Patent Description:
A syringe pump type liquid medicine administration device for expelling a liquid medicine filled in a cylinder with a plunger and administering the liquid medicine into a living body has been conventionally known. This type of liquid medicine administration device includes a barrel-type cylinder, a gasket placed in the cylinder in a slidable manner, a plunger for advancing the gasket, and a motor serving as a drive source for advancing the plunger (see, for example, <CIT>). It is known that, when the liquid medicine administration device is stored for several months with the gasket being placed inside the cylinder in a state in which a liquid lubricant is applied to the inner peripheral surface of the cylinder or the outer peripheral surface of the gasket in order to allow the gasket to slide inside the cylinder, the sliding resistance of the gasket inside the cylinder is greater in a section (initial sliding section) from when the gasket starts advancing in the cylinder until the gasket advances a predetermined distance, while the sliding resistance is smaller in a section (normal sliding section) following the initial sliding section. A sliding gasket for a cylinder reservoir is known from <CIT>. A prior art administration device is known from <CIT>.

Heretofore, a driving force (thrust) required to advance the plunger by driving of the motor has been very high in the initial sliding section. In order to reliably obtain such high driving force, it is necessary to increase the motor and the battery in size, which may lead to an increase in size of the entire liquid medicine administration device.

The present invention has been made in consideration of such problems, and an object of the present invention is to provide a liquid medicine administration device which prevents an increase in driving force in an initial sliding section and is smaller in size than the conventional one, and an operation method thereof.

One aspect of the present invention provides a liquid medicine administration device for administering a liquid medicine into a living body, the device including: a cylinder filled with the liquid medicine; a gasket placed inside the cylinder in a slidable manner; a liquid lubricant applied to an inner peripheral surface of the cylinder or an outer peripheral surface of the gasket; an advancing mechanism configured to advance the gasket in a distal direction; a drive mechanism including a motor that is configured to drive the advancing mechanism; a battery configured to supply power to the motor; and a control unit configured to control a rotational speed of the motor, wherein an advancing movement of the gasket within the cylinder includes a first movement section from when a part of the gasket starts moving until the gasket entirely starts moving, and a second movement section following the first movement section, and the control unit includes a program set such that one cycle including one continuous rotation and one continuous stop of the motor is repeated two or more times in the first movement section.

According to the liquid medicine administration device described above, the gasket is advanced at intervals in the first movement section that is the initial sliding section of the gasket, whereby, even if the sliding surface of the gasket adheres to the inner peripheral surface of the cylinder due to storage for long periods, the adhering portion is pulled off little by little. Thus, an excessive rise in sliding resistance in the initial sliding section can be suppressed. Accordingly, it is possible to provide a liquid medicine administration device that can prevent an increase in driving force in the initial sliding section and that is smaller in size than the conventional one.

The program may be set such that, in the one cycle, a stop time in which the motor is stopped is <NUM> to <NUM> times an operation time in which the motor is rotated.

According to this configuration, since the stop time of the motor in one cycle is appropriately long, the adhering portion of the gasket can be more reliably pulled off little by little, and an excessive rise in the sliding resistance in the initial sliding section can be further suppressed.

The program may be set such that the stop time of the motor in the one cycle is within a range of <NUM> to <NUM> seconds.

The program may be set such that an advancing speed of the gasket according to calculation in the first movement section is within a range of <NUM> to <NUM>/min.

With this configuration, the driving force required to advance the gasket in the first movement section is sufficiently reduced.

The program may be set such that an estimated advancing distance of the gasket calculated based on a rotation amount of the motor in the one cycle is within a range of <NUM> to <NUM>.

The control unit may include a rotation amount detection sensor configured to detect a rotation amount of the motor, and the program may be set such that, in the one cycle, the rotation of the motor is stopped for a predetermined time when a rotation amount of the motor detected by the rotation amount detection sensor after the motor starts rotating reaches a predetermined value corresponding to the estimated advancing distance of the gasket.

The control unit may control the operation of the motor such that an advancing speed of the gasket in the second movement section is faster than an advancing speed of the gasket in the first movement section.

The present inventor has found that the initial sliding resistance of the gasket in the cylinder differs depending on the moving speed of the gasket, and the initial sliding resistance tends to increase as the moving speed of the gasket is faster, while the sliding resistance afterward does not tend to depend on the moving speed of the gasket. In view of this, the gasket is moved slowly in the first movement section where the initial sliding resistance occurs, and the gasket is moved quickly in the following second movement section. Therefore, the driving force (required thrust) required to advance the gasket in the first movement section is suppressed, whereby a desired administration rate is achieved with an increase in power consumption being prevented.

The motor may be a stepping motor, the control unit may control a frequency of a pulse transmitted to the motor, and the program may be set such that, in the one cycle, the rotation of the motor is stopped for a predetermined time when the number of pulses transmitted to the motor reaches a predetermined value corresponding to the estimated advancing distance of the gasket after the motor starts rotating.

Another aspect of the present invention provides an operation method of a liquid medicine administration device including: a cylinder that is filled with a liquid medicine and includes a liquid lubricant applied on an inner peripheral surface; a gasket placed inside the cylinder in a slidable manner; an advancing mechanism configured to advance the gasket in a distal direction; a drive mechanism including a motor that is configured to drive the advancing mechanism; a battery configured to supply power to the motor; and a control unit including a program to control an operation of the motor, wherein an advancing movement of the gasket within the cylinder includes a first movement section from when a part of the gasket starts moving until the gasket entirely starts moving, and a second movement section following the first movement section, the method including repeating, two or more time, one cycle including one continuous rotation and one continuous stop of the motor in the first movement section.

