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Claims  |
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What is claimed is:
1. Device for displaying information, comprising at least:
a first layer which extends in one plane and is composed of a material whose optical properties vary under the influence of an external electrical control system in such a way that either the transparency of portions selected with the electrical
control system of the first layer for light incident thereon varies or portions selected with the electrical control system of the first layer emit light;
a second and a third layer which extend substantially parallel to the plane, are situated on either side of the first layer and impart to the device a certain desired rigidity, at least one of the second and third layers having a first
conductivity and being provided with at least one electrode and with electrically conducting channels which are extending exclusively in a direction perpendicular to the plane, said channels having a second conductivity substantially larger than the
first conductivity, said at least one electrode electrically contacting at least one of said channels,
wherein said at least one electrode has a minimum dimension (D) in a contact area with said at least one of the second and third layers, mutual distances between at least some adjacent ones of the plurality of channels being smaller than said
minimum dimension (D) of said at least one electrode, and wherein maximum mutual distances between all adjacent ones of the plurality of channels are smaller than said minimum distance (D) of said at least one electrode.
2. Device according to claim 1, characterized in that the first layer is a liquid-crystal layer provided with spacers and in that a fourth layer which is made of an electrically insulating material is situated between one of the second and third
layers mentioned and the first layer.
3. Device according to claim 1, characterized in that the first layer is a polymer dispersed liquid-crystal layer and in that a fourth layer which is made of an electrically insulating material is situated between one of the second and third
layers mentioned and the first layer.
4. Device according to claim 1, characterized in that the first layer is a layer which emits light under the influence of an electrical current.
5. Device according to claim 1 inclusive, characterized in that there is applied to one of the second and third layers mentioned an eighth layer which is made of a photoconducting material, and there is applied to the eighth layer a ninth layer
which is made of a transparent, electrically conducting material.
6. Device according to claim 5, characterized in that the other layer of said second and third layers is provided with electrical conductors extending exclusively in a direction perpendicular to the plane.
7. Device according to claim 6, characterized in that a sixth layer which is made of an electrically insulating material is situated between the other layer of the second and third layers mentioned and the first layer.
8. Device according to claim 5, further comprising a light source for generating a light beam for exposing locations of the eight layer.
9. Device according to claim 1 characterized in that a light-sensitive layer is applied on the side of the device where the other layer of the second and third layers is located.
10. Method of manufacturing a device for displaying information, comprising at least:
a first layer which extends in one plane and is composed of a material whose optical properties vary under the influence of an external electrical control system in such a way that either the transparency of portions selected with the electrical
control system of the first layer for light incident thereon varies or portions selected with the electrical control system of the first layer emit light;
a second and a third layer which extend substantially parallel to the plane, are situated on either side of the first layer and impart to the device a certain desired rigidity, at least one of the second and third layers having a first
conductivity and being provided with at least one electrode and with electrically conducting channels which are extending exclusively in a direction perpendicular to the plane, said channels having a second conductivity substantially larger than the
first conductivity, said at least one electrode electrically contacting at least one of said channels,
wherein said at least one electrode has a minimum dimension (D) in a contact area with said at least one of the second and third layers, mutual distances between at least some adjacent ones of the plurality of channels being smaller than said
minimum dimension (D) of said at least one electrode and wherein a maximum mutual distance between all adjacent ones of the plurality of channels are smaller than said minimum distance (D) of said at least one electrode, the method comprising the
following steps:
a. selecting said at least one of the second and third layers from a material which has a predetermined original conductivity but which can be changed substantially by illuminating it with radiation of a predetermined wavelength;
b. providing a mask on said at least one of the second and third layers, said mask being provided with a plurality of portions non-transparent to radiation of said predetermined wavelength, the spacings between the plurality of portions
corresponding to the mutual distances between adjacent ones of the plurality of channels;
c. illuminating said mask with radiation of said predetermined wavelength;
d. terminating said illumination and removing said mask;
e. attaching said layer to the first layer.
