TWI869324B - Back panel for electrophoretic display and electrophoretic display thereof - Google Patents

Abstract

The present invention is related to a back panel for an electrophoretic display, including: a water-barrier substrate layer; a plurality of conductive traces arranged on the water-barrier substrate layer; a passivation layer arranged on the water-barrier substrate layer and the conductive traces, and the passivation layer including a plurality of reserved openings; and a plurality of electrode blocks provided on the passivation layer, and extending into the reserved openings so as to electrically connect to the corresponding conductive traces, wherein each electrode block corresponds to more than three reserved openings, and an equivalent diameter of the reserved openings is between 0.2-1.0mm.

Description

Back plate for electrophoretic display and electrophoretic display

The present invention relates to a backplane for an electrophoretic display and the electrophoretic display, in particular to a backplane with a water-blocking film as a substrate for a printing process.

The main principle of electrophoretic display is to use an external electric field to drive the charged dye particles suspended in microcapsules or microcup solutions to display images by using the change in the location of the dye particles. It has been widely used in the market of electronic readers (such as e-books, e-newspapers or e-notebooks) or other electronic components (such as electronic labels, electronic billboards).

Segmented Display is one of the products of electrophoretic display. Its principle is that each segment (segment or block) corresponds to a driving line, and multiple blocks can be assembled to display numbers or simple graphics. Segmented Display can produce a variety of 2D shapes, such as circles, triangles and irregular shapes, etc., strengthening the needs of industrial design, and can be applied to a variety of industries such as clothing, car bodies, household goods, industrial products and architectural exterior decoration.

However, in the known block display manufacturing process, the traditional printed circuit board manufacturing process is adopted, and the printed circuit board is punched so that the conductive layers on the upper and lower sides of the printed circuit board can be connected through the perforations, the conductive layer on the upper side of the substrate is specially imaged, and the conductive layer on the lower side of the substrate is used as a driving circuit and connected to the signal input terminal. Because the ink material needs to be in a specific water content state to achieve the best display effect, it is necessary to add a water-blocking film to the outermost layer of the module to prevent moisture from the external environment from entering the display, causing the water content of the ink material to change, thereby affecting the display effect. Therefore, after the conventional backplane is manufactured, an additional adhesive is required to attach the water-blocking film to the outermost layer of the backplane. This structure increases the thickness of the entire display, which is not conducive to the development of thinner products. The adhesive used is also prone to produce byproducts such as volatile gases during the manufacturing process, such as volatile organic compounds (VOCs). VOCs react chemically with nitrogen oxides mainly from automobiles and industrial activities to form ozone. The accumulation of ozone, particulates in the air and other pollutants will form smog, causing air quality deterioration, and therefore does not meet environmental protection requirements.

In addition, printed circuit boards are made of multiple layers of materials that are stamped. During the perforation process (such as CNC drilling), dust is generated, which may pollute the environment. Dust is also easily retained on the hole wall. During the reflow process, it expands under the heat effect of temperature rise and hot air convection, causing dust to fall off and cause secondary pollution of the printed circuit board. The above problems may require additional equipment on the production line, such as blowing equipment, high-pressure dust collection equipment, etc., to be solved, which is not conducive to improving production efficiency and is harmful to the environment.

Therefore, it is necessary to provide a display back plate that can omit the perforation step, the bonding process, and reduce the thickness of the overall display stack to overcome the above problems.

In order to effectively solve the above problems, the present invention provides a backplane for an electrophoretic display, comprising: a water-blocking substrate layer; a plurality of conductive traces disposed on the water-blocking substrate layer; an insulating layer disposed on the water-blocking substrate layer and the conductive traces, and the insulating layer has a plurality of reserved openings; and a plurality of electrode blocks disposed on the insulating layer and extending into the reserved openings to be electrically connected to the corresponding conductive traces, wherein each of the electrode blocks corresponds to more than three reserved openings, and wherein the equivalent diameter of each of the reserved openings is between 0.2-1.0 mm.

The present invention proposes a backplane for an electrophoretic display, which helps to meet the ESG requirements of enterprises. ESG refers to environmental protection (Environmental), social responsibility (Social) and corporate governance (Governance), which can be regarded as a kind of data and indicators for evaluating enterprises. Therefore, the process and its products proposed by the present invention are more environmentally friendly, such as using low-pollution materials and processes, in order to meet the requirements of ESG.

Preferably, the contact impedance between each electrode block and the corresponding conductive trace is less than 1×10 ^-4 Ω/cm. Or the overall impedance of the conductive circuit formed by each electrode block and the corresponding conductive trace is less than 700Ω.

Preferably, the contact impedance between each electrode block and the corresponding conductive trace is less than 1×10 ^-4 Ω/cm, and the overall impedance of the conductive line formed by the two is less than 700Ω.

Preferably, the glass transition temperature of the water-blocking substrate layer is greater than 80°C.

