EP0487140B1 - Flüssigkristallanzeigevorrichtungen mit aktiver Matrix und Verfahren zum Betrieb solcher Vorrichtungen - Google Patents

Flüssigkristallanzeigevorrichtungen mit aktiver Matrix und Verfahren zum Betrieb solcher Vorrichtungen Download PDF

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Publication number
EP0487140B1
EP0487140B1 EP19910202929 EP91202929A EP0487140B1 EP 0487140 B1 EP0487140 B1 EP 0487140B1 EP 19910202929 EP19910202929 EP 19910202929 EP 91202929 A EP91202929 A EP 91202929A EP 0487140 B1 EP0487140 B1 EP 0487140B1
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Prior art keywords
field
video signal
picture elements
liquid crystal
fields
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EP19910202929
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English (en)
French (fr)
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EP0487140A1 (de
Inventor
Alan George Knapp
John Revere Mansell
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Philips Electronics UK Ltd
Koninklijke Philips NV
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Philips Electronics UK Ltd
Koninklijke Philips Electronics NV
Philips Electronics NV
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    • 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
    • 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
    • G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
    • 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
    • G09G2320/0252—Improving the response speed
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2340/00—Aspects of display data processing
    • G09G2340/04—Changes in size, position or resolution of an image
    • G09G2340/0407—Resolution change, inclusive of the use of different resolutions for different screen areas
    • G09G2340/0435—Change or adaptation of the frame rate of the video stream

Definitions

  • This invention relates to active matrix liquid crystal display systems, particularly video display systems, for example, for displaying TV pictures, and to methods of operating such systems.
  • the invention concerns active matrix liquid crystal display systems of the kind comprising a display panel having a row and column array of liquid crystal picture elements each of which is controlled by an associated switching device, input means for receiving a video signal, and drive means for driving the picture elements in accordance with the video signal, the picture elements being driven a row at a time by scanning the rows in sequence during each successive field period.
  • Liquid crystal video display systems for displaying TV pictures and the like are well known. Larger area displays commonly include an active switching device associated with each picture element in order to obtain sufficient display quality. These switching devices typically consist of TFTs or two-terminal non-linear devices such as diode or MIM elements. In the case of a simple and typical TFT addressed display system for example, a picture element electrode is connected to the drain of an associated TFT. The gates of the TFTs of all picture elements in the same row are connected to a common row, scanning, address conductor and the source of the TFTs of all picture elements in the same column are connected to a common column address conductor to which video information, data, signals are supplied.
  • the picture elements are driven one row at a time in sequence by scanning the row conductors with gating signals.
  • Video information signals derived by sampling the video signal, for example TV signal, and determining the display output to be obtained from the row of picture elements, are applied to the column conductors and transferred to the corresponding picture element electrodes upon the TFTs being gated. After all rows have been driven, the operation is repeated with each row being addressed in successive field periods.
  • the scanning, and hence field, frequency is determined by timing signals in the input video signal and the field rate of the display panel corresponds to that of the supplied video signal.
  • each line period, during which, or in the interval between successive line periods, a row of picture elements is addressed is 64 microseconds and a field has a duration of 20 milliseconds.
  • the length of a picture element charging (row address) period is determined by the video standard which, in the case of PAL, gives a maximum time of one TV line, i.e. 64 milliseconds for half resolution displays. This in turn determines the switching device's current which should be large enough to charge the picture element capacitance to that of the sampled video voltage in the charging period.
  • the switching device is off, effectively isolating the picture element, so that the charge is stored on the picture element and the display effect produced by the picture element maintained until the element is next addressed in the subsequent field period, although some decay is likely due to the non-perfect characteristics of the liquid crystal material.
  • TV displays set demanding requirements as regards the ability to provide grey scales, full colour, good uniformity, high contrast and brightness, and a rapid response speed.
  • active matrix addressing using for example TFTs, and twisted nematic liquid crystal materials have enabled many of these requirements to be satisfied to an extent.
  • the response time of the display should ideally be such that about 90% of any change in brightness takes place within one field period (i.e. about 20ms) if no obvious movement artifacts are to occur.