11. Method according to claim 10 wherein said material comprises either PANi/CSA or PANi/DBSA.
12. Method of manufacturing a device for displaying information, comprising at least:
a first layer which extends in one plane and is composed of a material whose optical properties vary under the influence of an external electrical control system in such a way that either the transparency of portions selected with the electrical
control system of the first layer for light incident thereon varies or portions selected with the electrical control system of the first layer emit light;
a second and a third layer which extend substantially parallel to the plane, are situated on either side of the first layer and impart to the device a certain desired rigidity, at least one of the second and third layers having a first
conductivity and being provided with at least one electrode and with electrically conducting channels which are extending exclusively in a direction perpendicular to the plane, said channels having a second conductivity substantially larger than the
first conductivity, said at least one electrode electrically contacting at least one of said channels,
wherein said at least one electrode has a minimum dimension (D) in a contact area with said at least one of the second and third layers, mutual distances between at least some adjacent ones of the plurality of channels being smaller than said
minimum dimension (D) of said at least one electrode, and wherein a maximum mutual distance between all adjacent ones of the plurality of channels are smaller than said minimum distance (D) of said at least one electrode, the method comprising the
following steps:
a. applying a matrix material containing solvent and a conductor additive to a substrate;
b. applying an electrical field perpendicular to the substrate and evaporating the solvent at least virtually simultaneously so that the matrix material acquires a solid structure and the semiconductor additive forms conducting molecular
structures in a direction at least virtually parallel to the electrical field;
c. removing the substrate;
d. attaching the solid structure and the semiconductor additive to the first layer.
13. Method of manufacturing a device for displaying information, comprising at least:
a first layer which extends in one plane and is composed of a material whose optical properties vary under the influence of an external electrical control system in such a way that either the transparency of portions selected with the electrical
control system of the first layer for light incident thereon varies or portions selected with the electrical control system of the first layer emit light;
a second and a third layer which extend substantially parallel to the plane, are situated on either side of the first layer and impart to the device a certain desired rigidity, at least one of the second and third layers having a first
conductivity and being provided with at least one electrode and with electrically conducting channels which are extending exclusively in a direction perpendicular to the plane, said channels having a second conductivity substantially larger than the
first conductivity, said at least one electrode electrically contacting at least one of said channels,
wherein said at least one electrode has a minimum dimension (D) in a contact area with said at least one of the second and third layers, mutual distances between at least some adjacent ones of the plurality of channels being smaller than said
minimum dimension (D) of said at least one electrode, and wherein a maximum mutual distance between all adjacent ones of the plurality of channels are smaller than said minimum distance (D) of said at least one electrode, the method comprising the
following steps:
a. printing a matrix material containing solvent and a conductor additive at predetermined locations of a substrate;
b. evaporating the solvent so that the matrix material acquires an electrically conducting, solid structure;
c. printing insulation material containing a further solvent on the substrate at locations situated outside the predetermined locations;
d. evaporating the further solvent so that the insulation material acquires an electrically conducting, solid structure;
e. removing the substrate;
f. attaching the insulation material and the matrix material with conductor additive to the first layer.
14. A display element, comprising:
a first layer comprising a material whose optical properties can be controlled by application of an electrical field;
second and third conductor layers arranged on opposite sides of the first layer so that an inner surface of each of the conductor layers is in contact with the first layer, each of the conductor layers being generally planar and generally
parallel to the first layer, each of the second and third layers comprising a plurality of electrically conducting channels arranged in an insulating material, each of the electrically conducting channels being arranged generally perpendicular to the
first layer and extending from the inner surface to an opposite outer surface of said conductor layer;
a plurality of contacts arranged on the outer surfaces of the conductor layers, each of the contacts being in electrical contact with a plurality of the electrically conducting channels;
wherein the contacts are arranged so that application of voltages to the contacts on opposite sides of the display element results in the voltages being applied to the first layer through the electrically conducting channels so as to control the
optical properties of portions of the first layer between the contacts.
15. The display element of claim 14, wherein there are a plurality of the contacts arranged on each of the outer surfaces. |
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Claims |
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Description |
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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.sup.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
.mu.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.sup.-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 arises both as a result of discharge as a consequence of static electricity and as a result of other types of damage.
The controlling layers 2, 2' are generally composed of indium/tin oxide structures and/or thin-film transistors and/or metal/insulation/metal structures and/or diodes. Polyimide is often used as insulating layer 4, 4'. High temperatures are
used during the process for applying the last-mentioned layer, which is an additional hazard for the satisfactory operation of the thin-film transistors, the metal/insulation/metal structures and/or diodes.
