WO1999018320A1

WO1999018320A1 - Liquid crystal window shade

Info

Publication number: WO1999018320A1
Application number: PCT/US1998/020986
Authority: WO
Inventors: John L. Janning; Sharon Elliott
Original assignee: Aristech Acrylics Llc
Priority date: 1997-10-07
Filing date: 1998-10-06
Publication date: 1999-04-15

Abstract

The present invention comprises a window material comprising two liquid crystal material cells or panels opposite each other. The opaque appearing liquid crystal material is sectioned into a plurality of segments on at least one of the cells. A voltage source can be applied to one or more of these segments, across the cells, to produce a transparent appearance in the selected segments. The effect is to create a window shade appearance in the window material.

Description

LIQUID CRYSTAL WINDOW SHADE

RELATED APPLICATION

This application claims priority from Provisional Application No. 60/061 ,303 filed October 7, 1997.

TECHNICAL FIELD

This invention relates to the use of a liquid crystal material to selectively control light transmission through a transparent or semitransparent panel, and more particularly to the use of a liquid crystal material to provide a window shade of adjustable area transmittance. The window shade is made to appear as a normal up-down window shade or a Venetian blind type window shade. Fabrication is similar to the well known polymer dispersed liquid crystal (PDLC) displays.

BACKGROUND OF THE INVENTION

The present invention uses liquid crystal materials to provide an adjustable area to control light transmission in windows. Generally, the use of a liquid crystal material to selectively control light transmission through a transparent panel or window is known. However, this selective control has always been accomplished by altering the optical density of the liquid crystal window panel over its entirety. Representative patents disclosing the nature of liquid crystal materials and their uses can be found in U.S. Patent No. 4,005,928 to Kmetz; U.S. Patents Nos. 4,268,126 and 4,456,335 to Mumford; U.S. Patents Nos. 4,848,875 and 5,111 ,629 to Baughman, et al and 5,200,107 to Piermattie and Elliott.

Other electrical and mechanical shading techniques previously used for windows are as follows: (1 ) Shutter systems in which mechanical shutters are selectively operable to control shading; (2) Photochromic systems in which a photochromic material responds to changes in incident light so as to ncreasingly darken in response to higher intensities of light and to become less dark in response to lower intensities of light; (3) Tinted systems in which tinting is controlled by tinted liquid pumped between glass panes; and (4) Polarizer systems containing light polarizers.

SUMMARY OF THE INVENTION

The present invention provides an electro-optical liquid crystal window shade of adjustable area light transmittance. For example, the cell preferably contains a poymer mixed with the liquid crystals to form what is generally known as a PDLC (polymer dispersed liquid crystal) cell. However, the present invention is not limited to this specific embodiment of liquid crystal material.

A typical PDLC cell or panel is made by sandwiching nematic liquid crystals mixed with a polymer between two transparent substrates having a transparent electrical coating, such as ITO (indium-tin-oxide) on the inner surfaces. The two plates are spaced close to each other with a spacing of less one-thousandths of an inch or less. Such displays are well known in the art.

The present invention also provides an electronic means of operating a window shade from the bottom up, from the top down, from side to side, etc. Conventional mechanical window shades as used in most homes provides a means of shading from the top down. When such a shade adjacent a window is all of the way up, light and objects can be seen clearly through the window. When the shade is all of the way down, some diffused light is transmitted through the shade but no objects can be seen or discerned. Most of the time, such conventional shades are in a half down mode.

In the present invention, the same or similar effect can be accomplished in an electronic manner. Instead of having an infinite number of shade states as can be had in a mechanical shade such as the well known Venetian blind, a large finite number of segments can be addressed in the electronic window shade. An added benefit can be had in the electronic window shade in that the opaque portion can be adjusted electrically to be of any opacity from its opaque state to its clear state. In such a manner, the shaded portion can be adjusted to see objects in sort of filtered state.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the segmented shade in the Off or closed position.

Figure 2 shows the segmented shade in the 'on' or open position.

Figure 3 shows the segmented shade in the partially open position.

Figure 4 shows the segmented shade in a 'louvered' open/closed position.

Figure 5 shows the segmented shade in a 'louvered' closed/open position.

Figure 6 shows the segmented shade in a 'peep-hole' position.

DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 2 illustrate the liquid crystal window shade 10 in the closed (Off) and the open ('on') positions respectfully. In Figure 1 , no voltage from power supply 11 through switch 20 is applied to any of the polymer dispersed liquid crystal (PDLC) segments 12 that make up the liquid crystal shade, therefore, the shade is in the 'off or closed position.

The slider 14 is a sliding electrical switching contact means used for connecting the electrical supply from power supply 11 to the segments 12 through segment electrode line conductor strips 16. Electrical conductors 16 may be in the form of an etched copper strip pattern delineated on a printed circuit board. Likewise, slider bar 14 is an electrical conductor and may slide over conductive contact pad 13 and over some or all of the segment electrode line conductor strips 16 to provide electrical connection to the selected segments 12.

Conductive contact pad 13 can be in the form of a copper area delineated on the same printed circuit board along with segment electrode line conductor strips 16. The slider 14 is the only moving part and its function is to connect conductive contact pad 13 to the selected segment electrode line conductor strips 16.

