JPH0854603A - Active matrix liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device for which the number of drivers is reduced. SOLUTION: This liquid crystal display device is provided with a display screen with thin film of liquid crystal arranged between electrodes and a plane back surface electrode for which respective pixels are arranged, to correspond to rows and columns. The respective electrodes are connected to a thin-film transistor. Respective conductors, allocated to the line of the pixels in a row direction, are common to a group provided with integer (n) lines in this case, (n) is larger than 1} and a driver circuit 36 for continuously applying plural control voltages during a screen write cycle is provided. The respective conductors allocated to the line of the pixels in a column direction drive only one line. The back surface electrode is subdivided into (n) pieces of parts, respectively provided with a common voltage switching element, and the respective parts are allocated to the corresponding line in the group of the pixels. The switching element provides the back surface electrode with a specified enabling voltage during a period required for controlling one of the (n) lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an "active matrix" type liquid crystal display device. This device has a thin layer of liquid crystal disposed between a planar back electrode and an electrode, each of which cooperates with the back electrode to define a capacitor and a picture element or "pixel". Each pixel is 1
They are arranged to correspond to one row and one column. Each electrode is connected to a control element, such as a thin film transistor, which is common to all pixels in the column to which that electrode depends, depending on the voltage applied to the row conductor common to all control elements in the same row. Of the column conductor of the column, or the role of separating the potential so that the potential floats.

Each control element thus constitutes a switch, which in the closed state allows the electrodes to take the voltage of the column conductors and in the open state to separate the electrodes.

Since it may cause a ghost image,
To prevent residual charge from accumulating, it is common to reverse the polarity of the voltage applied to the capacitor at regular intervals, for example the frame update frequency. Therefore, the average value of the voltage applied to the capacitor of each pixel over time is zero.

For the sake of clarity, the following description is essentially that of a monochrome screen.
However, the present invention is equally applicable to color display screens having at least three sets of green, red and blue pixels.

Each of the L row conductors and each of the C column conductors are connected to a driver circuit which determines the voltage applied to the conductors. Therefore, if there are L × C = P pixels, it is necessary to have L + C drivers.

As the number of drivers increases, so does the price, the complexity of the device and the risk of failure. The larger the screen, the bigger the result. Currently, large size, for example, 1920 x 48 in color screen
It tends to produce screens with zero pixels.

[0007]

SUMMARY OF THE INVENTION The present invention seeks to provide an apparatus of the type described above. Its particular purpose is to reduce the number of drivers.

To this end, the invention provides that each conductor belonging to a line of pixels in the first direction (row or column) is one.
Common to groups having an integer number of lines greater than n and including a single driver circuit designed to provide multiple control voltages in succession during a screen write cycle (or frame cycle); And each conductor assigned to a line of pixels in the second direction (column or row) drives only one line in a second direction orthogonal to the first direction. The back electrode is divided into n parts, each of which is provided with a voltage switch element,
Each part is associated with a corresponding line of the group of lines. Each of the switch elements may be designed to bring a portion of the back electrode to a predetermined enabling voltage for a period of time required to control one of the n lines. One of the conductors associated with each pixel applies a voltage that is the sum of the terms in the orthogonal code weighted at one time, while the conductor in the other direction associated with the same pixel simultaneously represents the terms in the orthogonal code. Is applied.

This arrangement makes it possible to reduce the number of drivers in one of the two directions, and also to reduce the number of connections that have to be made properly between the driver and the screen, and thus the coverage factor of the screen, ie The ratio of the work display area to the total area is increased.

Since each pixel has three control parameters (the voltage applied to the row conductors, the voltage applied to the column conductors, and the voltage of the back electrode) rather than two as in a conventional screen, The light transmission value of a pixel (usually its transparency) is when two rows (or more commonly n rows) are controlled by the same conductor, or two columns (or more commonly n). Can be controlled separately, even if they are controlled by the same conductor.

Electrical control can be provided in various ways. In an embodiment which is particularly advantageous when n is significantly greater than 1 and when the groups are constituted by rows:

Each driver common to the n rows is arranged to perform at least n consecutive sequences of duration (T _i ) during a screen write cycle,
Each including a first part (T _a ) arranged so that all of the electrodes of the group assume the potential of the corresponding column and _a second part (T _m ) in which the previous potential is retained, During the continuous sequence of the same cycle, the switching element of the electrode part has two values (+ V _ce ) and (-V _ce ).
_ce ) arranged to apply a continuous voltage having one or the other of the two, and the sequence of values applied to each back electrode part is a zero mean value code orthogonal to all the codes of the other back electrode parts. , Each of which is controlled to successively take a continuous voltage in the first part of the cycle, each of which has one continuous weighting term of the code assigned to that row in each column. , And the sum of the products of the values representing the parameters representing the emission measurements to be applied to the pixels belonging to both the column and the group.

Instead of having groups of rows, it is possible to have groups of columns. Even in that case, the control can be performed in the above-described manner, but it is replaced by a column.

The relationship between the light transmission value of a pixel in a liquid crystal screen and the voltage across the terminals of the capacitor defining the pixel is not linear. Further, the mode of the control mode is made to have a square error. This is so that each driver performs at least one (n + 1) th sequence in which the column conductor is brought to the product of successive square error corrections with successive terms of the further binary code of zero mean value orthogonal to the other code. Can be corrected by This correction is possible because the error is the same for all pixels in the same column group.

The above-mentioned features, and other features which can be used independently but which are particularly advantageous for use with them, are obtained by reading the description of the following specific examples, given by way of non-limiting example: It will become more apparent.

This description is made with reference to the accompanying drawings.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A conventional active matrix display screen, a portion of which is shown schematically in FIG.
It includes a thin layer of liquid crystal disposed between two transparent sheets.
For screens that function by the transmission of light, the assembly thus formed is provided between the polarizer and the analyzer. One of the sheets carries a single back electrode which constitutes one of the plates 20 of all capacitors, each of which forms one of the picture elements or "pixels". The other transparent sheet supports the control electrodes 22, each defining one pixel and the back electrode 20.
To form a capacitor in cooperation with. These electrodes may be constituted by a deposit of transparent conductive material. In the following, L × C pixels are L rows, L1, L2, L3, ...
And column C, C1, C2, ...

FIG. 1 also illustrates the conventional manner of providing control. Each pixel is controlled by a thin film field effect transistor (commonly referred to as the abbreviation TFT). All transistors T ₁₁ in the same row, eg L1,
T ₁₂ and T ₁₃ are simultaneously rendered conductive by the corresponding conductors of row L1 taking on a predetermined voltage (+15 volts), while the row conductors of all other rows have transistor cut-off voltages (-15 volts). )I take the. The conducting transistor transmits the voltage Vc of the corresponding column conductor to the associated electrode 22. The information constituted by the applied voltage Vc is held for the duration of one frame and the discharge time constant of the capacitor is chosen long enough for this purpose.

Conventionally, the column conductors are controlled from a shift register 24, which constitutes a row memory, and the shifting is done by the time base 2.
It was driven by the clock signal from 6. The data input 28 of the shift register receives the signal via a sample and hold circuit, which is also controlled by the time base 26. When all the information corresponding to the row has been received, it is transferred to the buffer memory 32. The contents of all cells in the buffer memory are
When receiving the probe signal from the driver 34 ₁ , 3
4 _2, each column conductor C1 through ..., C2, simultaneously given to .... The row to receive the information is selected by addressing the driver 36 for the row conductor. The voltage on the back electrode is fixed by the source 37 and typically alternates between the values + V _ce and -V _ce .

Corresponding elements of FIG. 1 are designated by the same reference numerals, and in the particular embodiment of the invention shown in FIG. 2 where each row driver drives two rows and connects the row drivers. They are typically contiguous because they are the simplest solution. For example, the first of the drivers 36
Output of is connected to conductors for rows L1 and L2, and a second output is connected to conductors for rows L3 and L4.

The back electrode is divided into two parts CE1 and CE2 associated with a row in such a way that no two rows having both the same row conductor and the same back electrode portion are present.

If the group contains only n = 2 rows, it is possible to form the back electrode by etching a single conductive layer, in which case both parts have the same electrical resistance. Have.

The physical placement of the conductors and electrodes, and the placement of the mask used to form them may be as schematically shown in FIG. The area shown represents a pixel defining electrode which may be for red pixel R, green pixel V, and blue pixel B. Each electrode has an extension such as D that constitutes the drain of each thin film transistor. Common column conductors,
For example, C1 drives a source such as S of a field effect transistor belonging to a single column. The tracks forming the row conductors form a grid of transistors in two adjacent rows. For example, as shown in FIG. 3, a common row conductor L
12 constitutes the grid of the field effect transistors of the pixels in the two rows L1 and L2 of the matrix, which rows are generally adjacent.

The back electrode does not necessarily have to be divided in the manner shown in FIG. FIG. 5 shows another possible arrangement that makes it easier to etch the two parts CE1 and CE2 by using the planar arrangement of back electrode parts and row conductors shown in FIG. 4, where FIG. Elements corresponding to the elements of are given the same reference numbers.

As mentioned above, it is possible to divide the rows into groups with any integer number of rows, where n is greater than one. Under these circumstances, the back electrode is n
Number of partial CE _1, ..., it is divided into CE _n.

If n = 3, use a back electrode comprising a single etched layer by forming the third portion CE3 into a braided pattern or a lightning pattern as shown in FIG. Is still possible. However, this method has the disadvantage of giving part CE3 an impedance above the other two parts, unless the intermediate supply is provided in the form of a bias through an insulating layer covering the back electrode.

Three transistors belonging to three consecutive rows L1, L2 and L3 but sharing a common row conductor L123 can be controlled if the etching is of the kind shown in FIG. This allows the control transistors to be grouped into a smaller total area. This is because only one etched track is needed for three (and more generally n) rows.

Each column conductor, such as C1, has an extension, each of which constitutes the common source of three transistors belonging to a given column and three consecutive rows. The electrodes of the three corresponding pixels are the drain D of the control thin film transistor.
It has extensions that make up 1, D2, and D3.

It is often appropriate to use a number of n greater than 3 in order to significantly reduce the number of drivers. Especially in the case of a three-color screen, it is often appropriate that n = 6, ie each row conductor is associated with two sets of R, V and B pixels.

With n greater than or equal to 4, it is still possible to arrive at the method as shown in FIG. 6, but with higher resistance in some parts. It is also possible to adopt a two-layer arrangement for the part of the back electrode (this layer is made of stannous indium oxide, commonly known as "ITO"), which is separated by a thin insulating film. It When n = 4, the back electrode portions CE1, CE2,
The relative placement of CE3 and CE4 and some row and column conductors may be as shown in FIG.

Combinations other than those described above and other transistor formation methods are possible. The structure with groups of n = 6 rows and the possible configurations of the electrical parts of the device are described below.

Each part of the back electrode may be constituted by a mosaic of individual tiles etched in a single conductive layer and connected to their respective conductors by VIA holes through an insulating layer.

It is also possible to divide a large display screen into a plurality of rectangular areas and use one of the above arrangements in each area.

As mentioned above, instead of grouping the rows, it is also possible to group the columns. Examples of these groupings will be given in describing the specific structure of the electrical part of the device. One of the possible relative arrangements for a group of three rows is shown in FIG.

It is taken into account that the column conductors receive a voltage which determines the light transmission and the row conductors merely act as a switch control.

It is possible to combine column groups with row groups, but this increases the number of back electrode portions required. More precisely, the number of back electrode parts is equal to the product of the number of rows for one group and the number of columns for one group.

The electric circuit described as an example below can be used when the control element is constituted by a transistor. Under these circumstances, when the row conductor associated with the transistor is brought to the enabling voltage (transistor is in the conducting state), the pixel electrode takes the voltage of the column conductor and when the row conductor is brought to the blocking voltage. , The electrodes are separated and the voltage on the terminals of the capacitor is held, with a reduction due to the gradual discharge of the capacitor.

A group g of n rows located at the intersection of a row group column k
Consider the general case where it is desirable to give the pixels belonging to the j-th row of x to the transmission value represented by the coefficient a _jgk . In particular, attention is paid to the case of n = 6, that is, each group consists of six rows and the back electrode consists of six parts.

A particularly advantageous solution is for each row for a period of time equal to the frame duration T _r divided by the number of rows in the screen (followed by a hold duration representing the rest of the frame duration). Instead of providing individual control separately, each group is in turn globally controlled.
During each frame duration T _r , all transistors in the group under consideration are shut off except during the period T _a assigned to that group. As shown in FIG. 10, it is possible to address each group of rows for a duration belonging to the period T _m of every other group.

The rows in the group have a sequence of at least n consecutive durations T _i , each of which is the same for all rows in the group so that the capacitor electrode takes the potential of its respective column conductor. It includes a first part T _a in which the transistors are made conductive and a second part T _{m in} which all the transistors in the group under consideration are cut off, which is much longer than T _a .

As shown in FIG. 10, it is possible to address each group of rows during the period T _m common to the other rows.

By controlling in this way, it is possible in this case to use an orthogonal code (often binary) consisting of a fixed number of +1 and -1 terms. In an orthogonal code, the sum of the squares of the terms of each code is a common value, which can be 1 according to the standard, and the sum of the products of the terms of any pair of two codes is 0. .

The voltage V _cej applied to the back electrode portion between the successive portions T _a1 and T _a2 is the _product of the common value V _ce and the term in one orthogonal code.

The codes used generally have more than n terms per row, so that additional parameters are available. When the back electrodes are arranged alternately, the number of continuous portions is n + 1, and otherwise, it is n + 2. For example, given the particular case where the group has 6 rows and the back electrode consists of 6 parts, it would be possible to use 8 codes, each with 8 terms. That way, six codes can be assigned to the back electrode portion, another code to compensate for the squared error, and the last code can be left unused.

In particular, except for the unused code f0, it is possible to use the following codes, each having a sum of 0's.

[0046]

[Table 1]

T_rIs divided into eight periods T₁~ T₈of
Voltage V_cejThe value of is the term f₁~ F ₆And V_ceIs the product of
It For example, consecutive periods T_aIn the part CE1 between
The voltage applied is as follows.

[0048]

[Table 2]

This distribution is as shown in FIG.

During the corresponding period T _a , the voltage V _ck applied to the column conductors of order k while the group g is being addressed is given by:

[0051]

[Table 3]

Indexes 1 to 8 simply represent consecutive times.

To ensure that the capacitors of pixels 1-n in a given group g, corresponding to a given column k, have appropriate emission measurements (commonly called light transmission values) during time T. to the order to be fixed by the light transmission duration mean square value between T _r (V _RMS jgk) ² via the pixel row j of the group g at the intersection of the column k,
An appropriate root mean square voltage must be applied to the pixel capacitor.

If n = 6, ie there are 6 pixels in column k, then column k during at least 6 consecutive periods, typically more than 6 consecutive periods to make corrections.
, A6gk, which can be in the range of -1 to +1 for the radiometric parameter representing the transmission value to be given, are determined by applying different voltages to.

In the above case where eight time periods are used, the voltage applied to the column conductors during the interval T _a is dependent on the code term and the parameter assigned to the corresponding row (and corresponding back electrode part). Pixel-wise sum of products and reference voltage V _c
And the product.

That is, ignoring the squared error, the signal sent is as follows: Vc × (+ a1gk + a2gk + a3gk + a4gk + a5gk + a6gk) Vc × (+ a1gk + a2gk-a3gk-a4gk-a5gk-a6gk) Vc × (-a1gk-a2gk + a3gk-a4kkaag (-A1gk-a2gk-a3gk + a4gk-a5gk + a6gk) (1) Vc x (+ a1gk-a2gk + a3gk + a4gk-a5gk-a6gk) Vc x (+ a1gk-a2gk-a3gk-a4kk6a5gk + a4gk6a5gk × (-a1gk + a2gk + a3gk-a4gk-a5gk + a6gk) Vc × (-a1gk + a2gk-a3gk + a4gk + a5gk-a6gk) where × is a symbol for multiplication.

Rows in row group g (or back electrodes) j
And the voltage (Vpi) seen at the pixel at the intersection of column k
x) jck is (Vpix) jgk (t) = VCEj-V
If it is obtained from Ck, the value a1 is obtained for the pixels in the first row, and so on. This voltage is readjusted during each period Ti by the new addressing performed during Ta. It remains at the adjusted value for the subsequent period Tm. This occurs n + 2 times, that is, eight times in succession during the frame period Tr.

However, since the information received by one pixel in a group depends on the information received by other pixels in the group, the error in the signal (1) caused by the essence of the square law of the relation governing the transmission value is You have to make corrections. Theoretically, the error is given by:

[0059]

[Equation 1]

As a result, the following equation holds.

During Ta1, Vc1gk = Vc × (+ a1gk + a2gk + a3g
k + a4gk + a5gk + a6gk + S) While Ta2, Vc2gk = Vc × (+ a1gk + a2gk-a3gk-a4gk-a5gk-
a6gk + S) During Ta3, Vc3gk = Vc × (-a1gk-a2gk + a3gk-a4gk + a5gk-
a6gk + S) During Ta4, Vc4gk = Vc × (-a1gk-a2gk-a3gk + a4gk-a5gk +
a6gk + S) During Ta5, Vc5gk = Vc × (+ a1gk-a2gk + a3gk + a4gk-a5gk-
a6gk-S) During Ta6, Vc6gk = Vc × (+ a1gk-a2gk-a3gk-a4gk + a5gk +
a6gk-S) During Ta7, Vc7gk = Vc × (-a1gk + a2gk + a3gk-a4gk-a5gk +
a6gk-S) During Ta8, Vc8gk = Vc × (-a1gk + a2gk-a3gk + a4gk + a5gk-
a6gk-S) These eight voltage values Vc1gk, ..., Vc8gk are
The voltage value that must be applied to the considered column k during each of the eight periods Ta in order to charge the six pixels of group g and column k.

It can be seen that the pixels in row j, column k in group g always have the voltages shown below.

[0063] _{(Vpix) jgk = V CE xf} j -Vcgk code above all, will be seen to have an average value of 0 over a period Tr. Therefore, the average value (Vpix) jgk over Tr is 0. If the average value of the code is not 0, the thin film transistor (or TF
The "alternating" method, which is the conventional method for addressing T), can be used. Under such circumstances,
It is necessary to have n + 1 orthogonal functions to implement the invention. Illustratively, the fourth row and column k of group g
It can be seen that the root mean square value of the pixels at the intersection with is as follows.

(V _RMS jkg) ² = Vce ² + 6 × Vc
² −2 × a4gk × Vce × Vc where a4gk is in the range of −1 to +1 and can take any intermediate value when it is desirable to display gray values in black and white or unsaturated colors. is there. Therefore, by selecting Vc and Vce, the transmission of light at the corresponding point can be modulated to have any value between its off and on states, ie (V _RMS jgk) ² Is Vce ² + 6 × Vc ² -2
× Vce × Vc or Vce ² + 6 × Vc ² + 2 × Vc
It can take any value within the range of e × Vc.

Group of Columns It is also possible to construct a group of n columns, and this solution makes it possible to reduce the number of column drivers, which is more complicated than the row drivers.

Consider a group g consisting of n columns 1, ..., K, ..., N, and in particular control of pixels at the intersections of columns k and rows j in group g. even here,
The back electrode is subdivided into n separate parts or elements CEk. The first element CE1 is arranged to face the column numbered as 1 in each of the defined groups. The second element CE2 faces the column numbered 2 in each of the defined groups, and the nth back electrode element CEn is the column numbered n in each of the defined groups. Face. Again, the columns in the same group need not be adjacent in the active matrix plate.

The parts of the back electrode or element CE1 are electrically connected to each other in the back electrode plate. In an arrangement that is one of the configurations described above, the back electrode elements CE2 are electrically connected to each other at the back electrode plate, as well as up to CEn.

FIG. 12 exemplarily shows a portion of a device having a group of six columns. 6 lines,
Only the pixels corresponding to n, i.e. one group of 6 columns are shown. The orthogonal code shown on the right side of FIG. 12 is the same as the above-described orthogonal code.

Again, the frame period Tr is subdivided into periods Ti (using the code above, eight periods, including six useful periods and one period which serves to compensate for squared errors). Be done).

The period T during which the transistors in each row j are cut off
During m, any other row of the display screen can be addressed, one at a time.

Here again, it is necessary to provide six pixels, in this case six light transmission values, to the pixel defined by column group g and row j, these light transmission values being applied to each of the pixels. It is represented by the root mean square value of the voltage. The root mean square values of such voltages are intensity parameters ajg1, ajg2, ajg3, ajg4, af.
It changes as a function of g5 and afg6 (-1 <ajgk <+1).

The signals applied to the columns of group g during each of the eight periods Ti without theoretical square error correction are defined in the same way as previously described. Therefore, it becomes as follows.

During Ta1 = Vc × (+ ajg1 + ajg2 + ajg3 + ajg4 + ajg5 + ajg6) During Ta2 = Vc × (+ ajg1 + ajg2-ajg3-ajg4-ajg5-ajg6) ──────── ───────────────── During Ta3 = Vc × (-ajg1 + ajg2-ajg3 + ajg4 + ajg5-ajg6) To correct the root mean square error, the rows are grouped. It is necessary to add the same term S as in the split case, so the continuous voltage to be applied to column k is

During Ta1, Vcjg1 = Vc × (+ ajg1 + ajg2 + ajg
3 + ajg4 + ajg5 + ajg6 + S) While Ta2, Vcjg2 = Vc × (+ ajg1 + ajg2-ajg3-ajg4-ajg5-
ajg6 + S) During Ta3, Vcjg3 = Vc × (-ajg1-ajg2 + ajg3-ajg4 + ajg5-
ajg6 + S) During Ta4, Vcjg4 = Vc × (-ajg1-ajg2-ajg3 + ajg4-ajg5 +
ajg6 + S) During Ta5, Vcjg5 = Vc x (+ ajg1-ajg2 + ajg3 + ajg4-ajg5-
ajg6-S) During Ta6, Vcjg6 = Vc x (+ ajg1-ajg2-ajg3-ajg4 + ajg5 +
ajg6-S) During Ta7, Vcjg7 = Vc x (-ajg1 + ajg2 + ajg3-ajg4-ajg5 +
ajg6-S) During Ta8, Vcjg8 = Vc x (-ajg1 + ajg2-ajg3 + ajg4 + ajg5-
ajg6-S) In fact, these eight voltage values have to be given to all columns of the group g under consideration during each period Ta to electrically charge the six pixels of row j. It is the value of the voltage that does not become.

Since all columns in a given group receive exactly the same electrical signal, the number of column drivers is a factor n,
In this case, it can be seen that division is by 6. This allows
The number of column drivers and the number of electrical connection points between these drivers and the display of the screen are reduced.

The voltage VCEk as applied to the six back electrode elements during these eight periods is shown in the same table as if the rows were grouped rather than columns (assuming the same code). Be done.

For example, while addressing row j, the above voltages are:

[0078]

[Table 4]

The correction and control of the squared error is the same as for the group of rows and will not be discussed further.

[Brief description of drawings]

FIG. 1 is a simplified view of a known structure of a portion of an active matrix liquid crystal monochrome screen.

2 is a view similar to FIG. 1 showing a first device which constitutes a particular embodiment of the invention in which the back electrode has only two parts.

3 is a plan view of a portion of a screen showing one possible appearance of a mask used to make a screen of the type shown in FIG.

4 is a diagram showing a structure in which back electrodes suitable for use in the apparatus shown in FIG. 5 are intermeshed with each other.

FIG. 5 is a view similar to FIG. 3, showing another possible arrangement of the parts of the back electrode with two parts.

FIG. 6 shows the structure of the back electrode, which consists of three parts,
It is a figure similar to FIG.

7 shows a mask suitable for use with a three-part back electrode of the type shown in FIG.
It is a figure similar to FIG.

FIG. 8 is a view similar to FIGS. 4 and 6, showing a possible structure for a two-level back electrode that allows the use of groups of four rows each.

FIG. 9 is a view similar to FIG. 7, showing a suitable mask for use with groups of three columns each.

FIG. 10 is a timing diagram of control signals for a group of columns.

FIG. 11 is a side-by-side view showing a circuit diagram of a group of six rows and a timing diagram of a voltage applied to a corresponding portion of the back electrode.

FIG. 12 is a diagram showing a circuit diagram of a group including six columns and a timing diagram of a voltage applied to a corresponding portion of the back electrode side by side.

[Explanation of symbols]

 24 shift register 32 buffer memory 34 driver 36 driver

Claims (4)

[Claims] 1. An active matrix liquid crystal display device, comprising: a first and a plurality of rows and columns which are orthogonal to each other.
And a display screen defining an array of pixels arranged in lines oriented along a second direction,
The display screen has a planar back electrode means divided into a plurality of mutually insulated parts, and an array of control electrodes regularly arranged on a plane spaced from the back electrode means, Each of the control electrodes defines one of the pixels, each of which constitutes a capacitor with the back electrode means, and further comprises a thin layer of liquid crystal between the back electrode means and the array of control electrodes; A plurality of active control elements connected to one of the control electrodes and a plurality of row conductors, each of the row conductors being common to all active control elements in the same row, each of which is a row In each of the active shut-off elements of the active control element and the enabling voltage for conducting the active control, each of which has a plurality of column conductors, Are common to all active control elements of the same column, each tending to result in an adjustable voltage that can be transmitted to a control element connected to a conducting active control element, in the first direction Each conductor assigned to one of the lines is common to a group of n lines, where n is an integer greater than 1 and each conductor has a plurality of consecutive numbers during a screen write cycle. Each conductor connected to a single common driver circuit configured to apply a second voltage, while each conductor assigned to a line of pixels in the second direction drives only one line in the second direction at a time. And each of the n portions of the back electrode is connected to provide a voltage switching element, each portion being associated with only one line of each of the groups of lines, each of the switching elements being Is designed to bring each one of said portions of the said to a predetermined enabling voltage for a period of time required to control one of the n lines, one first Of successive conductors that make up the weighted orthogonal code term on one of the conductors assigned to the pixels of the line of pixels and represent the orthogonal code term on the conductor in the other direction associated with the same pixel. An active matrix liquid crystal display device, wherein means for applying a voltage are provided. 2. Each of the control electrodes has a conductive extension forming a drain or a source of the respective thin film transistor, and a common column conductor drives all the sources or drains of the thin film transistors belonging to the same group. And the tracks forming the row conductors are n
The active matrix liquid crystal display device according to claim 1, which constitutes a lattice of individual transistors. 3. Each of said groups is constituted by n said rows, n being a predetermined integer less than the total number of said rows, such that during a screen writing cycle all of the electrodes of a group are A sequence of at least n consecutive durations (T _i ) comprising _a first part (T _a ) taking the potential of the corresponding column and _a second part (T _m ) in which the previous potential is retained. A common driver circuit for n rows is designed to perform the following, and the switch element of the back electrode portion has two values (+ V _ce ) and (-V _ce ) during the continuous sequence in the same cycle.
_ce )) designed to apply a continuous voltage with one or the other, the sequence of values given to each back electrode part represents a code of zero mean value orthogonal to all other back electrode part codes, The columns are controlled such that each of them is brought to a continuous and continuous voltage during the first part of the cycle, each of which is in each column one continuous weighted of the code assigned to the row. 2. An active matrix liquid crystal display device as claimed in claim 1, characterized by the sum of the products of the values representing the parameters representing the emission measurements to be given to the pixels belonging to both the term and the columns and groups. 4. The code is at least n + 1 codes, which include at least n + 1 terms, and each column driver is designed to add a term to each of the sums of products, which term is (n + 1). The second term and the squared error (square
law error) a voltage consisting of the product of the correction terms and the sum of the products of the successive terms of an additional binary code of zero mean value orthogonal to another code and the value 4. The active matrix liquid crystal display device according to claim 3, wherein each column driver is designed to execute a (n + 1) th sequence.