KR101198820B1 - electronic ink and display device using thereof - Google Patents

Abstract

The present invention relates to an electronic ink and an image display apparatus using the same, which can freely adjust various intermediate gray scales in addition to the maximum and minimum gray scales commonly implemented.

To this end, the present invention provides encapsulated inorganic or organic fluids; At least one type of particle each of which has an absolute value of different charge value and is electrophoretically immersed in the encapsulated fluid or charged with a different size and electrophoretically immersed in the encapsulated fluid. An electronic ink layer comprising: a film of a binder immersed in a plurality of electron inks; It provides an image display device comprising an upper, a lower transparent substrate arranged to face each other with the electronic ink layer interposed therebetween with the upper and lower transparent electrodes interposed therebetween.

Electron ink, electrophoresis, gradation, particle, charge value, size

Description

Electronic ink and image display device using same             

1 is a cross-sectional view of an image display apparatus using a general electronic ink.

Figures 2a to 2c are circuit diagrams for the electrophoretic state of a typical electronic ink, respectively.

3 is a cross-sectional view of an image display apparatus using an electronic ink according to a first embodiment of the present invention.

4A to 4D are circuit diagrams of an electrophoretic state of an electronic ink according to a first embodiment of the present invention, respectively.

5 is a cross-sectional view of an image display apparatus using an electronic ink according to a second embodiment of the present invention.

6A to 6D are circuit diagrams of an electrophoretic state of an electronic ink according to a second embodiment of the present invention, respectively.

<Description of the symbols for the main parts of the drawings>

52,54: upper and lower transparent substrates 56,58: upper and lower transparent electrodes

60: electron ink layer 62: film                 

64: ink capsule 66: fluid

70a, 70b: Particles 72a, 72b: Part 1 Particles

74a, 74b: Part 2 particles

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic ink including at least one particle immersed in a predetermined fluid encapsulated in an electrically charged state and electrophores by an external electric field, and to an image display apparatus using the same. The present invention relates to an electronic ink capable of freely adjusting various intermediate gray scales in addition to the maximum and minimum gray scales, and an image display apparatus using the same.

In recent years, as the society enters a full-scale information age, a display field for processing and displaying a large amount of information is rapidly developing.

In response to this, various flat panel display devices (FPDs) with excellent characteristics such as thinness, light weight, and low power consumption are introduced to replace the existing cathode ray tube (CRT). For example, Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Field Emission Display (FED), Electroluminescence Display (ELD), etc. Can be mentioned.                         

On the other hand, the recently introduced so-called Digital Paper Display (DPD) is much cheaper to produce than conventional flat panel displays and requires no additional backlighting, so it can be driven with very little energy. This broad and most important feature is the ability to bend repeatedly like a paper without changing resolution and contrast. Currently, it is applied to portable computers, electronic newspapers, or smart cards. It is expected to be the next generation display device that will widely replace traditional print media such as magazines and magazines.

The driving principle of such a digital paper display is simply to use a system according to the electrophoretic state of the electron ink, which is immersed so that at least one charged particle can float in an encapsulated fluid. In this case, an electric field is applied to artificially electrophoretic particles to express two contrasting gradations of black and white.

More specifically, FIG. 1 is a cross-sectional view schematically illustrating a structure of an image display apparatus using a general electronic ink, such as a conventional digital paper display, and includes upper and lower transparent substrates 2 and 4 made of a transparent insulating material of glass or plastic. ) Face each other, and the upper and lower transparent electrodes 6 and 8 made of transparent conductive materials are formed on the surfaces facing each other.

In addition, an electron ink layer 10 is interposed between the upper and lower transparent electrodes 6 and 8, and the ink encapsulated microcapsules 14 are dispersed in a film 12 of a binder made of a polymer or the like. Each ink capsule 14 is filled with an inorganic or organic fluid 16 which is transparent or colored in a predetermined color and has at least one particle 20 having a predetermined charge therein so as to float therein. It is immersed.

In this case, the at least one particle 20 may be divided into, for example, a positively charged white first type particle 22 and a negatively charged black second type particle 24, and the upper and lower transparent electrodes ( Electrophoresis is performed by the electric field between 6 and 8) to display white and black gradations, respectively.

