Patent Description:
PDLC as screens for projected images have been around a long time due to exceptional image quality of PDLC due to birefringent LC micro-droplets, most producers of commercial PDLC film are also selling it for integrated use of privacy-projection applications. The quality of these systems depends on several aspects, some of them are: the quality of the projector, the quality of the PDLC, the morphology of the PDLC, the ambient lighting conditions and others.

Some of the most prevalent reasons that caused the slow penetration of PDLC as screen projection devices are the high cost of production of PDLC in relation with the performance of the same as projection screen devices. Also, mainly due to price and its commercial availability of the Active (switchable) mode. More than <NUM>% of potential PDLC film for RPS market is for Passive mode.

Some examples of prior art in this field are:.

Even in today's advancements in technology, the relation between PDLC physical/optical properties and image quality are poor understood, mainly because of lack of R&D strategy, resources and business interest in a market different than privacy glass, all PDLC film producers are promoting the projection application as a secondary application of their privacy film.

The aforementioned prior art have something in common. They all try to meliorate the quality of the screened image on the PDLC screen. They try to use very complex and cumbersome solutions in order to enhance the perceived quality of the image on the PDLC screen. But none is concentrating their efforts to upgrade the quality of the PDLC.

Therefore, there is a long felt need to provide a high quality image, simple, low cost and technological PDLC as means to screen any kind of image at any lighting condition. Between these, Passive PDLC screens for majority RPS and FPS markets, as well as active PDLC for high-end niche markets.

The primary object of this invention, as described in detail below and defined in the claims, is to disclose a novel method of manufacturing a PDLC projection screen. Various embodiments of a PDLC projection screen that is a product of the inventive method are described herein, however, as background art presented to assist a person of ordinary skill in the art in understanding how to make and use the invention disclosed herein, Similarly, embodiments of a projection screen that contains liquid crystals but that is not necessarily PDLC-based are disclosed as examples of background art useful to an understanding of how to make and use the invention disclosed herein.

It is hence an object of the invention to disclose a method for manufacturing a PDLC projection screen, according to claim <NUM>, comprising the steps of: providing materials for producing a PDLC film, said materials comprising: at least two transparent metalized polymer supports; and at least one liquid crystal dispersion; allocating said liquid crystal dispersion between said at least two transparent polymer supports, thereby forming a PDLC film; curing said PDLC film by means of UV light, electron beam light or heat; controlling quality parameters of said PDLC projection screen; wherein said step of controlling said PDLC projection screen comprises verifying that said quality parameters are equal to: a total light transmittance Tt of about <NUM> to about <NUM>%, a diffuse transmittance Dt of about <NUM> to about <NUM>%, a clarity C of <NUM> to <NUM>% and a haze value H of about <NUM> to about <NUM>%, measured in accordance with either ASTM D1003 - <NUM>, ISO <NUM>-<NUM>:<NUM> or ISO <NUM>-<NUM>:<NUM>.

A further object of the invention is to disclose the method wherein said at least two transparent polymer supports are metalized coated and used for active screening methods.

A further object of the invention is to disclose the method wherein said at least two transparent polymer supports are non-metalized coated and used for passive screening methods.

A further object of the invention is to disclose the method further comprising retrofitting said PDLC film into an already existing surface.

It is hence another object of the invention to disclose a method for manufacturing a multilayer of liquid crystal dispersion in a polymer matrix film adapted for a PDLC projection screen, according to claim <NUM>, comprising the steps of: providing materials for producing a PDLC film, comprising: at least one first releasable supporting film; at least one liquid crystal dispersion; at least one second supporting film; allocating said liquid crystal dispersion between said at least one first releasable supporting film and said at least one second supporting film, thereby forming a PDLC film; curing said PDLC film by means of UV light, electron beam light or heat; detaching said at least one releasable supporting film; providing materials for producing at least one second layer of liquid crystal in said PDLC film, comprising: a third supporting film; a second liquid crystal dispersion; allocating said second liquid crystal dispersion between said third supporting film and said PDLC film, thereby forming a multilayer PDLC film; curing said multilayer PDLC film by means of UV or electron beam light; and controlling the quality parameters of said PDLC projection screen; wherein any of said supporting films can be releasable supporting films; further wherein said step of controlling said PDLC projection screen further comprises a step of verifying that said quality parameters comprise: a total light transmittance Tt of about <NUM> to about <NUM>%, a diffuse transmittance Dt of about <NUM> to about <NUM>%, a clarity C of <NUM> to <NUM>% and a haze value H of about <NUM> to about <NUM>%, measured in accordance with either ASTM D1003 - <NUM>, ISO <NUM>-<NUM>:<NUM> or ISO <NUM>-<NUM>:<NUM>.

