Title: Personal injector for liquid medicine
Abstract: Personal injector for liquid medicine comprises a housing provided with needle-mounting part, medicine container holder and connecting port to a personal computer; plunger arranged in housing; electric motor for driving plunger; limit switch for limiting the forward movement of plunger; starting point sensor for detecting return of plunger to the starting point; and substrate having display and mode-select switch mounted thereon. The plunger is movable between the starting point and forward limit point. Limit switch is arranged at the forward limit point. When limit switch is turned on, motor drives plunger in reverse to move it to the starting point thereof.
Patent Number: 6,913,591 Issued on 07/05/2005 to Itoh, et al.
| Inventors:
|
Itoh; Takehito (Osaka, JP);
Kobayashi; Susumu (Osaka, JP);
Tomita; Hideyuki (Osaka, JP)
|
| Assignee:
|
Nipro Corporation (Osaka-fu, JP)
|
| Appl. No.:
|
095713 |
| Filed:
|
March 13, 2002 |
Foreign Application Priority Data
| Mar 15, 2001[JP] | 2001-073883 |
| Current U.S. Class: |
604/67 |
| Intern'l Class: |
A61M 031/00 |
| Field of Search: |
128/DIG 1,DIG.12,DIG.13
222/327,386
604/207,208,156,232,67
|
References Cited [Referenced By]
U.S. Patent Documents
| 4950246 | Aug., 1990 | Muller.
| |
| 5593390 | Jan., 1997 | Castellano et al.
| |
| 5662612 | Sep., 1997 | Niehoff.
| |
| 5690618 | Nov., 1997 | Smith et al.
| |
| 5928201 | Jul., 1999 | Poulsen et al.
| |
| 6004285 | Dec., 1999 | Sugahara.
| |
| Foreign Patent Documents |
| 0 293 958 | Jul., 1988 | EP.
| |
| 0 362 484 | Nov., 1990 | EP.
| |
Primary Examiner: Mendez; Manuel
Attorney, Agent or Firm: Birch, Stewart, Kolasch & Birch, LLP
Claims
1. A personal injector for liquid medicine comprising:
a housing having a distal end and a proximal end and including a needle-mounting
part, a medicine container holder, and a connecting port to a computer;
a plunger arranged in said housing and adapted to be longitudinally moved between
a starting point and a forward limit point within the housing;
an electric motor for driving said plunger;
a limit switch arranged at the forward limit point to stop the forward movement
of said plunger;
a starting point sensor for detecting return of the plunger to the starting point;
and
a substrate arranged in said housing and provided with a display, a mode-select
switch, and a confirmation switch;
wherein the confirmation switch confirms an on-state of the starting point sensor,
a set mode of the injector, and a notice of an administration of the liquid medicine,
and
wherein said plunger is adapted to be moved to the starting point by the reverse
driving of the motor when said limit switch is turned on.
2. The personal injector according to claim 1, wherein said limit switch is turned
on when a desired dosage is greater than a residual liquid medicine content.
3. The personal injector according to claim 1,
wherein said motor is driven to move the plunger to a forward limit point where
the limit switch is turned on, in case that a desired dosage is greater than a
residual liquid medicine content and an operation mode is set to an additional
dosage mode, thereby calculating and displaying a difference between the desired
dosage of the liquid medicine and an actual dosage of the liquid medicine to determine
an additional desired dosage.
4. The personal injector according to claim 1, wherein said injector is adapted
to detect clogging of a needle attached to the needle-mounting part.
5. The personal injector according to claim 1, wherein said housing is provided
with a battery holder for holding a battery and with a power switch.
6. The personal injector according to claim 1, wherein said housing is provided
with a connector for a power source.
7. The personal injector according to claim 1, wherein said plunger is provided
with a manual dial which allows the user to manually move the plunger forward.
8. The personal injector according to claim 1, wherein said medicine container
holder is provided with a medicine container detect switch for detecting presence
of the medicine container.
