JPH1073832A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the satisfactory display of a large panel. SOLUTION: In a liquid crystal display device in which column electrodes 106 connected to a column output circuit 103 and row electrodes 105 connected to a row output circuit 104 are provided in a matrix shape, row electrodes 105a, 105b of 1-240 lines are arranged by being divided in a display screen into the left and the right and divided positions of the divided row electrodes are arranged in a comb-teeth shape. Thus, driving waveforms are uniformaized to make a display beautiful.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device using a passive matrix drive display. Among them, the present invention relates to an STN type liquid crystal display device, and particularly to a liquid crystal display device having a row electrode which is long in a lateral direction of a display screen.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show a simple structure of a conventional STN type liquid crystal panel. 240 dots vertical, 6 horizontal
It has a screen size of 40 dots. In this case, the number of row electrode lines serving as scanning lines of the liquid crystal panel 100 is 240, and the number of column electrode lines is 640.

In the configuration shown in FIG. 4, 240 row electrode lines are driven by two row driver ICs 102 for driving two row electrodes. Each of the row driver ICs 102 has one
It has 20 drive outputs. Also, a case is shown in which eight column electrode driving column driver ICs 101 are used to drive 640 columns, which is the total number of columns, for the column electrodes. Therefore, each column driver has 80 drive outputs and drives all column electrodes.

FIG. 5 illustrates FIG. 4 in more detail, in which two row driver ICs 102 are connected to the output circuit 10.
4 are connected to the respective row electrode lines 105 and driven. On the other hand, eight column driver ICs 101
Shows a configuration in which the connected column electrode lines 106 are driven by the built-in output circuit 103.

[0005]

The prior art liquid crystal display device having the structure described with reference to FIGS. 4 and 5 has the following problems. In other words, as long as a liquid crystal panel having a small shape and a display portion close to a square is adopted, no major problem was found. However, in a liquid crystal display device having an extremely long screen in the horizontal direction used for an automobile or the like,
The row electrode line 105 has a relatively longer structure than the length of the column electrode line 106 in FIG.

Further, as the display screen becomes landscape-oriented, the width of the column electrode lines 106 increases accordingly, and as a result, the electric resistance of the column electrode lines 106 decreases. It will be long and have a large electric resistance value. At this time, the panel 100
When the driving voltage waveform (hereinafter, simply referred to as a waveform) of the column electrode line 106 in FIG.
The waveform applied from the output circuit 103 of C101 does not change much.

On the other hand, as shown in FIG. 6, the waveform applied to the row electrode line 105 is largely distorted.
In other words, it can be said that the signal has been delayed. Reference numeral 110 in FIG. 6 is a waveform to be originally applied, and a broken line curve of reference numeral 111 indicates a waveform when a certain point on a long row electrode line is monitored.

Further, V _DD , V ₁ , V ₂ , V ₃ , V ₄ , V ₅
Indicates the liquid crystal power supply potential. This blunted waveform means that the effective value voltage for determining the lighting (on) and non-lighting (off) of the liquid crystal has shifted backward, and as a result, the ghost phenomenon shown in FIG. generate.

(N-1), (n),... (N +
4) shows a row electrode line 105, and (m-1),
(M), (m + 1),... (M + 5) are column electrode lines 10
6 is shown. Also, ghost display is indicated by hatching separately from the original display data (the black square portion). In addition, when the normal line sequential driving is used, the ghost display is generated on the upper side of the screen due to the blunted waveform of the row electrode line.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a first aspect of the present invention is a liquid crystal display device having a plurality of column electrodes and a plurality of row electrodes provided in a matrix. Provided is a liquid crystal display device characterized in that at least two or more row electrodes are divided into left and right parts on a display surface, and the divided positions of the divided row electrodes are different.

According to a second aspect of the present invention, there is provided the liquid crystal display device according to the first aspect, wherein one of the divided row electrodes and the other are connected to respective driving circuits.

According to a third aspect of the present invention, there is provided the liquid crystal display device according to the first or second aspect, wherein the divided ends of the divided row electrodes are arranged substantially in a comb shape.

According to a fourth aspect of the present invention, a plurality of row electrodes driven simultaneously from both sides of the display surface using a driving method of a simultaneous selection method of plural lines are used, and the row electrodes selected simultaneously have the same length. The liquid crystal display device according to claim 1, 2 or 3 is provided.

According to a fifth aspect of the present invention, there is provided the liquid crystal display device according to the fourth aspect, wherein the simultaneously selected row electrodes have the same number of pixels.

