WO2011027923A1

WO2011027923A1 - Reflective display device having electrochromic filter

Info

Publication number: WO2011027923A1
Application number: PCT/KR2009/005024
Authority: WO
Inventors: 김영석; 한정인; 김원근; 김영훈; 권순형
Original assignee: 에스케이 텔레콤주식회사
Priority date: 2009-09-04
Filing date: 2009-09-04
Publication date: 2011-03-10
Also published as: JP2012516466A; CN102301274A; JP5492907B2

Abstract

The present invention relates to a reflective display device having an electrochromic filter. Particularly, the invention comprises: the reflective display device; and the electrochromic filter which is attached to the reflective display device, and selectively transmits or does not transmit the light by an electrochromic material, depending on whether an electric signal is applied. Thus, since the invention employs an electrochromic element capable of switching a color mode and a black-and-white mode as a color filter of the reflective display device, the invention obtains high reflectivity and a high contrast ratio when a black-and-white image is realized even though the color filter is applied.

Description

Reflective display device with electrochromic filter

The present invention relates to a reflective display device such as an electronic paper, and more particularly, to a reflective display device having an electrochromic filter using an electrochromic device as a color filter, and more particularly, even when a color filter is applied. The implementation is for reflective displays that can achieve high reflectance and high contrast ratio.

BACKGROUND ART Conventionally, a reflective display device using an electrophoretic method, an electrochromic method, a thermal method, a two-color particle rotation method or the like has been proposed as an image display device replacing a liquid crystal (LCD). Especially, the electrophoresis type electronic paper which microencapsulates the dispersion liquid which consists of a dispersion particle and a coloring solution, and arrange | positions it between the opposing board | substrate is proposed, and the expectation is gathering.

Moreover, the electrode pair which consists of an electrode formed in one or both of the said board | substrates by sealing two or more types of particle | grains from which a color and a charging characteristic differ at least between two transparent board | substrates at least without using the dispersion liquid mentioned above recently. There has been proposed a dry electronic paper which imparts an electric field to the particles, and which moves the particles by coulomb force to display an image.

The cell structure of the dry electronic paper display device is shown in FIG. 1, and as shown here, the structure includes upper and

lower substrates

160 and 110 formed of plastic or glass, and upper and lower substrates 160. Upper and

lower electrodes

170 and 120 formed of a transparent electrode (ITO) to apply a driving voltage of the device on the substrate 110, a partition wall 130 separating the cell from the cell, and a black present between the two electrodes. It consists of positive (+) charged particles 140 and white negative (-) charged particles (150).

Such dry electronic paper display devices are reflective displays, and generally display color images using color filters or color particles. 2 and 3 are cross-sectional views showing the structure of an electronic paper display device using a conventional RGB color filter and RGB color particles, respectively.

First, Figure 2 is a cross-sectional view showing the structure of an electronic paper display device using a conventional RGB color filter. As shown here, the substrate of the electrophoretic display device using the color filter is a color filter of red (R), green (G), blue (B) formed on the upper substrate 221 to implement color A partition 223 which distinguishes between the 220 and the RGB cell 227 and serves as a light blocking function, and

transparent electrodes

224 and 225 for applying a voltage to the cell 227. The appearance of the color image by such a structure consists of a mixture of the light passing through the color filters 220 of red, green, and blue arranged adjacently.

3 is a cross-sectional view showing the structure of a conventional electronic paper display using RGB color particles. As shown here, such an electronic paper display device distinguishes between color particles 240 of red (R), green (G), and blue (B) and RGB cells included in each cell to implement color. A partition wall that serves as light blocking and black charged particles 236, which are light absorbing materials, are provided. The electrophoretic display device implements color using electrophoretic color particles 240 of red (R), green (G), and blue (B) included in each cell in order to implement color. That is, when a voltage is applied to the counter electrode, the color particles emerge or fall, thereby reflecting the light of the color of the extraordinary color particles, and the reflected light is mixed to display colors.

