Liquid crystal cells – elements and systems – Liquid crystal optical element – Liquid crystal diffraction element
Reexamination Certificate
2000-08-28
2003-12-30
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Liquid crystal optical element
Liquid crystal diffraction element
C359S566000, C349S187000
Reexamination Certificate
active
06671031
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for manufacturing a polarization diffraction film which is excellent in heat resistance and generates diffracted light with a polarizability.
2. Description of the Prior Art
Diffraction elements are general-purpose optical elements which have been widely used for the purpose of spectrally splitting light or dividing luminous flux in the fields of spectroscopic optics and the like.
The diffraction elements are classified into some types according to their shapes. In general, they are classified into an amplitude type diffraction element having light-transmitting parts and non-light-transmitting parts which are periodically arranged, and a phase type diffraction element having grooves periodically formed on a high-transmittance material.
Alternatively, they may sometimes be classified into a transmission type diffraction element and a reflection type diffraction element according to the direction in which diffracted light is generated.
With the conventional diffraction elements as described above, the diffracted light obtained when ambient light, i.e. unpolarized light is made incident on the elements is restricted to unpolarized light.
With a polarizing instrument such as an ellipsometer frequently used in the fields of spectroscopic optics, the diffracted light can not be polarized. For this reason, there is generally employed a method in which the natural light emitted from a light source is spectrally split through a diffraction element and further in order to utilize only a specific polarization component contained therein, the diffracted light is made to pass through a polarizer to be used.
With this method, there is a problem that the quantity of light is reduced by half because about 50% or more of the resulting diffracted light is absorbed by the polarizer. Due to this problem, it is also required to prepare a detector with a high sensitivity and a light source capable of producing a large quantity of light.
Further, since the diffraction elements are often used in the optical field and design field including optical elements and optoelectronic elements and in recent years even in the security field, the diffraction elements themselves are required to have a certain degree of thermal and mechanical resistance.
Under such circumstances, there has been a demand for the development of a diffraction element which is excellent in thermal and mechanical resistance for ensuring the applicability of the elements in various fields and the resulting diffracted light itself becomes specific polarized light such as circularly polarized light or linearly polarized light.
BRIEF SUMMARY OF THE INVENTION
The present invention has been achieved in view of the foregoing problems. It is therefore an object of the present invention to provide a method for manufacturing a polarization diffraction film which is excellent in heat resistance and produces diffracted light having a polarizability.
The present inventors have found that a polarization diffraction film having an excellent heat resistance performance and a novel optical performance, i.e. a polarization diffraction property can be manufactured by imparting a diffraction capability to a cholesteric liquid crystal film combining an optical performance and a heat resistance performance, formed from a liquid crystal material containing a crosslinkable substance and thereby completed the present invention.
Namely, the method according to the present invention comprises the steps of forming a film with a liquid crystal material containing a liquid crystalline polymer and a crosslinkable substance; fixing a cholesteric alignment formed with the liquid crystal material; crosslinking the material to form a liquid crystal film; and providing a region exhibiting a diffraction capability on at least a part of the film thus obtained.
Another method for manufacturing a polarization diffraction film according to the present invention comprises the steps of forming a film with a liquid crystal material containing a liquid crystalline polymer and a crosslinkable substance; crosslinking the material which is in a cholesterically aligned state to form a liquid crystal film with a cholesteric alignment fixed: and providing a region exhibiting a diffraction capability on at least a part of the film thus obtained.
DETAILED DESCRIPTION OF THE INVENTION
Below, the present invention will be described in details.
The liquid crystal material to be used in the present invention contains a liquid crystalline polymer and a crosslinkable substance.
No particular limitation is imposed on the liquid crystalline polymer as long as it is a main chain type and/or side chain type liquid crystalline polymer compound or a liquid crystalline oligomer, all exhibiting a nematic liquid crystal phase or a cholesteric liquid crystal phase, or a composition containing a copolymer or mixture thereof.
Eligible main chain type liquid crystalline polymers exhibiting a nematic liquid crystal phase are polyamide, polyamic acid, polyimde, polyester, polyether, polysulfide and cellulose derivatives.
Among these liquid crystalline polymers, the liquid crystalline polyester is preferred from the following viewpoint.
That is, the polyester is generally comprised of an aromatic or aliphatic diol unit, an aromatic or aliphatic dicarboxylic acid unit or an aromatic or aliphatic hydroxycarboxylic acid unit. The polymeric terminal ends of the polymer are often a hydroxycarbonyl group (carboxyl group) or a hydroxy group, i.e., the reactive group of the unit monomer.
These terminal functional groups participate as a crosslinking ends in the reaction with the crosslinkable substances described below, or catalytically act on the reaction of the crosslinkable substance itself so as to facilitate the crosslinking. Further, the liquid crystalline polyester has an excellent alignment and is relatively easy to synthesize. For these reasons, the liquid crystalline polyester can be exemplified as a desirable liquid crystalline polmer in the present invention.
The liquid crystalline polyester employable for the present invention is desirably in the range of generally 10 to 1,000 &mgr;mol/g, preferably 30 to 500 &mgr;mol/g, and more preferably 50 to 300 &mgr;mol/g in terms of terminal carboxylic acid equivalent weight per polymer weight.
The main chain type liquid crystalline polymer employable for the present invention can be obtained with ease by a known condensation polymerization method and an acid chloride method but is not restricted by these synthesis method.
Specific examples of the side chain type liquid crystalline polymer exhibiting a nematic liquid crystal phase include those each having such a structure that polysiloxane, polyacrylate, polymethacrylate or polymalonate is a main chain and a low molecular weight liquid crystal compound comprised of a para-substituted cyclic compound as a mesogen is bonded, if required, via a spacer comprised of conjugated atomic groups to the main chain.
Preferred para-substituted cyclic compounds are those capable of exhibiting a nematic liquid crystal phase. Specific examples of such compounds are those having the para-substituted aromatic units of azometine, azo, azoxy, ester, substituted or non-substituted phenylene, substituted or non-substituted biphenyl, terphenyl, phenylcyclohexane, substituted or non-substituted naphthalene and anthracene types and substituted cyclohexane ring units of 1,4-substituted cyclohexane and bicyclohexane types.
In the present invention, the compounds having the para-substituted aromatic units of the phenylene, biphenyl and naphthalene types are particularly preferred form the viewpoints of the nematic liquid crystallinity and the availability of the materials.
Examples of the terminal substituent at the para position, i.e., at the site of the carbon more distant from the carbon bonded to the main chain or spacer or at the site of the carbon most distant from the main chain when a plurality of cyclic compounds are used, in the para-substitu
Nippon Mitsubishi Oil Corporation
Parker Kenneth
LandOfFree
Method for manufacturing polarization diffraction film does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for manufacturing polarization diffraction film, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for manufacturing polarization diffraction film will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3156921