  • one field period i.e. about 20ms
  • known liquid crystal display systems respond to changes in applied video voltage much slower and changes in brightness of the output from a picture element commonly takes place continuously over a time greater than a field period so that smearing can occur. Improvements in twisted nematic liquid crystal materials and the use of thinner layers of material at the picture elements have helped to reduce this response time so that reasonable dynamic performance for TV applications and the like can be achieved. However, further improvement in this respect is considered necessary.
  • a method of reducing picture element response time of an active matrix liquid crystal display system comprising a liquid crystal display panel having a row and column array of picture elements each associated with an active switching device, and drive means for driving the rows of picture elements in sequence according to a video signal of a given field rate supplied to the drive means by scanning the rows of the array in succession and supplying sampled fields of the video signal to the columns of the array, which is characterised in that the picture elements of the panel are driven at a field rate higher than that of the video signal supplied to the drive means with fields of the supplied video signal being loaded into field store means of the drive means whose contents are read out at a rate faster than that of loading for use in driving the picture elements.
  • an active matrix liquid crystal video display system comprising a display panel having a row and column array of liquid crystal picture elements each associated with a switching device, input means for receiving a video signal of a given field frequency and drive means for driving the picture elements a row at a time according to the input video signal by scanning the rows of the array in succession and supplying sampled fields of the video signal to the columns of the array, is characterised in that the drive means is operable to reduce picture element response time by driving the array of picture elements at a field rate greater than that of the input video signal and includes field store means into which picture information of an input video signal field is loaded and whose contents are arranged to be read out at a rate faster than that of loading for driving the picture elements according to the picture information of a stored field.
  • the time taken for the transmission of a liquid crystal picture element to stabilise after a change in the drive (video) level can be reduced by increasing the field rate.
  • the response of the picture element transmission to changes of drive level from 90% transmission to 10% transmission and back, driven at the normal (standard) field time of 20ms it typically takes several fields for the transmission to settle to its new level.
  • the picture element Upon reducing the field time, however, the picture element achieves the new level in a significantly shorter time.
  • the response time of the picture elements to changes in drive level can be reduced simply be increasing the field rate at which the elements are operated.
  • picture elements in the one portion and the other portion respectively receive stored and real time video signals, and so on. Consequently, picture elements in each of the two display portions receive both real time and stored video signals once in every normal field period whereby display flicker is reduced compared with conventionally driven display devices. In effect, the field frequency of the voltage applied to liquid crystal picture elements is raised. However, there is no suggestion in this disclosure that the response time of the picture elements might be affected in any way. It is to be noted also with the disclosed drive scheme that successively addressed rows of picture elements, one in each display portion, lie in opposite halves of the display rather than being physically adjacent, and that this requires complicated interconnection between the array and a row drive circuit.
  • EP-A-0254805 there is described a method of driving a liquid crystal display device whose picture elements have just two possible gradations, or states, and are driven using binary signals.
  • the picture element display signals are converted into sequences of binary signals according to their values and these sequences are applied to the picture elements in a series of successive fields occupying a normal frame period which, by virtue of a viewer's persistence of vision, can be interpreted as a multi-gradation display output.
  • an N gradation level output can be obtained over N-1 fields.
  • the picture elements are not supplied with the complete picture information according to the video signal but with binary signals which form only part of the picture information. As a consequence, no improvement in response time of the picture elements could be expected.
  • the increased field rate at which the picture elements are driven is an integral multiple of the field rate of the input video signal.
  • the field rate of the picture elements is chosen to be two to four times the field rate of the supplied video signal.
  • the field rate for the display panel may be increased to 100Hz and 120Hz respectively.
  • the display system which is intended for displaying video, for example TV, pictures, comprises an active matrix addressed liquid crystal display panel 10 having a row and column array of picture elements which consists of m rows (1 to m) with n horizontally arranged picture elements 12 (1 to n) in each row. Only a few of the picture elements are shown for simplicity. In practice, the total number of picture elements (mxn) in the matrix array may be several hundreds of thousands.
  • the display panel 10 is of generally conventional form.
