JP4882277B2 - Color filter for liquid crystal display - Google Patents

Description

  The present invention relates to a color filter for a liquid crystal display device, and in particular, even when there is a misalignment during the formation of the alignment control protrusion on the colorless transparent layer above the through-hole portion, the height of the alignment control protrusion is high. The present invention relates to a color filter for a liquid crystal display device that does not become high.

FIG. 4 is a plan view schematically showing an example of a color filter used in the liquid crystal display device. FIG. 5 is a cross-sectional view taken along the line XX ′ of the color filter shown in FIG.
As shown in FIGS. 4 and 5, the color filter (4) used in the liquid crystal display device has a black matrix (41), a colored pixel (42), and a transparent conductive film (43) on a glass substrate (40). Are formed sequentially.
4 and 5 schematically show a color filter, and 12 colored pixels (42) are represented. In an actual color filter, for example, several hundreds are displayed on a 17-inch diagonal screen. A large number of colored pixels of about μm are arranged.

As a method for manufacturing a color filter having the above structure used in many liquid crystal display devices, a black matrix is first formed on a glass substrate to form a black matrix substrate, and then the black matrix on the black matrix substrate is used. A method is widely used in which a colored pixel is formed by aligning with the pattern, and a transparent conductive film is aligned and formed.
The black matrix (41) is a matrix having light shielding properties, the colored pixels (42) have, for example, red, green, and blue filter functions, and the transparent conductive film (43) is transparent. Provided as a simple electrode.

The black matrix (41) is composed of a matrix portion (41A) between the colored pixels (42) and a frame portion (41B) surrounding the peripheral portion of the region (display portion) where the colored pixels (42) are formed. Yes.
The black matrix determines the position of the colored pixels of the color filter, makes the size uniform, and shields unwanted light when used in a display device, making the image of the display device uniform and uniform. In addition, it has a function of making an image with improved contrast.

For the production of this black matrix substrate, a metal or a metal compound such as chromium (Cr) or chromium oxide (CrO _x ) as a black matrix material is formed into a thin film on a glass substrate (40). An etching resist pattern is formed on the formed thin film using, for example, a positive photoresist, and then an exposed portion of the formed metal thin film is etched and an etching resist pattern is stripped, and Cr, CrO _A method has been adopted in which a black matrix (41) made of a metal thin film such as _X is formed.
Alternatively, the black matrix (41) is formed on the glass substrate (40) by photolithography using a black photosensitive resin for forming a black matrix.

In addition, the colored pixels (42) are formed by providing a coating film on the black matrix substrate using, for example, a negative photoresist in which a pigment or other pigment is dispersed, and exposing and developing the coating film. A method of forming colored pixels is used.
The transparent conductive film (43) is formed on the black matrix substrate on which the colored pixels are formed by, for example, forming a transparent conductive film by sputtering using ITO (Indium Tin Oxide). .

The color filter (4) shown in FIGS. 4 and 5 has a basic function as a color filter used in a liquid crystal display device. The liquid crystal display device incorporates such a color filter to realize full color display, and its application range is dramatically expanded, and many products using liquid crystal display devices such as liquid crystal color TVs and notebook PCs are created. It was done.
With the development and practical use of various liquid crystal display devices, the following various functions have been added to the color filters used in the liquid crystal display devices in addition to the above basic functions.

1) Spacer function In a conventional liquid crystal display device, transparent spherical particles (beads) of glass or synthetic resin called spacers are dispersed to form a gap between substrates.
Since these spacers are transparent particles, if a spacer is included with the liquid crystal in the pixel, light will leak through the spacer during black display, and the substrate in which the liquid crystal material is enclosed Due to the presence of the spacers between them, the alignment of the liquid crystal molecules in the vicinity of the spacers is disturbed, and light leakage occurs at this part, and the contrast is lowered and the display quality is adversely affected.

As a technique for solving such a problem, a method of forming a photo spacer (protrusion) having a spacer function at a position of a black matrix between pixels by using a photosensitive resin and by a photolithography method has been developed.
FIG. 7 is a partial cross-sectional view of such a color filter for a liquid crystal display device. As shown in FIG. 7, in the color filter (7) for a liquid crystal display device, a black matrix (41), a colored pixel (42), and a transparent conductive film (43) are sequentially formed on a glass substrate (40). A photospacer (44) as a protrusion having a spacer function is formed on the transparent conductive film (43) above the black matrix (41). In the liquid crystal display device using such a color filter (7) for the liquid crystal display device, the photo spacer (44) is formed at a position avoiding the inside of the pixel, and thus the contrast is improved.

