Electro-optical system containing a compensating film

A process for producing a device for compensating for the optical path difference d.multidot..DELTA.n of an addressable liquid-crystal layer, wherein said device is based on a liquid-crystalline polymer, comprising:

• axially orienting a liquid-crystal polymer, by applying an electrical or magnetic field or by mechanical stress, above the glass transition temperature, and freezing-in this orientation by cooling said liquid-crystalline polymer to a temperature below said glass transition temperature, said liquid crystal polymer being a side-chain polymer containing monomer units of formula I:
• ##STR20## wherein P is a polymer main-chain unit,
• Sp is a bivalent spacer group connecting radical B to polymer main chain, and
• B is an organic "rod-like" radical containing at least two six-membered groups, a "disc-like" radical or a "board-like" radical;
• or
• a liquid crystal elastomer containing 3-dimensionally crosslinked monomer units of formula II:
• ##STR21## wherein P, Sp and B are as defined above, and
• V is a crosslinking unit linking together two adjacent polymer chains.

In a method of compensating for the optical path difference of an addressable liquid-crystal layer, the improvement wherein a liquid-crystalline polymer is used as a means for compensating said optical path difference and said liquid-crystalline polymer is a side-chain polymer containing monomer units of formula I:

• ##STR22## wherein P is a polymer main-chain unit,
• Sp is a bivalent spacer group connecting radical B to polymer main chain, and
• B is an organic "rod-like" radical containing at least two six-membered groups, a "disc-like" radical or a "board-like" radical;
• or
• a liquid crystal elastomer containing 3-dimensionally crosslinked monomer units of formula II:
• ##STR23## wherein P, Sp and B are as defined above, and
• V is a crosslinking unit linking together two adjacent polymer chains.