Liquid crystal device and driving method therefor

• US 6,693,695 B2
• Filed: 01/14/2003
• Issued: 02/17/2004
• Est. Priority Date: 06/18/1998
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Watanabe, Yasuyuki, Munakata, Hirohide, Tsuboyama, Akira, Asao, Yasufumi, Okada, Shinjiro
• Primary Examiner(s): Ton, Toan
• Application Number:
  US10/341,443
• Publication Number:
  US 20030133065A1
• Time in Patent Office: 399 Days
• Field of Search: 349/129, 349/130, 349/134, 349/33, 349/187, 349/179
• US Class Current: 349/130
• CPC Class Codes: G02F 1/133738 for homogeneous alignment
• CPC Class Codes: G02F 1/133742 for homeotropic alignment
• CPC Class Codes: G02F 1/133753 with different alignment orientations or pretilt angles on a same surface, e.g. for grey scale or improved viewing angle
• CPC Class Codes: G02F 1/13787 Hybrid-alignment cells G02F1/1393 takes precedence
• CPC Class Codes: G02F 1/1395 Optically compensated birefringence [OCB]- cells or PI- cells
• CPC Class Codes: G02F 1/1397 the twist being substantially higher than 90°, e.g. STN-, SBE-, OMI-LC cells

Abstract

At least one of a pair of substrates constituting a liquid crystal device is provided with a composite alignment film including a homeotropic alignment film region and a homogeneous alignment film region, whereby the liquid crystal in contact with the homogeneous alignment film region is surrounded by the region of liquid crystal in a hybrid or homeotropic alignment state and is stably held in a twit alignment state under no electric field which can be continuously transformed into a bend alignment state. As a result, it is possible to provide a liquid crystal device capable of display by utilizing bend alignment with reduced bending voltage and voltage for holding the bend alignment.

Claims

1. A driving method for a liquid crystal device of the type comprising:

a pair of substrates one of which is provided with a thin film transistor, and a nematic liquid crystal disposed between the substrates, wherein the liquid crystal is initially aligned in splay alignment, converted into bend alignment under application of a prescribed voltage, and changed into twist state when the prescribed voltage is removed, said driving method comprising;

applying a data signal voltage at the time of picture display to the liquid crystal via the thin film transistor so that an absolute value of the data signal voltage is at least a voltage for transforming an alignment state of the liquid crystal from twist alignment to bend alignment.

2. A driving method according to claim 1, wherein the data signal voltage is at most the prescribed voltage.