The devices disclosed in WO-A-96/04585 referred to above and which are provided with active matrices on the outside surfaces of the LCD cell substrates at least partly solve these problems related to the conventional LCD design. However, still a
pattern of individual, transparent electrodes is applied on the inside surface of the LCD cell substrate according to this prior art document. These internal electrodes are connected to the active matrix on the outside of the surface by means of thin
conductive leads. Each internal electrode is connected to one single thin conductive lead, whereas each of the thin conductive leads is also connected to one of a series of conductive leads applied to the outside surface of the LCD cell substrate and
contacting the active matrix.
No manufacturing details with respect to producing the thin conductive leads in the LCD substrate are given. No other production methods than multi-mask steps vacuum technology in general is referred to. Therefore, the suggested method of
producing the devices of WO-A-96104585 necessarily includes extremely difficult alignment steps for properly aligning the thin conductive leads through the LCD substrate with the internal transparent electrodes and the external conductive leads.
Especially, it seems difficult if not impossible to transport unfinished LCD's to a customer without having an active matrix on the outside surface of the LCD substrate and leave it to the customer to apply the active matrix on the outside surface of the
LCD substrate in correspondence with his needs. Without undue costs, costumers will not be able to apply their desired active matrix in proper alignment with the thin conductive leads through the substrate.
The primary object of the present invention is to provide a substrate with at least one electrode, the substrate being provided with electrical leads perpendicular to its surface and allowing electrical connection between at least one electrical
lead and the electrode without complex alignment procedures.
For this purpose, a substrate of the type mentioned at the outset is characterised in that the at least one electrode has a predetermined minimum dimension in a contact area with the substrate, and that mutual distances between adjacent ones of
the plurality of channels are smaller than said minimum dimension of said at least one electrode. Then, no matter where the at least one electrode is contacting the substrate it will always contact at least one of the channels. This greatly reduces
alignment problems.
Preferably, the mutual distances are at most two times smaller than the minimum dimension of at least one electrode.
Even more preferably, the mutual distances are at most ten times smaller than the minimum dimension of the at least one electrode.
The plurality of electrically conducting channels may either be distributed in accordance with a regular pattern or randomly through the substrate.
In one embodiment, the mutual distances are smaller than 3.5 .mu.m.
A further object of the invention is to provide a device for displaying information, for example an LCD, which can be transported to customers without the pattern of controlling layers necessarily already having been applied on the substrate and
still providing customers with the possibility to apply the pattern of controlling layers on locations desired by them without undue costs and complexity.
A still further object of the invention is to increase the yield of the production of such devices.
To that end, the invention also relates to a device for displaying information, comprising at least:
a first layer which extends in one plane and is composed of a material whose optical properties vary under the influence of an external electrical control system in such a way that either the transparency of portions selected with the electrical
control system of the first layer for light incident thereon varies or portions selected with the electrical control system of the first layer emit light;
a second and a third layer which extend substantially parallel to the plane, are situated on either side of the first layer and impart to the device a certain desired rigidity, at least one of the second and third layers being provided with at
least one electrode and with electrically conducting channels which are conductive exclusively in a direction perpendicular to the plane, said at least one electrode electrically contacting at least one of said channels,
characterized in that said at least one electrode has a predetermined minimum dimension in the contact area with said at least one of the second and third layers, and that mutual distances between adjacent ones of the plurality of channels are
smaller than said minimum dimension of said at least one electrode.
Such a structure has sufficient rigidity to be able to be transported to customers without the ultimately necessary conductor patterns having already been applied. The conductor patterns can be applied by the customer himself on the outside of
the second and/or third layer. The conducting channels in the second and/or third layer then ensure that an electrical voltage and/or current whose positions are defined by the pattern of conductors is transmitted to the first layer. The narrower the
small channels and the closer together they are situated, the greater the resolution will be.
A further advantage is that, if the pattern of conductors is not correctly applied to the structure thus defined, said pattern can easily be removed without the device as a whole having to be discarded. After removal, the pattern can be applied
again. This will appreciably increase the production yield.