A preferred embodiment of the present invention further comprises the following configuration. (1) The row electrode wire is divided near the center. (2) The divided row electrode lines are driven from both sides by respective row driver ICs. (3) Divided part when dividing the row electrode wire from the center (hereinafter
(Referred to as abutting parts) are not aligned vertically. (4) Driving method for simultaneously selecting a plurality of lines (ML
When the (A drive system) is adopted, a set of row electrode lines driven simultaneously is divided into the same length.

(5) The number of row electrodes is 200 or more, and the number of column electrodes is 600 or more. (6) The length in the row direction (vertical direction of the screen) is 4 cm or more, and the column direction is 12 cm.
Above. (6) The aspect ratio of the screen is such that length of row electrode / length of column electrode ≧ 1.5.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention operates as follows and contributes to the improvement of the display characteristics of a liquid crystal display device. (I)
By dividing the row electrode line into two, the load of the row electrode line is reduced by half, and the waveform applied to the row electrode line is suppressed. (B) When one undivided row electrode line is driven on both sides, collision of different potentials occurs due to the difference due to the delay of the output circuits of the left and right row driver ICs that drive this row electrode line. Since the row electrode lines are divided and arranged, an electrical short (a competition state between a plurality of output circuits generating different output potentials depending on timing) does not occur.

(C) Since the division of the row electrode lines is irregular, it is difficult to see the division lines. (D) Display ghosts can be almost completely eliminated. (E) It is more effective in the case of a driving method in which a plurality of row electrodes are selected at the same time.

[0019]

【Example】

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention. A liquid crystal panel of the same size having 240 vertical row electrode lines and 640 column electrode lines as in the configuration of FIG. 5 described above. Elements having the same function are denoted by the same reference numerals. Although the row electrode line 105 in FIG. 5 is formed as one continuous electrode line, in the present invention, the row electrode line is divided near the center of the panel, and the two row electrode lines 105a and 105b are distributed to the left and right. Was placed as

In FIG. 1, the uppermost row electrode line 105a is divided at the 320th column electrode line from the left, and the next (vertical) second row electrode line 105a is 3
It is divided by the eighteenth column electrode line. Hereinafter, each row electrode line is divided in the vicinity of the center of the display surface, and the remaining row electrodes 105b on the right side are divided into
Row driver IC 102 for driving the same type of row electrode
It is configured to be driven by.

The division position of the row electrode was set in the gap between the intersecting column electrodes. As the center position in the column direction (assumed to be 0), for each row electrode (No. 1 to 240), the number of column electrodes divided from the center position is indicated. 0, -2, +1, -1)
Was repeated. The minus sign means that the image is shifted to the left of the screen, and the plus sign means that the image is shifted to the right of the screen and divided.

With this configuration, the load C of one long row electrode wire 105 in the conventional example as shown in FIG. 5 has been reduced to about half. Further, the rounding of the waveform shown in FIG. 6 could be reduced. Therefore, the ghost phenomenon of the display shown in FIG. 7 could be suppressed. As a result, a beautiful display screen not found in the conventional example was obtained.

As described above, the row electrode dividing lines are not cut vertically and linearly from the center, but are irregularly (comb-shaped) as shown in FIG. It was possible to make it difficult to see the cuts resulting from the difference in luminance between the cut edges.

Comparative Example 1 FIG. 6 shows a case in which row driver ICs are provided on both sides of the liquid crystal display device having the structure shown in FIG. 5 and one long row electrode line 105 (not divided) is driven from both sides. The output waveform of the row driver IC 102 as shown in FIG. Therefore, every time the output potential of the output circuit 104 in the row driver IC 102 is switched, a problem occurs in that the output circuits temporarily collide through the connected (not divided) row electrode lines 105.

The collision time is 1 μs or less until the same output voltage is obtained. However, when the time for selecting one row electrode line is in the range of 20 to 30 μs, the display quality deteriorates and cannot be ignored. .

(Comparative Example 2) Row electrode wire 105 of Example 1
a, middle, 320th column electrode line 10 from the center
6 and all the row electrode lines 105a were aligned. As a result, the divided portion looked like one line in the vertical direction of the screen. This is because the effective voltage applied through the output circuit 104 incorporated in the row driver IC 102 shown in FIG.
a and the right 105b are slightly different.

It has been found that the main cause is caused by a difference in load due to a difference between the right column electrode data and the left column electrode data, a variation of the row driver IC 102, a resistance distribution of a printed circuit board, and the like.