2) Orientation division function In the conventional liquid crystal display device, in order to uniformly align the liquid crystal molecules, polyimide is applied in advance on the transparent conductive film provided on both substrates sandwiching the liquid crystal, and the surface A uniform rubbing process is performed.
However, in TN type liquid crystal used in many liquid crystal display devices, in principle, it is difficult to obtain a wide viewing angle. In a halftone display state, light leaks at an oblique viewing angle, and the contrast is lowered and displayed. Quality deteriorates. That is, there is a problem that the viewing angle with good contrast is narrow.

  As one technique for solving such a problem, the liquid crystal molecules in one pixel are controlled so that the alignment direction of the liquid crystal molecules is not a single direction but a plurality of directions, and uniform halftone display is performed in a plurality of directions. In other words, an alignment-divided vertical alignment type liquid crystal display (MVA, Multi-domain Vertical Alignment-LCD) having a wide viewing angle has been developed.

  FIG. 8A is an explanatory diagram schematically showing a cross section of such an MVA-LCD. As shown in FIG. 8A, the MVA-LCD (80) includes a TFT side substrate (20) provided with alignment control protrusions (22a) and (22b) via liquid crystal molecules (21), and an alignment The color filter (8) provided with the control projection (23) is arranged, but the alignment control projections (22a) and (22b) and the alignment control projection (23) are staggered within one pixel. In the position.

As shown by the white arrow in FIG. 8A, in the state at the time of voltage application, the liquid crystal molecules between the alignment control protrusion (22a) and the alignment control protrusion (23) are diagonally leftward in the figure. The liquid crystal molecules between the alignment control protrusion (23) and the alignment control protrusion (22b) are inclined obliquely to the right. That is, the alignment of the liquid crystal molecules is controlled by providing protrusions instead of the rubbing treatment.
In the example shown in FIG. 8A, one pixel is divided into two, and the tilt direction of the liquid crystal molecules is two in one pixel, and the liquid crystal display device has excellent viewing angle characteristics. 8B and 8C are an enlarged plan view and a cross-sectional view showing another pixel of another example of the color filter for MVA-LCD. This example is a color filter (9) in which an orientation control protrusion (93) having a circular planar shape is formed. The tilt direction of the liquid crystal molecules becomes multidirectional within one pixel.

3) Transmission / reflection combined function The transflective liquid crystal display device having both the transmissive type and the reflective type in the above liquid crystal display device can be used in a bright outdoor environment or a dark indoor environment. FIG. 6 is a cross-sectional view of an example of a color filter used in a transflective liquid crystal display device. As shown in FIG. 6, this color filter is obtained by forming a black matrix (41), colored pixels (42), and a transparent conductive film (43) on a glass substrate (40).
The colored pixel (42) includes a colored pixel (42Tr) for transmissive display and a colored pixel (42Re) for reflective display. The colored pixel (42Re) for reflective display is composed of a colored portion (45) and a through hole portion (46).

  The colored portion (45Tr) of the transmissive display colored pixel (42Tr) and the reflective display colored pixel (42Re) has spectral characteristics suitable for transmissive display. By providing the through-hole part (46) in the colored pixel (42Re) for reflective display, the colored light of the colored part (45) and the white light of the through-hole part (46) are mixed, and the colored pixel (42Re) of the reflective display is mixed. The spectral characteristic is adjusted to an appropriate spectral characteristic for reflection display. The through hole portion (46) is filled with a colorless transparent resin.

The spacer function, the orientation dividing function, and the combined transmission / reflection function are added to the color filter (4) shown in FIG. 4, but one of the above functions is based on the use and specification of the color filter. Multiple functions are added.
These functions are provided by forming corresponding photo spacers, alignment control protrusions, and reflective display through-hole portions as layers associated with the basic color filter.

