JP2000292802A - Horizontal electric field type active matrix liquid crystal display - Google Patents

Abstract

(57) [Problem] To provide an in-plane switching type active matrix liquid crystal display device which obtains a good display image without lowering the contrast of a display image by AC driving a common line 5. SOLUTION: The first and second transparent substrates 1 and 2, a liquid crystal layer 8 sandwiched between them, and a liquid crystal drive section formed on the first transparent substrate 1 are formed by the liquid crystal drive section. A liquid crystal display device that drives a liquid crystal layer 8 by an electric field, wherein a liquid crystal driving unit includes a TFT arranged at each intersection of each scanning line 3 and each signal line 4 arranged in a matrix and each scanning line 3 and each signal line 4.
7, a pixel electrode 6 having a plurality of comb-shaped pixel electrodes 6D arranged in a pixel region surrounded by each scanning line 3 and each signal line 4,
A plurality of comb-shaped common electrodes 5 which are insulated from each pixel electrode 6
D, and every other common line 5 is connected to a different drive source, and each of the comb-shaped pixel electrodes 6D and the end of each of the comb-shaped common electrodes 5D facing the scanning line 3 are connected to a different driving source. The interval is formed narrower than the intervals of other parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lateral electric field type active matrix type liquid crystal display device, and more particularly to a lateral electric field type active matrix type liquid crystal display device having a high contrast, a wide viewing angle, and capable of displaying a good image. The present invention relates to a matrix type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, an active matrix liquid crystal display device uses a cathode ray tube (CR) by using an active element represented by a thin film transistor (TFT) for each pixel.
High-quality images comparable to T) have been obtained. And an active matrix liquid crystal display device
Because they consume less power than CRTs and can be made smaller than CRTs, they are widely used as monitors for personal computers (PCs) and workstations.

As one of the liquid crystal display devices suitable for such a monitor application, a horizontal electric field type active matrix liquid crystal display device is known. In this horizontal electric field type active matrix liquid crystal display device, a plurality of scanning lines, a plurality of signal lines, and a plurality of common lines are respectively formed and arranged on one of a pair of transparent substrates, and are opposed to pixel electrodes. Two electrodes are formed in a comb shape, and an electric field applied to the liquid crystal layer is formed in a direction substantially parallel to the surface of the transparent substrate, thereby driving the liquid crystal layer. This horizontal electric field type active matrix liquid crystal display device provides a wider viewing angle than a normal vertical electric field type active matrix liquid crystal display device in which the electric field applied to the liquid crystal layer is formed almost perpendicularly to the surface of the transparent substrate. It is the most suitable for the type monitor.

In such an in-plane switching type active matrix liquid crystal display device, as in other devices, cost reduction is demanded.
No. 152 has a means disclosed. This Japanese Patent Application Laid-Open No. Hei 7-2611
The means disclosed in No. 52 drives a common line (common line) with an AC voltage, reduces a signal driving voltage without changing an effective applied voltage to a liquid crystal layer, and generates a thin film transistor (TF).
T) Expensive driving integrated circuit (IC) constituting the driving circuit
Is low cost, and the whole is low cost.

[0005]

SUMMARY OF THE INVENTION Incidentally, Japanese Patent Application Laid-Open No.
In a known liquid crystal display device including a horizontal electric field type active matrix liquid crystal display device disclosed in Japanese Patent No. 261152, when an AC voltage is used for a common line (common line), the timing of inverting the AC voltage is as follows. Driving method of inverting in one line (1H) cycle and one screen (1V)
There is a driving method of inverting in a cycle. Among these driving methods, a driving method of inverting in a cycle of one screen (1 V) requires a low frequency of an AC voltage, and thus requires less power consumption.

However, in the driving method of inverting in one screen (1 V) cycle, the positive and negative polarities of the effective applied voltage are alternately alternated every other row. It is necessary to connect every other power supply to another power supply system, and it is necessary to arrange common lines respectively connected to at least two or more power supplies.

In this case, in a liquid crystal display device in which there are common lines respectively connected to two power sources and the polarity of the power source input to every other common line is different, the liquid crystal display devices are adjacent in the signal line direction. The polarity of the voltage applied to the liquid crystal layer of the pixel is different. Particularly, since the polarity of the common voltage is always opposite to the center voltage of the common voltage, the common voltage is common between the common lines of adjacent pixels in the signal line direction. This means that a voltage equal to the voltage amplitude is always applied.