  • Each picture element 12 is associated with a respective switching device in the form of a thin film transistor, TFT, 11 and is located adjacent the intersection of sets of row and column address conductors 14 and 16 with the boundaries of the picture elements being determined by the spacing between adjacent pairs of the row and column conductors.
  • the gate terminals of all TFTs 11 associated with picture elements in the same row are connected to a common row conductor 14 to which, in operation, switching (gating) signals are supplied.
  • the source terminals associated with all picture elements in the same column are connected to a common column conductor 16 to which data (video information) signals are applied.
  • the drain terminals of the TFTs are each connected to a respective transparent picture element electrode 18 forming part of, and defining, picture element.
  • the row and column conductors 14 and 16, TFTs 11 and electrodes 18 are all carried on a transparent plate, for example of glass. Parallel to and spaced from this plate is a further transparent plate on which is formed a continuous transparent conductive layer constituting an electrode common to all the picture elements of the panel. Twisted nematic liquid crystal material is disposed between the two plates, the two plates being suitably sealed around their periphery.
  • the opposing plates are provided with polariser layers in conventional manner.
  • the display panel is illuminated by a light source disposed on one side and light entering the panel is duly modulated according to the transmission characteristics of the picture elements 12.
  • the liquid crystal material modulates light transmitted through the picture elements according to the voltage applied thereacross, with each picture element, defined by the electrode 18 on one plate, an opposing portion of the common electrode on the other plate and the liquid crystal material therebetween, being operable to vary light transmission through the panel in accordance with a drive voltage applied across its respective electrodes.
  • the device is driven on a row at a time basis by scanning the row conductors 14 sequentially with a gating (selection) signal so as to turn on each row of TFTs in turn and applying data, i.e.
  • each row of picture elements is provided with picture information signals corresponding to a TV line.
  • the TFTs 11 of the row are turned off thereby isolating the picture elements from the conductors 16 and ensuring the applied charge is stored on the picture elements.
  • the picture elements stay in the state into which they were driven until the next time they are addressed.
  • the row conductors 14 are supplied successively with gating signals by a row driver circuit 20 comprising a digital shift register controlled by regular timing pulses from a timing and control circuit 21 to which a synchronisation signal is applied from a synchronisation seperator 26. In the intervals between gating signals the row conductors are supplied with a substantially constant reference potential by the drive circuit 20.
  • Video data, picture information, signals are supplied to the column conductors 16 from a column driver circuit 22 comprising one or more shift register/sample and hold circuits.
  • the circuit 22 is supplied with video data signals from a video processing circuit 24 and derived from a video (TV) signal containing picture and timing information and having a given field rate which is supplied to an input 25.
  • Timing signals derived from synchronisation signals obtained in the synchronisation separator 26 from the timing information of the input video signal are supplied to the circuit 22 by the timing and control circuit 21 in synchronism with row scanning to provide serial to parallel conversion appropriate to the row at a time addressing of the panel 10.
  • the circuits 20, 22, 24 and 26 are of generally conventional form and as such will not be described here in detail.
  • a very basic form of column driver circuit 22 is shown schematically in Figure 1 for simplicity and it should be understood that other types of circuit may be employed as will be apparent to persons skilled in the art.
  • the polarity of the drive signals applied to the picture elements is periodically inverted, in accordance with known practice, although the means by which this is achieved is not shown in Figure 1 for simplicity. This polarity inversion can take place after every complete field of the display panel.
  • successive gating signals from the row driver circuit 20 are applied to the row conductors in synchronism with TV lines with each gating signal having a duration corresponding to a TV line period, T1, or less.
  • T1 a TV line period
  • T2 a TV line period
  • T1 a TV line period
  • T2 a TV line period
  • the display panel is driven at a field rate which is greater than the field rate of the input video, TV, signal.
  • This leads to improvement in response time over conventionally-driven display systems. More particularly, the transmission response time of the picture elements, that is, the time taken for the transmission of a picture element to stabilise after a change in the applied drive level, is reduced by increasing the field rate so that the elements are driven more rapidly.
  • the picture elements of the display panel 10 of the system embodiment of Figure 1 are driven at a field rate which is twice that of the standard TV signal supplied.
