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EP-3990981-B1 - LIQUID CRYSTAL DIMMABLE FILM

EP3990981B1EP 3990981 B1EP3990981 B1EP 3990981B1EP-3990981-B1

Inventors

  • LI, FENGHUA

Dates

Publication Date
20260506
Application Date
20200624

Claims (20)

  1. An apparatus including a liquid crystal cell, the liquid crystal cell comprising: a first substrate (202); a second substrate (204); first spacers (402) and second spacers (208) sandwiched between the first substrate and the second substrate to define a cell gap between the first substrate and the second substrate, the first spacers being fixedly bonded to each of the first substrate and the second substrate, the second spacers being movable between the first and second substrates, wherein the first spacers and the second spacers are configured to maintain the cell gap between the first substrate and the second substrate; a sealant (206) sandwiched between the first substrate and the second substrate and enclosing the first spacers and the second spacers; and a liquid crystal (214) enclosed by the sealant, the first substrate, and the second substrate, wherein the first spacers and the second spacers include at least one of silica gel balls or plastic balls.
  2. The apparatus of claim 1, wherein the first spacers include resin (404) to provide fixed bonding between the at least one of silica gel balls or plastic balls with each of the first substrate and the second substrate.
  3. The apparatus of claim 2, wherein the first spacers are formed by printing a mixture of the silica gel balls and the resin on the first substrate via at least one of a screen or a stencil.
  4. The apparatus of any of claims 2-3, wherein the second spacers include an adhesive to provide bonding between the silica gel balls with each of the first substrate and the second substrate.
  5. The apparatus of any of claims 1-4, wherein each of the first substrate and the second substrate comprises a flexible material, the flexible material comprising at least one of: glass, polycarbonate (PC), polyethylene terephthalate (PET), or cellulose triacetate (TAC).
  6. The apparatus of any of claims 1-5, wherein each of the first substrate and the second substrate includes a Polyamide (PI) coating (204, 210) having a rubbing pattern to align molecules of the liquid crystal.
  7. The apparatus of claim 6, wherein the PI coating of the first substrate and the PI coating of the second substrate have anti-parallel rubbing directions; and wherein the liquid crystal comprises a guest-host(GH) liquid crystal, further optionally wherein the GH liquid crystal cells comprise dye molecules; and wherein a color of the dye molecules is configured to set a color of light transmitted through at least one of the first substrate or the second substrate.
  8. The apparatus of claim 6, wherein the PI coating of the first substrate and the PI coating of the second substrate have perpendicular rubbing directions; and wherein the liquid crystal comprises a twist-nematic(TN) liquid crystal, optionally further comprising a first polarizer film and a second polarizer film sandwiching the liquid crystal.
  9. The apparatus of any of claims 1-8, further comprising: a dimmable liquid crystal film including: a first glass layer (302); a first interlayer(304); the liquid crystal cell; a second interlayer(306); and a second glass layer(308), wherein: the first interlayer is configured to hold fragments of the first glass layer together when the first glass layer is shattered; the second interlayer is configured to hold fragments of the second glass layer together when shattered; and the liquid crystal cell is sandwiched between the first glass layer and the second glass layer and bonded to a first surface of the first glass layer via the first interlayer and bonded to a second surface of the second glass layer via the second interlayer.
  10. The apparatus of claim 9, wherein the first interlayer and the second interlayer comprise at least one of: PVB, EVA, or TPU.
  11. The apparatus of claim 9, wherein the first interlayer and the second interlayer are configured as an ultraviolet light blocking layer.
  12. The apparatus of any of claims 9 and 11, wherein each of the first glass layer and the second glass layer has a curved surface; and wherein the first substrate and the second substrate are bent to conform with the curved surfaces of the first glass layer and the second glass layer.
  13. The apparatus of any of claims 9 and 11-12, wherein at least one of the first substrate, the second substrate, the first glass layer, or the second glass layer is coated with an infra-red blocking layer.
  14. The apparatus of any of claims 9 and 11-13, further comprising: an infra-red film(512,518); a third interlayer(514); and a fourth interlayer(516); wherein the infra-red film is sandwiched between the first glass layer and the liquid crystal film, or between the liquid crystal film and the second glass layer; and wherein the infra-red film is bonded to the first glass layer and the liquid crystal film, or to the liquid crystal film and to the second glass layer, via respectively a third interlayer and a fourth interlayer.
  15. The apparatus of claim 14, wherein the third interlayer and the fourth interlayer comprise at least one of polyvinyl butyral (PVB), ethylene-vinyl acetate (EVA), or polyurethane (TPU).
  16. The apparatus of any of claims 9 and 11-15, further comprising a privacy glass (600) having two discrete levels of light transmittance attached to the dimmable liquid crystal film, wherein the apparatus is configured to: in a first mode, set the light transmittance of the privacy glass to a maximum level and set a light transmittance of the dimmable liquid crystal film to a pre-determined level; and in a second mode, set the light transmittance of the privacy glass to a minimum level.
  17. The apparatus of claim 16, further comprising: a light sensor; and driver circuits, wherein the light sensor is configured to generate sensor data representing a measurement of an ambient light intensity; and wherein the driver circuits are configured to generate, based on the sensor data, signals to generate an electric field across the liquid crystal cell to adjust the light transmittance of the dimmable liquid crystal film based on the ambient light intensity.
  18. A method, comprising: forming a sealant (206) at first pre-determined locations on at least one of a first substrate (202) or a second substrate (204) to define a base area of a liquid crystal cell; forming mixtures including resin (404) and first spacers (402) at second pre-determined locations of a first area of the first substrate corresponding to the base area of the liquid crystal cell; spraying a solution containing second spacers (208) over a second area on the second substrate corresponding to the base area of the liquid crystal cell, wherein the first spacers and the second spacers are configured to maintain a cell gap between the first substrate and the second substrate; orienting the first substrate and the second substrate to enable the first spacers to join the first substrate via the resin and to enable the second spacers to join the second substrate; filling liquid crystal (214) into a cell space defined by the sealant, the first substrate, and the second substrate; and performing a curing process to harden the sealant and to form fixed bonding between the first spacers and each of the first substrate and the second substrate via the resin, wherein the first spacers and the second spacers include at least one of silica gel balls or plastic balls.
  19. The method of claim 18, wherein filling liquid crystal into the cell space comprises: dispensing the liquid crystal into the cell space between the first substrate and the second substrate; and pressing the first substrate and the second substrate against the liquid crystal, wherein the curing process is performed after the pressing, optionally wherein the curing process comprises at least one of: an ultra-violet curing and a thermal curing process.
  20. The method of claim 19, further comprising: controlling a first pair of rollers (802) to unroll a first roll of substrate (804) comprising the first substrate; and controlling a second pair of rollers (812) to unroll a second roll of substrate (814) comprising the second substrate, wherein the pressing of the first substrate and the second substrate against the liquid crystal is performed based on moving the first substrate and the second substrate through a gap between a first roller of the first pair of rollers and a second roller of the second pair of rollers; and wherein the dispensing of the liquid crystal into the cell pace between the first substrate and the second substrate is performed when at least a part of the first substrate and at least a part of the second substrate are in the gap between the first roller and the second roller.