2A to 2C are circuit diagrams showing the different electrophoretic states of the electron inks. First, as shown in FIG. 2A, the upper transparent electrode 6 is charged at −V and the lower transparent electrode 8 is charged at + V. In this case, the positively charged white first type particle 22 is drawn toward the upper transparent electrode 6 while the negatively charged black second type particle 24 is concentrated in the lower transparent electrode 8 direction. As a result, when viewed from outside the upper transparent electrode 6, white gradation is expressed. In this case, ± V is a voltage value of a predetermined magnitude, respectively, indicating a degree sufficient to electrophorize the first and second type particles 22 and 24.

On the contrary, in FIG. 2B, the upper transparent electrode 6 is charged to + V, and the lower transparent electrode 8 is charged to -V. As a result, the second type particle 24 having black color with negative charge is upper transparent. The first type particle 22 of positive charge is concentrated in the direction of the lower transparent electrode 8 while being concentrated in the direction of the electrode 6, and as a result, black gradations appear to the outside.

And awards. When there is no electric field difference between the lower transparent electrodes 6 and 8 or is so weak that it does not affect the electrophoresis of the particle 20, as shown in FIG. 2C, the first and second type particles 22 and 24 are formed. They are slowly driven to the center boundary by the attraction force of each other, and as a result, the gray gradation appears to the outside.

Thus, the electrophoretic state of the general electronic ink has two modes, white and black, respectively, shown in FIGS. 2A and 2B except for FIG. 2C which maintains a natural neutral state because there is no potential difference between the upper and lower transparent electrodes 6 and 8. Restriction, there is no way to artificially express various gray scales therebetween.

That is, the gray level that can be artificially expressed using a general electronic ink is limited to the maximum and minimum gray levels depending on the intrinsic color of each particle 20. Particularly, the particle 20 also has negative and positive charges with the same absolute value. In other words, it is difficult to exist in addition to the two kinds of, and thus, the conventional electronic ink has a disadvantage in that it is impossible to artificially control and express the mid-tones of various various shades therebetween in addition to the two contrasting maximum and minimum gray scales.

Accordingly, the present invention provides an electronic ink and an image display apparatus using the same, which can freely adjust various intermediate gray scales in addition to the maximum and minimum gray scales that can be generally expressed to solve the above problems. There is a purpose.

For example, the present invention can artificially control and express gray tones of various various shades in addition to white and black, which are different from the conventional ones, while using two types of particles, negative and positively charged white and black, respectively. It is to provide an electronic ink, and furthermore to provide an image display apparatus using the same.

In order to achieve the above object, the present invention comprises an inorganic or organic fluid encapsulated to achieve the above object; Each size is the same, the absolute value of each charge amount is different from each other, and provides an electronic ink, characterized in that it comprises a plurality of particles immersed in the encapsulated fluid to be electrophoretic.
In this case, each of the plurality of particles has a unique color, and is divided into first and second types that are positively or negatively charged, and the first and second type particles are white and black, respectively.
The first type particle is made of titanium oxide, and the second type particle is carbon-based.
And, the electronic ink layer made of a binder film containing a plurality of the electronic ink dispersion; Upper and lower transparent arranged to face each other with the electronic ink layer interposed therebetween with the upper and lower transparent electrodes on the opposite side respectively An image display apparatus comprising a substrate, wherein the electron ink layer comprises a binder film containing a plurality of electron inks; The image display apparatus includes upper and lower transparent substrates arranged to face each other with the electronic ink layer interposed therebetween with the upper and lower transparent electrodes interposed therebetween. The present invention will be described in more detail with reference to.

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3 and 5 are cross-sectional views illustrating the structure of the electronic ink and the image display apparatus using the same according to the embodiments of the present invention, respectively, for convenience of explanation. Precedes the description.

As shown, an image display apparatus using an electronic ink according to the present invention has a pair of images each having an upper and lower transparent electrodes 56 and 58 interposed therebetween with a middle electronic ink layer 60 therebetween. The lower transparent substrates 52 and 54 are arranged face to face.

