Multi-step type needleless syringe or needleless injection system, and driving method and control program thereof

Abstract

[PROBLEM] An objective of the present invention is to develop a multi-step type needleless syringe in which an injection liquid in a single ampule can be repeatedly injected over multiple steps. [SOLUTION] The present invention provides a needleless syringe or a needleless injection system in which an elastic body energy storage unit for storing energy in an elastic body for pressing a piston and a piston head stop position adjustment unit for adjusting the stop position of a piston head are each driven by actuators, and the actuators thereof can be controlled by a control unit to repeatedly A) store energy in the elastic body by means of the elastic body storage unit, B) change the stop position of the piston head in the forward direction by means of the piston head stop position adjustment unit, and C) drive the piston in the forward direction by releasing the energy in the elastic body, and thereby gradually press using the piston head and advance a plunger for pushing out an injection liquid in the ampule, and repeatedly inject the injection liquid in a single ampule over multiple steps.

Description

Multi-step needle-free syringe or needle-free injection system, and their driving method and control program

[0001] The present invention relates to a needle-free syringe or needle-free injection system that can inject an injection solution into the subcutaneous or intracutaneous cavity without using a needle by ejecting the injection solution at high speed using the force of an elastic body such as a spring, and provides a multi-step needle-free syringe or needle-free injection system that can repeatedly eject the injection solution from a single ampule in multiple divided doses. The present invention also provides a drive method and control program for a needle-free syringe or needle-free injection system that can repeatedly eject the injection solution from a single ampule in multiple divided doses.

[0002] A needle-free syringe is a medical device that can inject an injection solution into or under the skin without using a needle by ejecting the injection solution at high speed from a nozzle with a minute diameter. Because needle-free syringes do not pierce the skin with a needle, they have the advantage of causing less pain than syringes that use needles, and also of preventing infections such as viruses and injuries caused by needlestick injuries.

[0003] These advantages of needle-free syringes are particularly beneficial in medical care for children who are afraid of needle injections and patients with acrophobia (apophobia). Following the needle-free syringe developed by the applicant receiving approval for the manufacture and sale of the first medical device in Japan, sales of the needle-free syringe Injex50 began in 2020, and at the time of filing this application, its use is expanding, particularly in pediatric dentistry.

[0004] The driving principle of needle-free syringes is typically based on the elastic force of a spring or other similar device. Other methods include those based on gas pressure, electromagnetic force, and explosives. However, gas pressure and electromagnetic force systems have difficulty injecting injection fluid at high speeds. Therefore, while small amounts of injection fluid can be injected into the skin (epidermis and dermis), they are unable to inject subcutaneously (tissues deeper than the dermis). Explosives also pose problems with controlling explosive force and safety. On the other hand, systems based on the elastic force of a spring or other similar device apply stress to an elastic body such as a spring to continuously deform it, storing elastic energy (energy storage of the elastic body), and then release the deformed body to suddenly release the stored elastic energy (energy release of the elastic body). This allows injection fluid to be ejected at high speeds, and the elastic energy used for ejection is constant. Due to these characteristics, systems based on the elastic force of a spring or other similar device are ideal for needle-free syringes, as they can reliably and safely inject even small amounts of injection fluid subcutaneously.

[0005] The driving principle of a conventional needle-free syringe that utilizes the elastic force of a spring or the like is explained below using the diagrams in Patent Document 1, previously filed by one of the inventors of the present application. Figure 8 is a drawing of Figures 23 and 24 of Patent Document 1, with new reference numerals added in accordance with the reference numerals used in the present application. Figure 8(A) shows the conventional needle-free syringe with the spring compressed and charged, and Figure 8(B) shows the compressed spring released and the injection liquid ejected. As shown in Figure 8(A), an ampoule 3A can be attached to the front of the needle-free syringe 1A. The ampoule 3A has a cylinder-like structure and contains the injection liquid therein. The injection liquid can be ejected by pushing the plunger 304A into the cylinder-like structure. A piston 5A that can slide back and forth is housed inside the body of the needle-free syringe 1A, and a piston head 522A is provided at the front end of the piston 5A. Furthermore, a spring 6A is installed inside the needle-free syringe 1A, applying a forward force to the piston 5A. By manually moving the piston 5A backward, the spring 6A is compressed, as shown in FIG. 8A. Here, a trigger finger 1211A prevents the piston 5A from moving forward, maintaining the spring 6A in a compressed, "energized" state. The trigger finger 1211A is provided at the front end of the trigger 1210A, and a push end 1212A provided at the rear end of the trigger 1210A is raised by the force of another spring, which pushes down the trigger finger 1211A using the principle of leverage, preventing the piston 5A from moving forward. To maintain the raised state of the push end 1212A, a safety lock 1220A, which can be moved back and forth, is pressed under the push end 1212A to lock it.8(B), the safety lock 1220A is moved backward to release the lock, and the push end 1212A is pushed downward to lift the trigger finger 1211A using the principle of leverage, allowing the force of the spring 6A to freely drive the piston 5A forward. By releasing the spring 6A in this way and driving the piston 5A forward at high speed, the piston head 522A presses the plunger 304A, and the injection liquid in the ampoule 3A can be injected at high speed from the minute-diameter discharge port 303A.

[0006] In the fields of skin disease treatment and cosmetic and hair growth medicine, medicinal liquids are sometimes injected into multiple locations on the skin. However, if a multi-step needle-free injector that injects the liquid in a single ampoule in multiple doses were developed, more efficient treatment would become possible in these medical fields as well.

