JP2002072229A - Liquid crystal display apparatus and electronic equipment using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semitransmission reflection type liquid crystal display apparatus with which so called area gradation display can be conducted, where the precision of gradation in transmitting type display is not damaged even when an error is generated in the dimension of opening parts of a reflection film. SOLUTION: In the liquid crystal display apparatus in which a liquid crystal is interposed between a pair of substrates and which has plural pixels, the pixels are constituted of plural sub dots, each area of which has a prescribed area ratio and reflection films corresponding to respective sub dots are provided on one of the pair of substrates. Then, opening parts having nearly the same shape with respect to the sub dots which constitute one pixel and the number corresponding to the prescribed area ratio are provided in the reflection films corresponding to the respective sub dots which constitute one pixel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display and an electronic apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a reflection type display in which external light such as natural light or indoor illumination light enters from an observation side and reflects the light to perform display, and light from a light source is transmitted from a side opposite to the observation side. 2. Description of the Related Art There is known a transflective liquid crystal display device capable of switching as necessary between a transmissive display and a display in which light is incident. Further, as a liquid crystal display device of this type, each of a plurality of pixels is constituted by a plurality of subdots (areas where a reflective electrode and a counter electrode face each other) having a predetermined area ratio, and a so-called area gradation display is performed. A liquid crystal display device that can be used has also been proposed.

FIG. 11 shows a pair of substrates constituting a transflective liquid crystal display device capable of displaying the area gradation as viewed from the inside (liquid crystal side) of the substrate located on the side opposite to the observation side. The configuration in the case is illustrated. As shown in the figure, a plurality of scanning lines 221 extending in a predetermined direction are provided on the substrate.
A plurality of data lines 222 extending so as to intersect with the scanning line 221 and a TFT (Thin Fil) serving as a switching element
m Transistor) 223 and a plurality of reflective electrodes 224 (224) connected to the scanning lines 221 and the data lines 222.
1, 2242 and 2243). Each of the reflective electrodes 224 is formed of a conductive material having reflectivity, and has a function of applying a voltage to liquid crystal sandwiched between the reflective electrode 224 and a counter electrode provided on the entire surface of the other substrate. It also has the function of reflecting incident light from the side. Here, each of the three reflective electrodes 2241, 2242, and 2243 arranged in the Y-axis direction in the figure corresponds to three sub-dots constituting one pixel (indicated by a broken line in FIG. 11). As shown in FIG. 11, the respective area ratios are 1: 2: 4. Then, by selectively turning on or off these three sub-dots constituting one pixel, an area gray scale display is realized. For example, three reflective electrodes 22 corresponding to one pixel
By applying a predetermined voltage only between the reflective electrode 2241 and the counter electrode among 41 to 2243 (that is, turning on the sub-dot), the gradation corresponding to the weight “1” for the pixel Display, and the reflective electrode 2
By applying a predetermined voltage only between the counter electrodes 241 and 2243 and the counter electrode, the weight “5” is set for the pixel.
And so on.

[0004] Each of the plurality of reflective electrodes 224 has an opening 224a for transmitting light incident from the rear side to perform transmissive display. Here, in order to perform the same area gradation display with high precision in the transmissive display, the area ratio of each of the openings 224a needs to be the same as the area ratio of each of the reflective electrodes 224. That is, the area ratio of the openings 224a provided in the reflective electrodes 2241, 2242, and 2243 needs to be 1: 2: 4.

[0005]

The opening 224a of each reflective electrode 224 is formed by forming a thin film of a conductive material having reflectivity on the surface of a base layer such as a resin layer. It is generally formed by performing patterning by wet etching. However,
In wet etching, since the etching rate is affected by various factors such as the temperature of the etchant and the impurity concentration, it is difficult to form the opening 224a with the desired dimensions with high accuracy. If the size of the opening 224a obtained by such a process is different from the expected size, there arises a problem that high-precision gray scale display cannot be performed in transmission type display. The details are as follows.

