JP6593161B2 - Liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device using a polymer dispersed liquid crystal in a liquid crystal layer.

  As a liquid crystal panel that does not require a polarizing plate to control the amount of light transmission, for example, a polymer dispersed liquid crystal such as a polymer network (hereinafter abbreviated as PN) liquid crystal as disclosed in Patent Document 1 is used as a liquid crystal panel. The liquid crystal panel used for the layer is drawing attention.

  When a plurality of segments are provided on the liquid crystal panel, a plurality of segment electrodes as display electrodes are arranged in the display area of the lower glass substrate. And an upper glass substrate and a lower glass substrate are arrange | positioned so that these segment electrodes may oppose in common with respect to one common electrode formed in solid shape on the upper glass substrate.

  Each of the plurality of segment electrodes is formed so that the potential can be set individually. The liquid crystal layer in a region corresponding to one segment electrode is made one segment, and the voltage applied to the liquid crystal layer is controlled for each segment.

  When a plurality of segments are provided in this way and a PN liquid crystal is used for the liquid crystal layer, the gap set for physically separating the two adjacent segment electrodes is a cloudy area that is not driven, that is, dark on the display. There has been a problem that it is visually recognized as a region.

  Therefore, even when PN liquid crystal is used for the liquid crystal layer, a technique that can prevent the gap between two adjacent segment electrodes from being visually recognized as a dark region has been proposed. (For example, Patent Document 1)

Japanese Patent No. 5505442

  The technique described in the said patent document is demonstrated using FIG. This figure shows an example of the structure of a part of a liquid crystal panel using a polymer-dispersed liquid crystal as a liquid crystal layer. FIG. 7 (A) is a partial plan view, and FIG. 7 (B) is FIG. It is sectional drawing along line '.

  Note that the rectangular marker P shown in FIG. 7 is a character electrode 22a that is a rectangular frame-shaped segment electrode 22 indicating a focus area in a liquid crystal panel used in a viewfinder of a single-lens reflex camera, for example. A non-character electrode 22b that is a segment electrode is provided inside and outside the frame of the electrode 22a via a gap 22s. In an actual liquid crystal panel, a plurality of, for example, 30 to 50 markers P are arranged, and any one of them is selectively displayed to display a focused position in the subject image. The non-character electrode 22b is for maintaining the background area transparent even when the character electrode 22a is displayed.

  The cross-sectional configuration includes a first substrate 21 made of a transparent insulating material such as glass, and a second substrate 23 also made of a transparent insulating material such as glass. In the display area on the first substrate 21, a conductive film made of a transparent conductive material such as ITO (indium tin oxide) is patterned as a plurality of segment electrodes 22, and the character electrodes 22 a are formed by the segment electrodes 22. And the non-character electrode 22b is comprised.

  On the lower layer side of the segment electrode 22, a lower layer wiring 27 routed to set a potential at the segment electrode 22 and an auxiliary wiring 29 described later in detail are provided. That is, on the first substrate 21, for example, a lower layer wiring 27 and an auxiliary wiring 29 in which a conductive film made of a transparent conductive material such as ITO is patterned are provided as a second layer. On this second layer, an insulating film 30 made of a transparent insulating material such as silicon nitride is provided as a third layer. And the segment electrode 22 mentioned above is provided as a 1st layer on this 3rd layer.

  On the other hand, a conductive film made of a transparent conductive material such as ITO is provided as a common electrode 24 on the second substrate 23. Then, the second substrate 23 is arranged such that each of the plurality of segment electrodes 22 in the first substrate 21 faces the common electrode 24 and has a predetermined interval with the first substrate 21. It is bonded to the first substrate 21 via a gap material (not shown).

  A gap between the first substrate 21 and the second substrate 23 is provided as a liquid crystal layer 28. The liquid crystal layer 28 is configured by sealing PN liquid crystal as polymer dispersed liquid crystal in which liquid crystal molecules having positive dielectric anisotropy are dispersed in PN in a gap between substrates. The dielectric anisotropy of the liquid crystal molecules dispersed in PN is not limited to positive, and may be negative.

  In this liquid crystal panel, the liquid crystal layer 28 in the region corresponding to the character electrode 22a is controlled to be clouded (light scattering state), and the liquid crystal layer 28 in the region corresponding to the non-character electrode 22b is in a transparent state (light non-diffusing state). By controlling to, display is performed so that information overlaps the subject image in the viewfinder.

  Therefore, the character electrode 22a is disposed so as to be adjacent to the non-character electrode 22b in principle. In other words, the segment electrode 22 has a character electrode 22a formed in a positive pattern and a non-character electrode 22b formed in a negative pattern in association with information displayed in the display area of the liquid crystal panel.

  Each of the plurality of character electrodes 22 a is connected to the lower layer wiring 27 through a first contact hole 31 provided in the insulating film 30. Each of the plurality of non-character electrodes 22 b is connected to the auxiliary wiring 29 through a second contact hole 32 provided in the insulating film 30.

  Each of the plurality of character electrodes 22a is connected to a different lower layer wiring 27 so that the potential can be individually set. On the other hand, each of the plurality of non-character electrodes 22b is commonly connected via the auxiliary wiring 29 so that the potentials of the non-character electrodes 22b become equal to each other.

  Accordingly, in the entire liquid crystal panel, one segment made of PN liquid crystal is formed for each character electrode 22a, and only one segment corresponding to the character electrode 22a is formed.

  The auxiliary wiring 29 has a connection wiring 29x and an auxiliary electrode 29y. The connection wiring 29x connects the plurality of non-character electrodes 22b to each other. One auxiliary electrode 29y extends along a gap 22s between adjacent segment electrodes 22, and is arranged so as to close the gap 22s in a plan view of the liquid crystal panel.

  The auxiliary electrode 29y has a floating structure by being separated from the connection wiring 29x. Further, the auxiliary electrode 29y is larger than the gap 22s so that the overlap width W2 between the auxiliary electrode 29y and the non-character electrode 22b is larger than the overlap width W1 between the auxiliary electrode 29y and the character electrode 22a. Widely formed.

  That is, the auxiliary electrode 29y is formed such that the overlapping area between the auxiliary electrode 29y and the non-character electrode 22b is larger than the overlapping area between the character electrode 22a and the influence of the auxiliary electrode 29y on the potential of the auxiliary electrode 29y. The potential set to the non-character electrode 22b is formed to be larger than the potential set to 22a.

  Therefore, a voltage corresponding to the potential set for the non-character electrode 22b can be applied to the liquid crystal layer 28 corresponding to the gap 22s by the auxiliary electrode 29y. Here, the potential set to the non-character electrode 22b is a potential with which the liquid crystal layer 28 is in a transparent state, and therefore the liquid crystal layer 28 corresponding to the gap 22s regardless of the potential set to the character electrode 22a. Can be controlled in a relatively transparent state.

  However, in the liquid crystal panel having the structure described in the above patent document, there is a problem that electrostatic breakdown frequently occurs at the auxiliary electrode at the time of manufacture, and the yield is extremely deteriorated. In particular, when forming an ITO film having a floating structure as an auxiliary electrode in the gap between electrodes forming a large character, the auxiliary electrode itself is also of a corresponding size, so that static electricity tends to stay, resulting in electrostatic breakdown. It will occur more.

  The present invention has been made in view of the above circumstances, and the object of the present invention is a polymer-dispersed liquid crystal having a structure that prevents a gap between adjacent segment electrodes from being viewed as a dark region. It is another object of the present invention to provide a liquid crystal display device capable of improving yield.

According to one embodiment of the present invention, a liquid crystal layer including a polymer-dispersed liquid crystal provided between a transparent first substrate and a transparent second substrate, and a frame shape formed on the first substrate A transparent first segment electrode is formed on the first substrate as the same first layer as the first segment electrode, and gaps are respectively formed inside and outside the frame-shaped first segment electrode. A transparent second segment electrode that is divided and interposed between the first segment electrode and the second segment electrode, the transparent common electrode that is formed on the second substrate, and that is opposed to the first segment electrode and the second segment electrode, A transparent auxiliary electrode formed on the first substrate in a floating state along the gap between the first segment electrode and the second segment electrode, and the second layer identical to the auxiliary electrode as the second layer. Formed on the substrate of 1, Insulated from the auxiliary electrode and the second segment electrode, connected to the first segment electrode and set to the same potential, and connected to a terminal outside the region of the first segment electrode and the second segment electrode When the transparent lower layer wiring and the liquid crystal layer corresponding to the first segment electrode are in a light scattering state, the potential at the first segment electrode becomes equal to the potential at the common electrode, When the potential at the second segment electrode is set to be different from the potential at the common electrode, and the liquid crystal layer corresponding to the first segment electrode is in a light non-scattering state, the first segment A control circuit that sets both the potential at the electrode and the potential at the second segment electrode to be different from the potential at the common electrode, and the auxiliary electrode has a longitudinal direction thereof. It is formed by dividing at a break in a predetermined pitch for each length, in the second layer remote from the liquid crystal layer than the first layer, than the width of the gap of the first segment electrode and the second segment electrode And the width of the overlap with the second segment electrode is larger than the width of the overlap with the first segment electrode in the width direction .

  According to the present invention, it is possible to improve the yield while adopting a structure that prevents the gap between adjacent segment electrodes from being visually recognized as a dark region in the polymer dispersed liquid crystal.

FIG. 1A is a partial plan view of a liquid crystal panel according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view taken along line I-I ′ of FIG. The figure which extracts and shows the auxiliary electrode of II part of FIG. 1 (A) based on the embodiment. FIG. 3A shows a potential distribution along the gap position of an unbroken auxiliary electrode, FIG. 3A is a partial plan view, and FIG. 3B is a potential in a cross section taken along line III-III ′ of FIG. The figure which shows distribution. FIG. 4A is a partial plan view, and FIG. 4B is a cross section taken along line IV-IV ′ in FIG. 4A. FIG. 4A shows a potential distribution along the gap position of the auxiliary electrode according to the embodiment. FIG. FIG. 5A is a partial plan view, and FIG. 5B is a cross section taken along the line V-V ′ in FIG. 5A. FIG. 5A shows a potential distribution along the gap position of the auxiliary electrode according to the embodiment. FIG. 6 shows an example of specific dimensions of the auxiliary electrode according to the embodiment, FIG. 6A is a plan view showing the configuration of the character electrode and the non-character electrode, and FIG. 6B is a broken line portion of FIG. FIG. 6C is a partial cross-sectional view showing the relationship between the gap and the auxiliary electrode, in which the range of VIa is enlarged, and FIG. 6C is a cross-sectional view taken along the line VIb-VIb ′ of FIG. FIGS. 7A and 7B show a structural example of a liquid crystal panel using polymer dispersed liquid crystal as a liquid crystal layer, FIG. 7A is a partial plan view, and FIG. 7B is a cross section taken along line VII-VII ′ of FIG. Figure.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
1A and 1B show examples of a structure of a part of a liquid crystal panel using a polymer-dispersed liquid crystal as a liquid crystal layer. FIG. 1A is a partial plan view, and FIG. It is sectional drawing along an I 'line.

  The basic configuration itself of the liquid crystal panel is substantially the same as the content shown in FIG. 7, and the same parts are denoted by the same reference numerals and the description thereof is omitted.

  Then, instead of the auxiliary electrode 29y of FIG. 7, the auxiliary electrode 41 is arranged along the gap 22s. As shown in the drawing, the auxiliary electrode 41 has a configuration in which a slit is cut and separated every predetermined pitch.

  The auxiliary electrode 41 is formed wider in the width direction than the gap 22s so that the overlap width W2 between the auxiliary electrode 41 and the non-character electrode 22b is larger than the overlap width W1 between the auxiliary electrode 41 and the character electrode 22a. Has been.