In the one cycle, a stop time in which the motor is stopped may be <NUM> to <NUM> times an operation time in which the motor is rotated.

The stop time of the motor in the one cycle may be within a range of <NUM> to <NUM> seconds.

The control unit may include a rotation amount detection sensor configured to detect a rotation amount of the motor, and in the one cycle, the rotation of the motor may be stopped when an estimated advancing distance of the gasket calculated based on a rotation amount of the motor detected by the rotation amount detection sensor reaches a value within a range of <NUM> to <NUM>.

Preferred embodiments of a liquid medicine administration device and an operation method thereof according to the present invention will be described below with reference to the accompanying drawings.

A liquid medicine administration device <NUM> according to a first embodiment shown in <FIG> is used for injecting a liquid medicine M into a living body. The liquid medicine administration device <NUM> continuously administers the liquid medicine M filled in a cylinder <NUM> into a living body as a result of a pressing action on a plunger mechanism <NUM> over a relatively long time (for example, about several minutes to several hours). The liquid medicine administration device <NUM> may administer the liquid medicine M at intervals into a living body as well. Examples of the liquid medicine M include protein preparations, narcotic analgesics, and diuretics.

As shown in <FIG>, when the liquid medicine administration device <NUM> is used, a patch-type needle-equipped tube <NUM>, for example, is connected to the liquid medicine administration device <NUM> as an administration tool <NUM>, and the liquid medicine M discharged from the cylinder <NUM> is injected into a body of a patient through the needle-equipped tube <NUM>. The needle-equipped tube <NUM> includes a connector <NUM> connectable to a tip portion 12c of the cylinder <NUM>, a flexible liquid delivery tube <NUM> having one end connected to the connector <NUM>, a patch <NUM> connected to the other end of the liquid delivery tube <NUM> and attachable to a skin S, and a puncture needle <NUM> protruding from the patch <NUM>. The puncture needle <NUM> substantially perpendicularly punctures the skin S. Note that the puncture needle <NUM> may obliquely puncture the skin S as well.

It is to be noted that the administration tool <NUM> to be connected to the liquid medicine administration device <NUM> is not limited to the patch-type needle-equipped tube <NUM> described above. For example, a puncture needle (such as a winged needle) may be connected to the tip of the liquid delivery tube <NUM>. Alternatively, the administration tool <NUM> may be a bent needle connectable to the tip portion 12c of the cylinder <NUM> without passing through the liquid delivery tube <NUM>. In this case, the bent needle is bent by, for example, approximately <NUM>° downwards from the tip portion 12c of the cylinder <NUM> and perpendicularly punctures the skin S in conjunction with affixing (adhering) of the liquid medicine administration device <NUM> to the skin S. In addition, the tip portion 12c of the cylinder <NUM>, the administration tool, and a part of the needle may be inside the cylinder <NUM>, and the tip of the needle may protrude from the cylinder <NUM>. In this case, the needle also perpendicularly punctures the skin S in conjunction with affixing (adhering) of the liquid medicine administration device <NUM> to the skin S.

The liquid medicine administration device <NUM> is provided with the cylinder <NUM> filled with the liquid medicine M, the plunger mechanism <NUM> for expelling the liquid medicine M from the cylinder <NUM>, and a housing <NUM> that houses the cylinder <NUM> and the plunger mechanism. The housing <NUM> houses a battery <NUM> for supplying power necessary for operating the liquid medicine administration device <NUM>, a control unit <NUM> (microcomputer) for performing various kinds of controls of the liquid medicine administration device <NUM>, a speaker (not shown), and the like.

The cylinder <NUM> is formed into a hollow cylindrical shape and has a liquid medicine chamber <NUM> therein. The cylinder <NUM> has a body portion 12a having constant inner and outer diameters in the axial direction thereof and having a proximal end which is open, a shoulder portion 12b having inner and outer diameters reduced in a tapered shape from the tip of the body portion 12a in the distal direction, and the tip portion 12c protruding from the shoulder portion 12b in the distal direction. A liquid medicine discharge opening 12d communicating with the liquid medicine chamber <NUM> is formed in the tip portion 12c. A liquid lubricant LM (for example, silicone oil) is applied to the inner peripheral surface of the cylinder <NUM> (the inner peripheral surface of the body portion 12a).

The cylinder <NUM> is filled with the liquid medicine M in advance. The liquid medicine discharge opening 12d is sealed in a liquid-tight manner by a sealing member <NUM> made of an elastic resin material such as a rubber material or an elastomer material. The sealing member <NUM> is punctured by a needle 18a disposed in the connector <NUM> when the connector <NUM> shown in <FIG> is connected to the tip portion 12c. The sealing member <NUM> is fixed to the tip of the cylinder <NUM> by a cap <NUM> having an opening at the tip.

The plunger mechanism <NUM> includes a gasket <NUM> placed in the cylinder <NUM> in a slidable manner, an advancing mechanism <NUM> for advancing the gasket <NUM> in the distal direction, and a drive mechanism <NUM> having a motor <NUM> for driving the advancing mechanism <NUM>.