FIGS. 12 (a) to 12 (c) exemplify dimensions of an opening 224a to be provided in each of the above-mentioned reflective electrodes 224. FIG. Here, as shown by a solid line in FIG. 12A, assuming that the intended size (that is, the design size) of the opening 224a to be provided in the reflective electrode 2241 having the smallest area is horizontal a × vertical b. The expected size of the opening 224a to be provided in the reflective electrode 2242 is horizontal a × length 2b as shown in FIG. 12B, and the expected size of the opening 224a to be provided in the reflective electrode 2243 is as shown in FIG. (C)
As shown in FIG. Now, assuming that the openings 224a are formed according to the expected dimensions, each of the openings 224 of the three reflective electrodes 224 corresponding to one pixel.
The area ratio of a is ab: 2ab: 4ab, that is, 3
As in the case of the area ratio of the two reflective electrodes 224, the ratio is 1: 2: 4, and high-precision gradation display can be performed in the transmissive display.

However, as described above, since the accuracy of wet etching is limited, in practice, the region removed by etching (that is, the opening 224) is removed.
In some cases, the area of a) may be different from the expected area. For example, as shown by the broken lines in FIGS. 12A to 12C, the opening 224a of each reflective electrode 224 may be removed to a region longer by ε than the intended dimension.

Here, when the area of the opening 224a of each reflecting electrode 224 is examined in consideration of the etching error, the opening 22a of the reflecting electrode 2241 shown in FIG.
The area of 4a is (a + 2ε) (b + 2ε), and FIG.
The area of the opening 224a of the reflective electrode 2242 shown in (b) is (a + 2ε) (2b + 2ε), and the area of the opening 224a of the reflective electrode 2243 shown in FIG.
+ 2ε) (2b + 2ε). As can be seen from this, when a dimensional error occurs due to the etching, the area ratio of the opening 224a of each reflective electrode 224 does not become 1: 2: 4. As a result, in a transmissive display in which light is transmitted through the opening 224a to perform display, the amount of light transmitted through the opening 224a of each reflective electrode 224 does not become 1: 2: 4, so that high-precision gradation is achieved. There is a problem that display cannot be performed. In the above description, it is assumed that each of the openings 224a is wider than the expected area. However, the same problem occurs when each of the openings 224a is narrower than the expected area. Occurs.

The present invention has been made in view of the circumstances described above, and it is possible to perform high-precision gradation display in a transmissive display even when an error occurs in the dimension of an opening. It is an object to provide a liquid crystal display device and an electronic device using the same.

[0010]

In order to achieve the above object, the present invention provides a liquid crystal display device having a plurality of pixels in which a liquid crystal is sandwiched between a pair of opposing substrates. The area is composed of a plurality of sub-dots having a predetermined area ratio, and a reflection film corresponding to each of the sub-dots is provided on one of the pair of substrates, while each of the sub-dots constituting the pixel is provided. For the corresponding reflective film,
A characteristic feature is that openings of substantially the same shape in number corresponding to the predetermined area ratio are provided over the sub-dots constituting the pixel.

With this configuration, even when the opening is formed in a size different from the expected size,
The area ratio of the opening corresponding to each sub-dot can be the same as the area ratio of the sub-dot. As a result, there is an advantage that the transmissive display can be performed with high-accuracy gradation display even though the size of the opening is shifted.

In the present invention, an alignment film having been rubbed in a predetermined direction is formed on the one substrate, and the opening is formed in a long shape having a longitudinal direction substantially the same as the predetermined direction. It may be shaped like a letter. By doing so, the display quality in the reflective display and the display quality in the transmissive display can be made uniform.

In the present invention, a transparent electrode is formed on the liquid crystal side of the other substrate of the pair of substrates, and the reflection film is formed on the liquid crystal side of the one substrate. It may be an electrode facing the transparent electrode. That is, a reflective film for reflecting incident light may have a function as an electrode for applying a voltage to the liquid crystal. In such a case, it is not necessary to separately provide a reflection film for reflecting incident light and an electrode for applying a predetermined voltage to the liquid crystal on the one substrate, so that the manufacturing cost is reduced and the structure is reduced. Can be simplified.

On the other hand, of the pair of substrates, a first electrode is formed on the liquid crystal side of the one substrate, and a second electrode is formed on the liquid crystal side of the other substrate. Is also good. In such a case, the second electrode does not need to have reflectivity, and as a result, the first electrode and the second electrode sandwiching the liquid crystal can be formed of the same material.

Note that the liquid crystal display device according to the present invention can be used as a display unit of various electronic devices.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. Such an embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.

A: Configuration of Embodiment First, an embodiment in which the present invention is applied to an active matrix type transflective liquid crystal display device will be described. In the following, a TFT (Thin Film Transistor; a three-terminal switching element) is used as a switching element.
The case of using a thin film transistor) will be exemplified.

