EP0614563B1 - Flüssigkristallanseigevorrichtung - Google Patents

Flüssigkristallanseigevorrichtung Download PDF

Info

Publication number
EP0614563B1
EP0614563B1 EP93921094A EP93921094A EP0614563B1 EP 0614563 B1 EP0614563 B1 EP 0614563B1 EP 93921094 A EP93921094 A EP 93921094A EP 93921094 A EP93921094 A EP 93921094A EP 0614563 B1 EP0614563 B1 EP 0614563B1
Authority
EP
European Patent Office
Prior art keywords
line
voltage
value
column
rms
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
EP93921094A
Other languages
English (en)
French (fr)
Other versions
EP0614563A1 (de
Inventor
Theo L. Welzen
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.)
Citizen Watch Co Ltd
Original Assignee
Citizen Watch Co Ltd
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 Citizen Watch Co Ltd filed Critical Citizen Watch Co Ltd
Publication of EP0614563A1 publication Critical patent/EP0614563A1/de
Application granted granted Critical
Publication of EP0614563B1 publication Critical patent/EP0614563B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • G09G3/20—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
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0209—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

Definitions

  • the present invention relates to a display device, comprising a liquid-crystal material between two support plates held at a defined spacing from one another and having surfaces facing one another, a pattern of N line electrodes being provided on one surface and a pattern of column electrodes on the other surface in which the line electrodes cross the column electrodes and a matrix of display elements is thus formed at the position of the crossovers, and the device comprises a control circuit for presenting square-wave data signals to the column electrodes and a line-scanning circuit for periodically scanning the line electrodes and presenting square-wave line selection voltages signals.
  • the first reference shows an addresssable matrix which consists of liquid crystals defined by the crossing regions of row and column electrodes.
  • the state of such a liquid crystal is related to the magnitude of electrical signals applied to those electrodes and to the number of elements in the matrix.
  • the electric signals are modified according to the number of elements in the matrix so that the operating margin between on and off potentials can be maximized.
  • a certain number of columns are scanned and energized in succession while the states of the certain number of elements displayed in each row are prestored and ciculated in a register for that row. Via a circuit the voltage levels for on and off are determined to be applied to the row electrode according to each bit in the register and an elector is operated as each column in turn is scanned.
  • the second reference shows a very similar device where the scanning electrodes are formed on one of two subtrates between which a liquid-crystal-layer is interposed.
  • Scanning electrode voltage driving wave forms consisting of selective and non-selective voltages are applied to the scanning electrodes of the liquid-crystal-panel.
  • Such display devices are normally operated with multiplex addressing in accordance with the so-called RMS mode.
  • the picture elements are switched from a first state to a second state which is optically different therefrom with the aid of the line-scanning circuit which periodically scans the line electrodes with a line-selection pulse of magnitude V s and with the aid of the control circuit for presenting data signals to the column electrodes, which control circuit feeds data voltages of magnitude +/- V d to the column electrodes for the time in which a line electrode is scanned, in such a way that the optical state which is achieved in a display element is determined by the so-called root-mean-square (RMS) voltage value across the element concerned.
  • RMS root-mean-square
  • Figure 2 diagrammatically shows a transmission-voltage characteristic of a picture cell belonging to this display device.
  • Figure 1 diagrammatically shows a portion of a matrix-oriented display device 1 having N max selection lines (row electrodes) 2 and describes the operating principle of the abovementioned RMS multiplex address method.
  • This address method is generally referred to as "line-at-a-time" RMS multiplex addressing.
  • the information to be displayed is presented on the data lines (column electrodes) 3.
  • the display elements 4 are in an on state or an off state.
  • the picture information (data voltage +/- V d ) is supplied synchronously with the selection of the lines or row electrodes with the aid of the line-selection voltage V s .
