JP4415525B2 - Color filter for reflective color display and reflective color display including the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a color filter for a reflective color display and a reflective color display including the same.
[0002]
[Prior art]
In contrast to a transmissive LCD (Liquid Crystal Display), which has a backlight on the back and controls the emission of light with a liquid crystal panel, a reflective LCD that controls the reflected light of ambient lighting (ambient light) has low power consumption and direct sunlight. It has come to be used mainly for portable information terminals because of its good visibility below. In recent years, a display using a display principle different from that of an LCD has been reported, and is expected as a reflection type color display having a feature not found in an LCD.
[0003]
The display principle of the LCD is currently TN (Twisted Nematic) and STN (Super Twisted Nematic), which are mainly used. Furthermore, IPS (In-Plane Switching), MVA (Multi-domain Vertical AlignBumps) A method such as Birefringence has also been reported. Each method itself controls the light transmission state, and the color cannot be changed. Therefore, it is necessary to use a color filter in order to perform color display.
[0004]
As another display method instead of LCD, an electrophoretic method in which charged fine particles are moved by an electric field (Japanese Patent No. 2551785), and a twist ball method in which a sphere divided into two colors is rotated by an electric field (Japanese Patent No. 2860790). Publication), a polymer-dispersed liquid crystal system (PDLC Polymer Dispersion Liquid Crystal) (JP-A-2001-92383), in which the alignment state inside the liquid crystal droplets dispersed in the resin is controlled by an electric field, and the resin component ratio is small There is a polymer network liquid crystal system (PNLC Polymer Liquid Crystal) (Japanese Patent Laid-Open No. 2001-154219) in which a polymer has a network structure in liquid crystal. In these cases, the scattering reflection state is controlled by an electric field, and it is difficult to display a color by itself, and it is practical to use a color filter.
[0005]
In addition, cholesteric liquid crystals that use selective reflection according to the helical pitch of the liquid crystal have been reported. However, when color display by selective reflection is attempted, a three-layer stacked structure is adopted, and the structure is complicated and manufactured. Therefore, it is conceivable to place a color filter on one cholesteric layer that reflects white.
[0006]
In any case, in order to effectively use environmental light that is not as bright as the backlight, it is required to increase the aperture ratio of the color filter itself as much as possible. In the color filter for transmissive LCD, a light-shielding part called a black matrix is provided in an area other than the pixel part in a grid pattern or a net pattern in order to improve the contrast of the screen, but the aperture ratio is lowered by the black matrix. In a type color display, it is desirable not to provide a black matrix as much as possible.
[0007]
[Problems to be solved by the invention]
However, it is difficult to manufacture a color filter without a black matrix so that the color filter patterns of the respective colors are in contact with each other only at the end portions, resulting in a decrease in yield and an increase in cost. In addition, although it is possible to form the color filter pattern end portions of each color little by little, the light transmittance of the overlapped portion is extremely lowered and is the same as that of the black matrix. become.
[0008]
When the color filter patterns of each color are in contact with each other or overlapped, display particles in the vicinity of the color filter pattern, for example, electrophoresis microcapsule particles, not only the electric field from the electrode corresponding to the color filter pattern, It is considered that the display is adversely affected by the electric field from the adjacent electrode.
[0009]
On the other hand, if the color filter patterns of the respective colors are arranged with a large space between them, the portion becomes so-called light omission and color omission, which is considered undesirable.
As described above, in the color filter for the reflection type color display, there has been no clear guideline in the design in the case where the black matrix is not provided.
[0010]
The present invention has been made under the circumstances as described above, and for a reflective color display excellent in brightness and contrast, which prevents light leakage and color loss and increases the aperture ratio without using a black matrix. An object is to provide a color filter.
Another object of the present invention is to provide a reflective color display having such a color filter.
[0011]
[Means for Solving the Problems]
The present inventors have conducted research in view of the above problems, and as a result, even if there is a certain gap between the color filter patterns of each color, no light leakage or color loss occurs, and the aperture ratio is reduced. It has been found that a bright display screen can be obtained by increasing the number. The present invention has been made based on such findings.
