Rubbing cloth

For pieces too large to fit in the pot, try rubbing lightly with a paste of baking soda and water, using aluminum foil as your rubbing cloth. 

Aerie etal. reported that the phase retardation increased steadily with pile impression. The influence of the pile impression of the rubbing cloth on the rubbing-induced optical retardation Fr of the orienting layer, and on the normal force Fn exerted by the rubbing cloth on the samples is shown in Fig. 2.7. 

Pig. 2.20 Structural sketch of a rubbing machine. A rubbing machine consists of a roller covered by rubbing cloth, and a platform to hold the substrate. The roller or the substrate stage moves at a constant speed while the roller is rotating at several hundreds of rpm. The gap between the roller and the stage is adjusted to change the pile impression. 

Here, mi, a, and Y are the effective contact density between the alignment material and the rubbing cloth, the contact area, and the jneld stress of the alignment material. If we assume that the contacts of the fibres of the rubbing cloth and the alignment material are a series of point contacts by a single fibre as shown in Pig. 2.23,... 

The rubbing machine is covered with a hood, and an exhaust fan is used to prevent the diffusion of the dust from the rubbing cloth and alignment material. After the rubbing process, a cleaning process is used to wash away particles of the rubbing cloth and alignment material from the surface of the substrate. 

Since bits of the rubbing cloth and pieces of alignment material are embedded on the substrate by the rubbing process, a cleaning step is required after rubbing. The substrates are cleaned by using a normal process with purified water and ultrasonic vibration, and then dried. 

Table 2.4 summarizes specifications for rubbing cloths used for display manufacturing. The groove structure caused by rubbing resembles the structure of the textile of the rubbing cloth, and this has secondary effects on the alignment of the LC. 

Rubbing Technologies Mechanisms and Applications Table 2.4 Specifications for rubbing cloths in the market... 

Contact length of rubbing cloth Rubbing pressure Initial texture... 

STN-LCD. The cylinder is wrapped with the rubbing cloth and was the first dry cloth machine. Up to then, the American RCA company and Jim Fergson at ILIXCO used a wet process with organic solvents and surfactants. The basic approach of mbbing machine shown in Fig. 3.7 is used as a standard technique in LCD factories today [10]. 

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