FIG. 1 is a cross-sectional view schematically illustrating the configuration of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 1, this liquid crystal display device has a TN between a first substrate 11 and a second substrate 12 which face each other with a seal member 14 interposed therebetween.
The liquid crystal panel 1 includes a liquid crystal 13 of a (Twisted Nematic) type or the like, and the backlight unit 2 disposed on the second substrate 12 side of the liquid crystal panel 1. In FIG. 1 and each of the drawings shown below, the scale of each layer and each member is made different so that each layer and each member have a size that can be recognized in the drawing.

The backlight unit 2 includes a linear fluorescent tube 21 for irradiating light, a reflecting plate 22 for reflecting light emitted from the fluorescent tube 21, and guiding light from the fluorescent tube 21 to the entire surface of the liquid crystal panel 1. A light guide plate 23 and a diffusion plate 2 for uniformly diffusing the light guided by the light guide plate 23 to the liquid crystal panel 1
4 and a reflector 25 for reflecting light emitted from the light guide plate 23 to the side opposite to the liquid crystal panel 1 toward the liquid crystal panel 1. Here, the fluorescent tube 21 is not always turned on, but is turned on in response to an instruction from a user or a detection signal from a sensor when used in an environment where there is almost no external light. .

The first substrate 11 and the second substrate 12 constituting the liquid crystal panel 1 are plate members having optical transparency, such as glass, quartz, and plastic. Note that, in practice, a polarizing plate or a retardation plate for polarizing incident light is adhered to the outer surfaces of the first substrate 11 and the second substrate 12 (the side opposite to the liquid crystal 13). Since it does not directly relate to the present invention, its description and illustration are omitted.

On the inner surface of the first substrate 11 (on the side of the liquid crystal 13), a counter electrode 111 is formed over the entire surface. The opposing electrode 111 is made of a transparent conductive material such as ITO (Indium Tin Oxide) so as to oppose a plurality of reflective electrodes (details will be described later) formed on the second substrate 12.
Formed by The surface of the first substrate 11 on which the counter electrode 111 is formed is covered with an alignment film 112.
This alignment film 112 is an organic thin film such as polyimide,
A rubbing process is performed to define the alignment direction of the liquid crystal 13 when no voltage is applied.

On the other hand, a plurality of reflective electrodes, switching elements, and the like are formed on the inner surface of the second substrate 12, and are covered with an alignment film 125 similar to the alignment film 112. Here, a configuration near each reflective electrode of the second substrate 12 will be described with reference to FIG.

As shown in FIG. 2, a plurality of scanning lines 121 extending in a predetermined direction (X direction in FIG.
And a plurality of data lines 122 extending in a direction intersecting the scanning lines 121 (Y direction in the drawing). A reflection electrode 124 is formed at a portion where the scanning line 121 and the data line 122 intersect with a TFT 123 interposed therebetween. Each reflective electrode 124 in the present embodiment is formed of a conductive material having reflectivity, for example, aluminum or silver, and has a function of reflecting incident light from the first substrate 11 side, and a function of reflecting the above-described counter electrode. It also has a function as an electrode for applying a voltage to the liquid crystal 13 sandwiched between the liquid crystal 11 and the liquid crystal 13. Specifically, the orientation of the liquid crystal 13 sandwiched between the first substrate 11 and the second substrate 12 changes when a voltage is applied between the counter electrode 111 and the reflective electrode 124. In the following, the region where the alignment state of the liquid crystal 13 changes in this manner (that is,
The area where the reflective electrode 124 and the counter electrode 111 face each other) is called a sub dot. In the present embodiment, Y
The area ratio of the three subdots arranged in the axial direction, that is, the area ratio of the reflective electrode 124 is 1: 2: 4. As shown by the broken line in FIG. 2, one pixel is formed by these three subdots. Is configured.

With such a configuration, each sub-dot is turned on or off according to the values of the most significant bit, the second most significant bit, and the least significant bit of the 3-bit gradation data given for one pixel. Area gradation display of eight gradations according to the gradation data is realized. In the following, as shown in FIG. 2, among the three reflective electrodes 124 forming one pixel, the one having the smallest area is referred to as “reflective electrode 1241”, and the one having the largest area is referred to as “reflective electrode 124”.
3 "and those having an intermediate area are referred to as" reflective electrode 1242 ". However, when it is not necessary to particularly distinguish each reflective electrode, it is simply referred to as “reflective electrode 124”.