In general, not only the in-plane switching type active matrix liquid crystal display device but also many liquid crystal display devices can be manufactured at the same time as much as possible because the fewer the number of manufacturing steps, the lower the manufacturing cost. In many cases, the steps of forming various components are performed as one step, for example, the formation of a common line and a scanning line is performed as one step on the same layer. At this time, if different lines or electrodes are placed on the same layer due to restrictions on the manufacturing process,
The wires or electrodes need to be arranged at regular intervals. Such an arrangement state is caused between a comb-shaped common electrode derived from a common line in a horizontal electric field type active matrix liquid crystal display device and a comb-shaped pixel electrode derived from a pixel electrode in a comb shape. Has also been implemented.

Here, FIGS. 10 (a), 10 (b), 10 (c)
FIG. 3 is a partial configuration diagram showing an example of an arrangement relationship between a comb-shaped common electrode, a comb-shaped pixel electrode, and a scanning line in a known lateral electric field type active matrix liquid crystal display device. (A) shows the state of the electric field formed between the comb-shaped common electrode and the comb-shaped pixel electrode, and (b) shows the state of the electric field formed between the scanning line and the comb-shaped common electrode. (C) is formed between the comb-shaped common electrode and the comb-shaped pixel electrode affected by the electric field between the scanning line and the comb-shaped common electrode. It shows the state of the electric field.

In FIGS. 10A to 10C, reference numeral 51 denotes a scanning line, 52 denotes a comb-shaped common electrode, 53 denotes a comb-shaped pixel electrode, and 54 denotes a light shielding layer.

As shown in FIG. 10A, an electric field indicated by an arrow is generated between the comb-shaped common electrode 52 and the comb-shaped pixel electrode 53, and the electric field drives the liquid crystal layer. . In this case, if it is not affected by the external electric field, the region between the comb-shaped common electrode 52 and the comb-shaped pixel electrode 53 has the comb-shaped common electrode 52 and the comb-shaped pixel An electric field is generated in a direction orthogonal to the electrode 53, and the electric field at the tip of the comb-shaped common electrode 52 and the tip of the comb-shaped pixel electrode 53 slightly expands outward. Since the display image is covered with the light shielding layer 54, the display image is not affected at all.

However, as shown in FIG. 10B, when the phases of the driving voltages supplied to the common line (not shown) of the adjacent pixels are different, the comb-shaped common electrode 52 and the comb-shaped pixel An electric field orthogonal to the electric field generated between the electrode 53 and the electrode 53 is generated in a region between the scanning line 51 and the comb-shaped common electrode 52.

For this reason, as shown in FIG. 10C, the electric field generated between the comb-shaped common electrode 52 and the comb-shaped pixel electrode 53 is generated by the scanning line 51 and the comb-shaped common electrode 52. Greatly affected by the electric field generated between them, not only the electric field at the tips of the comb-shaped common electrode 52 and the comb-shaped pixel electrode 53, but also
The electric field generated in a region away from the tip is also disturbed. Then, the comb-shaped common electrode 52 and the comb-shaped pixel electrode 5
3 is not covered with the light-shielding layer 54, and the display image is affected by the disturbance of the electric field in this region. In particular, when a black image is displayed on a display image, if the electric field applied to the liquid crystal layer is disturbed, the light transmittance of that portion in the liquid crystal layer is increased, and black luminance (minimum luminance during black display) is increased. However, the contrast of the display image is reduced, and a good display image cannot be obtained.

On the other hand, it is conceivable that the arrangement area of the light-shielding layer 54 is increased to cover the region where the electric field is disturbed. However, if the arrangement area of the light-shielding layer 54 is increased, the aperture ratio of the displayed image decreases. This is not preferable as a countermeasure against a decrease in contrast.

The present invention has been made in view of such a technical background, and an object of the present invention is to reduce the contrast of a display image when a common line between pixels adjacent in the signal line direction is AC-driven. Another object of the present invention is to provide a lateral electric field type active matrix liquid crystal display device capable of obtaining a good display image.

