JP3357173B2 - Driving method of image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal which responds at high speed.
The present invention relates to a method for driving a suitable liquid crystal display device. In particular, the book
The invention is an MLSDriving methodMethod (Simultaneous selection of multiple lines)Driving method
Method, Japanese Patent Application Laid-Open No. 6-27907, US Pat.
Simple matrix type that performs multiplex drive with
The present invention relates to a method for driving a liquid crystal display device.

[0002]

2. Description of the Related Art Hereinafter, in this specification, a scanning electrode is called a row electrode and a data electrode is called a column electrode.

[0003] With the advance of the advanced information age, the demand for information display media is increasing more and more. Liquid crystal displays have advantages such as thinness, light weight, and low power consumption, and are expected to become more and more popular with semiconductor technology. On the other hand, with the spread of the screen, a large screen and a high definition have been required, and a search for a method of displaying a large capacity has begun. STN (super twisted nematic) system among the manufacturing process compared to TFT (thin film transistor) method is simple, is considered to be the mainstream in the future liquid crystal display so kills with production at low cost.

[0004] In order to perform large-capacity display by the STN method, a line-sequential multiplex driving method has been conventionally performed.
In this driving method, each row electrode is sequentially selected one by one, and a column electrode is selected corresponding to a display pattern to be displayed . When all the row electrodes are selected, the display of one screen is completed.

However, the line sequential driving how, as the display capacity increases, are known to occur problem called frame response. In the line sequential driving how relatively large at the time of selection, at the time of non-selection relatively small voltage is applied to the pixel. This voltage ratio generally increases as the number of row lines increases (as the duty becomes higher). Therefore, when the voltage ratio is small, the liquid crystal responding to the effective voltage value responds to the applied waveform. In other words, the frame response is a phenomenon in which the transmittance at the time of OFF increases because the amplitude of the selection pulse is large, and the transmittance at the time of ON decreases because the cycle of the selection pulse is long , resulting in a decrease in contrast.

There is known a driving method in which the frame frequency is increased in order to suppress the occurrence of the frame response, thereby shortening the period of the selection pulse. However, this has a serious drawback. That is, when the frame frequency is increased, the frequency spectrum of the applied waveform is increased, which causes non-uniform display and increases power consumption. In order to prevent the selection pulse width from becoming too narrow, the upper limit of the frame frequency is limited.

[0007] In order to solve this problem without increasing the frequency spectrum, recently, new drive how has been proposed. This is an MLS driving method for simultaneously selecting a plurality of row electrodes (selection electrodes). This driving method selects multiple row electrodes simultaneously,
And can independently in controlling the column direction of the display pattern, it is possible to shorten the frame period while maintaining the selected width constant. That is, high-contrast display with suppressed frame response can be performed.

[0008]

In MLS driving how [0005] In order to control the column display pattern independently applied constant voltage pulse train to each row electrodes to be simultaneously applied. That is, voltage pulses are applied to multiple row electrodes simultaneously.
It is . At this time, in order to simultaneously and independently control the display patterns in the column direction, it is necessary to apply pulse voltages having different polarities to the row electrodes. A pulse having polarity is applied to the row electrode several times, and as a whole, each pixel is turned on,
An effective voltage corresponding to the off state is applied.

The selection pulse voltage group applied to each row electrode can be represented as a matrix of L rows and K columns (hereinafter referred to as a selection matrix (A)). Since the selection pulse voltage sequence can be expressed as a group of vectors orthogonal to each other, a matrix including these as column elements is an orthogonal matrix. At this time, each row vector in the matrix is orthogonal to each other. The number L of rows corresponds to the number of simultaneous selections, and each row corresponds to each line. For example, L
The element of the first row of the selection matrix (A) is applied to the line 1 of the selection lines, and the selection pulse is applied in the order of the element of the first column and the element of the second column. In the present specification, in the notation of the selection matrix (A), 1 represents a positive selection pulse, and −1
Means a negative selection pulse. FIG. 7A shows a Hadamard matrix as a typical example of the selection matrix (A).
Shown in FIG. 7A shows an example of four rows and four columns.

A voltage level corresponding to each column element of the matrix and the column display pattern is applied to the column electrodes. That is, the column electrode voltage sequence is determined by the matrix that determines the row electrode voltage sequence and the display pattern.

The sequence of the voltage waveform applied to the column electrode is determined as follows. This will be described with reference to FIG.
The display data at column electrode i and column electrode j is shown in FIG.
The state shown in FIG. Figure 7 shows the column display pattern
This is represented as a vector (d) as shown in FIG. Here, when the column element is -1, on display is shown, and 1 indicates off display. Assuming that row electrode voltages are sequentially applied to the row electrodes in the order of the columns of the matrix, the column electrode voltage level is as shown in FIG.
The waveform becomes like a vector (v) shown in (b), and its waveform becomes like FIG. 7 (c). In FIG. 7C, the vertical axis,
The horizontal axis is an arbitrary unit.

[0012] When performing partial line selection, in order to suppress the frame response of the liquid crystal panel, preferably to be energized dispersed in one display cycle. Specifically, for example, after the first element of the vector (v) for the first simultaneously selected row electrode group (hereinafter, referred to as a subgroup) is applied, the second The first element of the vector (v) for the simultaneously selected row electrode group is applied, and so on.

Therefore, the voltage pulse sequence actually applied to the column electrodes determines how the voltage pulses are dispersed within one display cycle, and what selection matrix for each of the simultaneously selected row electrode groups. It is determined by whether (A) is selected. Therefore, the MLS driving how, in fact, a row electrode will be described below or sequence of voltage pulses applied to the column electrode looks like.

[0014] When simultaneously selecting a part of the total row electrodes (partial line selection) There are basically three schemes in terms of advance or selected pulse sequence at any time. The first scheme advances the row electrode selection pulse sequence by one when one subgroup is selected and the next subgroup is selected . That is, the selection pulse sequence is performed in units of subgroups . The second scheme advances the selection pulse sequence when all lines have been selected (for all subgroups) . The third method is
An intermediate scheme of the first method and the second method. The first of those formula
If it and the second towards expression, comprising a vector indicating the selected pulse as the number 1 to that shown in each subgroup. Here, each column vector of the selection matrix (A) is represented by A ₁ , A _2.
A _M and the number of subgroups were N _s .

[0015]

(Equation 1)

The sequence of voltages applied to the column electrodes is:
The column electrode voltage levels in the same manner as shown in FIG. 4 (b) vector _{(v) = (v 1,} v 2, v 3, ··) When expressed, in the case of the first method, (v _{1, v 2, v 3,} ··
, V ₁ , v ₂ , v ₃ ,..., And in the case of the second method , (v ₁ , v ₁ ,... V ₁ , v ₂ , v ₂ ,.
v ₂ , v ₃ ,...). Each iteration is the number of subgroups.

These relations can be generally expressed by a formula composed of a vector and a matrix as shown in Expression 2.

[0018]

(Equation 2)

The vector (x), vector (y), and matrix (S) are as follows. The column electrode display pattern vector (x) = (x ₁ , x ₂ ,..., X _M ) has the same number of elements as the number M of row electrodes, and corresponds to a display pattern corresponding to a row electrode on a specific column electrode. Is an element. Here, it is assumed that the case of off is 1 and the case of on is -1. Column electrode voltage sequence vector (y) = (y ₁ , y ₂ ,..., Y
_N ) has the same number of elements as the number N of pulses applied in one display cycle, and the voltage level for a specific column electrode is arranged in time series in one display cycle as an element.

The row electrode pulse sequence matrix (S) is M
A matrix of N rows and N columns, in which column vectors composed of row electrode voltage levels for a specific column electrode are arranged in time series within one display cycle as elements. The element corresponding to the unselected row electrode is set to 0. For example, the row electrode pulse sequence matrix S in the first scheme is written as the number 3 by the column vector A _i, and zero vector Z _e of the selection matrix A.

[0021]

(Equation 3)

As described above, in S, all the column vectors of the selection matrix exist once for each subgroup, and thereby, the effective voltage values for all the pixels are determined. That is, the display is determined by completing the sequence of S. This period is one display cycle.

[0023] In view of the conventional MLS driving how, it was unique two problems respect to its display quality. No.
1 challenge is that at the same time non-uniformity of display occurs between the line to be selected, resulting in unevenness between fine lines in the row electrode direction. The second problem is that Viewing uniformity of had an image (pattern) dependent. That is, since the data voltage waveform applied to the column electrode is determined by the calculation of the image information and the selection matrix A, a uniform display without crosstalk can be obtained in an image, but the crosstalk is conspicuous in an image. It is.

[0024]

We have studied a new driving method to solve the above problems, and have driven a liquid crystal panel by a method of simultaneously selecting a plurality of lines to obtain a uniform display with almost no display unevenness. Specifically, according to the present invention, a row electrode of an image display device having a plurality of row electrodes and a plurality of column electrodes is L
A method for driving an image display device, comprising selecting (L ≧ 3) all at once and applying a selection signal based on a column vector of an orthogonal selection matrix (A) in which row vectors of L rows and K columns are orthogonal to row electrodes. , Two or more different selection matrices (A ₁ , A ₂ ,
.., A _x ) are used, and an orthogonal matrix (B) of L rows (K _× X) columns (B) = (A ₁ ) sequentially arranged in the order in which they are used.
A ₂ ... A _x ) is a row voltage sequence vector (Z) _i , (Z) _j (i, j is a matrix) in which the continuous lengths of positive and negative elements of any two row vectors of the matrix (B) are elements. Vector lengths R _i , R _{j of the} matrix (B)
And the maximum value R _{max of} R _i (i = 1 to L) is | R _i −R _j | / R _max ≦ 0.3 (i, j = 1 to L)
To provide a driving method of an image display device characterized by meet the relation of L).

[0025], (Z) the maximum value of _j of the element Z _{0, j} and Z
_0, the relationship between the maximum value Z _max of j (j = 1~L) is 0.6
≦ Z _0, provides a driving method of the _{j / Z max ≦ 1 (j} = 1~L) above image display apparatus according to claim full plus that the relationship.

Also, a column electrode display pattern vector (x) having a display pattern (OFF = 1, ON = -1) corresponding to a row electrode located on a specific column electrode and selected at the same time.
= (X ₁ , x ₂ ,..., X _M ) and a column electrode voltage sequence vector whose elements are the voltage levels for the column electrodes arranged in time series within one display cycle consisting of N voltage pulses. (Y) = (y ₁ , y ₂ ,..., Y _N )
And a column consisting of row electrode voltage levels for a particular column electrode
Vectors must be arranged in chronological order within one display cycle.
And the element corresponding to the unselected row electrode is set to 0.
Row electrode pulse sequence matrix (S) which is a matrix of rows N columns
And (y ₁ , y ₂ ,..., Y _N ) = (x
₁ , x ₂ ,..., X _M ) (S), and Δy _i = |
If y _i −y _i−1 | (i = 2 to N), (x) =
The driving method of the image display device described above , wherein Δy _i <0.7 · L with respect to (1, 1,..., 1) is provided.

Further, (x) = (1, 1,..., 1)
, The column electrode voltages y _j−1 , y _j and L
DOO _{is, | y j-1 | <} 0.5 · L and | y _j | <0.
5 · L (j-1 and j are suffixes indicating immediately before and after the polarity inversion, respectively) is provided.

In the present specification, unless otherwise specified, L is used as the number of simultaneously selected row electrodes, K is used as the number of columns in a selection matrix, M is used as the number of all row electrodes, and N is used in one display cycle. Is used as the number of pulses applied to. In the present invention, the number of simultaneously selected row electrodes is preferably L ≧ 3.
And particularly preferably L ≧ 5.

The present inventors have studied the causes of the above-mentioned display unevenness when a plurality of items are selected simultaneously. As a result, the present inventors have newly obtained the following knowledge and greatly reduced the display unevenness by satisfying a specific condition. It was found Rukoto can decline to.

The first of the findings is as follows.
That is, in the MLS driving method , the variation of the frequency component for each line causes display unevenness. When L row electrodes are selected at the same time, pulse voltages having different polarities must be applied to the row electrodes in order to simultaneously and independently control the display pattern in the column direction. This is a natural consequence of the fact that the selection matrix (A) has the orthogonality of the row vector, and the Hadamard matrix described above is a typical example. Therefore, the drive waveform frequency component usually differs for each line.

This is a feature different from the line sequential driving method . That is, in the line-sequential driving method , although the frequency component of the waveform applied to the row electrode is not different for each row electrode, the MLS
In the driving method , the frequency components of the waveform applied by the row electrodes are usually different. Therefore, in the MLS driving method ,
Display unevenness between fine lines occurs.

[0032] Specific examples of the variation of the frequency component of the driving waveform of each row electrodes as shown in FIG. 2, field 3 rows and 4 columns of the selection matrix
The present invention will be described with respect to the case . Elements corresponding to each row of the matrix are sequentially applied to each row electrode as a selection pulse.
If sequence in matrix as shown in FIG. Is Ri returned Repetitive, positive or negative that a repetitive pattern of the selection pulse in each row electrode is different. In other words, the frequency is different for each line with respect to the inversion of the polarity of the selection pulse. In the example shown in the figure, the polarity of the selection pulse is inverted every time in the line corresponding to the first row, but is inverted every two times in the second and third rows. Therefore, the frequency of the first row is twice as high as that of the second and third rows. For this reason, the second and third rows are driven with more low frequency components than the first row.

In general, since the magnitude of the waveform distortion and the threshold characteristic of the liquid crystal depend on the frequency, the line 1 has a few lines.
In comparison, the black in the negative display becomes high threshold value characteristic (off,
If it is on (white), it will appear darker than the other lines.

The second finding is as follows.
That is, in the MLS driving method , the fluctuation width of the column electrode voltage for each pulse strongly affects the fluctuation of the effective value of the column electrode waveform. This is also a feature different from the line sequential driving method ,
It is considered that the MLS driving method is caused by a higher column electrode voltage level than the line sequential driving method . That is, in the line-sequential driving method , a large waveform distortion mainly occurs at the time of polarity reversal, but in the MLS driving method, it can also occur when the fluctuation width of the column electrode voltage for each pulse is large. Therefore, ML
In the S drive method , the column electrode voltage may frequently fluctuate depending on the type of the selection matrix, and strong crosstalk is likely to occur.

This point will be specifically described. The voltage waveform applied to the liquid crystal is determined by the row voltage waveform and the column voltage waveform. However, since the column voltage waveform depends on the display pattern of the column, there are cases where the voltage fluctuation of the column voltage is large and small. Selection matrix shown in FIG. 3, the image information at a certain column in the case of all off or all-on, in which the voltage variation can suppression. This matrix is (x) = (1,1,1,.
., 1), the maximum fluctuation width Δ of the column voltage sequence
y is 2, and the fluctuation of the column electrode voltage is relatively small. However, a special pattern, for example, (x) = (1,1,
For (1, -1, -1, 1, 1, 1), Δy is 8, resulting in large column electrode voltage fluctuations.

The main object of the present invention is to reduce the display unevenness between the MLS driving how <br/> unique simultaneous selection lines, both of the image pattern dependence of the display uniformity. Uniform images over to any conventional STN driving how Achieving this point can provide.

[0037] In order to improve both at the same time, in the present invention, different two or more selected択行column was Rikae <br/> Repetitive alternately used. Specifically, after the selection voltage sequence is applied which is determined by the S, S used 'by applying a selection voltage sequence determined by a method (S → S of returning Ri Repetitive this application' → S → S '). Use are the matrix is not limited to two, may be used Repetitive <br/>-back three or more kinds. As S ′, one in which the rows of S are replaced, one in which the columns are replaced, or a completely different function system can be used.

In this case, the problem that one display cycle becomes longer does not occur in this case. This is because the effective voltage value of each pixel is determined in a time series (cycle) in one matrix. In this way, the uniformity of each row line can be increased by using a plurality of different matrices alternately,
An image with high uniformity can be provided.

Further, by using repeatedly different two or more selection択行columns alternately, can be suppressed that the display uniformity is changed the display patterns. For one selection matrix, there is always a display pattern in which the voltage change in the voltage sequence to the column electrodes is large,
Using different selection matrices of more than one kind can prevent a situation in which display uniformity is impaired for a specific display pattern. That is, that Do allow less uniform display of pattern dependency.

Therefore, it is highly desirable to use a plurality of different selection matrices alternately to determine the row voltage sequence in terms of both display uniformity between lines and display uniformity between display patterns. it can.

[0041] In the present invention, as one characterized by further providing a frequency uniformity sequence itself line voltage. That is, in each row vector of the selected matrix, positive selection (1) or uniform negative selection a number (-1) are continuous (sequence for code) for each row
I do .

In the present invention, the frequency variation of the row voltage sequence
AbouttwoUse two criteria.First criterion
IsEach differentTwo or moreSelectionSelection matrix (A₁ , A_Two ,
・ ・ 、 A_x ) Are used in the order in which they are used.
L-row (K · X) -column orthogonal matrix (B) =
(A₁ A_Two ・ ・ A_x), Any of the matrix (B)
Let the continuous length of the positive and negative elements of two row vectors be the element
Row voltage sequence vector (Z)_i , (Z)_j (I,
j represents the i-th row and the j-th row, respectively)
R_i , R_j And R_i (I = 1 to L) is R
_max "| R_i -R_j | / R_max "
You. Second criterionIs (Z)_j The maximum value of the element_{0, j} When
Then Z_{0, j} The maximum value of (j = 1 to L) is Z_max And
The "Z_{0, j} / Z_max ".

[0043] will be described these criteria. First, a matrix group and its sequence are determined from the following viewpoints. When a plurality of different matrices are used successively, the period is defined as one period, and the positive / negative series of selection pulses in each row (each line) during that period is represented by the number of pulses. For example, (++ −−− ++++ −
In Repetitive returns series of +), and (3331). Sequentially parallel-solid vector number of consecutive symbols of the thus selected pulse to the row voltage sequence vector (Z) and call Bukoto. Here, the last + is continuous with the first + ,
The number of pulses is three.

The first criterion “| R _i −R _j | / R _max ” is considered to be a criterion indicating the degree of equalization of the average frequency of the row voltage. This is the row voltage sequence vector (Z)
Is an index of whether or not the number of elements is substantially the same between each line. In other words, it is an index of whether the number of positive and negative changes of the selection pulse is substantially the same.

In the present invention, the selection matrix is L rows and K columns,
Within one period (one display cycle × the number of types of selection matrices to be used), the number of times R _i (ie, the number of elements of the row voltage sequence vector) in which the sign of the selection pulse in the simultaneously selected lines (the number L) changes. However, it is desirable that the condition of Expression (1) is satisfied. More preferably, the condition of equation (1 ′) and
Is done.

[0046]

(Equation 4)

[0047]

[0048]

Under this condition, since the frequency components of the selection pulses in each row are substantially the same , display unevenness between lines is reduced.

The second criterion "Z _{0, j} / Z _max " is an index as to whether or not the lowest frequency of the selection pulse in each row is substantially the same. In other words, it is an index of whether there is a large variation in the size of the element of (Z). In particular, it is not desirable to include an extremely low frequency component.

In the present invention, when the maximum value of the element of the vector (Z) in the J-th row is Z _{0, j} , the maximum value Z _max
On the other hand, it is desirable to satisfy the condition of Expression (2) . Than
Desirably, the condition of Expression (2 ′) is satisfied.

[0052]

(Equation 5)

[0053]

[0054]

Under this condition, since the lowest frequency of the selection pulse in each row is substantially the same , display unevenness between lines is reduced.

[0056] Thus, the above equation (1), the condition of equation (2), respectively, of the row voltage waveform is a condition relating to the minimum frequency and the average frequency (frequency dispersion). These are used according to the required level of uniformity, but when high uniformity is required, it is most desirable to satisfy both at the same time.

A specific example will be described with reference to FIG. When the selection matrices A ₁ and A ₂ shown in FIG. 1 are used alternately,
The vectors (Z) _i for each row are the four types shown in the figure. Since the vector length are all 4, R _i regardless of i, are all 4, therefore, R _max is four. On the other hand, Z _{0, j} which is the maximum of the elements of the vector (Z) _i
Are 4, 3, 4, and 3, respectively, so that Z _max is 4
Becomes As described above, in the sequence shown in FIG.
_i− R _j | / R _max = 0 and Z _{0, j} / Z _max = 3 /
4 or because is 1, the above equation (1), equation (2) not only formula (1 ') are satisfied also formula (2').

As a conventionally known selection matrix, there is a pseudo-random matrix in which frequency components between lines are made uniform.

However, in the pseudo random matrix, the number of selection pulses K in one display cycle is L
² -1, and the need of very long sequence with an increase of the L. Prolonging the display cycle is not desirable because it causes display unevenness and flicker due to frequency unevenness of the liquid crystal characteristics.

As described above, the pseudo-random matrix has many problems, but also has the advantage that the frequency components of each selected row are substantially equal. That is , it is effective in eliminating the difference between the lines and performing uniform display between the lines. The present inventors utilizing the features of this pseudo-random matrix, and, considering a driving how to overcome the above problems,
Orthogonality of the row vectors, cycle length, it was found driving how that is effective against both in terms of the line between uniformity.

According to a preferred embodiment of the present invention,
The matrix (S) is evaluated by Expression 6 as a criterion for selecting an optimal column waveform from the viewpoint of the maximum voltage fluctuation width on the time axis (in the order in which the sequence proceeds).

[0062]

(Equation 6)

At this time, it is preferable to suppress Δy _i to a certain value or less for all display patterns.
This is practically difficult because y _i is a value that depends on the column electrode display pattern vector (x). For example, the value of Δy _i is completely different between the display of all-on and the display of the checkered pattern.

In a preferred embodiment of the present invention, the column electrode display pattern vector (x) serving as a reference is (x)
= (1,1, ..., 1). The present inventors have studied, the pattern most crosstalk is noticeable in normal use, the all-on or a state close to full off (for example, that on a uniform solid pattern, there are displayed the block or line ), And it was found that by suppressing the crosstalk in this state, the appearance of the entire display was significantly improved.

[0065] In general, by the Δy _i <0.7 · L, can suppression to the extent practicable the maximum voltage variation difference.
Particularly preferably, Δy _i ≦ 0.5 · L. By doing so, it becomes possible to make the frequency components of each line substantially equal, reduce the pattern dependence, and suppress the magnitude of crosstalk without lengthening the display cycle.

In a further preferred embodiment of the present invention,
An object of the present invention is to reduce display unevenness by performing polarity inversion of an applied voltage at an appropriate timing. That is, by inverting the polarity at a predetermined cycle, not only can the DC component be removed even if any orthogonal matrix is used as the selection matrix, but also by adjusting the cycle of the polarity inversion, the driving waveform the frequency band of central control as possible out of control. If the frequency band is too low, display unevenness or flicker may occur depending on the display pattern, but such inconvenience can be eliminated by reversing the polarity. In this sense, polarity inversion is extremely effective when the driving frequency is relatively low.

As the timing of performing the polarity inversion, when the level is closer to 0 in the column voltage sequence,
It is highly desirable to perform the inversion. This is to suppress the effective value fluctuation due to the waveform distortion due to the polarity inversion as much as possible. Specifically, it is desirable that the column electrode voltage levels y _j−1 and y _j before and after the timing of the polarity inversion satisfy the following relationship with the number L of the simultaneously selected rows.

| Y _j-1 | <0.5 · L and | y _j |
<0.5 · L (j-1 and j are suffixes indicating immediately before and after the polarity inversion, respectively) The above relationship is more desirably expressed as follows.

| Y _j-1 | <0.3 · L and | y _j |
<0.3 · L (j-1 and j are suffixes indicating immediately before and after the polarity inversion, respectively) When this condition is satisfied, the influence of the polarity inversion on the effective value can be suppressed as much as possible.

The difference between the column voltage levels before and after the polarity inversion is | y _j-1 -y _j | <0.7 · L, preferably | y _j-1 -y _j | ≦ 0. It is desirable to satisfy the relationship of 5 · L at the same time. This reduces both column voltage distortion at the time of polarity inversion and column voltage distortion at the time of column voltage fluctuation, and can greatly contribute to eliminating display unevenness. The implementation of the selective and appropriate polarity inversion selected and their sequence of Matrix Group (sequence), crosstalk, display unevenness between the lines, can simultaneously improve any of pattern dependence, obtain a very uniform display be able to.

The driving method according to the present invention is disclosed in
7907, Ru can be realized by using a circuit as described in USP5262881.

[0072] showed a block diagram of an example of a configuration of the circuit in FIG. This is a circuit for displaying 16 gradations for each of RGB. Data signal, 16-level signal MSB
To the LSB as a 4-bit signal. The data pre-processing circuit 1 has a column signal generation circuit 2 with a format and timing suitable for forming a column signal in the subsequent stage
Is a circuit for outputting a data signal input to the.
The data signal output from the data preprocessing circuit 2 and the orthogonal function signal output from the orthogonal function generation circuit 5 are input to the column signal generation circuit 2.

[0073] column signal generating circuit 2 after forming a column signal I row a predetermined calculation using the two signals, and outputs to the column driver 3. The column driver 3 forms a column electrode voltage to be applied to a column electrode of the liquid crystal panel 6 from an input column signal using a predetermined reference voltage, and outputs the column electrode voltage to the liquid crystal panel 6. On the other hand, a row electrode voltage obtained by converting the orthogonal function signal output from the orthogonal function generation circuit 5 by the row driver 4 is applied to the row electrodes of the liquid crystal panel 6. These circuits are provided with a timing circuit and the like as needed, and operate at a predetermined timing.

The orthogonal function used in the present invention is generated by the orthogonal function generating circuit 5. Orthogonal function generating circuit 5 may also be row I signal forming operations on every orthogonal function signal generator. However, it is preferable in terms of simplicity that the orthogonal function signal to be used is stored in the ROM in advance and read out at an appropriate timing. That is, pulses that define the timing of voltage application to the liquid crystal panel 6 are counted, and the orthogonal function signals in the ROM are sequentially read using the counted value as an address signal.

The data preprocessing circuit 1 is described in detail in FIG.
The configuration is as follows. The signal processing is performed with 4
Bit image data is divided into four sets of R, G, and B bits, each of which is performed in four sets. That is, MSB (2 ³ ), 2nd MSB
(2 ² ), 3rdMSB (2 ¹ ), LSB (2 ⁰ ) 4
The signals are divided into sets and parallel processing is performed.

5 bits at 3 bits per input dot
Tsu preparative worth of data is sent to the memory 12 is converted by 5-stage serial-to-parallel converter 11 into 15-bit data. Specifically, 5
Serial data is input to the input terminal of the stage shift register, and the output of each of the five taps is input to the memory 12.

As the memory 12, a VRAM having a data width of 16 bits was used. Writing to the memory 12 is performed as follows using the direct access mode. That is, the data on the row electrodes corresponding to the same column electrode is stored in seven adjacent addresses for the seven row electrodes selected simultaneously. By doing so, reading from the memory at the subsequent stage can be performed at high speed, and the calculation becomes easy.

Reading from the memory 12 is performed in a high-speed sequential access mode according to the driving timing of the liquid crystal display device , and four sets of 15-bit data are sent to the data format conversion circuit 16.

The data format conversion circuit 16 converts the data sent in parallel with a 15-bit width for each gradation into RGB.
This is a circuit that rearranges the signals into parallel signals having a 20-bit width, and it is usually sufficient to provide appropriate wiring on a circuit board.

In the data format conversion circuit 16 , RG
After being converted into B3 sets of 20-bit data, the data is sent to the gradation determining circuit 15. In the gradation determination circuit 15, 1
This is a frame modulation circuit that converts 4-bit grayscale data per dot into 1-bit on / off data to generate a sub-screen video signal, and realizes grayscale display of the sub-screen in, for example, 15 cycles. Specifically, a demultiplexer that distributes 20-bit width data to 5-bit width data at a predetermined timing was used. Which bit corresponds to which sub-screen is determined by counting by the frame counter. In this way, 20-bit data corresponding to 5-dot gradation data is converted into 5-bit serial data without gradation and output to the vertical / horizontal conversion circuit 13.

The vertical / horizontal conversion circuit 13 is a circuit for transferring and storing five pixels of display data seven times, and reading out the data five times as seven pixel data. 2 sets of 5x
It consists of a 7-bit register. Aspect conversion circuit 13
Is sent to the column signal generating circuit 2.

Column signal generating circuit 2 has the configuration shown in FIG. Exclusive OR gate 2 for 7-bit data signal
, 23,... Exclusive OR gate 23
Are also input from the orthogonal function generator 5. The output of the exclusive OR gate 23 is added to the row electrodes selected simultaneously by the adder 21.

The column driver 3 has a configuration as shown in FIG. Shift register 31, a latch 32, which is a de <br/> code Da 3 3, and a voltage divider 34. A demultiplexer is used as the voltage level selector 33,
When one row of data is sent to the shift register 31, the display data is converted into a column voltage.

The row driver 4 has a configuration as shown in FIG. Driving pattern register 41, it consists of a selection signal register 42, and decoders 4 3. The simultaneously selected row is determined by the contents of the selection signal register 42,
The polarity of the selection signal to be output to each row selected according to the contents of the driving pattern register 41 is determined. 0V is output to the non-selected rows.

[0085] FIGS. 8 to 12, is shown as an example of the circuit, unless and lose the essence of the present invention, Ru can adopt various circuit.

[0086]

EXAMPLES Using the circuits shown in FIGS. 8 to 12, the liquid Akirapa <br/> panel 6 is driven in the following manner. Liquid Akirapa channel number VGA module (pixel of 9.4 inches 480 × 240 × 3
(RGB)). Response time of the liquid Akirapa channel is 60msec in average of the rise and fall times. As described below, together with the simultaneously selected three row, the selection of each sub-group, to drive the columns of the selection matrix in one advancing system (first method).
Since the two-screen drive (up and down division) was performed, the number of subgroups was 35. The bias is adjusted so that the contrast ratio becomes almost maximum, and the contrast ratio of the display is 30:
1. The maximum luminance was 100 cd / m ² .

As shown in FIG. 4 (a), driving was performed using a selection matrix of 3 rows and 4 columns and the number of simultaneous selections L = 3. FIG.
In (a), 3 rows of a 4 × 4 Hadamard matrix are used, and 2
The cycle is the display cycle. The matrix was set such that the selection matrix (A) was followed by its inversion matrix. Line voltage sequence vectors representing the positive and negative sequence line voltage (selection pulse voltage) is as shown in FIG. 4 (a),
In the first and third rows, the maximum element Z _{0, j} = 2 when the number of positive and negative changes R _i = 6, and in the second row, the maximum element Z _{o, j} = 4 when R _i = 2.
It is. When all ON display was performed by this driving, the line for the second line became a bright line, and the uniformity of the whole was impaired.

Hereinafter, examples of respective matrices having different sizes as shown in FIGS. 1, 4, 5 and 6 will be described. In Table 1, condition (1): maximum difference between rows | R _i -R _{j of the} number of positive / negative inversions of the row voltage
| / R _max , condition (2): maximum ratio Z _{0, j} / Z _max between rows of the longest period of the row voltage, condition (3): maximum displacement of column voltage (Δy _i <0.7 · L When satisfied: Y, when not satisfied: N). Here, each evaluation was in the order of A: good to C: bad.

In particular, when the driving was performed with the polarity of the row selection voltage and the column voltage inverted each time the 32 subgroups were selected under the driving conditions shown in FIG. 6C, crosstalk, line unevenness, etc., occurred in almost all images. The level was almost invisible, and a very uniform display was obtained.

[0090]

[Table 1]

[0091]

According to the present invention, MLS driving method odor <br/> Te, using two or more different selection択行columns respectively, row voltage sequence vector _{(Z) i, (Z)} j (i, j is Vector lengths R _i , R _j and R _i
And a maximum value R _max of the (i = 1~L), the _{relation, | R i -R j | /} R max ≦ 0.3 (i, j = 1~L) to substantially fill the relation So between the lines
, And variations in display uniformity depending on the display pattern can be suppressed, and a high-quality display can be obtained. Further, the frequency component does not become too low.

[0092] Also, (Z) the maximum value of _j elements Z _{0, j} and Z
_0, the relationship between the maximum value Z _max of j (j = 1~L) is, so that substantially satisfy the relationship of _{0.6 ≦ Z 0, j / Z} max ≦ 1 (j = 1~L) By doing so,
It is possible to suppress display unevenness between lines and obtain high-quality display.

If Δy _i = | y _i -y _i-1 | (i = 2 to N), then (x) = (1, 1,..., 1), substantially Δy _i <to ensure that the 0.7 · L, by, since the all-on or cross-talk is likely the most noticeable can suppression the cross-talk in the display close to the all off,
The appearance of the display can be improved as a whole.

Further, (x) = (1, 1,..., 1)
, The column electrode voltages y _j−1 , y _j and L
Is substantially | y _j-1 | <0.5 · L and | y _j | <0.5 · L
(J-1 and j are suffixes indicating immediately before and immediately after the polarity inversion, respectively), thereby eliminating display unevenness caused by a low frequency component and suppressing crosstalk caused by the polarity inversion. Thus, a display with extremely high display uniformity can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a row selection sequence in a driving method according to the present invention.

[2] (a), explanation diagram for explaining a variation of the frequency components of (b) row selection 択Pa Angeles.

FIG. 3 is an explanatory diagram illustrating display pattern dependence of display uniformity.

FIGS. 4A to 4D are explanatory diagrams illustrating various row selection sequences.

FIGS. 5A and 5B are explanatory diagrams illustrating various row selection sequences.

FIGS. 6A to 6C are explanatory diagrams illustrating various row selection sequences.

7 (a) ~ (c) are conceptual views and waveform diagrams for explaining a method of applying a voltage in MLS driving how.

FIG. 8 is a block diagram illustrating an example of a configuration of a circuit for implementing the present invention.

9 is a block diagram illustrating a data pre-processing circuitry.

FIG. 10 is a block diagram showing a column signal generation circuit.

FIG. 11 is a block diagram showing the column driver.

12 is a block diagram showing a row driver.

[Explanation of symbols]

 1: data preprocessing circuit 2: column signal generation circuit 3: column driver 4: row driver 5: orthogonal function generation circuit 6: liquid crystal panel

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Makoto Nagai 1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Central Research Laboratory (72) Inventor Takeshi Kuwata 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Asahi Glass Co., Ltd. Central Research Laboratory (56) References JP-A-5-46127 (JP, A) JP-A-5-100642 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G09G 3/00 -3/38 G02F 1/133 505-580

Claims (4)

(57) [Claims] An image display device having a plurality of row electrodes and a plurality of column electrodes is collectively selected as L (L ≧ 3).
A method for driving an image display device in which a selection signal based on a column vector of an orthogonal selection matrix (A) in which row vectors of L rows and K columns are orthogonal to each other is applied to a row electrode, wherein two or more different selection matrices (A ₁ , A ₂ ,
, A _x ) are used, and an orthogonal matrix (B) of L rows (K · X) columns (B) = (A ₁ ) sequentially arranged in the order in which they are used.
A ₂ ... A _x ) is a row voltage sequence vector (Z) whose elements are the continuous lengths of the positive and negative elements of any two row vectors of the matrix (B).
_i , (Z) _j (i and j are i rows and j of the matrix (B), respectively)
Row lengths R _i , R _j , and R _i (i = 1 to
And a maximum value R _max of L), the _{relation, | R i -R j | /} R max ≦ 0.3 (i, image display apparatus, characterized in that meet the relationship of j = 1 to L) Drive method. 2. The maximum values Z _{0, j} and Z _{0, j of} (Z) _j elements
Claim relationship between the maximum value Z _max of the (j = 1 to L), characterized in _{0.6 ≦ Z 0, j / Z} max ≦ 1 (j = 1~L) relationship full plus that of 2. The driving method of the image display device according to 1. 3. A display pattern (off is 1, on is -1) corresponding to a row electrode which is located on a specific column electrode and selected at the same time.
Column electrode display pattern vector (x) = (x
_{1, x 2, ···, x} M) and the column electrode voltage sequence vectors to a voltage level element relative to the column electrodes are arranged in time series within one display cycle of N voltage pulses (y) = (Y ₁ , y ₂ ,..., Y _N ) and the column vector consisting of the row electrode voltage level for a particular column electrode
Elements are arranged in chronological order within one display cycle.
The element corresponding to the non-selected row electrode is set to 0 and the M row N
A row electrode pulse sequence matrix (S), which is a matrix of columns;
Is (y ₁ , y ₂ ,..., Y _N ) = (x ₁ , x ₂ ,...)
., X _M ) (S), and Δy _i = | y _i -y _i-1 | (i = 2 to N), where (x) = (1, 1,..., 1) , Δ y _i <0.
3. The driving method for an image display device according to claim 1, wherein the value is 7 · L. (4) For (x) = (1, 1,..., 1),
The column electrode voltages y _j−1 , y _j and L before and after the polarity inversion are: | y _j−1 | <0.5 · L and | y _j | <0.5 · L
(J-1, j is immediately before each polarity reversal, subscript indicating the immediately) driving method of an image display apparatus according to claim 1, 2 or 3, characterized in that satisfies.