Surgery – Means for introducing or removing material from body for... – Treating material introduced into or removed from body...
Reexamination Certificate
2000-09-27
2003-06-10
Dawson, Glenn K. (Department: 3763)
Surgery
Means for introducing or removing material from body for...
Treating material introduced into or removed from body...
C604S131000
Reexamination Certificate
active
06575936
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a liquid infusion apparatus, and more particularly, relates to a liquid infusion apparatus having a driving means for infusing liquid by pushing a plunger into a syringe.
BACKGROUND ART
FIG. 1
shows a conventional liquid infusion apparatus having a driving means comprising a CPU
1
, a motor driving circuit
2
, a potentiometer output processing circuit
3
, an encoder output processing circuit
4
, a motor
5
, gears
6
, a feed screw
7
, a carriage
8
, a slider
9
(plunger pushing out portion), a rotary encoder
10
, a potentiometer
13
, a hook
11
for operating the potentiometer
13
, a wire
12
, a syringe
14
, and a plunger
15
. In said conventional infusion apparatus shown in
FIG. 1
, the syringe
14
having the plunger
15
therein is mounted stationarily. The feed screw
7
is arranged in parallel with said syringe
14
, connected to the motor
5
through the gears
6
, and brought into engagement with the carriage
8
. The slider
9
is connected to the carriage
8
and brought into engagement with an end of the plunger
15
. The rotary encoder
10
is connected to the motor
5
or the feed screw
7
. The potentiometer
13
is arranged at a position in parallel with the feed screw
7
. The hook
11
is connected to an end of the wire
12
for rotating said potentiometer
13
and arranged so as to engage with the carriage
8
when the carriage
8
is moved to a remaining liquid quantity small section. The output of the rotary encoder
10
is applied to the CPU
1
through the encoder output processing circuit
4
and processed. The output of the potentiometer
13
is applied to the CPU
1
through the potentiometer output processing circuit
3
and processed. The motor is driven by a signal from the CPU
1
through the motor driving circuit
2
, so that the plunger
15
is pushed out at a predetermined speed through a predetermined length to exhaust the liquid in syringe
14
.
A further or second conventional liquid infusion apparatus shown in the Japanese Patent Application Laid-Open No. 42218/93 comprises a driving means for driving a plunger of a syringe to move at a predetermined speed between a first and a second positions, and a first linear encoder arranged between a third and fourth positions corresponding to the first and second positions, respectively, for detecting the absolute position and the moving distance of said plunger.
FIG. 2
shows the essential portion thereof.
In the first conventional apparatus, no actual feeding quantity of the carriage can be detected in case that a slip is generated about the feed screw or the motor, or the carriage is floated on the feed screw, and no actual position of the remaining liquid quantity small section can be detected in case that the wire is cut, or the contact of the electric terminal of the potentiometer is failure. Further, in the second conventional apparatus, such problems that the actual feeding quantity of the carriage can not be detected because of the slip about the feed screw or the motor, or of the floatation of the carriage on the feed screw can be solved, because in the second conventional apparatus, the moving state of the carriage is detected by the linear encoder. However, the second conventional apparatus has such a problem that the linear encoder for detecting the absolute value is expensive and the skill is required. Accordingly, an object of the present invention is to provide a liquid infusion apparatus having a driving means which can detect exactly and control the movement of the plunger so as to solve the above problems.
Further, Japanese Patent Application Laid-Open No. 44390/88 discloses an improved liquid infusion apparatus comprising a feed screw to be driven by a prime mover, and a slider movable linearly, wherein the slider is brought into engagement with said feed screw so as to push out a plunger in a syringe and to exhaust liquid in the syringe, and a pressure exerted on the plunger by the slider is detected and compared with a reference value to generate a warning signal.
In said liquid infusion apparatus, a pressure sensor is provided at a plunger pushing portion of the slider and an output of the sensor is compared with a plurality of reference values so as to generate the warning signal and to carry out safely the infusion. As shown in
FIG. 3
, however, in said liquid infusion apparatus an end of the plunger is brought into contact simply with the slider, and accordingly in case that the plunger is sucked into the syringe by an attractive force due to the negative pressure applied to the syringe, the slider is brought into disengagement with the plunger, so that the liquid infusion cannot be attained, but such state cannot be detected. Accordingly, the other object of the present invention is to provide a liquid infusion apparatus which can detect the negative pressure applied to the plunger.
FIGS. 4A and 4B
are views explaining the operation of the other conventional liquid infusion apparatus.
FIG. 4A
shows such a state that the syringe
14
and the plunger
15
are not yet mounted on the main body of the apparatus.
FIG. 4B
shows such a state that the syringe
14
and the plunger
15
are mounted on the main body. In
FIGS. 4A and 4B
, a reference numeral
14
-
1
denotes a flange of the syringe
14
, a reference numeral
15
-
1
denotes a flange of the plunger
15
. A reference numeral
16
denotes a slider,
16
-
1
denotes a holding member provided at the slider
16
for holding the flange
15
-
1
of the plunger
15
,
16
-
2
denotes a pushing portion of the slider
16
,
16
-
3
denotes a grooved portion formed on the holding member
16
-
1
, and
17
denotes a lever of a slider unlock means (not shown). A reference numeral
17
-
1
denotes a push button of the lever
17
,
17
-
2
denotes a pivot shaft of the lever
17
,
21
denotes a main body of the liquid infusion apparatus, and
21
-
1
denotes a groove provided at the main body
21
for receiving therein the flange
14
-
1
of the syringe
14
. In order to install the syringe
14
and the plunger
15
to the main body
21
of the liquid infusion apparatus shown in
FIG. 4A
, the slider
16
is disengaged from the feed screw
7
by pushing the pushing button
17
-
1
of the lever
17
, the slider
16
is moved toward the flange
15
-
1
of the plunger
15
, and the pushing portion
16
-
2
is brought into contact with an outer end of the plunger
15
, so that the syringe
14
and the plunger
15
are fixed to the main body
21
as shown in FIG.
4
B. The width of the grooved portion
16
-
3
is determined corresponding to the maximum thickness of the flange
15
-
1
of the plunger
15
.
In the above conventional apparatus, however, the width of the grooved portion
16
-
3
of the holding member
16
-
1
is fixed, and accordingly, if the thickness of the flange
15
-
1
of the plunger
15
is smaller than that of the grooved portion, the plunger
15
cannot be held positively by the slider
16
.
Further, in a liquid infusion apparatus wherein the liquid infusion is carried out automatically by moving the plunger of the syringe using a motor, it is necessary absolutely to prevent the plunger from moving in a (suction) direction contrary to the pushing direction of the plunger. Accordingly, in the conventional liquid infusion apparatus, the rotary direction of the motor is limited to only one direction by a motor driving program and an electric circuit thereof.
Recently, however, most of electric appliances generate many kinds of electric noises (electromagnetic waves) according to the development of the electronic systems, so that many problems of wrong operation due to the noises have been encountered in the field of the medical services.
Further, Japanese Utility Model Application Laid-Open No. 89053/83 discloses an improved liquid infusion apparatus comprising a feed screw driven by a prime mover, and a slider movable linearly, engaged with the feed screw so as to push out the plunger of the syringe and infuse liquid from the syringe, wherein the en
Hayashi Shigeo
Kojima Seiji
Miura Hiromu
Tominaga Katumi
Dawson Glenn K.
Japan Servo Co. Ltd.
Maynard Jennifer
Patterson, Thuente, Skaar & Christensen LLC
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