  • the line 2 a is selected for a period t 1 (also referred to as line time), which line, together with the information then present on the data lines 3 a , 3 b , 3 c (i.e. +/- V d ) determines the optical state of the picture elements 4 aa , 4 bb , 4 cc .
  • the line 2 b is selected for the period t 1 .
  • the information then present on the data lines 3 determines the state of the picture elements 4 ba , 4 bb , 4 bc .
  • the display element responds to the cumulative effect of a number of address pulses (or selection pulses).
  • a liquid-crystal display element responds in the same way as if it has been addressed by a sinusoidal or square-wave signal having the same RMS voltage value as that of the 'on' and 'off' voltages V 2 and V 1 given by the expressions (1) and (2).
  • the maximum number of selection lines N max is related to the value of the ratio V 2 /V 1 (threshold steepness).
  • FRAME RESPONSE This multi-line addressing is used to reduce or to eliminate the so-called "FRAME RESPONSE” behavior.
  • "FRAME RESPONSE” behavior results in loss of contrast and brightness.
  • N max is in turn determined in accordance with expression (3) derived for RMS behavior occurring.
  • the actual RMS voltage value for an "on" element (or selected display element) in a column in which all the picture elements are in the "on” state may differ from the RMS voltage value for a selected display element in a column in which the picture elements are, for example, alternately "on” and "off".
  • crosstalk or “ghost” phenomena
  • ghost perceptible in highly multiplexed dot-matrix liquid-crystal display devices.
  • This method makes use of a special polarity change sequence in which the polarities of the address-voltage signals always change in sign after scanning 2 lines during the raster scan. The start position of these polarity changes is also changed or shifted for successive frames.
  • the object of the invention which will be described in this patent application is to provide a display device in which the abovementioned crosstalk effect is reduced as much as possible without making use of special polarity-change sequences.
  • the control circuit should comprise a "counter unit” which registers the number of "on” -"off" transistions in each column of the matrix of the display device.
  • the (increasing) loss in RMS voltage value over a certain picture element as a consequence of a (increasing) number of "on"-"off" transistions in the column concerned can be compensated for by using a modified (or higher) amplitude of the data voltage during the raster scan.
  • FIG. 3 diagrammatically shows the way in which the voltage V lc across an LC element (represented as a capacitor C) increases with time on presenting a voltage jump of V in in the presence of a resistor R.
  • V RMS 2 (V in 2 /T) ⁇ T C (1 - exp(-t/ ⁇ )) 2 dt
  • V RMS 2 1 - ⁇ /2T * (exp(-2T/ ⁇ ) - 1) + 2 ⁇ /T * (exp(-T/ ⁇ ) - 1)
  • the effective (RMS) voltage is determined by the number of square-wave voltages and therefore, in reality, by the number of passages through zero.
  • Figure 4B diagrammatically shows the voltage across element B with the assumption that only one "on"-"off” transition occurs in column j.
  • V RMS V RMS
  • a data-voltage amplitude which is higher than prescribed according to the Alt and Pleshko relationships (in which case ideal, undeformed square-wave voltage signals are assumed).
  • the height of the data-voltage levels for compensating for V RMS losses can, however, also be determined experimentally by means of transmission (or brightness) measurement of an "on" element as a function of the number of "on"-"off" transitions.
  • transmission (or brightness) measurement of an "on” element as a function of the number of "on"-"off" transitions.
  • the number of voltage levels required can be reduced appreciably because the use of one and the same V d value in the case of, for example, X au and (X au + 1) transitions does not necessarily result in visually perceptible brightness differences.
  • V d values are used for columns with different X au values during the raster scan.
  • V RMS losses as a consequence of "on"-"off" transitions can also be achieved by using the same V d value during the scanning of the N-line matrix for columns having different X au values and by presenting a voltage pulse whose amplitude V j (X au ) is dependent on the X au value in the column concerned simultaneously to the separate columns j after every frame scan for a certain time interval t x (for example, equal to the line time t 1 ).
  • t x for example, equal to the line time t 1 .
