Sharp Kabushiki Kaisha Corporation

New Transducers Limited

Nct Group, Inc.

Gillian Margaret Davis

Kathryn Walsh

Paul May

Duncan James Anderson

Robert George Watling Brown

Nathan James Smith

Robert George Brown

Claire Blay

Anthony Malcolm McDonald

Masayuki Nakazawa

Thomas Lundie

Robin Meredith Courtney Pain

Martin James Stone

Anderson James Duncan

A cholesteric film is formed into an optical device comprising a plurality of layers. The cholesteric film is initially placed in a first predetermined state, for instance heating to a first predetermined temperature, and is then irradiated with narrow band UV radiation. The properties of an upper layer of the film are fixed, for instance for reflecting normally incident infrared radiation of a particular handedness. This process is repeated for different wavelengths of UV fixing radiation so as to penetrate to different depths from the surface of the film in order to form the layers. This method may be used to produce a filter of reduced sensitivity to angle of incidence. In addition to the infrared reflecting layer, red and green reflecting layers are provided. For normally incident radiation, the red and green layers reflect red and green parts R and G, whereas the blue part B of the spectrum is transmitted. For off-axis illumination or viewing, the red part R is reflected by the infrared layer and the green part G is reflected by the red layer. The birefringence of the infrared layer and the red layer reverses the direction of circular polarisation of the blue part B, which thus passes through the green layer.

Optical radiation filter

An electrically controllable grating is provided by forming regions and of different refractive index within an electro-optic material. Electrodes are provided so that a readily controllable electric field may be applied to the index grating formed by the alternating regions such that the refractive index of the regions may be varied electrically to form a controllable grating. The grating may be used as an electrically controllable distributed Bragg reflector to allow variable wavelength feedback within a laser cavity. The grating may be used to perform wavelength division multiplexing and/or frequency modulation.

Electrically controllable grating, and optical elements having an electrically controllable grating

A loudspeaker, for example, for an in-vehicle hands-free commnunication system or an in-vehicle entertainment system is provided as part of a vehicle sun visor ( ), or as an attachment ( ) to a vehicle sun visor so that the loudspeaker can be placed relatively close to the driver's ears and in front of the driver. Accordingly, there will not be any significant tendency for the driver to turn their head when listening to the loudspeaker. The loudspeaker comprises a flat panel ( ) which is driven by a piezo-electric actuator ( ), enabling an extremely thin construction to be realised and the loudspeaker to be conveniently integrated into the sun visor, or provided as an unobtrusive attachment for the sun visor.

Vehicle loudspeakers

Filter and method of making an optical device

An electro-acoustic transducer comprises first and second panels (,A,,B) each of which can be vibrated to generate sound, a frame (,) for mounting the panels, and first and second seals (,A,B) arranged between the frame and the edges of the panels for holding the panels in the frame, substantially isolating the frame acoustically from the edges of the panel, and substantially sealing the frame to the edges of the panel. One or more actuators (,), such as piezoelectric elements, are provided for receiving a driving signal and vibrating in response thereto, and the actuators are mechanically and acoustically coupled to the first panel at one or more locations remote from the edges of the first panel so that the first panel vibrates in response to vibration of the actuators. The second panel is mechanically and acoustically coupled to the first panel and/or to the actuators at one or more locations remote from the edges of the second panel so that the second panel also vibrates in response to vibration of the actuator means. The acoustic properties of the panels, the seals, the actuators and the couplings can be chosen to obtain a required frequency response from the transducer. Different embodiments are described in which the panels are driven in phase, in anti-phase, and in a more complex manner.

Electroacoustic transducers comprising vibrating panels

A broadband cholesteric optical device such as a polarizer or a spectral filter includes a broadband cholesteric layer, for instance, of a graded pitch type such that the cholesteric pitch increases monotonically from one surface of the film to the other surface. In order to improve the off-axis performance, a compensator is provided in the form of a positive birefringence film whose optic axis is substantially perpendicular to the film. Another negative birefringence film whose optic axis is also perpendicular to the film may also be provided.

Broadband cholesteric optical device having a broadband cholesteric layer, a positive C-plate and a negative C-plate

A broadband cholesteric polariser includes at least one pair of adjacent layers. The at least one pair includes a cholesteric layer and a compensating layer. The compensating layer has a refractive index perpendicular to the compensating layer greater than a refractive index oriented within the compensating layer.

Broadband cholesteric polarizer and an optical device employing the same

An illumination system includes a polarization selective holographic element, which includes at least one optically anisotropic material, arranged to separate light of a first polarization type from light of a second polarization type, and converting section for converting light of at least one of the first and second polarization types to light of a common polarization type. Where the polarization selective holographic element separates two orthogonal components of plane polarized light from one another, the converting section can include a polarization rotator, for example a half wave plate, or alternatively a quarter wave plate and a reflector arranged to reflect light back through the quarter wave plate. Where the polarization selective holographic element separates opposite handed components of circularly polarized light, the converting section can include a reflector.

Illumination system and display device

An illumination system includes a polarized light source which emits circularly polarized light of a particular handedness and a cholesteric filter having a region arranged to transmit circularly polarized light falling within a first wavelength band and to reflect other wavelengths of circularly polarized light. A reflector redirects the reflected light back towards the cholesteric filter. The cholesteric filter can include a first layer having portions which reflect red, green and blue light while transmitting other colors, and a second layer identical to the first layer but out of alignment therewith so that each region of the filter transmits only one color of light, the other colors being reflected.

A film of photosensitive material is illuminated from first and second sides with coherent polarized light so as to form an interference pattern within the film. Regions of cyclicly varying refractive index are provided in the film in accordance with the intensity of the interference patten, thereby forming an polarization sensitive refractive index grating. The refractive index grating may be used as a polarization and wavelength dependent mirror, patterned polarizer, beamsplitter or filter.

Polarization sensitive devices and methods of manufacture thereof

An illuminator includes a light guide in the form of a light pipe, one surface of which is provided with a polarization separating layer in the form of an anisotropic layer for separating substantially all of the light of one polarization from the orthogonal polarization component. The anisotropic layer is provided between the light pipe and a reflector. The layer has a first refractive index greater than or equal to that of the light pipe and a second refractive index less than that of the light pipe.

Illuminator with polarization separating anisotropic layer between light

A birefringent element is patterned such that for light of a first polarisation the element acts as a first refractive optical element and for light of a second polarisation the optical response of the element changes. The element can be used in conjunction with a polarisation selecting means, such as a liquid crystal device, to provide an electrically controllable optical element that can be used in light beam manipulation applications.

Polarisation dependent refractive device exhibiting independtly varying

An electro-optic material has first and second regions formed therein. The optic axes of the first and second regions are antiparallel and define a domain inversion pattern. The difference in refractive index between the first and second regions is a function of an electric field applied thereto. The difference in refractive index enables spatial light phase modulators and refractive optical devices having electrical control to be formed.

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Huntingdon, United Kingdom

Gillian Margaret Davis