Liquid crystal display device having improved electrodes for a multi-tone image

• US 4,850,677 A
• Filed: 03/18/1988
• Issued: 07/25/1989
• Est. Priority Date: 03/18/1987
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Okumura, Fujio
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Pellman, Anita E.
• Application Number:
  US07/169,811
• Time in Patent Office: 494 Days
• Field of Search: 350/333, 350/336, 340/784
• US Class Current: 349/144
• CPC Class Codes: G02F 1/134336 Matrix
• CPC Class Codes: G02F 1/134345 Subdivided pixels, e.g. for grey scale or redundancy
• CPC Class Codes: H04N 3/127 using liquid crystals

Abstract

The disclosed liquid crystal display device is composed of a transparent substrate and a plurality of pixels formed on the substrate, each pixel having a vertical electrode, a plurality of horizontal electrodes and liquid crystal interposed between the vertical and horizontal electrodes, and the horizontal electrodes in each pixel having different areas from each other. Ferroelectric liquid crystal is favorably used for the interposed liquid crystal.

Claims

1. A liquid crystal display device comprising:

a first transparent substrate having an upper surface;

a first electrode formed on said upper surface of said first transparent substrate;

a second transparent substrate having a bottom surface;

a set of second electrodes formed on said bottom surface of said second transparent substrate in parallel with each other to face said first electrode, said set of second electrodes composing of N-electrodes having different widths, wherein N is an integer of plural number;

a liquid crystal interposed between said first and second transparent substrate through said first and second electrodes;

an analog-digital converter converting an analog input signal to a digital signal having bits corresponding to said N, said digital signal of said bits having a combination of first and second constant voltages presenting an analog value of said analog input signal; and

a means connected to said analog-digital converter for applying said digital signal between said first electrode and said set of said second electrodes at a time to display a figure by changing orientation of said liquid crystal.

2. A liquid crystal display device as claimed in claim 1, wherein said first electrode and said set of second electrodes form a pixel, said display device having a plurality of pixels arranged in a matrix form, and said matrix being formed by a plurality of said first electrodes arranged on said upper surface of said first transparent substrate elongated and in parallel with each other and a plurality of sets of said second electrodes arranged on said bottom surface of said second transparent substrate elongated and in parallel with each other so as to cross said plurality of first electrodes.

3. A liquid crystal display device as claimed in claim 2, wherein said second electrodes in each of said sets have widths of about 1/2, 1/2² . . . , 1/2^N of a width of said each of said respective sets of said second electrodes.

4. A liquid crystal display device as claimed in claim 3, wherein said liquid crystal is a ferroelectric liquid crystal.

5. A liquid crystal display device comprising:

a transparent support substrate having an upper surface;

a plurality of vertical electrodes arranged on said upper surface of said support substrate elongated and in parallel with each other;

a transparent cover substrate having a bottom surface;

a plurality of sets of horizontal electrodes arranged on said bottom surface of said cover substrate elongated and in parallel with each other so as to cross said vertical electrodes, each of said sets composing of N-horizontal electrodes having different widths, wherein N is an integer of plural number;

a lower orientation film covering said upper surface of said support substrate and said vertical electrodes;

an upper orientation film covering said bottom surface of said cover substrate and said horizontal electrodes;

a liquid crystal interposed between said lower and upper orientation film;

an analog-to-digital converter converting an analog input signal to a digital signal having bits corresponding to said N, said digital signal of said bits having a combination of first and second constant voltages presenting an analog value of said analog input signal; and

means connected to said analog-digital converter for applying said digital signal between one of said vertical electrodes and one of said sets of horizontal electrodes at a time to display a figure by changing orientation of said liquid crystal.

6. A liquid crystal display device as claimed in claim 5, wherein said liquid crystal is a ferroelectric liquid crystal.

7. A liquid crystal display device as claimed in claim 6, wherein each of said sets of horizontal electrodes has a first width in a direction along said vertical electrodes, respectively, and said horizontal electrodes in each set have second widths which are about 1/2, 1/4, . . . , 1/2^N of said first width.