FIG. 9A is a plan view of an example of a color filter in which a basic color filter is provided with a through hole portion for reflection display, an alignment control protrusion, and a photo spacer. FIG. 9B is a cross-sectional view taken along the line AA ′ in FIG.
As shown in FIGS. 9 (a) and 9 (b), this color filter, which is shown as an example, includes a black matrix (41), a colored pixel (42), a colorless transparent layer (47), and a transparent on a glass substrate (40). A conductive film (43) and an alignment control protrusion (Mv) are formed.

The colored pixel (42) includes a colored pixel (42Tr) for transmissive display and a colored pixel (42Re) for reflective display. The colored pixel (42Re) for reflective display is composed of a colored portion (45) and a through hole portion (46).
The colored pixel (42Tr) for transmissive display and the colored portion (45) of the colored pixel (42Re) for reflective display are continuous and are formed simultaneously by photolithography.

A colorless transparent layer (47) is provided on the colored pixel (42Re) for reflective display, and the colorless transparent resin used for forming the colorless transparent layer (47) is filled in the through-hole portion (46). Yes. In this example, the colorless and transparent layer (47) is provided in a stripe shape having a width (c) in the Y-axis direction on the colored pixel (42Re) for reflective display. Not limited to this example, the colorless and transparent layer (47) may be provided in a solid form like the overcoat layer.
A transparent conductive film (43) is formed on the entire surface of the glass substrate (40) on which the black matrix (41), the colored pixels (42), and the colorless transparent layer (47) are formed.
On the transparent conductive film (43), alignment control projections (Mv) are formed.

  The alignment control protrusion (Mv) has a circular planar shape, and is disposed on the colorless transparent layer (47) above the through-hole portion (46) of the colored pixel (42Re) for reflective display via the transparent conductive film (43). One is provided. The diameter (φ1) of the alignment control protrusion (Mv) is, for example, about 16 μm.

FIGS. 10A and 10B show a state in which the alignment control protrusion (Mv) is formed in a position shifted in the X direction with respect to the colored portion (45) of the colored pixel (42Re) in the reflective display. Is.
As shown in FIG. 10, an alignment control protrusion (Mv) having a diameter (φ1, φ1 <W1) is provided above a through hole portion (46) having a width (W1). The peripheral part of (Mv) has a width (D1) overlapping the end part (45E) of the colored part (45) on the colorless transparent layer (47) [D1 = (W1-φ1) 1/2].
Specifically, an alignment control protrusion (Mv) having a diameter (φ1) of 16 μm is provided above a through hole portion (46) having a width (W1) of 20 μm, and a width is provided above an end portion (45E) of the colored portion. (D1) There is an overlap of 4 μm.

  In FIG. 11, when a colorless transparent resin is applied to form a colorless transparent layer (47), the through hole portion (46) is filled with the colorless transparent resin, but the colorless transparent layer above the through hole portion (46). The surface of (47) is not flat and a dent (48) is produced. When the alignment control protrusion (Mv) having the height (T2) is formed on the colorless transparent layer (47) having the depression (48) having the depth (T1), the alignment control from the surface of the colorless transparent layer (47) is performed. The height (T3) of the projection (Mv) is a height that is lower by the depth (T1) of the recess (48) (T3 = T2-T1).

Specifically, the depth (T1) of the depression (48) is obtained when the colorless transparent layer (47) having a thickness of about 2.0 μm is formed on the colored portion (45) having a thickness of about 1.4 μm. It becomes about 0.2 μm. In FIG. 11, T2 is about 1.6 μm, and T3 is about 1.4 μm.
Therefore, in order to obtain the desired height (T3) of the alignment control projection (Mv), the height (T1) of the recess (48) is expected.

  As shown in FIG. 10, an alignment control projection (Mv) having a diameter (φ1) of 16 μm is provided above a through hole portion (46) having a width (W1) of 20 μm with a positional deviation (D) of 8 μm at the time of formation. As a result, an overlap with a width (D2) of 6 μm occurs above the end (45E) of the colored portion. As a result, the height of the alignment control projection (Mv) from the surface of the colorless transparent layer (47) is the same as the height (T3) of the first alignment control projection (Mv) without misalignment shown in FIG. On the other hand, the height indicated by the reference sign (ΔT) is approximately 0.1 μm higher.