[0016]

In order to achieve the above object, an in-plane switching mode active matrix liquid crystal display device according to the present invention is sandwiched between first and second transparent substrates and between the first and second transparent substrates. And a liquid crystal driving unit formed on the first transparent substrate. The liquid crystal layer is driven by a parallel electric field formed by the liquid crystal driving unit. A plurality of scanning lines and a plurality of signal lines arranged in a shape, a plurality of active elements arranged at each intersection of the plurality of scanning lines and the plurality of signal lines, a plurality of scanning lines and A plurality of pixel electrodes arranged in a portion surrounded by a plurality of signal lines, connected to a plurality of active elements, and formed with a plurality of comb-shaped pixel electrodes, respectively, and arranged in parallel with a plurality of scanning lines. ,
A plurality of common lines that are insulated with respect to the plurality of pixel electrodes and each form a plurality of comb-shaped common electrodes, and adjacent common lines each operate in a different phase. Each of the comb-shaped pixel electrodes and the plurality of comb-shaped common electrodes has first means formed so that the interval between the tip portions facing the scanning lines is smaller than the interval between the other portions.

Further, in order to achieve the above object, an in-plane switching mode active matrix liquid crystal display device according to the present invention comprises:
The liquid crystal device includes first and second transparent substrates, a liquid crystal layer sandwiched between the first and second transparent substrates, and a liquid crystal driving unit formed on the first transparent substrate. The liquid crystal driving section drives the liquid crystal layer, and the liquid crystal driving section includes a plurality of scanning lines and a plurality of signal lines arranged in a matrix in an insulated state, and a plurality of scanning lines and a plurality of signal lines. A plurality of active elements arranged at each intersection, and a plurality of comb teeth arranged at a portion surrounded by a plurality of scanning lines and the plurality of signal lines, connected to the plurality of active elements and each having a plurality of comb teeth Pixel electrodes forming a plurality of pixel electrodes, and a plurality of common lines arranged in parallel with a plurality of scanning lines, insulated from the plurality of pixel electrodes, and formed with a plurality of comb-shaped common electrodes, respectively. And
Adjacent common lines operate in different phases, and each scanning line, each common line, and each comb-shaped common electrode are stacked and arranged via an insulating layer, and a plurality of comb-shaped pixel electrodes and a plurality of comb-shaped pixel electrodes are arranged. The tip of the comb-shaped common electrode is provided so as to overlap or be close to the scanning line, and is provided with second means arranged so as to overlap with the light shielding layer.

According to the first means, the comb-shaped pixel electrode connected to the pixel electrode and the comb-shaped common electrode connected to the common line have a width of at least one end portion larger than that of the other portions. The width of the comb-shaped pixel electrode and the tip of the comb-shaped common electrode are made narrower than the space between the other portions. The disturbing rate of the electric field formed in the region at the narrow interval between the tip ends of the electrodes can be extremely reduced, and as a result, a good display image can be obtained without lowering the contrast of the display image.

According to the second means, since the scanning lines and the common lines and the comb-like common electrodes are stacked and arranged via the insulating layer, the comb-like pixel electrodes connected to the pixel electrodes are arranged. Each end of the comb-shaped common electrode connected to the common line can be extended below the light-shielding layer, and formed between each end of the comb-shaped pixel electrode and each end of the comb-shaped common electrode. The display image in the area affected by the disturbed electric field can be covered with the light shielding layer. As a result, a good display image can be obtained without lowering the contrast of the display image.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram showing a first embodiment of a lateral electric field type active matrix liquid crystal display device according to the present invention, and the left side is a plan view showing a liquid crystal drive section constituting four adjacent pixels. The right side is a plan view showing a state in which a light shielding layer is overlaid on the same pixel.

FIG. 2 is a cross-sectional view taken along the line AA 'of the lateral electric field type active matrix liquid crystal display device shown in FIG. 1, and FIG. 3 is a lateral electric field type active matrix liquid crystal display device shown in FIG. FIG. 4 is a cross-sectional configuration diagram of the BB ′ line portion of the device, and FIG. 4 is a cross-sectional configuration diagram of the CC ′ line portion of the horizontal electric field type active matrix liquid crystal display device shown in FIG.