Preferably, the conductive trace is formed by solidifying silver slurry, and the thickness of the conductive trace is less than 6 μm.

Preferably, the thickness of the insulating layer is between 3 and 10 μm, or the thickness of the insulating layer is less than 20 μm.

Preferably, the electrode block is formed by a slurry containing conductive carbon black. Alternatively, the electrode block is formed by printing a conductive slurry containing conductive carbon black.

Preferably, the depth-to-width ratio of the reserved opening is between 10um/mm and 50um/mm.

Preferably, the overall impedance of each electrode block and the corresponding conductive trace is less than 700Ω. Alternatively, the overall impedance of each electrode block and the corresponding conductive trace is less than 200Ω.

Preferably, the water-oxygen transmission rate of the water-blocking substrate layer is between 1 g/m ² /day and 0.01 g/m ² /day.

Preferably, the water-blocking substrate layer includes a PET layer and a material layer, wherein the material layer includes a water-blocking coating layer or an aluminum layer.

Preferably, the water-blocking coating comprises two layers of silicon nitride or silicon oxide with different thicknesses, or the water-blocking coating comprises two layers of materials with different water-blocking rates.

In addition, in order to effectively solve the above-mentioned problems, the present invention further proposes a method for manufacturing a backplane for an electrophoretic display, comprising: forming a water-blocking substrate layer; printing a plurality of conductive traces on the water-blocking substrate layer; printing an insulating layer on the water-blocking substrate layer and the conductive traces, and the insulating layer has a plurality of reserved openings; and printing a plurality of electrode blocks on the insulating layer to extend into the reserved openings to be electrically connected to the corresponding conductive traces, wherein each of the electrode blocks corresponds to more than three reserved openings, and wherein the equivalent diameter of each of the reserved openings is between 0.2-1.0 mm.

In order to effectively solve the above problems, the present invention further proposes an electrophoretic display, comprising: a water-blocking substrate layer; a plurality of conductive traces disposed on the water-blocking substrate layer; an insulating layer disposed on the water-blocking substrate layer and the conductive traces, and the insulating layer has a plurality of reserved openings; and a plurality of electrode blocks disposed on the insulating layer and extending from the reserved openings. wherein each of the electrode blocks corresponds to more than three reserved openings, and wherein the equivalent diameter of each of the reserved openings is between 0.2-1.0 mm; an electrode layer; and an electronic ink layer; wherein the electronic ink layer is driven by the electrode blocks and the electrode layer to display at least one color block.

In order to enable persons familiar with the art to understand the purpose, features and effects of the present invention, the present invention is described in detail as follows through the following specific embodiments and in conjunction with the attached drawings.

The inventive concept will now be more fully explained below with reference to the accompanying drawings in which exemplary embodiments of the inventive concept are shown. The advantages and features of the inventive concept and the methods for achieving the same will become apparent by describing the exemplary embodiments in more detail below with reference to the accompanying drawings. However, it should be noted that the inventive concept is not limited to the following exemplary embodiments, but can be implemented in various forms. Therefore, the exemplary embodiments are provided only to disclose the inventive concept and to enable those skilled in the art to understand the category of the inventive concept. In the drawings, exemplary embodiments according to the inventive concept are not limited to the specific embodiments provided herein, and the drawings are exaggerated for clarity.

The terms used herein are used only to describe specific embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, the singular forms of the terms "a", "an" and "the" used herein are intended to include the plural forms as well. The term "and/or" used herein includes any and all combinations of one or more of the relevant listed items. It should be understood that when an element is said to be "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element or there may be intermediate elements.

Similarly, it should be understood that when an element (such as a layer, region, or substrate) is said to be "on" another element, the element may be directly on the other element, or there may be intervening elements. In contrast, the term "directly" means that there are no intervening elements. It should be further understood that when the terms "include" and "comprising" are used herein, they indicate the presence of the stated features, integers, steps, operations, elements, and/or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Furthermore, exemplary embodiments in the detailed description will be illustrated by cross-sectional views that are idealized exemplary views of the inventive concept. Accordingly, the shapes of the exemplary views may be modified according to manufacturing techniques and/or tolerable errors. Therefore, exemplary embodiments of the inventive concept are not limited to the specific shapes shown in the exemplary views, but may include other shapes that may be produced according to the manufacturing process. The areas illustrated in the drawings are of general nature and are used to illustrate specific shapes of the elements. Therefore, this should not be considered as limiting the scope of the inventive concept.

It should also be understood that although the terms "first", "second", "third", etc. may be used herein to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish between various elements. Therefore, the first element in some embodiments may be referred to as the second element in other embodiments without departing from the teachings of the present invention. The exemplary embodiments of the aspects of the inventive concept explained and illustrated herein include their complementary counterparts. Throughout this specification, the same element number or the same indicator represents the same element.

