JP2003228061A - Semi-transmission type color liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption of liquid crystal driving power in a semi-transmission type color liquid crystal display element provided with a light semi-transmissive reflecting means formed from a metallic film in a liquid crystal cell. <P>SOLUTION: In the semi-transmission type liquid crystal display element of a full-dot matrix display provided with the metallic film light semi- transmissive reflecting means 14 for transmitting light from the backlight BL into a liquid crystal cell 10A and also reflecting external light incident from a display viewing surface side, and formed with a color filter 16 on the light semi-transmissive reflecting means 14, a segment electrode 21 is arranged on one transparent substrate 12 side provided with the light semi-transmissive reflecting means 14, and a common electrode 18 is arranged on the other transparent substrate 11 side. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semi-transmissive color liquid crystal display device having a light transmitting portion and a light reflecting portion on the inner surface of a cell, and more specifically, it reduces liquid crystal driving power consumption and transmission brightness and The present invention relates to a technology aiming to achieve both the reproduction of transmitted colors.

[0002]

2. Description of the Related Art A transflective color liquid crystal display device has a composite function of a reflective type and a transmissive 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 side opposite to the display observation surface 10.

The liquid crystal cell 10 includes a first transparent substrate (F plate) 11 on the display observation surface side and a second transparent substrate (R) on the opposite display observation surface side.
The plate 12 and the plate 12 are pressure-bonded via the peripheral sealing material 13, and the inside of the cell reflects the external light incident from the display observation surface side and transmits the light from the backlight BL. The reflection means 14 is provided.

The light semi-transmissive / reflecting means 14 is a second transparent substrate 12
Although disposed on the side, in this example, the 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 reflection means 14 is provided thereon. For the light semi-transmissive / reflecting means 14, for example, a metal thin film (half mirror) such as aluminum or a perfect reflection film (slit mirror or perforated mirror) having a large number of apertures as a light transmitting portion is used.

A color filter 16 is formed on the light semi-transmissive / reflecting means 14, and an electric insulating film (planarizing film) 1 is formed thereon.
A liquid crystal drive electrode 18 is provided via the electrode 7. An alignment film 19 is formed on the liquid crystal drive electrode 18. In addition,
The color filter 16 may be provided on the first transparent substrate 11 side.

On the side of the first transparent substrate 11, a liquid crystal drive electrode 21 as an opposite electrode of the liquid crystal drive electrode 18 is provided, and an alignment film 23 is formed on the liquid crystal drive electrode 21 with an electric insulating film 22 interposed therebetween. . Although not shown, the alignment films 19 and 23
A predetermined liquid crystal substance is enclosed between them. In addition, the phase difference plate 2 is provided on each outer surface of the first and second transparent substrates 11 and 12.
4 and the polarizing plate 25 are attached respectively.

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 used as a common electrode (scan electrode), and the liquid crystal drive electrode 21 on the first transparent substrate 11 side is used as a segment electrode (signal electrode).

In this example, the terminal portion 11a is provided on the first transparent substrate 11 side, and the common electrode 18 is predetermined from the terminal portion 11a via the transfer material contained in the peripheral sealing material 13. This driving voltage is supplied to the common electrode 18.

[0009]

However, in the prior art, since the common electrode 18 and the metal film forming the light semi-transmissive / reflecting means 14 are both formed on the same substrate (second transparent substrate 12) side, The following problems occur.

Usually, the common electrode 18 has about 10 to 20
The drive voltage of V is applied alternately in a line-sequential manner. On the other hand, the applied voltage to the segment electrode 21 is about 3
The voltage is ˜5 V, and the drive voltage is applied to the selected segment electrodes all at once.

Referring to FIG. 7, of the three illustrated common electrodes 18a to 18c, for example, the central common electrode 18b is the selection electrode, and the common electrode 18 adjacent to the selection electrode.
Assuming that a and c are non-selective electrodes, the metal film of the light semi-transmissive reflection means 14 exists on the back side of the common electrode 18 via the electric insulating film (dielectric) 17, and therefore the common electrode 18b
Capacitive coupling (coupling) occurs between the common electrode 18a and the common electrode 18c via the metal film.

Therefore, the common electrode 18 which is the selection electrode
The load capacity for a increases, and the power consumption increases accordingly. For example, assuming that the voltage required to drive the liquid crystal between the counter electrode and the counter electrode is usually 10 V, and the load capacitance becomes large due to the capacitive coupling, a drive voltage higher than that must be applied. This phenomenon is particularly remarkable when an aluminum thin film (half mirror) without an aperture is used as the light semi-transmissive reflective film, and the maximum is about 40.
% Power consumption increase.