Description

RELATED APPLICATION This patent application claims priority to U.S. Non-Provisional Patent Application Ser. No. 16/455,495, filed June 27, 2019, entitled "Liquid Crystal Dimmable Film," which is assigned to the assignee hereof. BACKGROUND The disclosure relates generally to a dimmable film, and, more specifically, to a dimmable film based on liquid-crystal technology. Dimmable film generally refers to a film having a variable light transmittance. One example of dimmable film is dimmable glass, which can be used to control an intensity of light entering or exiting from a structure. There are many applications for a dimmable glass. For example, a dimmable glass can be used to form a window of an automobile, an aircraft, etc. The light transmittance can be reduced to, for example, protect the passengers from high energy light in a bright environment. The light transmittance can also be increased to, for example, provide the passengers with improved visibility in a dim environment. As another example, a dimmable glass can be used as part of architecture glass of a building. The dimmable glass can perform the function of a blind to, for example, adjust the intensity of light entering a building, to protect privacy, etc. Besides variable light transmittance, a dimmable glass may have various other desired properties. For example, it is desirable to increase the achievable maximum light transmittance of a dimmable glass, and to have a short response time to allow fast adjustment of the light transmittance, to provide improved visibility to a user (e.g., a driver in an automobile) under various operation conditions. Moreover, it is also desirable for the dimmable glass to have high strength and to hold together when shattered to improve safety. US2001013920A1 discloses an apparatus for manufacturing a liquid crystal light modulating device including a first substrate and a second substrate, at least one of which is flexible, and a liquid crystal layer filled between the first and second substrates, said apparatus comprising: a support on which the first substrate is to be located; a dispenser which dispenses a liquid crystal material on the first substrate; a presser which, in cooperation with said support, presses the second substrate against the first substrate on which the liquid crystal material has been dispensed; and a mechanism which relatively moves said presser against said support. EP2998786A1 discloses a light shutter comprising : a cell (301) comprising a first substrate (90) and a second (90) substrate spaced apart from said first substrate by a distance, and a layer (1201) between said substrates containing a chiral nematic liquid crystal (10) whose pitch is less than the distance between said substrates, a surface of said layer adjacent said second substrate comprising a monolayer of protrusions (114) projecting into said layer, the centre-to-centre distance (900) of said protrusions being greater than said pitch; wherein in the absence of an electrical field said chiral nematic liquid crystal aligns in polydomain (20, 21) in said layer and said protrusions stabilize said polydomains over time, and said cell prevents visual access through said shutter; and wherein in the presence of an electrical field said liquid crystal aligns with a common identifiable alignment (11) in one axis and said cell provides visual access through said shutter. BRIEF DESCRIPTION OF THE DRAWINGS Illustrative embodiments are described with reference to the following figures: FIG. 1A and FIG. 1B illustrate an example of a dimmable glass and its applications.FIG. 2A - FIG. 2C illustrate an example of a liquid crystal cell and its operations.FIG. 3A - FIG. 3C illustrate a dimmable laminated glass including a liquid crystal cell.FIG. 4A and FIG. 4B illustrate another example of a liquid crystal cell according to embodiments of the present disclosure.FIG. 5A - FIG. 5D illustrate examples of a dimmable laminated glass according to embodiments of the present disclosure.FIG. 6 illustrates another example of a dimmable laminated glass according to embodiments of the present disclosure.FIG. 7 illustrates an example of a method of fabricating a liquid crystal cell according to embodiments of the present disclosure.FIG. 8 illustrates an example of a roll-to-roll operation to fabricate a liquid crystal cell according to embodiments of the present disclosure. The figures depict embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated may be employed without departing from the principles, or benefits touted, of this disclosure. In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the si