KR-20260066198-A - Piezoelectric electrophoretic film and display, and method of manufacturing the same

KR20260066198AKR 20260066198 AKR20260066198 AKR 20260066198AKR-20260066198-A

Abstract

A low-voltage piezoelectric electrophoretic display comprising a low-profile piezoelectric electrophoretic display. In some embodiments, the piezoelectric material of the piezoelectric electrophoretic film may be optionally patterned with an insulating material during manufacturing. In some embodiments, the piezoelectric material of the piezoelectric electrophoretic film may be optionally patterned with a cut section or partially coated with a conductive material on a surface opposite to the electrode. Such films have a high contrast ratio and are useful as security markers, authentication films, or sensors. The films are generally flexible. Some films have a thickness of less than 100 μm. Some films have a thickness of less than 50 μm. Displays formed from such films do not require an external power source.

Inventors

마투스 유리 보리소비치
구 하이얀

Assignees

이 잉크 코포레이션

Dates

Publication Date: 20260512
Application Date: 20241226
Priority Date: 20231231

Claims (20)

A method for manufacturing a piezo-electrophoretic display comprising a first electrode and a second electrode, Step of forming a layer of microcells - said microcells have a bottom, a wall, and a top opening - ; A step of filling the microcells with an electrophoretic medium through the upper opening; A step of creating a sealing layer by sealing the upper opening of the filled microcells with a water-soluble polymer; A step of bonding the second electrode with the sealing layer; A step of processing a film of a piezoelectric material to form a piezoelectric layer comprising one or more voids in the piezoelectric material; A step of bonding the piezoelectric layer to a layer of microcells on a surface opposite to the sealing layer; and A step of forming the first electrode by depositing an electrically conductive material on the piezoelectric layer - the electrically conductive material fills one or more voids in the piezoelectric material and coats the surface of the piezoelectric layer - A method for manufacturing a piezoelectric electrophoretic display comprising
In claim 1, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrically conductive material of the first electrode comprises poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS).
In claim 1, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrically conductive material of the first electrode filling one or more voids in the piezoelectric material is in contact with the layer of microcells.
In claim 1, A method for manufacturing a piezoelectric electrophoretic display, wherein the second electrode comprises an electrically conductive material coupled to a substrate.
In claim 1, A method for manufacturing a piezoelectric electrophoretic display, further comprising the step of bonding the piezoelectric electrophoretic display to a target object including one of paper, banknotes, and currency.
In claim 1, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrophoretic medium comprises a nonpolar fluid and charged pigment particles, wherein the charged pigment particles move toward or away from the piezoelectric layer when the piezoelectric layer is subjected to mechanical stress, and the nonpolar fluid and charged pigment particles are sealed within the microcell by the sealing layer.
In claim 1, A method for manufacturing a piezoelectric electrophoretic display in which the above-mentioned piezoelectric layer is polarized using an electric field.
In a method for manufacturing a piezoelectric electrophoretic display, A step of processing a film of a piezoelectric material on a release film to form a piezoelectric layer containing one or more voids in the piezoelectric material; A step of forming a first electrode by depositing an electrically conductive material on the piezoelectric layer - the electrically conductive material fills one or more voids in the piezoelectric material and coats the surface of the piezoelectric layer - ; Step of forming a layer of microcells - said microcells have a bottom, a wall, and a top opening - ; A step of filling the microcells with an electrophoretic medium through the upper opening; A step of creating a sealing layer by sealing the upper opening of the filled microcells with a water-soluble polymer; A step of bonding the second electrode to the sealing layer; A step of removing the release film from the piezoelectric layer; and A step of bonding the piezoelectric layer to the layer of microcells on a surface opposite to the sealing layer. A method for manufacturing a piezoelectric electrophoretic display comprising
In claim 8, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrically conductive material of the first electrode comprises poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS).
In claim 8, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrically conductive material of the first electrode filling one or more voids in the piezoelectric material is in contact with the layer of microcells.
In claim 8, A method for manufacturing a piezoelectric electrophoretic display, wherein the second electrode comprises an electrically conductive material bonded to a substrate.
In claim 8, A method for manufacturing a piezoelectric electrophoretic display, further comprising the step of bonding the piezoelectric electrophoretic display to a target object including one of paper, banknotes, and currency.
In claim 8, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrophoretic medium comprises a nonpolar fluid and charged pigment particles, wherein the charged pigment particles move toward or away from the piezoelectric layer when the piezoelectric layer is subjected to mechanical stress, and the nonpolar fluid and charged pigment particles are sealed within the microcell by the sealing layer.
In claim 8, A method for manufacturing a piezoelectric electrophoretic display in which the above-mentioned piezoelectric layer is polarized using an electric field.
In a method for manufacturing a piezoelectric electrophoretic display, A step of bonding a first electrode with a piezoelectric layer comprising polyvinylidene fluoride (PVDF); A step of forming one or more conductive segments on the surface of the piezoelectric layer opposite to the first electrode; Step of forming a layer of microcells - said microcells have a bottom, a wall, and a top opening - ; A step of filling the microcells with an electrophoretic medium through the upper opening; A step of creating a sealing layer by sealing the upper opening of the filled microcells with a water-soluble polymer; A step of bonding the second electrode to the sealing layer; and A step of bonding the piezoelectric layer and the one or more conductive segments to a layer of microcells on a surface opposite to the sealing layer. A method for manufacturing a piezoelectric electrophoretic display comprising
In claim 15, A method for manufacturing a piezoelectric electrophoretic display, wherein the electrically conductive material of the first electrode comprises poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT-PSS).
In claim 15, A method for manufacturing a piezoelectric electrophoretic display, wherein the second electrode comprises an electrically conductive material bonded to a substrate.
In claim 15, A method for manufacturing a piezoelectric electrophoretic display, further comprising the step of bonding the piezoelectric electrophoretic display to a target object including one of paper, banknotes, and currency.
In claim 15, A method for manufacturing a piezoelectric electrophoretic display in which the above-mentioned piezoelectric layer is polarized using an electric field.
In claim 15, A method for manufacturing a piezoelectric electrophoretic display, wherein one or more conductive segments have a thickness of approximately 50 to 100 nm.

