Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2003-02-20
2004-11-16
Garrett, Dawn (Department: 1774)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S212000, C428S917000, C427S066000, C313S112000, C313S504000, C257S098000
Reexamination Certificate
active
06818328
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a color conversion filter substrate with good environmental resistance and high productivity for displaying multiple colors with high definition, and to an organic multicolor emitting display device provided with such a filter substrate. More specifically, the present invention relates to a color conversion filter substrate and an organic multicolor emitting display device provided with such a filter substrate for a display of electronic and electric equipment such as an image sensor, a personal computer, a word processor, a television, a fax machine, an audio equipment, a video equipment, a car navigation system, an electric desk top calculator, a telephone, a portable terminal, or an industrial instrument. Especially, the present invention relates to an organic multicolor emitting display device using a color conversion method.
In recent years, the information technology has been diversified. Display devices including solid imaging devices in the information technology have been required to have a better aesthetic appearance, a lighter weight, a thinner thickness and higher performance. A great effort has been made to reduce power consumption and increase a response speed. In particular, many attempts have been made to develop high-definition full-color display devices.
In the second half of the 1980s, an organic electro-luminescence (hereinafter referred to as ‘organic EL’) device with an organic molecule thin-layered structure has been developed as a device having higher contrast, constant-voltage driving, wider angle visibility, and faster response as opposed to a liquid crystal display device. Tang et al. reported that an organic EL formed of stacked thin films of organic molecules showed a high luminance of 1000 cd/m
2
at an applied voltage of 10 V (Appl. Phys. Lett., 51, 913 (1987)). This stacked organic EL luminous device has excellent characteristics such as a wide view angle and a quick response time compared to liquid crystal display devices. After the report by Tang et al., a great effort has been made to develop organic EL luminous devices for a practical use. Attempts have also been made to develop similar devices composed of an organic polymer material.
Since the organic EL luminous device provides a high current density at a low voltage, it is expected to provide higher emission luminance and efficiency as opposed to inorganic EL luminous devices and LEDs. The organic EL display device is expected to have characteristics such as (1) high luminance and high contrast, (2) low driving voltage and high emission efficiency, (3) high resolution, (4) wide angle visibility, (5) high response speed, (6) possibility of increasing definition and providing color displays, (7) reduced weight and reduced thickness, and the like. Thus, the organic EL luminous device is expected to have a better aesthetic appearance, a lighter weight, a thinner thickness and higher performance.
Tohoku Pioneer Corporation has already developed products including vehicle-mounted green monochrome organic EL displays since November 1997. In order to meet the society needs, it is desirable to develop improved organic EL displays that are stable for an extended period of time, respond quickly, and display multiple colors or full colors with high definition.
There have been three major approaches as a method of displaying multiple or full colors with the organic EL display. One of the methods was disclosed in Japanese Patent Publications No. 57-167487, No. 58-147989, and No. 03-214593, in which light emitting elements of the three primary colors (red, green, and blue) are arranged in a matrix form. In this method, it is necessary to arrange three types of light-emitting materials (R, G, and B) in a matrix form with high precision, thereby making it technically difficult to produce and increasing a cost. Further, the three types of light-emitting materials have different life times, thereby shifting a color of the display with time.
As the second approach, in Japanese Patent Publications No. 01-315988, No. 02-273496, and No. 03-194895, a method in which a color filter and a backlight emitting white light are used to display the three primary colors through the filter was disclosed. However, it is difficult to obtain an organic light emitting device emitting the bright white light with a long life, which is necessary for obtaining bright three colors R, G, and B.
As the third approach, in recent years, a color conversion method has been proposed in which a filter is composed of a fluorescent material for absorbing light with a wavelength in a light-emission region of an organic light emitting device, so that the fluorescent material emits fluorescence with a wavelength in a visible light region (Japanese Patent Publications No. 03-152897 and No. 05-258860). In this approach, an organic light emitting device that emits a color other than white can be used. Therefore, it is possible to use an organic light emitting device with higher brightness as a light source. In a color conversion method using an organic light emitting device emitting blue light (Japanese Patent Publications No. 03-152897, No. 08-286033, and No. 09-208944), a frequency of blue light is converted to that of green or red light. A color conversion filter containing a fluorescent material with such color conversion effect may be formed in a high-resolution pattern. Accordingly, it is possible to provide a full-color light emitting display even with weak energy light such as near-ultraviolet light or visible light.
In order to form a pattern of a color conversion filter, a method in which a pattern is formed with a photolithography process after a film of a resist (photosensitive polymer) material containing fluorescent material is prepared by spin-coating has been disclosed in Japanese Patent Publications No. 05-198921 and No. 05-258860. Also, Japanese Patent Publication No. 09-208944 has disclosed a process in which a fluorescent material or fluorescent pigment is dispersed in a basic binder followed by etching the binder with an acid solution.
In general, it is important for a practical color display to possess high-resolution color and long-term stability (as described in Kinohzairyo Vol. 18, No. 2, 96). However, the organic EL luminous devices tend to markedly lose light-emission characteristics such as current-luminance characteristics after a specific period of time.
A major cause of the degraded light-emission characteristics is a growth of dark spots in the light-emitting layer. The dark spots are formed of light-emission defects. When the fluorescent material in the light-emitting layer is oxidized while using or storing the organic EL luminous device, the dark spots grow and spread over the entire light-emitting surface. It is believed that the dark spots are created by oxidation or aggregation of a material constituting a layered device caused by oxygen or moisture in the device. The dark spots grow not only when electricity is conducted but also during storage. In particular, it is believed that (1) the growth is accelerated by oxygen or moisture present around the device, (2) the growth is affected by oxygen or moisture attached to the organic stacked films, and (3) the growth is affected by moisture attached to parts or entered in the device when the device is manufactured.
As shown in
FIG. 2
, in the color conversion multicolor organic EL display, the color conversion filters 2, 3, and 4 are disposed under the transparent electrode 7. As described above, the color conversion filter is formed of a resin containing the colorant for color conversion. Because of thermal stability of the colorant, it is not possible to dry the color conversion filter at a temperature above 200° C. Accordingly, it is likely that the color conversion filters contain moisture from a coating liquid or entered during a pattern-forming process. The moisture in the color conversion filters passes through the polymeric layer to the device while the device is stor
Kawaguchi Koji
Utsumi Makoto
Fuji Electric & Co., Ltd.
Garrett Dawn
Kanesaka Manabu
LandOfFree
Color conversion filter substrate, color conversion type... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Color conversion filter substrate, color conversion type..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Color conversion filter substrate, color conversion type... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3336320