The gasket <NUM> is made of an elastic resin material such as a rubber material or an elastomer material, and the outer peripheral portion thereof is in close contact with the inner peripheral surface of the cylinder <NUM> (body portion 12a) in a liquid-tight manner. As a result, the proximal side of the liquid medicine chamber <NUM> is closed in a liquid-tight manner. As shown in <FIG>, a plurality of (two in the illustrated example) annular protrusions 34a protruding outward in the radial direction is provided on the outer peripheral portion of the gasket <NUM> at intervals in the axial direction. The gasket <NUM> is placed in the cylinder <NUM> in a state where the annular protrusions 34a are elastically compressed and deformed by the inner peripheral surface of the cylinder <NUM>. The liquid lubricant LM described above is applied over the entire circumference within at least a range in the axial direction in which the gasket <NUM> slides on the inner peripheral surface of the cylinder <NUM>. The liquid lubricant LM may be applied only to an area around the gasket <NUM> at the initial position and the distal end side in the vicinity thereof. The liquid lubricant LM may be applied to the outer peripheral surface of the gasket <NUM>.

In <FIG>, the advancing mechanism <NUM> is axially movable with respect to the cylinder <NUM> and includes a plunger <NUM> for advancing the gasket <NUM> in the distal direction by pressing the gasket <NUM>, a nut member <NUM> connected to the plunger <NUM> and formed with a female screw, and a feed screw <NUM> formed with a male screw 50a engaging with the female screw on the nut member <NUM>. The plunger <NUM> is a member movable in the axial direction for expelling the liquid medicine M. The gasket <NUM> is connected to the tip of the plunger <NUM>. As the plunger <NUM> advances, the gasket <NUM> is pressed by the plunger <NUM> in the distal direction, so that the gasket <NUM> advances.

The feed screw <NUM> is disposed along the axis of the cylinder <NUM>. The feed screw <NUM> has a large gear 50b which is a driven gear. The male screw 50a of the feed screw <NUM> is formed on the outer peripheral surface distal of the large gear 50b over a predetermined range in the axial direction. As the feed screw <NUM> rotates, the nut member <NUM> moves in the distal direction. At this time, the plunger <NUM> advances by being pushed in the distal direction by the nut member <NUM>. Note that the female screw may be formed on the plunger <NUM> itself without providing the nut member <NUM>.

The drive mechanism <NUM> has the motor <NUM> which is supplied with electric power from the battery <NUM> and driven and controlled under the control action of the control unit <NUM>, and a pinion <NUM> fixed to an output shaft of the motor <NUM> and serving as a drive gear. The pinion <NUM> meshes with the large gear 50b of the feed screw <NUM>.

The motor <NUM> is a rotational drive source that can be rotated faster with an increase in a control frequency and can be rotated slower with a decrease in the control frequency. In the present embodiment, the motor <NUM> is a stepping motor 40A that operates in synchronization with a pulse signal. The stepping motor 40A can control the rotational speed by changing the pulse frequency.

Note that, as the motor <NUM>, another type of motor which can control rotational speed, such as an AC motor, a DC motor, or a brushless DC motor, may be used. The AC motor can change the rotational speed by changing an AC frequency. The DC motor can change the rotational speed by changing a motor voltage. The brushless DC motor can change the rotational speed by changing a pulse frequency.

The housing <NUM> is provided with a power button <NUM> for turning on or off a power source, and a plurality of light emitting units 54a and 54b.

The plurality of light emitting units 54a and 54b has a first light emitting unit 54a and a second light emitting unit 54b that emit different colors. The first light emitting unit 54a is a light emitting unit for indicating the operating state of the liquid medicine administration device <NUM>, and can emit light of different colors. The second light emitting unit 54b is a light emitting unit that lights or flashes to indicate the occurrence of an error. The first light emitting unit 54a and the second light emitting unit 54b are composed of, for example, LEDs.

Next, the action of the liquid medicine administration device <NUM> configured as described above will be described.

When in use, the liquid medicine administration device <NUM> is taken out of a cold storage and left at normal temperature for a certain period of time (for example, <NUM> minutes) to be brought back to room temperature. Next, the surface (tip end surface) of the sealing member <NUM>, which is a connection portion with the connector <NUM>, is wiped off with alcohol cotton, for example, to disinfect the connection portion. Then, the administration tool <NUM> is connected to the liquid medicine administration device <NUM>.

Next, the power button <NUM> is pressed. Then, the liquid medicine administration device <NUM> is mounted on the patient by attaching the device <NUM> to the skin S or clothes. Next, the puncture needle <NUM> punctures the skin S. Note that the liquid medicine administration device <NUM> may be attached to the patient before the puncture needle <NUM> punctures the skin S.

Next, delivery of liquid (administration of the liquid medicine M) is started. Specifically, the motor <NUM> is driven to transmit the rotational force from the pinion <NUM> to the feed screw <NUM> having the large gear 50b. As the feed screw <NUM> rotates, the nut member <NUM> engaged with the feed screw <NUM> advances, and the plunger <NUM> advances by being pushed by the nut member <NUM>. Thus, the liquid medicine M in the cylinder <NUM> is expelled. The liquid medicine M expelled from the inside of the cylinder <NUM> is administered (injected) into the patient's body via the administration tool <NUM> puncturing the patient.

When the delivery of liquid is completed due to the plunger <NUM> advancing to a predetermined position, a sound indicating that the delivery of liquid is completed is output from a speaker built in the liquid medicine administration device <NUM>, and the first light emitting unit 54a lights in a first color. When the delivery of liquid is completed, the puncture needle <NUM> is pulled out of the skin S (under the skin). Thereafter, the liquid medicine administration device <NUM> is thrown away.