1 to 4, 1 is a first transparent substrate, 2 is a second transparent substrate, 3 is a scanning line, 4 is a signal line, 5 is a common line, 5D is a comb-like common electrode, 6 is a pixel electrode, 6D is a comb-shaped pixel electrode, and 7 is a thin film transistor (T
FT), 7G is a gate electrode, 7D is a drain electrode, 7S
Is a source electrode, 7H is a semiconductor layer, 7C is an ohmic contact layer, 8 is a liquid crystal layer, 9 is an insulating layer, 10 is a protective layer, 1
1 is a first polarizing plate, 12 is a first alignment film, 13 is a light shielding layer (black matrix), 14 is a color filter, 15 is a flattening resin film, 16 is a second polarizing plate, 17 is a second alignment film,
8 is an auxiliary capacity.

Then, as shown in FIGS. 1 and 2,
On one surface of the first transparent substrate 1, a scanning line 3, a common line 5, and a comb-like common electrode 5D derived from the common line 5 are formed, and an insulating layer 9 is formed so as to cover those surfaces. Is done.
The signal line 4, the pixel electrode 6, and the comb-shaped pixel electrode 6D derived from the pixel electrode 6 are formed on the insulating layer 9, and a protective layer 10 is formed so as to cover the surfaces thereof. A first alignment film 12 is formed on 10. A first polarizing plate 11 is bonded to the other surface of the first transparent substrate 1. On one surface of the second transparent substrate 2, a matrix-shaped light-shielding film 13 and a color filter 14 are formed so as to cover the openings of the light-shielding film 13, and a flattening resin film 15 is formed so as to cover those surfaces. Is formed, and a second alignment film 17 is formed on the flattening resin film 15. On the other surface of the second transparent substrate 2,
The second polarizing plate 16 is joined. A first alignment film 12 and a second alignment film 17 are provided between the first transparent substrate 1 and the second transparent substrate 2.
The liquid crystal layer 8 is disposed so as to be in contact with the liquid crystal layer, thereby forming a liquid crystal display element as a whole.

In this case, the plurality of scanning lines 3 are arranged in parallel, and the common lines 5 are arranged between the adjacent scanning lines 3 in parallel with the scanning lines 3. The plurality of signal lines 4 are arranged in parallel with each other and orthogonal to each scanning line 3, and a thin film transistor 7 is provided at an intersection of each scanning line 3 and each signal line 4.
Are formed. As shown in FIG. 3, the thin film transistor 7 includes a semiconductor layer 7H mainly made of a-Si, and a drain electrode 7D and a source electrode 7S respectively coupled to the semiconductor layer 7H via an ohmic contact layer 7C.
And a gate electrode 7G coupled to the semiconductor layer 7H via the insulating layer 9. The drain electrode 7D is connected to the corresponding signal line 4, the source electrode 7S is connected to the corresponding comb-shaped pixel electrode 6D, and the gate electrode 7G is connected to the corresponding scanning line 3. The auxiliary capacitance 18 has a capacitance value Cstg, and is formed at a portion where the common line 5 and the pixel electrode 6 overlap with the insulating layer 9 interposed therebetween, as shown in FIG.

The comb-shaped common electrode 5D is derived from the common line 5 in a comb-like shape so as to be parallel to the signal line 4, and extends to a position where the tip end is in close proximity to the scanning line 3. ,
And it is comprised so that a front-end | tip part may become wider than another part. The comb-shaped pixel electrode 6 </ b> D is adjacent to the comb-shaped common electrode 5 </ b> D in a comb shape from the pixel electrode 6, in parallel with the signal line 4.
Similarly, the leading end extends to a position close to and opposed to the scanning line 3, and the leading end is wider than other portions.
Therefore, the interval between the tip of the comb-shaped common electrode 5D and the tip of the comb-shaped pixel electrode 6D is configured to be narrower than the interval between the other portions.

Further, every other common line 5 is connected to a first power supply and a second power supply, and an AC drive voltage Vc1 supplied from the first power supply and an AC drive voltage supplied from the second power supply are provided. Vc2 has opposite phases to each other. At this time, a voltage difference between the comb-shaped pixel electrode 6D and the voltage applied to the comb-shaped common electrode 5D is shown in FIG. 2 between the comb-shaped pixel electrode 6D and the adjacent comb-shaped common electrode 5D. Thus, an electric field parallel to the surfaces of the first and second transparent substrates 1 and 2 is formed in the liquid crystal layer 8.