[0012]
That is, the present invention provides a color filter comprising a first substrate having a predetermined pattern of electrodes, and a plurality of colored layers disposed opposite to the first substrate and formed at positions corresponding to the electrode patterns. In a color filter for a reflective color display, comprising: a second substrate having a color difference; and a display medium interposed between the first and second substrates, a black matrix is provided between the colored layers of the color filter. In other words, a portion of the display medium in a corresponding position between the electrode patterns can be driven by a leakage electric field of the electrodes, and a portion of the display medium in the vicinity of each colored layer is provided. For reflective color displays, which are in a range not affected by the display characteristics due to the electric field from the electrode adjacent to the electrode corresponding to each colored layer To provide a color filter.
[0013]
According to the present invention, in a color filter for a reflective color display including a plurality of colored layers arranged in a predetermined pattern, no black matrix is provided between the colored layers of the color filter, and 1 μm or more and 20 μm. Provided is a color filter for a reflective color display, characterized in that the following gap is provided.
[0014]
Furthermore, the present invention provides a color filter comprising a first substrate having a predetermined pattern of electrodes, and a plurality of colored layers disposed opposite to the first substrate and formed at positions corresponding to the electrode patterns. In a reflective color display comprising a second substrate having a color difference and a display medium interposed between the first and second substrates, no black matrix is provided between the colored layers of the color filter, The distance between the electrode patterns can be driven by the leakage electric field of the electrodes, and the portions of the display medium in the vicinity of the colored layers can be connected to the colored layers. The reflective color display is characterized in that it is in a range that is not affected by the display characteristics due to the electric field from the electrode adjacent to the electrode.
[0015]
Furthermore, the present invention provides a color comprising a first substrate having a predetermined pattern of electrodes and a plurality of colored layers disposed opposite to the first substrate and formed at positions corresponding to the electrode patterns. In a reflective color display comprising a second substrate having a filter and a display medium interposed between the first and second substrates, no black matrix is provided between the colored layers of the color filter, In addition, a reflective color display having a gap of 1 μm or more and 20 μm or less is provided.
[0016]
The present invention includes an electrophoretic reflection type color display, a twist ball reflection type color display, a polymer dispersion type liquid crystal type reflection color display, a polymer network type liquid crystal type reflection color display, and a single-layer cholesteric liquid crystal type reflection type. It can be applied to a reflective color display such as a color display. Among these, an electrophoretic reflective color display and a twisting ball reflective color display that scatter-reflects on the surface of the display medium are more preferable because the influence of the parallax due to the cell thickness is impossible in principle. As the electrophoretic reflective color display, a microcapsule electrophoretic display can be suitably used.
[0017]
The color filter of the present invention configured as described above and the reflective color display including the color filter have a high aperture ratio because the color layers are spaced apart from each other without using a black matrix, and thus a bright display screen. In addition, since the interval is limited to a predetermined range, it is possible to obtain a display screen with high contrast and no light omission or color omission.
[0018]
The color filter and reflective color display of the present invention can be applied regardless of the type of base material such as a glass substrate, a resin substrate, or a resin film.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a reflective color display according to an embodiment of the present invention.
[0020]
In FIG. 1, a display substrate 3 is interposed between a back substrate formed with a pixel electrode 2 on a glass substrate 1 and a front substrate formed with a color filter pattern 5 and a transparent electrode 6 on a glass substrate 4. A reflective color display is formed by interposing and bonding. As the display medium 3, electrophoretic particles, twist balls, polymer dispersed liquid crystal, polymer network type liquid crystal, single layer cholesteric liquid crystal, or the like can be used.
[0021]
The color filter pattern 5 is composed of colored layers of a plurality of colors, for example, red (R), green (G), and blue (B), and is arranged at a position corresponding to the pixel electrode 2. A predetermined interval is provided between the colored layers of the color filter pattern 5, and no black matrix is provided there.
[0022]
As described above, when the color filter patterns of the respective colors are overlapped, the overlapping portion performs the same operation as the black matrix, and the aperture ratio is reduced. On the other hand, as shown in FIG. 1, when a space is provided between the colored layers of the color filter pattern 5, it has been generally considered that light leakage occurs and the contrast is lowered.