If, for example, a slit mirror in which an opening (light transmitting portion) is provided in a complete reflection film is used as the light semi-transmissive / reflecting means 14, the capacitive coupling becomes weaker than in the case of the half mirror, but especially the power source. It cannot be said that it is sufficient to reduce the power consumption in a mobile phone or the like that requires the battery as a battery. In addition, the slit mirror has another problem that it is difficult to achieve both a high level of transmitted brightness and a good level of transmitted color.

The present invention has been made to solve the above problems, and a first object thereof is to reduce the power consumption of liquid crystal driving power. A second object of the present invention is to achieve both high transmission brightness and high transmission color reproducibility and high contrast.

[0015]

In order to achieve the above first object, the present invention provides a first transparent substrate on the display observation surface side and a second transparent substrate on the opposite display observation surface side with a peripheral sealing material interposed therebetween. A liquid crystal cell pressure-bonded by pressing, and a backlight arranged on the side opposite to the display observation surface of the liquid crystal cell, and a striped common electrode is formed on one of the transparent substrates.
Stripe-shaped segment electrodes orthogonal to the common electrode are formed on the other side of the second electrode.
The light from the above backlight is transmitted to the inner surface of the transparent substrate,
A semi-transmissive color liquid crystal display device having a light-semi-transmissive reflecting means made of a metal film for reflecting external light incident from the first transparent substrate side, and a color filter formed on the light-semi-transmissive reflecting means. In the above, the segment electrode is arranged on the side of the second transparent substrate provided with the light semi-transmissive / reflecting means, and the common electrode is arranged on the side of the first transparent substrate.

Even if the segment electrode and the metal film of the light semi-transmissive / reflecting means are formed on the same substrate side instead of the common electrode,
Capacitance coupling occurs between the adjacent segment electrodes through the metal film, but since the applied voltage to the segment electrodes is about 1/3 to 1/4 that of the common electrode, it is lower than that of the conventional example. It is possible to achieve power consumption.

In the case of segment electrodes, a signal voltage may be applied to adjacent segment electrodes at the same time. In that case, capacitive coupling does not occur between the adjacent segment electrodes, so that the voltage is further reduced. Power consumption can be expected.

The present invention is effective even if the above-mentioned light semi-transmissive reflecting means is a half mirror made of a metal thin film such as aluminum, but in order to make the capacitance coupling between the segment electrodes smaller, The light semi-transmissive reflection means has a light transmission part consisting of an opening for transmitting light from the backlight and a light reflection part consisting of a complete reflection film, and the light transmission part and the light reflection part are segment electrodes. It is preferable that the slit mirrors are formed in stripes in parallel.

In the present invention, the light transmitting portion and the light reflecting portion are assigned to each sub-pixel of the color filter, and black is provided between the sub-pixels so as to correspond to the space between the segment electrodes. By disposing a mask (light-shielding film), it is possible to prevent light leakage between the segment electrodes.

When the aperture ratio of the light transmissive portion is set to, for example, 50% or more, placing importance on the appearance of the transmitted light, it is preferable to dispose the black mask on the light reflective portion. This makes it possible to maintain the designed aperture ratio without affecting the aperture ratio of the light-transmitting portion even if the position shift or the line width enlargement occurs when the black mask is formed. It will be possible.

In order to achieve the above-mentioned second object (combination of transmitted luminance and transmitted color reproducibility and high contrast), in the present invention, the light reflecting portion is made of a silver-based complete reflection film, and the light transmitting portion is also provided. The aperture ratio of the part is 30% or more. Also,
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 R, G, B
The color filter is plotted on the CIE chromaticity coordinates, and the area value of the region surrounded by three points is multiplied by 10,000.

[0022]

FIG. 1 is a schematic sectional view showing a first embodiment of the present invention. In the liquid crystal cell 10A included in the semi-transmissive color liquid crystal display element of the present invention, light semi-transmissive reflection is used. The segment electrode 21 (see FIG. 2B) is provided on the second transparent substrate 12 side on which the means 14 is formed, and the common electrode 18 (see FIG. 2A) is provided on the first transparent substrate 11 side.
Is provided.

Therefore, the segment electrode 21 is connected to the predetermined lead electrode of the terminal portion 11a through the transfer material contained in the peripheral sealing material 13, but the other construction is the same as in the previous figure. It may be the same as the conventional example described in 6. Instead of using the transfer material, the common electrode 18 and the segment electrode 21 may be directly drawn to the terminal portions of the respective substrates, that is, so-called bidirectional drawing.

