Display device

• US 5,627,560 A
• Filed: 06/06/1995
• Issued: 05/06/1997
• Est. Priority Date: 06/09/1994
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Verhulst, Antonius G. H.
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US08/470,893
• Time in Patent Office: 700 Days
• Field of Search: 345/92, 345/90, 345/89, 345/87, 345/94, 345/97, 345/95, 345/96, 345/99, 345/98, 345/100, 345/103, 345/208, 345/209, 345/210, 359/55, 359/56, 348/790, 348/791, 348/792, 348/793
• US Class Current: 345/97
• CPC Class Codes: G09G 2310/0227 related to multiple interlacing, i.e. involving more fields than just one odd field and one even field
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0209 Crosstalk reduction, i.e. to reduce direct or indirect influences of signals directed to a certain pixel of the displayed image on other pixels of said image, inclusive of influences affecting pixels in different frames or fields or sub-images which constitute a same image, e.g. left and right images of a stereoscopic display
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• CPC Class Codes: G09G 3/3651 using multistable liquid crystals, e.g. ferroelectric liquid crystals
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

In a ferro-electric liquid crystal display, in which the pixels in one row first receive a reset or "blanking" signal, this reset signal is presented by providing the counter electrode, prior to selection, with a reset voltage while simultaneously selecting the row of pixels to be reset. When a single counter electrode is used, it switches to a reset voltage during each selection period. If the counter electrode is divided into sub-strips, these strips switch to a reset voltage once per picture period.

Claims

1. A display device comprising a first substrate having a group of selection electrodes and a group of data electrodes and a matrix of picture electrodes arranged in rows and columns at the locations of ferro-electric liquid crystal display elements between the first substrate and a second substrate provided with a counter electrode, each display element being connected to a data electrode via an active switching element and the display device comprising means for bringing, prior to selection, a row of display elements to an extreme optical transmission state by means of an auxiliary signal, characterized in that the display device comprises a drive circuit for alternately applying the auxiliary signal and a data-offset voltage (V_comsel) to the counter electrode on the second substrate, said data-offset voltage being applied to said counter electrode during the application of a data voltage to one of said data electrodes.

3. A display device as claimed in claim 1 or 2, characterized in that the drive circuit comprises means for presenting the auxiliary signal to a first row of display elements during a part of a line period and for presenting the data-offset voltage to a second row of display elements during at least a portion of the other part of the line period.

4. A display device as claimed in claim 1 or 2, characterized in that the drive circuit comprises means for presenting the auxiliary signal to a first row of display elements during a part of a line period and for presenting the data-offset voltage to the same row of display elements during at least a portion of the other part of the line period.

2. A display device comprising a first substrate having a group of selection electrodes and a group of data electrodes and a matrix of ferro-electro-optical display elements arranged in rows and columns between the first and a second substrate, each having a picture electrode on the first substrate, which picture electrode is connected to a data electrode via an active switching element, the display device comprising means for bringing, prior to selection, a row of display elements to an extreme optical transmission state by means of an auxiliary signal, characterized in that the second substrate is provided with electrode strips extending in the row direction which, together with rows of picture electrodes located opposite the electrode strips and intermediate ferro-electric liquid crystal material form part of rows of display elements, the display device comprising a drive circuit for alternately applying the auxiliary signal and a data-offset voltage (V_comsel) to the electrode strips, said data-offset voltage being applied to one of said electrode strips during the application of a data voltage to one of said data electrodes.