Description

Piezoelectric electrophoretic film and display, and method of manufacturing the same Cross-reference regarding related applications This application claims priority to U.S. Provisional Application No. 63/616,721 filed December 31, 2023, the entire contents of which are incorporated herein by reference. Additionally, the entire contents of any patent, published application, or other published work referenced herein are incorporated by reference. Field of the present invention The present invention relates to an electrophoretic display, in particular to a thin piezo-electrophoretic display having an improved contrast ratio, and a method for manufacturing the same. An electrophoretic display (EPD) is a non-luminous device based on the electrophoresis of charged pigment particles dispersed in a solvent or solvent mixture. The display typically comprises two electrodes positioned opposite each other that provide an electric field to drive the movement of the charged pigment particles. One of the electrodes is usually transparent. When a voltage difference is applied between the two electrodes, the pigment particle(s) move to one side or the other, causing the color of the pigment particles or the color of the solvent (if colored) to be visible from the viewing side. The electrophoretic fluid typically comprises a non-polar solvent and a set of one or more charged particles. The particles may have different optical properties (color), different charges (positive or negative), different charge magnitudes (zeta potential), and/or different absorption properties (wide light absorption, wide light reflection, or selective absorption or selective reflection). In the case where there are multiple sets of particles with opposite charge polarities, the application of an electric field can cause one set of particles to appear on the viewing surface while moving the other particles away from the viewing surface. Many electrophoretic displays are bistable, meaning that their optical state persists even after the activating electric field is removed. This bistable is primarily due to an induced dipole charge layer formed around the charged pigment resulting from complex interactions between the pigment dispersed in the solvent, the charge controller, and the free polymer. Bistable displays can persist for years in their last addressed optical state before being switched back by the application of a new driving electric field. Driving an electrophoretic display requires a power source to provide an electric field between the electrodes. The power source is typically a battery that provides power to the electrodes through a driving circuit. One or more electrodes may be integrated into an active matrix backplane. The power source may also be, for example, a photovoltaic cell, a fuel cell, or a power source operating from a wall current. The power source may also be a piezoelectric element that generates charge through physical motion or thermal expansion, as described in U.S. Patent No. 5,930,026, the whole of which is incorporated by reference. In all these examples, some type of driving circuit is required to provide an electrical path between the power source and the electrodes, and typically, the circuit includes control elements such as switches, transistors, etc. In most cases, the circuit is fairly routine, but this typically adds volume and structural constraints (i.e., inflexibility or inability to twist) to the final display. Furthermore, for many applications, it is desirable to reduce the overall thickness of the display. However, the thickness of the piezoelectric material layer generally has a direct correlation with the amplitude of the voltage that the piezoelectric material can generate in response to mechanical stress. That is, reducing the thickness of the piezoelectric material reduces the magnitude of the voltage generated by the piezoelectric material under stress (and vice versa). Accordingly, in order to generate a voltage potential large enough to cause sufficient movement of charged pigment particles necessary to achieve an acceptable contrast ratio, conventional piezoelectric electrophoretic displays typically incorporated a layer of piezoelectric material that is too thick for use in applications requiring durability, as such displays must be practically invisible when integrated into thin, low-profile end products such as paper or banknotes. In addition, conventional piezoelectric electrophoretic displays are typically constructed using a continuous layer of piezoelectric material, which generates charge outside the desired area when subjected to mechanical stress. For example, if mechanical stress is applied to an area of the piezoelectric layer larger than the part containing the security seal or image, the piezoelectric material in the part outside the security seal or image will generate charge that moves the charged pigments near these parts. Due to the effects described above, bending a porti