Further, as shown in FIG.
Reference numeral 4 has an opening 124a for transmitting light from the backlight unit 2 to perform transmissive display. Hereinafter, an aspect of the opening 124a which is a characteristic part of the present invention will be described in detail.

First, for each of the three reflective electrodes 124 corresponding to one pixel, the area ratio of the respective reflective electrodes 124 (ie, the area ratio of the subdots forming one pixel)
Are provided in the number corresponding to the number of the openings 124a. For example, in FIG. 2, three reflective electrodes 1241 and 124
Since it is assumed that the area ratio between 2 and 1243 is 1: 2: 4, the opening 124 a is
, One for the reflective electrode 1242, two for the reflective electrode 124
3 has a configuration in which four pieces are provided. When a plurality of openings 124a are provided in one reflection electrode 124 (that is, in the case of the reflection electrodes 1242 and 1243 shown in FIG. 2), these openings 124a are formed apart from each other.

Further, the openings 124a formed in each of the three reflective electrodes 1241, 1242 and 1243 corresponding to one pixel have substantially the same shape over these reflective electrodes 124. In the present embodiment, the openings 124 provided in any of the reflective electrodes 124
a also has a rectangular shape having a long side having a length a in the X-axis direction and a short side having a length b in the Y-axis direction (see FIG. 4A).

FIG. 3 is a cross-sectional view illustrating a specific configuration near the TFT 123 and the reflective electrode 124 described above. As shown in the figure, a semiconductor layer 1231 made of polysilicon is provided on a glass substrate 12a constituting the second substrate 12 via a base layer 12b, and the surface thereof is covered with an insulating film 1233.

As described above, the TFT 123 is provided at the intersection of the scanning line 121 extending in the X direction and the data line 122 extending in the Y direction. Here, a portion of the semiconductor layer 1231 that overlaps with the scanning line 121 is a channel region 1231a. In other words, a portion of the scan line 121 that intersects with the semiconductor layer 1231 is used as the gate electrode 1232.

In the semiconductor layer 1231, the lightly doped source region 1 is located on the source side of the channel region 1231a.
231b and a high-concentration source region 1231s are provided, while a low-concentration drain region 1231c is provided on the drain side.
A so-called LDD (Lightly Doped Drain) structure is provided by providing a high concentration drain region 1231d.

Of these, the high concentration source region 1231s
Are connected to a data line 122 made of aluminum or the like via a contact hole CH1 for opening the insulating layer 1233 and the interlayer insulating film 1236. On the other hand, the high-concentration drain region 1231d is formed in the intermediate conductive film 12 having the same layer as the data line 122 by the contact hole CH2 for opening the insulating film 1233 and the interlayer insulating film 1236.
35. Then, the intermediate conductive film 123
5 is a contact hole 123 for opening the resin layer 12c.
7 is connected to the reflection electrode 124. That is, the reflective electrode 124 is formed via the intermediate conductive film 1235.
It is connected to the high concentration drain region 1231d of the semiconductor layer 1231.

Here, the resin film 12c is made of a photosensitive acrylic resin or the like, and its surface is a rough surface on which a large number of fine irregularities are formed. Since each reflective electrode 124 is formed in a thin film on the surface of the resin film 12c, irregularities reflecting the irregularities on the resin film 12c are formed on the surface of the reflective electrode 124. Therefore, the first substrate 1
The incident light from the first side is emitted from the first substrate side after being appropriately scattered by the unevenness of the surface of the reflective electrode 124, so that the background is reflected in an image visually recognized by an observer, or the light from indoor lighting. It is possible to avoid a situation in which light is reflected.

The reflection electrode 124 having the opening 124a is formed, for example, as follows. That is, a conductive material (for example, aluminum or silver) having reflectivity is provided over the entire surface of the resin film 12c in which the contact hole 1237 is provided and whose surface is roughened.
Is formed. Then, a region of the thin film surface where the reflective film is to be formed, that is, of the thin film surface,
A region where the opening 124a is to be formed and each reflective electrode 12
A photoresist is formed on the surface of the region excluding the gap region 4. Subsequently, by performing wet etching on this surface, a region of the thin film where the photoresist is not formed is removed, and then the photoresist is removed. Through this step, the reflective electrode 124 having the opening 124a can be formed.