Furthermore, exemplary embodiments are described herein with reference to cross-sectional views and/or plan views, wherein the cross-sectional views and/or plan views are idealized exemplary illustrations. Therefore, deviations from the illustrated shapes due to, for example, manufacturing techniques and/or tolerances are expected. Therefore, the exemplary embodiments should not be considered limited to the shapes of the regions shown herein, but are intended to include shape deviations due to, for example, manufacturing. Therefore, the regions shown in the figures are schematic, and their shapes are not intended to illustrate the actual shapes of the regions of the device, nor are they intended to limit the scope of the exemplary embodiments.

The term "bistable" or the like herein refers to a display having first and second display states that are different in at least one optical property, and can change between the first and second display states after receiving a driving source, and is stable in the first and second display states. In addition, some displays are also stable in the intermediate state between the first and second display states, and such displays may be referred to as "multi-stable", but for ease of understanding, the term "bistable" or the like herein may cover multi-stable displays.

Some embodiments of the present invention are directed to electro-optical displays, particularly dual-stable electro-optical displays, such as an electrophoretic display based on particle reflection of light, wherein one or more types of colored (black, white or colored)/charged particles are present in a fluid (hereinafter referred to as an electrophoretic medium) and move in the fluid under the influence of an electric field or/and a magnetic field to change the display appearance (or display screen) of the display. The color electrophoretic display of some embodiments of the present invention has a material (i.e., colored/charged particles) that can produce a first and a second display state, and by applying an electric field or/and a magnetic field to the material, the appearance of the material is changed from the first display state to the second display state, and at least one optical property (such as hue, lightness and chroma) of the first and second display states can be the same or different.

It is understood that the present invention is related to a backplane of a display, which can be used to drive an electrophoretic display and achieve a good water-blocking effect. This backplane can be used with any applicable display. Generally, the display may include but is not limited to a water-blocking film, an optical glue, an upper electrode corresponding to the electrode block of the present case, an electronic ink layer, an LCD, an OLED, etc.

Please refer to FIG. 1, which is a cross-sectional view of a display backplane 1 according to a preferred embodiment of the present invention. The display backplane 1 includes: a water-blocking substrate layer 10; a conductive trace 20 disposed on the water-blocking substrate layer 10; an insulating layer 30 disposed on the water-blocking substrate layer 10 and the conductive trace 20, and a plurality of reserved openings 40 are formed on the insulating layer 30; and a plurality of electrode blocks 50 are disposed on the insulating layer 30, filled in the reserved openings 40 and electrically connected to the corresponding conductive traces 20 through the reserved openings 40.

Please refer to Fig. 2, which is a cross-sectional view of a display according to an embodiment of the present invention. In Fig. 2, the display back plate 1 of the embodiment of the present invention shown in Fig. 1 and the electronic ink layer 60, the first driving electrode 70 and the cover plate 80 constitute the display of the embodiment of the present invention. The electronic ink layer 60 is substantially disposed between the display back plate 1 and the first driving electrode 70, and is driven by the electric field/magnetic field between the two to present a color or pattern. FIG. 3 is a front perspective view of a display according to an embodiment of the present invention. The display according to an embodiment of the present invention can display a plurality of blocks 100A, 100B, 100C, 100D, 100E, and 100F. For block 100A, its electronic ink layer 60 is driven by a first driving electrode 70 (referred to as an upper electrode layer) and a second driving electrode (i.e., an electrode block 50A corresponding to block 100A, referred to as a lower electrode layer). ) between the voltage control (e.g. +15V, -15V, 0V, etc.), the colored particles (such as black, white or other colors)/charged particles in the electronic ink layer 60 move in the fluid, so that the block 100A presents a display appearance, color (or display screen), that is, the multiple blocks 100A, 100B, 100C, 100D, 100E, 100F of the display of the embodiment of the present invention can present color blocks or patterns. For example, the block 100B displays white (screen background), the block 100A displays green, the block 100C displays black, the blocks 100D and 100F display red, and the block 100E displays yellow. Please refer to FIG. 5 again. FIG. 5 is a front perspective view of another display of an embodiment of the present invention, which can be applied as an indicator light to display the battery capacity of electronic products. For example, block 200E is 0-20% of the total power, displayed in red; block 200A is 80-100% of the total power, displayed in green, and blocks 200B, 200C, and 200D are displayed in blue, yellow, and orange, respectively.

The following first describes in detail the various components and manufacturing processes of the display back plate 1 of the embodiment of the present invention.

First, a water-blocking substrate layer 10 is provided. The water-blocking substrate layer 10 is composed of a water-blocking substrate, which can be divided into inorganic (e.g., SiO ₂ , aluminum film) materials, organic materials, or a combination of the two. Since the present invention requires printing structures such as conductive traces 20, insulating layers 30, and electrode blocks 50 on the water-blocking substrate layer 10, the material selection of the water-blocking substrate layer 10 should consider heat resistance, support (e.g., tensile strength) and other surface characteristics (e.g., surface roughness may affect the printing accuracy, and materials with surface characteristics Ra≒0.5nm can be selected) during the manufacturing process. In the embodiment of the present invention, the water-blocking substrate layer 10 can withstand the printing process temperature of the conductive traces 20, the insulating layer 30, and the electrode block 50. That is, the glass transition temperature (Tg) of the water-blocking substrate layer 10 can be greater than 80°C, greater than 100°C, greater than 160°C, or greater than 200°C to ensure sufficient heat resistance.

