on the device (e.g., fixing an error or making an adjustment). The user can select a portion of the written content to be erased, without affecting the remaining portion of the written content. For example, FIG. 1 illustrates an example of a liquid crystal writing device having a selective partial erase feature. The user has written a content (e.g., "How to make Wicue Board partial erase") on the liquid crystal writing device 100. In order to erase, e.g., the letter "m," the user (using an electronic eraser such as thermal eraser or a finger) to identify an area 110 enclosing the letter "m" (by, e.g., clicking or drawing a circle or square). In response, the liquid crystal writing device 100 can erase the content inside of the selected area 110, which maintaining the displayed content in the remaining portion of the display unchanged.

[0029] In some embodiments, the liquid crystal writing device can include a recording (or save) feature. Using an interface included in the liquid crystal writing device, a user can save the written and/or displayed content into digital data. For example, the device may save the written and/or displayed content into digital files, such as files in PDF (portable document format) or JPEG (joint photographic experts group) formats. The digital data may be stored in a memory (either an internal memory of the device or a removable memory card or device), or transmitted to an external device (via, e.g., wired or wireless network).

[0030] In some embodiments, the liquid crystal writing device can include a display feature. That is, other than showing the content being written on the device, the device can further display other digital contents. For example the liquid crystal writing device can also read digital data from a memory (either an internal memory of the device or a removable memory card or device), or receive digital data from an external device (via, e.g., wired or wireless network). The device converts the retrieved digital data into display information and display the content of the retrieved digital data on the display component of the device. The digital data may include content that was written on the device and saved by the device. For example, a user can write some content on the device and save the content into a digital file. Later the user can instruct the device to load the saved digital file and display the content on the device for, e.g., discussion or further editing.

[0031] In some embodiments, the liquid crystal writing device can simultaneously display content being written on the surface of the device as well as content being retrieved from a memory or externally via a network. Furthermore, multiple liquid crystal writing devices can synchronize the content being written and/or displayed. For example, by remotely deploying two or more liquid crystal writing devices as disclosed, users in different locations can work jointly on the same written content. Each liquid crystal writing device can retrieve digital data of the content being written on other devices and display the content of the retrieved digital data on the device together with the content being written on the device itself. Therefore, the content being displayed on the devices are synchronized, and each device shows contents being written by users from different locations. Based on the written contents synchronized at the devices, the users can work together even from different locations.

[0032] Liquid Crystal Writing Device

[0033] FIG. 2A illustrates a cross-sectional view of an example of a liquid crystal writing device, according to at least some embodiments of the present disclosure. The liquid crystal writing device 200 includes a first substrate layer 210, a first conductive layer 220, a liquid crystal mixture layer 230 (also referred to as cholesteric liquid crystal film or mixture), a second conductive layer 240, a second substrate layer 250 and a base layer 260. The first substrate layer 210 may function as a hand-writing layer such that a user can use objects (e.g., stylus or finger) to apply mechanical pressure on various locations of the hand-writing layer.

[0034] The liquid crystal mixture layer 230 is sandwiched by the first and second conductive layers 220 and 240. The device 200 may supply an electric pulse to the first and second conductive layers 220 and 240 such that the first and second conductive layers 220 and 240 create an electric field with a voltage across the liquid crystal mixture layer 230.

[0035] The liquid crystal mixture layer 230 may include cholesteric liquid crystals 231 and chiral dopant 232. The concentration of the chiral dopants may be, e.g., from about 0.1 to about 80, from about 0.5 to about 40, or from about 0.5 to about 27% weight percent of a combined weight of the chiral dopants and the liquid crystals. The chiral dopant 232 may control the reflective color and/or brightness of the cholesteric liquid crystals 231.

[0036] The second substrate layer 250 functions as a background layer to create a high contrast writing space. For example, the second substrate layer 250 may include a dark layer (e.g., black ink) coated onto a top or bottom surface of a transparent layer. Alternatively, the material of the substrate may be or include, e.g., Polyethylene Terephthalate (PET), which can be flexible and dark (e.g., black).

[0037] As shown in FIG. 2A, when a user writes (using, e.g., a writing device 290) on a top surface of the first substrate layer 210, a mechanical pressure is applied through the first substrate layer 210 and the first conductive layer 220 to the liquid crystal mixture 230. The mechanical stress can cause at least some of the cholesteric liquid crystals 231 to change the molecular orientations with a lower energy state. As a result, a portion of cholesteric liquid crystals 231 being pressured switches from a focal-conic (FC) scattering state (dark state) to a planar (P) color reflective state (bright state). Thus, corresponding to a trace written by the writing device 290, the portion of the cholesteric liquid crystals 231 being pressured presents a bright color, in contrast with the background color.

