Liquid crystal (LC) cell devices comprise LC material contained between working surfaces of two half-cell components. A LC cell device typically includes electrical terminals at the working surface of one half-cell component for controlling the device by external electrical signals; and with reference to Figure 5, the two half cell components 102, 104 are configured such that an electrical terminal region 101 at the working surface of one half-cell component is not covered by the other half-cell component.

The inventors for the present application have conducted research around the connection of external components to an LC cell.

There is hereby provided a method, comprising: providing a LC cell comprising LC material contained between two components including at least one plastics film component, wherein the LC material is contained laterally by one or more seals; applying an external flexing force to forcibly flex apart the two components in a contact region laterally outwards of the one or more seals; thereafter inserting a distal end portion of a connecting element between the two components; and releasing the external flexing force, to allow the two components to press the connecting element therebetween, with one or more l conductors of the connecting element at the distal end portion aligned with one or more conductors of one or more of the two components at the contact region.

According to one embodiment, the connecting element comprises conductors on both sides, which make electrical contact with conductors on both the two components.

There is also hereby provided a device, comprising: a first LC cell comprising LC material contained between two components including at least one plastics film component, wherein the LC material is contained laterally by one or more seals that bond the two components together; and a connecting element having a distal end portion pressed between the two components in a contact region laterally outwards of the one or more seals; wherein one or more conductors at the distal end portion of the connecting element are aligned with one or more conductors of one or more of the two components at the contact region.

According to one embodiment, the connecting element comprises conductors on both sides at the distal end portion; and the conductors on both sides at the distal portion of the connecting element make electrical contact with conductors on both the two components.

An example embodiment is described in detail hereunder, by way of example only, with reference to the accompanying drawings, in which: Figure 1 illustrates the provision of a LC cell device according to a first example embodiment;

Figure 2 illustrates manipulation of the LC cell device of Figure 1 , according to an example embodiment of the present invention;

Figure 3 illustrates the LC cell device of Figure 1 with electrical connections to an external component; and

Figure 4 illustrates the size and alignment of the two half-cell components of the LC cell of Figure 1.

With reference to Figure 1 , a LC cell device according to a first example embodiment comprises LC material 20 contained between two half-cell components 2, 4. A frame of adhesive sealant material 6 outside the active area of the device functions to laterally contain the LC material 20 and to bond the two half-cell components 2, 4 together. The inner perimeter of the frame of adhesive sealant material 6 defines the boundary of the active area. The LC material 20 is interspersed with spacers 18, which function to improve the uniformity of thickness of the LC material 20 over the active area. In this example, the spacers 18 form an integral part of one of the half-cell components 2, 4; but the spacers may also comprise a random scattering of pre-prepared spacer elements. Figure 4 shows how the two half-cell components 2, 4 have the same size (area and perimeter), and are aligned such that all corners coincide with each other.

Each half-cell component 2, 4 comprises a thin plastics support film 8, such as an optically neutral (non-birefringent) organic polymer film. In this example, the plastics support film 8 comprises a cellulose triacetate (TAC) film having a thickness between about 10 and 100 microns.

In this example, the LC cell is for a relatively simple device (such as a switchable privacy screen) whose primary function is to simply switch the whole of the active area from a transparent state (at least in a direction substantially perpendicular to the plane of the LC cell) to a non-transmissive state (at least in a direction substantially perpendicular to the plane of the LC cell). Each half-cell component 2, 4 comprises: (i) a planarisation layer 10 formed in situ on the plastics support film 8: (ii) a conductor layer 14 formed in situ on the plastics support film 8 after the planarisation layer; and (iii) a LC alignment layer 16 formed in situ on the plastics support film 8 after the conductor layer 14. In this example, one of the half-cell components 2, 4 further comprises (iv) a patterned spacer material layer formed in situ on the plastics support film 8 after formation of the conductor layer 14 and before formation of the LC alignment layer 14. The patterned spacer material layer defines an ordered array of spacers 18 over at least the active area. One or both of the half-cell components may comprise additional layers formed in situ on the plastics support film 8.

In this example, the planarisation layer 10 comprises an organic polymer layer formed from a film of solution deposited onto the plastics support film 8.

In this example, the conductor layer comprises a conductor layer with a high white-light transmittance, such as a thin conductive metal oxide layer, such as a thin indium-tin-oxide (ITO) layer. The thin ITO layer 14 is formed by a vapour deposition technique such as sputtering.

In this example, the spacer structure material layer is formed from a deposited film of a solution of a material that can be converted into a cross-linked organic polymer. A radiation image of the pattern desired for the array of spacer structures 18 is used to initiate the cross-linking. For example, the radiation image is at a frequency that induces the generation of species that achieve the cross-linking in a subsequent heating step. The resulting latent solubility image (created by the pattern of insoluble, cross-linked areas and soluble, non-cross- linked areas) is later developed to produce the array of spacer structures 18.

The LC alignment layers 16 interface the LC material 20 and determine the molecular orientation of the LC material 20 in the absence of an overriding electrical field generated by a voltage between the two conductor layers 14 on opposite sides of the LC material 20. In this example, the LC alignment layer 16 comprises a uniaxially rubbed polyimide layer, but e.g. an irradiation technique can also be used to create a LC alignment layer from a layer of suitable material formed in situ on the plastics support film 8.