Meanwhile, the advancing movement of the gasket <NUM> in the cylinder <NUM> has a first movement section (hereinafter referred to as an "initial sliding section") from when a part of the gasket <NUM> starts moving until the entire gasket <NUM> starts moving, a second movement section (hereinafter referred to as a "normal sliding section) following the first movement section.

The initial sliding section will be described with reference to <FIG> When the liquid medicine administration device <NUM> is stored for a long time, the sliding surface (two annular protrusions 34a in the illustrated example) of the gasket <NUM> adheres to the inner peripheral surface of the cylinder <NUM> as shown in <FIG> (on the left). As the plunger <NUM> advances, the gasket <NUM> starts to advance. Immediately after the gasket <NUM> starts to advance, only a part (the annular protrusion 34a on the proximal side) of the adhering portion is pulled off, whereby only a part of the gasket <NUM> advances, as shown in <FIG> (on the center). Then, when the entire adhering portion (the annular protrusions 34a on the distal side and the proximal side) is pulled off, the entire gasket <NUM> starts to advance (the gasket <NUM> transfer from the initial sliding section to the normal sliding section) as shown in <FIG> (on the right).

In the operation of the liquid medicine administration device <NUM> shown in <FIG>, the rotational speed of the motor <NUM> is controlled by the control unit <NUM>. Specifically, the control unit <NUM> has a program 28a set such that one cycle including one continuous rotation and one continuous stop of the motor <NUM> is repeated two or more times in the initial sliding section. The sliding resistance when the gasket <NUM> slides in the cylinder <NUM> is the highest in the initial sliding section.

The liquid medicine administration device <NUM> performs control to switch the rotational speed of the motor <NUM> (drive speed of the gasket <NUM>). Hereinafter, the operation of the liquid medicine administration device <NUM> including such speed switching will be described in more detail.

In <FIG>, when the power button <NUM> (<FIG>) of the liquid medicine administration device <NUM> is pressed and the power is turned on (step ST1), a process for checking a battery voltage is executed (step ST2). If it is determined that there is no abnormality in the battery voltage ("YES" in step ST2), a user is notified that there is no abnormality by lighting of the first light emitting unit 54a (or a buzzer sound output from the speaker), and counting of a predetermined time (for example, <NUM> minutes) is started (step ST3). Next, the liquid medicine administration device <NUM> is attached to the patient. When there is an abnormality in the battery voltage ("NO" in step ST2), an abnormality process is performed (step ST4). In the abnormality process, the second light emitting unit 54b lights or flashes to notify the user of an occurrence of abnormality. In the abnormality process, a buzzer sound may be output from the speaker.

When a predetermined time has elapsed after step ST3 ("YES" in step ST5), the control unit <NUM> of the liquid medicine administration device <NUM> drives the motor <NUM> to start administration at a first rotational speed S1 (initial sliding administration) (intermittent driving at low speed), starts counting of an administration time, and starts measurement of the initial sliding section (step ST6).

Next, the control unit <NUM> determines whether or not the initial sliding section has ended (whether the gasket <NUM> has moved a predetermined distance) (step ST7). In this case, the program 28a of the control unit <NUM> determines that the gasket <NUM> has passed the first movement section (determines that the initial sliding section has ended/the gasket <NUM> has moved a predetermined distance) based on, for example, the time in which the motor <NUM> operates at the first rotational speed S1. The stepping motor 40A used as the motor <NUM> rotates by a predetermined angle in one pulse, and a unit representing the number of pulses transmitted to the motor <NUM> in one second indicates a pulse frequency (pps). Therefore, the number of pulses transmitted to the stepping motor A40 is obtained by measuring the time in which the stepping motor 40A is operated at a predetermined pps, and the rotation amount can be determined by multiplying the number of pulses by a predetermined angle. When the stepping motor 40A is used as the motor <NUM>, the distance the gasket <NUM> moves can be calculated by multiplying the rotation amount of the motor <NUM> by the distance the gasket <NUM> advances in one rotation of the motor <NUM>. Therefore, whether or not the gasket <NUM> has moved a predetermined distance can be determined on the basis of the time during which the motor <NUM> operates at a predetermined speed (pps). When the stepping motor 40A is used as the motor <NUM>, the program 28a of the control unit <NUM> may determine whether or not the gasket <NUM> has moved a predetermined distance on the basis of the rotation amount (the number of transmitted pulses) of the motor <NUM> operating at the first rotational speed S1.

When the initial sliding section has ended ("YES" in step ST7), the control unit <NUM> of the liquid medicine administration device <NUM> switches from low-speed driving to administration (high-speed driving) at a second rotational speed S2 (step ST8). When the administration at high-speed driving is performed, and the control unit <NUM> determines that the administration is completed (the remaining amount of the liquid medicine is zero) ("YES" in step ST9), the administration is finished (step ST10). In this case, the first light emitting unit 54a is turned off (or a buzzer sound is output from the speaker) to notify the user of the completion of administration. If it is not determined that the administration has been completed ("NO" in step ST9) and it is determined that the administration time exceeds a time limit ("YES" in step ST11), the control unit <NUM> performs a process for detecting exceeding time limit (step ST12). In the process for detecting exceeding time limit, the second light emitting unit 54b lights or flashes to notify the user of an occurrence of abnormality. In the process for detecting exceeding time limit, a buzzer sound may be output from the speaker.

