Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2002-09-19
2004-10-05
Chowdhury, Tarifur R. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S113000, C349S114000, C349S187000
Reexamination Certificate
active
06801274
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The present invention relates to color filter substrates, methods for manufacturing color filter substrates, liquid crystal devices, and electronic apparatuses, and more particularly, relates to a transflective liquid crystal device which can improve color purity of display in a transmission mode while brightness and color purity of display in a reflection mode are not degraded and which has superior image quality.
2. Description of the Related Art
As liquid crystal devices, there have been known a transmission type liquid crystal device which performs display using light emitted from a backlight embedded therein and a reflection type liquid crystal device which performs display using outside light such as sunlight. The former liquid crystal device has an advantage in that display can be viewed in a dark place where outside light is not sufficient; however, since a backlight is always turned on, there has been a problem in that power consumption is increased. In contrast, the latter liquid crystal device can save power since lighting means is not embedded therein; however, there has been a problem in that it is difficult to view displays in a dark place.
Accordingly, as a liquid crystal device having advantages of the two devices described above, a transflective liquid crystal device has been known in which display is performed in a dark place in a transmission mode using light emitted form a backlight embedded in the device, and in a bright place with sufficient outside light, display is performed in a reflection mode using outside light. In the transflective liquid crystal device, since display can be viewed in a dark place and also in a bright place using outside light, compared to a transmission type liquid crystal device in which a backlight is always turned on, power saving can be performed.
The transflective liquid crystal device has the primary structure comprising a pair of substrates opposing each other, a liquid crystal layer provided therebetween, and transflective layers provided on a surface at the liquid crystal layer side of one of the substrates, which substrate is located at the side opposite to the viewing side. The transflective layer is formed of, for example, a reflection layer having aperture portions, such as slits, formed in respective dots, and in the transflective layer having the structure described above, the aperture portions and a region other than the aperture portions serve as light transmission portions and light reflection portion, respectively. In addition, a transflective liquid crystal device, which comprises color filters provided on one of the substrates and which is capable of performing color display, has also been known. Hereinafter, a substrate provided with color filters is referred to as “color filter substrate”.
In a conventional transflective liquid crystal device, light emitted from a backlight passes through a substrate at the backlight side, a liquid crystal layer, and the substrate at an observer side in that order and is then emitted to the observer side, and by the light described above, display in a transmission mode can be performed. In addition, after passing through the substrate at the observer side and the liquid crystal layer in that order, outside light is reflected from a transflective layer provided on the substrate at the backlight side and is then emitted to the observer side, and by the light described above, display in a reflection mode can be performed.
Accordingly, in a transflective liquid crystal device capable of performing color display, when display is performed in a transmission mode, light incident on a liquid crystal panel passes through the color filter only once and is then emitted to the observer side, and on the other hand, when display is performed in a reflection mode, light incident on the liquid crystal panel passes through the color filter twice before and after being reflected from the transflective layer and is then emitted to the observer side.
As the color filter, a color filter comprising pigment dispersion color portions having red (R), green (G), and blue (B) colors has been widely used. In FIG.
20
(
a
), examples of spectral characteristics (the relationship between wavelength of visible light (light having a wavelength of 400 to 700 nm) incident on the liquid crystal panel and transmittance thereof) of the individual color portions of the pigment dispersion color filter are shown. In FIG.
20
(
a
), R, G, and B show examples of spectral characteristics of the red color portion, the green color portion, and the blue color portion, respectively. Since the spectral characteristics shown in FIG.
20
(
a
) are obtained when light passes through the color filter once, the data shown in this figure corresponds to the spectral characteristics of the color filter when display is performed in a transmission mode.
As shown in FIG.
20
(
a
), the red, green, and blue color portions forming the color filter are provided so as to primarily allow red light (light having wavelengths centered at and near 650 nm), green light (light having wavelengths centered at and near 550 nm), and blue light (light having wavelength centered at and near 450 nm) to pass therethrough, respectively; however, it is also understood that every color portion allows any light having a visible wavelength to pass therethrough. That is, light passing through each color portion of the color filter includes a part of the light having a wavelength which is not desirably displayed although the amount of said part of the light is small as compared to that of another part of the light having a wavelength which is desirably displayed. This results in lowering color purity.
In addition, since spectral characteristics in the case in which light passes' through the color filter twice, that is, spectral characteristics of the color filter when display is performed in a reflection mode, is the square of the spectral characteristics obtained when light passes through the color filter once, for example, the above spectral characteristics are shown in FIG.
20
(
b
).
As shown in FIGS.
20
(
a
) and
20
(
b
), in the conventional transflective liquid crystal device, the spectral characteristics of the color filter in a transmission mode and that of the color filter in a reflection mode are substantially different from each other, and compared to the case in which display is performed in a reflection mode, display performed in a transmission mode has a problem in that the color purity of display is low (range of color reproducibility is small).
The present invention was made in consideration of the situations described above, and an object of the present invention is to provide a color filter substrate which is to be provided in a transflective liquid crystal device, the color filter substrate being capable of improving the color purity of display in a transmission mode while the brightness and color purity of display in a reflection mode are not degraded, and is to provide a manufacturing method thereof. In addition, another object of the present invention is to provide a transflective liquid crystal device capable of improving the color purity of display in transmission mode while the brightness and color purity of display in a reflection mode are not degraded, and is to provide an electronic apparatus comprising this liquid crystal device.
SUMMARY OF THE INVENTION
Through research of the inventor of the present invention to solve the problems described above, a color filter substrate, a method for manufacturing a color filter substrate, a liquid crystal device (transflective liquid crystal device), and an electronic apparatus described below were invented.
A first color filter substrate of the present invention for forming a liquid crystal panel, comprises a base body; transflective layers provided on the base body, each having light transmission portions and light reflection portions; and color filters on the base body, each including a first color filter formed of c
Chowdhury Tarifur R.
Harness & Dickey & Pierce P.L.C.
Nguyen Hoan
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