In the lateral electric field type active matrix liquid crystal display device having the above structure, when a driving voltage is applied to each of the pixel electrode 6 and the common line 5 and the potential difference between the driving voltages is small, the liquid crystal layer 8 is transmitted. When the potential difference between the drive voltages is large, the amount of transmitted light passing through the liquid crystal layer 8 increases, and the display state becomes white. In this case, the amount of transmitted light passing through the liquid crystal layer 8 is determined by the strength of the parallel electric field formed by the potential difference of the drive voltage between the pixel electrode 6 and the common line 5. Accordingly, the alignment state of the liquid crystal molecules in the liquid crystal layer 8 changes, thereby controlling the amount of transmitted light.

FIG. 5 is a circuit diagram showing an example of an equivalent circuit in the horizontal electric field type active matrix liquid crystal display device shown in FIG.

In FIG. 5, reference numeral 19 denotes a scan electrode driving circuit,
20 is a signal electrode drive circuit, 21 is a common electrode drive circuit, 2
Reference numeral 2 denotes a liquid crystal capacitor, and other components that are the same as those shown in FIGS. 1 to 4 are denoted by the same reference numerals.

The scanning electrode driving circuit 19 is connected to each scanning line 3, the signal electrode driving circuit 20 is connected to each signal line 4, and the common electrode driving circuit 21 has two output lines 21 ₁ ,
₂ 1 ₂ are connected to every other common line 5. In the thin film transistor 7, the drain electrode is connected to the signal line 4, the source electrode 7S is connected to the common line 5 via the auxiliary capacitance 18 and the liquid crystal capacitance 22, and the gate electrode 7G is connected to the scanning line 3.

In this case, an image signal having image information is applied to the signal line 4, and a scanning drive voltage is applied to the scanning line 5 in synchronization with the image signal. The image information supplied through the signal line 4 is transmitted to the pixel electrode and the comb-shaped pixel electrode (not shown in FIG. 5) through the thin film transistor 7 turned on by the scanning drive voltage, and A liquid crystal layer (not shown in FIG. 5) is driven by a parallel electric field formed between the liquid crystal layer and the common electrode (not shown in FIG. 5).

The image information written to the pixel electrode when the thin film transistor 7 is turned on is stored as charges in the auxiliary capacitance 18 and the liquid crystal capacitance 22 when the thin film transistor 7 changes from on to off. The charges stored in the auxiliary capacitance 18 and the liquid crystal capacitance 22 are held until the thin film transistor 7 is turned on again in the next cycle.

Next, FIGS. 6A, 6B and 6C show the comb-shaped common electrode, the comb-shaped pixel electrode and the scanning in the first embodiment shown in FIGS. FIG. 3 is a partial configuration diagram showing an example of an arrangement relationship with lines, and also shows a state of an electric field formed between them, wherein (a) is a comb-like common electrode and a comb-like pixel electrode; (B) is the state of the electric field formed between the scanning line and the comb-shaped common electrode, and (c) is the state of the electric field formed between the scanning line and the comb-shaped common electrode. FIG. 9 shows a state of an electric field formed between a comb-shaped common electrode and a comb-shaped pixel electrode affected by an electric field.

In FIGS. 6A to 6C, the same components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals.

As shown in FIGS. 6A to 6C,
The comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D are formed so that the electrode width at the tip is wider than the electrode width at the other portions, specifically, from a normal electrode width to a wider electrode width. The comb-shaped common electrode 5 is formed so as to move through the tapered portion.
The distance between D and the tip of the comb-shaped pixel electrode 6D is smaller than the distance between portions other than the tip.

In the above configuration, as shown in FIG. 6A, an electric field E indicated by an arrow is generated in the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D, and the liquid crystal layer is driven by the electric field E. Is done. If the electric field E is not affected by an external electric field, the electric field E is applied to the comb-shaped common electrode 5D and the comb-shaped common electrode 5D arranged in parallel in a region between the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D. The electric field E is generated in the direction orthogonal to the tooth-shaped pixel electrode 6D, and the electric field E at the tip of the comb-shaped common electrode 5D and the end of the comb-shaped pixel electrode 6D swells slightly outward. At this time,
Since the portion where the electric field E swells outward is covered with the light shielding layer 13, it does not affect the displayed image at all.

By the way, as shown in FIG.
Since the phase of the drive voltage supplied to the common line (not shown in FIG. 6) of the adjacent pixels is inverted, an electric field E ′ is generated between the scanning line 3 and the comb-like common electrode 5D, and this electric field E ′ is generated. Electric field E '
Are generated in a direction substantially perpendicular to the electric field E generated between the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D.