Please refer to Table 1. In the embodiment of the present invention, the properties of the water-blocking substrate 10 are selected. In Table 1, the standard is whether the water-blocking property reaches a water oxygen permeability of <0.5g/ ^m2 /day, the standard is whether the supporting property reaches a tensile strength of >100MPa, and the standard is whether the heat resistance reaches a glass transition temperature (Tg) of >80°C. Among them, Δ indicates that the supplier did not provide specific data, X indicates that the requirements of the present invention are not met, and O indicates that the requirements of the present invention are met.

Table 1 First comparison ratio Second comparison ratio First Embodiment Second Embodiment Water-blocking substrate layer material PI PET PET+water-blocking coating PET+ Aluminum Water barrier Δ X O O Support O - O O Heat resistance O - O O

In the first comparative example in Table 1, the polyimide (PI) film provided by the supplier does not have specific water permeability data, but after testing, the water barrier of the PI film cannot pass the requirements. The reason is presumed to be that it is a condensed PI film. Since the synthesis reaction of the condensed PI is carried out in a high-boiling point inert solvent, and the high-boiling point inert solvent is difficult to completely evaporate during the prepreg preparation process, and volatiles are also released during the heating of polyamide cyclization (imidization), thereby generating pores on the PI film. These holes left in the process are possible paths for water vapor to enter the product, making the electronic ink layer 60 ineffective.

In Table 1, the combination of PET and a water-blocking coating is a composite substrate, and the water-blocking coating can be one or more layers of organic or inorganic materials. In one embodiment, the water-blocking coating can be a layer of silicon oxide (SiOx) or silicon nitride (SiNx), Al ₂ O ₃ , MgAl ₂ O ₄ , Parylene or Polypropylene, and the water-oxygen permeation rate of the water-blocking coating is approximately between 0.5 g/m ² /day and 0.01 g/m ² /day, and its thickness is approximately between 10 and 300 nm, preferably between 50 and 250 nm. In one embodiment, the water-blocking coating may be two layers of silicon nitride or silicon oxide, the water-oxygen transmission rate of the first water-blocking coating is approximately between 0.5 g/m ² /day and 0.01 g/ ^{m 2} /day, and its thickness is approximately between 10 and 300 nm, preferably 50 to 250 nm; the second water-blocking coating is located between the first water-blocking coating and the PET substrate, the water-oxygen transmission rate of the second water-blocking coating is approximately between 1 g/m ² /day and 0.1 g/ ^{m 2} /day, and its thickness is approximately between 100 and 500 nm, preferably, the thickness of the second water-blocking coating is greater than the thickness of the first water-blocking coating.

In the first embodiment, a layer of silicon nitride with a thickness of about 60nm is coated on PET, and its water and oxygen permeation rate is about 0.05g/ ^m2 /day, while the water and oxygen permeation rate of PET is about 20g/ ^m2 /day. After testing, the substrate of this structure can meet the requirements of the present invention in terms of water barrier, support and heat resistance.

In the second embodiment in Table 1, the combination of PET and aluminum (Al) layer is a composite substrate, and its overall water oxygen transmission rate is roughly between 1g/m2/ ^day and 0.01g/ ^m2 /day. In one embodiment, a composite substrate of PET and aluminum (Al) with an overall water oxygen transmission rate of about 0.3g/ ^m2 /day and 0.5g/ ^m2 /day is selected. After testing, the substrate of this structure can meet the requirements of the present invention in terms of water barrier, support and heat resistance.

In contrast, the second comparative example in Table 1 uses only PET with a water-oxygen permeability of about 20 g/m ² /day, and its high water permeability will cause the failure of the electronic ink layer 60. It is worth noting that since the water permeability of the PET substrate does not meet the requirements, the support and heat resistance are not verified, and only "-" is used as a mark in Table 1. In the embodiment of the present invention, the water-oxygen permeability of the water-blocking substrate layer 10 can be less than 0.5 g/m ² /day, or less than 0.1 g/m ² /day or less than 0.01 g/m ² /day.

It is understandable that after using the water-blocking substrate as the water-blocking substrate layer 10, the present invention reduces the thickness of the substrate in the conventional structure, that is, in the conventional technology, the backplane includes a water-blocking film, a substrate, and a glue material that adheres the water-blocking film to the substrate. However, in the present invention, since the water-blocking substrate layer 10 can provide the dual functions of supporting the substrate and water-blocking, the overall thickness can be reduced while saving one layer of material.