By arranging the segment electrode 21 on the second transparent substrate 12 side as in the first embodiment, it is possible to significantly reduce the power consumption as compared with the conventional example. That is, the applied voltage to the segment electrode 21 is usually about 3 to 5 V, which is about 1/3 to 1/4 of the applied voltage (about 10 to 20 V) to the common electrode, as described above.

Therefore, even if capacitance coupling occurs between the adjacent segment electrodes through the metal film of the light semi-transmissive reflecting means 14 and the load capacitance increases, the applied voltage is low and the capacitance coupling force is weak in the first place. Therefore, it is possible to set a slightly higher voltage in anticipation of an increase in load capacitance than the normal applied voltage.

Further, in the full dot matrix display, the probability that a signal voltage is simultaneously applied to the adjacent segment electrodes on the segment electrode 21 side is relatively high. In that case, the capacitance between the adjacent segment electrodes is large. Since no coupling occurs, further reduction in power consumption can be expected.

The metal film forming the light semi-transmissive / reflecting means 14 may be any one of a half mirror, a perforated mirror and a slit mirror, but in order to further reduce the power consumption, the electrostatic film is used. A slit mirror whose capacitive coupling force is weakened is preferable. FIG. 2C schematically shows an example of the slit mirror.

The slit mirror 140 is formed by forming a plurality of light transmitting portions 141, which are slit-shaped openings of a predetermined width and which transmit light from the backlight BL, on a metal film in parallel with each other at regular intervals. The metal film portion left between the light transmitting portions 141 functions as the light reflecting portion 142. The material is preferably a silver-based complete reflection film having good reflection efficiency.

On the second transparent substrate 12, the light diffusion layer 15, the slit mirror 140, the color filter 16, the electric insulating film (planarizing film) 17, the segment electrodes 21, and the alignment film 1 are formed.
9 are sequentially formed, but the light transmission part 141 and the light reflection part 1 of the slit mirror 140 are formed with respect to the segment electrode 21.
42 are arranged in parallel.

Here, the slit mirror 140, the color filter 16 and the segment electrode 21 will be described with reference to FIG. 3B which is an enlarged plan view of the main part of FIG. 3A and its sectional view.
The positional relationship and the arrangement of the black mask (light-shielding film) 30 will be described.

One pixel of the color liquid crystal display element
Is a set of R, G, B, and each unit of R, G, B is a sub-pixel (sub-pixel) SP, and each sub-pixel SP has a width substantially equal to one line width W of the segment electrode 21. It is arranged at a position corresponding to the segment electrode 21.

With respect to the slit mirror 140, a light transmitting portion 141 and a light reflecting portion 142 are assigned to each sub-pixel SP. The widths of the light transmitting portion 141 and the light reflecting portion 142 with respect to the sub-pixel SP are relatively determined. For example,
If the area of the sub-pixel SP is 100 and the opening width of the light transmission part 141 is 30%, the width of the light reflection part 142 is the remaining 70%.

In order to prevent light leakage (light leakage) between the segment electrodes 21, a black mask 30 is arranged between the sub-pixels SP. That is, the black mask 30
Are provided at positions corresponding to between the segment electrodes 21a and 21b adjacent to each other between the sub-pixels SP.

By the way, adjacent segment electrodes 21a
In order to prevent the capacitive coupling between the segment electrode 21b and the segment electrode 21b via the light reflecting portion (completely reflecting film) 142, the light reflecting portion 142 is provided adjacent to the segment electrode as in the example of FIG. It is preferable that they do not overlap. In this case, the black mask 30 has the light transmitting portion 141.
It is arranged so as to fill a part of.

However, in the case of designing the opening width of the light transmitting portion 141 to be, for example, 0.5 times or more of the segment electrode width W, with an emphasis on the appearance of the transmitted light, as shown in FIG. As shown in the enlarged plan view of the main part 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 a black mask is provided on the light reflecting portion 142. It is preferable to provide 30.

The reason is that when the black mask 30 is formed, the black mask may be displaced and the line width of the black mask may be increased. Then, in the example of FIG. 3, the aperture ratio of the light transmitting portion 141 is designed. This is because it will be different from the value. In this regard, according to the example of FIG. 4, even when the black mask is displaced or the black mask line width is expanded during the formation of the black mask, the aperture ratio of the light transmitting portion 141 is changed from the designed value. That's not it.

In this way, the black mask 30 is provided for each sub-pixel SP.
Are formed not only between the segment electrodes 21 but also at positions corresponding to the common electrodes 18.

This will be explained with reference to FIG. 5. R, G, B
Of the sub-pixels SP (R), SP (G), SP (B) so as to surround the sub-pixels
(S) and the black mask 30 (C) for the space between the common electrodes are formed in a grid pattern. Incidentally, if the electrode width of the common electrode 18 is 240 μm, the segment electrode 21
The electrode width is set to 80 μm, which is 1/3 of the width.