(Comparative Example 3) FIG. 3 shows an STN-type liquid crystal display device having a well-known structure, in which the panel 100 is divided into two and vertically driven. In this, 240 row electrode lines and 640 column electrode lines are arranged on both the upper and lower sides. The upper and lower divisions are made in order to obtain a duty ratio margin related to the characteristics (contrast characteristics and the like) of the liquid crystal panel.

For this reason, the column electrode lines are divided in the middle of the screen in the vertical direction. May be seen as

In the case of this configuration, the divided portion 103 cannot be divided irregularly. This is based on the fact that the column driver 101 fetches and outputs data corresponding to arbitrary selected upper and lower row electrode lines, respectively. Therefore, there is a drawback that an unnecessary line appears in the middle of the screen.

(Embodiment 2) FIG. 2 shows Embodiment 2 of the present invention. 2, the same parts are denoted by the same reference numerals as in FIGS. 1 and 5.

The difference between the second embodiment shown in FIG. 2 and the first embodiment shown in FIG. 1 is that the second embodiment shows an example in which a plurality of row electrode lines are driven simultaneously (MLA driving method). FIG. 2 shows a case where two adjacent row electrode lines 105a and 105b are selectively driven at a time. Therefore, as shown in FIG. 2, the first and second row electrode lines 105a
The third column electrode line is divided at the 321st column electrode line, and the third and fourth lines are divided at the 321st column electrode line.

Using the notation described above, the division positions are (0, 0, +1, +1, -2, -2,... -1,-
1).

In the driving method based on the plural simultaneous selection, a result of an operation between a function such as a Hadamard function and data to be displayed is transmitted from the column driver IC 101 to the column electrode line 106.
To the row electrode line 105a selected at a time.
If the lengths of the drive circuits 105b are not uniform, the configuration of the drive circuit becomes extremely complicated, and it is difficult to realize even the current semiconductor technology, circuit technology, and mounting technology.

FIG. 2 shows a case where two specified sets are driven simultaneously. However, it is similarly possible to increase the number of three, four, and five driven simultaneously. At this time, the cuts of the row electrode lines are aligned and made easy to see as much as the number of selections is increased, but the positions of the vertical cuts arranged near the center are dispersed to adjust to the acceptable range of practical appearance did it.

[0036]

As described above, according to the present invention,
A clear screen without ghost display could be provided. In particular, with the recent increase in the size of the panel, the length of the row electrode wire has been increasing. In the first embodiment, the example of the column driver having 640 rows is shown.
Actually, since 1024 pixels are divided into three column electrode lines of R, G and B, 1024 × 3 = 307
Two column electrodes are required.

As a result, although the width of the electrode is reduced and the resistance of the column electrode line is increased, the row electrode line remains as one long shape and the load remains large. The present invention can provide a good display screen even for such a medium- to large-sized liquid crystal panel.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment.

FIG. 2 is a circuit configuration diagram according to a second embodiment.

FIG. 3 shows an example of a panel in which a screen is divided vertically (Comparative Example 3)
FIG.

FIG. 4 is a circuit configuration diagram showing a conventional example of a horizontally long liquid crystal display device.

FIG. 5 is a circuit configuration diagram showing a further specific example of FIG. 4;

FIG. 6 is a waveform chart in a row electrode line.

FIG. 7 is an explanatory diagram of a ghost phenomenon of display.

[Explanation of symbols]

 101: column driver IC 102: row driver IC 103: column output circuit 104: row output circuit 105, 105a, 105b: row electrode 106: column electrode

Claims (5)

[Claims] In a liquid crystal display device provided with a plurality of column electrodes and a plurality of row electrodes in a matrix, at least two or more row electrodes are arranged on the display surface so as to be divided into right and left and divided. A liquid crystal display device, wherein the division positions of the row electrodes are different. 2. One of the divided row electrodes and the other are connected to respective drive circuits.
Liquid crystal display device. 3. The liquid crystal display device according to claim 1, wherein the divided ends of the divided row electrodes are arranged substantially in a comb shape. 4. A method of driving a plurality of lines at the same time, wherein among row electrodes which are divided and driven from both sides of a display surface, simultaneously selected row electrodes have the same length. 4. The liquid crystal display device according to claim 1, 2 or 3. 5. The liquid crystal display device according to claim 4, wherein the simultaneously selected row electrodes have the same number of pixels.