The height (T2) of the alignment control protrusion (Mv) shown in FIG. 11 is about 1.6 μm, but has a variation of about 0.2 μm. A variation in height (ΔT = 0.2 μm) due to positional deviation is added to the variation 0.2 μm of the alignment control projection (Mv) itself, and the variation in the height of the alignment control projection (Mv) is large. It will be a thing.
If the variation in the height of the alignment control protrusion (Mv) becomes large, the alignment unevenness occurs in the liquid crystal and affects the display quality. Therefore, the variation in the height due to the displacement is not preferable.

FIG. 12 is an enlarged cross-sectional view of the portion shown in FIG. FIG. 12 illustrates the relationship between the orientation control protrusion (Mv) and the height of the photospacer (Ps). FIG.
), The photospacer (Ps) is located in the Y-axis direction of the alignment control protrusion (Mv), and therefore, for the sake of explanation, it is assumed that the photospacer (Ps) has been moved to the position indicated by the dotted line in FIG.
As shown in FIG. 12, the first orientation control protrusion (Mv1) having a height (T2) of 1.6 μm on the colorless transparent layer (47) having a depth (T1) of the depression (48) of 0.2 μm. The height (T3) of the first alignment control protrusion (Mv1) from the colorless transparent layer (47) is 1.4 μm.

The height (T5) of the photospacer (Ps) is, for example, 1.8 μm, and the height (T6) from the colorless transparent layer (47) is 1.6 μm (T6 = T5-T1). Accordingly, the difference in height between the height (T6) of the photospacer (Ps) from the colorless transparent layer (47) and the height (T3) of the alignment control projection (Mv) from the colorless transparent layer (47). (T7) is 0.2 μm.
In contrast to the fact that there is almost no difference in height (T7), the variation in height (T) due to misalignment is added to the variation in the height (T2) of the alignment control projection (Mv), and the opposite When the distance from the substrate is narrowed and the total variation is, for example, 0.2 μm or more, alignment irregularity occurs in the liquid crystal, which deteriorates display quality.
JP 2004-302291 A

  The present invention has been made in order to solve the above-mentioned problem. The planar shape is oriented circularly on the colorless transparent layer having a depression above the through-hole portion in the color filter for a transflective liquid crystal display device. In the color filter provided with the control protrusion, when forming the alignment control protrusion, the alignment control from the colorless transparent layer is performed even if the alignment control protrusion is misaligned with the colored portion of the colored pixel of the reflective display. It is an object of the present invention to provide a color filter for a liquid crystal display device in which the height of the projection is not increased.

  The present invention provides, on a glass substrate, at least a colored pixel for transmissive display, a colored pixel for reflective display, a colorless transparent layer on the colored pixel for reflective display, and a colorless upper portion of a through-hole portion constituting the colored pixel for reflective display. In the color filter for a liquid crystal display device in which the orientation control projection having a circular planar shape is formed on the transparent layer, the overlapping width of the orientation control projection to the colored portion located below the orientation control projection is A color filter for a liquid crystal display device having a diameter of ¼ or less of the diameter of the alignment control protrusion.

  The present invention provides, on a glass substrate, at least a colored pixel for transmissive display, a colored pixel for reflective display, a colorless transparent layer on the colored pixel for reflective display, and a colorless upper portion of a through-hole portion constituting the colored pixel for reflective display. In the color filter for a liquid crystal display device in which the orientation control projection having a circular planar shape is formed on the transparent layer, the overlapping width of the orientation control projection to the colored portion located below the orientation control projection is Since it is 1/4 or less of the diameter of the alignment control protrusion, even when the alignment control protrusion is misaligned with respect to the colored portion of the colored pixel of the reflective display, the alignment control protrusion is colorless and transparent. A color filter for a liquid crystal display device in which the height of the alignment control protrusion from the layer does not increase is obtained.

Hereinafter, embodiments of the present invention will be described in detail.
1A and 1B are a plan view and a cross-sectional view of an embodiment of a color filter for a liquid crystal display device according to the present invention. FIG. 1 is an enlarged view of the portion (P) shown in FIG. 9 (a). A colorless transparent layer (47) is formed on the colored portion (45) located below the alignment control projection (Mv). The overlapping width of the orientation control projections (Mv) is set to 1/4 or less of the diameter (φ1) of the orientation control projections (Mv). FIG. 1 shows a state in which the alignment control protrusions (Mv) are formed in the X direction without positional deviation with respect to the colored portion (45) of the colored pixel of the reflective display.