9. The personal injector according to claim 1, wherein a rotary motion of the
electric motor is converted into a rotary motion of a ball screw, which is then
converted into a longitudinal linear motion of the plunger.
10. The personal injector according to claim 1, wherein the electric motor is
adapted to cause the plunger move in either a forward or a backward longitudinal
linear motion.
11. The personal injector according to claim 4, further comprising a strain gauge
arranged between the electric motor and the housing.
12. The personal injector according to claim 1, wherein the mode select switch
includes a mode switch M for displaying an additional dosage mode on the display
when a desired dosage is judged to be greater than a residual content of the liquid
medicine, a plus-signed switch for a user to push in case the additional dosage
is required, and a minus-signed switch for the user to push in case the additional
dosage is not required.
13. The personal injector according to claim 12, wherein pushing the push-signed
switch activates the motor to start the administration of the liquid medicine.
14. The personal injector according to claim 12, wherein pushing the minus-signed
switch turns on the limit switch, and drives the motor in reverse.
15. A personal injector for liquid medicine comprising:
a housing having a distal end and a proximal end and including a needle-mounting
part, a medicine container holder, and a connecting port to a computer;
a plunger arranged in said housing and adapted to be longitudinally moved between
a starting point and a forward limit point within the housing;
an electric motor for driving said plunger;
a limit switch arranged at the forward limit point to stop the forward movement
of said plunger;
a starting point sensor for detecting return of the plunger to the starting point;
and
a substrate arranged in said housing and provided with a display and a mode-select
switch;
wherein the mode select switch includes a mode switch M for displaying an additional
dosage mode on the display when a desired dosage is judged to be greater than a
residual content of the liquid medicine, and
wherein said plunger is adapted to be moved to the starting point by the reverse
driving of the motor when said limit switch is turned on.
16. The personal injector according to claim 15, the mode select switch further
comprises a plus-signed switch for a user to push in case the additional dosage
is required, and a minus-signed switch for the user to push in case the additional
dosage is not required.
17. The personal injector according to claim 16, wherein pushing the push-signed
switch activates the motor to start the administration of the liquid medicine.
18. The personal injector according to claim 16, wherein pushing the minus-signed
switch turns on the limit switch, and drives the motor in reverse.
19. The personal injector according to claim 15, the substrate being provided
with a confirmation switch for confirming an on-state of the starting point sensor,
a set mode of the injector, and a notice of an administration of the liquid medicine.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a personal injector for liquid medicine. More
particularly, the invention relates to a simplified injector for liquid medicine,
which is intended for patients who have chronic diseases and require self-administration
of liquid medicines, and which enables the user to administer a dose of liquid
medicine with ease in safety as well as to perform automatic injection and control
of the administration.
Conventionally, pen-type liquid drug injectors have been used for
administration of liquid medicines, for example, insulin to diabetic patients.
Such a drug injector generally comprises a body provided with a dosage-setting
dial, an injection button, a piston and unit-setting indicator; a medicine container
holder and a cap. In use, the administration of insulin is carried out by a method
comprising the steps of inserting a cartridge into a medicine container holder
of the body, fitting a needle on a tip of the body, injecting the liquid medicine
for air-release and confirmation of fluid communication, and setting a dosage of
the liquid medicine.
However, the liquid medicine injectors of the conventional pen-type have
the following disadvantages: When the cartridge has been emptied, the user may
have the false impression that the injector got out of order. The injection of
the setting dosage can not be confirmed since the injection of the liquid medicine
is carried out only while the injection button is pushed. The given dose can not
be quantified accurately since the liquid medicine may drip down when the needle
is accidentally taken out from the skin during administration. The correct control
of administration can not be performed since the residual liquid medicine content
is not expressed numerically.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made under such circumstances to provide a personal
injector for liquid medicine, which makes it possible to automatically and simply
perform injection and medication control.
Another object of the present invention is to provide a personal injector
for liquid medicine, which makes it possible to administer a dose of liquid medicine
with ease in safety.
