Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-11-06
2003-05-06
Gordon, Raquel Yvette (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06557980
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an image forming apparatus applied to a copying machine, a facsimile, a printer and the like, and more particularly, to an image forming apparatus controlling a toner flying from a toner carrier to a back surface electrode using toner passing control means controlled in response to an image signal, and applying the toner to image receiving means positioned between the toner passing control means and the back surface electrode, thereby forming images.
BACKGROUND ART
In recent years, with the improvements in the performance of personal computers and the development of the network technology, there has been a strong demand for printers or copiers having processing capability high enough for printing a large amount of documents and also color documents. However, such image forming apparatuses capable of outputting high quality monochrome or color documents at a satisfactory level and a high processing speed are much in demand and yet still under development.
As one such technique, an image forming technique according to so-called “toner jet (registered trademark)” method is known. According to the method, a toner is let to fly onto image receiving means such as recording paper and an image carrying belt by the effect of an electric field for forming images.
The apparatuses disclosed by Japanese Patent Publication No. 44-26333, U.S. Pat. No. 3,689,935 (see Japanese Patent Publication No. 60-20747), and Japanese Patent Republication No. 9-500842 are known as the image forming apparatuses of this kind. The apparatus disclosed by Japanese Patent Application No. 10-100780 will be now described in conjunction with
FIG. 6
by way of illustration.
In
FIG. 6
, a grounded toner carrier
31
carries and transports a charged toner, while a restriction blade
32
controls the toner on the toner carrier
31
into one to three layers and charges the toner. A supply roller
33
supplies the toner to the toner carrier
31
and charges the toner. Toner passing control means
34
is provided with a toner passing hole
35
around which a control electrode
36
is provided. A voltage corresponding to an image signal is applied to the control electrode
36
from a control power supply
37
. Reference numeral
38
denotes a back surface electrode and
39
denotes a back surface electrode power supply. Reference numeral
40
denotes image receiving means such as recording paper transported on the back surface electrode
38
.
In the above-described structure, as the supply roller
33
and the toner carrier
31
are operated to form an even toner layer on the toner carrier
31
with the restriction blade
32
and the toner layer is transported, a voltage is applied to the back surface electrode
38
. Meanwhile, the image receiving means
40
is moved, and a voltage corresponding to an image signal is applied by the control power supply
37
such as a driving IC to the control electrode
36
in synchronization with the movement, so that the toner on the toner carrier
31
is allowed to pass the toner passing hole
35
and fly in response to the image signal and stick on the image receiving means
40
. Thus, a desired image is formed on the image receiving means
40
.
In order to form a fine image of 600 dpi (dots per inch) on the entire surface of the image receiving means
40
, for example, the toner passing control means
34
must be provided with the toner passing holes
35
at such a pitch. Meanwhile, the holes inevitably cannot be arranged in a single row, and therefore as shown in
FIG. 8
, the toner passing holes
35
and the control electrodes
36
are arranged in a plurality of rows (eight rows in the figure). The toner passing hole
35
and the control electrode
36
are circular, and connection electrodes electrically connected to the control electrodes
36
are provided to extend on both sides in the moving direction of the toner carrier
31
in order to prevent mutual interference, and each connected to a lead in the driving IC outputting the control voltage.
Note that in
FIG. 6
, as an example of the constitution, the image receiving means
40
is composed of recording paper or the like, and an image is formed directly thereon, while the recording paper could vary in thickness, easily change in the property depending on the humidity, and easily deform during the transportation. In case of a color printer, the varying transportation of the recording paper makes it difficult to achieve synchronization in the timing of forming an image in each color, which could cause problems such as degradation in the image quality. Therefore, as disclosed by Japanese Patent Application No. 10-100780, an intermediate image carrying belt may preferably be used as the image receiving means
40
and the image formed on the image carrying belt may be transferred altogether onto recording paper in some cases.
The constitution above is now described in conjunction with FIG.
7
. Reference numeral
43
denotes an endless type image carrying belt as the image receiving means
40
, and the belt is made of a film produced by scattering a conductive filler within resin and having a resistance of about 10
10
Ù·cm, and wound around between a pair of rollers
44
a
and
44
b
. A pickup roller
45
feeds a recording paper sheet
46
on a one-sheet-basis from a paper feed tray, a timing roller
47
synchronizes the fed recording paper sheet
46
and the image position, and a transfer roller
48
transfers a toner image formed on the image carrying belt
43
onto the recording paper sheet
46
. The transfer roller is pressed toward the roller
44
a
with the image carrying belt
43
interposed therebetween and applied with a transfer voltage. A fixing device
49
heats and presses the recording paper sheet
46
having the toner image transferred thereon for fixing the toner image on the recording paper sheet
46
.
With the image forming apparatus of this kind, in order to form dots about as small as 100 &mgr;m, for example, the small holes in the print head must be about as small as 100 &mgr;m, so that the small holes could clogged up and resultant dots could be thinned or dots are not formed at all. This phenomenon occurs because in addition to the clogging of the small holes with dust scattered in the apparatus, the small holes may be clogged with a developer used for forming images as well. The deposited developer or foreign substances affect an electric field formed by the control electrode, or mechanically prevents the developer from passing, so that resultant dots are thinned or dots are not formed at all. Therefore, some cleaning means is necessary for the print head.
As conventional means for cleaning the small holes, there are a method of using an electric field or an air flow as well as a method of providing ultrasonic vibration to the print head which allows effective cleaning of a developer which is not charged or a developer solidified within the small holes for example as suggested by Japanese Patent Publication No. 3-57658.
According to the disclosure of Japanese Patent Publications No. 4-164659 and No. 5-77479, a developer passing control member having small holes and control electrodes is attached with a vibration generator providing vibration and the vibration forms an advancing wave propagating the developer passing control member so that all the small holes can evenly be cleaned. For the purpose, a vibrating member is secured along the row of small holes in the developer passing control member and a vibration generator is coupled to one end of the vibrating member.
Another conventional image forming apparatus employs a direct marking method according to which an image is directly formed on a recording member. An image forming apparatus disclosed by Japanese Patent Publication No. 44-26333 is a developer injection type apparatus according to one of such direct marking methods. According to the direct marking method, an image signal is input to a control electrode provided at a print head to cause an accelerated electric field, a charged developer is allowed
Fukano Akira
Ito Taichi
Kitahara Takuya
Kitaoka Yoshitaka
Kumon Akira
Jordan and Hamburg LLP
Matsushita Electric - Industrial Co., Ltd.
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