As shown in FIG. 1, in the color filter for a liquid crystal display device according to the present invention, the overlapping width of the alignment control protrusion (Mv) to the colored portion (45) is set to the diameter (φ1) of the alignment control protrusion (Mv). Therefore, the width (W11) of the through-hole portion (46) is larger than the diameter (φ1) of the alignment control protrusion (Mv) (W11> φ1).
An alignment control protrusion (Mv) having a diameter (φ1) is provided above a through hole portion (46) having a width (W11). Therefore, the peripheral edge portion of the alignment control projection (Mv) does not overlap the end portion (45E) of the colored portion (45) on the colorless transparent layer (47).

  Specifically, an alignment control protrusion (Mv) having a diameter (φ1) of 16 μm is provided above a through hole portion (46) having a width (W11) of 24 μm, and overlaps above an end portion (45E) of the colored portion. There is no.

  Further, the surface of the colorless transparent layer (47) in which the through-hole portion (46) is filled with the colorless transparent resin is not flat, and a depression (48) is generated. When the alignment control protrusion (Mv) having the height (T2) is formed on the colorless transparent layer (47) having the depression (48) having the depth (T1), the alignment control from the surface of the colorless transparent layer (47) is performed. The height (T3) of the projection (Mv) is a height that is lower by the depth (T1) of the recess (48) (T3 = T2-T1). The numerical values of T1 to T3 are the same as the numerical values in FIG.

  Specifically, the depth (T1) of the depression (48) is obtained when the colorless transparent layer (47) having a thickness of about 2.0 μm is formed on the colored portion (45) having a thickness of about 1.4 μm. It becomes about 0.2 μm. In FIG. 1, T2 is about 1.6 μm, and T3 is about 1.4 μm. In FIG. 1, the transparent conductive film is omitted.

  FIG. 3 shows the overlapping amount (D) of the alignment control protrusion (Mv) through the colorless transparent layer (47) to the colored portion (45) located below the alignment control protrusion (Mv) and the overlap. It is explanatory drawing which shows the relationship with the variation | change_quantity ((DELTA) T) of the height of the protrusion (Mv) for orientation control to arise. FIG. 3 shows the results obtained by the present inventor in examining the relationship between the amount of overlap (D) on the colored portion (45) and the amount of change in height (ΔT).

As shown in FIG. 3, in the alignment control projection (Mv) having a diameter (φ1) of 16 μm, the fluctuation amount (ΔT) increases as the overlap amount (D) increases, but the overlap amount (D ) No change in height is observed. Between about 4 μm and 8 μm, an increase (˜about 0.17 μm) in the fluctuation amount (ΔT) proportional to the increase in the overlap amount (D) is observed. For the increase in the overlap amount (D) between about 8 μm and 16 μm, the variation amount (ΔT) is about 0.17 to 0.18 μm.
That is, the overlapping width of the alignment control protrusion (Mv) through the colorless transparent layer (47) to the colored portion (45) positioned below the alignment control protrusion (Mv) is equal to the alignment control protrusion (Mv). It was found that if the diameter (φ1) is equal to or less than ¼, the amount of variation (ΔT) in the height of the alignment control protrusion (Mv) caused by the overlap is substantially zero.

FIGS. 2A and 2B show a state in which the alignment control protrusions (Mv) are formed in a position shifted in the X direction with respect to the colored portion (45) of the colored pixel (42Re) in the reflective display. Is. As shown in FIG. 2, a positional deviation (E) in forming the alignment control protrusion (Mv) occurs to the left of the X axis in FIG. For this reason, the peripheral part of the alignment control projection (Mv) is such that the width (D12) overlaps the end part (45E) of the colored part (45) on the colorless transparent layer (47). D12 = [(φ1) 1/2 + E] − [(W11) 1/2].

Specifically, an alignment control protrusion (Mv) having a diameter (φ1) of 16 μm is provided above the through hole portion (46) having a width (W11) of 24 μm with a positional deviation (E) of 8 μm at the time of formation thereof, An overlap of 4 μm in width (D12) occurs above the end (45E) of the colored portion.
However, the height of the alignment control projection (Mv) from the surface of the colorless and transparent layer (47) does not change, and is the same as the height (T3) of the alignment control projection (Mv) shown in FIG. It is. That is, since the overlapping amount of the alignment control protrusion (Mv) is 4 μm, which is 1/4 of the diameter (φ1) of the alignment control protrusion (Mv), there is no variation in height (ΔT = 0).

