JP2001305564A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element having a high aperture ratio and high response speed without heightening the total driving voltage. SOLUTION: In the liquid crystal display element having a display system in which display is performed by applying an electric field to a liquid crystal interposed between substrates in a direction nearly parallel to a surface of the substrate by using electrodes 101 and 102 provided on the substrate, the electric field is specified to be applied to the liquid crystal in a partial region of each pixel more intensely than to the liquid crystal in the other region. Since the response speed of a portion of the liquid crystal in the pixel is made high, the response of the other portion of the liquid crystal also follows it and the response of the liquid crystal in the total pixel is also made high. And since the electrodes are disposed so that the electric field is applied more intensely to only a part of the pixel, the aperture ratio is not reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device used for a liquid crystal display device. In particular, the present invention relates to a liquid crystal display device of a system in which the direction of an electric field applied to liquid crystal is substantially parallel to the surface of a substrate.

[0002]

2. Description of the Related Art As a display method of a liquid crystal display element, a liquid crystal operates by applying an electric field in a direction substantially perpendicular to the substrate surface by using opposed transparent electrodes formed respectively on two substrates. The twisted nematic display method is typical. Another display method is a method in which the direction of an electric field applied to the liquid crystal is substantially parallel to the substrate surface.
As an example of this method, a method using a comb-shaped electrode pair has been proposed. In this case, the electrodes need not be transparent,
An opaque metal electrode having high conductivity is used. This display method in which the direction of the electric field applied to the liquid crystal is made substantially parallel to the substrate surface has an extremely wide viewing angle.

[0003]

FIG. 11 is a plan view showing electrodes in a conventional liquid crystal display element in which an electric field substantially parallel to a substrate surface is applied. 701 is a comb-shaped drive electrode, 7
02 is a comb-shaped common electrode, 703 is a gate wiring, 704 is a source wiring, and 705 is a transistor. Drive electrode 7
When a voltage is applied between the liquid crystal molecules 01 and the common electrode 702, the alignment direction of the liquid crystal molecules is changed accordingly. The structure of the liquid crystal display device which applies a substantially parallel electric field to the substrate surface in this example has an advantage that the viewing angle is extremely wide, but has a problem that the aperture ratio is small and the response speed is slow. .

In order to solve this problem, for example, by increasing the number of electrodes and narrowing the interval between the electrodes,
The electric field acting on the liquid crystal molecules is strengthened, and the orientation direction of the liquid crystal molecules is changed quickly. In this manner, a liquid crystal display device having a high response speed can be realized. However, in this liquid crystal display element, since the number of electrodes is large, there is a problem that the ratio of the electrode area occupying the pixel region is large and the aperture ratio is reduced.

[0005] Further, by increasing the voltage applied to the liquid crystal,
It is also possible to increase the electric field acting on the liquid crystal molecules. However, when the driving voltage is extremely increased, a driving peripheral circuit must be adapted to the driving voltage.

An object of the present invention is to provide a liquid crystal display device having a high aperture ratio and a high response speed without increasing the driving voltage as a whole.

[0007]

In order to solve the above-mentioned problems, a liquid crystal display device according to the present invention generates a strong electric field in a part of a pixel. As a result, the response of the liquid crystal in a part of the pixel is accelerated, and the liquid crystal in the other part responds accordingly, and the response of the entire pixel is also accelerated. In addition, since the electrodes are arranged so as to generate a strong electric field only in a part of the pixel, the aperture ratio does not decrease.
Therefore, a liquid crystal display element having a high aperture ratio and a high response speed can be realized.

More specifically, the basic structure of the liquid crystal display device of the present invention is to display an image by applying an electric field to a liquid crystal sandwiched between the substrates in a direction substantially parallel to the surface of the substrate by electrodes provided on the substrate. In the liquid crystal display device of the method of performing the above, a stronger electric field is applied to the liquid crystal in a part of the area in each pixel than the liquid crystal in the other area.

In this configuration, the electrodes may be formed as comb electrodes only in a part of each pixel.

