JP3081888B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device, and more particularly, to a driving circuit of a liquid crystal display device.

(Prior Art) In recent years, many liquid crystal display devices have come to be used for display portions of personal word processors or personal computers, taking advantage of features such as small size, light weight, and low power consumption.

A liquid crystal display device is formed by sandwiching a liquid crystal composition between a pair of opposed transparent electrodes. In recent years, a demand for a high-definition and large display screen has been increased.

In order to meet such demands, liquid crystal display devices have been constructed by extending the electrode length and further increasing the number of electrodes.

(Problems to be Solved by the Invention) Incidentally, when the liquid crystal display device is configured by extending the electrode length and further increasing the number of electrodes as described above, the following unexpected problems have occurred.

That is, when the liquid crystal display device has the above-described configuration, the resistance value of the electrode becomes higher than in the related art, and in particular, it becomes difficult to apply a sufficient effective voltage to the pixel farthest from the drive voltage supply side. As a result, the liquid crystal display device cannot obtain good contrast characteristics.

Therefore, it is conceivable to use a low-resistance metal or the like in parallel with the electrode, but such a method is not preferable in terms of productivity or cost.

The present invention has been made in view of the above-described problems, and has as its object to provide a liquid crystal display device which can obtain a high definition, a large display area, and have excellent display characteristics.

[Structure of the Invention] (Means for Solving the Problems) In the liquid crystal display device of the present invention, a plurality of first electrodes each having one end connected to a first drive circuit unit for supplying a drive voltage, and one end being driven Connected to a second drive circuit for supplying a voltage,
A liquid crystal display device comprising a plurality of second electrodes arranged in a matrix with respect to a first electrode, wherein a first electrode crossing one end of the second electrode has a second electrode. A correction means is provided for correcting so as to supply a drive voltage having a smaller effective value than the first electrode crossing the other end of the electrode.

(Operation) The present inventors have conducted various studies to solve the above-described problems, and as a result, have found the following.

For example, FIG. 6 shows a drive voltage waveform applied to the pixels of a simple matrix type liquid crystal display device having 640 signal electrodes Xi, with the vertical axis representing the voltage and the horizontal axis representing the voltage application time. . The curve (a) in the figure is a pixel (X1, Yj) formed by a certain scanning electrode Yj and the first signal electrode X1 of the liquid crystal display device, and the curve (b) is a certain scanning electrode Yj and the 160th pixel. Of the pixel (X
160, Yj) and the curve (c) show a pixel (X640, Yj) formed by a certain scanning electrode Yi and the 640th signal electrode X640.

From FIG. 6, in proportion to the distance from the voltage supply side,
The waveform distortion of the driving voltage applied to each pixel increases,
It can be understood that the effective voltage applied to the liquid crystal layer becomes smaller as the pixel is farther from the voltage supply side, and therefore, the display properties are different between the voltage supply side and the opposite side.

Therefore, the present invention corrects waveform distortion that gradually increases on the electrode end side in proportion to the electrode resistance, and applies a different effective value to one of the electrodes arranged in a matrix in advance so as to apply a uniform effective voltage. A correction means to which a voltage is applied is provided.

By providing such a correction means, the voltage actually applied to the pixel becomes uniform over the entire surface of the liquid crystal display device, and the display defect that has conventionally occurred can be eliminated.

Such a correction means may be provided on at least one of the liquid crystal cell side and the drive circuit side, and is preferably provided on the drive circuit side. The method of providing the correction means on the drive circuit side of the liquid crystal display device can make the liquid crystal display device very inexpensive, and even if a defect occurs, it can be easily achieved only by replacing only the integrated circuit element of the drive circuit portion. Defects can be eliminated, and a high production yield can be ensured.

Example (First Example) Hereinafter, a liquid crystal display device according to an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a liquid crystal display device (1) according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of a liquid crystal cell (3) taken along line A-A 'in FIG. It is shown.

The liquid crystal cell (3) of the liquid crystal display device (1) has 160 signal electrodes Xi (i = 1, 2,...) Formed with an electrode width of 0.33 mm.
160) a first electrode substrate provided with (11) and a second electrode substrate provided with 400 scanning electrodes Yj (j = 1, 2,..., 400) (31) having the same electrode width. The electrodes (11) and (31) of (41) are opposed to each other in a matrix, and the liquid crystal composition (51) is sandwiched therebetween.