The initial sliding section is considerably shorter than the normal sliding section, and the length thereof is within a range of, for example, <NUM> to <NUM> or <NUM> to <NUM>. The normal sliding section indicates a section in which the gasket <NUM> moves after the gasket <NUM> moves beyond the initial sliding section until the advancing movement of the plunger <NUM> is stopped with the completion of delivery of the liquid medicine M, and the length of the normal sliding section is within a range of, for example, <NUM> to <NUM>.

<FIG> is a conceptual diagram (conceptual diagram of the operation of the liquid medicine administration device <NUM>) of the rotational speed of the motor <NUM> (a pulse signal transmitted to the motor <NUM> by the control unit <NUM>) for advancing the gasket <NUM> and the plunger <NUM>. The first rotational speed S1 of the motor <NUM> in the initial sliding section is within a range of, for example, <NUM> rpm to <NUM> rpm, preferably <NUM> rpm to <NUM> rpm. The second rotational speed S2 of the motor <NUM> in the normal sliding section is within a range of, for example, <NUM> rpm to <NUM> rpm, preferably <NUM> rpm to <NUM> rpm. The ratio of the first rotational speed S1 to the second rotational speed S2 is within a range of, for example, <NUM> to <NUM>%, preferably <NUM> to <NUM>%.

In the present embodiment, the control unit <NUM> controls the motor <NUM> such that the motor <NUM> repeatedly operates at the first rotational speed S1 and stops in the initial sliding section as shown in <FIG>. In other words, the control unit <NUM> controls the motor <NUM> such that one cycle including one continuous rotation and one continuous stop of the motor <NUM> is repeated two or more times in the initial sliding section.

The program 28a is set such that the advancing speed of the gasket <NUM> according to calculation in the initial sliding section is within a range of, for example, <NUM> to <NUM>/min. "The advancing speed of the gasket <NUM> according to calculation in the initial sliding section" means the average moving speed of the gasket <NUM> in the initial sliding section, that is, the speed calculated by dividing the distance of the initial sliding section by the time taken for the gasket <NUM> to move through the initial sliding section. The program 28a is set such that an estimated advancing distance of the gasket <NUM> calculated based on the rotation amount of the motor <NUM> in one cycle in the initial sliding section is within a range of, for example, <NUM> to <NUM>.

The control unit <NUM> also controls the motor <NUM> such that the motor <NUM> repeatedly operates and stops in the normal sliding section. In other words, the control unit <NUM> controls the motor <NUM> such that one cycle including one continuous rotation and one continuous stop of the motor <NUM> is repeated two or more times in the normal sliding section.

During the intermittent driving at low speed in which the motor <NUM> repeatedly operates and stops in the initial sliding section, each operation time T1a is within a range of, for example, <NUM> to <NUM> seconds, preferably <NUM> to <NUM> seconds. The duty ratio which is the ratio of the operation time T1a in one cycle including operation and stop during the intermittent driving at low speed is within a range of, for example, <NUM> to <NUM>%, preferably <NUM> to <NUM>%. Due to such intermittent driving at low speed, power consumption caused by the driving of the motor <NUM> can be effectively reduced, as compared with the case where the motor <NUM> is continuously driven. The program 28a is set such that, in one cycle during intermittent driving at low speed, the rotation of the motor <NUM> is stopped for a predetermined time when the number of pulses transmitted to the motor <NUM> reaches a predetermined value corresponding to the estimated advancing distance of the gasket <NUM> after the motor <NUM> starts rotating.

During intermittent driving at high speed in which the motor repeatedly operates and stops in the normal sliding section, each operation time T2a is within a range of, for example, <NUM> to <NUM> milliseconds, preferably <NUM> to <NUM> milliseconds, and each stop time T2b is <NUM> to <NUM> times the operation time T2a, preferably <NUM> to <NUM> times the operation time T2a. The duty ratio which is the ratio of the operation time T2a in one cycle including operation and stop during the intermittent driving is within a range of, for example, <NUM> to <NUM>%, preferably <NUM> to <NUM>%. Due to such intermittent driving, power consumption caused by the driving of the motor <NUM> can be effectively reduced, as compared with the case where the motor <NUM> is continuously driven.

The moving speed (the moving speed of the gasket <NUM> when the motor <NUM> rotates at the first rotational speed S1) when the gasket <NUM> advances in the initial sliding section is within a range of <NUM> to <NUM> per minute, preferably <NUM> to <NUM> per minute. The moving speed (the moving speed of the gasket <NUM> when the motor <NUM> rotates at the second rotational speed S2) when the gasket <NUM> advances in the normal sliding section is within a range of, for example, <NUM> to <NUM> per minute, although it depends on the administration time for administering the liquid medicine M.

In this case, the liquid medicine administration device <NUM> according to the first embodiment provides the following effects.

As has been described with reference to <FIG>, when the liquid medicine administration device <NUM> is stored for a long time, the sliding surface (two annular protrusions 34a in the illustrated example) of the gasket <NUM> adheres to the inner peripheral surface of the cylinder. Therefore, when, unlike the present invention, the gasket <NUM> is entirely advanced at once by continuously driving the motor <NUM>, the entire adhering portion needs to be simultaneously pulled off, which significantly increases the sliding resistance of the gasket <NUM>.

On the other hand, according to the liquid medicine administration device <NUM>, the gasket <NUM> is advanced at intervals in the initial sliding section of the gasket <NUM>, whereby, even if the sliding surface of the gasket <NUM> adheres to the inner peripheral surface of the cylinder <NUM>, the adhering portion is pulled off little by little. Thus, an excessive rise in sliding resistance in the initial sliding section can be suppressed. Accordingly, it is possible to prevent an increase in the driving force in the initial sliding section, and to provide the liquid medicine administration device <NUM> which is smaller in size than the conventional one.