Then, a conductive trace 20 is arranged on the water-blocking substrate layer 10. The conductive trace 20 is used to transmit electrical signals to the electrode block 50 to control/drive the electronic ink layer 60. Therefore, it can be understood that the display backplane 1 includes a plurality of conductive traces 20. For example, as shown in FIG. 3, each block 100A, 100B, 100C, 100D, 100E, 100F has its corresponding conductive trace 20A, 20B, 20C, 20D, 20E, 20F and reserved openings 40A, 40B, 40C, 40D, 40E, 40F. The conductive trace 20 should be as thin as possible to avoid affecting the display of the pattern. In addition, since the display backplane 1 does not require light transmission, the conductive trace 20 can use a low-impedance metal material such as carbon paste, silver paste or copper metal to increase the response speed and display effect of the display. According to the preferred embodiment of the present invention, the conductive trace 20 is printed with silver paste on the water-blocking substrate layer 10, and then solidified to form a line resistance preferably less than 100Ω (surface resistance ≤ 0.1 Ω/sq). The general curing temperature of silver paste is about 200°C, so the aforementioned water-blocking substrate layer 10 needs to be selected with a suitable material (i.e., it must have sufficient heat resistance) in accordance with the curing temperature of the silver paste. The blocks 200A, 200B, 200C, 200D, and 200E shown in FIG5 all have their corresponding conductive traces 20A, 20B, 20C, 20D, and 20E and reserved openings 40A, 40B, 40C, 40D, and 40E. The contents drawn in FIG5 may all refer to the specific description of FIG3 below.

In the third embodiment, a composite material of PET and aluminum (Al) with an overall water oxygen transmission rate of about 0.5g/ ^m2 /day and a thickness of about 100μm is selected as the substrate, and then a silver paste (supplier INKTEC; model: TEC-PA-051) is used to print the conductive trace 20. The specific process is: the conductive silver paste is uniformly printed on the PET/Al composite substrate by screen printing to form the conductive trace 20, and then baked in a blast oven at 80°C for 50-60 minutes, taken out, and cooled. In this embodiment, the thickness of the conductive trace 20 is less than 6μm. In another embodiment, the thickness of the conductive trace 20 is about 3-4μm, and the line resistance is about 40-50Ω. Subsequent tests have found that when the thickness of the conductive trace 20 is too thick (for example, greater than 6 μm), the viewer will observe the trace of the conductive trace 20 when the electronic ink layer 60 displays color, which is a visually undesirable effect. From the perspective of the printing process, if the thickness of the silver paste material is reduced during printing, the silver paste will not be accurately formed due to fluid diffusion. The silver paste selected in the present embodiment has a higher viscosity, for example, greater than 170,000 cp, greater than 190,000 cp, or greater than 250,000 cp, so the fluidity of the silver paste material can be controlled to print a thin and high-precision conductive trace 20.

In the fourth embodiment, a composite material of PET and aluminum (Al) with an overall water oxygen transmission rate of about 0.5 g/m ² /day and a thickness of about 100 μm is selected as the substrate, and silver paste (supplier DuPont; model: PV416) is printed by screen printing, and baked in a 130°C forced air oven for 120 minutes, then taken out and cooled to form a conductive trace 20.

Then, an insulating layer 30 is disposed on the water-blocking substrate layer 10 and the conductive traces 20, and a reserved opening 40 is formed on the insulating layer 30, and the reserved opening 40 exposes the corresponding conductive traces 20. The insulating layer 30 can be formed of materials such as resin. In addition, the thickness of the insulating layer 30 cannot be too small, otherwise the insulation is insufficient to isolate the conductive trace 20 from the subsequent electrode block 50; but the thickness cannot be too large, otherwise a reserved opening 40 with a large aspect ratio will appear on the insulating layer 30, which may cause defects in the electrode block 50 and affect the display of the pattern. According to the preferred embodiment of the present invention, the thickness of the insulating layer 30 should be between 3-10μm, or between 4-6μm, or between 8-10μm.

In the fifth embodiment, a composite material of PET and aluminum (Al) with an overall water oxygen transmission rate of about 0.5 g/m ² /day and a thickness of about 100 μm is selected as the substrate, and a silver paste (supplier INKTEC; model: TEC-PA-051) is used to print the conductive traces 20. The specific process is as follows: conductive silver paste is uniformly printed on the PET/Al composite substrate by screen printing, and then baked in a blast oven at 80°C for 50-60 minutes, taken out, and cooled to form a conductive trace 20 with a thickness of about 3-4μm; then the resin material (supplier: Guangxin Photosensitive New Material; model: KSM-S6189) is printed with a 450-mesh screen, and cured at 80°C to form an insulating layer 30 with a surface impedance of ≥1.0×10¹²Ω and a thickness of about 10μm. In addition, during the printing process, a printing hole position is directly reserved to form the aforementioned reserved opening 40. The reserved opening 40 of this embodiment is a circular hole with a diameter of 0.6mm, and the position of the circular hole will correspond to the conductive trace 20 to expose it.