For this reason, as shown in FIG.
The electric field E generated between the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D is affected by the electric field E ′ generated between the scanning line 5 and the comb-shaped common electrode 5D. Common electrode 5
Since the distance between D and the tip of the comb-shaped pixel electrode 6D is narrowed, the electric field E affected by the electric field E 'is limited to the electric field E generated in the narrowed region, Is not disturbed. Then, by covering the region in which the interval between the tips between the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D is narrowed with the light shielding layer 13, it is possible to cover all the regions where the electric field E is disturbed. Therefore, the display image is not affected by the disturbance of the electric field E, the contrast of the display image is improved, and a good display image can be obtained.

FIGS. 7 (a), (b), (c),
FIG. 6D is a partial configuration diagram illustrating different examples of the arrangement relationship between the comb-shaped common electrode, the comb-shaped pixel electrode, and the scanning line in the first embodiment illustrated in FIGS. 1 to 5. And the state of the electric field formed between them.

In FIGS. 7A to 7D, the same components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals.

Comb-shaped common electrode 5D and comb-shaped pixel electrode 6D
FIG. 7 shows the shape shown in FIGS.
As shown in (a), both side edges of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D are tapered outwardly,
As shown in FIG. 7 (b), a wide portion is formed at the tip, and a comb-shaped common electrode 5D and a comb-shaped pixel electrode 6 are formed.
D, both side edges are tapered outwardly to form a wide portion at the tip, and the distance between the comb-like common electrode 5D and the scanning line 3 is greater than the distance between the comb-like pixel electrode 6D and the scanning line 3. Are arranged so that the interval between them becomes narrow, FIG. 7 (c)
As shown in FIG. 5, the width of the comb-shaped common electrode 5D is unchanged, and both side edges of the comb-shaped pixel electrode 6D are rapidly expanded outward in a tapered shape to form a large wide portion at the tip end. As shown in FIG. 7 (d), both side edges of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D are tapered outwardly to form a wide portion at the front end and a comb-shaped shape. The portion of the common electrode 5D opposed to the scanning line 3 and the portion of the comb-shaped pixel electrode 6D opposed to the scanning line 3 may have a shape such that the central portion is slightly recessed. 7A to 7D, any of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D illustrated in FIGS. 7A to 7D is illustrated in FIGS. Functions equivalent to the functions achieved by the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D can be achieved.

In each of the above examples, the width between the normal width portion and the wide width portion is tapered in order to widen the tip portions of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D. Is provided to prevent disclination.

FIG. 8 is a configuration diagram showing a second embodiment of the lateral electric field type active matrix liquid crystal display device according to the present invention, and the left side shows a liquid crystal drive section constituting four adjacent pixels. FIG. 3 is a plan view, and the right side is a plan view showing a state in which a light shielding layer is overlaid on the same pixel.

In FIG. 8, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

Comparing the second embodiment with the first embodiment, the configuration of the second embodiment is different from the first embodiment in that the common line 5 and the pixel electrode 6 are close to the scanning line 3 on the preceding stage, respectively. The first embodiment differs from the first embodiment in that the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D are arranged in a comb shape only in one direction of the common line 5 and the pixel electrode 6. Although the configuration is different, the other configuration is the same as that of the first embodiment. For this reason, further description of the configuration of the second embodiment will be omitted.

The operation of the second embodiment is similar to that of the first embodiment, since the configuration of the second embodiment is similar to that of the first embodiment. Almost the same as Therefore, further description of the operation of the second embodiment will be omitted.

As described above, according to the second embodiment,
Since only a half of the region in which the interval between the tips of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D is narrowed compared to the first embodiment is required, the aperture ratio is increased accordingly. This makes it possible to improve the contrast of the display image and obtain a good display image, as in the first embodiment.

In this case, also in the second embodiment,
The shape of the tip portions of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D may be any of those illustrated in FIGS. 6A to 6C or FIGS. 7A to 7D. What is shown is used.

FIG. 9 is a block diagram showing a third embodiment of a lateral electric field type active matrix liquid crystal display device according to the present invention. The left side shows a liquid crystal drive section constituting four adjacent pixels. It is a plan view, the right side is a plan view showing a state in which a light-shielding layer is overlaid on the same pixel, and the middle is A
It is sectional drawing which shows the cross-sectional structure of the -A 'line part.

