Liquid crystal display with switching transistor for each pixel

• US 4,710,768 A
• Filed: 10/11/1984
• Issued: 12/01/1987
• Est. Priority Date: 10/13/1983
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Takeda, Makoto, Yamamoto, Kunihiko, Nonomura, Keisaku
• Primary Examiner(s): Curtis, Marshall M.
• Application Number:
  US06/660,005
• Time in Patent Office: 1,146 Days
• Field of Search: 340/784, 340/805, 340/718, 340/719, 340/792, 350/330, 350/333
• US Class Current: 345/90
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: H04N 3/127 using liquid crystals

Abstract

A liquid crystal display device comprising display picture element electrodes connected to switching transistors formed at each crossing of the row and column electrodes of a matrix array with the opposite electrodes being opposite from the display picture element electrodes and across from the interfacing liquid crystal layer. Video signals are inverted into alternating positive/negative polarities for every field and applied to the column electrodes. A specific voltage that inverts its polarity in the same timing as the video signals is applied to the opposite electrodes. The drive method thus embodied by the present invention effectively minimizes the power consumption and allows for compensation of uneven display contrast effects.

Claims

1. A liquid crystal display device comprising:

a liquid crystal display including,

row and column electrodes formed as a matrix array on a first substrate,

a switching transistor formed at the intersection of each said row and column electrode,

a display picture element electrode connected to each said switching transistor defining a display element,

an opposed electrode formed on a second substrate at a position opposite from each said display picture element electrode, and

a liquid crystal layer disposed between said display picture element electrodes and said opposed electrodes; and

signal processing means connected to said liquid crystal display for providing a video signal, having fields of alternating positive/negative polarity to said column electrodes and for sequentially applying scan pulses to said row electrodes; and

opposed electrode signal generator means for applying an alternating predetermined voltage in synchronism with the fields of alternating polarity of said video signal but of opposite voltage polarity thereto to said opposed electrodes to produce a sum voltage of said video signal and said alternating predetermined voltage across each said display element, said sum voltage applied to each said display element having a voltage greater than either said video signal supplied to that said display element or said alternating predetermined voltage.

2. A liquid crystal display device according to claim 1 wherein said opposed electrode signal generator means includes means for providing a specific rectangular waveform to said opposed electrodes so that when said video signal is not being provided to said column electrodes, a threshold voltage can be applied to said liquid crystal layer of each said display element.

3. A liquid crystal display device according to claim 1 wherein said opposed electrode signal generator means includes means for providing a specific voltage waveform to said opposed electrodes, in which said specific voltage waveform is varied to compensate for an unevenness of display contrast in the liquid crystal layer parallel to said column electrodes to render display contrast in the direction of said column electrodes even.