  The variation in height (ΔT) due to the positional deviation is not added to the variation 0.2 μm of the alignment control projection (Mv) itself. As a result, alignment unevenness occurs in the liquid crystal, and the display quality is not affected.

(A) is a top view of one Example of the color filter for liquid crystal display devices by this invention. (B) is sectional drawing of one Example of the color filter for liquid crystal display devices by this invention. (A) is the top view in which the orientation control protrusion was formed by being displaced in the X direction. FIG. 5B is a cross-sectional view in which the alignment control protrusions are formed to be displaced in the X direction. It is explanatory drawing which shows the relationship between the overlap width of the protrusion for orientation control to a coloring part, and the variation | change_quantity of the height of the protrusion for orientation control which arises by overlap. It is the top view which showed typically an example of the color filter used for a liquid crystal display device. FIG. 5 is a cross-sectional view taken along line X-X ′ of the color filter illustrated in FIG. 4. It is sectional drawing of an example of the color filter used for a transflective liquid crystal display device. It is a fragmentary sectional view of the color filter for liquid crystal display devices in which the photo spacer (projection part) was formed. (A) is explanatory drawing which showed the cross section of MVA-LCD typically. (B) is an enlarged plan view showing one pixel of another example of the color filter for MVA-LCD. (C) is sectional drawing which expands and shows one pixel of the other example of the color filter for MVA-LCD. (A) is a top view of an example of the color filter provided with the through-hole part of reflective display, and the protrusion for orientation control. FIG. 9B is a sectional view taken along line A-A ′ in FIG. (A) is the top view in which the orientation control protrusion was formed by being displaced in the X direction. FIG. 5B is a cross-sectional view in which the alignment control protrusions are formed to be displaced in the X direction. (A) is a top view explaining the height of a hollow and the alignment control protrusion. (B) is sectional drawing explaining the height of a hollow and the alignment control protrusion. It is sectional drawing which expands and represents the part of FIG. It is a fragmentary sectional view which shows a mode that the protrusion for orientation control overlaps with a coloring part.

Explanation of symbols

4, 7, 8, 9 ... color filter 20 ... TFT side substrate 21 ... liquid crystal molecules 22a, 22b, 23 ... alignment control projection 40 ... glass substrate 41 ... black matrix 41A ... Matrix part 41B of black matrix ... Frame part 42 of black matrix ... Colored pixel 42Tr ... Colored pixel 42Re for transmissive display ... Colored pixel 43 for reflective display ... Transparent conductive film 44 Ps ... Photo spacer 45 ... Colored portion 45E ... Colored portion end 46 ... Through-hole portion 47 ... Colorless transparent layer 48 ... Colorless transparent layer recess 80 ... MVA- LCD
93... Orientation control projections D 1, D 2, D 12 with a circular planar shape E. Overlapping width E of orientation control projections E. Position shift Mv when forming orientation control projections M ... Orientation control projections Px ... one pixel area Re ... reflective display area T1 ... dent depth T2 ... height T3 of the alignment control protrusion ... the alignment control protrusion from the surface of the colorless transparent layer Height T5: Photo spacer height T6: Height of photo spacer from colorless transparent layer T7: Difference in height between photo spacer and first alignment control protrusion ΔT: For alignment control Height variation amount due to protrusion misalignment Tr... Transmissive display area W1... Through-hole width W11... Through-hole width c in the present invention. ... Diameter of orientation control protrusion

Claims (1)

On a glass substrate, at least a colored pixel for transmissive display, a colored pixel for reflective display, a colorless transparent layer on the colored pixel for reflective display, and a colorless transparent layer above the through-hole portion constituting the colored pixel for reflective display An alignment control protrusion having a circular planar shape is formed , and the peripheral edge of the alignment control protrusion formed on the depression of the colorless transparent layer generated by filling the through hole overlaps the end of the colored pixel. In the color filter for a liquid crystal display device, the overlapping width of the alignment control protrusion to the colored portion located below the alignment control protrusion is ¼ or less of the diameter of the alignment control protrusion. Color filters for liquid crystal display devices.

Images