In Figure 1 , the slider bar 14 is entirely positioned over contact pad 13 and does not come into contact with any of the segment electrode line conductor strips 16, therefore, the window shade 10 is in the 'off or closed position.

In Figure 2, slider 14 is fully extended over all of the segment electrode line conductor strips 16, thus, providing electrical connection from the power supply 11 to the segmented PDLC elements 12. The common electrode 17 contacts the backside contact of the PDLC display segments and is not switched.

Figure 3 shows the shade in an approximate half open position as found in many households with vinyl window shades, Venetian blinds or the like. The top portion of the shade is 'off (closed) but diffused light can still enter. Note that the slider 14 is partially extended connecting only those segment electrode line conductor strips 16 that are needed for the specific type of operation desired. The slider switch assembly 20 is constructed so the slider 14 can move laterally as well as up and down. This is shown in Figure 4 where every third segment 12 can be left 'off or closed. As the slider 14 is moved sideways, it can be seen that less and less segments 12 are connectable. Moving the slider 14 one more position, as shown in Figure 5, every third segment 12 can be in the 'on' or open position. The slider switch assembly 20 can be constructed to provide multiple patterns of 'off and 'on' conditions. A novel condition is shown in Figure 6 where a tiny peep-hole is provided by connecting only one segment 12 about midway in the shade so that one can look out, similar to conventional peep-holes in doors. Note that the large bar type electrode 15 can be connected to a single electrode line from segment electrode line conductor strips 16.

The invention is illustrated by, but not limited to the following example.

Example

An experimental window was fabricated by etching fine line openings in an indium-tin oxide (ITO) electrically conductive film deposited onto a glass plate. These openings were used to segment one of the two ITO coated plates making up the window. Standard photolithographic techniques were used for this delineation. Figure 2 depicts such segments. These fine line openings are preferably on the order of one-thousandths of an inch (0.001"). The segment dimensions are selected on the basis of functional and decorative desirability. The opposing plate remains continuously ITO coated.

The window is constructed by sandwiching liquid crystal material between the two plates with the electrically conductive ITO films facing each other and having tiny plastic or glass spacers therebetween to prevent the two plates from touching and shorting. These tiny spacers are on the order of ten microns or 0.0004".

The liquid crystal material makeup could consist of any number of recipes. One that was used successfully was approximately 92% E-7 liquid crystal material supplied by Merck with approximately 8% SK-9 optical cement supplied by Summers Optical. A trace of cholesteryl pelargonate was added to this mixture along with a fractional percent of spacers. All percentages were by weight.

After the window plates were sandwiched together with the liquid crystal material, spacers, etc., it was exposed to ultraviolet (UV) light for curing the UV sensitive SK-9 cement. This curing depends upon time, distance from light source and intensity of the UV source. Using two 20 watt UV fluorescent lamps at a distance of 18", a time of 30 minutes is adequate for curing the polymer.

The window was operated by applying the standard 120 volt 60 Hertz power as supplied in homes as the power supply. The power supply can also be of another voltage and frequency. Applying the full 120 volts AC to the segments caused them to change from a milky opaque appearance to a clear transparent state. Moving the slider bar 14 added more clear segments.

Claims

1. A window material comprising a liquid crystal dispersed material having a first and second surface wherein each of the surfaces is contacted by an electrically conductive material, and wherein the electrically conductive material on the first surfaces comprises at least two sections, and wherein a voltage can be applied between the electrically conductive material on each of the first and second surfaces, and wherein the voltage can be applied independently to each section of the electrically conductive material on the first surface, and wherein two or more sections of a transparent electrically conductive material on the first surface are positioned adjacent to the second surface having at least one section of transparent electrically conductive material with liquid crystal material between the two surfaces of said window material.

2. A window material according to claim 1 wherein the electrically conductive material is indium-tin oxide.

3. A window material according to claim 1 wherein the electrically conductive material is a thin deposited gold film.

4. A window material according to claim 1 wherein the electrically conductive material is contacted to a polyester film.

5. A window material according to claim 1 wherein the electrically conductive material on the second surface comprises at least one section that is addressed by at least one section from the first surface.

6. A window material according to claim 1 wherein each of the sections on the first surface are separated from each other by about 3/1000 of an inch or less.

7. A window material according to claim 1 wherein each of the sections on the second surface are separated from each other by about 3/1000 of an inch or less.

8. A window material according to claim 1 wherein the sections on the first surface are in the shape of rectangular strips having a width between 1/8 to 4 inches.

9. A window material according to claim 1 wherein the sections on the second surface have a width greater than 1/8 inches.

10. A window material according to claim 1 wherein the liquid crystal material is a polymer dispersed liquid crystal material.

11. A window material comprising a plurality of liquid crystal display cells, said cells defining a plurality of sections, said sections being in close proximity to one another so as to appear as one continuous optically clear area, and wherein said cells can be selectively energized to provide activation of at least one of said sections, and wherein any number of said sections becomes optically transparent by applying a voltage power source to said sections.

12. A window material according to claim 11 wherein the power source is alternating current having a frequency between 50 and 5000 Hertz. A window material according to claim 11 wherein the power source is the standard 120 volt 60 Hertz supply.