  • the height of the voltage pulse to be supplied V j (X au ) can be determined relatively simply experimentally with the aid of transmission measurements according to a procedure such as is described for the determination of the different column voltages V d (X au ) which are used in the first-mentioned compensation method.
  • the polarities of both the data signals and of the line-select signals should change in sign, for example after every raster time; this is done in order to prevent the occurrence of direct-voltage components. In practice, this polarity change is often used after a certain number of line times, the number being less than N.
  • X au can therefore be better interpreted as the number of changes in polarity of V d during a raster time or, still more generally, as the number of times the level of the data voltage changes.
  • FM is described, inter alia, in SID Digest of Technical Papers XIV, pages 32-33, 1983.
  • a disadvantage of FM is the occurrence of "flicker" in fast-switching liquid-crystal display devices.
  • PWM is described, inter alia, in SID Digest of Technical Papers XI, pages 28-29, 1980.
  • PWM has, inter alia, the disadvantage that highfrequency signals are necessary for a large number of grey levels.
  • a third method of achieving grey levels makes use of pulse-height modulation (PHM) and is essentially used in display devices in which each picture element is provided with an active electronic switch such as, for example, a thin-film transistor.
  • PPM pulse-height modulation
  • a grey level is in fact achieved for a picture element by supplying the element concerned with a voltage having a certain amplitude.
  • This method cannot, however, readily be used in the matrix display devices which are described in this patent application and which are addressed by the line-at-a-time or multi-line RMS addressing.
  • V on 2 (V s + V d ) 2 /N + (N - 2)*V d 2 /N + (f*V d ) 2 /N
  • V on 2 (V s + V d ) 2 /N + (N - 2)*V d 2 /N + (f*V d ) 2 /N
  • the loss in RMS voltage can be compensated for by supplying a voltage pulse to the column concerned after each frame scan (for, for example, a line time t 1 ).
  • a voltage pulse for, for example, a line time t 1 .
  • the height of this voltage pulse is dependent on the number of elements in the column concerned having a particular grey level, expressed, for example, in the value of the factor f, in which case completely "on” and completely “off” may also be regarded as grey levels.
  • the height of the voltage pulse can in principle be determined (or calculated) by deriving expressions under these circumstances for, for example, the RMS voltage of an "on” and an “off” element and equating the RMS voltage values calculated in this way to those according to expressions (1) and (2).
  • EXAMPLE 4-line matrix, in which one "on" element and three picture elements having different grey levels (or f values) occur in a particular column.
  • a 5th line is, as it were, added to the 4-line matrix. This line does not actually need to be present: it is a virtual line.
  • V on 2 (S 5 + D 5 ) 2 /5 + (f i *D 5 ) 2 /5 + (f 2 *D 5 ) 2 /5 + (f 3 *D 5 ) 2 /5 + V c 2 /5
  • f i *D 5 is the amplitude of the data voltage which is supplied to the element i concerned having a grey value with parameter value f i .
  • V c 2 /5 arises because, during selection of the 5th (virtual) line, a certain voltage is presented to the column.
  • V f1 2 (S 5 + f 1 *D 5 ) 2 /5 + D 5 2 /5 + (f 2 *D 5 ) 2 /5 + (f 3 *D 5 ) 2 /5 + V c 2 /5
  • V f1 2 (S 4 + f 1 *D 4 ) 2 /4 + (4/4)*D 4 2 - (1/4)*(f 1 *D 4 ) 2
  • V c SQRT((N+1)/N) * SN
  • D N+1 SQRT((N+1)/N) * DN.
  • the height of the voltage pulse V c to be supplied (to the column concerned), which ensures that grey levels can be achieved with the aid of PHM while maintaining the correct RMS voltages of the "on" and "off” elements, can be determined.
  • the device comprises an electronic circuit unit which registers the accosicated value of the parameter X au (j), which is defined in the above mentioned description, for each column j of the matrix of display element s and for each raster scan.
  • the display device of the present invention is further characterized in that during the raster scan, the amplitude V d of the data voltage +/- V d (which is across a picture element during the non-select period in the case of the given description of the line-at-a-time addressing) is different for columns having a different X au value.
  • multi-level data voltages are ures; for example, for 3-line addressing, 4 voltage levels will be used with 2 different amplitudes; +/- V 3 and +/- V 3 /3.
  • V 3 the value of V 3 will be chosen as different, as mentioned above.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Liquid Crystal Display Device Control (AREA)

