Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2000-09-29
2002-03-05
Goodrow, John (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S126200, C399S329000, C399S335000
Reexamination Certificate
active
06352807
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to printers and, more particularly, to an image forming method and apparatus having a photoreceptor web which can be directly heated.
2. Description of the Related Art
In general, an image, forming apparatus such as a liquid electro-photographic printer, as shown in
FIG. 1
, includes a photoreceptor web
10
that circulates and is supported by a plurality of support rollers
11
, and a plurality of laser scanning units
12
, a plurality of development units
13
, a drying unit
17
and a transfer unit
19
, which are sequentially arranged in a direction that the photoreceptor web
10
proceeds. The laser scanning units
12
and the development units
13
are alternately installed. The laser scanning units
12
scan light onto the photoreceptor web
10
to form an electrostatic latent image. Each of the development units
13
develops the electrostatic latent image with a predetermined developer to form a developed image, and includes a developing roller
14
for developing the electrostatic latent image, and a squeegee roller
15
for squeegeeing the developed developer so that the liquid carrier is removed from the developer. The drying unit
17
includes a drying roller
16
for drying the carrier remaining on the photoreceptor web
10
. The transfer unit
19
includes a transfer roller
18
for transferring the image passing through the transfer unit
19
to a sheet of print paper P.
In the above structure, the developer that is developed by the development unit
13
comprises ink which is a mixture of a powdered toner having a predetermined color and a liquid carrier that works as a solvent. The developer is supplied to a development gap G between the photoreceptor web
10
and the developing roller
14
. The developer is moved to the electrostatic latent image due to a difference between the level of electric potential applied to the developing roller
14
and that of the electrostatic latent image. Toner of the ink used for the development is made filmy by the squeegee roller
15
and becomes a toner image while most of the carrier is squeegeed and removed. The small amount of carrier remaining on the photoreceptor web
10
is dried by the drying unit
17
.
In the above image forming process, the efficiency of squeegeeing the carrier with the squeegee roller
15
greatly affects not only the quality of the toner image which is formed to be filmy, but also the performance of the drying roller
16
and the transfer roller
18
. For example, since the amount of carrier to be dried by the drying unit
17
decreases as the efficiency of squeegeeing by the squeegeeing roller
15
is improved, the time for drying carrier can be reduced. When the carrier drying time decreases, the number of consecutively printed papers increases. Also, the life span of the drying roller
16
and the transfer roller
18
extends.
Studies to improve the efficiency of squeegeeing have been widely made. There has been a recent report that the efficiency of squeegeeing is closely related to the glass transfer temperature Tg of ink or temperature of the photoreceptor web
10
. It is widely known that a glass transfer temperature value of −1 Tg is an appropriate value. The efficiency of squeegeeing increases as the value is lower than −1 Tg to a degree. However, according to the results of various experiments, when the glass transfer temperature is lowered under −10 Tg, many problems are generated. For example, there is wash-off in which the filmy toner image is developed by another developing unit for another color and partially lost; dry picking in which the toner image is tore off by the drying roller
16
; and transfer error in which the toner image is not completely transferred to the print paper and remains on the transfer roller
18
as a latent image.
A method to improve the squeegeeing efficiency is to constantly maintain the temperature of the photoreceptor web
10
. For this purpose, a conventional heating apparatus is used which includes an additional heating means (not shown) for indirectly heating the photoreceptor web
10
, a temperature detecting sensor (not shown) for measuring the temperature of the photoreceptor web
10
, and a means for preventing overheating. However, the apparatus has drawbacks because the number of parts is increased which complicates the structure and raises the cost. Also, since the heat loss is continuously generated from the photoreceptor web
10
due to the ink, the temperature of the photoreceptor web
10
cannot be constantly maintained.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a photoreceptor web and an image forming apparatus and method having an improved structure in which the temperature of the photoreceptor web can be constantly maintained by directly heating the photoreceptor web so that the efficiency of squeegeeing and drying is improved.
Accordingly, to achieve the above objective, there is provided a photoreceptor web for an image forming apparatus which comprises a base layer having a front and rear surface, a conductive ground layer formed on the front surface of the base layer, and a photosensitive layer formed on the ground layer, where an electrostatic latent image is formed by scanned light. The invention further includes a first protective layer formed on the photosensitive layer, which protects the photosensitive layer, and a heating layer formed on the rear surface of the base layer in a predetermined pattern, which receives electric power and generates resistance heat, wherein the photoreceptor web is maintained at a constant temperature by the resistance heat generated by the heating layer.
It is preferred in the present invention that the first protective layer comprises a barrier layer formed on the photosensitive layer, which prevents intrusion of foreign materials into the photosensitive layer, and a release layer formed on the barrier layer, where an image is formed.
It is also preferred in the present invention that a pair of power terminals, which receive the electric power, are exposed at each of both side portions of the heating layer.
It is also preferred in the present invention that the photoreceptor web further comprises a second protective layer coated or positioned on a surface of the heating layer to prevent damage to the heating layer.
Further, it is preferred in the present invention that the second protective layer is formed of a material selected from the group consisting of silicon, polyamide and polyethylene.
To achieve another aspect of the present invention, there is provided an image forming apparatus which comprises a photoreceptor web supported by a plurality of support rollers, which is operative to circulate along a predetermined path, a laser scanning unit, positioned proximate to the photoreceptor web, which scans light onto the photoreceptor web to form an electrostatic latent image, a developing unit, which develops the electrostatic latent image using a developer to form an image, a drying unit, which dries the photoreceptor web, a transferring unit, which transfers the image formed on the photoreceptor web to a printable medium, such as a sheet of print paper, and a power supply unit, which supplies power, which heats the photoreceptor web. Here, the photoreceptor web comprises a base layer, a conductive ground layer formed on the base layer and a photosensitive layer formed on the ground layer, where an electrostatic latent image is formed by the light scanned by the laser scanning unit. A first protective layer is formed on the photosensitive layer, which protects the photosensitive layer, and a heating layer is formed on a rear surface of the base layer in a predetermined pattern, which receives the power from the power supply unit and generates resistance heat, wherein the photoreceptor web is maintained at a constant temperature by the resistance heat generated by the heating layer.
In a preferred embodiment according
An Seung-deog
Kim Wan-ha
Lee Won-hyung
Goodrow John
Samsung Electronics Co,. Ltd.
Sughrue & Mion, PLLC
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