In the sixth embodiment, except that the thickness of the insulating layer is about 4 μm and the reserved opening 40 is a circular hole with a diameter of 0.2 mm, other conditions are the same as those of the fifth embodiment.

In the seventh embodiment, except that the thickness of the insulating layer is about 8 μm and the reserved opening 40 is a circular hole with a diameter of 0.2 mm, other conditions are the same as those of the fifth embodiment.

It is understood that in the subsequent manufacturing process, the conductive traces 20 are electrically connected to the plurality of electrode blocks 50 through the reserved openings 40. Therefore, the insulating layer 30 should include a plurality of reserved openings 40 so that the plurality of conductive traces 20 are electrically connected to the corresponding electrode blocks 50. Here, the reserved opening 40 should have a specific size, that is, a suitable aspect ratio. For example, if the aspect ratio of the reserved opening 40 is too large, the upper surface of the printed electrode block 50 is easy to sink, which will affect the display function and color of the display, or if the aspect ratio of the reserved opening 40 is too small, the printed paste of the electrode block 50 may not be easy to fill into the reserved opening 40, which will cause electrical disconnection. Therefore, in the present invention, in order to ensure that the reserved opening 40 has a suitable aspect ratio, the equivalent diameter of each reserved opening 40 should be between 0.2-1.0 mm. It is understood that the shape of the reserved opening 40 of the present invention is not limited to a circle, for example, it can be an ellipse, a square, a triangle, a polygon, etc., as long as the area of the reserved opening 40 can correspond to the area of a circle with a diameter between 0.2-1.0 mm. The "equivalent" diameter referred to herein refers to the width of the opening under different shapes, for example, the diameter corresponds to a circular opening, the side length corresponds to a polygonal opening, etc.

In one embodiment, the depth-to-width ratio of the reserved opening 40 is between 10 μm/mm and 50 μm/mm, preferably between 15 μm/mm and 30 μm/mm, and preferably between 20 μm/mm and 25 μm/mm. In one embodiment, the thickness of the insulating layer 30 is less than about 20 μm (i.e., the depth of the reserved opening 40 is also equivalent to the thickness of the printed paste of the electrode block 50). If it exceeds 20 μm, it will be observed that the bottom layer of the insulating layer 30 cannot be completely cured, and the edge of the reserved opening 40 is prone to side concavity. In addition, the insufficient dryness of the insulating layer 30 will also affect the printing accuracy of the electrode block 50.

In addition, it is understood that the present invention "reserve" a plurality of reserved openings 40 at positions corresponding to the conductive traces 20 when printing the insulating layer 30 (that is, the positions of the reserved openings 40 are designed in advance during printing, and the printed material is not applied to the reserved positions), so that the conductive traces 20 can be electrically connected to the plurality of electrode blocks 50 through the reserved openings 40, and therefore, no additional drilling process is required. Since the drilling process is omitted, not only the cost is saved, but also the defects caused by the drilling alignment error can be avoided and the environmental pollution caused by the dust generated by the drilling can be reduced.

Then, an electrode block 50 is disposed on the insulating layer 30, and is filled into the reserved opening 40 and extends through the reserved opening 40 to be electrically connected to the corresponding conductive trace 20. The electrode block 50 can be formed of a material such as a slurry containing conductive carbon black. The characteristics (such as shape, size, and position) of the electrode block 50 are substantially the same as the electronic ink layer 60 driven by it, so as to display the individual colors of the aforementioned blocks 100A to 100F and blocks 200A to 200E. It is worth noting that the term reserved opening 40 mainly refers to the position deliberately left empty when printing the insulating layer 30. In the step of printing the electrode block 50, the material of the electrode block 50 will be filled into the reserved opening 40, thereby forming a conductive filled hole. In other words, the reserved opening 40 no longer has a through-hole shape after a specific step, but is a closed hole filled with material. To avoid confusion, the present invention no longer gives a new number to the filled closed hole, and the number 40 is still used.