Then, each signal electrode Xi (11) and scan electrode Yj (31)
Are the signal electrode drive circuit (71) and the scan electrode drive circuit (81)
And the liquid crystal display device (1) is constituted. Here, the signal electrode Xi (11) and the scanning electrode Yj (31) are formed of ITO (Indium Tin Oxide) having a resistance value of 20Ω / □, respectively, and the liquid crystal composition (51) is formed of the electrodes (11), (31). ) Are twisted and pinched by a predetermined amount by the alignment films (15) and (35) provided thereon.

Polarizing plates (25) and (45) are provided on the outer surface of each of the electrode substrates (21) and (41), and the super twist type liquid crystal display device (1) used for light transmission of the present embodiment has a structure. Have been.

The signal electrode drive circuit (71) includes a shift register unit (73) that outputs video signals in parallel, and a switching element unit (75) that controls output from the shift register unit (73).
And an integrated circuit element (77) having 160 output terminals constituted by
160) and (91) connect the output terminal of the signal electrode drive circuit (71) to the signal electrode Xi (11).

Then, the signal electrode X1 (1) on the scan electrode drive circuit (81) side
The signal electrode drive circuit (7) is connected by the connection wiring RXi (91) whose resistance gradually decreases in the direction from the signal electrode X160 (11) to the signal electrode X160 (11).
1) and the signal electrode Xi (11) are connected. And
This makes it possible to correct the effective voltage drop due to the drive voltage waveform distortion by the drive voltage applied to the signal electrode Xi (11).

The scan electrode drive circuit (81) includes a shift register (83
a), (83b) and (83c) and the switch elements (85) and (8
(5), (85) and three integrated circuit elements (87
a), (87b), and (87c) are combined, and are connected to the scan electrode drive circuit (81) by connection wirings RYj (j = 1, 2,..., 400) (95). I have.

In the liquid crystal display device (1) thus configured,
A uniform driving voltage can be applied to any pixel formed by the scanning electrode Yj (31) and the signal electrode Xi (11). As shown by the curve (a) in FIG. A uniform transmittance could be obtained on Xj (31).

On the other hand, in the conventional liquid crystal display device in which the resistance value of the connection wiring RXi (91) is uniform, it was not possible to obtain a uniform light transmittance as shown in FIG.

As described above, according to the liquid crystal display device (1) of the present embodiment,
By gradually changing the resistance value of the connection wiring Rxi (91) so that a uniform effective voltage is applied to each pixel, display characteristics can be significantly improved as compared with the related art.

In the present embodiment, the super twist type liquid crystal display device (1) used in the light transmission type has been described as an example, but the present invention is not limited to this, and for example, MIN (Metal-Insa
The same effect can be obtained even in a liquid crystal display device having a two-terminal switching element such as a tor-metal element.

The liquid crystal display device (1) described above has a configuration in which a liquid crystal composition (51) is sandwiched between a pair of electrodes (11) and (31) formed in a matrix. An active matrix liquid crystal display device comprising a liquid crystal composition sandwiched between an electrode substrate having a three-terminal switching element such as a thin film transistor connected to an electrode crossing portion and an electrode substrate having a common electrode formed thereon. May be.

In such an active matrix type liquid crystal display device, the resistance value of the connection wiring connecting the electrode driving circuit and each electrode is set as described above so as to eliminate the variation of the signal voltage waveform input to the source electrode of the thin film transistor. , A drive voltage waveform having a corrected waveform distortion is output from the drain electrode of the thin film transistor at each location, and a uniform display image can be obtained.

Further, as another method, there is a method in which the channel width of the thin film transistor connected to the electrode crossing portion is regularly changed so as to correct the variation of the waveform distortion, whereby a uniform display image can be obtained in various places. it can.

Second Embodiment Hereinafter, a liquid crystal display device (1) according to a second embodiment of the present invention will be described in detail with reference to FIG. The liquid crystal cell (3) of this liquid crystal display device (1) has an electrode width of 0.33 as in the above-described embodiment.
160 signal electrodes Xi formed in mm (i = 1,2, ..., 160)
A first electrode substrate (21) provided with (11) and an electrode width of 40
The electrodes (11) and (31) of the second electrode substrate (41) provided with zero scanning electrodes Yj (j = 1, 2,..., 400) (31) are opposed to each other in a matrix, and An object (51) is pinched.