The following description is provided, to enable any person skilled in the art to make use of the invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, are adapted to remain apparent to those skilled in the art, since the generic principles of the present invention have been defined specifically to provide a PDLC adapted to provide a high quality of image in a projection screen system. Thus, a novel method for creating such films has been obtained.

The term "haze (H)" refers hereinafter to see-through quality, and total transmittance of a material, based on how much visible light is diffused or s scattered when passing through a material. Also, the percentage of light that when passing through deviates from the incident beam greater than <NUM> degrees on average.

The term "total transmittance (Tt)" refers hereinafter to the measure of the total incident light compared to the light that is actually transmitted (e.g. total transmittance). So the incident light may be <NUM>%, but because of absorption and reflection the total transmittance may only be <NUM>%. Total Transmittance can be divided into (a) Direct Transmittance and (b) Diffuse Transmittance.

The term "direct transmittance" refers hereinafter to the portion of the light that passes through the film without being scattered or diffused by the irregularities on the surface or the interior of the film. Also referred to as the percentage of light that when passing through deviates from the incident beam up to <NUM> degrees on average.

The term "diffuse transmittance (Dt)" refers hereinafter to the portion of light that is scattered or diffused by these irregularities.

Diffuse Transmittance is a combination of haze and clarity, both measures of the degree of scatter.

The term "clarity (C)" refers hereinafter to the measure of narrow-angle scattering, and causes the detail of an object to be compromised when viewing it though the film. Clarity is also distance-dependent, which means that the farther the object is being viewed through the film, the worse its detail becomes.

The term Retrofit(ting) refers hereinafter to the modification of a conventional window or surface by combining the same in some manner with an enhancement, i.e., a switchable glazing, non-switchable light modulating device, etc..

The present invention is prompted by shortcomings in the application of current PDLC film technology and lack of proper penetration of exiting PDLC products in the projection screen market is based on improvement of PDLC technology and developing new passive and active high-image quality and large-area rear and front projection screens.

The present invention is based on adaptation of PDLC film technology and development of a series of novel and high-quality non-switchable and switchable rear and front projection screens with improved image qualities for various lighting conditions.

One aspect of the present disclosure is to establish and quantify the structure-property relations between physical and optical properties of PDLC screen with the quality of the projected image, leading to quantitative a modeling of the device.

An embodiment of the invention is to manufacture large-area passive and active high-quality projection screens for information, multimedia and entertainment markets.

In a preferred embodiment of the present invention, a release sheet is used in the manufacturing of the PDLC screen projection. A release sheet enables the manufacturing of a PDLC and at the end of said manufacturing the sheet is removed from the PDLC without problem and without damaging the physical characteristics of said PDLC. The release sheet can be made from a variety of materials, like Polyethylene (PE) of any kind, Polypropylene (PP) of any kind, non-coated thin (e.g. <NUM>-50Micron) PET, and any kind of non-shrinkable plastic like Ethylene Vinyl Acetate (EVA) films. In certain embodiments, the release sheet is coated with polymers that facilitates the removal from the liquid crystal. In other embodiments, the release sheet is positively or negatively charged in order to facilitate the removal of the sheet. It will be obvious for a person skilled in the art that variations in the polymers, materials or coatings can be used for the manufacture of releasable sheets.

In one embodiment of the present invention, the PDLC screen projection can be passive or active.

In another embodiment of the present invention the passive or active PDLC screen projection is manufactured in a two-step fabrication phases.

In Phase I of the manufacturing process, a pre-form PDLC is created in order to allow flexibility when moving to Phase II of the process. The idea is to create the materials needed for Phase II, while conserving certain flexibility in the usage of the same. From different Phase I pre-form materials - different final products of Phase II can be produced.

The materials used in the Phase I can be PET, PET-ITO, PET with any other conductive or metalized coating (e.g. PET-silver), liquid crystal suspension (LC) and release films. It will be obvious to a person skilled in the art, that variations of those are also included in the scope of the present invention.