As described above, in the case of a conventional reflective display device or an electronic paper, 1) a color filter or 2) a color cell structure is used to implement color. However, in the case of using the 1) color filter, the color filter can be made by an existing process, and thus it is easy to apply. However, the color filter has a low reflectance and a low contrast ratio. In addition, 2) in the case of using the color cell structure, a process of manufacturing a color filter is not required, but a process of making and injecting color balls or color particles in each pixel is difficult, and thus it is difficult to implement. However, even with color particles, low reflectance and low contrast ratio are unavoidable.

That is, in the conventional color implementation method, low reflectance and low contrast ratio are inevitable in the color screen. In addition, in the case of electronic paper mainly providing a black and white screen, the black and white implementation in the panel to which the color filter is applied has a serious problem of having a very low reflectance and contrast ratio compared to the black and white panel to which the color filter is not applied.

The present invention for solving the above problems, as a color filter of the reflective display device, using an electrochromic device that can switch the color mode and black and white mode, even when applying a color filter high reflectance and high contrast ratio when implementing a black and white image It aims to obtain a contrast ratio.

According to the present invention, there is provided a reflective display device including an electrochromic filter, including: a reflective display device; And an electrochromic filter attached to the reflective display device and selectively transmitting or non-transmitting light by an electrochromic material depending on whether an electric signal is applied or not.

Here, the reflective display device is preferably an electronic paper for displaying an image by the movement of particles located between the opposite electrodes, the reflective display device, the lower substrate; A lower electrode formed on the lower substrate; An upper electrode disposed to face the lower electrode; Barrier ribs that divide a pixel between the lower electrode and the upper electrode to form a plurality of pixel spaces; And a plurality of particles encapsulated in the pixel space.

The electrochromic filter may be an electrochromic device including a transparent electrode and an electrochromic material layer. The electrochromic filter may include a front substrate; A first electrode formed on the front substrate; A second electrode disposed to face the first electrode; An electrochromic material existing between the first electrode and the second electrode; And an electrolyte filled between the electrodes.

In addition, the reflective display device may have a plurality of pixel spaces, and the electrochromic filter may be a plurality of electrochromic filters each including an electrochromic material that may be converted into a different color corresponding to the pixel space. Do.

On the other hand, another embodiment of the present invention, a reflective display device; And an electrochromic filter attached to the reflective display device and selectively transmitting or non-transmissive light by an electrochromic material depending on whether an electric signal is applied or not. The reflective display device includes: Lower substrate; A lower electrode formed on the lower substrate; An upper electrode disposed to face the lower electrode; Barrier ribs that divide a pixel between the lower electrode and the upper electrode to form a plurality of pixel spaces; And a plurality of particles encapsulated in the pixel space, wherein the electrochromic filter comprises: a front substrate; A first electrode formed on the front substrate; A second electrode disposed to face the first electrode; An electrochromic material existing between the first electrode and the second electrode; And an electrolyte filled between the electrodes. The reflective display device may include an electrochromic filter.

The second electrode of the electrochromic filter may be stacked on the upper electrode of the reflective display device, and the electrochromic filter may be attached to the reflective display device. An insulating layer may be included between the second electrodes of the electrochromic filter.

In addition, the electrochromic filter may be a plurality of electrochromic filters each including an electrochromic material which may be converted into different colors corresponding to the pixel space.

Specific details of other embodiments are included in the detailed description and the drawings.

1 is a perspective view showing a cell structure of a dry electronic paper which is a conventional reflective display device,

2 is a cross-sectional view showing the structure of an electronic paper display device using a conventional RGB color filter.

3 is a cross-sectional view showing the structure of a conventional electronic paper display device using RGB color particles,

4 is a cross-sectional view illustrating a structure of a reflective display device equipped with an electrochromic filter according to an exemplary embodiment of the present invention.

5 is a perspective view showing the structure of an electrochromic device used as a color filter according to the present invention;

Figure 6 is a schematic diagram for explaining that the electrochromic filter according to the present invention is in a transparent state,

7 is a schematic view for explaining that the electrochromic filter according to the present invention is in an opaque state,

8 is a cross-sectional view for explaining a state in which the electrochromic filter is switched to the monochrome mode in the reflective display device according to the present invention;

9 is a cross-sectional view for explaining a state in which the electrochromic filter is switched to the color mode in the reflective display device according to the present invention.