[0038] In some embodiments, the cholesteric liquid crystals 230 at the planar reflective state reflect ambient light. In other words, the color and/or brightness of the reflective writing trace may depend on the color and/or brightness of the ambient light. The writing device 290 may be made of, e.g., PET and may include a felt or other material at the tip of the writing device 290 to mimic a feel of, e.g., a regular pen or a dry erase marker.

[0039] In some embodiments, the background color of the writing device 200 may depend on the color of the base layer 260. The color of the base layer 260 may be chosen based on the actual needs of the applications. In some embodiments, the base layer 260 may be in black and the reflective writing color may be green or yellow at a normal viewing angle to optimize the writing contrast and the brightness at various viewing angles. In some embodiments, when the reflective writing color at the normal viewing angle is set to yellow, the reflective writing color at an oblique viewing angle may be green, which is still sensible to human eyes. If the reflective writing color is set to green at the normal viewing angle, the reflective writing color at the oblique viewing angle may be blue, which may not be sensible enough to human eyes, due to the color dependence of human eye sensitivity.

[0040] To acheive the selective partial erase feature, a thermal eraser 270 (also referred to as heated brush) can be applied to the top surface of the first substrate layer 210. FIG. 2B illustrates a cross-sectional view of an example of a liquid crystal writing device including a thermal eraser, according to at least some embodiments of the present disclosure. The thermal eraser 270 functions as a heat source and heats the portion of the liquid crystal mixture 230 adjacent to a target area that is below the thermal eraser 270.

[0041] The cholesteric liquid crystal mixture 230 at the target area is heated to a temperature above a clearing point of the cholesteric liquid crystal mixture 230. As a result, the cholesteric liquid crystal mixture 230 at the target area is switched to the focal-conic (FC) scattering state and is no longer reflective. After the thermal eraser 270 moves away from the target area or moves away from the first substrate layer 210, the cholesteric liquid crystal mixture 230 at the target area remains at the focal-conic (FC) scattering state, even when the temperature of the cholesteric liquid crystal mixture 230 drops back to the room temperature. Thus, the writing trace at the target area is selectively erased. In some embodiments, the clearing point may be, from about 10 degrees to about 70 degrees, from about 30 degrees to about 50 degrees, or from about 30 degrees to about 40 degrees.

[0042] In some embodiments, the device 200 can conduct a full erase by applying an electrical voltage above a threshold to the entire liquid crystal mixture layer 230 via the first and second conductive layers 220 and 240. As a result, the entire liquid crystal mixture layer 230 is switched back to the focal-conic (FC) scattering state. The entire display area of the device 200 is erased and shows the background color.

[0043] Thermal Eraser and Charger

[0044] FIG. 2C illustrates an example of a thermal eraser, according to at least some embodiments of the present disclosure. The thermal eraser 270 may include a soft erasing part 272 and a holder 273. The soft erasing part 272 is designed to touch the top surface of the first substrate layer 210 of the liquid crystal writing device 200 when a user holds the holder 273 to apply the thermal eraser 270 to the writing device 200.

[0045] The thermal eraser 270 may include heating wires 274 (also referred to as resistance wires) to supply the heat. The heating wires 274 may be powered by an external power source via a wire, or powered by an internal battery (not shown) so that the thermal eraser can be used in a wireless manner. The thermal eraser 270 may further include a charging contact 275. The charging contact 275 is designed to electrically couple to a charger in order to charge the internal battery of the thermal eraser 270. In some embodiments, the size of the thermal eraser 270 may be a palm size. In some embodiments, the size and the shape of the thermal eraser 270 may be different depending on the size and the shape of the liquid crystal writing device 200. In some embodiment, the thermal erasure 270 have a small size and shape (e.g., like a pencil) to erase content of a small area.

[0046] FIG. 2D illustrates an example of a charger and a thermal eraser, according to at least some embodiments of the present disclosure. The charger 280 includes a wire 282, a holder 284, and a charging port 286. A user can place the thermal eraser 270 in the charger 280. The holder 284 of the charger 280 accommodates at least a portion of the thermal eraser 270 and secures the thermal eraser 270. When the thermal eraser 270 is secured, the charging port 286 of the charger 280 is electrically coupled to the charging contact 275 of the thermal eraser 270 for charging the internal battery of the thermal eraser 270. The wire 282 relays an electrical power from an external power source to the charging port 286.