To this end, the personal injector for liquid medicine of the present invention
is so designed as to be connected to a computer, provided with a limit switch for
stopping the forward movement of a push member or a plunger at a forward limit
point, wherein the plunger is adapted to be returned to its starting point by reverse
drive of a electric motor when the limit switch is turned on.
According to the present invention, there is provided a personal injector
for liquid medicine comprising:
- a housing having a distal end and a proximal end and including a needle-mounting
part, a medicine container holder, and a connecting port to a computer;
- a plunger arranged in said housing and adapted to be longitudinally
moved by said motor between a starting point and a forward limit point within the housing;
- an electric motor for driving said plunger;
- a limit switch arranged at the forward limit point to stop the forward
movement of said plunger;
- a starting point sensor for detecting return of the plunger to the starting
point; and
- a substrate arranged in said housing and provided with a display and
mode-select switch; and
- wherein said plunger is adapted to be moved to the starting point by
reverse driving of the motor when said limit switch is turned on.
In case that the desired dosage is greater than a residual liquid medicine content
of the cartridge, and operation mode is set to non-additional dosage mode, the
limit switch may be adapted to be turned on. In case that the desired dosage is
greater than the residual liquid medicine content, and that operation mode is set
to an additional dosage mode, the motor may drive the plunger until it reaches
to the forward limit point where the limit switch is turned on and a difference
between the desired dosage and the actually injected amount of the liquid medicine
may be calculated to set it as an additional desired dosage as well as to display
it on the display.
Preferably, the personal injector may be provided with means for detecting
a clogging of a needle attached to the needle-mounting part. The housing may be
provided with a battery holder for holding a battery to use the battery as a power
source. Alternatively, the housing may be provided with a connector adapted to
be connected to an external power source. When using the battery, the housing is
preferably provided with a power switch. Preferably, the plunger is provided with
a manual dial so that the plunger is manually moved in case of battery shutoff,
electric power failure or trouble in the circuit. The medicine container holder
may be provided with a cartridge detect switch for detecting presence of the cartridge.
In order to prevent wrong operation, the housing may be provided with a confirmation
switch adjacent to the mode select switch for confirmation of the selected operation
mode and the starting point sensor being "on". The housing may be provided with
an alarm which is activated when the needle clogging is detected or when the plunger
is returned to the starting point, and which is deactivated when the confirmation
switch is pushed.
The present invention will become more fully understood from the detailed description
given hereinbelow and the accompanying drawings, which are given by way of illustration
only, and thus are not limitative of the present invention.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIG. 1 is a plan view of a personal injector for liquid medicine according to
the present invention;
FIG. 2 is a bottom view thereof;
FIG. 3 is a schematic illustration of an internal structure of the injector
shown in FIG. 1;
FIG. 4 is a schematic illustration of an internal structure of the injector
shown in FIG. 1;
FIG. 5 is a schematic block diagram of the injector according to the present invention;
FIG. 6 is a flow chart showing operation of the injector according to the present invention;
FIG. 7 is a flow chart showing operation of the injector according to the present
invention; and
FIG. 8 is a flow chart showing operation for detection of a needle clogging.
DETAILED DESCRIPTION OF THE INVENTION
As illustrated in FIGS. 1 to
4, a personal injector for liquid medicine
comprising a housing
1 provided with a needle-mounting part
11, a
medicine container holder
12 and a connecting port
13 to a personal
computer not illustrated in the drawings; a plunger
2 arranged in the housing
1; an electric motor
3 arranged in the housing for driving the plunger
2; a limit switch
4 for limiting the forward movement of the plunger
2; a starting point sensor
5 for detecting return of the plunger
2 to the starting point; and a substrate
6 provided with a display
61 and a operation mode-select switch
62. The plunger
2 is
movable between a starting point and a forward limit point.
The limit switch is arranged at the forward limit point of the plunger
2.
If the limit switch
4 is turned on, the motor
3 drives the plunger
2 in the reverse direction to move it to the starting point thereof.
The housing
1 is a box-shaped member having a distal end and a proximal
end and is provided at the distal end thereof with the needle-mounting part
11.