The program 28a is set such that the stop time T1b in which the motor <NUM> is stopped is <NUM> to <NUM> times the operation time T1a in which the motor <NUM> is rotated in one cycle in the initial sliding section. Thus, since the stop time T1b of the motor <NUM> in one cycle in the initial sliding section is appropriately long, the adhering portion of the gasket <NUM> can be more reliably pulled off little by little, and an excessive rise in the sliding resistance in the initial sliding section can be further suppressed.

When the program 28a is set such that the stop time T1b in one cycle in the initial sliding section is within a range of <NUM> to <NUM> seconds, the stop time of the motor <NUM> in one cycle is appropriately long. Therefore, the adhering portion of the gasket <NUM> can be more reliably pulled off little by little, and an excessive rise in the sliding resistance in the initial sliding section can be further suppressed.

When the program 28a is set such that the advancing speed of the gasket <NUM> according to calculation in the initial sliding section is within a range of <NUM> to <NUM>/min, the driving force required to advance the gasket <NUM> in the initial sliding section can be sufficiently reduced.

When the program 28a is set such that the estimated advancing distance of the gasket <NUM> calculated based on the rotation amount of the motor <NUM> in one cycle is within a range of <NUM> to <NUM>, the driving force required to advance the gasket <NUM> in the first movement section can be sufficiently reduced.

The initial sliding resistance of the gasket <NUM> in the cylinder <NUM> differs depending on the moving speed of the gasket <NUM>, and the initial sliding resistance tends to increase as the moving speed of the gasket <NUM> is faster, while the sliding resistance afterward does not tend to depend on the moving speed of the gasket <NUM>. Therefore, in the initial sliding section, the sliding resistance is smaller as the moving speed of the gasket <NUM> is lower. On the other hand, in the normal sliding section, the sliding resistance does not tend to depend on the moving speed of the gasket <NUM>. The length of the initial sliding section with respect to the total advancing distance of the gasket <NUM> (the sum of the distance of the initial sliding section and the distance of the normal sliding section) during the operation of the liquid medicine administration device <NUM> is considerably small. That is, the initial sliding section is considerably shorter than the normal sliding section.

In view of this, the liquid medicine administration device <NUM> executes low-speed driving in which the gasket <NUM> is slowly moved by rotating the motor <NUM> at the first rotational speed S1 in the initial sliding section, and executes high-speed driving in which the gasket <NUM> is quickly moved by rotating the motor <NUM> at the second rotational speed S2 in the normal sliding section following the initial sliding section.

Therefore, the driving force required to advance the plunger <NUM> (required thrust) in the initial sliding section is suppressed, whereby a desired administration rate is achieved with an increase in power consumption being prevented. That is, when, unlike the present embodiment, the plunger <NUM> is driven at high speed in the initial sliding section as indicated by a broken line L2 in <FIG>, the sliding resistance of the gasket <NUM> with respect to the cylinder <NUM> considerably increases. In this case, if large power is supplied to the motor <NUM> in response to a large sliding resistance without changing the motor <NUM>, the power consumption increases. A high-cost motor or a large-sized motor is required to obtain required driving force without increasing power consumption.

On the other hand, when the plunger <NUM> is driven at low speed in the initial sliding section, the sliding resistance of the gasket <NUM> with respect to the cylinder <NUM> is considerably smaller than that of the gasket <NUM> driven at high speed in the initial sliding section, as indicated by a solid line L1 in <FIG>. Therefore, the liquid medicine administration device <NUM> can prevent an increase in power consumption and can administer the liquid medicine M at a desired administration rate without using a high-cost motor or a large-sized motor.

In the liquid medicine administration device <NUM>, it is preferable that the maximum value of the sliding resistance of the gasket <NUM> in the initial sliding section is <NUM> N or less by the motor <NUM> operating at the first rotational speed S1. Thus, the power consumption by the driving of the motor <NUM> can be reduced effectively.

Next, a liquid medicine administration device <NUM> according to a second embodiment shown in <FIG> will be described.

In the liquid medicine administration device <NUM>, a DC motor is used as a motor 40B that drives the advancing mechanism <NUM>. In the liquid medicine administration device <NUM>, a control unit <NUM> controls the operation of the motor 40B. The control unit <NUM> has a program 62a set such that one cycle including one continuous rotation and one continuous stop of the motor 40B is repeated two or more times in the initial sliding section.

The program 62a is set such that a time CT1 of one cycle in the initial sliding section is within a range of, for example, <NUM> to <NUM> seconds. The program 62a is set such that an operation time T1a in which the motor 40B is rotated in one cycle in the initial sliding section is within a range of, for example, <NUM> to <NUM> seconds. The motor 40B is a DC motor. Therefore, if the same voltage is applied to the motor 40B, the operation time T1a becomes longer as a load (torque load) applied to the motor 40B due to the sliding resistance of the gasket <NUM> is greater, and the operation time T1a becomes shorter as the load is smaller.