In the third comparative example, a composite material of PET and aluminum (Al) with an overall water oxygen transmission rate of about 0.5g/ ^m2 /day and a thickness of about 100μm was selected as the substrate. Then, a conductive silver paste (supplier INKTEC; model: TEC-PA-051) was uniformly printed on the PET/Al composite substrate by screen printing, and then baked in a forced air oven at 80°C for 50-60 minutes, taken out, and cooled to form a conductive trace with a thickness of about 3-4μm. ; Then, a high-impedance resin material (supplier: Guangxin Photosensitive New Materials; model: KSM-S6189) is screen-printed (450 mesh) and cured at 80°C to form an insulating layer 30 with a surface impedance of ≥1.0×10¹²Ω and a thickness of about 4μm, on which there is a reserved opening 40 in the shape of a circular hole with a diameter of about 0.2mm. The reserved opening 40 will correspond to the conductive trace 20 to expose it. Then, a conductive ink (supplier JELCON; model: CH-8) is evenly printed by screen printing (100~250 mesh), and baked in a forced air oven at 80°C for 50~60 minutes, then taken out and cooled to form an electrode block 50 with a thickness of about 4~15μm and a surface resistance of less than 50 Ω/sq. The electrode block 50 will be filled into the reserved opening 40 and will form electrical contact with the conductive trace 20. The carbon black conductive ink (supplier JELCON; model: CH-8) used in this embodiment has a viscosity of about 30000±6500cp. The hole filling ability and viscosity of this ink and the aspect ratio of the aforementioned opening must be well matched to have excellent conductivity. In this comparative example, since only one reserved opening 40 is provided, the overall impedance of the conductive layer formed by the electrode block 50 filling the reserved opening 40 and the conductive trace 20 is too large (e.g., greater than 800Ω), which is not conducive to driving the colored particles in the electronic ink layer 60.

In the fourth comparative example, except that the conductive ink is diluted with a solvent (such as TETRON THINNER) so that the surface resistance of the electrode block 50 after printing is greater than 100Ω/sq (for example, 120~130Ω/sq), the other conditions are the same as those of the third comparative example. It is observed that if the surface resistance of the electrode block 50 is too high, the overall impedance of the electrode block 50 and the conductive trace 20 exceeds 1000Ω, and the electronic ink layer 60 cannot be effectively driven to change color; and after dilution, the viscosity of the carbon black conductive ink also drops significantly to below 15000 mPa•s, so that the printed material will "collapse" in the opening of the third comparative example, resulting in a circular hole-shaped defect on the electrode block 50.

Please refer to FIG. 4, which is a cross-sectional view of a display backplane with multiple reserved openings according to the eighth embodiment of the present invention. Except for the number of reserved openings, the other conditions are the same as those of the third comparative example. In this preferred embodiment, in order to ensure the electrical connection between the electrode block 50 and the conductive trace 20, each electrode block 50 can correspond to multiple reserved openings 40. As shown in FIG. 4, the electrode block 50 is filled with three reserved openings 40, 40', 40" and electrically connected to the corresponding conductive trace 20. It can be observed that even if some of the electrode blocks 50 in the reserved openings are electrically connected to the conductive traces 20, the electrode blocks 50 and the conductive traces 20 are electrically connected. In order to ensure the electrical conductivity between the electrode block 50 and the conductive trace 20, the contact impedance between each electrode block 50 and the corresponding conductive trace 20 should be less than 1×10 ^-4 Ω/cm. The embodiment of the present invention utilizes more than three reserved openings 40 with an effective diameter between 0.2-1.0 mm to form a good lap joint structure with an overall impedance less than 700Ω, preferably less than 200Ω, between the electrode block 50 and the conductive trace 20. The overall impedance of the electrode block 50 and the conductive trace 20 can be measured by a suitable instrument through the connection portion (busbar) 90.

In summary, since the structure of the display back plate 1 of the present invention can be formed only by a printing process, the conventional bonding process, the necessary adhesive material, and the thickness generated by the adhesive material can be omitted. In addition, the process of the present invention not only saves costs, but also reduces the environmental impact caused by the use of adhesive materials.

Please refer to Fig. 6, which is a flow chart of a method for manufacturing a display back plate 1 according to an embodiment of the present invention. The method for manufacturing a display back plate 1 of the present invention includes the following steps.

In step S10, a water-blocking substrate layer 10 is formed using a water-blocking substrate.

Step S20, printing a plurality of conductive traces 20 on the water-blocking substrate layer 10. The thickness of the conductive traces 20 is preferably less than 6 um to avoid visual impact of the conductive traces 20.

In step S30, the insulating layer 30 is printed on the water-blocking substrate layer 10 and the conductive traces 20, and the insulating layer 30 forms a plurality of reserved openings 40 on the conductive traces 20 to expose the conductive traces 20. The number of the reserved openings 40 is 3 or more. The thickness of the insulating layer 30 and the width of the reserved openings 40 need to be controlled to optimize the quality of the conductive slurry filling in the next step.

In step S40, a plurality of electrode blocks 50 are printed on the insulating layer 30 to fill the reserved openings 40 and electrically connect to the corresponding conductive traces 20 through the reserved openings 40. The conductive circuit formed has the characteristics of low impedance, which can well drive the colored particles in the electronic ink layer 60, and there will be no collapse or other defects of the printing process in appearance.

It should be understood that the display back panel 1 formed by the manufacturing method of the present invention has the following advantages.

First, a single material (water-blocking substrate layer 10) is used to replace two traditional sheet materials (water-blocking film and substrate), thereby saving materials and reducing the thickness of the entire display backplane.