The housing
1 is further provided with the connecting port
13 to
a personal computer at a suitable position thereof. The electric motor
3
is arranged in the housing
1 and serves as means for driving the plunger
2. The medicine container holder
12 is arranged in the housing
1
adjacent to the needle mounting part
11 and on the distal side thereof.
The plunger
2 is movably arranged in the housing
1 on the distal
side of the medicine container holder
12. The needle (not shown) attached
to the needle mounting part
11, medicine container holder
12 and
plunger
2 are arranged on the same longitudinal axis. Numeral
131
designates a cap for connector port to the personal computer,
141 is a cover
for battery case,
17 is a cover to be opened or closed when operating the
movable dial,
18 is a support used for placing the injector on a desk or
optional place.
In the embodiment illustrated in FIGS. 1-4, a cartridge (not illustrated) is
inserted
into the medicine container holder
12 through the distal end of the housing
1. However, it may be set in the medicine container holder
12 by
opening a cover of the housing
1. In case of that the injector is of a type
wherein a cartridge (one form of a cartridge) is inserted into the medicine container
holder from the distal end, the medicine container holder
12 is formed in
the form of a hollow cylinder and partially protruded from the distal end of the
housing
1, as illustrated in FIGS. 1-4.
The needle-mounting part
11 is a cap-like member with a through-hole
111
at a top plane thereof and is removably fitted on a protruded portion
121
of the medicine container holder
12 in the proper way such as, for example,
screw engagement. When installing the cartridge
12 into the injector, the
needle-mounting part
11 is removed first from the protruded portion
121
of the medicine container holder
12 and screwed again on the protruded portion
121 after inserting the cartridge into the medicine container holder
12.
Thus, the needle-mounting part
11 pushes the cartridge in the medicine container
holder
12 at a top plate thereof. This means that the needle-mounting part
11 provides a function of positioning the cartridge since the cartridge
is pushed by a top plate of the needle-mounting part. The through-hole
111
may take any desired size, provided that it is smaller than the- diameter of the
cartridge but sufficiently greater than an outer diameter of a canula of the needle.
In order to improve the portability, the housing
1 may be provided with
a battery holder
14 as illustrated in FIGS. 3 and 4 to use a battery as
a power source for the injector. However, the housing
1 may be provided
with an external power receptacle (not shown) to use the external power source
as the power source. Further, the housing
1 may be provided with both battery
holder
14 and the external power receptacle to use then selectively. When
the injector is so designed as to use any battery, it is preferred to provide a
power switch
15 at the proximal end of the housing
1 to save power consumption.
The plunger
2 is a hollow cylindrical member having an internal thread
23 and a flanged portion
22 provided at the proximal end thereof.
On the proximal end of the flanged portion
22, there is provided a protrusion
221 protruded radially from the flanged portion
22 so as to come
into contact with the starting point sensor
5 and limit switch
4.
The plunger
2 is screw-mounted on a ball screw
8 and adapted to be
driven by the motor
3. By activating the motor
3, a rotatory motion
thereof is converted into the rotatory motion of the ball screw
8, which
is then converted into a longitudinal linear motion of the plunger
2 engaged
at the internal thread
23 thereof with the ball screw
8. Thus, the
plunger
2 is moved forward or backward along the longitudinal axis of the
ball screw
8. The proximal end
22 of the plunger
2 may be
provided with a manual dial
21 to allow the user to manually drive the plunger
2 in case of unexpected situations such as battery shutoff, electric power
failure or trouble in the circuit.
The plunger
2 is driven by the motor
3 from the starting point
where the protrusion
221 comes into contact with the starting point sensor
5 to the forward limit point where the protrusion
221 comes into
contact with the limit switch
4, or vice versa. When the limit switch
4
is turned on, the motor
3 drives the ball screw
8 in the reverse
direction until the plunger
2 is returned back to the starting point. The
limit switch
4 is positioned at the forward limit point for the plunger
2 and turned on when the protrusion
221 comes into contact therewith
or when a desired dosage is greater than the residual liquid medicine content in
the cartridge and the operation mode has been set to a non-additional dosage mode.