As described above, in the present embodiment, one sub-dot having a predetermined area ratio is used as one sub-dot.
While one pixel is formed, a reflective electrode 124 is provided corresponding to each sub-dot. Each reflective electrode 124 has the same shape over these sub-dots, and the area ratio of each sub-dot (reflective electrode 124). And the number of openings 124a corresponding to the number of openings 124a. With such a configuration,
In the step of providing the opening 124a in the reflective electrode 124, even if the area of the opening 124a actually formed is different from the expected area of the opening 124a, a plurality of pixels corresponding to one pixel are formed. There is an advantage that the area ratio of the opening 124a provided in each of the reflective electrodes can be set to a desired area ratio. The details are as follows.

First, as shown in FIG. 4A, it is assumed that each reflective electrode 124 has a rectangular opening 124a having a long side length a and a short side length b. In this case, assuming that each opening 124a is formed to the expected size, the area of the opening 124a of the reflective electrode 1241 is ab
(= A × b × 1), opening 124 of reflective electrode 1242
The total area of a is 2ab (= a × b × 2), and the reflective electrode 12
The total area of the 43 opening portions 124a is 4ab (= a × b × 4
), The ratio of the total area of the openings 124a for each reflective electrode 124 corresponding to one pixel matches the area ratio “1: 2: 4” of these reflective electrodes 124 (subdots).

On the other hand, as shown in FIG. 4B, although the thin film of the reflective metal is etched to provide the opening 124a having the above-described size, the area is actually formed. It is assumed that the metal film is excessively removed by the length ε in all directions. In this case, each opening 124a has a horizontal (a + 2ε) and a vertical (b + 2ε) rectangular shape. Therefore, the opening 12 of the reflective electrode 1241
The total area of 4a is (a + 2ε) (b + 2ε), and the reflection electrode 1
242 has a total area of 2 (a + 2ε) (b
+ 2ε), and the total area of the opening 124a of the reflective electrode 1243 is 4 (a + 2ε) (b + 2ε). In other words, even if the opening 124a formed in each reflective electrode 124 has a size different from the expected size, the size of one
For each of the three sub-dots constituting the pixel, the ratio of the total area of the openings 124a corresponding to each sub-dot is 1:
2: 4, that is, the expected area ratio. As described above, in the related art, if the dimensions of the opening 124a differ due to manufacturing errors, the area ratio of the opening 124a does not become the expected area ratio with this. As a result, there is a problem that high-precision gradation display cannot be performed in the transmission type display. On the other hand, according to the present embodiment, as described above, even when the area of each opening 124a is different from the expected area, the ratio of the total area of the opening 124a for each sub-dot is obtained. Is the same as the area ratio of each sub-dot (reflective electrode 124). That is, according to the present embodiment, it is possible to realize a highly accurate transmissive display even when a manufacturing error occurs.

B: Modifications Although one embodiment of the present invention has been described above, the above embodiment is merely an example, and various modifications may be made to the above embodiment without departing from the spirit of the present invention. be able to. For example, the following modifications can be considered.

<Modification 1> In FIG. 2 exemplifying the configuration in the vicinity of the reflective electrode 124 according to the above-described embodiment, the opening 124a provided in each reflective electrode 124 is formed in parallel with the X-axis direction and the Y-axis direction. Although it was a rectangular shape consisting of sides,
The mode of disposing the opening 124a is not limited to this, and may be as follows, for example.

