Active solid-state devices (e.g. – transistors – solid-state diode – Responsive to non-electrical signal – Electromagnetic or particle radiation
Reexamination Certificate
1998-09-23
2002-04-02
Everhart, Caridad (Department: 2825)
Active solid-state devices (e.g., transistors, solid-state diode
Responsive to non-electrical signal
Electromagnetic or particle radiation
C438S030000, C438S057000, C257S010000
Reexamination Certificate
active
06365949
ABSTRACT:
The present invention relates to a substrate having a first surface and a second surface extending substantially in parallel to the first surface, the substrate being of a material of a first conductivity and provided with a plurality of electrically conducting channels which are extending exclusively in a direction perpendicular to the first and second surfaces, said channels having a second conductivity substantially larger than the first conductivity, the substrate being provided with at least one electrode on either one of the first and second surfaces, contacting at least one of said channels.
Such a device is known from WO-A-96/04585 which discloses an LCD having an active matrix of electronic components, like thin film transistors and thin film diodes, deposited on the outside surface of the LCD cell substrate.
It is to be observed that for the purpose of the present invention, the expression “exclusively in a direction perpendicular to . . . ” is intended to include deviations inherently due to the production process used. Moreover, the first and second conductivities differ at least by a factor of 1000, but preferably much more, e.g. more than a factor 10
5
.
U.S. Pat. No. 4,613,351 describes a glass material in which parallel conducting tracks are applied in a predetermined direction. The tracks are intended to deflect and detect electromagnetic radiation having a wavelength between less than 0.1 &mgr;m and 1 mm.
U.S. Pat. No. 5,438,223 describes a kind of rivet system for interfacial connection of an insulating layer with an electrically conducting material. The electrically conducting parts are applied in holes transversely through the layer and then thermally riveted.
Japanese Patent Application JP-A-081143677 describes the production of a sheet by depositing gaseous material on an electrode. The electrical conductivity in a direction perpendicular to the surface of the sheet is much greater than the electrical conductivity in a direction parallel to the surface of the sheet. However, the conductivity in the direction perpendicular to the surface is in the order of 10
−6
S/cm, which is very low and in the semiconductor range.
U.S. Pat. No. 5,272,217 describes the use of anisotropic polymers in a sheet. The conductivity parallel to the surface of the sheet of the polymer is much higher than the conductivity in a direction perpendicular to the surface of the sheet. The tetrathiotetracene complex is mentioned as one of the polymers used. Use is made of a “stack orientation” in which elements of very small dimensions are grouped head-to-tail.
U.S. Pat. No. 5,556,706 also describes particles of very small dimensions which are oriented head-to-tail in a direction parallel to the surface of a polymer sheet. The sheet is produced by depositing a gaseous material on an electrode. Here, again, there is a greater conduction in a direction parallel to the surface of the sheet than in a direction perpendicular thereto after production.
U.S. Pat. No. 5,229,635 describes a device and a method of orienting very small elements head-to-tail under the influence of an electrical field. Said patent specification is aimed at achieving an electrical conductivity in a predetermined direction parallel to the surface of the sheet. Incident light can be converted into electrical power with the sheet.
Japanese Patent Application 08/007658 describes an adhesive film which is provided with small conducting particles. Prior to use, the film is non-conducting because the conducting particles are not in contact with one another. The film is used to make a connection between the terminal pins of an IC and a substrate. Because the terminal pins of the IC are pressed firmly in the direction of the substrate, electrically conducting connections are produced between the terminal pins of the IC and the conducting particles in the film. As a result of pressing the terminal pins firm enough against the substrate, a conducting connection is produced between the terminal pins and desired electrically conducting tracks on the substrate. At those points where there are no IC terminal pins, the film remains non-conducting. Similar adhesive films are disclosed in U.S. Pat. No. 5,213,715 and Japanese Patent Application 57/111366 and 05/011265.
FIG. 1
shows in a very diagrammatic way the structure of a conventional LCD. The centremost of the three layers shown, indicated by the reference numeral
3
, is the optical layer. This is surrounded on either side by two controlling layers
2
,
2
′. The controlling layers
2
,
2
′ must be situated as closely as possible to the optical layer
3
. In essence, there are two types of optical layers: liquid crystals, which orient themselves under the influence of an electrical field, and light-emitting layers, which emit light under the influence of an electrical current. Light-emitting layers dissipate power during operation, while liquid crystals dissipate energy solely for the purpose of orientation. Light-emitting materials are, for example, LEDs, laser diodes and electroluminescent materials.
Where polarized light is employed, polarization filters are in practice also needed. Said polarization filters and any other correction filters are not described in more detail here because they are not of importance for the present invention. However, where necessary they can in fact be used.
The optical layer
3
generally comprises three layers
4
,
6
,
4
′, as shown in FIG.
2
. In addition, supporting layers
1
,
1
′ are situated on the outside of the controlling layer
2
,
2
′. The centrally situated layer
6
comprises a liquid-crystal layer in which spacers
5
are situated at regular or irregular distances in order to keep the two insulating layers
4
,
4
′ at a predetermined distance from one another. The primary function of the layers
4
,
4
′ is to facilitate the orientation of the liquid crystals in the same direction. Furthermore, they are important in preventing the liquid crystals from being contaminated by migration of ions, such as tin and indium, out of the conductor patterns
2
,
2
′. Finally, the layers
4
,
4
′ provide an insulating function.
The controlling layers
2
,
2
′ comprise, for example, transparent material which contains a pattern of, for example, parallel, likewise transparent conductors. The parallel conductors in the controlling layer
2
are then situated, for example, perpendicular to the transparent, parallel conductors in the controlling layer
2
′. Using such patterns, electrical fields can be generated at desired positions transversely or at an angle to the liquid crystal
6
layer, as a result of which the crystals in the liquid crystal layer
6
orient themselves. At the points where this occurs, the liquid crystal layer
6
becomes impenetrable to incident light.
In the conventional structure of an LCD shown in
FIG. 2
, the controlling layers
2
,
2
′ are situated inside the supporting layers
1
,
1
′. Such LCDs can be transported only when the supporting layers have been applied. Without the supporting layers
1
,
1
′, the LCD structure would be too vulnerable. As a result, it is impossible to make changes and/or corrections in the controlling layers
2
,
2
′ after the manufacture of the LCD.
In addition, before the controlling layers
2
,
2
′ have been applied, it is impossible to carry out checks on the correct operation of the liquid crystal layer
6
.
Moreover the production yield of LCDs according to the known structure is low. A high percentage, sometimes more than 70%, does not meet the requirements and cannot be sold.
A standard method of orienting the material of the insulating layers
4
,
4
′ horizontally is the so-called “rubbing” or frictional treatment. However, because the controlling layers
2
,
2
′ in the conventional arrangement are applied next to the insulating layers
4
,
4
′, there is a high risk of damage to said controlling layer
2
,
2
′ during the rubbing. This aris
Brouwer Hendrik-Jan
Hadziioannou Georges
Ruiter Jacobus Christiaan Gerardus Maria
Terlouw Erik Maarten
Everhart Caridad
Young & Thompson
Zetfolie B.V.
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