In FIG. 9, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

Comparing the third embodiment with the first embodiment, the configuration of the third embodiment is as follows. The scanning line 3, the common line 5, the comb-shaped common electrode 5D, the pixel electrode 6 and the comb-shaped pixel electrode 6D are formed and arranged on different layers, respectively, and the tips of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D are extended to the scanning line 3 and Although the configuration is different from that of the first embodiment in that the interval between the tip portions of the common electrode 5D and the comb-shaped pixel electrode 6D is the same as the interval between the other portions, the other configuration is different. The configuration is the same as in the first embodiment. Therefore, further description of the configuration of the third embodiment will be omitted.

The operation of the third embodiment is essentially the same as the operation of the first embodiment. In this case, the third embodiment is different from the first embodiment in that the interval between the tip portions of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D is the same as the interval between the other portions. In this case, the electric field E is slightly larger than the electric field E generated in the same portion. However, in the third embodiment, since the tip portions of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D are extended to the scanning line 3, the portion where the electric field E is disturbed is formed by the light shielding layer 13. , And the portion that causes display unevenness is not displayed. Therefore, also in the third embodiment, as in the first embodiment, the contrast of the display image is improved, and a good display image can be obtained.

In this case, instead of disposing the tips of the comb-shaped common electrode 5D and the comb-shaped pixel electrode 6D so as to extend over the scanning line 3, the tips are extended so as to approach the scanning line 3. It may be.

As described above, in each of the first to third embodiments, by using the drive voltage whose phase is inverted every other common line 5, a bright image having excellent viewing angle characteristics is obtained. Even when a display is performed, the contrast can be improved without being affected by the drive voltage.

In each of the first to third embodiments, each of the common lines 5 is driven at a different phase, and the common line 5 between the adjacent common lines 5 is almost common for most of the time. It is needless to say that the display voltage is improved so as to improve the contrast of the display image and obtain a good display image by driving the polarity to be opposite to the center voltage.

[0057]

As described above, according to the first aspect of the present invention, at least one of the comb-shaped pixel electrode connected to the pixel electrode and the comb-shaped common electrode connected to the common line is connected. Construct so that the width of the tip is wider than the other parts,
Since the interval between the comb-shaped pixel electrode and the tip portion of the comb-shaped common electrode is made smaller than the interval between the other portions, the gap between the comb-shaped pixel electrode and the tip portion of the comb-shaped common electrode is narrow. The disturbance rate of the electric field formed in the interval region can be extremely reduced, and as a result, there is an effect that a good display image can be obtained without lowering the contrast of the display image.

According to the second aspect of the present invention, the scanning line, the common line, and the comb-like common electrode are stacked and arranged via the insulating layer, and the comb-like pixel electrode connected to the pixel electrode is provided. In addition, since each end portion of the comb-shaped common electrode connected to the common line is arranged to extend below the light-shielding layer, it is formed between the comb-shaped pixel electrode and each end portion of the comb-shaped common electrode. It is possible to cover the display image in the area affected by the disturbed electric field with the light shielding layer, and as a result, it is possible to obtain a good display image without lowering the contrast of the display image. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a lateral electric field type active matrix liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional configuration view taken along line AA ′ of the lateral electric field type active matrix liquid crystal display device shown in FIG.

FIG. 3 is a cross-sectional configuration view taken along line BB ′ of the horizontal electric field type active matrix liquid crystal display device shown in FIG. 1;

FIG. 4 is a cross-sectional configuration view taken along line CC ′ of the lateral electric field type active matrix liquid crystal display device shown in FIG.

FIG. 5 is a circuit diagram showing an example of an equivalent circuit in the lateral electric field type active matrix liquid crystal display device shown in FIG.

FIG. 6 is a partial configuration diagram illustrating an example of an arrangement relationship among a comb-shaped common electrode, a comb-shaped pixel electrode, and a scanning line in the first embodiment illustrated in FIGS. 1 to 5;

FIG. 7 is a partial configuration diagram showing different examples of the arrangement relationship between a comb-shaped common electrode, a comb-shaped pixel electrode, and a scanning line in the first embodiment shown in FIGS. 1 to 5;

FIG. 8 is a configuration diagram showing a second embodiment of the lateral electric field type active matrix liquid crystal display device according to the present invention.