Further, in the above basic configuration, each pixel may include a comb-shaped electrode, and the length of the comb-shaped electrode may be varied within one pixel. Alternatively, a comb-shaped electrode may be included in each pixel, and the interval between the electrodes of the comb-shaped electrode may be different in one pixel.

Further, in the above basic configuration, each pixel includes at least a pair of first electrodes for applying an electric field to one pixel as a whole, and a pair of electrodes having an interval smaller than the interval between the first electrode pairs. And at least a pair of second electrodes for applying an electric field to a part of the pixel. In this configuration, one of the second pair of electrodes may be configured to also serve as one of the first pair of electrodes.

[0012] In the above structure, a structure may be employed in which a first transistor for applying a voltage to the first pair of electrodes and a second transistor for applying a voltage to the second pair of electrodes are provided. In this configuration, the output voltage of the second transistor can be configured not to be held by the storage capacitor.

[0013] In the above basic configuration, there is provided a first drive electrode driven by a first transistor and a second drive electrode driven by a second transistor, and a drive applied to the first drive electrode. The configuration can be such that the voltage and the drive voltage applied to the second drive electrode are different. In this configuration, the average value of the drive voltage applied to the first drive electrode and the average value of the drive voltage applied to the second drive electrode may be substantially equal to the voltage applied to the common electrode. it can.

In the above basic configuration, a configuration may be adopted in which a conductor insulated from other electrodes and wiring is disposed between the drive electrode and the common electrode.

Further, in the above basic configuration, a configuration may be adopted in which a conductor insulated from other electrodes and wirings is arranged between the drive electrodes.

A liquid crystal display device can be formed by using the liquid crystal display device having any one of the above structures.

[0017]

(Embodiment 1) FIG. 1 shows Embodiment 1 of the present invention.
3 is a plan view showing an electrode of the liquid crystal display element in FIG. 10
1 is a comb-shaped drive electrode, 102 is a comb-shaped common electrode, 103
Is a gate wiring, 104 is a source wiring, and 105 is a transistor.

When a voltage is applied between the driving electrode 101 and the common electrode 102, the region A 11 in which the electrode has a comb shape is formed.
At 0, a strong electric field is applied to the liquid crystal molecules, and the orientation direction of the liquid crystal molecules is changed quickly. Following this, the orientation of the liquid crystal molecules in the vicinity of the region A 110 is changed, and finally the orientation of the liquid crystal molecules in the entire unit pixel is changed.

No strong electric field is generated in the B region 111 having no comb-shaped electrode. However, since the liquid crystal molecules in the B region 111 where the electric field is weak are changed in accordance with the change in the orientation of the liquid crystal molecules in the A region 110 where the electric field is strong, the liquid crystal display element without the comb-shaped electrode is used. The orientation of the liquid crystal molecules is converted more quickly than in the above.

Therefore, the response speed of the liquid crystal display element is almost equal to the case where the comb-shaped electrode works on the whole pixel, and
A decrease in the aperture ratio can be suppressed.

(Embodiment 2) FIG. 2 is a plan view showing an electrode of a liquid crystal display element according to Embodiment 2. FIG. 201 is a drive electrode, 202 is a common electrode, 203 is a gate wiring, 20
4 is a source wiring, and 205 is a transistor. The drive electrode 201 and the common electrode 202 form a comb-shaped electrode portion having a narrow electrode interval in a part A region 210 of a unit pixel, where a region with a strong electric field is formed. In the A region 210 where the electric field is strong, a strong electric field is applied to the liquid crystal molecules, and the orientation of the liquid crystal molecules is quickly converted. Following the liquid crystal whose orientation has been converted, the orientation of the surrounding liquid crystal molecules is also quickly changed. Thus, a liquid crystal display device having a high aperture ratio and a high response speed can be realized.

Similarly, the electrodes shown in FIGS. 3 (a) and 3 (b) also have an A region 210a or 210b with a narrow electric field and a strong electric field in a part of the unit pixel. The effect can be achieved.

(Embodiment 3) FIG. 4 is a plan view showing an electrode of a liquid crystal display element in Embodiment 3. FIG. 5 is a waveform diagram showing signal waveforms supplied to the electrodes of FIG.