[0023]
However, according to the study by the present inventors, the portion of the display medium 3 in the region that should not be driven by the electric field of the electrode at the corresponding position between the pixel electrodes 2 is shown by the arrow in FIG. It was found that the display was driven by changing the state according to the leakage electric field from the adjacent electrode. It was found that the width of the region where the state is changing is approximately 20 μm although it depends on the display method and the distance between the electrodes.
[0024]
Therefore, even if the space between the color filter patterns is spaced with the width of change of the state of the display medium due to the leakage electric field from the adjacent electrode as an upper limit, no light leakage occurs and the contrast does not decrease.
[0025]
Specifically, the inter-electrode region having a width of 20 μm or less was in a black state during black display, a white state during white display, and a gray state in other states. It is an advantage in the reflective color display to actively use this area without hiding it with a black matrix or the like. This is because the aperture ratio is very high because there is no black matrix, and the brightness of the screen can be increased by the white state of the inter-electrode region during white display.
[0026]
During black display, this inter-electrode region is also in a black state, so that no problem occurs. When other colors are displayed, the inter-electrode area is gray, as if it were an extremely fine black matrix, but the gray color is dark gray when the adjacent pixels are bright and dark when dark. In this case, no problem occurs.
[0027]
On the other hand, when the interval between the colored layers of the color filter pattern 5 is too narrow, the display medium in the vicinity of the colored layer is affected not by the electrode corresponding to the colored layer but by the electric field from the adjacent electrode, and the display characteristics. Will be adversely affected. The interval at which such a phenomenon occurs is approximately 1 μm although it depends on the display method and the distance between the electrodes. That is, it was found that the lower limit of the interval between the color filter patterns was about 1 μm.
[0028]
As described above, in the color filter of the present invention, the interval between the color filter patterns is generally 1 μm or more and 20 μm or less, and preferably 5 μm or more and 10 μm or less.
[0029]
【Example】
Examples of the present invention and comparative examples are shown below to describe the present invention more specifically. The present invention is not limited to these.
[0030]
<Example 1>
A dispersion in which titanium oxide particles having a particle size of 0.1 μm and carbon black particles having a particle size of 0.1 μm are dispersed in an organic solvent as white particles and black particles, respectively, is sealed in urea resin, and the microparticles having a particle size of 100 μm are sealed. Capsules were formed.
[0031]
Next, as shown in FIG. 2A, the microcapsules are densely spread on the pixel electrode 12 having a predetermined pattern formed on the glass substrate 11 to form a microcapsule layer 13, which is used as a back substrate. .
[0032]
On the other hand, as shown in FIG. 2B, a color filter 15 having a stripe pattern of three colors of R, G, and B was formed on the glass substrate 14 by photolithography. At this time, an interval of 10 μm was provided between the color filter patterns 15 of the respective colors, and no black matrix was formed. An ITO (Indium Tin Oxide) layer 16 having a thickness of about 1000 mm was provided as a transparent electrode on the color filter 15 to form a front substrate.
[0033]
2B and the rear substrate shown in FIG. 2A are bonded together so that the color filter pattern 15 on the front substrate and the pixel electrode pattern 12 on the rear substrate overlap. A microcapsule type electrophoretic reflection type color display as shown in FIG.
[0034]
When a predetermined voltage was applied between the electrodes of the reflection type color display thus obtained, white, black, red, blue, green, and others were displayed. As a result, a bright display was obtained and the contrast was high.
[0035]
<Example 2>
A microcapsule electrophoretic reflection type color display was produced in the same manner as in Example 1 except that the interval between the color filter patterns of each color was set to 5 μm.
[0036]
When white, black, red, blue, green, and others are displayed by applying a predetermined voltage between the electrodes of the reflective color display thus obtained, a bright display can be obtained as in the first embodiment. The contrast was high.
[0037]
<Comparative Example 1>
A microcapsule electrophoretic reflective color display was produced in the same manner as in Example 1 except that a black matrix having a line width of 10 μm was provided between the color filter patterns of the respective colors.