More specifically, first, the pair of upper and lower transparent substrates 52 and 54 may each be made of a transparent insulating material such as glass or plastic, preferably plastic that can be bent or bent, and as a result, The image display device according to this may be a so-called digital paper display.

In addition, the upper and lower transparent electrodes 56 and 58 formed on the surfaces of the upper and lower transparent substrates 52 and 54 facing each other may be transparent conductive materials, typically, indium tin oxide (ITO) or the like. It may be made of other transparent conductive polymer material and preferably has a thickness of about several thousand micrometers.

Next, the electron ink layer 60 interposed between the upper and lower transparent electrodes 56 and 58 has a form in which microencapsulated ink capsules 64 are dispersed and contained in a film 62 of a binder made of a polymer. The film 62 of the binder fixes the position of each ink capsule 64 and at the same time serves as a crosslinking agent for the electrical and physical separation, specifically, water-soluble, water-dispersed, fat-soluble, thermosetting, thermoplastic Dielectric materials such as polymers or UV cured or irradiated polymers can be used.

Also, the film 62 of such a binder is screen printed on the upper and lower transparent electrodes 56 and 58 on the upper and lower transparent substrates 52 and 54 in a state in which the ink capsule 64 to be described later is dispersed. It may be applied by a roll coating or a spin coating method, and may be completed through a curing step of heating at a high temperature of about 100 to 200 ° C. for several minutes.

In addition, the ink capsule 64 dispersed therein is filled with a predetermined organic or inorganic fluid 66 therein, for example, having a diameter of about 150 to 200 μm, and within the predetermined fluid 66. At least one particle 70a, 70b electrically charged is immersed, respectively.

At this time, the ink capsule 64 is mainly made of an organic material and the fluid 66 filled therein is used as an inorganic material, but depending on the purpose, the fluid and particles immersed therein in place of the ink capsule 64 ( It is also possible to form a partition wall that separates 70a and 70b for each pixel. The fluid 66 filled in the ink capsule 64 is not particularly limited as long as it exhibits high resistivity while maintaining a viscosity sufficient to freely allow electrophoresis of each particle 70a or 70b. Two or more mixed fluids are possible and, depending on the purpose, it is also possible to color them in any color, such as transparent or suspension.

Accordingly, the image display device according to the present invention controls the electric field between the upper and lower transparent electrodes 56 and 58 to electrophores each of at least one type of particles 70a and 70b immersed in the capsule 64. An image is expressed using the gradation difference.

In this case, in particular, the present invention provides the ink capsule 64, strictly at least one particle 70a, 70b, to artificially freely adjust various intermediate gray scales in addition to the maximum and minimum gray scales commonly implemented. ) Each has different physical properties from the prior art, which may be divided into several embodiments, so that each will be described separately.

1st Example

First, in the electronic ink according to the first embodiment of the present invention, at least one charged particle 70a is immersed into the fluid 66 filled in each ink capsule 64, as shown in FIG. These particles 70a are characterized in that their absolute values have different charge values.

More specifically, the particles 70a may be classified into a first type particle 72a having a large positive charge amount and a second type particle 74a having a negative charge amount. The two kinds of particles 72a, 74a are respectively -1, -2, -3 within the range of negative and positive. And +1, +2, +3... As shown in the figure, the absolute values have different charges.

In this case, the first and second type particles 72a and 74a may have different colors, respectively. For example, the first type particle 72a may use a white titanium dioxide material and the second type particle. The black carbon series 74a may be used, and each may have a sphere shape and pigment particles may be used for faster and more uniform electrophoresis in the fluid 66.

The total amount of charges of these first and second type particles 72a and 74a is preferably maintained at zero.

In other words, in the electronic ink according to the first embodiment of the present invention, the shape and the material of the first and second type particles 72a and 74a are not particularly limited, but -1, -2, -3. To +1, +2, +3... As shown in Fig. 2, the absolute values of the charges are different from each other in the negative and positive ranges. As a result, the maximum and minimum values of white and black are appropriately controlled by appropriately adjusting the electric field size between the lower transparent electrodes 56 and 58, respectively. In addition to gradation, various intermediate gradations can be expressed in between.