Reference numeral 301 denotes a first driving electrode, 302 denotes a common electrode, 304 denotes a first source wiring, 306 denotes a second driving electrode, 308 denotes a second source wiring, and 303 denotes a gate wiring. 305 is a first transistor, and 307 is a second transistor. Reference numeral 309 denotes a storage capacitor unit 309 provided on the first drive electrode 301. Second drive electrode 306
Does not have a storage capacitor section.

The pulse signal 401 shown in FIG. 5A is supplied to the gate wiring 303. First and second source lines 3
Signals 402 and 403 shown in FIGS. 5B and 5C are supplied to 04 and 308, respectively.

When the pulse signal 401 is supplied, the first
Transistor 305 operates, and the first drive electrode 301
Is applied with the voltage of the first source wiring 304. Further, the second transistor 307 operates, and the voltage of the second source wiring 308 is applied to the second drive electrode 306. When the pulse signal 401 falls, the voltage is held because the storage capacitor portion 309 is provided in the first drive electrode 301. However, since the second drive electrode 306 is not provided with a storage capacitor portion, no voltage is held. Therefore, as shown in FIGS. 5D and 5E,
A drive voltage 404 is applied to the first drive electrode 301, and a drive voltage 405 is applied to the second drive electrode 306.

Since the distance between the second drive electrode 306 and the common electrode 302 is smaller than the distance between the first drive electrode 301 and the common electrode 302, a strong electric field is applied to the liquid crystal molecules in the region 310, and the orientation of the liquid crystal molecules is changed. Convert quickly. Pulse signal 4
01 falls, the first drive electrode 301 and the common electrode 3
When the electric field is generated during the period 02, the orientation of the liquid crystal molecules in the region 310 has already been changed, and the other regions, that is, the first driving electrode 301 and the second driving electrode 3
In addition, the orientation of the liquid crystal molecules during the period of 06 is also quickly changed. Therefore, the aperture ratio is almost the same as when there is no comb-shaped electrode, and a liquid crystal display device with a high response speed can be realized. First drive electrode 3
01 and the voltage applied to the second drive electrode 306 are:
It can be controlled by each source wiring. Therefore, the electric field applied to the liquid crystal molecules can be controlled, and the response can be further accelerated.

Further, in this embodiment, since the direction of the electric field of the whole pixel is constant, there is an advantage that the alignment of the liquid crystal molecules is not disturbed.

(Embodiment 4) FIG. 6A shows Embodiment 4.
3 is a plan view showing an electrode of the liquid crystal display element in FIG. FIG.
The signal waveform shown in the waveform diagram of FIG. 5 is supplied to the electrode (a). Reference numeral 501 denotes a first driving electrode, 502 denotes a common electrode, 504 denotes a first source wiring, 506 denotes a second driving electrode, 508 denotes a second source wiring, and 503 denotes a gate wiring. 505 is a first transistor, and 507 is a second transistor.

The pulse signal 401 is supplied to the gate wiring 503. Signals 402 and 403 are supplied to the first and second source wirings 504 and 508, respectively. For example, the potential of the common electrode 502 is 2.5 V, and the voltage of the first and second source wirings 504 and 508 is -2.5 V, respectively.
V, 7.5V. However, these values are examples, and the present invention is not limited to these values. In short, the drive voltage applied to the first drive electrode 501 and the second drive electrode 506
Is made substantially equal to the voltage applied to the common electrode 502.

When the pulse signal 401 is supplied, the first
Transistor 505 operates, and the first drive electrode 501
Is applied with the voltage of the first source wiring 504. Further, the second transistor 507 operates and the voltage of the second source wiring 508 is applied to the second drive electrode 506.

At this time, the voltage between the first drive electrode 501 and the second drive electrode 506 becomes 10V. For this reason,
If the distance between the electrodes is constant, the electric field applied to the liquid crystal molecules is stronger than in other regions, so that the orientation of the liquid crystal molecules is converted faster. Conversely, it is also possible to increase the aperture ratio by increasing the distance between the first and second drive electrodes with the same electric field. Therefore, the response can be made faster without lowering the aperture ratio.

