Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
1998-10-20
2001-10-16
Chapman, Mark (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S110100
Reexamination Certificate
active
06303255
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an organic EL panel (organic electroluminescence panel) and a method of manufacturing the same.
2. Description of the Prior Art
A method of manufacturing an inorganic EL panel disclosed in Japanese Unexamined Patent Publication No. 5-108014 will be described as a conventional example. According to this example, as shown in
FIG. 1
, a mask
18
having a window pattern corresponding to the emission film portions for pixels of a display color is disposed near a panel substrate
1
on which a transparent electrode film
2
and an insulating film
16
are formed. In this state, emission layers
17
of the same display color are selectively formed simultaneously at positions of the window pattern by vacuum deposition. Hence, emission portions of different display colors are sequentially formed at different positions in units of colors.
Japanese Unexamined Patent Publication No. 7-121056 discloses a method of manufacturing the color filter of a plasma display or liquid crystal display. According to this method, a substrate formed with a photosensitive body layer having an organic photoconductive layer is charged to desired polarity, and is selectively exposed to form a latent image. Then, toner is attached to this substrate to form a pattern. This substrate is calcined to remove the organic photoconductive layer, thereby obtaining a desired pattern.
As a method of manufacturing the color filter of a liquid crystal display, a pigment dispersing method utilizing photolithography is also known. According to this method, a substrate is coated with a photoconductive polymer dispersed with a color pigment, and is exposed through a photomask. After that, this substrate is developed and etched to form a color pattern. This method is repeated for each of red, green, and blue.
With the above method of sliding the mask in accordance with the colors, the substrate deforms or deflects due to the weight of the mask or thermal expansion caused by radiation heat during deposition, and fine positional control of the mask is difficult to perform. Therefore, the layers overlap each other and insufficient separation occurs easily. Also, it is difficult to form a large-size screen. To obtain a mask, a pattern is formed in a thin metal plate by photoetching. The finer the pattern is, the more easily the pattern is disconnected, making it difficult to fabricate the mask itself. In order to prevent short-circuiting of the respective pixels, the mask and the substrate must be separated from each other. However, the deposition material rounds about during deposition, and accordingly further shrinkage in device geometries is limited.
Since an organic EL panel uses an organic material having no heat resistance as the material of an emission layer, a hole transport layer, and the like, it cannot employ the method of which uses a photosensitive body and develops toner dispersed with an inorganic pigment and calcines the toner to remove the photosensitive body. Since a white electroluminescent material is not currently available for an organic EL panel, it is difficult to utilize a color filter.
Assume that the pigment dispersing method is applied to a color organic EL panel. In this case, the organic EL panel which is very weak against water utilizes a wet process for patterning wherein a photosensitive polymer is applied to the substrate, is exposed through a photomask, and is developed and etched. Accordingly, generation and growth of a dark spot, and generation of a pixel defect due to separation of an organic layer-cathode interface, readily occur.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation in the prior art, and has as its object to provide an organic EL panel in which damage to the organic EL panel is small and which attains a smaller feature size and colored with a simple method, and a method of manufacturing the same.
In order to achieve the above object, according to the first aspect of the present invention, there is provided a method of manufacturing an organic EL panel in which an organic electroluminescent material is formed between a pair of opposing electrodes at least one of which is transparent or opaque, wherein an emission pixel is obtained through the steps of forming a photoconductor having a charge generation layer and a charge transport layer on a transparent electrode side, charging the photoconductor and thereafter exposing the photoconductor to form an electrostatic latent image at an emission pixel portion, developing the electrostatic latent image by using toner kneaded with an electroluminescent medium, and fixing the toner on the photoconductor after development.
According to the second aspect of the present invention, there is provided a method of manufacturing an organic EL panel in which an organic electroluminescent material is formed between a pair of opposing electrodes at least one of which is transparent or opaque, wherein an emission pixel is obtained through the steps of forming a photoconductor having a charge generation layer and a charge transport layer on a transparent electrode side, charging the photoconductor and thereafter exposing the photoconductor to form an electrostatic latent image at a portion other than an emission pixel portion, developing the electrostatic latent image by using toner kneaded with an electroluminescent medium, forming an emission layer portion by deposition while using a developed portion as a mask, and removing the toner from a panel substrate after deposition to obtain the emission pixel.
In this manner, with the organic EL panel manufacturing method according to the present invention, an organic photoconductor is formed on a transparent electrode formed on a transparent substrate, e.g., a glass substrate, and is charged. The photoconductor is selectively exposed in a prospective pixel pattern portion to form an electrostatic latent image. Then, toner kneaded with an organic electroluminescent medium is applied on the electrostatic latent image, thereby forming a pixel pattern. Alternatively, an organic photoconductor formed on the transparent electrode side is charged and exposed to form an electrostatic latent image at a portion other than the prospective emission pixel. The electrostatic latent image is developed using toner. An emission layer portion is formed by deposition while using the developed portion as the mask. After that, the toner is removed from the panel substrate, thereby obtaining an emission pixel. The pixel pitch and space width of the panel obtained are determined by the exposure precision and toner particle diameter; a micropattern having a size of as small as about 10 &mgr;m can be formed.
With the above method, when a thin film is formed by vacuum deposition using the mask, roundabout caused by mask floating does not take place. Consequently, color misregistration or misalignment does not occur, and a panel having a sharp edge can be fabricated. Since mask alignment need not be performed to decrease the vacuum process, the speed of the panel fabricating process can be increased.
As is apparent from the above aspects, according to the present invention, an organic photoconductor is formed on the transparent electrode, and is selectively exposed and developed to form an emission pattern. When compared to a method wherein masking is used in vacuum deposition, which is conventionally employed in an organic EL, roundabout of the material or insufficient separation caused by distortion or misalignment of the mask is eliminated, and a high size precision and positional precision can be ensured.
The resolution of the emission pattern depends on the exposing unit and the particle diameter of the toner. Hence, the device geometries can be reduced to a level of as small as about 10 &mgr;m.
Since an emission/electron transport material and the like are dispersed in a binder, the adhesion properties of the respective interfaces of the layers increase to eliminate cohesion of the mate
Iketsu Yuichi
Sakaguchi Yoshikazu
Chapman Mark
NEC Corporation
Young & Thompson
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