Hereinafter, one preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. The invention may be better understood by the following examples, which are intended for purposes of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

4 is a cross-sectional view showing the structure of a reflective display device equipped with an electrochromic filter according to an exemplary embodiment of the present invention. As shown here, the present invention provides a reflective display device 10 and an electrochromic filter ( 20 is a reflective display device 1 equipped with an electrochromic filter.

In the present specification, the reflective display apparatus 10 may include, for example, an electrophoretic dry type electronic paper displaying an image by movement of particles positioned between electrodes facing each other, and the electrochromic filter 20. Means that the electrochromic device (ECD), in which the color of the electrochromic material is changed by electric redox reaction according to the application of the electric field and the light transmission characteristic is changed, is used as a filter for color realization. . The present invention, in which the electrochromic filter 20 is attached to the reflective display device 10, uses an electrochromic device in place of a conventional color filter in the reflective display device.

Reflective displays such as electronic paper use only external light, so it is important to maximize light efficiency. When color is implemented using a color filter, a dark screen and a low contrast ratio are obtained due to a decrease in transmittance. In addition, even when implementing a black and white screen has a low contrast ratio compared to the structure without using a color filter, it is disadvantageous to produce a color in an e-book mainly using a black and white screen. Accordingly, the present invention is characterized by having a variable color filter using an electrochromic device as a filter so that the color can be represented only in a color mode that requires color implementation.

To this end, the electrochromic filter 20 according to the present invention should be to selectively transmit or non-transmissive light by the electrochromic material in accordance with the presence or absence of the electrical signal, attached to the reflective display device 10 is coupled Should be. In particular, the reflective display device 10 includes a lower substrate 12 without an upper substrate as shown in FIG. 1; A lower electrode 11 formed on the lower substrate; An upper electrode 13 disposed to face the lower electrode; Barrier ribs 14 for dividing pixels between the lower and upper electrodes to form a plurality of pixel spaces; And a plurality of particles 15 encapsulated in the pixel space. In addition, the electrochromic filter 20 is a front substrate 21, without the back substrate as shown in Figure 1; A first electrode 22 formed on the front substrate; A second electrode 23 disposed to face the first electrode; An electrochromic material 24 present between the first electrode and the second electrode; And an electrolyte 25 filled between the electrodes.

According to the present invention, the second electrode 23 of the electrochromic filter 20 is stacked on the upper electrode 13 of the reflective display device 10, so that the electrochromic filter 20 is the reflective display device. It is attached to (10), which has a difficulty in construction that cannot be conceived by simply combining conventional electrochromic elements and electronic paper. Attaching and combining the electrochromic filter 20 and the reflective display device 10 may be any method known in the art.

Furthermore, in order to separately drive the electrochromic filter 20 and the reflective display device 10 according to the present invention, the upper electrode 13 and the electrochromic filter 20 of the reflective display device 10 are separated. The insulating layer 30 may be further included between the second electrodes 23, and the insulating layer 30 may be made of a transparent material.

In addition, in FIG. 1, the upper electrode 13 of the reflective display device 10 and the second electrode 23 of the electrochromic filter 20 are respectively shown to be separated to apply different voltages. However, the present invention also includes a cylindrical electrode in which the upper electrode 13 of the reflective display device 10 and the second electrode 23 of the electrochromic filter 20 are integrated into one.

5 is a perspective view showing the structure of an electrochromic device used as a color filter according to the present invention. As shown here, the electrochromic filter 20 according to the present invention includes a transparent electrode and an electrochromic material layer. It may be an electrochromic device. That is, the electrochromic filter 20 according to the present invention, the front substrate 21; A first electrode 22 formed on the front substrate; A rear substrate 26 disposed to face the front substrate; A second electrode 23 formed in a direction toward the front substrate from the rear substrate surface; An electrochromic material 24 formed on the second electrode; And an electrolyte 25 filled between the electrodes. Here, in the case of the electrochromic device in which the electrochromic material 24 is distributed in the electrolyte 25, the electrochromic material 24 will be dispersed in the electrolyte 25 unlike FIG. 1.

