Twisted nematic liquid crystal display device with retardation plates having phase axis direction within 15.degree. of alignment direction

A liquid crystal display device comprising:

• a first substrate, on one surface of which at least one first electrode and a first aligning film covering said first electrode are formed, said first aligning film covering at least a portion of said one surface of said first substrate and being executed by an aligning treatment in a predetermined first direction;
• a second substrate, on one surface of which a plurality of second electrodes and a second aligning film covering said second electrodes are formed, said second aligning film covering at least a portion of said one surface of said second substrate and being executed by an aligning treatment in a second direction substantially perpendicular to the first direction of the first aligning film of said first substrate;
• a seal member for bonding said first substrate to said second substrate with a predetermined gap therebetween so that the first electrode on said first substrate is opposed to the second electrodes on said second substrate;
• a liquid crystal contained in a region defined by said first substrate, said second substrate and said seal member, and forming a liquid crystal layer in the region, liquid crystal molecules of said liquid crystal being aligned in a state such that they are twisted at substantially 90.degree., and said liquid crystal layer having a refractive-index anisotropy .DELTA.n and a liquid crystal layer thickness d such that the value of a product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the liquid crystal layer thickness d of the liquid crystal is from 350 nm to 700 nm;
• a pair of polarizing plates disposed outside of said first substrate and said second substrate to sandwich the substrates therebetween, a polarizing axis of a first of said polarizing plates being directed toward a direction perpendicular to or parallel to said first direction of the first aligning film of said first substrate, and a polarizing axis of a second of said polarizing plates being directed to cross at substantially a right angle to said first of said polarizing plates;
• a first retardation plate disposed between one of said pair of first and second polarizing plates and said first substrate so that a direction of one of an advanced phase axis and a delayed phase axis thereof is equal to said first direction of the first aligning film of said first substrate or different from said direction within a range from -15.degree. to +15.degree., and said first retardation plate having a refractive-index anisotropy .DELTA.n and a thickness d such that the product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the thickness d is from 300 nm to 600 nm;
• and
• a second retardation plate disposed between said first substrate and one of said pair of first and second polarizing plates adjacent to said first retardation plate so that a direction of a delayed phase axis thereof substantially coincides with a direction perpendicular to the direction of the delayed phase axis of said first retardation plate, and said second retardation plate having a refractive-index anisotropy .DELTA.n and a thickness d such that the product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the thickness d is in a range from 300 nm to 600 nm.

A liquid crystal display device comprising:

• a first substrate, on one surface of which at least one first electrode and a first aligning film covering said first electrode are formed, said first aligning film covering at least a portion of said one surface of said first substrate and being executed by an aligning treatment in a predetermined first direction;
• a second substrate, on one surface of which a plurality of second electrodes and a second aligning film covering said second electrodes are formed, said second aligning film covering at least a portion of said one surface of said second substrate and being executed by an aligning treatment in a second direction substantially perpendicular to the first direction of the first aligning film of said first substrate;
• a seal member for bonding said first substrate to said second substrate with a predetermined gap therebetween so that the first electrode on said first substrate is opposed to the second electrodes on said second substrate;
• a liquid crystal contained in a region defined by said first substrate, said second substrate and said seal member, and forming a liquid crystal layer in the region, liquid crystal molecules of said liquid crystal being aligned in a state such that they are twisted at substantially 90.degree., and said liquid crystal layer having a refractive-index anisotropy .DELTA.n and a liquid crystal layer thickness d such that the value of a product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the liquid crystal layer thickness d of the liquid crystal is from 350 nm to 700 nm;
• a pair of polarizing plates disposed outside of said first substrate and said second substrate to sandwich the substrates therebetween, a polarizing axis of a first of said polarizing plates being directed toward a direction perpendicular to or parallel to said first direction of the first aligning film of said first substrate, and a polarizing axis of a second of said polarizing plates being directed to cross as substantially a right angle to said first of said polarizing plates;
• a first retardation plate disposed between one of said pair of first and second polarizing plates and said first substrate so that a direction of one of an advanced phase axis and a delayed phase axis thereof is equal to said first direction of the first aligning film of said first substrate or different from said direction within a range from -15.degree. to +15.degree., and said first retardation plate having a refractive-index anisotropy .DELTA.n and a thickness d such that the product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the thickness d is from 300 nm to 600 nm;
• and
• a second retardation plate disposed between the other of said pair of first and second polarizing plates and said second substrate so that a direction of a delayed phase axis thereof substantially coincides with a direction perpendicular to the direction of the delayed phase axis of said first retardation plate, and said second retardation plate having a refractive-index anisotropy .DELTA.n and a thickness d such that the product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the thickness d is in a range from 300 nm to 600 nm.

An active matrix liquid crystal display device having thin film transistors, comprising:

• a first substrate, on one surface of which at least one common electrode and a first aligning film covering said first electrode are formed, said first aligning film covering at least a portion of said one surface of said first substrate and being executed by an aligning treatment in a predetermined first direction;
• a second substrate, on one surface of which are formed a plurality of pixel electrodes, a plurality of thin film transistors, and a second aligning film covering said pixel electrodes and said thin film transistors, said thin film transistors being connected to said pixel electrodes and operated by a scanning signal and a data signal to be supplied from a scanning line and a data line of said pixel electrodes, said second aligning film covering at least a portion of said one surface of said second substrate and being executed by an aligning treatment in a second direction substantially perpendicular to the first direction of the first aligning film of said first substrate;
• a seal member for bonding said first substrate to said second substrate with a predetermined gap therebetween so that the common electrode on said first substrate is opposed to the pixel electrodes on said second substrate;
• a liquid crystal contained in a region defined by said first substrate, said second substrate and said seal member, and forming a liquid crystal layer in the region, liquid crystal molecules of said liquid crystal being aligned in a state such that they are twisted substantially 90.degree., and said liquid crystal layer having a refractive-index anisotropy .DELTA.n and a liquid crystal layer thickness d such that the value of a product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the liquid crystal layer thickness d of the liquid crystal is from 350 nm to 700 nm;
• a pair of polarizing plates disposed outside of said first substrate and said second substrate to sandwich the substrates therebetween, a polarizing axis of a first of said polarizing plates being directed toward a direction perpendicular to or parallel to said first direction of the first aligning film of said first substrate, and a polarizing axis of a second of said polarizing plates being directed to cross at substantially a right angle to said first of said polarizing plates;
• a first retardation plate disposed between one of said pair of first and second polarizing plates and said first substrate so that a direction of a delayed phase axis thereof is equal to said first direction of the first aligning film of said first substrate or different from said first direction within a range from -15.degree. to +15.degree., and said first retardation plate having a refractive-index anisotropy .DELTA.n and a thickness d such that the product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the thickness d is from 300 nm to 600 nm;
• and
• a second retardation plate disposed between the other of said pair of first and second polarizing plates and said second substrate so that a direction of a delayed phase axis thereof is substantially perpendicular to the direction of the delayed phase axis of said first retardation plate, and said second retardation plate having a refractive-index anisotropy .DELTA.n and a thickness d such that the product .DELTA.n.multidot.d of the refractive-index anisotropy .DELTA.n and the thickness d is substantially equal to the value of .DELTA.n.multidot.d of said first retardation plate.