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
  • G09G3/3648—Control of matrices with row and column drivers using an active matrix
  • G09G3/3655—Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• • 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
  • G09G3/3614—Control of polarity reversal in general

Definitions

• the present invention relates to a liquid crystal display screen device, called an active matrix device, comprising a thin layer of liquid crystals disposed between a planar counter electrode and control electrodes each defining a capacitor and an image element with the counter-electrode arranged so that each of the points of the image corresponds to a line and a column, each control electrode being connected to a control element, such as a thin film transistor, allowing or carrying it to the potential of a conductor which is common to all the elements of the column to which it belongs, or to isolate it and make its floating potential.
• a control element such as a thin film transistor
• the counter-electrode constitutes a potential plane covering the entire screen.
• Means are often provided for varying the potential of the counter-electrode, in order to reduce the voltage dynamic range required on the column conductors, which receive the information.
• the counter-electrode retains a fixed polarity Vce + or Vce- for the entire duration of a line. Ordering is made easier. On the other hand, it is difficult to obtain a sufficiently rapid convergence of the information presented on each of the column conductors, because the polarity of this conductor is reversed on each line, that is to say at a frequency of a few tens of KHz in the case of a 625-line television type image.
• the invention aims to provide a display screen of the type defined above, responding better than those previously known to the requirements of practice.
• the invention provides a device having a screen whose counter-electrode consists of two fractions provided with means making it possible to bring them to different potentials, reversed at each frame or a multiple of the frame frequency and in which two successive columns (or two groups of a few columns) of control electrodes cooperate with different fractions. These potentials can be equal and of opposite polarities.
• the counter-electrodes will generally consist of interdigitated conducting equipotential planes, the fingers of which have a width corresponding to that of a column of picture elements, in order to give a maximum value to the spatial frequency of flickering.
• FIG. 1 shows a classic constitution an active matrix liquid crystal display screen
• FIG. 2 is a block diagram of a display device control mode, usable with the active matrix screen of Figure 1;
• FIG. 3 shows a possible construction in accordance with the invention, of a counter-electrode for a screen of the kind shown in FIG. 1.
• the display screen shown in FIG. 1 is of the monochrome type. It comprises a thin layer 10 of liquid crystals placed between two transparent plates 12 and 14 carrying electrodes. In the case of a screen working in transmission, the assembly thus formed is mounted between a polarizer 16 and an analyzer 18.
• One of the blades, 12 for example, carries a counter-electrode 20.
• the other blade, 14 for example, carries control electrodes 22 each defining an image element and constituting a capacitor with the counter-electrode 20.
• These electrodes can be formed by transparent conductive deposits.
• An advantageous control mode is shown diagrammatically in FIG. 2, for two picture elements belonging to the same column, therefore associated with the same column conductor 24 and belonging to two successive rows i and i + 1.
• Each picture element is controlled by an element, generally constituted by a field effect transistor, shown diagrammatically in the form of a switch 26 pq and 26 p + lq .
• All the transistors of the same line are made simultaneously conductive by carrying the line conductor 28 corresponding to a determined potential (for example +15 Volts) while the line conductors of all the other lines are brought to a blocking potential of the transistors (for example -5 Volts).
• the transistor 26 pq is shown to be on, while the transistors of the other lines are blocked.
• the pass-through transistors communicate the voltage Vc of the column conductor corresponding to the associated control electrode. The training is then kept for throughout the duration of the frame.
• the counter-electrode 20 is in two fractions 20 j , for example associated with all the columns 20 even, and 20 2 , which is then associated with all the columns even.
• the polarity of each fraction alternates between Vce + and Vce- values, the polarities of the two fractions being always opposite. This result can be achieved using a sequencer 30 controlled by a clock signal H at the frame frequency.
• the control mode of the switching elements can be the same as in the case of a conventional device of the kind shown in FIG. 2.
• the control voltages to which the column conductors, such as the conductor 24, will be applied providing the video information will depend, for a given result, on the column ordered.

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• Engineering & Computer Science (AREA)
• Power Engineering (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)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9431453

Family Applications (1)

Country Status (6)

Families Citing this family (12)

Family Cites Families (7)

• 1992
  • 1992-07-02 FR FR929208159A patent/FR2693305B1/fr not_active Expired - Fee Related
• 1993
  • 1993-07-01 WO PCT/FR1993/000668 patent/WO1994001801A1/fr not_active Application Discontinuation
  • 1993-07-01 US US08/199,291 patent/US5448385A/en not_active Expired - Fee Related
  • 1993-07-01 CA CA002116693A patent/CA2116693A1/fr not_active Abandoned
  • 1993-07-01 JP JP6503017A patent/JPH06510609A/ja active Pending
  • 1993-07-01 EP EP93914793A patent/EP0602218A1/de not_active Ceased

Non-Patent Citations (1)

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