This will be described with reference to FIG. 3 above with reference to the circuit diagrams of FIGS. 4A to 4D respectively illustrating the electrophoretic states of the electronic ink according to the first embodiment of the present invention.

First, FIG. 4A illustrates a state in which white, which is the maximum gray level of the electronic ink according to the present invention, is implemented, and a negative voltage -V (-V << 0) sufficiently small is applied to the upper transparent electrode 56, and the lower transparent electrode ( 58, a sufficiently large positive voltage + V (+ V >> 0) is applied. As a result, when the first type particles 72a are all biased toward the upper transparent electrode 56 and the second type particles 74a are all biased toward the lower transparent electrode 58, when viewed from the outside of the upper transparent electrode 56. White, the maximum gradation, is realized.

Next, FIG. 4B is a state in which black, which is the minimum gray level of the electronic ink according to the present invention, is implemented. On the contrary, a sufficiently large positive voltage + V is applied to the upper transparent electrode 56 while the lower transparent electrode 58 is sufficiently applied. A small negative voltage -V is applied, so that the first type particles 72a are all biased toward the lower transparent electrode 58 and the second type particle 74a is all biased toward the upper transparent electrode 56. As a result, black, which is the minimum gray scale, is realized externally.

4C illustrates a case in which the electric field difference between the upper and lower transparent electrodes 56 and 58 is little or extremely weak, and the first and second type particles 72a and 74a are formed inside the ink capsule 64 by the attraction of each other. Are concentrated in approximately the center portion of, resulting in the first gray, which is a halftone outside.

Subsequently, in FIG. 4D, a gray scale that is darker than white, which is the maximum gray scale of FIG. 4A, but lighter than the first gray, which is the middle gray scale of FIG. 4C, is implemented, and -Vg having an absolute value smaller than -V is applied to the upper transparent electrode 56. Positive voltage + Vg smaller than + V is applied to the lower transparent electrode 58. As a result, only a part of the first type particle 72a is biased toward the upper transparent electrode 56 side, while only a part of the second type particle 74a is biased toward the lower transparent electrode 58 side, and as a result, some of the particles are still ink capsules. (74) It is mixed in the central part of the inside, so that the second gray gradation that is relatively brighter than the first gray and darker than the white which is the maximum gradation is realized outside.

In this case, considering the various resistance components between the upper and lower transparent electrodes 56 and 58, that is, the film 62, the capsule 64, the fluid 66, and the like, ± V and ± Vg are difficult to quantify. The minimum size of electrophoresis of both the first and second type particles 72a, 74a, respectively, + Vg is in the range of 0 <+ Vg <+ V, -Vg is -V <-Vg < It is in the range of 0.

Therefore, although not all specific forms are shown in separate drawings, the charge values of the first and second type particles 72a and 74a may be variously adjusted, and the size of ± Vg may be appropriately adjusted within the permitted range, respectively. At the same time, one of ordinary skill in the art will readily realize that a wider range of gray halftones between white and black, which is the maximum and minimum grayscales, can be realized through a simple application such as changing ± Vg applied to the upper and lower transparent electrodes 56 and 58, respectively. Could be.

Second Example

The electronic ink according to the second embodiment of the present invention is shown in FIG. 5, mainly to explain the differences from the first embodiment in order to avoid unnecessary duplication, and to facilitate the distinction of the particles 70b and the first And the identification code of b was added to the reference numerals of the type 2 particles (72b, 74b), respectively, and the same reference numerals have been given to the same parts that play the same role as the above description.

As shown therein, the particles 70b of the electronic ink according to the second embodiment of the present invention are the first type particle 72b of positive charge having a white color and the second particle 74b of negative charge having a black color, respectively. In particular, these first and second type particles (72b, 74b) is characterized in that they have different sizes.

In this case, if the first and second type particles 72b and 74b have the same titanium oxide and carbonaceous materials, respectively, they mean different sizes and weights. It implements various gradations other than white.

6A to 6D show different electrophoretic states of the electro-ink according to the second embodiment of the present invention. First, FIG. 6A is a state in which white, the maximum gray scale, is implemented.