Then, each signal electrode Xi (11) and scan electrode Yj (31)
Are the signal electrode drive circuit (71) and the scan electrode drive circuit (81)
And the liquid crystal display device (1) is constituted. Here, the signal electrode Xi (11) and the scanning electrode Yj (31) are each formed of ITO (Indium Tin Oxide) having a resistance value of 20Ω / □, and the liquid crystal composition (51) is formed of the electrodes (11), (31). ) Are twisted and pinched by a predetermined amount by the alignment films (15) and (35) provided thereon.

Polarizing plates (25) and (45) are provided on the outer surface of each of the electrode substrates (21) and (41), and the super twist type liquid crystal display device (1) used for light transmission of the present embodiment has a structure. Have been.

The signal electrode drive circuit (71) or the scan electrode drive circuit (81) is an integrated circuit device (78), (88a) having 160 output terminals composed of a shift register section (73) and a switch element section (75). (88b) and (88c) are combined, and the channel width of the transistor constituting the last-stage switch element portion (75) of the signal electrode drive circuit (71) is the same as that of the scan electrode Yj (31). It is changed so as to correct the variation of the waveform distortion caused by the wiring resistance. That is, the signal electrodes X1 to X4 of the signal electrode Xi (11)
0 is the first group (11a), signal electrode X41 to signal electrode X15
0 is the second group (11b), signal electrode X151 to signal electrode X1
60 is divided into three groups, such as a third group (11c), and the channel width of the transistor is gradually increased from the first group (71a), and the output from the signal electrode driving circuit (71) is changed stepwise. I let it.

In the liquid crystal display device (1) thus configured,
Similar to the above-described embodiment, as shown by the curve (a) in FIG. 3, uniform display characteristics are obtained regardless of the distance from the voltage supply side of the inspection electrode Yj (31) to a certain signal electrode Xi (11). I was able to.

In the liquid crystal display device (1) of the present embodiment, the liquid crystal cell (3) side can be formed exactly the same as the conventional one, so that the productivity or reliability of the liquid crystal display device (1) is the same as the conventional one. And uniform display characteristics can be obtained.

In the present embodiment, the variation of the voltage waveform distortion is corrected particularly on the signal electrode drive circuit (71) side of the liquid crystal display device (1), but the correction of the voltage waveform distortion is corrected on the scan electrode drive circuit (81) side. Needless to say, it may be done.

In addition, in the liquid crystal display device (1) of the present embodiment, the variation in the wiring resistance value due to the wiring length of the electrodes (11) and (31) from the driving circuits (71) and (81) is taken into consideration. However, by simultaneously correcting such variations in the wiring resistance, it is possible to obtain better display characteristics.

Here, the correcting means is configured by changing the channel width of the transistor constituting the last-stage switch element section (75) of the signal voltage drive circuit (71). The correction may be made by connecting resistors having different resistance values in series to (75).

In the above-described embodiment, the super twist type liquid crystal display device (1) used for light transmission is shown as an example, but the present invention is not limited to this. For example, a switching element is provided for each pixel. An active matrix type liquid crystal display device may be used. In this case, for example, as a method of eliminating the variation of the gate pulse waveform distortion input to the gate electrode, a method of regularly eliminating the variation of the gate pulse waveform distortion in advance on the signal electrode driving circuit side that applies a voltage to the signal electrode is used. It is preferable to provide a correction means connected to the output of the signal electrode drive circuit (71) so that a drive voltage having a varied waveform is applied.

Third Embodiment Hereinafter, a liquid crystal display device (1) according to a third embodiment of the present invention will be described with reference to FIG. 5, omitting the same parts as those in the above-described embodiment.

The signal electrode drive circuit (71) includes a shift register (73
a), (73b), (73c) and the switch elements (75a), (75
b) and (75c), which are constituted by three types of integrated circuit elements (77a), (77b) and (77c) having different outputs.

This first integrated circuit element (77a) has 40 output terminals,
The second integrated circuit device (77b) has 110 output terminals, and the third integrated circuit device (77c) has 10 output terminals.

Then, the first integrated circuit element (77
a) is a first group of signal electrodes (11a) (signal electrodes X1 to X1).
X40), the second integrated circuit element (77b)
Group (11b) (signal electrodes X41 to X149), the third integrated circuit element (77c) includes a second group (11b) of signal electrodes.
(Signal electrodes X150 to X160) by connection wiring (91).

