News Column

Patent Application Titled "Light-Controlling Device and Method of Manufacturing the Same" Published Online

July 3, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors SEONG, MiRyn (Paju-si, KR); NOH, YoungHoon (Paju-si, KR); LEE, MoonSun (Sejong, KR), filed on December 9, 2013, was made available online on June 19, 2014.

The assignee for this patent application is Lg Display Co., Ltd.

Reporters obtained the following quote from the background information supplied by the inventors: "The present invention relates to a light-controlling device, and more particularly, to a light-controlling device with increased light transmittance and a shielding rate, and method of increasing the light transmittance and shielding rate in such a light-controlling devices.

"Research has been conducted on a light-controlling device that may be applied to windows, automobiles, airplanes, optical devices, or image display devices to control light transmittance or reflectance. The light-controlling device may block, reflect, scatter, or transmit light in an ultraviolet (UV) region, a visible light region, or a near-infrared (NIR) region due to the characteristics and movements of various kinds of charged elements.

"When the light-controlling device is applied to, or otherwise used as, windows of buildings or automobiles, the light-controlling device can control the transparency of the window to adjust the amount of light entering through the window. For example, the light-controlling device can be used to adjust the sunlight entering through the window to control the indoor temperature and brightness, and provide energy efficient environment.

"For most applications, both light transmittance rate and light shielding rate are important aspects of the light-controlling device. These properties, however, generally have a trade-off relationship with each other, and therefore it is often difficult to achieve both the high light transmittance and the high shielding rates at the same time. Attempts have been made by using polymer disperse liquid crystal (PDLC) having a varied light intensity, but it still lacks sufficient light transmittance and/or light shielding properties in many applications.

"Accordingly, there is still a need for a light-controlling device capable of providing both high transmittance and a high shielding rate."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "Accordingly, an aspect of the present disclosure relates to an improved light-controlling device. The light-controlling device includes a first substrate, a second substrate and a partition wall separating the first and second substrates to define a cell. In between the first substrate and the second substrate, a light-adjustment medium is disposed. The light-adjustment medium contains a plurality of charged particles, which may any one of a plurality of light-absorbing particles, a plurality of light-reflecting particles and a plurality of light-scattering particles. Further included in the light-controlling device are a first electrode and a second electrode. The first electrode is disposed on the first substrate to cover at least some part of the first substrate within the cell. The second electrode is disposed on the second substrate to cover at least some part of the second substrate within the cell. The first and second electrodes have different size. By way of an example, the first electrode may smaller size (i.e., length and width) than the second electrode such that the area of the first substrate covered by the first electrode within the cell is smaller than the area of the second substrate covered by the second substrate within the cell. In an embodiment, the first electrode within the cell covers about 0.1% to 10% of the total area of the first substrate enclosed within the cell.

"In some embodiments, the first electrode has a grooved surface with a projection of a first height and a recess with a first depth. Also, the diameter of each of the charged particles may be less than the first height and less than the first depth of the grooved surface. The grooved surface increases the total surface area of the first electrode while maintaining the size of the area on the first substrate being covered by the first electrode. The increased surface area of the first electrode allows for gathering and holding an increased amount of charged particles in comparison to the first electrode having a flat surface. Accordingly, the total amount of charged particles (e.g., concentration of the charged particles in the light-adjustment medium) in the device can be increased to maximize the light shielding property during the shielding mode without negatively affecting the light transmittance of the device during the transmissive mode.

"In some embodiments, the light-controlling device includes one or more particle guidance members that are thicker (in vertical direction) and are configured to create a hollow space over the first electrode. Some portion or the entire portion of the first electrode exposed through the hollow space, serving as the surface defining the bottom of the hollow space. In cases where there is a single first electrode and a hollow space within each cell, the volume of the hollow space formed on the first electrode is substantially the same or greater than the total volume of the charged particles within the cell. In cases where multiple first electrodes with hollow spaces are disposed within each cell, the total volume of the multiple hollow spaces is substantially the same or greater than the total volume of the charged particles within the cell. Without this hollow space on the first electrode, the charged particles tend to be collected widely around the first electrode, thereby affecting (e.g., blocking, reflecting, scattering) the light passing through larger area of the device even during the transmissive mode. Lesser amount of the charged particles can be employed within the cell so that lesser area is affected the charged particles during the transmissive mode, but the reduced amount of the charged particles may reduce the effectiveness of the light-controlling device during the light shielding mode. By forming the hollow space on the first electrode, however, the charged particles within the cell can be stacked on each other and be collected within the relatively narrow hollow space without having to use lesser amount of the charged particles within the cell. In other words, the amount of the charged particles within the cell can be maintained or even be increased without having to worry about the performance of the light-controlling device in both the light transmissive mode and the light shielding mode.