  • a field rate which is twice that of the standard TV signal supplied.
  • a PAL TV display signal having a field time of 20 milliseconds and a 50 Hz field rate this means that the field time of the display panel is reduced to 10 milliseconds with the field rate in effect being converted to 100Hz.
  • the video signals from the input 25 are fed via an analogue to digital converter 27 and a change-over switch 28 into one of two digital field stores 30 and 31 which holds the digitised video signals for a complete TV field.
  • the change-over switch 28 is operated, under the control of the circuit 21, such that alternate TV field signals are stored in the stores 30 and 31 respectively. While one store, e.g. 30, is being loaded the contents of the other store, 31, are read out and supplied via a change-over switch 32, also controlled by the circuit 21, and a digital to analogue converter 33 to the video processing circuit 24.
  • the stored signals in one store are read out line by line to the circuit 24, each read-out taking half a TV line period.
  • the process is repeated so that the two successive, and identical, field read-outs from a store occupy one standard TV field period.
  • the change-over switches 28 and 32 are operated so that the next TV field signals are read out to the circuit 24 from the other store, again twice in succession in identical manner, while the next TV field is being loaded into the first store. This operation is repeated continuously.
  • Figures 2 to 5 illustrate graphically the effect of changing the display field rate, and more precisely the relationship between transmission and time of an individual picture element for different field rates. Because it is difficult to study the behaviour of a typical picture element of the display panel 10 in situ, large-scale picture elements, approximately 50mm square driven by an FET to simulate the matrix drive device were fabricated for the purpose of making the measurements depicted in these figures. The measurements were made under simulated TFT drive with two different amplitudes for the source waveform being set up. The FET input amplitude is switched between the two levels using a gate waveform derived by dividing the source waveform so as to provide synchronism. The transmission of the picture elements is measured using a light source and photodiode.
  • Figures 2 and 3 show respectively the transmission, Tr, against time, t, characteristic for light-to-dark and dark-to-light transitions in the case of picture element, or cell, A using a commercially available twisted nematic liquid crystal material and polyimide alignment layers.
  • Figures 4 and 5 show respectively the transmission, Tr, against time, t, characteristic for light-to-dark and dark-to-light transitions in the case of cell B which uses a different commercially available TN LC material and the same polyimide, alignment layers.
  • Measurements of transmission against time were taken using three different field rates, namely 25Hz, 50Hz and 100Hz corresponding to field times, 40ms, 20ms, and 10ms respectively, and the measured results for each field rate are shown in the graphs, and identified by the labelling accordingly.
  • the light to dark response is found to be faster than the dark to light.
  • the LC material of cell B has a higher resistivity than that of cell A. Even so, the response time of the cell with the former material is found to be much the same as the latter. Taken at a temperature of 22 degrees centigrade, and for a field rate of 50Hz, the response times of cell A are 35ms for light to dark and 45ms for dark to light transition and the response times of cell B are 30ms for light to dark and 44ms for dark to light.
  • the cells A and B are switched at t equal to 40ms.
  • the cells are switched to the different state after eight successive field periods.
  • the cell A driven at a field rate of 100Hz is switched again from dark to light after 80ms (eight times 10ms), namely at t equal to 120ms.
  • the time scale in the graphs is too short to illustrate the next change in the case of 25Hz driving.
  • the cells A and B When driven with a field period of 20ms, the cells A and B take several fields for the transition to settle to its new level. However, when the cells are driven with a reduced field time of 10ms, they settle down more quickly to the new level.
  • the transmission curve with active drive, depends upon the field rate. Generally, the values of the threshold and saturation voltages in the transmission curve increase with the increased field times. This is because leakage causes the RMS voltage across the cell to be less than the drive voltage. The longer the field time, the more the transmission curve departs from the direct drive case. This leakage can cause ripple at the field rate on the light transmitted by the liquid crystal cell.
  • the actual voltage on the cell decays due to leakage.
  • the transmission starts to fall at a rate dictated by the time taken for the LC molecules to realign themselves.