The electrochromic device is a device using the principle that the oxidation / reduction reaction proceeds by the flow of electric current when electric field is applied, and the color of the electrochromic material 24 is changed. In addition, US Pat. No. 6,605,239 describes electronic paper using an electrochromic material. However, all of the conventional electronic paper using the electrochromic material is used as the cell inside particles for displaying the image, and thus, fundamentally different from the present invention using the electrochromic device as a color filter.

6 and 7 are schematic views for explaining that the electrochromic filter 20 according to the present invention is in a transparent state and an opaque state, respectively, which is the front substrate 21 described above; A first electrode 22; Electrolyte 25; Electrochromic material 24; Second electrode 23; Back substrate 26; shows a stacked structure sequentially, an ion storage layer having a titanium oxide or the like in order to supply the ions insufficient to the electrolyte 25 between the first electrode 22 and the electrolyte 25 ( 29) may be further included.

Thus, in a state where power is not applied to the first and

second electrodes

22 and 23, most of the visible light and the infrared light are transmitted, and part of the light is reflected (FIG. 6). When power is applied to the first and

second electrodes

22 and 23 in this state, the electrochromic material 24 is brought into an ion state by the electrolyte 25, which is the first electrode and the first electrode. By the voltage applied to the two

electrodes

22 and 23, a specific color is reflected and most of the visible and infrared rays are transmitted and only a part thereof is transmitted.

Here, the electrochromic material 24 may be divided into an inorganic electrochromic material and an organic electrochromic material. Representative inorganic electrochromic materials include WO ₃ , NiOxHy, Nb ₂ O ₅ , TiO ₂ , MoO _3, and the like, and organic electrochromic materials include viologen, phenothiazine, and polyaniline. When the discoloration process is displayed for WO ₃ , which is one of the electrochromic materials, it can be expressed as in [Scheme 1] below.

Scheme 1

WO ₃ (bleached, transparent) + xe ^_ + xM ⁺ ⇔ MxWO ₃ (dark blur colored, dark blue)

In Reaction Scheme 1, M represents lithium, proton, calcium, and the like, and typically lithium is most used. Lithium ions react with WO ₃ to have an electrochromic effect that turns blue as above. As such, the solid electrolyte may be used to supply lithium ions.

In addition, the present invention can use the electrochromic material 24 that can implement a variety of colors, depending on the type of the electrochromic material 24 and the type of the functional group substituted, according to the present invention is the reflective display device 10 has a plurality of pixel spaces, and the electrochromic filter 20 includes a plurality of electrochromic filters each including an electrochromic material 24 which can be converted into different colors corresponding to the pixel space. 20).

In addition, a liquid electrolyte and a solid polymer electrolyte may be used as the electrolyte 25, and the solid polymer electrolyte is a material capable of transferring ions in a solid state, and thus is environmentally friendly since there is no problem such as leakage of liquid when the device is manufactured. It is possible to make it thin in any shape and has the advantage that it can be manufactured. Examples of the liquid electrolyte are 1M LiOH aqueous solution, 1M LiClO ₄ aqueous solution, 1M KOH aqueous solution, and inorganic hydrates include Ta ₂ O ₅ ㆍ 3.92H ₂ O, Sb ₂ O ₅ ㆍ 4H ₂ O, and the like. Poly-AMPS, Poly (VAP), Modified PEO / LiCF ₃ SO ₃ may be used as the polymer electrolyte.

8 and 9 are cross-sectional views illustrating a state in which the electrochromic filter is switched to a black and white mode and a color mode in the reflective display device according to the present invention, respectively.

As described above, the electrochromic layer is formed on the reflective display panel or the electronic paper panel instead of the existing general color filter, and when the black and white image is realized, the electrochromic layer is made transparent so that the color is required. The color change is realized by developing an electrochromic layer.