"In some embodiments, the hollow space is tapered such that its opening towards the second substrate is larger than the opening towards the first substrate. The larger opening towards the opposing substrate makes it easier for the charged particles to be drawn into the hollow space during when the first electrode is activated to pull the charged particles. For example, the hollow space may have sidewalls that extend at an angle of about 40.degree. to about 80.degree. toward the second substrate. In some embodiments, the particle guidance member has an angled surface that slopes towards the hollow space, which further aids the charged particles to move towards the hollow space when the first electrode is activated to pull the charged particles.

"The hollow space can be formed in a variety of ways by employing one or more of the particle guidance members. In some embodiments, a particle guidance member may have a hole, which extends through the particle guidance member towards the first electrode, thereby forming the hollow space over the first electrode to expose at least some portion of the first electrode. In some embodiments, multiple particle guidance members can be used. For example, a first particle guidance member can be disposed on one side (e.g., left) of the first electrode whereas a second particle guidance member can be disposed on other side (e.g., right) of the first electrode. Since the particle guidance members are thicker than the first electrode, the hollow space is formed on the first electrode positioned between the two particle guidance members. The side surfaces of the first and second particle guidance members and the upper surface of the first electrode defines the hollow space. The number of particle guidance members and their thickness can be adjusted depending on the desired shape and size of the hollow space. The ability of the particle guidance member to direct or otherwise guide the charged particles towards the first electrode and the size of the reservoir (e.g., hollow space) for holding the charged particles may vary depending on the application of the light-controlling device, the amount of the charged particles employed by the device as well as the amount of the charged particle to be held within the reservoir. For instance, the functionality of the particle guidance member and the reservoir can be adjusted by using the shape and dimension (e.g., angle, length, width, depth, etc.) of the particle guidance member, the tapered side wall, the first electrode, as well as the grooves of the first electrode.

"In an aspect, the present invention is directed to a light-controllable window. The light-controllable window includes a first transparent substrate having a collecting electrode, a second transparent substrate having a spreading electrode, and a light-adjustment medium containing a plurality of charged particles disposed between the first substrate and the second substrate. The collecting electrode and the spreading electrode are configurable to create electric field between the first and second substrates to cause movement of the charged particles dispersed in the light-adjustment medium. The light-controllable window further includes one or more particle guidance members that are arranged to form a hollow space that encloses the collecting electrode with an opening towards the light-adjustment medium.

"In yet another aspect, a method for manufacturing the light-controlling device is disclosed. In an exemplary method, a first electrode is formed on the first substrate and a second electrode is formed on the second substrate. The second electrode is larger than the first electrode so that, when the light-controlling device is viewed normally (i.e., perpendicular to the first substrate or the second substrate), relatively larger area is covered by the second electrode than the area of the light-controlling device covered by the first electrode. The method further includes forming at least one particle guidance member on the first substrate to form a hollow space that exposes at least some portion of the first electrode. Then, a light-controlling medium with a plurality of charged particles is sealed between the first and the second substrate.

"Aspects of the present invention should not be limited by the above description, and other unmentioned aspects will be clearly understood by one of ordinary skill in the art from exemplary embodiments described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

"The above and other objects, features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings, in which:

"FIG. 1 is a plan view of a light-controlling device according to an exemplary embodiment of the present invention;

"FIGS. 2 through 4 are cross-sectional views of the light-controlling device, which are taken along line II-II' of FIG. 1;

"FIG. 5 is a partial enlarged view of portion A in FIG. 4;

"FIGS. 6A and 6B are schematic views of an electric line of force for describing an electric field of a light-controlling device according to an exemplary embodiment of the present invention;

"FIGS. 7A and 7B are cross-sectional views of a light-controlling device according to various exemplary embodiments of the present invention;

"FIG. 8 is a graph showing a correlation between the thickness of a polymer layer and critical compression stress relative to the thickness of a metal layer, according to an exemplary embodiment of the present invention;

"FIGS. 9, 10, 11A, and 11B are cross-sectional views of light-controlling devices according to various exemplary embodiments of the present invention;

"FIG. 12 is a plan view of a light-controlling device according to another exemplary embodiment of the present invention;

"FIG. 13 is a cross-sectional view of a light-controlling device, which is taken along line XIII-XIII' of FIG. 12;

"FIG. 14 is a schematic view of an organic light-emitting diode (OLED) display device to which light-controlling devices according to various exemplary embodiments of the present invention may be applied; and

"FIGS. 15A, 15B, and 15C, and 16 through 18 are cross-sectional views illustrating processes of a method of manufacturing a light-controlling device according to an exemplary embodiment of the present invention."

For more information, see this patent application: SEONG, MiRyn; NOH, YoungHoon; LEE, MoonSun. Light-Controlling Device and Method of Manufacturing the Same. Filed December 9, 2013 and posted June 19, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4698&p=94&f=G&l=50&d=PG01&S1=20140612.PD.&OS=PD/20140612&RS=PD/20140612

Keywords for this news article include: Automobiles, Transportation, Lg Display Co. Ltd..

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Source: Politics & Government Week


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