The starting point sensor
5 is positioned at the starting point and turned
on to stop the backward movement of the plunger
2 when the plunger
2
is returned to the starting point and comes into contact with the starting point
sensor
5 at the protrusion
221 thereof. A micro switch or a software
switch generally constitutes the limit switch
4. It is preferred to use
a micro switch and a software switch together. A micro switch generally constitutes
the starting point sensor
5.
Preferably, the injector is provided with means for detecting any clogging
of the needle attached to the needle-mounting part
11, to avoid any trouble
of the motor
3 resulting from the clogging of the needle. Means for detecting
any clogging of the needle comprises a strain gauge
7 arranged between the
motor
3 and the housing
1 to detect a small strain occurred in the
motor
3. Another means for detecting any clogging of the needle comprises
means for detecting the revolution of the motor or a moving velocity of the plunger
2. In this case, the clogging of the needle is detected by comparing a normal
value of the revolution of the motor or a moving velocity of the plunger
2
to an actual revolution or moving velocity measured during operation of the injector.
If the actual value is lower than the normal value, the needle is determined as
being clogged up. Another means for detecting any clogging of the needle comprises
a load cell attached to the plunger
2 to detect a stress from the plunger
2. In this case, the needle is determined as being clogged up when the stress
exceeds a certain set value. The term "needle" used herein includes needles having
a tube, such as winged catheters.
If the plunger
2 is positioned at the starting point, turning on the power
switch
15 activates the motor
3 even when the cartridge is not held
in the medicine container holder
12. In order to avoid such erroneous behavior,
it is preferred to provide a mean for detecting presence of the medicine container
in the medicine container holder
12. To this end, the medicine container
holder
12 is provided with a container-detecting switch
16 which
is turned on by setting the medicine container in the medicine container holder
12 to allow the motor
3 to be activated only when the cartridge is
set correctly in the medicine container holder
12.
The substrate
6 has a display
61, a mode-select switch
62
and a control unit (not shown) mounted thereon. The mode select switch
62
is adapted to allow the user to set a desired dosage, medication records, the kind
of alarm (sounds, flashing caution signal, etc.), loudness level or length of sound
(when the alarm is set to sound), need for additional dosage and the like. The
display
61 is adapted to display the time for next administration, a residual
volume of liquid medicine, an additional dosage and other necessary information
in addition to the operation mode set by the mode-select switch
62. The
information or data except for those set by the mode select switch
62 are
input by a personal computer electrically connected to the injector through the
connecting port
13. As the display
61, it is preferred to use a liquid
crystal display. The substrate
6 may be provided with a confirmation switch
63 adjacent to the mode select switch
62 to confirm on-state of the
starting point sensor, set mode of the injector, notice of administration and the
like. This enables to prevent erroneous use of the injector. The housing
1
may be provided with an alarm (not shown) which is activated at the time of detection
of the clogging of the needle, or at the time of return to the stating point of
the plunger
2, and deactivated by pushing the confirmation switch
63.
The alarm may be constituted by one element selected from the group consisting
of light emitting diodes for flashing caution signal, buzzers and chimes. The injector
may be provided with all of these alarms to allow the user to optionally select
one or more of these elements.
The control system for the injector of the present invention will be explained
below with reference to the accompanying drawings.
As illustrated in FIG. 5, the control system includes a microprocessor (MPU)
adapted
to control the alarm (ALM), display
61 through a display control circuit
611 and motor
3 through a motor control circuit
31. The microprocessor
MPU is adapted to receive and process information sent from the power switch
15,
confirmatory information sent from the confirmation switch
63, mode select
information sent from mode select switch
62, information sent from the limit
switch
4 and starting point sensor
5, information sent from the clogging-detect
means
7, and control information sent from the motor control circuit. The
additional amount of the medicine is calculated by MPU, determined and displayed
as a difference between a desired dosage and an actual dosage of the medicine.
When turning on the power switch
15, the control system is activated
and is ready to accept an information, as illustrated in FIG.
