Patent ID: 11927863
Assignee: COMMISSARIAT A L'ENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 16:
17. A method for addressing a light beam phase modulation device, the addressing device comprising a matrix of elementary cells, called pixels, coupled to an addressing circuit for said pixels, each elementary cell comprising a liquid crystal layer (CL) and, on either side of said liquid crystal layer, at least one first electrode (ELP) called pixel electrode controlled by a control transistor coupled to said addressing circuit, and a second electrode (EL2) that is transparent and common to all the cells, the liquid crystal being composed of molecules that have a natural orientation of rest in a plane of said layer in a so-called horizontal alignment direction (Xa) oriented along a so-called horizontal row of pixels, and in the absence of voltage between the pixel electrode and the second electrode, and another orientation outside of said plane of said layer, in the presence of voltage between the pixel electrode and the second electrode, called activation voltage (Vacc), the device further comprising a set of so-called lateral electrodes extending in a so-called vertical direction (Y) at right angles to said alignment direction (Xa) and disposed on a same plane as the pixel electrode, the method comprising:
an activation phase wherein, for each pixel, said activation voltage is applied,
an accelerated relaxation phase wherein, for each pixel, a so-called acceleration voltage (Vacc) is applied, via at least two lateral electrodes, generating a lateral electrical field (Era) substantially parallel to said alignment direction, in a vector allowing an accelerated return of the liquid crystal molecules to their orientation of rest, said acceleration voltage being applied when the activation voltage is no longer applied
wherein, for each pixel, the pixel electrodes and the lateral electrodes are combined and called elementary electrodes, said elementary electrodes taking the form of a strip of substantially identical dimensions and extending in the vertical direction, said elementary electrodes being divided up into a first group and a second group of one strip in every two, and wherein:
during the activation phase, the activation voltage is applied via the elementary electrodes in combination with the second electrode, and
the accelerated relaxation phase comprises two sequences:
a first sequence wherein the acceleration voltage is applied via the first group of elementary electrodes, the elementary electrodes of the second group being connected at high impedance or to a reference potential, and
a second sequence wherein the acceleration voltage is applied via the second group of elementary electrodes, the elementary electrodes of the first group being connected at high impedance or to a reference potential.