Claims (1)

  1. Anzeigevorrichtung mit einem Flüssigkristallmaterial zwischen zwei Trägerplatten, die in einem definierten Abstand voneinander gehalten werden und einander zugewandte Oberflächen besitzen, wobei eine Struktur von N Zeilenelektroden auf einer Oberfläche und eine Struktur von Spaltenelektroden auf der anderen Oberfläche vorgesehen sind, wobei die Zeilenelektroden die Spaltenelektroden kreuzen und somit eine Matrix von Anzeigeelementen an der Stelle der Überkreuzungen ausgebildet ist und das Bauelement einen Steuerschaltkreis, um den Spaltenelektroden Rechteckwellen-Datensignale zuzuführen, und einen Zeilenabtastschaltkreis beinhaltet, um die Zeilenelektroden periodisch abzutasten und Rechteckwellen-Zeilenauswahlspannungssignale bereitzustellen;
    dadurch gekennzeichnet, daß die Anzeigevorrichtung eine elektronische Schaltkreiseinheit beinhaltet, die mittels Impulshöhenmodulation Grauwerte erzeugt und den zugehörigen Wert des Parameters Xau (j) registriert, der als die Anzahl von Malen definiert ist, um die sich der Pegel der Datenspannung für jede Spalte j der Matrix von Anzeigeelementen und für jede Rasterabtastung ändert, wobei während der Rasterabtastung die Amplitude Vd der Datenspannung +/- Vd, die während der Nichtauswahl-Periode im Falle der angegebenen Beschreibung der Zeilenadressierung über ein Bildelement hinweg anliegt, für Spalten mit einem unterschiedlichen Xau-Wert unterschiedlich ist und der gewählte Wert von Vd um das Maß größer ist, um das Xau größer ist, und insbesondere gemäß einer Beziehung Vd = Vd (Xau), die dadurch bestimmt ist, daß von der Anforderung ausgegangen wird, daß Bildelemente, von denen angenommen wird, daß sie im gleichen Zustand vorliegen, die jedoch in Spalten mit unterschiedlichem Xau- Wert auftreten, gleiche oder praktisch gleiche VRMS-Spannungen haben müssen, daß des weiteren der gleiche Vd-Wert für einen Bereich von Xau-Werten verwendet wird, nämlich von Xau bis zu einschließlich (Xau + n) mit n = 1, 2, 3, und daß eine geeignete Spannung, deren Amplitude (AMPc) durch den Xau-Wert der betreffenden Spalte festgelegt ist, für ein bestimmtes Zeitintervall nach jeder Rasterabtastung den getrennten Spalten bereitgestellt wird, wodurch der gleiche AMPc-Wert für einen Bereich von Xau-Werten verwendet wird, nämlich von Xau bis zu einschließlich (Xau + n) mit n = 1, 2, 3, ... .
EP93921094A 1992-09-30 1993-09-30 Flüssigkristallanseigevorrichtung Expired - Lifetime EP0614563B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
NL9201692A NL9201692A (nl) 1992-09-30 1992-09-30 Reduktie van Vertikale "Cross-talk" in Dot-Matrix Vloeibaar-Kristal Weergeefinrichtingen, en Realisatie van Grijs-niveau's met behulp van Puls-Hoogte-Modulatie.
NL9201692 1992-09-30
PCT/JP1993/001403 WO1994008330A1 (en) 1992-09-30 1993-09-30 Liquid-crystal display device

Publications (2)