[0047] In some embodiments, the thermal eraser can include one or more heating elements other than the heating wires. FIG. 2E illustrates an example of a thermal eraser, according to at least some embodiments of the present disclosure. The thermal eraser 270A may include a soft erasing part 272 A and a holder 273 A. The soft erasing part 272 A is designed to touch the top surface of the first substrate layer 210 of the liquid crystal writing device 200 when a user holds the holder 273 A to apply the thermal eraser 270A to the writing device 200.

[0048] The thermal eraser 270A may include a ceramic heating element 274A (e.g., a positive temperature coefficient (PTC) ceramic) to supply the heat. The ceramic heating element 274A may be powered by an external power source via a wire, or powered by an internal battery (not shown) so that the thermal eraser can be used in a wireless manner. Alternatively, the ceramic heating element 274A may receive electrical current from a charger via a charging pad 275 A.

[0049] FIG. 2F illustrates an example of a charger and a thermal eraser, according to at least some embodiments of the present disclosure. The charger 280A includes a wire 282A, a holder 284A, and a charging port 286A. A user can place the thermal eraser 270A in the charger 280A. The holder 284A of the charger 280A accommodates at least a portion of the thermal eraser 270A and secures the thermal eraser 270A. When the thermal eraser 270A is secured, the charging port 286A of the charger 280A is electrically coupled to the charging contact 275A of the thermal eraser 270A for supplying an electrical current to the ceramic heating element 274A. The wire 282A relays an electrical power from an external power source to the charging port 286A. The charger 280A may further include a switch 288A (or a button). A user can use the switch 288A to control the operation status (e.g., on and off) of the charger 280A under which the charger 280A supplies the electrical current to the ceramic heating element 274A or not.

[0050] In some embodiments, when the thermal eraser 270A is inserted in the charger 280A, the ceramic heating element 274A receives the electrical current via the charging contact 275A and the charging port 286A, and heats up to a design temperature. A user can retrieve the thermal eraser 270A from the charger 280A and apply the thermal eraser 270A to a target area of the top surface of the first substrate layer 210 of the liquid crystal writing device 200. The ceramic heating element 274 provides the heat to the cholesteric liquid crystal mixture 230 adjacent to the target area. The cholesteric liquid crystal mixture 230 adjacent to the target area is heated to a temperature above a clearing point of the cholesteric liquid crystal mixture 230. As a result, the cholesteric liquid crystal mixture 230 at the target area is switched to the focal-conic (FC) scattering state and the displayed content at the target area is erased.

[0051] Infrared (IR) Solution

[0052] According to some embodiments of the present disclosure, the liquid crystal writing device can further include touch sensing component such as infrared (IR) components to recognize touch motions (e.g., finger touching the writing surface of the device). The touch motions may be identified as inputs for writing and/or for selective partial erasing. The identified touch motions may be saved into, e.g., an internal memory, a memory card or device, or an external device. The touch sensing component may be, e.g., an infrared (IR) touch sensing component, a resistive touch sensing component, a capacitive touch sensing component, or an electromagnetic resonance (EMR) touch sensing component.

[0053] FIG. 3 illustrates an exploded view of a liquid writing device including IR components, according to at least some embodiments of the present disclosure. The liquid writing device 300 includes a front cover 310, an IR touch panel 320, a liquid crystal (LC) writing film 330 and a writing bench 340.

[0054] The IR touch panel 320 includes IR transmitters and corresponding IR receivers. The IR receivers detect the IR signals emitted by the corresponding IR transmitters. When an object (e.g., a finger) is placed in proximity to the front cover 310, some IR signals may be reflected or absorbed by the object. The IR receivers detect the differences of the IR signals and accordingly identify the location of the object (e.g., the location on the front cover 310 being touched by the object). The locations may be saved as the traces of content being displayed.

[0055] The LC writing film 330 can include cholesteric liquid crystal mixture, conductive layers, and/or substrate layers similar to the components of the liquid crystal writing device 200. The LC writing film 300 may further include horizontal and vertical conductive lines such as 301, 302, 303 and 304. By feeding an electrical pulse to a combination of a horizontal conductive line and a vertical conductive line. The device 300 can change the liquid crystal status at the location where the horizontal conductive line and the vertical conductive line crosses. For example, in response to the electrical pulse, the cholesteric liquid crystal mixture at the crossed location may switch from the focal-conic (FC) scattering state to the planar (P) reflective state, or vice versa. [0056] Display Feature

