BACKGROUND

Field

The present invention relates to electroactive optics and lenses using such optics and, in particular, to flexible liquid crystal cells and lenses.

Description of Related Art

As soft contact lenses are handled by contact lens wearers, they are subject to deformation. In some cases, the lenses may be folded in half over short folding radii, as small as 2 millimeters or so. Thus, the soft contact lens should be flexible enough to endure this deformation without damage over reasonable useable lifetime. It is desirable also that the lens be elastic in the sense that it is capable of recovering its size and shape and of retaining the optical properties of the lens after recovering from the deformation. A number of polymers, including hydrogel contact lenses and silicone hydrogel contact lenses, have been developed with flexibility and elasticity in mind.

In electroactive lenses, the electroactive components, such as liquid crystal cells, can be embedded in a lens body made of a flexible and elastic polymer. However, electroactive components can limit both the flexibility and the elasticity of the lens body as a whole.

It is desirable to provide a lens with electroactive components that is both flexible and elastic.

SUMMARY

An electrically tunable lens is described that comprises first and second alignment layers, with an active layer comprising liquid crystal confined between the first and second alignment layers in an optical path of the lens. Embodiments are described in which a first electrode is disposed above the first alignment layer and has a first patterned opening, such as a circular hole, disposed over an aperture region of the active layer. Also a second electrode is disposed below the second alignment layer, and has a second patterned opening arranged to induce, in combination with the first electrode, an electric field in the active layer. The first and second patterned openings can be circular in shape. In some embodiments, the first and second patterned openings have circular shapes with a common radius. In some embodiments, the first and second patterned openings have circular shapes with different radii.

In flexible or elastic versions of the embodiments including first and second electrodes having patterned openings, and in other embodiments described herein, an array of elastic polymer posts is disposed in the active layer, configured to maintain the thickness of the active layer after bending and recovery of its original shape.

Embodiments of the electrically tunable lens described herein can have resistive layers disposed above the first alignment layer and below the second alignment layer to improve dispersion of the electric field lines through the active layer.

One or both of the first and second alignment layers can comprise a polymeric layer including liquid crystal moieties.

In some embodiments, a third alignment layer is disposed between the first and second alignment layers, and a second active layer comprising liquid crystal is confined between the third alignment layer and the second alignment layer. A pad electrode can be disposed between the first and second active layers.

In the embodiment including first and second electrodes having patterned openings, and in other embodiments described herein, a driver can be electrically connected to the first and second electrodes. The driver can be configured to apply a drive signal across the first and second electrodes. In various embodiments, the driver can apply a drive signal having an adjustable duty cycle. The driver can apply a drive signal using pulse width modulation. The driver can apply a drive signal having a DC offset.

In some embodiments, the driver can apply a drive signal that includes an initial higher field power interval followed by a subsequent lower field power interval, where the lower field power interval is configured to establish a target lens power during the lower field power interval. The combination of the higher field power interval followed by the lower field power interval can reduce disclination of liquid crystal moieties in the active layers, particularly near the edges of the aperture region of the lens.

In embodiments described herein, at least one of the first and second alignment layers has an anchoring strength greater than 10−4J/m2. Embodiments are described in which alignment layers comprise polymeric layers including liquid crystal moieties, having an anchoring strength greater than 10−4J/m2. Polymeric layers of this type can be flexible and can be elastic.

Also, an electrically tunable lens is described that comprises first, second, third and fourth alignment layers, having a first active layer comprising liquid crystal between the first and second alignment layers, and a second active layer comprising liquid crystal between the third and fourth alignment layers. The first electrode is disposed above the first alignment layer and has a first patterned opening disposed in alignment with an aperture of the first active layer. A second electrode is disposed below the fourth active layer, and has a second patterned opening disposed in alignment with an aperture of the second active layer. A pad electrode is disposed between the first and second active layers. A driver is electrically connected to the first and second electrodes and to the pad electrode. The driver is configured to apply a first drive signal to the first electrode and a second drive signal to the second electrode. The pad electrode can be maintained at a reference potential such as ground, or otherwise used in the generation of the first and second drive signals. The drive signals are arranged to induce, in combination with the pad electrode, electric fields in the first and second active layers to tune the optical power of the lens. Many of the features discussed above can be applied to this type of electrically tunable lens having two active layers, with outer electrodes having patterned openings and an intermediate pad electrode.

Also, an elastic or flexible, electrically tunable liquid crystal lens is described. The liquid crystal lens includes a cell with a cell gap thickness that is substantially retained after it has been folded and returned to its original shape. Thus, the shape and optical properties of the liquid crystal lens can recover after folding.

Embodiments described include an electroactive cell comprising a liquid crystal in a gap between polymeric alignment layers, with an array of polymer posts disposed in the gap between the alignment layers.

In examples described herein, one or more of the alignment layers comprises a flexible polymeric material including embedded liquid crystal moieties.

Some examples of an electrically tunable lens described herein comprise a first alignment layer and a second alignment layer; an array of elastic polymer posts in a gap between the first alignment layer and the second alignment layer, posts in the array extending from the first alignment layer to the second alignment layer; liquid crystal confined in the gap between the first and second alignment layers around posts in the array; and one or more electrodes arranged to induce an electric field in the liquid crystal.

A polarization-independent example includes a third alignment layer and a second array of elastomer posts in a second gap between the second alignment layer and the third alignment layer, posts in the second array extending from the second alignment layer to the third alignment layer. Also, liquid crystal is confined in the second gap around posts in the second array. The second alignment layer in the example can include liquid crystal moieties having directors aligned orthogonal to an optical path and parallel near a first surface adjacent to the first mentioned gap, and directors aligned orthogonal to an optical path near a second surface adjacent to the second mentioned gap and orthogonal to the directors near the first surface.

Methods for manufacturing flexible liquid crystal cells are described, including formation of polymer posts in liquid crystal layers by photo-polymerization according to a pattern. In an embodiment described herein, the method includes assembling a first flexible alignment layer and a second flexible alignment layer with a gap therebetween; forming flexible or elastic polymer posts extending across the gap between the first flexible alignment layer and the second flexible alignment layer; and providing liquid crystal material surrounding the posts in the gap. In embodiments described herein, the method includes providing a combination of a liquid crystal material and a polymer precursor material in the gap, and forming the elastic posts by inducing phase separation of the polymer precursor and liquid crystal, and polymerizing the polymer precursor according to a pattern.

Various combinations and additions to the devices and methods are described below.

Other aspects and advantages of the present invention can be seen on review of the drawings, the detailed description and the claims, which follow.