The materials used in the Phase II can be glass, polycarbonate, Plexiglas and others. All of them can be metalized coated or not.

In another embodiment of the present invention, the passive PDLC screen projection can have the following configurations depending on the respective step of the fabrication phase:.

It is important to mention that in the case of passive PDLC screen projection, one of either the glass or the PET can have a metalized coating in order to enhance the quality of the image that is being screened.

The passive PDLC screen projection possible configurations can be summarized by the following table:.

The methods of fabricating the PDLC Phase I with the configuration PET-LC-PET are known in the art.

In another embodiment of the present invention, the active PDLC screen projection can have the following configurations depending on the respective step of the fabrication phase:.

The active PDLC screen projection possible configurations can be summarized by the following table:.

The methods of fabricating the PDLC Phase I with the configuration PET-ITO-LC-PET-ITO are known in the art.

Referring now to <FIG>, showing one method of manufacturing the PDLC for screen projection. The method is similar to that of a regular PDLC. <FIG> upper side shows how the liquid crystal <NUM> is poured <NUM> between two supporting films, one can be PET (for passive) / PET-ITO (for active) <NUM> while the second one is a "releasing sheet" <NUM>. The film passes then in the UV oven <NUM> and then dried in chamber <NUM>. Rotors <NUM> and <NUM> confer the final thickness to the film, which is later rolled <NUM>. <FIG> lower side shows the final film which comprises a layer of PET (for passive) / PET-ITO (for active) <NUM>, a layer of liquid crystal <NUM> and the "release sheet" <NUM>, which is then peeled away and can be replaced by a regular glass (for passive) or metalized coated glass (for active) <NUM>.

Referring now to <FIG>, showing another method of manufacturing the PDLC for screen projection. The method is similar to that of a regular PDLC. <FIG> upper side shows how the liquid crystal <NUM> is poured <NUM> on one supporting film, it can be PET (for passive) / PET-ITO (for active) <NUM>. The film passes then in the UV oven <NUM> and then dried in chamber <NUM>. Then the second support film is attached to the film. This film is a "releasing sheet" <NUM>. Rotors <NUM> and <NUM> confer the final thickness to the film, which is later rolled <NUM>. <FIG> lower side shows the final film which comprises a layer of PET (for passive) / PET-ITO (for active) <NUM>, a layer of liquid crystal <NUM> and the "release sheet" <NUM>, which is then peeled away and can be replaced by a regular glass (for passive) or metalized coated glass (for active) <NUM>.

Referring now to <FIG>, showing yet another method of manufacturing the PDLC for screen projection. The method is similar to that of a regular PDLC. <FIG> upper side shows how the liquid crystal <NUM> is poured <NUM> between two supporting films, both are "releasing sheet" films <NUM>. The film passes then in the UV oven <NUM> and then dried in chamber <NUM>. Rotors <NUM> and <NUM> confer the final thickness to the film, which is later rolled <NUM>. <FIG> lower side shows the final film which comprises a layer of liquid crystal <NUM> and two "release sheets" <NUM>, which are then peeled away and can be replaced by two regular glasses (for passive) or two metalized coated glass (for active) <NUM>.

Referring now to <FIG>, showing yet another method of manufacturing the PDLC for screen projection. The method is similar to that of a regular PDLC. <FIG> upper side shows how the liquid crystal <NUM> is poured <NUM> on one supporting film, which is a "releasing sheet" <NUM>. The film passes then in the UV oven <NUM> and then dried in chamber <NUM>. Then the second support film is attached to the film. This film is also a "releasing sheet" <NUM> film. Rotors <NUM> and <NUM> confer the final thickness to the film, which is later rolled <NUM>. <FIG> lower side shows the final film which comprises a layer of liquid crystal <NUM> and two "release sheets" <NUM>, which is then peeled away and can be replaced by two regular glasses (for passive) or two metalized coated glasses (for active) <NUM>.

Referring now to <FIG>, showing either one of the resulting films of <FIG>, which comprises a layer of liquid crystal <NUM> and two "releasing sheets" <NUM>. Once the "releasing sheets" are peeled away, the remaining layer of liquid crystal <NUM> can be further treated with stretching and liquid crystal domain orientation.

The present invention is based on adaptation of PDLC film technology and development of a series of novel and high quality switchable and non-switchable single- and multi-layer screens for large-area rear and front projection screen applications.

