EP0666555B1 - Ansteuerungsverfahren für DHF-LCD - Google Patents

Ansteuerungsverfahren für DHF-LCD Download PDF

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Publication number
EP0666555B1
EP0666555B1 EP95100351A EP95100351A EP0666555B1 EP 0666555 B1 EP0666555 B1 EP 0666555B1 EP 95100351 A EP95100351 A EP 95100351A EP 95100351 A EP95100351 A EP 95100351A EP 0666555 B1 EP0666555 B1 EP 0666555B1
Authority
EP
European Patent Office
Prior art keywords
voltage
dhf
triggering method
pulses
maximum
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP95100351A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0666555A1 (de
Inventor
Jürg FÜNFSCHILLING
Martin Schadt
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rolic Technologies Ltd
Original Assignee
Rolic AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Rolic AG filed Critical Rolic AG
Publication of EP0666555A1 publication Critical patent/EP0666555A1/de
Application granted granted Critical
Publication of EP0666555B1 publication Critical patent/EP0666555B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/04—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions
    • G09G3/16—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions by control of light from an independent source
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3622—Control of matrices with row and column drivers using a passive matrix
    • G09G3/3629—Control of matrices with row and column drivers using a passive matrix using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers
    • G09G3/3648—Control of matrices with row and column drivers using an active matrix
    • G09G3/3651—Control of matrices with row and column drivers using an active matrix using multistable liquid crystals, e.g. ferroelectric liquid crystals
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0243—Details of the generation of driving signals
    • G09G2310/0251—Precharge or discharge of pixel before applying new pixel voltage
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2011—Display of intermediate tones by amplitude modulation

Definitions

  • the invention relates to a control method for the pixels one DHF type liquid crystal cell (DHF-LCD).
  • DHF LCDs are in the European patent EP 0 309 774 B1.
  • Liquid crystal cells of the DHF type can be operated in two different modes: In the asymmetrical mode, the cell is arranged between crossed polarizers in such a way that the transmission is minimal for a certain, eg negative voltage-U 0 and maximum for + U 0 . In symmetrical mode, the cell is arranged so that the transmission is minimal for 0 V applied voltage and increases for positive and negative voltages.
  • the cell In asymmetric mode, the cell is more sensitive, i.e. of the electro-optical effect is around twice as large as in the symmetrical Mode. There is a risk that in the event of not being free of DC voltage Triggering electrochemical processes or Polarization charges in the orientation layers of the Liquid crystal cell are generated. Both effects can be phantom images to lead. In symmetrical mode this can be avoided by alternating a picture with positive tension and with drives negative voltage.
  • each pixel are semiconductor elements (transistors or Diodes) assigned, which enable the display to be multiplexed.
  • the invention has for its object a control to indicate with the lowest possible voltage in combination with an active matrix achieves the shortest possible switching time of DHF-LCDs becomes.
  • the static capacitance C s is the capacitance at which the director does not move.
  • C hx describes the fact that the deformation of the ferroelectric helix is associated with a charge (polarization charge).
  • R hx describes the associated friction losses.
  • C hx is several times larger than C s .
  • the charging of C s is fast and only limited by the output impedance of the voltage source used.
  • a DHF cell is activated with an active matrix, a low-impedance signal is present at the pixel during the row addressing time t z (typically 64 ⁇ sec). Then the pixel is isolated until the next image (typically 40 ms). During this time, the charge that has flowed to the pixel in the row addressing time is distributed among the two capacitors so that they are charged to the same voltage. If the resulting charge on C hx is large enough to cause the desired deformation, there are no problems.
  • the pre-pulses shown in FIG. 2 below during the time segment 2 unload the pixel so that the data pulses during period 3 only still need to charge to the new grayscale value.
  • the pre-pulses shown in FIG. 3 below during the time segment 2 preload the pixel to a suitable value.
  • the data pulses then less charge must be added or during the time period 3 dissipate.
  • the data pulses have the same polarity as the precharge pulses.
  • the pre-pulses shown in the middle and below in FIG. 4 during the time segment 2 charge the pixel to the maximum voltage.
  • the data pulses during the time period 3 then discharge the pixel to the desired gray value.
  • This can be done in two ways: either (1) by amplitude modulation as in FIGS. 2 and 3, ie by pulses of different amplitudes (center of FIG. 4), the full voltage swing of -U 0 ... U 0 can be used, or (2) by pulse width modulation, ie by pulses of maximum voltage U 0 but different pulse lengths (Fig. 4 below). With this type of control, the polarity does not have to change depending on the gray level as with amplitude modulation.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Liquid Crystal (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
EP95100351A 1994-01-26 1995-01-12 Ansteuerungsverfahren für DHF-LCD Expired - Lifetime EP0666555B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH23394 1994-01-26
CH233/94 1994-01-26