Second, since the present invention uses the "reserved" reserved opening 40 to form an electrical connection between the conductive trace 20 and the plurality of electrode blocks 50, no additional drilling process is required. Since the drilling process is omitted, not only the cost is saved, but also the defects caused by the drilling alignment error and the environmental pollution caused by the dust generated by the drilling are avoided.

3. Since the structure of the display back plate 1 of the present invention can be formed only by a printing process, the conventional bonding process, the necessary adhesive material, and the thickness caused by the adhesive material can be omitted. In addition, the process of the present invention not only saves costs, but also reduces the environmental impact caused by the use of adhesive materials.

4. At least a portion of the implementation methods of the present invention can achieve a significant effect: significantly reducing the emission of volatile organic compounds (VOCs) and reducing dust byproducts, thus not only meeting the needs of the industry, but also meeting the net zero emission requirements of a sustainable environment.

The above is an explanation of the implementation of the present invention by means of specific embodiments. A person having ordinary knowledge in the relevant technical field can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of the present invention; any other equivalent changes or modifications that are accomplished without departing from the spirit disclosed by the present invention should be included in the following patent scope.

1: Display backplane 10: Water-blocking substrate 20, 20A, 20B, 20C, 20D, 20E, 20F: Conductive traces 30: Insulation layer 40, 40A, 40B, 40C, 40D, 40E, 40F, 40’, 40”: Reserved openings 50, 50A, 50B: Electrode blocks 60: Electronic ink layer 70: First drive electrode 80: Cover plate 90: Connector 100A, 100B, 100C, 100D, 100E, 100F, 200A, 200B, 200C, 200D, 200E: Block S10-S40: Steps

FIG1 is a cross-sectional view of a display backplane according to an embodiment of the present invention; FIG2 is a cross-sectional view of a display according to an embodiment of the present invention; FIG3 is a front perspective view of a display according to an embodiment of the present invention; FIG4 is a cross-sectional view of a display backplane with multiple reserved openings according to an embodiment of the present invention; FIG5 is a front perspective view of another display according to an embodiment of the present invention; and FIG6 is a flow chart of a method for manufacturing a display backplane according to an embodiment of the present invention.

1: Display back panel

10: Water-blocking substrate layer

20: Conductive wiring

30: Insulation layer

40: Reserve opening

50:Electrode block

Claims (9)

A backplane for an electrophoretic display comprises: a water-blocking substrate layer, comprising a PET layer and a material layer; a plurality of conductive traces arranged on the water-blocking substrate layer; an insulating layer, arranged on the water-blocking substrate layer and the conductive traces, and the insulating layer has a plurality of reserved openings to expose the conductive traces; and a plurality of electrode blocks, arranged on the insulating layer and extending to The reserved openings are electrically connected to corresponding conductive traces, wherein each of the electrode blocks corresponds to more than three reserved openings, wherein the equivalent diameter of each of the reserved openings is between 0.2-1.0 mm, and wherein the material layer includes a water-blocking coating or an aluminum layer; or the water-blocking coating includes two layers of silicon nitride or silicon oxide of different thicknesses. A backplane as described in claim 1, wherein the contact impedance between each electrode block and the corresponding conductive trace is less than 1×10 ^-4 Ω/cm, and/or the overall impedance between each electrode block and the corresponding conductive trace is less than 700Ω. The backplane as described in claim 1, wherein the glass transition temperature of the water-blocking substrate layer is greater than 80°C. The backplane as described in claim 1, wherein the conductive traces are formed by solidifying silver slurry, and the thickness of the conductive traces is less than 6μm. The backplane as described in claim 1, wherein the thickness of the insulating layer is between 3-10 μm. The backplane as described in claim 1, wherein the electrode blocks are formed from a slurry containing conductive carbon black. A backplane as described in claim 1, wherein the depth-to-width ratio of each of the reserved openings is between 10um/mm and 50um/mm. The back sheet as claimed in claim 1, wherein the water-oxygen transmission rate of the water-blocking substrate layer is between 1 g/m ² /day and 0.01 g/m ² /day. An electrophoretic display comprises: a water-blocking substrate layer, comprising a PET layer and a material layer; a plurality of conductive traces arranged on the water-blocking substrate layer; an insulating layer, arranged on the water-blocking substrate layer and the conductive traces, and the insulating layer has a plurality of reserved openings to expose the conductive traces; a plurality of electrode blocks, arranged on the insulating layer and extending into the reserved openings to be electrically connected to the corresponding conductive traces; an electrode layer; and An electronic ink layer, wherein each of the electrode blocks corresponds to more than three reserved openings, wherein the equivalent diameter of each of the reserved openings is between 0.2-1.0 mm, wherein the electronic ink layer is driven by the electrode blocks and the electrode layer to display at least one color block, and wherein the material layer includes a water-blocking coating or an aluminum layer; or the water-blocking coating includes two layers of silicon nitride or silicon oxide with different thicknesses.