FIG. 9 is a configuration diagram showing a third embodiment of a lateral electric field type active matrix liquid crystal display device according to the present invention.

FIG. 10 is a partial configuration diagram showing an example of an arrangement relationship among a comb-shaped common electrode, a comb-shaped pixel electrode, and a scanning line in a known horizontal electric field type active matrix liquid crystal display device.

[Explanation of symbols]

 1 First transparent substrate 22 is a liquid crystal capacitor 2 Second transparent substrate 3 Scanning line 4 Signal line 5 Common line 5D Comb-like common electrode 6 Pixel electrode 6D Comb-like pixel electrode 7 Thin film transistor (TFT) 7G Gate electrode 7D Drain electrode 7S Source electrode 7H Semiconductor layer 7C Ohmic contact layer 8 Liquid crystal layer 9 Insulating layer 10 Protective layer 11 First polarizing plate 12 First alignment film 13 Light shielding layer (black matrix) 14 Color filter 15 Flattening resin film 16 Second polarized light Plate 17 Second alignment film 18 Auxiliary capacitance 19 Scan electrode drive circuit 20 Signal electrode drive circuit 21 Common electrode drive circuit 22 Liquid crystal capacitance

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shin Yoneya 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Makoto Tsumura 7-1, Omikamachi, Hitachi City, Ibaraki Prefecture No. 1 F term in Hitachi Research Laboratory, Hitachi Ltd. (reference) 2H090 HA03 HC11 HC12 KA18 LA04 MB14 2H092 GA14 JA26 JA29 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB38 JB58 JB64 JB69 KA05 KA07 MA13 MA17 MA27 MA35 MA37 MA06 PA06 QA18

Claims (4)

[Claims] A first liquid crystal layer sandwiched between the first and second transparent substrates; a liquid crystal driving unit formed on the first transparent substrate; A liquid crystal display device that drives the liquid crystal layer by a parallel electric field formed by a driving unit, wherein the liquid crystal driving unit includes a plurality of scanning lines and a plurality of signal lines that are arranged in a matrix in an insulated state. A plurality of active elements disposed at each intersection of the plurality of scanning lines and the plurality of signal lines, and disposed at a portion surrounded by the plurality of scanning lines and the plurality of signal lines, A plurality of pixel electrodes connected to the plurality of active elements and forming a plurality of comb-shaped pixel electrodes, respectively, arranged in parallel with the plurality of scanning lines, and insulated from the plurality of pixel electrodes; Together with multiple A plurality of common lines forming a comb-shaped common electrode, wherein the adjacent common lines operate in different phases, and the plurality of comb-shaped pixel electrodes and the plurality of comb-shaped The liquid crystal display device according to claim 1, wherein the common electrode is formed such that an interval between a tip portion facing the scanning line is smaller than an interval between other portions. 2. The liquid crystal device comprising: first and second transparent substrates; a liquid crystal layer sandwiched between the first and second transparent substrates; and a liquid crystal driving unit formed on the first transparent substrate. A liquid crystal display device that drives the liquid crystal layer by a parallel electric field formed by a driving unit, wherein the liquid crystal driving unit includes a plurality of scanning lines and a plurality of signal lines that are arranged in a matrix in an insulated state. A plurality of active elements disposed at each intersection of the plurality of scanning lines and the plurality of signal lines, and disposed at a portion surrounded by the plurality of scanning lines and the plurality of signal lines, A plurality of pixel electrodes connected to the plurality of active elements and forming a plurality of comb-shaped pixel electrodes, respectively, arranged in parallel with the plurality of scanning lines, and insulated from the plurality of pixel electrodes; Together with multiple A plurality of common lines forming a comb-shaped common electrode, wherein the adjacent common lines each operate at a different phase, and each of the scanning lines and each of the common lines and each of the comb-shaped common electrodes The electrodes are stacked and arranged via an insulating layer, and the tips of the plurality of comb-shaped pixel electrodes and the plurality of comb-shaped common electrodes are arranged so as to overlap or approach the scanning line, and A liquid crystal display device, wherein the liquid crystal display device is arranged so as to overlap with a light shielding layer. 3. The liquid crystal display device according to claim 1, wherein the common line is driven by inverting alternating current for every one screen period of display. 4. The common line, wherein an end of the common line is arranged close to a preceding scanning line in a pixel.
Or the liquid crystal display device according to 3.