Application of an Electro Spray Deposition (ESD) Method to Control the Pre-Tilt Angle in a Nematic LC Cell

Abstract

We applied the ESD technique to form an aligned LC layer with controlled pre-tilt angle. First, a horizontally aligned film was formed on the glass substrate by coating and rubbing. Then, a material promoting vertical alignment was sprayed using the ESD method. The aligned layer consisted of very fine domains mingled with horizontally and vertically aligned part. We were able to control the pre-tilt angle in a wide range by varying the amount of sprayed solution of the aligning material.

Control of Pre-tilt Angle and Evaluation of Azimuthal Anchoring Strength Considering the Pre-tilt Angle on the Alignment Film Formed by the ESD Method

“…However, maybe the inducing pre-tilt angle does not show the good repeatability because the liquid separation occurs due to the difference of the specific gravity for each solution. The ElectroSpray Deposition (ESD) is one of the film forming methods by using the electric field and electric charges has been proposed by V. N. Morozov et al [2][3][4][5][6][7][8][9] And, a hybrid method which is a combination of the spin-coat and the ESD has been proposed by our group [10] for the control of pre-tilt angle in the LC cell. The special alignment film consisted of innumerable tiny multi-domains with the horizontal and vertical alignment materials can be formed by this method.…”

Quasi-Black Mask for Low-Cost LCDs by Patterned Alignment Films Formed by an Electro-Spray Deposition Method

“…In previous studies, our research group has investigated the application of the ESD method for forming liquid crystal (LC) alignment films [14]- [16]. When the ESD method was used to form an alignment film comprising numerous small domains with two types of alignment materials for the horizontal and vertical alignment, the pretilt angle was controlled using simple equipment in the atmosphere [15].…”

Control of the pretilt angle for liquid crystal alignment using novel electrospray deposition methods with two capillaries

“…Our conventional ESD process that uses two kinds of alignment materials is performed as follows: one of the alignment films is first formed by the spin‐coating method, and another type of alignment material is subsequently sprayed by the ESD method. However, we encountered a problem with this method when some domains grew to diameters of 100 µm when the sprayed material was oversupplied . A schematic of this process is shown in Fig.…”

“…(a). Therefore, we took measures to solve this problem, which led to our proposal of novel methods . We observed that, when two solutions with alignment materials were sprayed using two capillaries and each solution was simultaneously or alternately sprayed in time using each capillary, the effective mingle proportion of the two types of particles (domains) on the film surface was constant, even if the volume distribution was nonuniform during the deposition process, as shown in Fig.…”

“…However, we encountered a problem with this method when some domains grew to diameters of 100 μm when the sprayed material was oversupplied. 16 A schematic of this process is shown in Fig. 1 (a).…”