Publication Number Publication Date
EP0614563A1 EP0614563A1 (de) 1994-09-14
EP0614563B1 true EP0614563B1 (de) 1999-01-13

Family

ID=19861323

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93921094A Expired - Lifetime EP0614563B1 (de) 1992-09-30 1993-09-30 Flüssigkristallanseigevorrichtung

Country Status (6)

Country Link
EP (1) EP0614563B1 (de)
JP (1) JPH07501636A (de)
KR (1) KR100343381B1 (de)
DE (1) DE69323059T2 (de)
NL (1) NL9201692A (de)
WO (1) WO1994008330A1 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6693613B2 (en) * 2001-05-21 2004-02-17 Three-Five Systems, Inc. Asymmetric liquid crystal actuation system and method

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2020875B (en) * 1978-05-03 1982-03-03 Marconi Co Ltd Addressable matrices
US5151690A (en) * 1987-08-13 1992-09-29 Seiko Epson Corporation Method and apparatus for driving a liquid crystal display panel
EP0595792B1 (de) * 1988-06-07 1997-08-27 Sharp Kabushiki Kaisha Verfahren und Einrichtung zum Steuern eines kapazitiven Anzeigegeräts

Also Published As

Publication number Publication date
EP0614563A1 (de) 1994-09-14
KR100343381B1 (ko) 2002-11-30
DE69323059T2 (de) 1999-07-15
NL9201692A (nl) 1994-04-18
WO1994008330A1 (en) 1994-04-14
DE69323059D1 (de) 1999-02-25
JPH07501636A (ja) 1995-02-16

Similar Documents

Publication Publication Date Title
US5136282A (en) Ferroelectric liquid crystal apparatus having separate display areas and driving method therefor
EP0366117B1 (de) Flüssigkristall-Vorrichtung
KR100246150B1 (ko) 액정 디스플레이 장치 및 그 구동 방법
EP0358486B1 (de) Methode zum Betrieb einer Flüssigkristallanzeige
US6147792A (en) Light modulating devices
EP0621579B1 (de) Temperaturabhängige , mehrfach verschachtelte Addressierung für Flüssigkristallanzeigen
US5691739A (en) Driving device for a liquid crystal display which uses compensating pulses to correct for irregularities in brightness due to cross talk
US6597335B2 (en) Liquid crystal display device and method for driving the same
JPH10325946A (ja) 光変調装置
EP0587913B1 (de) Flüssigkristallanzeige mit einem adressierungsschema zum erreichen von hohem kontrast und hoher helligkeit mit instandhaltung von schnellem schalten
EP0614563B1 (de) Flüssigkristallanseigevorrichtung
US6069603A (en) Method of driving a matrix display device
US5959602A (en) Liquid-crystal display with addressing scheme to achieve high contrast and high brightness values while maintaining fast switching
JP3896874B2 (ja) 電気光学素子の駆動方法
US5400049A (en) Display control device with compensation for rounded or ringing waveforms
US6028579A (en) Driving method for liquid crystal devices
US6850251B1 (en) Control circuit and control method for display device
KR100627995B1 (ko) 상이한 비디오 표준들로부터의 비디오 신호들을 표시하도록 적용된 매트릭스 디스플레이 장치
JPH08241060A (ja) 液晶表示装置及びその駆動方法
JP2637515B2 (ja) 液晶装置及び液晶素子の駆動法
EP0431628B1 (de) Flüssigkristallanzeigeeinrichtung
JPH1124043A (ja) 液晶表示装置およびその駆動方法
JPH04274286A (ja) 液晶表示装置

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19940520

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB

17Q First examination report despatched

Effective date: 19960618

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE FR GB

REF Corresponds to:

Ref document number: 69323059

Country of ref document: DE

Date of ref document: 19990225

ET Fr: translation filed
PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: FR

Payment date: 20020910

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20020925

Year of fee payment: 10

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20021011

Year of fee payment: 10

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20030930

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040401

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20030930

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20040528

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST