JP4018911B2 - Transflective color liquid crystal display element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transflective color liquid crystal display element having a light transmitting portion and a light reflecting portion on the inner surface of a cell. More specifically, the invention achieves both low power consumption of liquid crystal driving power and transmission luminance and transmitted color reproducibility. It is related to the technology to be aimed at.
[0002]
[Prior art]
The transflective color liquid crystal display element has a combined function of a reflection type and a transmission type, and in order to obtain a bright display even in a dark environment, as shown in FIG. A backlight BL is provided on the surface side.
[0003]
The liquid crystal cell 10 is formed by pressure-bonding a first transparent substrate (F plate) 11 on the display observation surface side and a second transparent substrate (R plate) 12 on the counter display observation surface side via a peripheral sealing material 13. In the cell, there is provided light transflective means 14 for reflecting external light incident from the display observation surface side and transmitting light from the backlight BL.
[0004]
The light semi-transmissive reflecting means 14 is disposed on the second transparent substrate 12 side. In this example, a light diffusion layer 15 having a fine uneven surface is formed on the inner surface of the second transparent substrate 12, and the light semi-transmissive is formed thereon. Reflecting means 14 is provided. For the light transflective means 14, for example, a metal thin film (half mirror) such as aluminum or a complete reflective film (slit mirror or perforated mirror) having a large number of openings as a light transmitting portion is used.
[0005]
A color filter 16 is formed on the light transflective means 14, and a liquid crystal driving electrode 18 is provided on the color filter 16 via an electric insulating film (flattening film) 17. An alignment film 19 is formed on the liquid crystal drive electrode 18. The color filter 16 may be provided on the first transparent substrate 11 side.
[0006]
On the first transparent substrate 11 side, a liquid crystal driving electrode 21 as a counter electrode of the liquid crystal driving electrode 18 is provided, and an alignment film 23 is formed thereon with an electric insulating film 22 interposed therebetween. Although not shown, a predetermined liquid crystal substance is sealed between the alignment films 19 and 23. A phase difference plate 24 and a polarizing plate 25 are attached to the outer surfaces of the first and second transparent substrates 11 and 12, respectively.
[0007]
By the way, in the case of full dot matrix display, one of the liquid crystal drive electrodes 18 and 21 is a striped common electrode, and the other is a striped segment electrode wired so as to be orthogonal to the common electrode. However, conventionally, the liquid crystal drive electrode 18 on the second transparent substrate 12 side is a common electrode (scanning electrode), and the liquid crystal drive electrode 21 on the first transparent substrate 11 side is a segment electrode (signal electrode).
[0008]
In this example, a terminal portion 11a is provided on the first transparent substrate 11 side, and a predetermined drive voltage is applied to the common electrode 18 from the terminal portion 11a via a transfer material included in the peripheral sealing material 13. Is fed to the common electrode 18.
[0009]
[Problems to be solved by the invention]
However, conventionally, since the common electrode 18 and the metal film constituting the light transflective means 14 are both formed on the same substrate (second transparent substrate 12) side, the following problems arise.
[0010]
Usually, a driving voltage of about 10 to 20 V is alternately applied to the common electrode 18 in a line sequential manner. On the other hand, the applied voltage to the segment electrode 21 is about 3 to 5 V, and the drive voltage is applied to the selected segment electrodes all at once.
[0011]
Here, referring to FIG. 7, it is assumed that among the three common electrodes 18 a to 18 c illustrated, for example, the central common electrode 18 b is a selection electrode, and the common electrodes 18 a and 18 c adjacent thereto are non-selection electrodes. Since the metal film of the light transflective means 14 exists on the back side of the common electrode 18 via the electric insulating film (dielectric) 17, the metal film is interposed between the common electrode 18b and the common electrodes 18a and 18c. As a result, capacitive coupling occurs.
[0012]
For this reason, the load capacity with respect to the common electrode 18a which is a selection electrode becomes large, and power consumption increases correspondingly. For example, assuming that the voltage required to drive the liquid crystal with the counter electrode is normally 10 V, if the load capacitance increases due to the capacitive coupling, a higher driving voltage must be applied. This phenomenon is particularly noticeable when an aluminum thin film (half mirror) having no opening is used as the light transflective film, and the power consumption is increased by about 40% at the maximum.
[0013]
If, for example, a slit mirror in which an opening (light transmission part) is provided in the complete reflection film is adopted as the light semi-transmissive reflection means 14, the capacitive coupling becomes weaker than in the case of the half mirror, but the power source is particularly used for the battery. The mobile phones that are demanded are not sufficient for reducing power consumption. In addition, the slit mirror has another problem that it is difficult to achieve both good transmission luminance and good transmission color.
[0014]
The present invention has been made to solve the above-mentioned problems, and a first object thereof is to reduce the consumption of liquid crystal driving power. In addition, a second object of the present invention is to achieve both the transmission luminance and the transmission color reproducibility and increase the contrast.
[0015]
[Means for Solving the Problems]
In order to achieve the first object, the present invention provides a liquid crystal cell formed by pressure-bonding a first transparent substrate on the display observation surface side and a second transparent substrate on the non-display observation surface side through a peripheral sealing material; A backlight disposed on the side opposite to the viewing side of the liquid crystal cell, a stripe-shaped common electrode is formed on one of the transparent substrates, and a stripe-shaped perpendicular electrode to the common electrode is formed on the other A segment electrode is formed, and a light semi-transmission made of a metal film that transmits light from the backlight to the inner surface of the second transparent substrate and reflects external light incident from the first transparent substrate side. a reflecting means, in the transflective color liquid crystal display device having a color filter formed on the light semi-transmissive reflecting means, on the second transparent substrate provided with the light semi-transmissive reflecting means, the segment electrodes Serial disposed through an electrically insulating film on the color filter, the and the common electrode is arranged on the first transparent substrate side, the light which the light semi-transmissive reflecting means is formed of an opening for transmitting light from the backlight A light reflecting portion comprising a transmissive portion and a completely reflective film, the light transmissive portion and the light reflecting portion comprising a slit mirror formed in a stripe shape in parallel with the segment electrode, and the light reflection of the slit mirror A part of the portion is disposed across the adjacent segment electrodes, and a black mask is formed on the light reflecting portion to prevent light leakage of the backlight light from between the segment electrodes. It is a feature.
[0016]
Even if the segment electrode and the metal film of the transflective means are formed on the same substrate side instead of the common electrode, capacitive coupling occurs between adjacent segment electrodes via the metal film. Since the applied voltage is about 1/3 to 1/4 compared to the common electrode, lower power consumption can be achieved compared to the conventional example.
[0017]
In the case of segment electrodes, a signal voltage may be applied to adjacent segment electrodes at the same time. In this case, capacitive coupling does not occur between the adjacent segment electrodes, thus further reducing power consumption. Can be expected.
[0018]
In the present invention, the light transmission part and the light reflection part are assigned to each sub-pixel of the color filter, and a black mask (light-shielding) is provided between the sub-pixels so as to correspond to the segment electrodes. By disposing the film, light leakage from between the segment electrodes can be prevented.
[0019]
When the appearance of the transmitted light is emphasized and the aperture ratio of the light transmitting portion is set to 50% or more, for example, it is preferable to dispose the black mask on the light reflecting portion. According to this, even when a misalignment or an increase in the line width occurs when forming a black mask, the aperture ratio of the light transmission portion is not affected, and the designed aperture ratio can be maintained. It becomes possible.
[0020]
In order to achieve the second object (coexistence of transmission luminance and transmitted color reproducibility and high contrast), in the present invention, the light reflecting part is a silver-based complete reflecting film, and the opening of the light transmitting part is provided. The rate is 30% or more. Further, it is preferable that the color filter of the light transmitting portion has a color area of 40 or more and the color filter of the light reflecting portion has a color area of 15 or less. Here, the color area is a value obtained by plotting R, G, and B color filters on CIE chromaticity coordinates and multiplying the area value of a region surrounded by three points by 1000.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention. In the liquid crystal cell 10A provided in the transflective color liquid crystal display element of the present invention, a light transflective means 14 is formed. A segment electrode 21 (see FIG. 2B) is provided on the second transparent substrate 12 side, and a common electrode 18 (see FIG. 2A) is provided on the first transparent substrate 11 side.
[0022]
Therefore, the segment electrode 21 is connected to a predetermined lead electrode of the terminal portion 11a through the transfer material included in the peripheral sealing material 13, but the other configuration will be described with reference to FIG. It may be the same as the conventional example. Note that the common electrode 18 and the segment electrode 21 may be directly drawn out to the terminal portions of the respective substrates without using a transfer material.
[0023]
By disposing the segment electrode 21 on the second transparent substrate 12 side as in the first embodiment, power consumption can be significantly reduced as compared with the conventional example. That is, as described above, the applied voltage to the segment electrode 21 is usually about 3 to 5 V, which is about 1/3 to 1/4 compared to the applied voltage to the common electrode (about 10 to 20 V).
[0024]
Therefore, even if the capacitive coupling occurs between the adjacent segment electrodes through the metal film of the light transflective reflection means 14 and the load capacity increases, the applied voltage is low and the capacitive coupling force is weak in the first place. Therefore, a voltage that is set higher than the applied voltage in anticipation of an increase in the load capacity is small.
[0025]
In the full dot matrix display, on the segment electrode 21 side, there is a relatively high probability that a signal voltage is simultaneously applied to adjacent segment electrodes. In this case, capacitive coupling occurs between adjacent segment electrodes. Therefore, further reduction in power consumption can be expected.
[0026]
The metal film constituting the light transflective means 14 may be any of a half mirror, a perforated mirror, and a slit mirror. However, in order to further reduce power consumption, the capacitance coupling force A slit mirror that can weaken is preferred. FIG. 2C schematically shows an example of a slit mirror.
[0027]
The slit mirror 140 is formed by forming a plurality of light transmission parts 141 each having a slit-like opening having a predetermined width that transmits light from the backlight BL on a metal film in parallel with each other at a predetermined interval. The metal film portion left between 141 functions as the light reflecting portion 142. The material is preferably a silver-based fully reflective film with good reflection efficiency.
[0028]
On the second transparent substrate 12, a light diffusion layer 15, a slit mirror 140, a color filter 16, an electrical insulating film (planarizing film) 17, a segment electrode 21 and an alignment film 19 are formed in this order. The light transmitting portion 141 and the light reflecting portion 142 of the slit mirror 140 are arranged in parallel.
[0029]
Here, the positional relationship between the slit mirror 140, the color filter 16, and the segment electrode 21 and the black mask (light-shielding film) 30 are shown in FIG. The arrangement will be described. FIGS. 3A and 3B are reference examples of the present invention.
[0030]
One pixel (pixel) of the color liquid crystal display element is composed of a set of R, G, and B. Each unit of R, G, and B is a sub-pixel (sub-pixel) SP, and each sub-pixel SP is a segment electrode 21. One line width W is arranged at a position corresponding to each segment electrode 21 with substantially the same width.
[0031]
With respect to the slit mirror 140, a light transmitting portion 141 and a light reflecting portion 142 are assigned to each subpixel SP. The widths of the light transmission part 141 and the light reflection part 142 with respect to the subpixel SP are determined relatively. For example, if the area of the sub-pixel SP is 100 and the opening width of the light transmitting portion 141 is 30%, the width of the light reflecting portion 142 is the remaining 70%.
[0032]
In order to prevent light leakage (light omission) from between the segment electrodes 21, a black mask 30 is disposed between the sub-pixels SP. That is, the black mask 30 is provided at a position corresponding to between the adjacent segment electrodes 21a and 21b between the sub-pixels SP.
[0033]
By the way, in order to make it difficult to generate capacitive coupling between the adjacent segment electrode 21a and the segment electrode 21b via the light reflecting portion (completely reflecting film) 142, as shown in the reference example of FIG. It is preferable not to overlap the reflecting portion 142 with the adjacent segment electrode. In this case, the black mask 30 is disposed so as to fill a part of the light transmission part 141.
[0034]
However, in the case where the appearance of transmitted light is emphasized and the design is made such that the opening width of the light transmitting portion 141 is 0.5 times or more of the segment electrode width W, for example, the main portion of FIG. As shown in the plan view and the cross-sectional view of FIG. 4B, the light reflecting portion 142 is arranged so that a part thereof overlaps the adjacent segment electrode, and the black mask 30 is disposed on the light reflecting portion 142. It is preferable to install.
[0035]
The reason is that when the black mask 30 is formed, the black mask may be misaligned or the black mask line width may be increased. In this case, the aperture ratio of the light transmitting portion 141 is different from the design value in the example of FIG. Because it becomes a thing. In this regard, according to the example of the present invention of FIG. 4, the aperture ratio of the light transmitting portion 141 changes from the design value even when the black mask is misaligned or the black mask line width is increased during the black mask formation. There is no fear.
[0036]
In this way, the black mask 30 is provided for each sub-pixel SP. The black mask 30 is formed not only between the segment electrodes 21 but also at a position corresponding to between the common electrodes 18.
[0037]
This will be described with reference to FIG. 5. A black mask 30 (S) between the segment electrodes and a common electrode so as to surround the R, G, B sub-pixels SP (R), SP (G), SP (B). The interposing black mask 30 (C) is formed in a lattice pattern. Incidentally, if the electrode width of the common electrode 18 is 240 μm, the electrode width of the segment electrode 21 is set to 80 μm, which is 1/3 of the electrode width.
[0038]
Next, as a second embodiment of the present invention, in the case where the slit mirror 140 is used for the transflective means 14, a description will be given of suitable conditions for achieving both high transmission contrast and transmissive color reproducibility and high contrast. To do.
[0039]
As the slit mirror 140, a silver-based (preferably Ag—Pd-based) complete reflection film with good reflection efficiency is used. The opening area of the light transmission part 141 is preferably 30% or more (particularly 50 to 80%). The slit mirror 140 is parallel to the segment electrode 21.
