Liquid crystal display unit with a plurality of subpixels

• US 5,748,276 A
• Filed: 12/09/1996
• Issued: 05/05/1998
• Est. Priority Date: 05/31/1994
• Status: Expired due to Fees

• Current Assignee: Toshiba Matsushita Display Technology (Japan Display Incorporated)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Asada, Satoshi, Uno, Mitsuhiro, Takada, Naomi, Kumagawa, Katsuhiko, Takubo, Yoneharu
• Primary Examiner(s): Sikes, William L.
• Assistant Examiner(s): Duong, Tai V.
• Application Number:
  US08/762,419
• Time in Patent Office: 512 Days
• Field of Search: 349/85, 349/110, 349/144, 349/143, 349/42, 349/43, 349/38, 345/87, 345/89, 345/92, 345/152, 345/147
• US Class Current: 349/144
• CPC Class Codes: G02F 1/133512 Light shielding layers, e.g. black matrix G02F1/136209 takes precedence
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: G02F 1/134354 the sub-pixels being capacitively coupled
• CPC Class Codes: G02F 1/136213 Storage capacitors associated with the pixel electrode

Abstract

A liquid crystal display unit including a plurality of subpixels in each pixel provides superior gradation over a wide viewing angle, and is produced with no increase in manufacturing cost and no deterioration of desired properties (such as reduction in brightness, contrast and response). No additional manufacturing step is required since a control capacitor electrode is formed at the same time as source and drain electrodes constituting a thin-film transistor. By controlling the ratio of display area and the difference in applied voltage of the subpixels, preferable viewing angle properties are obtained. The display properties at the boundary of subpixels are improved by controlling the gap width and the direction of boundary of the subpixels, thus providing a bright display.

Claims

1. A liquid crystal display unit comprising:

two insulating substrates;

a liquid crystal layer sandwiched between said two insulating substrates;

a plurality of pixels arranged in a matrix;

at least two subpixels in each pixel; and

means for applying voltage to a liquid crystal layer of each subpixel;

wherein voltage applied to a liquid crystal layer of one subpixel is different from voltage applied to a liquid crystal layer of another subpixel; and

wherein a ratio of display area between said subpixels and a difference in driving voltage of said subpixels are controlled so that the correlation between quantity of light and signaling voltage is monotonously falling or monotonously rising;

said pixel being observed at an angle of 0°

-40°

inclined from an axis perpendicular to said insulating substrates along a long axis of liquid crystal molecules positioned in a middle layer of said liquid crystal layer with no application of voltage.

2. The liquid crystal display unit of claim 1, wherein the pixel comprises two subpixels.

3. The liquid crystal display unit of claim 2, wherein the two subpixels have different driving voltages;

wherein a difference in driving voltages (Δ

V) being expressed as follows;

space="preserve" listing-type="equation">-0.2V<

-Δ

V<

0.8V;

space="preserve" listing-type="equation">γ

=|V10-V 90|;

and

space="preserve" listing-type="equation">Δ

V=|V50'"'"'-V50|;

where V10, V50 and V90 are signaling voltages so as to set quantities of light for one subpixel, which is driven applying high voltage, at 90%, 50% and 10% relative to a maximum quantity of light, and V50'"'"' is a signaling voltage so as to set a quantity of light of another subpixel, which is driven applying low voltage, at 50% relative to a maximum quantity of light.

4. The liquid crystal display unit of claim 3, wherein the two subpixels have from 8:

2 to 6;

4 ratios of display areas;

said ratios of display areas being ratios of a display area of one of said subpixels relative to a display area of another subpixel.

5. A liquid crystal display unit comprising:

two insulating substrates;

a liquid crystal layer sandwiched between said two insulating substrates;

a polarizing plate on an exterior surface of each insulating substrate so as to set a polarizing axis of one polarizing plate at right angles to a polarizing axis of another polarizing plate;

a plurality of pixels arranged in a matrix;

at least two subpixels in each pixel; and

means for controlling voltage applied to each subpixel;

wherein voltage applied to one subpixel is different from voltage applied to another subpixel; and

wherein 0°

≦

φ

≦

450°

where (is an angle between a long axis of liquid crystal molecules when viewed from a direction perpendicular to said two insulating substrates and a boundary between said subpixels with no application of voltage.

6. The liquid crystal display unit of claim 5, further comprising a thin-film transistor and a control capacitor on one of the insulating substrates.