  • the voltage across the cell is falling, due to leakage, and eventually a stage is reached where the voltage across the cell has decayed to the extent that the transmission is too low for the instantaneous applied voltage and the transmission rises again until the end of the field period when the voltage is refreshed and the process starts once more.
  • the decay time constant is in excess of 10 seconds so voltage decay has little effect on the shape of the response curve during transitions. The main effect here is due to the delay in dielectric constant change.
  • Figures 4 and 5 also show that the curves for the three field rates follow one another for the first 10ms after the drive level is switched. The 20ms and 40ms field time curves then remain together until 20ms has elapsed.
  • the process can be examined in more detail in Figure 6 which shows the transmission, Tr, and cell voltage, V, in the 50ms following a light-to-dark transmission for 10ms and 20ms field times. Immediately after the drive level increase, the molecules start to realign themselves in the increased electric field. This causes the transmission to fall and the dielectric constant to increase.
  • the voltage and transmission for the 20ms field rate continues smoothly.
  • the cell is readdressed after 10ms and the voltage is increased to its initial value of 6.2 volts but negatively this time in accordance with a conventional field inversion drive scheme to avoid degradation of the LC material.
  • This restoration of the cell voltage results in an increase in the change in transmission and the curve for the 10ms field rate starts to fall more rapidly.
  • readdressing takes place for the 20ms field time case.
  • the voltage across the cell increases and there is a discontinuity in the transmission curve. The important point is that the more rapid addressing of the cell at the higher field rates causes the cell to reach its equilibrium value more quickly, i.e. the response time is decreased.
  • the reduction in response time is an important factor for high quality displays when using the display panel as part of a projection television system for large picture sizes and particularly for high definition television.
  • the polarity of the picture element driven voltages may be reversed after every two display fields rather than after every successive display field.
  • the display field rate is twice that of the input video signal
  • the display field rate may be an integral multiple of the input video greater than two.
  • the integral multiple is between 2 to 4.
  • the contents of the field store are read-out the appropriate number of times in each video signal field period.
  • the LC display panel may be of the active matrix type employing two terminal non-linear devices, such as diode elements or MIMs, as active elements for the picture elements rather than TFTs.
  • More sophisticated techniques recently developed for HDTV CRT displays may be used to advantage in that in addition to a response time improvement a higher quality picture can be obtained.
  • a preferred technique in this respect is that of motion compensation. With this technique, achieved by a more complex field-rate converter circuit, an intermediate field is added for display by the panel which is not merely a repetition of the preceding field but instead is derived from it and the next, proper, field by appropriate signal processing so that the sequence of display fields become A A/B B B/C C, etc.

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  • Crystallography & Structural Chemistry (AREA)
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  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
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  • Liquid Crystal Display Device Control (AREA)
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Claims (8)

  1. Verfahren zum Reduzieren der Bildelementansprechzeit einer Flüssigkristallanzeigeanordnung mit aktiver Matrix mit einem Flüssigkristallanzeigefeld (10) mit einer Zeilen- und Spaltengruppe von Bildelementen (12), die mit je einer aktiven Schaltanordnung (11) verknüpft sind, und mit Steuermitteln (20 bis 22, 24 bis 26) zum sequentiellen Steuern der Zeilen von Bildelementen entsprechend einem Videosignal mit einer vorgegebenen Halbbildgeschwindigkeit nach den Steuermitteln durch aufeinanderfolgendes Abtasten der Zeilen der Gruppe und durch Ausgeben abgetasteter Halbbilder des Videosignals nach den Spalten der Gruppe, dadurch gekennzeichnet, daß die Bildelemente des Feldes mit einer höheren Halbbildgeschwindigkeit gesteuert werden als die von den Steuermitteln, wobei die Halbbilder des ausgegebenen Videosignals in Halbbildspeichermittel (27, 28, 30 bis 33) der Steuermittel eingeschrieben werden, deren Inhalte zur Verwendung beim Steuern der Bildelemente mit einer höheren Geschwindigkeit als die des Eingebens gelesen werden.
  2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Halbbildgeschwindigkeit des Anzeigefeldes das n-Fache der Halbbildgeschwindigkeit des ausgegebenen Videosignals ist, worin n gleich 2, 3 oder 4 ist.
