Active matrix liquid crystal display panel

• US 6,842,207 B2
• Filed: 10/29/1997
• Issued: 01/11/2005
• Est. Priority Date: 10/29/1996
• Status: Expired due to Term

• Current Assignee: NLT Technologies, Ltd. (Tianma Microelectronics Company Limited)
• Original Assignee: NEC Corporation, NEC LCD Technologies Limited (Tianma Microelectronics Company Limited)
• Inventors: Hirai, Yoshihiko, Fujimaki, Eriko, Watanabe, Makoto, Nishida, Shinichi, Suzuki, Teruaki, Suzuki, Masayoshi
• Primary Examiner(s): Chowdhury, Tarifur R.
• Assistant Examiner(s): QI, ZHI QIANG
• Application Number:
  US08/960,224
• Publication Number:
  US 20020030780A1
• Time in Patent Office: 2,631 Days
• Field of Search: 349/107, 349/141, 349/117, 349/75, 349/121, 349/54, 349/120, 349/106
• US Class Current: 349/107
• CPC Class Codes: G02F 1/133371 Cells with varying thickness of the liquid crystal layer
• CPC Class Codes: G02F 1/13363 Birefringent elements, e.g. for optical compensation
• CPC Class Codes: G02F 1/133632 with refractive index ellipsoid inclined relative to the LC-layer surface
• CPC Class Codes: G02F 1/134363 for applying an electric field parallel to the substrate, i.e. in-plane switching [IPS]
• CPC Class Codes: G02F 2413/02 Number of plates being 2
• CPC Class Codes: G02F 2413/10 with refractive index ellipsoid inclined, or tilted, relative to the LC-layer surface O plate
• CPC Class Codes: G02F 2413/105 with varying inclination in thickness direction, e.g. hybrid oriented discotic LC

Abstract

An active matrix liquid crystal display panel by which a good display characteristic can be obtained without suffering from gradation reversal over a wide visibility angle range. A liquid crystal layer 4 is formed such that the thickness thereof varies in accordance with transmission wavelengths of color layers 6, 7 and 8 so that a very good display which does not exhibit any coloring in whichever direction it is viewed may be obtained.

An active matrix substrate A includes a plurality of opposing electrodes 2, a plurality of pixel electrodes 3 parallel to the opposing electrodes 2, a thin film transistor, and an orientation film 23 all formed on a glass substrate 10. A color filter substrate C includes an orientation film 56 provided on one surface of another glass substrate 10 and an optical compensation layer 35 provided on the other surface of the glass substrate 10 and formed from a plastic film. The two substrates are disposed such that the orientation films thereof oppose each other, and polarization plates 34 and 5 are disposed on the outer sides of the two substrates, and a liquid crystal layer 4 having a positive refractive index anisotropy is provided between the orientation films 23. The optical compensation layer 35 has a negative one axial refractive index anisotropy and can cancel a retardation produced in the liquid crystal layer 4 thereby to suppress white floating of a black display portion.

Claims

1. An active matrix liquid crystal display panel, comprising:

a first substrate on which a plurality of color layers having transmission wavelengths different from each other are provided in parallel to each other;

a second substrate disposed in an opposing relationship to said first substrate with a predetermined clearance left from said first substrate for generating a predetermined electric field when a predetermined voltage is applied; and

a liquid crystal layer formed from liquid crystal injected in a gap defined by a surface of said first substrate adjacent said second substrate and a surface of said second substrate adjacent said first substrate;

the electric field generated by said second substrate being substantially parallel to said liquid crystal layer to control a display;

said liquid crystal layer having a thickness which varies depending upon the transmission wavelengths of said color layers, whereby coloring is controlled in a case of an oblique view with respect to said first substrate and said second substrate,

wherein said second substrate comprises;

a plurality of pixel electrodes provided corresponding to said color layers, the predetermined voltage being applied to said pixel electrodes; and

a plurality of opposing electrodes provided in parallel to said pixel electrodes for each of said color layers for cooperating, when the voltage is applied to said pixel electrodes, with said pixel electrodes to generate the electric field therebetween,

whereby maximum brightness for each R,G,B is gained by applying different driving voltages to the pixel electrodes, depending upon the thickness of the crystal layers in each of the color layers, wherein larger voltage is applied to each of the pixel electrodes for the color layers with thinner liquid crystal layer to get maximum brightness for each color.

2. An active matrix liquid crystal display panel as claimed in claim 1, wherein said liquid crystal layer has a thickness which increases in proportion to one wavelength selected from a wavelength region in which transmission factors of said color layers are higher than 70% those at peaks of transmission spectra of said color layers.

3. An active matrix liquid crystal display panel, comprising:

a first substrate on which a plurality of color layers having transmission wavelengths different from each other are provided in parallel to each other;

a second substrate disposed in an opposing relationship to said first substrate with a predetermined clearance left from said first substrate for generating a predetermined electric field when a predetermined voltage is applied; and

a liquid crystal layer formed from liquid crystal injected in a gap defined by a surface of said first substrate adjacent said second substrate and a surface of said second substrate adjacent said first substrate;

the electric field generated by said second substrate being substantially parallel to said liquid crystal layer to control a display;

said liquid crystal layer having a thickness which varies depending upon the transmission wavelengths of said color layers,

wherein said second substrate includes

a plurality of pixel electrodes provided corresponding to said color layers, the predetermined voltage being applied to said pixel electrodes, and

a plurality of opposing electrodes provided in parallel to said pixel electrodes for each of said color layers for cooperating, when the voltage is applied to said pixel electrodes, with said pixel electrodes to generate the electric field therebetween,

said pixel electrodes and said opposing electrodes being spaced from each other by distances which are different for the individual color layers.

4. An active matrix liquid crystal display panel as claimed in claim 3, wherein said first substrate has a protective layer provided on a surface thereof adjacent said second substrate for preventing elusion of impurities from said color layers.