Liquid crystal display apparatus

• US 6,670,937 B1
• Filed: 02/29/2000
• Issued: 12/30/2003
• Est. Priority Date: 03/01/1999
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Tsuboyama, Akira, Sato, Koichi, Hanyu, Yukio
• Primary Examiner(s): Saras, Steven
• Assistant Examiner(s): Kumar, Srilakshmi K.
• Application Number:
  US09/515,609
• Time in Patent Office: 1,400 Days
• Field of Search: 345/94-101, 345/87, 345/89, 359/63
• US Class Current: 345/97
• CPC Class Codes: G09G 2320/0204 Compensation of DC component across the pixels in flat panels
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals

Abstract

A liquid crystal display apparatus is constituted by a liquid crystal device comprising a pair of substrates each having thereon an electrode and a liquid crystal disposed between the pair of substrates and providing a tilt angle, driving voltage application means for applying a driving voltage to the liquid crystal, and at least one polarizer having a polarizing axis. The liquid crystal has a voltage-dependent alignment characteristic such that the tilt angle continuously changes depending on the driving voltage applied to the liquid crystal, and the above at least one polarizer is disposed so that the polarizing axis is shifted from positions providing a maximum transmittance and minimum transmittance under application of no electric field to increase the resultant transmittance and contrast.

Claims

1. A liquid crystal display apparatus, comprising:

a liquid crystal device comprising a pair of substrates each having thereon an electrode and a liquid crystal disposed between the pair of substrates and providing a tilt angle,

driving voltage application means for applying a driving voltage to the liquid crystal, and

a pair of polarizers, each of said pair having a polarizing axis, wherein

said liquid crystal has a voltage-dependent alignment characteristic such that the tilt angle continuously changes depending on the driving voltage applied to the liquid crystal, and

both of said pair of polarizers are disposed so that each polarizing axis is shifted from a position in alignment with an optical axis of the liquid crystal under application of no electric field.

2. An apparatus according to claim 1, wherein the liquid crystal provides a maximum tilt angle max of at least 22.5 degrees and said at least one polarizer is disposed so that the polarizing axis is placed in a position providing a minimum transmittance when the liquid crystal is supplied with a voltage for providing the liquid crystal with a tilt angle of substantially 45 degrees minus max (degrees).

3. An apparatus according to claim 1, wherein the driving voltage application means applies a non-zero voltage to the liquid crystal so that the liquid crystal has an optical axis providing a darkest state based on gradation data providing a minimum transmittance.

4. An apparatus according to claim 3, which further comprises a temperature-detecting device for detecting a temperature of the liquid crystal device and temperature-compensating means for changing the driving voltage depending on the detected temperature.

5. An apparatus according to claim 1, wherein the driving voltage application means applies to the liquid crystal the driving voltage and a voltage identical in absolute value to but opposite in polarity to the driving voltage in one frame period.

6. An apparatus according to claim 5, further including a backlight which is turned on during a display period after the driving voltage is applied and is turned off in said one frame period other than the display period.

7. A liquid crystal display apparatus, comprising:

a liquid crystal device comprising a pair of substrates each having thereon an electrode and a liquid crystal disposed between the pair of substrates and providing a tilt angle,

driving voltage application means for applying a driving voltage to the liquid crystal, and

a pair of polarizers, each of said pair having a polarizing axis, wherein

said liquid crystal has a voltage-dependent alignment characteristic such that the tilt angle continuously changes depending on the driving voltage applied to the liquid crystal, and

both of said pair of polarizers are disposed so that each polarizing axis is shifted from a position providing a minimum transmittance under application of no electric field.

8. A liquid crystal display apparatus, comprising:

a liquid crystal device comprising a pair of electrodes and a liquid crystal disposed between the pair of electrodes and providing a tilt angle,

driving voltage application means for applying a driving voltage to the liquid crystal, and

a pair of polarizers, each of said pair having a polarizing axis, wherein

said liquid crystal has a voltage dependent alignment characteristic such that the tilt angle continuously changes depending on the driving voltage applied to the liquid crystal, and wherein each of said pair of polarizers is disposed so that its polarizing axis is shifted from a position in alignment with an optical axis of the liquid crystal in the absence of an electric field.