Retardation plate, method for manufacturing the retardation plate, and liquid crystal display

A liquid crystal display comprising:

• first and second substrates facing each other;
• a liquid crystal layer interposed between the first and second substrates;
• a solidified liquid crystal layer supported by a main surface of the first substrate facing the second substrate, having biaxial optical anisotropy, and comprising first to third regions, the first to third regions being arranged on the substrate, an in-plane retardation of the solidified liquid crystal layer being the smallest in the first region and the greatest in the third region, an Nz coefficient of the solidified liquid crystal layer being the greatest in the first region and the smallest in the third region, and the solidified liquid crystal layer being formed as a continuous film composed of a same material;
• and
• a color filter layer supported by the first or second substrate between the first and second substrates and comprising first to third coloring layers, the first to third coloring layers having different absorption spectra and facing the first to third regions, respectively.

A method for manufacturing a retardation plate, comprising forming a solidified liquid crystal layer on a substrate, the formation of the solidified liquid crystal layer comprising:

• a step of forming a liquid crystal material layer on the substrate, the liquid crystal material layer comprising a photo-polymerizing or photo-crosslinking thermotropic liquid crystal compound, a chiral agent, and a dichroic photo-polymerization initiator, and mesogens of the thermotropic liquid crystal compound forming a cholesteric alignment structure;
• a step of irradiating at least two regions of the liquid crystal material layer with different exposure values of linearly polarized light and different exposure values of unpolarized parallel light, thereby polymerizing or crosslinking at least a portion of the thermotropic liquid crystal compound with different proportions and different degrees of anisotropy to generate a polymerized or crosslinked product;
• a subsequent step of heating the liquid crystal material layer to a temperature equal to or higher than a phase transition temperature at which the thermotropic liquid crystal compound changes from a liquid crystal phase to an isotropic phase, thereby changing an orientation state of the mesogens of the unreacted thermotropic liquid crystal compound in the at least two regions;
• and
• a step of polymerizing and/or crosslinking the unreacted compound with the orientation state of the mesogens maintained.

A method for manufacturing a retardation plate, comprising forming a solidified liquid crystal layer on a substrate, the formation of the solidified liquid crystal layer comprising:

• a step of forming a liquid crystal material layer on the substrate, the liquid crystal material layer comprising a photo-polymerizing or photo-crosslinking thermotropic liquid crystal compound, a chiral agent, and a dichroic photo-polymerization initiator, and mesogens of the thermotropic liquid crystal compound forming a cholesteric alignment structure;
• a step of irradiating at least two regions of the liquid crystal material layer with elliptically polarized light having different ellipticities, thereby polymerizing or crosslinking at least a portion of the thermotropic liquid crystal compound with different proportions and different degrees of anisotropy to generate a polymerized or crosslinked product;
• a subsequent step of heating the liquid crystal material layer to a temperature equal to or higher than a phase transition temperature at which the thermotropic liquid crystal compound changes from a liquid crystal phase to an isotropic phase, thereby changing an orientation state of the mesogens of the unreacted thermotropic liquid crystal compound in the at least two regions;
• and
• a step of polymerizing and/or crosslinking the unreacted compound with the orientation state of the mesogens maintained.

A retardation plate comprising:

• a substrate;
• and
• a solidified liquid crystal layer which is a continuous film made of a same material supported by the substrate, and has biaxial optical anisotropy, the solidified liquid crystal layer comprising a plurality of regions, the plurality of regions being arranged on the substrate and being different in in-plane birefringence and thickness direction birefringence,
• a number of the regions in the solidified liquid crystal layer being 3 or more, and
• the in-plane birefringence of the solidified liquid crystal layer being the smallest in the first region and the greatest in the third region, and the Nz coefficient of the solidified liquid crystal layer being the greatest in the first region and the smallest in the third region;
• a color filter layer which is interposed between the substrate and the solidified liquid crystal layer, or faces the substrate with the solidified liquid crystal layer interposed therebetween, the color filter layer comprising first to third coloring layers having different absorption spectra and facing the first to third regions, respectively,
• a wavelength of light transmissible through the color filter layer being the shortest in the first coloring layer, and the longest in the third coloring layer.