Pumps – Motor driven – Electric or magnetic motor
Reexamination Certificate
2001-02-15
2003-07-29
Freay, Charles G. (Department: 3746)
Pumps
Motor driven
Electric or magnetic motor
C417S474000, C417S477300, C417S477500, C417S477700
Reexamination Certificate
active
06599106
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to a tube pump for generating a pressure by pressing and deforming a tube. More particularly, the invention relates to an ink jet recording apparatus using the tube pump, which is capable of restoring an ink ejection capability of the print head by discharging ink from the print head by utilizing a negative pressure generated by the tube pump. Further, the invention relates to an ink jet recording apparatus which is provided with the tube pump as an ink supplier for supplying ink from a main tank (ink pack) to a sub-tank.
The ink jet recording apparatus is advantageous in that noise generated during the printing operation is low, and small print dots may be arrayed at high density. Because of those advantages, the ink jet recording apparatus has used for a variety of printings, mainly for color printing, recently. The ink jet recording apparatus is provided with an ink jet recording head which receives ink from an ink cartridge, and a paper feeder for moving a recording sheet relatively to the recording head. To print, the ink jet recording apparatus, while moving the recording head, causes the recording head to eject ink drops onto the recording sheet and forms ink dots thereon, in accordance with a print signal.
Thus, the ink jet recording apparatus must unavoidably handle with liquid ink. Accordingly, to prevent the clogging of the nozzle orifices, which is caused by filling of ink to the recording head and volatilization of ink solvent, a process to restore the ink-ejection capability of the recording head is carried out in which ink is forcibly sucked and discharged from the recording head. The forcible discharging of ink, which is performed for removing the nozzle clogging or when air bubbles are left in the recording head, is called a cleaning operation. The cleaning operation is carried out when the recording apparatus, which is not in use for a long time, is operated again, and when the user finds out poor print, such as blur of printed characters, and operates a cleaning switch.
In the cleaning operation, the following sequence of steps is carried out. The recording head is sealingly capped with a capping member, and a negative pressure is applied to the capped head to forcibly discharge ink, by sucking, into the capping member through the nozzle orifices of the recording head. The ink discharged into the capping member is sucked and sent to a used ink tank by the utilization of a negative pressure. Thereafter, the nozzle plate of the recording head is wiped out by a cleaning member formed with an elastic material, e.g., rubber.
A called tube pump has been used for the means for applying a negative pressure into the capping member since it is relatively simple in structure and easy to be reduced in size, and further does not soil the mechanism for sucking and discharging ink. The tube pump will be described in detail with reference to FIG.
31
.
The tube pump
74
includes a pump frame
72
, a pump wheel
70
, and a pair of rollers
71
a
and
71
b
. The pump frame
72
has a tube support surface
76
arcuately defining a configuration of a flexible tube
75
. The pump wheel
70
is rotated by a motive power transmitted from a drive member such as a sheet-feeding motor. A couple of roller support grooves
70
a
and
70
b
are disposed while being radially slanted between an axial direction and a circumferential direction of the pump wheel
70
. The rollers
71
a
and
71
b
are rotatably mounted so that those are movable within and along the roller support grooves
70
a
and
70
b
, respectively.
A pair of guide members
73
a
and
73
b
, made of an elastic material, are disposed at positions facing the pump wheel
70
formed on the pump frame
72
, while extending in the axial direction of the pump wheel
70
.
L-shaped engaging grooves
72
a
and
72
b
are formed in the pump frame
72
. The guide members
73
a
and
73
b
are planted in those engaging grooves
72
a
and
72
b
, respectively.
With such a structure, the guide members
73
a
and
73
b
guide respectively the rollers along the roller support grooves in the rotation backward direction, with rotation of the pump wheel. When the cylindrical body
42
is rotated in the forward direction (direction A), the rollers
71
a
and
71
b
are pushed back by the guide members
73
a
and
73
b
made of the elastic material, respectively. As a result, the rollers
71
a
and
71
b
, respectively, move in the outer circumference direction of the roller support grooves
70
a
and
70
b
, and the flexible tube
75
is compressed flat. Accordingly, a reliability of the pump driving operation is improved.
In the tube pump thus constructed, when the pump wheel
70
is rotated in the forward direction (direction A of an arrow), as shown in
FIG. 31
, the rollers
71
a
and
71
b
move in the outer circumference direction of the roller support grooves
70
a
and
70
b
. Those rollers rotate while pressing the flexible tube
75
flat. As a result, a pressure is generated in the tube and a negative pressure is applied to the capping member. Under the negative pressure, ink is forcibly discharged from the recording head, and the ink discharged into the capping member is sucked and sent to the used ink tank.
Conversely, when the pump wheel
70
is rotated in the reverse direction (direction B of an arrow), the rollers
71
a
and
71
b
move in the inner circumference direction of the roller support grooves
70
a
and
70
b
. As a result, the rollers are put in a release state in which the rollers are in slight contact with the tube. Accordingly, a trouble, e.g., clinging of the tube, is avoided.
The tube pump is used for restoring the ink-ejection capability to cause the recording head to discharge ink therefrom, and also for supplying ink from a main tank, which stores ink therein, to a sub-tank provided in the recording head.
The ink jet recording apparatus, which is used for office or business use, needs an ink cartridge of a large capacity since it handles a relatively large amount of printing. For this reason, a main tank as an ink cartridge (ink pack) is set to a cartridge holder, which is located on the side of the body of the recording apparatus.
The sub-tank is placed on the carriage on which the recording head is mounted. Ink is supplied from the main tank to the sub-tank via an ink supplying tube. Further, ink is supplied from the sub-tank to the recording head.
In this type of the ink jet recording apparatus, the tube pump is used as the ink supplier for supplying ink from the main tank to the sub-tank.
As described above, in the related tube pump, the roller rotates while successively pressing the tube flat. Through the operation, a pressure is generated within the tube to give rise to a negative pressure.
Accordingly, the tube being pressed flat by the rotating roller is restored to its original shape by an elasticity of the flexible tube per se (self-restoring ability).
The thickness (difference between the inner and outer diameters of the tube) of the flexible tube must be secured in a certain level. If the flexible tube is extremely thin, the restoring force is unsatisfactory, and a required suction force cannot be produced.
If the flexible tube is thick, the inner diameter of the tube is small, so that a predetermined quantity of suction cannot be secured. If the inner diameter of the flexible tube is set at a fixed value, the outer diameter is also large, and consequently the whole tube pump is large in size, and hence the ink jet recording apparatus itself is large in size.
Additionally, in the related tube pump, the tube pressed flat restores to its initial state by the elasticity (self-restoring ability) of the tube itself. In this respect, the material which may be used for the tube must be selected from among limited kinds of materials. The metal tube made of aluminum or the like has less elasticity, and hence cannot be used for the tube of the related tube pump.
The elasticity (self-restoring ability) of the tube per se serves as a react
Harada Shuhei
Kobayashi Atsushi
Freay Charles G.
Gray Michael K.
Seiko Epson Corporation
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