The device according to the invention may be a component of an LCD, in which the first layer is a liquid-crystal layer, provided with spacers and in which there is situated between said one of the said second and third layers and the first layer
a fourth layer which is made of an electrically insulating material. Said liquid-crystal layer may be of the nematic or smectic type, depending on the desired use. Nematic liquid-crystal layers require a continuous drive in order to be able to have a
memory function. This requires suitable electronics, comprising, for example, metal/insulator/metal structures, thin-film transistors, diodes and conductors. Smectic liquid-crystal layers have a spontaneous memory function.
As an alternative, such an LCD may have a polymer dispersed liquid-crystal layer as first layer, a fourth layer which is made of an electrically insulating material being situated between said one of the second and third layers and said first
layer.
As a further alternative, the device according to the invention can be designed so that the first layer emits light under the influence of an electric current.
The device according to the main claim of this invention defined in this way and according to the variants mentioned thereof then forms an unfinished plate of material which can subsequently be provided by the user with the necessary
application-dependent conductor tracks and electronics. Such an unfinished device can therefore be made as a standard and not in an application-dependent way. This increases the flexibility of the possible applications.
In some applications, not only said one of the second and third layers, but also the other, will have a pattern of electrical conductors which is such that the electrical conductivity of the conductors is directed exclusively in a direction
perpendicular to the plane.
In one of the embodiments of the device according to the invention, there is applied to said one of the said second and third layers a photoconducting layer, to the outside of which a transparent electrically conducting layer has been applied.
Such a device can be used as electronic paper.
In the case of the device last mentioned, a light source, for example a laser, can be provided to generate a light beam for exposing predetermined locations in the photoconducting layer. Such a device forms a laser-beam display.
The device defined above which is provided with a photoconducting layer to which a transparent, electrically conducting layer has been applied can be used with a laser for manufacturing a mask for photolithographic purposes. The advantage of
such a mask is that the locations which are or are not transparent to light can always be defined again without altering the position of the device. Such a mask can therefore advantageously be used in photolithographic processes, because not moving the
mask benefits the accuracy.
The device according to the invention can easily be provided with colours on one of the surfaces by applying a photosensitive layer to the side of the device at which the other of the second and third layers is situated. The locations at which
the layer has to remain as a coloured layer and those at which it has to be removed can then easily be defined with the aid of exposure procedures and chemical development procedures.
Claims 22 to 26 inclusive define methods for manufacturing a layer of material which extends in one plane and is provided with a pattern of electrical conductors extending exclusively in a direction perpendicular to the surface.
The
present invention will be explained in greater detail below by reference to some figures which are intended to illustrate the invention and not to limit the scope of its protection.
FIG. 1 shows a diagrammatic view of a conventional LCD;
FIG. 2 shows the layer structure of a conventional LCD in greater detail;
FIG. 3 shows an LCD having a layer structure according to the present invention;
FIG. 4 shows an alternative structure for the layer structure of FIG. 3;
FIG. 5 shows the application of a light-emitting layer in the device according to the invention;
FIGS. 6a and 6b show alternative embodiments of a device according to the invention which can be used as electronic paper and also as laser-beam display;
FIG. 7 shows a device according to the invention to which a coloured layer has been applied;
FIGS. 8a, 8b, and 8c show diagrammatically the structure of an electrode and a layer which is provided with a pattern of conductors, which conductors extend exclusively in a direction perpendicular to the surface of the layer;
FIGS. 9a, 9b, 9c, 10, and 11 inclusive show alternative methods for forming a layer such as that shown in FIGS. 8a-8c;
FIG. 12 shows the use of a layer as shown in FIGS. 8a-8c as printed circuit board (pcb).
FIG. 3 shows an LCD in accordance with the present invention. In the layer structure according to FIG. 3, the controlling layers 2, 2' have not been
applied directly to the insulating layers 4, 4', but an additional layer 7, 7' is situated in between. Said additional layer is formed from a material in which there are conductors directed exclusively in a direction perpendicular to the surface of the
layers 7, 7'. Such a layer 7 is shown diagrammatically in FIGS. 8a and 8b. The layer 7 is therefore composed of an insulating material 20 which contains small conducting channels 21 which extend exclusively in a direction perpendicular to the surface
of the layer. Preferably, both the insulating layer 20 and the small conducting channels 21 are transparent. The cross section of the small channels 21 and the mutual spacing of the small channels 21 determine the resolution of the device in which the
layer 7 is used.