[0057] FIG. 4 illustrates various components of a liquid crystal writing device having a display feature and information flows among the components. Herein the term "display feature" (or display function) refers to a feature that the liquid crystal writing device can display additional contents besides the content being written on the device. For example, the liquid crystal writing device may retrieve digital data of the drawings from an internal memory or from an external device. The communication unit 404 of the liquid crystal writing device may connect to an external mobile device 405 (e.g., a mobile phone or a tablet) via a wireless network (e.g., Wi-Fi or Bluetooth). The communication unit 404 retrieves the digital data the internal memory or from the external mobile device 405 and sends the data to the control display unit 402. The control display unit converts the digital data into presentable content and forwards the content to be displayed to the writing display unit 406 of the liquid crystal writing device. In other words, the liquid crystal writing device may function as an external display for the mobile device 405. Alternatively, the mobile device 405 may also function as an external display of the liquid crystal writing device.

[0058] The power supply unit 403 is configured to supply power to the components of the liquid crystal writing device. The touch sensor unit 401 may detect touch motions as inputs to the liquid crystal writing device for writing, erasing, or other operations.

[0059] The liquid crystal writing device may display contents (e.g., written contents or other retrieved contents) using various display addressing methods. For example, the liquid crystal writing device may use a direct drive method. According to the direct drive method, the display area is divided into multiple segments. The smallest controllable component for the image production is a segment instead of pixel. Each segment is directly connected and controlled individually by peripheral electronics. The segments are arranged in such way so that they can produce desired patterns. For example, a 7-segments arrangement can be used for displaying simple alphanumerical information and may have applications such as calculators and watches. The direct drive method does not use multiplexing can be used in low information content applications.

[0060] The liquid crystal writing device may also use a multiplexing method. The display area is organized as a pixel matrix with M rows and N columns. Each pixel is controlled individually and but via a multiplexing addressing approach. For example, the multiplexing addressing method may be, e.g., a passive matrix (PM) method.

[0061] The passive matrix is a one-line-at-a-time driving method. During a programming time, a pulse from a row peripheral driver activates all the pixels of the programming line and at the same time the data voltage is delivered to the storage capacitor and the liquid crystal through a peripheral column driver. Passive matrix is a addressing method with a relatively low number of interconnections. For example, for an M rows and N columns array, the direct drive method may needs MxN interconnections, while the passive matrix method may need M+N interconnections. Furthermore, passive matrix is simple and cost-efficient.

[0062] Teleconference Mode

[0063] According to at least some embodiments of the present disclosure, one or more liquid crystal display devices as disclosed may be part of a teleconference system. FIG. 5A illustrates a teleconference system including one or more liquid crystal display devices. For example, as shown in FIG. 5 A, the teleconference system 500A includes a liquid crystal writing device 501 deployed in a first location (e.g., London) and a liquid crystal writing device 502 deployed in a second location (e.g., New York). The liquid crystal writing device 501 and the liquid crystal writing device 502 are interconnected via a network (e.g., the Internet).

[0064] As shown in FIG. 5 A, the liquid crystal writing device 501 is deployed in a conference room in, e.g., London, wherein one or more participants are in front of the liquid crystal writing device 501. The liquid crystal writing device 502 is deployed in another conference room in, e.g., New York, wherein one or more participants are in front of the liquid crystal writing device 502. Both liquid crystal writing devices 501 and 502 may include features such as selective erase, save, and/or display. For example, a presenter (e.g., a participant) in London can write information "A" on the liquid crystal writing device 501. The liquid crystal writing device 502 receives the information about "A" and displays the information "A" in a synchronized manner. Similarly, the presenter in London can write information "B" on the liquid crystal writing device 502. The liquid crystal writing device 501 receives the information about "B" and displays the information "A" in a synchronized manner.

[0065] Either device 501 or device 502 (or both) can save the displayed content to, e.g., an internal memory, a removable memory card or drive, or an external device. The selective erase feature can also be synchronized. For example, if a participant erases the information "B" from the liquid crystal writing device 501 (using, e.g., a thermal eraser 270 or 270A). The liquid crystal writing device 502 receives information about the erasure of "B" from device 501. In response, the liquid crystal writing device 502 may also erase the information "B" from the device 502 itself in a synchronized manner. In some embodiments, to achieve the synchronized erasure, the liquid crystal writing device 502 saves the entire current displayed content before the erasure of "B" in an internal memory. The device 502 then processes the image in the internal memory to remove the target area containing "B." Then the device 502 erases the entire current displayed content and displays the processed image without "B" from the internal memory.