The scan driving circuit (81) includes a shift register (83a),
(83b), (83c) and the switching elements (75a), (75
b) and (75c) are combined, and the output terminal is connected to each scanning electrode Yj (31) by connection wiring RYj (j = 1, 2, 400) (95). .

By configuring the liquid crystal display device (1) in this way, the variation of the voltage waveform distortion from the scan electrode drive circuit (81) is corrected, and the signal electrode Xi ( 11) A uniform light transmittance could be obtained regardless of the distance from the voltage supply side.

In the liquid crystal display device (1) of this embodiment, a signal electrode drive circuit (71) is constituted by three types of integrated circuit elements (87a), (87b), and (87c). Thereby, the integrated circuit elements (87a), (87b),
(87c) can be manufactured easily and at a high yield, and the overall cost of the liquid crystal display device (1) can be reduced.

According to the liquid crystal display device (1) of the present embodiment, the voltage waveform distortion is corrected on the signal electrode drive circuit (81) side, but the variation of the voltage waveform distortion is corrected on the scan electrode drive circuit (81) side. May be performed. In addition to the simple matrix type liquid crystal display device shown here, for example, even in the case of an active matrix type liquid crystal display device, by applying the configuration of the liquid crystal display device (1) of this embodiment, voltage waveform distortion can be reduced. The variation is corrected, and a uniform effective voltage can be applied to each pixel, so that uniform and high display quality can be secured.

[Effects of the Invention] As described in detail above, according to the liquid crystal display device of the present invention, the voltage waveform distortion of the liquid crystal liquid crystal drive voltage is reliably corrected,
A uniform effective voltage can be applied to each pixel. Thereby, it has become possible to provide a liquid crystal display device having excellent display characteristics.

In particular, by using several types of integrated circuit elements having different output characteristics as means for correcting the voltage waveform distortion of the liquid crystal driving voltage, the conventional liquid crystal cell can be used as it is, and mass production can be performed with high reliability as in the past. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic structural view of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 2 is a diagram showing the liquid crystal display device in FIG.
FIG. 3 is a schematic cross-sectional view of a liquid crystal cell taken along a line, FIG. 3 is a diagram showing a light transmittance on a vertical axis, and taking each pixel on a signal electrode Xi on a horizontal axis to show a change state of light transmittance. FIG. 4 is a schematic configuration diagram of a liquid crystal display device according to a second embodiment of the present invention, FIG. 5 is a schematic configuration diagram of a liquid crystal display device according to a third embodiment of the present invention, and FIG. FIG. 9 is a diagram showing waveform distortion due to wiring resistance, with the voltage application time taken on the horizontal axis. (1) Liquid crystal display device (3) Liquid crystal cell (11) Signal electrode (31) Scanning electrode (71) Signal electrode drive circuit (73), (83) Shift register section (75), (85): Switching element (77), (87): Integrated circuit element (81): Scan electrode drive circuit (91), (95): Connection wiring

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Kinoshita 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Yokohama Office (72) Inventor Masahito Ishikawa 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Toshiba Corporation Inside Yokohama Works (72) Inventor Yasutoshi Hirai 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Yokohama Works (72) Inventor Masato Shoko 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Prefecture Inside Toshiba Yokohama Works (56) References JP-A-63-81328 (JP, A) JP-A-62-232622 (JP, A) JP-A-60-230699 (JP, A)

Claims (1)

(57) [Claims] A plurality of first electrodes each having one end connected to a first drive circuit for supplying a drive voltage; and one end connected to a second drive circuit for supplying a drive voltage; A liquid crystal display device comprising: a plurality of second electrodes arranged in a matrix with respect to the electrodes; wherein the first drive circuit includes a serial input signal corresponding to each of the first electrodes. A conversion unit configured to convert the signal into a parallel signal and output the converted signal to each of the first electrodes; and a correction unit configured to perform a correction on the signal converted into the parallel signal. Correction is performed so that a drive voltage having an effective value smaller than that of the first electrode that intersects the other end of the second electrode is supplied to the first electrode that intersects one end of the second electrode. A predetermined second of the electrodes
An effective voltage applied to an intersection between the electrode and the first electrode that intersects the one end of the second electrode;
A liquid crystal display device, wherein an effective voltage applied to an intersection between the electrode and the first electrode that intersects the other end of the second electrode is substantially equal.