Also in this embodiment, there is an advantage that the orientation of the liquid crystal molecules is not disturbed since the electric field direction of the whole pixel is constant.

As described above, in the present embodiment, the first
The average value of the drive voltage applied to the drive electrode 501 and the average value of the drive voltage applied to the second drive electrode
Since the potential is almost equal to the voltage applied to the common electrode 502, the potential of the first drive electrode 501 and the potential of the second drive electrode 506 are almost inverted with respect to the potential of the common electrode 502.
The liquid crystal panel requires AC driving from the viewpoint of life, and the source signal is inverted for each frame or line. Therefore, the first drive electrode 501 and the second drive electrode 50
It is easy in circuit to substantially invert the potential of No. 6 with respect to the potential 502 of the common electrode.

The electrode shown in FIG. 6B is a modification of the electrode shown in FIG. 6A, and the basic operation and effect are shown in FIG.
This is the same as that of the electrode.

(Embodiment 5) FIG. 7 and FIG.
FIG. 15 is a plan view illustrating an electrode of a liquid crystal display element according to a fifth embodiment. 601 is a drive electrode, 602 is a common electrode, 604 is a source wiring, and 603 is a gate wiring. 605 is a transistor.

In FIG. 7, a partial area 61 of a unit pixel is shown.
At 0, a conductor 611 is arranged between the drive electrode 601 and the common electrode 602. The presence of the conductor 611 increases the electric field in a portion of the region 610 where the conductor 611 is not provided, and the orientation of the liquid crystal molecules in the region 610 is quickly changed. Thereafter, the orientation of the liquid crystal molecules in the entire unit pixel is quickly changed by the liquid crystal in the region 610. In this manner, a liquid crystal display device having a high aperture ratio and a quick response can be realized.

The advantage of Embodiment 5 is that the degree of freedom in design is high. The size of one pixel is necessarily determined from the screen size and the resolution. Further, the voltage that can be applied to the electrode is also limited by the liquid crystal, the driving circuit, and the like. Further, as described above, simply increasing the number of electrodes lowers the aperture ratio.
However, when an electric conductor is arranged, unlike an electrode, it does not require wiring or the like, which is advantageous in terms of design and aperture ratio.

In the electrode of the liquid crystal display element shown in FIG. 8, a conductor 611 is arranged between the drive electrode 601 and the common electrode 602 in the entire area of the unit pixel. The operation is the same as in FIG.

(Embodiment 6) FIGS. 9 and 10 are plan views each showing an electrode of a liquid crystal display element in Embodiment 6. FIG. The same elements as those in the liquid crystal display element shown in FIG. 7 are denoted by the same reference numerals, and the description thereof will not be repeated.

Also in this embodiment, a conductor 611 is arranged between the electrodes. The position of the conductor is not particularly limited only between the electrodes. In FIG. 9, a conductor 611 is arranged between the drive electrode 601 and the common electrode 602, and in FIG. 10, a conductor 611 is arranged between the drive electrode 601 and the drive electrode 601. It was confirmed by experiments that the orientation of the liquid crystal molecules was changed regardless of the arrangement.

The advantage of the sixth embodiment is that the degree of freedom of design is high as in the fifth embodiment. The size of one pixel is necessarily determined from the screen size and the resolution. Further, the voltage that can be applied to the electrode is also limited by the liquid crystal, the driving circuit, and the like.
Further, as described above, simply increasing the number of electrodes lowers the aperture ratio. However, when the conductor is arranged, unlike the electrodes, it does not need to be routed, which is advantageous in terms of design and aperture ratio.

[0043]

According to the present invention, by providing a portion for generating a strong electric field in a part of a pixel, a liquid crystal display element and a liquid crystal display device having a high response speed can be realized without lowering the aperture ratio. I can do it.

[Brief description of the drawings]

FIG. 1 is a plan view showing electrodes of a liquid crystal display element according to a first embodiment of the present invention.

FIG. 2 is a plan view showing electrodes of a liquid crystal display element according to a second embodiment of the present invention.