The program 62a is set such that, in one cycle in the initial sliding section, a stop time T1b in which the motor 40B is stopped is, for example, <NUM> to <NUM> times the operation time T1a in which the motor 40B is rotated. The program 62a is set such that the stop time T1b in one cycle in the initial sliding section is within a range of, for example, <NUM> to <NUM> seconds. The program 62a is set such that the advancing speed of the gasket <NUM> according to calculation in the initial sliding section is within a range of, for example, <NUM> to <NUM>/min. The program 62a is set such that the estimated advancing distance of the gasket <NUM> calculated based on the rotation amount of the motor 40B in one cycle in the initial sliding section is within a range of, for example, <NUM> to <NUM>. Note that the configuration in which the stop time T1b in one cycle in the initial sliding section is set to be <NUM> to <NUM> times the operation time T1a includes a configuration in which the stop time T1b is set to be <NUM> to <NUM> times the operation time T1a by the program 62a controlling the time of one cycle and the rotation amount of the motor 40B in the initial sliding section.

The liquid medicine administration device <NUM> includes a rotation amount detection sensor <NUM> (rotary encoder) that detects the rotation amount of the motor 40B. According to one aspect, the rotation amount detection sensor <NUM> is an optical transmissive encoder having a light emitting element and a light receiving element, and a pinion <NUM> functioning as a code wheel has a plurality of slits formed at intervals in the circumferential direction. A light transmission pattern is detected by the rotation amount detection sensor <NUM>. The rotational direction and the rotation amount of the motor 40B can be detected from the light transmission pattern. The program 62a is set such that, in one cycle in the initial sliding section, the rotation of the motor 40B is stopped for a predetermined time when the rotation amount of the motor 40B detected by the rotation amount detection sensor <NUM> after the motor 40B starts rotating reaches a predetermined value corresponding to the estimated advancing distance of the gasket <NUM>.

Next, the operation of the liquid medicine administration device <NUM> will be described. In the following, a first operation method (<FIG> and <FIG>) in which the control on the motor operation is not switched over the entire range of the initial sliding section and the normal sliding section and a second operation method (<FIG>) for switching the control on the motor operation with the transition from the initial sliding section to the normal sliding section will be described.

In the first operation method, when a power button <NUM> (<FIG>) of the liquid medicine administration device <NUM> is pressed and the power is turned on (step S101), a process for checking a battery voltage is executed (step S102), as shown in <FIG>. If it is determined that there is no abnormality in the battery voltage ("YES" in step S102), a user is notified that there is no abnormality, and counting of a predetermined time (for example, <NUM> minutes) is started (step S103). Next, the liquid medicine administration device <NUM> is attached to the patient. When there is an abnormality in the battery voltage ("NO" in step S102), an abnormality process is performed (step S104).

When a predetermined time has elapsed after step S103 ("YES" in step S105), the control unit <NUM> of the liquid medicine administration device <NUM> drives the motor 40B to start administration (start intermittent driving of the motor 40B), and starts counting of an administration time (step S106). In this case, the voltage applied to the motor 40B is the same in the initial sliding section and the normal sliding section. That is, the control unit <NUM> does not change the control on the motor 40B in the initial sliding section and the normal sliding section.

When the administration with intermittent driving is performed, and the control unit <NUM> determines that the administration is completed (the remaining amount of the liquid medicine is zero) ("YES" in step S107), the administration is finished (step S108). If it is not determined that the administration has been completed ("NO" in step S107) and it is determined that the administration time exceeds a time limit ("YES" in step S109), the control unit <NUM> performs a process for detecting exceeding time limit (step S110).

<FIG> is a conceptual diagram of the operation of the liquid medicine administration device <NUM> when the first operation method is performed. In <FIG>, the time CT1 of one cycle in the initial sliding section and a time CT2 of one cycle in the normal sliding section are set to be the same. An operation time T2a of the motor 40B in one cycle in the normal sliding section is set shorter than the operation time T1a of the motor 40B in one cycle in the initial sliding section.

Since the motor 40B is a DC motor, the rotational speed of the motor 40B changes depending on the load (torque load) applied to the motor 40B due to the sliding resistance of the gasket <NUM>. Therefore, the control unit <NUM> does not directly control the rotational speed of the motor 40B. On the other hand, when the gasket <NUM> transfers from the initial sliding section to the normal sliding section, the sliding resistance of the gasket <NUM> decreases, which leads to a decrease in load on the motor 40B. As a result, the rotational speed of the motor 40B naturally increases with the transition from the initial sliding section to the normal sliding section, although the voltage applied to the motor 40B is unchanged. In other words, the rotational speed of the motor 40B in the normal sliding section is higher than the rotational speed of the motor 40B in the initial sliding section.

Note that <FIG> shows as if the motor 40B rotates at the same rotational speed in all cycles in the initial sliding section, and the motor 40B also rotates at the same rotational speed in all cycles in the normal sliding section. However, since the rotational speed of the motor 40B varies depending on the load applied to the motor 40B as described above, the motor 40B does not necessarily rotate at the same rotational speed in the cycles in the initial sliding section in actuality. Similarly, the motor 40B does not necessarily rotate at the same rotational speed in the cycles in the normal sliding section in actuality.

Next, the second operation method of the liquid medicine administration device <NUM> will be described. In the second operation method, the control unit <NUM> switches control on the motor operation along with the transition from the initial sliding section to the normal sliding section. The flowchart showing the second operation method in <FIG> differs from the first operation method in that steps S206 to S208 are performed instead of step S106 in the flowchart showing the first operation method in <FIG>.

Steps S201 to S205 are the same as steps S101 to S105 of the first operation method, respectively. In the second operation method, when a predetermined time has elapsed after step S203 ("YES" in step S205), the control unit <NUM> drives the motor 40B to start administration (start intermittent driving of motor 40B), starts measurement of the initial sliding section, and starts counting of administration time (step S206).