[0066] In some embodiments, a liquid crystal writing device (e.g., 501) can remotely control another liquid crystal writing device (502) during a teleconference. For example, a user can write a content on the liquid crystal writing device 501 and instructs the device 501 to send the written content along with an instruction to the liquid crystal writing device 502. The liquid crystal writing device 502 receives the written content and the instruction. According to the instruction, the liquid crystal writing device 502 displays the written content. Furthermore, the user can modify the written content on the device 501 and instruct the device 502 to follow the modifications remotely.

[0067] In some embodiments, the liquid crystal writing devices can be used together with other display devices (e.g., regular TV displays). FIG. 5B illustrates a teleconference system including one or more liquid crystal display devices and one or more regular TV displays. The teleconference system 500B of FIG. 5B is similar to the teleconference system 500A of FIG. 5 A, except that the teleconference system 500B further includes an LCD (liquid crystal display) TV 503 and a LCD TV 504. The LCD TVs 503 and 504 can also be part of the synchronized displays. For example, the information "A" written on the liquid crystal writing device 501 may be synchronized on the LCD TV 504, instead of the liquid crystal writing device 502. The information "B" written on the liquid crystal writing device 501 may be synchronized on the LCD TV 504, instead of the liquid crystal writing device 502.

[0068] Liquid Crystal Writing Blackboard System

[0069] According to at least some embodiments of the present disclosure, a liquid crystal writing blackboard system can include multiple liquid crystal writing devices as disclosed. FIG. 6 illustrates a blackboard system including one or more liquid crystal display devices. As shown in FIG. 6, the blackboard system 600 includes a frame 602, liquid crystal writing devices 601 and 604, and a smart LED TV 603. The frame 602 (e.g., a metal frame) reliably supports, encloses and secures the liquid crystal writing devices 601 and 604 and the smart LED TV 603. The frame 602 may include sliding mechanism(s) such that the liquid crystal writing devices 601 and 604 can slide freely within the frame 602 in a horizontal direction (e.g., from left to right, or from right to left).

[0070] Although the blackboard system 600 includes two liquid crystal writing devices, it is to be understood that a blackboard system can include any number of liquid crystal writing devices as disclosed and the sizes of the liquid crystal writing devices can vary. The smart LCD TV 603 may be disposed in the middle of the frame 602. The smart LCD TV 603 can be disposed behind the sliding mechanism(s) such that the liquid crystal writing devices 601 and/or 604 can be slided to positions wherein at least a portion of the smart LCD TV 603 is covered by the liquid crystal writing devices 601 and/or 604.

[0071] The liquid crystal writing devices 601 and 604 can be, e.g., the liquid crystal writing device 200 as disclosed. For example, the liquid crystal writing devices 601 and 604 can have features of selective partial erase, save, and/or display. For example, in some embodiments, users can write on the liquid crystal writing devices 601 and 604. The written content can be saved into, e.g., an internal memory or a removable memory card or device of the blackboard system 600. The users can also use the selective partial erase feature to erase any content being written on the liquid crystal writing devices 601 and/or 604. In some embodiments, the smart LCD TV 603 can be used to display additional contents that are not written on the devices 601 and 604.

[0072] In the description of some embodiments, a component provided "on" or "above" or "on top of another component can encompass cases where the former component is directly on (e.g., in physical contact with) the latter component, as well as cases where one or more intervening components are located between the former component and the latter component.

[0073] Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It can be understood that such range formats are used for convenience and brevity, and should be understood flexibly to include not only numerical values explicitly specified as limits of a range, but also all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified.

[0074] As used herein, the terms "approximately," "substantially," "substantial" and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. For example, when used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ±10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%), less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%.

[0075] While the present disclosure has been described and illustrated with reference to specific embodiments thereof, these descriptions and illustrations do not limit the present disclosure. It will be clearly understood by those skilled in the art that various changes may be made, and equivalents may be substituted within the embodiments without departing from the true spirit and scope of the present disclosure as defined by the appended claims. The illustrations may not necessarily be drawn to scale. There may be distinctions between the artistic renditions in the present disclosure and the actual apparatus, due to variables in manufacturing processes and such. There may be other embodiments of the present disclosure which are not specifically illustrated. The specification and drawings are to be regarded as illustrative rather than restrictive. Modifications may be made to adapt a particular situation, material, composition of matter, method, or process to the objective, spirit and scope of the present disclosure. All such modifications are intended to be within the scope of the claims appended hereto. While the methods disclosed herein have been described with reference to particular operations performed in a particular order, it should be understood that these operations may be combined, sub-divided, or re-ordered to form an equivalent method without departing from the teachings of the present disclosure. Therefore, unless specifically indicated herein, the order and grouping of the operations are not limitations of the present disclosure.