FIG. 5A is a plan view showing the configuration near the reflective electrode 124 in the liquid crystal display device according to this modification. In FIG. 5, as shown in FIG.
The rubbing process is performed on the alignment film 112 formed on the first substrate 11 in a direction forming an angle of 45 degrees with the positive direction of the Y-axis, while the second substrate 12 on which each reflective electrode 124 is formed.
It is assumed that the rubbing process is performed on the alignment film 125 in a direction perpendicular to this direction, that is, in a direction forming an angle of 45 degrees with the negative direction of the X axis. And FIG.
As shown in (a), each reflective electrode 124 according to the present modification example
Has an elongated shape with the rubbing direction with respect to the alignment film 125 as the longitudinal direction. With such a shape, the following effects can be obtained. The first effect is that the rubbing process becomes easy. FIG.
As shown in the figure, the surface of the opening 124a is lower by the thickness of the reflective electrode 124 than the peripheral reflective portion. Also in this modified example, the thickness is reduced by the thickness of the reflective electrode. Therefore, by adopting such a shape, it is easy for the bristle to enter during the rubbing process, and it is possible to prevent the rubbing process at the step portion of the opening from becoming insufficient, and to improve the display quality.
As a second effect, transmissive display can be performed without installing the transparent electrode 128 formed on the surface of the reflective electrode 124. Such an effect can be obtained by making the shape of the opening a long shape whose short side is sufficiently small as much as the thickness of the liquid crystal layer. In this modification, each of the reflection electrodes 1
24 has the same number of openings 124a as the area ratio, and these openings 124a have substantially the same shape as in the above embodiment. With the above configuration, there is an advantage that the difference between the display quality in the reflective display and the display quality in the transmissive display can be reduced. The details are as follows.

As shown in FIG. 6, the direction of the electric field generated by the reflective electrode 124 and the opposing electrode 111 is perpendicular to both substrates except for the opening 124a, and the intensity is also one. Looks like. On the other hand, since no electrode exists in the opening 124a, only an electric field is generated by leakage from the opening end of the reflective electrode 124. For this reason, the electric field intensity near the opening 124a becomes weaker as the distance from the edge of the opening 124a increases, and is not uniform. This means, conversely, a point equidistant from the opening end of the reflective electrode 124,
In other words, it means that the electric field strengths are almost equal at the points indicated by the broken lines in FIG.

On the other hand, when no voltage is applied, the long liquid crystal molecules are aligned so that the longitudinal direction thereof substantially coincides with the rubbing direction.

In consideration of these circumstances, the opening 124a
Consider the behavior of the liquid crystal molecules M located in the vicinity. First, as shown in FIG. 7B, an opening 124a whose longitudinal direction is different from the rubbing direction is formed in each reflective electrode 12.
4, and a case where a potential difference is generated between the reflective electrode 124 and the counter electrode 111 under such a configuration (particularly, a case where the potential difference is small) is assumed. In this case, as shown in the figure, the strength of the electric field acting on one end of the long liquid crystal molecule M is different from the strength of the electric field acting on the other end. Like the liquid crystal molecules M located in the contributing region, no tilt occurs. As a result, the directions of the optical rotations of the light passing through the opening 124a and the light reflected by the reflective electrode 124 are different from each other, so that a difference occurs between the display quality in the transmissive display and the display quality in the reflective display. .

On the other hand, as shown in FIG. 7A, each reflective electrode 124 is provided with an opening 124a whose longitudinal direction is substantially the same as the rubbing direction, as shown in FIG. Assume that a potential difference is generated between the reflection electrode 124 and the counter electrode 111 as the configuration shown in FIG. In this case, as shown in FIG.
Since the strength of the electric field acting on both ends of the long liquid crystal molecules M is the same, the liquid crystal molecules M located in the opening 124a are:
The tilting is performed in the same manner as the liquid crystal molecules M located in the region where the electrode exists (that is, the region contributing to the display in the reflective display). That is, since the directions of rotation of the light passing through the opening 124a and the light reflected by the reflective electrode 124 are substantially equal, the difference between the display quality in the transmissive display and the display quality in the reflective display can be reduced. is there.

In the case of the configuration shown in this modification,
It is desirable that the longitudinal direction of the opening 124a of each reflective electrode 124 coincides with the rubbing direction. However, even if they do not exactly coincide with each other, as long as they are within an angle range of ± 15 °, the above display quality is obtained. Can be suppressed to a level that does not hinder practical use.

<Modification 2> In the above embodiment, the reflection electrode 124 functions as a reflection film for reflecting the incident light from the first substrate 11 side, and serves to apply a predetermined voltage to the liquid crystal. Although the configuration has the function also as the electrode, the configuration may be such that the reflection film and the electrode are separately provided. Hereinafter, the configuration of the liquid crystal display device according to the present modification will be described with reference to FIG. In addition, among the units illustrated in FIG. 8, the same parts as those in FIG. 1 described above are denoted by the same reference numerals, and description thereof will be omitted.

