Compositions: coating or plastic – Coating or plastic compositions – Alkali metal silicate containing
Patent
1980-11-10
1983-12-13
Punter, William H.
Compositions: coating or plastic
Coating or plastic compositions
Alkali metal silicate containing
10628734, 106291, 350320, 427162, 427167, G02F 1133, G02B 110, B05D 506, C08K 706
Patent
active
044202245
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a liquid crystal display cell, hereinafter abbreviated as an LC-cell, which has two cell plates coated with electrodes including a liquid crystal mass; at least the first cell plate is transparent and the second cell plate is equipped, at least in some parts, with an adhesive cell interior reflector layer which contains flake-like aluminum particles as reflector particles and a bond for these. The invention concerns also a process for the production of such LC-cells as well as a plate for use in such cells.
DESCRIPTION OF THE PRIOR ART
Certain types of LC-cells (also known as LC-displays or LCD's) require a layer at least in part reflecting the light falling upon it, for example a more or less reflective layer, which is positioned above the electrode coating on the interior side of the cell as a so-called interior reflector and, for example, is applied by means of vaporization.
In order to exclude certain disadvantages of the common, that is vaporized interior reflectors of LC-cells with regard to operating and production costs, it is already known, for example from the DE-OS 26 39 675 and 27 16 609 of the applicant, that the interior reflector layer should be formed essentially of a variety of metal plates or flakes, especially of an aluminum pigment or "aluminum bronze", i.e., flake-like aluminum particles.
For this a paste-like mixture, which contains the aluminum particles and a temporary bonding agent, can be applied on the surface to be structured with the interior reflector of the corresponding cell plate, for example by means of screen printing. According to the afore-mentioned DE-OS 26 39 675, glass soldering powder can be added to the mixture which acts as a continuous bonding agent, i.e., as a bonding phase, after being burned in. According to the afore-mentioned DE-OS 27 16 609, however, it is possible to use only a temporary bonding agent in the mixture and to remove this practically without any residues after being burned in. The external aluminum oxide coating, which is formed almost spontaenously on the flake-like aluminum particles by means of atmospheric oxygen or produced specifically by a special treatment acts as a bonding phase and an electrical insulator in both cases which is supposed to prevent an electrical bridging of separated electrode areas of the LC-cell plates having an interior reflector.
The use of glass solder in the mixture used for the production of the interior reflector is problematic for a number of reasons and, in any event, does not provide optimal and sufficient thin interior reflector layers in the technical production stage of LC-cells which probably is a result of the relatively high strength of the glass solder in a melted state and/or of the insufficient homogeneity of the mixture.
The interior reflectors, formed practically only from metallic aluminum flakes and their oxide external layers, in accordance with DE-OS 27 16 609 can be shaped with sufficient thinness but have the disadvantage that the vertical orientation, which is either desirable or necessary for many types of LC-cells as can be achieved by the application of a silane layer on the interior surface of a cell plate, is practically not possible on the interior reflector because this has an uneven surface. Even the well-known mechanical friction of the interior surface of the cell plates, that causes a parallel orientation of the fluid crystal molecules and is required for some types of LC-cells, cannot be performed on the familiar interior reflector layers because these are not wipe-resistant or not sufficiently well-fixed enough on the cell plate.
Finally, an interior reflector layer consisting practically only of surface oxidized aluminum flakes has the disadvantage of insufficient mutual electrical insulation of the flakes in some instances, especially if the layer is burned in at temperatures between 400.degree. and 500.degree. C. and/or if the electrode regions or segments of the plates bearing the interior reflectors have separator zones of
REFERENCES:
patent: 2803566 (1957-08-01), Smith-Johannsen
patent: 2941894 (1960-06-01), McAdow
patent: 3932026 (1976-01-01), Sprokel
patent: 3988494 (1976-10-01), McAdow
patent: 4213676 (1980-07-01), Kaufmann
BBC Brown Boveri & Company Limited
Punter William H.
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