Methods of how to fabricate single layer passive and active PDLC projection screens were mentioned above.

Methods of how to fabricate multi-layer passive and active PDLC projection screens are described herein:.

All the PDLC projection screens, whether they are active or passive can be manufactured as rigid screens of flexible screens.

The main difference between the two is the final step of Phase II, where in the case of a rigid screen there is a step of lamination of the cured PDLC layer onto a rigid (glass, polycarbonate, Plexiglas, etc.) non-metalized (for passive)/ metalized (for active) support. In contrast, in the case of a flexible screen there is a step of In-situ coating and laminating and complete processing of highly-adhesive PDLC layer (<NUM>-<NUM>) between two non-metalized (for passive) / metalized (for active) film supports.

In a preferred embodiment, the multilayer PDLC, LCDP, PSLC, polymer network film or PDLC projection screen can be enclosed between two glasses or may be retrofitted on existing interior and exterior architectural glazing, automotive windows, and other interior glazing. A transparent adhesive may be used to stick the panel to the window, which may be integrated with the panel or separately provided. The panel may also be applied to original windows before installation.

PDLC projection screens were manufactured as mentioned above. Performance of said screens was measured in accordance with either ASTM D1003 - <NUM>, ISO <NUM>-<NUM>:<NUM> or ISO <NUM>-<NUM>:<NUM>. The results of said measurements are as follows:.

Therefore, it is a scope of the present invention to provide passive or active PDLC projection screen, in either rigid or flexible form, having a total light transmittance Tt of about <NUM> to <NUM>%, a diffuse transmittance Dt of about <NUM> to <NUM>%, a clarity C of <NUM> to <NUM>% and a haze value H of about <NUM> to <NUM>%, measured in accordance with either ASTM D1003 - <NUM>, ISO <NUM>-<NUM>:<NUM> or ISO <NUM>-<NUM>:<NUM>.

The PDLC can be activated or deactivated in order to "allow" the images screened on it to be seen or not. This example works great on stores showcases. The projection screen, couples to a motion sensor, can show the image that is screened, and once potential clientele approaches and the sensors are activated, the projection screen becomes transparent allowing the person or persons to look inside the showcase.

Opposite to example <NUM>, the coupling of a motion sensor to the PDLC projection screen can be used for energy saving. The projection screen is transparent and not in use. Once the sensor is activated by a person walking by, the projection screen is activated, becomes opaque and the screened images will be seen.

Using the same principle, the PDLC projection screen can be activated or deactivated when needed or not. When is not needed, the PDLC projection screen can be transparent, and when it is needed, the PDLC projection screen becomes opaque and the projection can begin.

Transparency (or opacity) of the PDLC projection screen can be automatically controlled using the specialized dimmer created by Gauzy. The dimmer is a power dimmer apparatus operative to provide AC current to said PDLC projection screen to generate a set of transparency states between opaque and full transparent. Therefore, the dimmer allows the complete control of the activation level of the PDLC projection screen. From completely opaque, to a variety of transparency states, to a completely transparent PDLC projection screen. This opens a wide spectrum of applications for the PDLC projection screen of the present invention. Applications that can only be possible using the specifics of the present invention.

Said PDLC projection screen can be further connected to at least one sensor selected from group consisting of: movement sensor, temperature sensor, location sensor, humidity sensor, light sensor, and any combination thereof.

Claim 1:
A method for manufacturing a PDLC projection screen, comprising the steps of:
providing materials for producing a PDLC film, said materials comprising:
at least two transparent polymer supports (<NUM>, <NUM>); and
at least one liquid crystal dispersion (<NUM>);
allocating said liquid crystal dispersion between said at least two transparent polymer supports, thereby forming a PDLC film;
curing said PDLC film by means of UV light, electron beam light or heat; and
controlling quality parameters of said PDLC projection screen;
wherein said step of controlling the quality parameters of said PDLC projection screen comprises verifying that said quality parameters comprise: a total light transmittance Tt of about <NUM> to about <NUM>%, a diffuse transmittance Dt of about <NUM> to about <NUM>%, a clarity C of <NUM> to <NUM>% and a haze value H of about <NUM> to about <NUM>%, measured in accordance with either ASTM D1003 - <NUM>, ISO <NUM>-<NUM>:<NUM> or ISO <NUM>-<NUM>:<NUM>.