  3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Halbbildspeichermittel zum Erzeugen einer Sequenz von Anzeighalbbildern arbeitet, die Wiederholungshalbbilder umfaßt.
  4. Verfahren nach Anspruch 3, dadurch gekennzeichnet, daß abwechselnde Halbbiler des ausgegebenen Videosignals in zwei jeweilige Halbbildspeicher (30, 31) eingegeben werden, wobei der Inhalt des einen Halbbildspeichers zur Verwendung beim Steuern der Bildelemente mehrmals gelesen wird, während ein Halbbild des Videosignals in den anderen Halbbildspeicher eingeschrieben wird.
  5. Flüssigkristallvideoanzeigeanordnung mit aktiver Matrix mit einem Anzeigefeld (10) mit einer Zeilen- und Spaltengruppe von Flüssigkristallbildelementen (12), die mit je einer Schaltungseinrichtung (11) verknüpft sind, mit Eingangsmitteln (25) zum Empfangen eines Videosignals mit einer vorgegebenen Halbbildfrequenz und mit Steuermitteln (20 bis 22, 24, 26) zum Steuern der Bildeelemente Zeile für Zeile entsprechend dem Eingangsvideosignal durch aufeinanderfolgendes Abtasten der Zeilen der Gruppe und durch Ausgeben abgetasteter Halbbilder des Videosignals an die Spalten der Gruppe, dadurch gekennzeichnet, daß das Steuermittel zum Reduzieren der Bildelementansprechzeit betreibbar ist, in dem die Gruppe von Bildelementen bei einer höheren Halbbildgeschwindigkeit als die des Eingangsvideosignals gesteuert wird, und Halbbildspeichermittel (27, 28, 30 bis 33) enthält, in die Bildinformation eines Eingangsvideosignalhalbbildes eingeschrieben wird, und dessen Inhalte zum Steuern der Bildelemente entsprechend der Bildinformation eines gespeicherten Halbbildes bei einer höheren Geschwindigkeit als die der Eingabe ausgelesen werden.
  6. Flüssigkristallvideoanzeigeanordnung mit aktiver Matrix nach Anspruch 5, dadurch gekennzeichnet, daß das Steuermittel zum Steuern des Anzeigefeldes bei einer Halbbildgeschwindigkeit angeordnet ist, die das n-Fache von der des Eingangsvideosignals ist, worin n gleich 2, 3 oder 4 ist.
  7. Flüssigkristallvideoanzeigeanordnung mit aktiver Matrix nach Anspruch 5 oder 6, dadurch gekennzeichnet, daß das Halbbildspeichermittel zum Erzeugen einer Sequenz von Anzeigehalbbildern mit Wiederholungsshalbbildem an seinem Ausgang angeordnet ist.
  8. Flüssigkristallvideoanzeigeanordnung mit aktiver Matrix nach Anspruch 7, dadurch gekennzeichnet, daß das Halbbildspeichermittel erste und zweite Halbbildspeicher (30, 31) enthält, in die abwechselnde Eingangsvideosignalhalbbilder eingeschrieben werden, und daß das Steuermittel derart angeordnet ist, daß es die Inhalte des einen Halbbildspeichers liest und die Bildelemente dementsprechend mehrmals steuert, während der andere Halbbildspeicher mit einem Videosignalfeld geladen wird.
EP19910202929 1990-11-19 1991-11-12 Flüssigkristallanzeigevorrichtungen mit aktiver Matrix und Verfahren zum Betrieb solcher Vorrichtungen Expired - Lifetime EP0487140B1 (de)

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GB9025080A GB2249855A (en) 1990-11-19 1990-11-19 Active matrix liquid crystal video display systems.
GB9025080 1990-11-19

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EP0487140A1 EP0487140A1 (de) 1992-05-27
EP0487140B1 true EP0487140B1 (de) 1996-03-06

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DE69117665D1 (de) 1996-04-11
EP0487140A1 (de) 1992-05-27
DE69117665T2 (de) 1996-09-19
GB9025080D0 (en) 1991-01-02
GB2249855A (en) 1992-05-20

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