Transflective liquid crystal display device having liquid crystal layer with much larger transmissive retardation than reflective retardation
View Patent ↗A liquid crystal display apparatus includes a liquid crystal cell, first and second phase plates and a first polarizing plate stacked, in this order, on the outer surface of a first transparent substrate, third and fourth phase plates and a second polarizing plate stacked, in this order, on the outer surface of a second transparent substrate. The optical characteristics of the liquid crystal cell, the first to fourth phase plates, and the first and second polarizing plates are set within a predetermined range.
1. A liquid crystal display apparatus comprising:
a liquid crystal cell including a liquid crystal layer interposed between a first transparent substrate and a second transparent substrate, wherein a common electrode and a first alignment film are stacked, in this order, on an inner side of the first transparent substrate, a plurality of switching elements and a plurality of pixel electrodes connected to the plurality of switching elements are disposed on an inner side of the second transparent substrate, and a second alignment film is disposed on the switching elements and the pixel electrodes;
a second phase plate, a first phase plate, and a first polarizing plate stacked, in this order, on an outer side of the first transparent substrate; and
a third phase plate, a fourth phase plate, and a second polarizing plate stacked, in this order, on an outer side of the second transparent substrate, wherein:
the liquid crystal cell has a plurality of pixel areas corresponding to the pixel electrodes and the pixel electrodes in predetermined pixel areas are reflective, the predetermined pixel areas being a reflective part configured to reflect incident light from the first transparent substrate and pixel areas other than the predetermined pixel areas being a transmissive part configured to pass light from the second transparent substrate to the first transparent substrate, and
the liquid crystal cell, the first to fourth phase plates, and the first and second polarizing plates having the following optical characteristics:
an axial direction of an absorption axis c of the first polarizing plate is within the range of (ψ+15°)−30° to (ψ+15°)+30°;
retardation (Δnd RF1 ) of the first phase plate is within the range of 250 to 290 nm;
an axial direction of a retardation axis d of the first phase plate is within the range of (ψ+30°)−15° to (ψ+30°)+15°;
retardation (Δnd RF2 ) of the second phase plate is within the range of 160 to 200 nm;
an axial direction of a retardation axis e of the second phase plate is within the range of (ψ+90°)−15° to (ψ+90°)+15°;
retardation (Δnd LT ) of the transmissive part of the liquid crystal cell is within the range of 900 to 1,100 nm;
retardation (Δnd LR ) of the reflective part of the liquid crystal cell is within the range of 115 to 145 nm;
retardation (Δnd RF3 ) of the third phase plate is within the range of 160 to 200 nm;
an axial direction of a retardation axis f of the third phase plate is within the range of (ψ+90°)−15° to (ψ+90°)+15°;
retardation (Δnd RF4 ) of the fourth phase plate is within the range of 250 to 290 nm;
an axial direction of a retardation axis g of the fourth phase plate is within the range of (ψ+150°)−15° to (ψ+150°)+15°; and
an axial direction of an absorption axis h of the second polarizing plate is within the range of (ψ+75°)−30° to (ψ+75°)+30°,
where the axial direction (ψ+N°) (N representing an integer) represents an angle N to an alignment direction ψ of the liquid crystal, (ψ+N°) represents the angle N° to the alignment direction ψ in the counterclockwise direction with respect to the first substrate, and (ψ−N°) represents the angle N° to the alignment direction ψ in the clockwise direction with respect to the first substrate.
2. The liquid crystal display apparatus according to claim 1 , wherein:
the transmissive part operates in a mode in which the alignments of the first and second alignment films in the transmissive part have horizontal alignments and the liquid crystal molecules included the liquid crystal layer are in a bent alignment when a voltage is applied, and
the reflective part operates in a mode in which the one of the first and second alignment films in the reflective part has a perpendicular alignment, the other alignment film has a horizontal alignment, and the liquid crystal molecules included the liquid crystal layer are in a hybrid alignment when a voltage is applied.
3. The liquid crystal display apparatus according to claim 1 , wherein the thickness of the liquid crystal layer in the transmissive part is twice the thickness of the liquid crystal layer in the reflective part.
4. The liquid crystal display apparatus according to claim 1 , wherein the pixel electrodes in the reflective part are reflective pixel electrodes composed of a metal film and the pixel electrodes in the transmissive part are transparent pixel electrodes composed of a transparent conductive film.
5. The liquid crystal display apparatus according to claim 1 , wherein a color filter is interposed between the first transparent substrate and the common electrode, and the color filter in the reflective part is thinner than the color filter in the transmissive part.
6. The liquid crystal display apparatus according to claim 1 , wherein a color filter is interposed between the first transparent substrate and the common electrode, a transparent resin film is stacked on the color filter on the side facing the liquid crystal layer in the reflective part, and the total thickness of the color filter and the transparent resin layer in the reflective part is the same as the thickness of the color filter in the transmissive part.
7. The liquid crystal display apparatus according to claim 4 , wherein a sidewall of the reflective part is formed adjacent to a periphery of the transmissive part and an angle of inclination of the sidewall is within the range of 25° to 55°.