  That is, the auxiliary electrode 41 is formed so that the overlapping area between the auxiliary electrode 41 and the non-character electrode 22b is larger than the overlapping area between the character electrode 22a and the influence of the auxiliary electrode 41 on the potential of the auxiliary electrode 41. The potential set to the non-character electrode 22b is formed to be larger than the potential set to 22a.

  Therefore, a voltage corresponding to the potential set for the non-character electrode 22b can be applied to the liquid crystal layer 28 corresponding to the gap 22s by the auxiliary electrode 41. Here, the potential set to the non-character electrode 22b is a potential with which the liquid crystal layer 28 is in a transparent state, and therefore the liquid crystal layer 28 corresponding to the gap 22s regardless of the potential set to the character electrode 22a. Can be controlled in a relatively transparent state.

  FIG. 2 is a diagram showing the auxiliary electrode 41 in the portion II indicated by the broken line in FIG. Here, across the L-shaped gap 22s, the upper right side is the non-character electrode 22b side, and the lower left side is the character electrode 22a. As described above, the auxiliary electrode 41 is formed wider than the gap 22s so that a larger area overlaps the non-character electrode 22b side.

  Here, an example is shown in which the pitch of the auxiliary electrodes 41 is 150 [μm], the length of the auxiliary electrode 41 itself is 138 [μm], and the interval between cuts is 12 [μm].

3 to 5 show potential distributions when the liquid crystal layer 28 near the break of the auxiliary electrode 41 is driven at 5 [V].
FIG. 3 is a diagram showing a potential distribution along the position of the gap 22s of the auxiliary electrode 29y of FIG. FIG. 3B shows a potential distribution in a cross section along the line III-III ′ in the plan view of FIG. As shown in FIG. 5B, since the auxiliary electrode 29y is continuous without interruption, the potential distribution is extremely flat.

  FIG. 4 is a diagram showing a potential distribution along the position of the gap 22s of the auxiliary electrode 41 in which a cut is formed with the dimensions shown in FIG. FIG. 4B shows a potential distribution in a cross section taken along line IV-IV ′ in the plan view of FIG. As shown in FIG. 5B, no practical inconvenience was observed without causing a shadow of the gap 22s at the cut portion to such an extent that the potential distribution was slightly disturbed even at the cut portion of the auxiliary electrode 41.

  FIG. 5 shows the potential distribution along the position of the gap 22s of the auxiliary electrode 41 having a length of 75 [μm] where 75 [μm], which is 50% of the pitch 150 [μm], is set as a gap interval. FIG. FIG. 5B shows a potential distribution in a cross section along the line V-V ′ in the plan view of FIG. As shown in FIG. 5B, the voltage drop is 1 V or less even at the break portion of the auxiliary electrode 41, and the shadow 22g of the gap is not visually recognized at the break portion, and the display quality can be maintained. .

Assuming that the pitch length of the auxiliary electrode 41 is P and the interval between cuts is t, the voltage distribution including the configurations of FIGS. 4 and 5 is examined. If
0.05 ≦ t / P ≦ 0.5
P ≧ 100 [μm]
Then, the voltage drop between the segment electrodes was 1 [V] or less (in the case of 5 [V] driving), and it was confirmed by experiments that the gap 22s was difficult to be visually recognized.

  FIG. 6 shows an example of specific dimensions of the auxiliary electrode 41. 6A is a plan view showing the structure of the character electrode 22a and the non-character electrode 22b of the marker P, and FIG. 6B is an enlarged view of the gap 22s and the auxiliary electrode in the range of the broken line portion VIa in FIG. FIG. 6C is a cross-sectional view taken along the line VI-VI ′ of FIG. 6B.

  The short side of the rectangular frame-shaped character electrode 22a constituting the marker P is 400 [μm], and the short side of the substantially rectangular non-character electrode 22b disposed adjacent to the inside of the character electrode 22a via the gap 22s. Is 200 [μm].