Publications (2)

Publication Number Publication Date
EP0666555A1 EP0666555A1 (de) 1995-08-09
EP0666555B1 true EP0666555B1 (de) 1998-07-08

Family

ID=4182326

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95100351A Expired - Lifetime EP0666555B1 (de) 1994-01-26 1995-01-12 Ansteuerungsverfahren für DHF-LCD

Country Status (8)

Country Link
US (1) US6163311A (ja)
EP (1) EP0666555B1 (ja)
JP (1) JP3520122B2 (ja)
KR (1) KR100254648B1 (ja)
CN (1) CN1096051C (ja)
DE (1) DE59502715D1 (ja)
HK (1) HK1011445A1 (ja)
SG (1) SG47897A1 (ja)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11242207A (ja) * 1997-12-26 1999-09-07 Sony Corp 電圧発生回路、光学空間変調素子、画像表示装置並びに画素の駆動方法
KR20000001145A (ko) * 1998-06-09 2000-01-15 손욱 반강유전성 액정표시장치의 구동방법
WO2005062287A1 (ja) * 2003-12-24 2005-07-07 Hiji High-Tech Co., Ltd. 表示パネルの信号線駆動装置

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4701026A (en) * 1984-06-11 1987-10-20 Seiko Epson Kabushiki Kaisha Method and circuits for driving a liquid crystal display device
DE3876059D1 (de) * 1987-09-18 1992-12-24 Hoffmann La Roche Ferroelektrische fluessigkristallzelle.
DE58908399D1 (de) * 1988-08-12 1994-10-27 Hoffmann La Roche Verfahren und Vorrichtung zur beschleunigten Ansteuerung von Flüssigkristallzellen des DHF-Typs.
DE3919839A1 (de) * 1989-06-17 1990-12-20 Hoechst Ag Fluessigkristall-schalt- und anzeige-element
US5243455A (en) * 1990-05-11 1993-09-07 The University Of Colorado Foundation, Inc. Chiral smectic liquid crystal polarization interference filters
US5073010A (en) * 1990-05-11 1991-12-17 University Of Colorado Foundation, Inc. Optically addressable spatial light modulator having a distorted helix ferroelectric liquid crystal member
US5539555A (en) * 1990-07-20 1996-07-23 Displaytech, Inc. High contrast distorted helex effect electro-optic devices and tight ferroelectric pitch ferroelectric liquid crystal compositions useful therein
GB2247972B (en) * 1990-09-11 1994-07-27 Stc Plc Co-ordinate addressing of liquid crystal cells
US5172257A (en) * 1991-11-08 1992-12-15 Bell Communications Research, Inc. Twisted ferroelectric liquid crystal modulator for providing gray scale
US5493426A (en) * 1991-11-14 1996-02-20 University Of Colorado Foundation, Inc. Lateral electrode smectic liquid crystal devices
US5552912A (en) * 1991-11-14 1996-09-03 Board Of Regents Of The University Of Colorado Chiral smectic liquid crystal optical modulators
US5490000A (en) * 1992-12-07 1996-02-06 Casio Computer Co., Ltd. Deformed helix ferroelectric liquid crystal display device and method of driving
JPH06194625A (ja) * 1992-12-24 1994-07-15 Casio Comput Co Ltd 強誘電性液晶表示素子の駆動方法
US5631752A (en) * 1992-12-24 1997-05-20 Casio Computer Co., Ltd. Antiferroelectric liquid crystal display element exhibiting a precursor tilt phenomenon
JP2759589B2 (ja) * 1992-12-28 1998-05-28 キヤノン株式会社 強誘電性液晶表示素子
DE69317640T2 (de) * 1992-12-28 1998-07-30 Canon Kk Verfahren und Einrichtung für eine Flüssigkristallanzeige
US5477358A (en) * 1993-06-21 1995-12-19 Case Western Reserve University Chiral nematic liquid crystal display with homeotropic alignment and negative dielectric anisotropy

Also Published As

Publication number Publication date
CN1121231A (zh) 1996-04-24
JP3520122B2 (ja) 2004-04-19
EP0666555A1 (de) 1995-08-09
JPH07218934A (ja) 1995-08-18
KR100254648B1 (ko) 2000-05-01
DE59502715D1 (de) 1998-08-13
HK1011445A1 (en) 1999-07-09
SG47897A1 (en) 1998-04-17
US6163311A (en) 2000-12-19
CN1096051C (zh) 2002-12-11
KR950024139A (ko) 1995-08-21

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