6. If the
actual time is reached to a set time for administration (step
1), the microprocessor
MPU gives notice to the user by alarm and, if necessary, displays message on the
screen of the display
61 (step
2). The notice of administration is
held for a certain period, for example, 5 to 10 seconds. By pushing the confirmation
switch
63 (step
3), the MPU displays relationship between a desired
dosage and a residual liquid medicine content of the cartridge. If the desired
dosage is equal to or smaller than the residual content (step
4), the motor
3 is activated to perform injection of the medicine (step
6). After
completing injection of the desired dosage of the medicine (step
8), the
operation of MPU varies with the conditions of the injector. If the desired dosage
is judged at step
4 as being smaller than the residual content, MPU activates
the alarm (step
13) as illustrated in FIG.
7. By pushing the confirmation
switch
63, the MPU stops the alarm (step
17) and terminates the operation
for administration of the liquid medicine.
On the other hand, if the desired dosage is judged at step
4 as being
equal
to the residual content, the plunger
2 reaches to the forward limit point
and turns on the limit switch
4 (step
9), whereby completing the
administration of the desired dosage of the liquid medicine. Simultaneously therewith,
the MPU displays an additional dosage on the screen of the display
61 as
being zero (step
10) and activates the motor
3 in reverse (step
11).
Thus, the plunger
2 is moved backward and returned to the starting point.
When the plunger
2 has reached to the starting point, the starting point
sensor
5 is turned on by the plunger
2 (step
12) and the alarm
is activated by MPU (step
13). By replacing the consumed cartridge with
new one (step
14) or pushing the confirmation switch
63 (step
16),
the alarm is stopped (step
15 or step
17), thereby completing the
operation of administration.
If the desired dosage is judged as being greater than the residual content (step
4), the user is requested to push a mode switch (M) of the mode select switch
62 to display an additional dosage mode on the screen of the display
61.
At this point, it is sufficient for the user to push either a plus-signed switch
(+) in case of the additional dosage being required or a minus-signed switch (-;)
in case of no additional dosage being required (step
5). By pushing the
plus-signed switch, the motor
3 is activated to start administration of
the liquid medicine. During the administration of the liquid medicine, the plunger
2 reaches the forward limit point and turns on the limit switch
4
(step
7). Simultaneously therewith, the MPU displays the additional dosage
on the screen of the display
61 as illustrated in FIG.
7 and activates
the motor
4 in reverse (step
11). Thus, the plunger
2 is moved
backward and returned to the starting point. When the plunger
2 reaches
the starting point, the starting point sensor
5 is turned on (step
12)
and the alarm is activated by MPU (step
13). By replacing the consumed cartridge
with new one (step
14), the alarm is stopped (step
15). By pushing
the confirmation switch
63 (step
3), the administration of additional
dosage is started in the same manner as mentioned above for the case where the
desired dosage is judged as being smaller than the residual content.
If the minus-signed switch is pushed (step
5), the limit switch
4
is turned on (step
9) and the motor
4 is driven in reverse (step
11), as illustrated in FIG.
7. Thus, the plunger
2 is moved
backward and returned to the starting point. At this point, the starting point
sensor
5 is turned on (step
12) and the alarm is activated by MPU
(step
13). By replacing the consumed cartridge with new one (step
14),
the alarm is stopped (step
15). By pushing the confirmation switch
63
(step
3), the administration of the desired dosage is started in the same
manner as mentioned above for the case where the desired dosage is judged as being
smaller than the residual content.
As will be understood from the above, the personal injector of the present invention
makes it possible to automatically and simply perform injection and medication
control. Further, the personal injector of the present invention makes it possible
to administer a dose of liquid medicine with ease in safety by provision of clogging-detect
means and the manual operating dial.
The invention being thus described, it will be obvious that the same may be varied
in many ways. Such variations are not to be regarded as a departure from the spirit
and scope of the invention, and all such modifications as would be obvious to one
skilled in the art are intended to be included within the scope of the following claims.
*