  As described with reference to FIGS. 2 and 4, the dimensions in the length direction of the auxiliary electrode 41 are the pitch length P: 150 [μm], the gap interval t: 12, and the length of the auxiliary electrode 41: 128 [μm]. .

  On the other hand, in the width direction of the auxiliary electrode 41, when the width of the gap 22s is 3 [μm], the width of the portion where the auxiliary electrode 41 and the character electrode 22a overlap is 2.5 [μm], and the non-character electrode 22b A liquid crystal panel was prototyped with the width of the overlapping portion being 12.7 [μm], and an experiment was conducted.

  As a result, there is little static electricity retention at the auxiliary electrode 41 at the time of manufacture, an improvement in yield can be expected, and shadows due to non-lighting in the gap 22s cannot be visually recognized during display driving.

  As described above in detail, according to the present embodiment, it is possible to improve the yield while adopting a structure that prevents the gap between adjacent segment electrodes from being viewed as a dark region in the polymer dispersed liquid crystal. Become.

  In the above embodiment, the character electrode 22a has a rectangular frame shape. However, the present invention does not limit the shape of the character electrode 22a and the non-character electrode 22b adjacent to the character electrode 22a. Absent.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the functions executed in the above-described embodiments may be combined as appropriate as possible. The above-described embodiment includes various stages, and various inventions can be extracted by an appropriate combination of a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, if the effect is obtained, a configuration from which the constituent requirements are deleted can be extracted as an invention.

21 ... first substrate,
22 ... Segment electrode 22a ... Character electrode,
22b ... non-character electrode,
22s ... Gap,
23 ... second substrate,
24 ... Common electrode,
27 ... lower layer wiring,
28, 28r ... liquid crystal layer,
29 ... auxiliary wiring,
29x ... connection wiring,
29y ... auxiliary electrode,
30: Insulating film,
41 ... auxiliary electrode,
P: Marker.

Claims (3)

A liquid crystal layer made of a polymer dispersed liquid crystal provided between a transparent first substrate and a transparent second substrate;
A transparent first segment electrode formed in a frame shape on the first substrate;
A transparent first layer is formed on the first substrate as the same first layer as the first segment electrode, and is divided and arranged inside and outside the frame-shaped first segment electrode via a gap. Two segment electrodes;
A transparent common electrode formed on the second substrate facing both the first segment electrode and the second segment electrode;
A transparent auxiliary electrode formed on the first substrate in a floating state along the gap between the first segment electrode and the second segment electrode;
Formed on the first substrate as the same second layer as the auxiliary electrode, insulated from the auxiliary electrode and the second segment electrode, connected to the first segment electrode and set to the same potential Transparent lower layer wiring connected to terminals outside the region of the first segment electrode and the second segment electrode;
When the liquid crystal layer corresponding to the first segment electrode is in a light scattering state, the potential at the first segment electrode becomes equal to the potential at the common electrode, and the potential at the second segment electrode is When the potential is set to be different from the potential at the common electrode, and the liquid crystal layer corresponding to the first segment electrode is in a light non-scattering state, the potential at the first segment electrode and the second segment A control circuit for setting the potential at the segment electrodes to be different from the potential at the common electrode,
With
The auxiliary electrode is divided and formed at intervals of a predetermined pitch length in the length direction, and the first segment electrode and the second segment are separated from the liquid crystal layer further than the first layer. The width of the gap between the second segment electrodes is wider than the width of the gap between the second segment electrodes, and the width of the overlap with the second segment electrode is larger than the width of the overlap with the first segment electrode in the width direction. the liquid crystal display device, characterized by that.   The pitch length in the length direction of the auxiliary electrode is P, the interval between cuts is t, and t / P is 0.05 or more and 0.5 or less and P is 100 [μm] or more. 1. A liquid crystal display device according to 1. The auxiliary electrode has a pitch length of 138 [μm] or less and a break when the distance between the liquid crystal layers between the first and second segment electrodes and the common electrode is 4 [μm] to 8 [μm]. 3. The liquid crystal display device according to claim 1, wherein the interval is divided by 12 μm or more.