FIG. 3 is a plan view showing another example of the electrodes of the liquid crystal display element according to the second embodiment of the present invention.

FIG. 4 is a plan view showing electrodes of a liquid crystal display element according to a third embodiment of the present invention.

FIG. 5 is a waveform chart showing a driving voltage supplied to an electrode of a liquid crystal display element according to Embodiments 3 and 4 of the present invention.

FIG. 6 is a plan view showing electrodes of a liquid crystal display element according to a fourth embodiment of the present invention.

FIG. 7 is a plan view showing electrodes of a liquid crystal display element according to a fifth embodiment of the present invention.

FIG. 8 is a plan view showing electrodes of a liquid crystal display element according to a fifth embodiment of the present invention.

FIG. 9 is a plan view showing electrodes of a liquid crystal display element according to a sixth embodiment of the present invention.

FIG. 10 is a plan view showing electrodes of a liquid crystal display element according to a sixth embodiment of the present invention.

FIG. 11 is a plan view showing electrodes of a liquid crystal display element in a conventional example.

[Explanation of symbols]

101, 201, 601, 701 Driving electrodes 102, 202, 302, 502, 602, 702 Common electrodes 103, 203, 303, 503, 603, 703 Gate wirings 104, 204, 604, 704 Source wirings 105, 205, 605, 705 Transistors 110, 210, 210a, 210b A region 111 B region 301, 501 First drive electrode 304, 504 First source wiring 305, 505 First transistor 306, 506 Second drive electrode 307, 507 Second Transistors 308, 508 second source wiring 309 storage capacitor 401 gate signal 402 first source signal 403 second source signal 404, 405 drive voltage 610 some regions 611 conductor

Claims (13)

[Claims] In a liquid crystal display element of a system in which an electric field is applied to a liquid crystal sandwiched between substrates by an electrode provided on the substrate in a direction substantially parallel to the surface of the substrate to perform display, A liquid crystal display element, wherein a stronger electric field is applied to the liquid crystal in a partial area of the liquid crystal than in the liquid crystal in another area. 2. The liquid crystal display device according to claim 1, wherein the electrodes are formed as comb electrodes only in a part of each pixel. 3. The liquid crystal display device according to claim 1, wherein each pixel includes a comb-shaped electrode, and the electrodes of the comb-shaped electrode have different lengths within one pixel. 4. The liquid crystal display device according to claim 1, wherein each pixel includes a comb-shaped electrode, and an interval between the electrodes of the comb-shaped electrode is different in one pixel. 5. In each pixel, at least one pair of first electrodes for applying an electric field to one entire pixel, and one pair of electrodes having an interval smaller than the interval between the first electrode pairs, and a part of the pixel. 2. The liquid crystal display device according to claim 1, further comprising at least a pair of second electrodes for applying an electric field to the liquid crystal display device. 6. The liquid crystal display device according to claim 5, wherein one of the second pair of electrodes also serves as one of the first pair of electrodes. 7. A first method for applying a voltage to a first pair of electrodes.
6. The liquid crystal display device according to claim 5, further comprising: a second transistor for applying a voltage to the second pair of electrodes. 8. The liquid crystal display device according to claim 7, wherein the output voltage of the second transistor is configured not to be held by the storage capacitor. 9. A semiconductor device comprising: a first drive electrode driven by a first transistor; and a second drive electrode driven by a second transistor, wherein a drive voltage applied to the first drive electrode and 2. The liquid crystal display device according to claim 1, wherein a driving voltage applied to the second driving electrode is different. 10. An average value of a driving voltage applied to a first driving electrode and a driving voltage applied to a second driving electrode is substantially equal to a voltage applied to a common electrode. A liquid crystal display device according to claim 9. 11. The liquid crystal display device according to claim 1, wherein a conductor insulated from other electrodes and wiring is disposed between the drive electrode and the common electrode. 12. A conductive member insulated from other electrodes and wiring between drive electrodes.
3. The liquid crystal display device according to item 1. 13. The method according to claim 1, wherein:
13. A liquid crystal display device using the liquid crystal display element according to item 9.