In this case, a negative voltage −V ′ (−V ′ << 0) is applied to the upper transparent electrode 56, which is small enough to electrophorize all the first type particles 72b, and the lower transparent electrode 58. ) Is applied a positive voltage + V '(+ V' >> 0) that is large enough to electrophorize all of the second type particles 74b, so that all of the first type particles 72b are The particles of the second type 74b are all concentrated in the direction of the lower transparent electrode 58 while being driven toward the transparent electrode 56.

As a result, white, which is the maximum gray scale, appears to the outside.

On the contrary, FIG. 6B illustrates a state in which black, which is the minimum gray scale, is implemented, and a positive voltage + V 'large enough to electrophorize all the second type particles 74b is applied to the upper transparent electrode 56, and the lower transparent A negative voltage -V 'small enough to electrophores all the first type particles 72b is applied to the electrode 58, so that all the second type particles 74b are directed toward the upper transparent electrode 56. While the first type particles 72b are all concentrated in the direction of the lower transparent electrode 58.

As a result, black, which is the minimum gray scale, appears.

Next, FIG. 6C illustrates a case in which the electric field difference between the upper and lower transparent electrodes 56 and 58 is no or extremely weak. In this case, the first and second type particles 72b and 74b are formed by the ink capsules due to mutual attraction. 64) It is concentrated to approximately the middle part of the inside, and as a result, the first gray, which is a halftone, appears to the outside.

6D is another state in which darker than white, which is the maximum gray level, but lighter than the first gray color, is implemented, in which case the upper transparent electrode 56 has a -Vg 'voltage smaller than 0 and greater than -V' of the minimum gray scale. This voltage is applied to the lower transparent electrode 58 with a voltage of + Vg 'greater than zero and smaller than + V' of the maximum gray scale.

Therefore, only a relatively small portion of the first type particle 72b is electrophoresed toward the upper transparent electrode 56, while the remaining relatively large portion remains in the center of the ink capsule 64 without being dragged. In addition, the second type particles 74b are also electrophoresed in the direction of the lower transparent electrode 58, while some of the relatively small size remain in the center of the ink capsule 64.

Therefore, another halftone appears darker than white, which is the maximum grayscale, but lighter than the first gray.

At this time, considering the various resistance components between the upper and lower transparent electrodes 56 and 58 as in the first embodiment, it is difficult to quantify ± V 'and ± Vg', but ± V 'is the first size having a different size. And a minimum voltage capable of electrophoretic both type II particles 72b and 74b, + Vg 'is within the range of 0 <+ Vg' <+ V ', and -Vg' is -V '. It exists in the range of <-Vg '<0.

Accordingly, the size of the first and second type particles 72b and 74b are variously adjusted, and the size of ± Vg 'is appropriately adjusted within the allowable range, respectively, and the upper and lower transparent electrodes 56 and 58 are respectively A simple application such as changing the ± Vg 'applied to can realize a variety of gray tones.

Furthermore, another form in which the first and second embodiments of the present invention are applied together is also possible, although the first and second type particles have absolute values within the negative and positive ranges, respectively, although not shown in the drawings. It is possible to have a different amount of charge and at the same time different sizes, and as a result, it will be readily apparent to those skilled in the art that more various halftones are implemented.

As described above, in addition to the maximum and minimum gray scales, the electronic ink according to the present invention can implement a midtone of more various shades therebetween, and thus, there is an advantage in that a variety of images can be expressed.

Claims (12)

Encapsulated inorganic or organic fluids; Wherein each size is the same, and the absolute value of each charge amount is different from each other, and includes a plurality of particles immersed in the encapsulated fluid so as to be electrophoretic. The method of claim 1, The plurality of particles each have a unique color, the electronic ink, characterized in that divided into first and second types of positive or negative charge. 3. The method of claim 2, The first and second type particles are white, black, the electronic ink, characterized in that.  The method of claim 3, The first type particle is a titanium oxide material, the second type particle is an electronic ink, characterized in that the carbon-based. delete An image display apparatus using the electronic ink according to any one of claims 1 to 4, An electron ink layer comprising a binder film in which the electron ink is dispersed and contained in a number; And upper and lower transparent substrates arranged to face each other with the upper and lower transparent electrodes interposed therebetween with the electronic ink layers interposed therebetween. delete delete delete delete delete delete

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