FIG. 8a shows a perspective view of insulating layer 20 with channels 21, and an electrode 42 which is to be connected to the layer 20 at a predetermined location. FIG. 8b shows the electrode 42 at the predetermined location. The electrode 42
may have any desired shape. However, in accordance with the invention there is a relationship between the dimension of the electrode 42 and the mutual distance between adjacent channels 21 such that no matter where electrode 42 contacts layer 20 it will
always contact at least one channel 21. This reduces alignment problems seriously.
In case electrode 42 has a rectangular shape, as shown in FIG. 8a, with width D and length L, L>D, this condition is met when the mutual distance between adjacent channels 21 is <D. To be sure that a good electrical contact between
electrode 42 and at least one channel 21 will be established, preferably, that mutual distance is at most 1/2.D. Even more preferably, that mutual distance is at most 1/10.D In the arrangement according to FIG. 3, the layer 7 ensures support, which
support was provided in the arrangement according to FIG. 2 by the layer 1. In other words, in the arrangement according to FIG. 3, the controlling layers 2, 2' are situated on the outside of the device. The controlling layers 2, 2' are therefore
applied later than the insulating layers 4, 4'. The high temperatures occurring during the application of the insulating layers 4, 4' and the high electrostatic voltages occurring as a result of the "rubbing" procedure of the insulating layers 4, 4'
therefore no longer have any influence on the controlling layers 2, 2'.
Electrodes of the conducting pattern inside the controlling layer 2 are connected to the small channels 21 inside the layer 7.
FIG. 8c further illustrates this. FIG. 8c shows a cross section through insulating layer 20 with conducting channels 21 above liquid-crystal layer 6. Here, the mutual distance between the channels 21 is much smaller than the dimension D of
electrode 42. A voltage applied on electrode 42 will be transmitted, as it were, perpendicular in the direction of liquid-crystal layer 6 and be present at the terminating portions of the channels 21 at the interface between layer 7 and layer 6.
Therefore, in an area indicated by "A" in FIG. 8c a plurality of channels present an electrical voltage to the liquid-crystal layer 6, thus forming a kind of virtual electrode. Therefore, there is no need to apply an additional electrode in area A to
present the voltage to liquid-crystal layer 6. This facilitates the manufacturing process of liquid crystal display devices. Moreover, locations where voltages need to be presented to liquid-crystal layer 6 are only determined by the location of
electrodes 42 on the outside surface of the layer 7, which facilitates achieving a desired resolution. The number of channels and there mutual distances, as well as the size of the electrodes 42 determine the resolution actually obtained.
The device according to FIG. 3 can be marketed without the presence of the controlling layers 2, 2'. Such a device thus comprises only the layers 7, 4, 6, 4', 7' and still has a universal possible application. Any user can apply the pattern of
conductors he desires by means of the controlling layers 2, 2'.
It is also possible to market a structure in which only one of the layers 7, 7' is applied. The layer 7' is then, for example, absent. At the point where the layer 7' is situated, a user can apply a transparent conducting pattern according to
his own design.
FIG. 4 shows an alternative to such an unfinished LCD structure. In place of the liquid-crystal layer 6 having spacers 5, the device according to FIG. 4 is provided with a polymer dispersed liquid-crystal layer 8.
It is obvious that one of the two layers 7, 7' can be replaced by a transparent, completely electrically conducting layer also in the arrangement according to FIG. 4.
The devices according to FIGS. 3 and 4, or the variants thereof indicated above, can be provided on one side thereof with a light-reflecting layer. This produces light-reflecting LCDs. Light-reflecting LCDs provide a more natural viewing
characteristic, are less tiring and are superior to conventional viewing screens in the event of increase in the illumination level. Information presented by light-reflecting LCDs is also more readily absorbed by users than information presented by
transparent LCDs and/or light-emitting LCDs.
FIG. 5 shows a device according to the invention in which a light-emitting layer 11 is applied instead of a liquid-crystal layer 6 having spacers 5 or a liquid-crystal layer 8. Said light-emitting layer 11 has the property that it emits light at
those locations at which an electrical voltage is applied perpendicularly to the surface of the ligh | | |