Next, the control unit <NUM> determines whether or not the initial sliding section has ended (step S207). The distance the gasket <NUM> advances can be calculated by multiplying the rotation amount of the motor 40B detected by the rotation amount detection sensor <NUM> by the distance the gasket <NUM> advances in one rotation of the motor 40B. Therefore, the control unit <NUM> can determine whether or not the initial sliding section has ended on the basis of the rotation amount of the motor 40B obtained by the rotation amount detection sensor <NUM>.

When the initial sliding section has ended ("YES" in step S207), the control unit <NUM> of the liquid medicine administration device <NUM> switches control on the motor operation (transfers to high-speed driving) (step S208). The subsequent steps S209 to S212 are the same as steps S107 to S110 of the first operation method, respectively.

Some modes may be adopted as the process to be executed in step S208 (switching of control on motor operation), and the present specification shows a first mode (<FIG>), a second mode (<FIG>), and a third mode (<FIG>) below as examples.

As shown in <FIG>, in the first mode of switching of control on the motor operation, the motor 40B is continuously driven in the entire area of the normal sliding section. That is, the stop time of the motor 40B is not provided in the normal sliding section. In this case, the voltage applied to the motor 40B is the same between the initial sliding section and the normal sliding section. However, due to a decrease in sliding resistance in the normal sliding section, the rotational speed of the motor 40B increases. As described above, the motor 40B is continuously driven in the entire area of the normal sliding section, whereby the administration time can be shortened as compared with the first operation method.

Note that, in the first mode, the voltage applied to the motor 40B in the normal sliding section may be set higher than the voltage applied to the motor 40B in the initial sliding section. As the applied voltage is higher, the rotational speed of the motor 40B increases more. Therefore, when the voltage applied to the motor 40B is increased, the rotational speed of the motor 40B in the normal sliding section further increases as shown by a phantom line. This can further reduce the administration time.

As shown in <FIG>, in the second mode of switching of control on motor operation, the operation time T2a of the motor 40B in one cycle in the normal sliding section is equal to the operation time T1a of the motor 40B in one cycle in the initial sliding section, and the motor 40B is intermittently driven in the normal sliding section. However, the time CT2 of one cycle in the normal sliding section is set shorter than the time CT1 of one cycle in the initial sliding section. Thus, the administration time can be shortened as compared with the first operation method. The time CT2 of one cycle in the normal sliding section is, for example, <NUM> to <NUM> times the time CT1 of one cycle in the initial sliding section. Note that the voltage applied to the motor 40B in the normal sliding section may be set higher than the voltage applied to the motor 40B in the initial sliding section.

As shown in <FIG>, in the third mode of switching of control on motor operation, the time CT1 of one cycle in the initial sliding section is equal to the time CT2 of one cycle in the normal sliding section, and the motor 40B is intermittently driven in the normal sliding section. However, the operation time T2a of the motor 40B in one cycle in the normal sliding section is set longer than the operation time T1a of the motor 40B in one cycle in the initial sliding section. Thus, the administration time can be shortened as compared with the first operation method. The operation time T2a of the motor 40B in one cycle in the normal sliding section is, for example, <NUM> to <NUM> times the operation time T1a of the motor 40B in one cycle in the initial sliding section. Note that the time CT2 of one cycle in the normal sliding section may be set shorter than the time CT1 of one cycle in the initial sliding section. The voltage applied to the motor 40B in the normal sliding section may be set higher than the voltage applied to the motor 40B in the initial sliding section.

According to the liquid medicine administration device <NUM> configured as described above, the gasket <NUM> is advanced at intervals in the initial sliding section of the gasket <NUM>, whereby, even if the sliding surface of the gasket <NUM> adheres to the inner peripheral surface of the cylinder <NUM>, the adhering portion is pulled off little by little, as with the above-mentioned liquid medicine administration device <NUM>. Thus, an excessive rise in sliding resistance in the initial sliding section can be suppressed. Accordingly, it is possible to prevent an increase in the driving force in the initial sliding section, and to provide the liquid medicine administration device <NUM> which is smaller in size than the conventional one.

Claim 1:
A liquid medicine administration device (<NUM>, <NUM>) for administering a liquid medicine (M) into a living body, the device comprising:
a cylinder (<NUM>) filled with the liquid medicine (M);
a gasket (<NUM>) located inside the cylinder (<NUM>) in a slidable manner;
a liquid lubricant (LM) applied to an inner peripheral surface of the cylinder (<NUM>) or an outer peripheral surface of the gasket (<NUM>);
an advancing mechanism (<NUM>) configured to advance the gasket (<NUM>) in a distal direction;
a drive mechanism (<NUM>) including a motor (<NUM>, 40B) that is configured to drive the advancing mechanism (<NUM>);
a battery (<NUM>) configured to supply power to the motor (<NUM>, 40B); and
a control unit (<NUM>, <NUM>) configured to control an operation of the motor (<NUM>, 40B),
characterized in that an advancing movement of the gasket (<NUM>) within the cylinder (<NUM>) includes a first movement section from when a part of the gasket (<NUM>) starts moving until the gasket (<NUM>) entirely starts moving, and a second movement section following the first movement section, and
the control unit (<NUM>, <NUM>) includes a program (28a, 62a) set such that one cycle including one continuous rotation and one continuous stop of the motor (<NUM>, 40B) is repeated two or more times in the first movement section.