[0040]
In each of the subpixels SP (R), SP (G), and SP (B), a color filter is separately applied to the light transmitting portion 141 and the light reflecting portion 142. That is, a 6-color RGB resist is used. For example, V259 (film thickness: 1.0 μm) manufactured by Nippon Steel Chemical Co., Ltd. is applied to the light transmitting portion 141, and 0404 (film thickness: 1.0 μm) manufactured by Mitsubishi Chemical Corporation is applied to the light reflecting portion 142.
[0041]
The color filter of the light transmitting portion 141 has a Y value <50 and a color area> 40 (preferably, a Y value <45 and a color area> 50) in transparent white display. The color filter of the light reflecting portion 142 has a Y value> 55 in transparent white display and a color area <15 (preferably, a Y value> 60 and a color area <10).
[0042]
Assuming that the electrode width of the common electrode 18 is 240 μm and the electrode width of the segment electrode 21 is 80 μm, the line width of the black mask 30 (S) on the segment electrode side is 13 μm, and the line width of the black mask 30 (C) on the common electrode side The width is 20 μm.
[0043]
【The invention's effect】
As described above, according to the present invention, the liquid crystal cell includes light transflective means made of a metal film that transmits light from the backlight and reflects external light incident from the display observation surface side. In a full dot matrix display transflective color liquid crystal display element in which a color filter is formed on the light transflective means, a segment electrode is disposed on one transparent substrate side provided with the light transflective means, and the other By disposing the common electrode on the transparent substrate side, the liquid crystal driving power can be reduced.
[0044]
In the case where a slit mirror is used for the light transflective means, the light reflecting portion is a silver-based completely reflecting film, the aperture ratio of the light transmitting portion is 30% or more, and the color filter of the light transmitting portion is a color area. Is 40 or more, and the color filter of the light reflection portion has a color area of 15 or less, it is possible to achieve both transmission luminance and transmission color reproducibility and high contrast.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing the internal structure of a transflective color liquid crystal display device according to the present invention.
FIG. 2 is a plan view showing each of a common electrode, a segment electrode, and a slit mirror provided in a liquid crystal cell provided in the present invention.
FIG. 3 is an enlarged plan view of a main part and a cross-sectional view thereof for explaining the positional relationship between the segment electrode, the slit mirror, and the color filter, and the arrangement of the black mask.
FIG. 4 is an enlarged plan view of a main part for explaining another arrangement of the black mask and a cross-sectional view thereof.
FIG. 5 is a plan view for explaining a segment electrode side black mask and a common electrode side black mask. FIG. 6 is a schematic sectional view showing an internal structure of a transflective color liquid crystal display element as a conventional example.
FIG. 7 is a schematic diagram for explaining capacitive coupling that occurs between adjacent electrodes.
[Explanation of symbols]
10A Liquid crystal cell 11 1st transparent substrate (display observation surface side transparent substrate)
12 Second transparent substrate (transparent substrate on the non-display viewing side)
DESCRIPTION OF SYMBOLS 13 Peripheral sealing material 14 Light transflective means 140 Slit mirror 141 Light transmissive part 142 Light reflective part 15 Light diffusion layer 16 Color filter 17, 22 Electrical insulating film 18 Common electrode 19, 23 Orientation film 21 Segment electrode 30 Black mask BL Back Light SP Subpixel

Claims (2)

A liquid crystal cell formed by pressure-bonding a first transparent substrate on the display observation surface side and a second transparent substrate on the counter display observation surface side through a peripheral sealing material, and a back disposed on the counter display observation surface side of the liquid crystal cell A stripe-shaped common electrode is formed on one of the transparent substrates, and a stripe-shaped segment electrode orthogonal to the common electrode is formed on the other transparent substrate, and the second transparent substrate A light transflective means made of a metal film that transmits light from the backlight and reflects external light incident from the first transparent substrate side, and a color is provided on the light transflective means. In a transflective color liquid crystal display element in which a filter is formed,
On the second transparent substrate provided with the light semi-transmissive reflecting means, the segment electrodes are arranged via an electrically insulating film on the color filter, and the common electrode is disposed on said first transparent substrate,
The light transflective means has a light transmissive portion comprising an opening for transmitting light from the backlight and a light reflective portion comprising a completely reflective film, and the light transmissive portion and the light reflective portion are parallel to the segment electrode. Consists of slit mirrors formed in stripes,
A black mask in which a part of the light reflecting portion of the slit mirror is disposed across the adjacent segment electrodes and prevents light leakage of the backlight light from between the segment electrodes on the light reflecting portion. A transflective color liquid crystal display element, wherein: It becomes the light-reflecting portion is silver-based fully reflective film, a semi-transmissive color liquid crystal display device according to claim 1, wherein the aperture ratio of the light-transmitting portion is 30% or more.

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