[0038]
By applying a predetermined voltage between the electrodes of the reflection type color display thus obtained, it was possible to display white, black, red, blue, green and others. Black was fine, but the screen was darker for the other colors.
[0039]
<Comparative example 2>
A microcapsule electrophoretic reflective color display was produced in the same manner as in Example 1 except that the color filter patterns of the respective colors were provided so as to overlap each other with a width of 10 μm at the end.
[0040]
By applying a predetermined voltage between the electrodes of the reflection type color display thus obtained, it was possible to display white, black, red, blue, green and others. Black was fine, but the screen was darker for the other colors.
[0041]
<Comparative Example 3>
A microcapsule electrophoretic reflective color display was produced in the same manner as in Example 1 except that the color filter patterns of the respective colors were provided so as to be in contact with each other at the end.
[0042]
By applying a predetermined voltage between the electrodes of the reflection type color display thus obtained, it was possible to display white, black, red, blue, green and others. However, the white and bright color displays were darker than in Example 1.
[0043]
<Comparative example 4>
A microcapsule-type electrophoretic reflection type color display was produced in the same manner as in Example 1 except that the color filter patterns of the respective colors were provided with an interval of 25 μm.
[0044]
By applying a predetermined voltage between the electrodes of the reflection type color display thus obtained, it was possible to display white, black, red, blue, green and others. However, the display was lower in contrast than Example 1.
[0045]
In the above examples and comparative examples, examples of application to a microcapsule type electrophoretic display have been described. However, the present invention relates to a twist ball type reflective color display, a polymer dispersed liquid crystal type reflective color display, and a polymer. The same effect can be obtained when applied to a reflective color display such as a network-type liquid crystal reflective color display or a single-layer cholesteric liquid crystal reflective color display.
[0046]
In the above description, the color filter is formed on the front substrate and the transparent electrode is formed thereon. However, the present invention is not limited to this, and the color filter is formed directly on the display medium formed on the rear substrate side. It is also possible to do.
[0047]
【The invention's effect】
As described above in detail, according to the present invention, since the interval between the colored layers is provided without using the black matrix, the aperture ratio is high, so that a bright display screen can be obtained. Provided is a color filter for a reflective color display and a reflective color display including the same, which are capable of obtaining a display screen with high contrast without light loss or color loss because of being limited to a predetermined range. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a reflective color display according to an embodiment of the present invention.
2 is a cross-sectional view showing a microcapsule type electrophoretic display according to Example 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,4 ... Glass substrate 2 ... Pixel electrode 3 ... Display medium 5 ... Color filter pattern 6 ... Transparent electrode

Claims (2)

A first substrate having an electrode of a predetermined pattern, and a second substrate having a color filter made of a colored layer of a plurality of colors disposed opposite to the first substrate and formed at a position corresponding to the electrode pattern And a color filter for a microcapsule type electrophoretic reflection type color display comprising a display medium comprising a microcapsule layer interposed between the first and second substrates, between the colored layers of the color filter. The black matrix is not provided, and an interval is provided. The interval is such that the portion of the display medium at a position corresponding to the pattern of the electrodes can be driven by the leakage electric field of the electrodes, and in the vicinity of each colored layer. 1 μm or more so that the display medium is not affected by display characteristics due to the electric field from the electrode adjacent to the electrode corresponding to each colored layer. Microcapsule electrophoresis method reflective color color filter for a display, wherein the 0μm in the range of less. A first substrate having an electrode of a predetermined pattern, and a second substrate having a color filter made of a colored layer of a plurality of colors disposed opposite to the first substrate and formed at a position corresponding to the electrode pattern And a microcapsule-type electrophoretic reflection type color display comprising a microcapsule layer interposed between the first and second substrates, a black matrix is provided between the colored layers of the color filter. An interval is provided without being provided, and the interval is such that the portion of the display medium in a position corresponding to the pattern of the electrodes can be driven by the leakage electric field of the electrodes, and the portion of the display medium near each colored layer However, in the range of 1 μm or more and 20 μm or less so that display characteristics are not affected by the electric field from the electrode adjacent to the electrode corresponding to each colored layer. A microcapsule type electrophoretic reflection type color display characterized by being.

Images