In the case of using the conventional RGB filter, there is a problem that the light reflectance is greatly reduced (a level of 30%) in the reflection type. In the present invention, the electrochromic device can be used as a color filter to switch to the black and white mode. The present invention combines a conventional electrochromic device and a reflective display device using electrophoresis or liquid powder into one, thereby realizing a color having a higher contrast ratio than the contrast ratio when only one of them is used.

That is, according to the present invention, the electrochromic filter 20 selectively transmits or not transmits light as shown in FIGS. 8 and 9 to switch between the black and white mode (FIG. 8) and the color mode (FIG. 9). As a result, it is possible to obtain high reflectance and high contrast ratio when implementing black and white images while implementing color.

On the other hand, while the present invention has been shown and described with respect to certain preferred embodiments, the invention is variously modified and modified without departing from the technical features or fields of the invention provided by the claims below It will be apparent to those skilled in the art that such changes can be made.

According to the present invention, as a color filter of the reflective display device, by using an electrochromic device capable of switching the color mode and the black and white mode, even if a color filter is applied, high reflectance and high contrast ratio when implementing a black and white image (contrast ratio) ) Is effective.

That is, the present invention uses an electrochromic layer as a color filter instead of a conventional PR type color filter to improve reflection efficiency while realizing color in a reflective display device such as electronic paper. By using this, it is possible to provide electronic paper capable of switching between black and white mode and color mode in accordance with an image.

Claims

Reflective display devices; And,

An electrochromic filter attached to the reflective display device, the electrochromic filter selectively transmitting or not transmitting light by an electrochromic material depending on whether an electric signal is applied or not; Device.
The reflective display device according to claim 1, wherein the reflective display device is an electronic paper for displaying an image by movement of particles positioned between electrodes facing each other.
The display device of claim 1, wherein the reflective display device comprises:

Lower substrate;

A lower electrode formed on the lower substrate;

An upper electrode disposed to face the lower electrode;

Barrier ribs that divide a pixel between the lower electrode and the upper electrode to form a plurality of pixel spaces; And

Reflective display device having an electrochromic filter comprising a; a plurality of particles encapsulated in the pixel space.
The reflective display device of claim 1, wherein the electrochromic filter is an electrochromic device including a transparent electrode and an electrochromic material layer.
The method of claim 1, wherein the electrochromic filter,

Front substrate;

A first electrode formed on the front substrate;

A second electrode disposed to face the first electrode;

An electrochromic material existing between the first electrode and the second electrode; And,

Electrolyte filled between the electrode; Reflective display device having an electrochromic filter comprising a.
The electrochromic display device of claim 1, wherein the reflective display device has a plurality of pixel spaces, and the electrochromic filter includes a plurality of electrochromic materials each of which can be converted into a different color corresponding to the pixel space. Reflective display device having an electrochromic filter, characterized in that the filter.
Reflective display devices; And,

And an electrochromic filter attached to the reflective display device to selectively transmit or not transmit light by an electrochromic material depending on whether an electric signal is applied or not.

The reflective display device includes a lower substrate; A lower electrode formed on the lower substrate; An upper electrode disposed to face the lower electrode; Barrier ribs that divide a pixel between the lower electrode and the upper electrode to form a plurality of pixel spaces; And a plurality of particles encapsulated in the pixel space.

The electrochromic filter may include a front substrate; A first electrode formed on the front substrate; A second electrode disposed to face the first electrode; An electrochromic material existing between the first electrode and the second electrode; And an electrolyte filled between the electrodes.
The electrochromic filter of claim 7, wherein a second electrode of the electrochromic filter is stacked on an upper electrode of the reflective display device, and the electrochromic filter is attached to the reflective display device. Reflective display device.
The reflective display device of claim 8, wherein an insulating layer is included between the upper electrode of the reflective display device and the second electrode of the electrochromic filter.
8. The reflective type electrochromic filter of claim 7, wherein the electrochromic filter comprises a plurality of electrochromic filters each comprising an electrochromic material capable of being converted into a different color corresponding to the pixel space. Display device.