In this example, the spacer structures 18 are formed before depositing material for the LC alignment layer 16. In an alternative example, the spacer structures are formed after depositing material for the LC alignment layer, and uniaxial rubbing (or photoalignment) is carried out after forming the spacer structures 18.

In this example, the conductor layer 14 of both half-cell components extends to a contact region beyond the active area and beyond the outer perimeter of the adhesive sealant frame 6.

With reference to Figure 2, the half-cell components 2, 4 are forcibly flexed apart in the contact region while forcibly bracing the two half-cell components 2, 4 in at least the region of the part of the adhesive sealant frame 6 adjacent to the contact region, to reduce the risk of the two half-cell components 2, 4 popping apart. A jig (not shown) is employed to apply an outwardly pulling force on the outer surfaces (non working surfaces) of both the half-cell components 2, 4 in the contact region (using vacuum suction tools to grip the outer surfaces of the half-cell components 2, 4 in the contact region), while bracing the outer surfaces of the half-cell components 2, 4 in at least the region of the part of the adhesive sealant frame 6 adjacent to the contact region. With the two half-cell components 2, 4 forcibly flexed apart in the contact region, an external component 100 is inserted into the expanded space between the two half-cell components 2, 4. With reference to Figure 3, the external component 100 comprises a plastics support film 22 supporting patterned conductor layers/foils 24 on both sides of the plastics support film 22. Protective films 26 protect the patterned conductor layers/foils 24, but the patterned conductor layers/foils 24 are exposed at a distal edge portion of the external component 100. Before inserting the distal edge portion of the external component 100 into the expanded space between the half-cell components 2, 4, a conductive adhesive material 28 is applied to the distal edge portion of the external component 100. For example, the conductive adhesive material 28 may be a conductive paste (such as a paste including silver (Ag) particles) or an anisotropic conductive film (ACF).

Once the distal edge portion of the external component 100 is inserted in place between the two-half cell components 2, 4, the external force flexing the half-cell components 2, 4 apart in the contact region is released, whereupon the elastic resilience of the half-cell components 2, 4 acts to return the half-cell components towards the planar resting configurations out of which they had been forced. In this example, the external component 100 has a thickness greater than the thickness of LC material 20, which prevents the half-cell components 2, 4 from completing a return to the resting configurations. The half-cell components 2, 4 press the external component 100 therebetween. The conductor layers 14 of the half-cell components 2, 4 are in electrical contact with the conductor layers/foils 24 of the external component 100 via the conductive adhesive material 28.

Adhesive material can be added between the two half-cell components 2, 4, after making the electrical connection between the conductor layers on the half-cell components 2, 4 and the conductor layers/foils of the external component, to improve mechanical strength of the resulting assembly.

The proximal end (opposite end to that inserted between the two half-cell components 2, 4) of the external component 100 may be connected to a power source to drive the LC cell.

In another example, the external component 100 comprises a conductor layer/foil 24 on only one side of the plastics support film. This conductor layer/foil 24 defines two terminals, and the conductor layer 14 of one of the half cell components is patterned to define two terminals: one terminal in electrical series with the part of the conductor layer in the active area; and the other terminal providing an electrically parallel connection to the conductor layer 14 of the other half-cell component via e.g. a conductive adhesive in a region outside the active area of the LC cell. Polariser components (not shown) are applied to opposite sides of the LC cell. In this example, the device is a privacy screen for e.g. display monitors. A change in the voltage between the two conductor layers blanket switches the whole active area between transmissive and non-transmissive states for a range of side view angles (e.g. angles greater than about 40 degrees relative to the normal (perpendicular to the screen). In more detail, for the above-mentioned range of side view angles, a change in the voltage between the two conductor layers 14 switches the LC material between (i) a state that transmits external light through both polarizer components, and (ii) a state that does not transmit external light through both polarizer components.

Since there is no need to have one part of one half-cell component uncovered by the other half-cell component, the technique described above has the advantage that production does not require the supply of plastics support films of different sizes or special equipment for pre-assembly cutting of single-size plastics support films without causing burring. Burring caused by low quality cutting can result in poor cell assembly. Furthermore, there is less risk of the external component 100 becoming detached from the LC cell during operator handling in later operations such as device testing and packaging, whereby further increases in yield can be expected. Furthermore, for the specific example described above involving conductor layers/foils 24 on both sides of the external component 100, there is the advantage of not including in the LC cell an electrical connection between the two half-cells, such as an electrical connection via the adhesive sealant 6.

In the example described above, the LC cell is for a relatively simple device, but the technique is also applicable to more complex devices such as passive matrix displays or even active matrix displays.

As mentioned above, an example of a technique according to the present invention has been described in detail above with reference to specific process details, but the technique is more widely applicable within the general teaching of the present application. Additionally, and in accordance with the general teaching of the present application, a technique according to the present invention may include additional process steps not described above, and/or omit some of the process steps described above.

In addition to any modifications explicitly mentioned above, it will be evident to a person skilled in the art that various other modifications of the described embodiment may be made within the scope of the invention.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features.

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