In this modification, a reflection film 126 is formed on the inner surface of the second substrate 12. This reflection film 126
Has the same shape as the reflective electrode 124 shown in FIG. Specifically, each reflection film 126 is formed apart from each other corresponding to three sub-dots constituting one pixel, and their area ratio is 1: 2: 4. further,
In each of the three reflecting films 126 having such an area ratio, the number of openings 126 corresponding to the area ratio is formed, and the shape of each opening 124a is determined by the three reflecting films 126.
Over the same shape. However, in the above embodiment, the reflection electrode 124 is connected to the scanning line 121 and the data line 122 via the TFT 123. However, in this modification, each reflection film 126 is not used as an electrode. It is not connected to any of these elements because it is used only as a reflective film for reflecting incident light. For the same reason, the material for forming the reflective film 126 does not necessarily have to be conductive as long as the material has reflectivity.

The surface of the second substrate 12 on which the reflection film 126 is formed is covered with an insulating layer 127 having transparency. Then, on the surface of the insulating layer 127, a plurality of scanning lines and data lines, TFTs (both not shown) located at intersections thereof, and TFTs connected to the TFTs and sandwiched between the counter electrodes 111. A transparent electrode 128 for applying a predetermined voltage to the liquid crystal 13 is formed. The transparent electrode 128 is formed of a transparent conductive material such as ITO, and is patterned into a shape corresponding to the sub-dot constituting each pixel. Further, the surface of the insulating layer 127 on which the transparent electrode 128 is formed is covered with the alignment film 125 as in the above embodiment.

As described above, the reflection film 126 and the transparent electrode 12
8 can be provided separately, and the same effect as in the above embodiment can be obtained. Although FIG. 8 illustrates a configuration in which the reflective films 126 are formed separately for each sub-dot, a configuration in which a reflective film is formed on the entire surface of the second substrate 12 may be employed. In this case, an opening that satisfies the conditions described in the above embodiment is formed in a region of the reflection film corresponding to the subdot.

<Modification 3> In the above embodiment, the number of openings 124a corresponding to the respective reflective electrodes 124 is made to correspond to the area ratio itself of the three reflective electrodes (sub dots) constituting one pixel. One for the reflective electrode 1241, two for the reflective electrode 1242, and four for the reflective electrode 1243
24a are provided, but each reflective electrode 12a
The number of the openings 124a provided in 4 is not limited to this. For example, the reflective electrode 1241 may have two openings, the reflective electrode 1242 may have four openings, and the reflective electrode 1243 may have eight openings. In short, in correspondence with each of the plurality of subdots corresponding to one pixel, the number of openings corresponding to the area ratio of these subdots is formed,
It is only necessary that the shape of each opening is substantially the same over these subdots.

Further, in each of the above embodiments, the case where eight gradation display is performed by setting the area ratio of three sub dots corresponding to one pixel to 1: 2: 4 has been exemplified. Of course, the area ratio of each sub-dot and the number of gradations are not limited to these.

<Modification 4> In the above embodiment, 3
Although a liquid crystal display device using a TFT as a terminal type switching element has been illustrated, the present invention is not limited to such a liquid crystal display device. Specifically, TFD
The present invention can be applied to a liquid crystal display device using a two-terminal liquid crystal display device typified by (Thin Film Diode) or a passive matrix liquid crystal display device having no switching element.

<Modification 5> In the above embodiment, 1
Although the pixel is composed of three sub dots, the following configuration can be considered when performing color display. That is, as shown in FIG. 9, one pixel is represented by R (red), G
It is composed of three sub-pixels corresponding to the colors (green) and B (blue), and each of these sub-pixels is composed of three sub-dots having an area ratio of 1: 2: 4. That is, one sub-pixel in the present modified example corresponds to one pixel shown in the above embodiment. Specifically, each of the reflective electrodes corresponding to the three sub-dots constituting each sub-pixel has openings of a number corresponding to the area ratio of the three sub-dots, and the shape of each opening is Have substantially the same shape over these subdots. In such a case, the same effect as in the above embodiment can be obtained.

C: Electronic Equipment Next, some electronic equipment using the liquid crystal display device according to the above-described embodiment will be described. C-1: Mobile Computer First, an example in which the above-described liquid crystal display device is applied to a mobile personal computer will be described. FIG.
(A) is a perspective view showing a configuration of the personal computer. In the figure, a computer 300 includes a main body 302 provided with a keyboard 301 and a liquid crystal display device 303 according to the above embodiment used as a display. C-2: Mobile Phone Further, an example in which the liquid crystal display device according to the above-described embodiment is applied to a display unit of a mobile phone will be described. FIG.
FIG. 2B is a perspective view illustrating the configuration of the mobile phone. As shown in the figure, the mobile phone 310 includes a plurality of operation buttons 311, an earpiece 312, a mouthpiece 313, and the above-described liquid crystal display device 314 as a display unit.