Next, as a second embodiment of the present invention, when a slit mirror 140 is used for the semi-transmissive reflection means 14, it is suitable for achieving both the transmission luminance and the transmission color reproducibility and a high contrast. The conditions will be described.

As the slit mirror 140, a silver-based (preferably Ag-Pd-based) perfect reflection film having high reflection efficiency is used. The opening area of the light transmitting portion 141 is preferably 30% or more (particularly 50 to 80%). Slit mirror 1
40 is parallel to the segment electrode 21.

Each sub-pixel SP (R), SP (G), SP
In (B), the color filters are 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 transmission part 141, and 0404 (film thickness 1.0 μm) manufactured by Mitsubishi Chemical Co., Ltd. is applied to the light reflection part 142.
Apply.

The color filter of the light transmitting portion 141 has a Y value of <50 in a transparent white display and a color area of> 40 (preferably Y value of <45 and color area> 50). In addition, the color filter of the light reflecting portion 142 has a Y value of> 55 in transmission white display and a color area of <15 (preferably, Y value).
The value is> 60 and the color area is <10).

The electrode width of the common electrode 18 is 240 μm,
Assuming that 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 is 20 μm.

[0044]

As described above, according to the present invention,
The liquid crystal cell is provided with a light semi-transmissive reflection means made of a metal film that transmits light from the backlight and reflects external light incident from the display observation surface side, and a color filter is provided on the light semi-transmissive reflection means. In the formed semi-transmissive color liquid crystal display element of full dot matrix display, the segment electrode is arranged on one transparent substrate side provided with the light semi-transmissive reflection means, and the common electrode is arranged on the other transparent substrate side. As a result, the liquid crystal driving power consumption can be reduced.

When a slit mirror is used for the light semi-transmissive reflection means, the light reflection portion is a silver-based complete reflection film, and the aperture ratio of the light transmission portion is 30% or more.
By setting the color filter of the light transmitting portion to have a color area of 40 or more and the color filter of the light reflecting portion to have a color area of 15 or less, it is possible to achieve both the transmission luminance and the transmission color reproducibility and to achieve high contrast. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing the internal structure of a transflective color liquid crystal display element 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 by the present invention.

3A and 3B are an enlarged plan view and a sectional view of an essential part 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 and a cross-sectional view thereof for explaining another arrangement of the black mask.

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 cross-sectional view showing the 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 (transparent substrate on display viewing side) 12 2nd transparent substrate (transparent substrate on non-display viewing side) 13 Peripheral sealing material 14 Light semi-transmissive reflection means 140 slit mirror 141 Light transmission part 142 Light reflector 15 Light diffusion layer 16 color filters 17,22 Electric insulation film 18 common electrode 19,23 Alignment film 21 segment electrodes 30 black mask BL backlight SP sub pixel

Claims (5)

[Claims] 1. 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 opposite display observation surface side with a peripheral sealing material, and the opposite display observation surface side of the liquid crystal cell. A backlight arranged in, a striped common electrode is formed on any one of the transparent substrates, and a striped segment electrode orthogonal to the common electrode is formed on the other one, and The second semitransparent substrate is provided with an inner surface of the second transparent substrate, which transmits light from the backlight and reflects external light incident from the first transparent substrate side. In a semi-transmissive color liquid crystal display device in which a color filter is formed on a reflecting means, the segment electrode is arranged on the second transparent substrate side including the light semi-transmissive reflecting means, and the first transparent substrate side. Semi-transmissive color liquid crystal display device, characterized in that the common electrode is disposed. 2. The light semi-transmissive / reflecting means has a light transmissive portion formed of an opening for transmitting light from the backlight and a light reflective portion formed of a perfect reflection film, and the light transmissive portion and the light reflective portion. The transflective color liquid crystal display element according to claim 1, wherein the portion is formed in a stripe shape in parallel with the segment electrode. 3. The light transmissive portion and the light reflective portion are assigned to each sub-pixel of the color filter, and a black mask is located between the sub-pixels and corresponds in position to the segment electrodes. 3. The transflective color liquid crystal display element according to claim 2, wherein the transflective color liquid crystal display element is arranged as described above. 4. The transflective color liquid crystal display element according to claim 3, wherein the black mask is disposed on the light reflecting portion. 5. The light reflection part is made of a silver-based complete reflection film, and the aperture ratio of the light transmission part is 30% or more.
5. A transflective color liquid crystal display device according to any one of items 1 to 4.