In addition to the electronic equipment described with reference to FIG. 10, a liquid crystal television, a viewfinder type / monitor direct-view type video tape recorder, a car navigation device, a pager, an electronic notebook, a calculator, a word processor , A workstation, a videophone, a POS terminal, a digital still camera, and a device equipped with a touch panel. Needless to say, the liquid crystal display devices according to the above-described embodiments and the modifications can be applied to these various electronic devices.

[0055]

As described above, according to the present invention,
Even when the area of the opening of the reflective film corresponding to each sub-dot is different from the expected area, high-precision gradation display can be performed in the transmissive display.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a plan view illustrating a configuration near a reflective electrode of the liquid crystal display device.

FIG. 3 is a cross-sectional view illustrating a configuration of a reflective electrode and a switching element of the liquid crystal display device.

FIG. 4 is a diagram for explaining an effect of the present invention.

FIG. 5A is a plan view illustrating a configuration near a reflective electrode in a liquid crystal display device according to the present modification, and FIG.
FIG. 3 is a view showing a rubbing direction in the same liquid crystal display device.

FIG. 6 is a cross-sectional view schematically illustrating a state of an electric field near an opening in the liquid crystal display device.

FIG. 7A is a diagram schematically illustrating a state of liquid crystal molecules near an opening in the liquid crystal display device, and FIG.
FIG. 4 is a diagram schematically illustrating a state of liquid crystal molecules near an opening in a liquid crystal display device in which the longitudinal direction of the opening is different from the rubbing direction.

FIG. 8 is a cross-sectional view illustrating a configuration of a liquid crystal display device according to another modification of the present invention.

FIG. 9 is a plan view illustrating a pixel configuration of a liquid crystal display device according to another modification of the present invention.

10A is a perspective view illustrating the configuration of a personal computer as an example of an electronic device to which the liquid crystal display device according to the embodiment of the present invention is applied, and FIG. 10B is another example of the electronic device. FIG. 2 is a perspective view illustrating the configuration of a mobile phone.

FIG. 11 is a plan view illustrating a configuration near a reflective electrode of a conventional liquid crystal display device.

FIG. 12 is a diagram illustrating a problem in a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel 11 ... 1st substrate 111 ... Counter electrode 112 ... Alignment film 12 ... 2nd substrate 121 ... Scanning line 122 ... Data line 123 ... TFT 124 ... Reflecting electrode 124a ... Opening Part 125 ... Orientation film 126 ... Reflection film 127 ... Insulating layer 128 ... Transparent electrode 13 ... Liquid crystal 14 ... Seal material 2 ... Backlight unit 21 ... Fluorescent tube 22 ... Reflection plate 23 ... Conduction Light plate 24 ... Diffusion plate 25 ... Reflection plate

Claims (5)

[Claims] 1. A liquid crystal display device having a plurality of pixels, wherein a liquid crystal is sandwiched between a pair of substrates facing each other, wherein the pixels are formed of a plurality of sub-dots each having a predetermined area ratio. Wherein one of the pair of substrates has a reflective film corresponding to each of the sub-dots, and a reflective film corresponding to each of the sub-dots of the pixel is a sub-dot of the pixel. A plurality of openings having substantially the same shape corresponding to the predetermined area ratio. 2. The one substrate has an alignment film that has been subjected to a rubbing process in a predetermined direction, and the opening has a long shape whose longitudinal direction is substantially the same as the predetermined direction. The liquid crystal display device according to claim 1, wherein: 3. A transparent electrode is formed on the liquid crystal side of the other substrate of the pair of substrates, and the reflective film is formed on the liquid crystal side of the one substrate and faces the transparent electrode. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is an electrode. 4. The liquid crystal display of claim 1, wherein a first electrode is formed on the liquid crystal side of the one substrate, and a second electrode is formed on the liquid crystal side of the other substrate. Item 3. The liquid crystal display device according to item 1 or 2. 5. An electronic apparatus using the liquid crystal display device according to claim 1.