[0007] Needle-free syringes that utilize the elastic force of a spring or the like inject a liquid by storing and releasing the energy of an elastic body such as a spring, have traditionally been considered by those skilled in the art to be unable to perform continuous injections within a predetermined time and also unable to set the amount of injection per injection (paragraphs

[0010] and

[00011] of Patent Document 2). Therefore, the inventors of Patent Document 2 have succeeded in developing a needle-free injection system that utilizes gas pressure, allowing the number of continuous injections, the time interval between continuous injections, the amount of injection per injection, etc. to be set (paragraph

[0001] of Patent Document 2).

[0008] However, as mentioned above, a system utilizing the elastic force of a spring or the like is most suitable for a needle-free syringe, and therefore attempts have been made to develop multi-step needle-free syringes utilizing the elastic force of a spring or the like (Patent Documents 3 to 5). Patent Document 3 discloses a needle-free syringe that can eject an injection in several divided injections by gradually releasing a charged spring in multiple steps, thereby pressing the plunger in multiple steps. Patent Documents 4 and 5 disclose needle-free syringes that can eject multiple injections by transmitting the driving force of the piston by the force of the released spring to the plunger via a cylindrical stepped barrel (revolver) having multiple spiral staircase-like steps. Specifically, the lowest step of the stepped barrel (revolver) is initially in contact with the plunger, and the pushing force of the piston, driven by the charging and releasing of the spring, is transmitted to the plunger via the stepped barrel (revolver), causing the plunger to move forward and perform the first injection. Next, the stepped barrel (revolver) is rotated so that the next step, which is located further forward, comes into contact with the plunger, and then the pressure of the piston, which is driven by the spring again charging and releasing, is transmitted to the plunger through the stepped barrel (revolver), causing the plunger to move further forward and perform a second injection. By repeating this operation, multiple injections can be performed.

[0009] International Publication No. WO2014 / 042930 Japanese Patent Application Laid-Open No. 2015-036108 Japanese Patent Application Laid-Open No. 2012-055641 Japanese Patent Application Laid-Open No. 2022-527712 Japanese Patent Application Laid-Open No. 2020-179038

[0010] As mentioned above, among needle-free syringes that utilize the elastic force of a spring or the like, attempts have been made to develop multi-step needle-free syringes that inject the injection liquid from a single ampule in multiple increments (Patent Documents 3 to 5). However, the needle-free syringe described in Patent Document 3 injects the injection liquid by gradually releasing a charged spring in multiple increments. Therefore, although the spring is sufficiently compressed and has a large elastic stress at the first release, repeated stepwise releases cause the spring to stretch and the elastic stress to decrease, resulting in a weakened injection force and an inability to obtain a constant injection force. Furthermore, the needle-free syringes described in Patent Documents 4 and 5 utilize a cylindrical stepped barrel (revolver) with multiple spiral staircase-like steps, enabling multiple injections by rotating the stepped barrel (revolver) to change the position of the step that contacts the plunger. However, since the amount of injection per shot is determined by the step of the stepped barrel (revolver), the amount of injection per shot and the injection pressure are physically fixed, and there is a problem that the amount of injection of the injection liquid and the injection pressure cannot be adjusted. Furthermore, the needleless syringes described in Patent Documents 4 and 5 require manual simultaneous compression of the spring and rotation of the stepped barrel (revolver), which necessitates weakening the force of the spring, making it difficult to deliver the medicinal liquid under the skin.

[0011] Therefore, an object of the present invention is to develop a multi-step needleless syringe with a new drive mechanism that can repeatedly inject the injection liquid in a single ampule in multiple doses, maintain a constant injection force even when repeatedly injected, adjust the injection volume and injection pressure of the injection liquid, and automatically perform continuous injection without manual operation.

[0012] In order to solve this problem, the inventors conducted extensive research and found that by using a piston connected to a piston base so that the relative forward and backward position of a piston rod equipped with a piston head with respect to the piston base can be changed, it is possible to arbitrarily adjust the stop position of the piston head that presses the plunger forward or backward. The inventors also found that by driving a piston head stop position adjustment unit that adjusts the stop position of the piston head and an elastic body energy storage unit that stores energy in the elastic body that presses the piston with actuators and controlling these actuators with a control unit, repeating the following: (a) energy storage of the elastic body by the elastic body energy storage unit, (b) forward position change of the piston head stop position adjustment unit with respect to the piston head, and (c) forward drive of the piston by deenergizing the elastic body, the plunger that pushes out the injection liquid in the ampule is advanced by the piston head in stages, and the injection liquid in a single ampule can be repeatedly injected in multiple divided doses. Furthermore, the inventors discovered that the elastic body can be charged each time an injection is made, resulting in a constant injection force, that the injection amount and injection pressure can be adjusted by adjusting the distance by which the piston head stopping position is changed, and that automatic continuous injection is possible because an actuator is used instead of manual operation, leading to the completion of the present invention. That is, the present invention provides the following invention [1]: a needle-free syringe or needle-free injection system.[1] A needle-free syringe or needle-free injection system comprising: a housing main body to the front of which an ampoule having a plunger for pushing out an injection liquid therein; a piston provided on the housing main body so as to be slidable back and forth; and an elastic body that applies a forward force to the piston, wherein the piston head of the piston can press the plunger by releasing the stored elastic body and driving the piston forward to inject the injection liquid in the ampoule, the needle-free syringe or needle-free injection system comprising: an elastic body storage unit that stores energy in the elastic body by moving the piston backward; a first actuator that drives the elastic body storage unit; a piston head stop position adjustment unit that adjusts the piston head stop position where the piston head stops when the stored elastic body is released and the piston is driven forward; a second actuator that drives the piston head stop position adjustment unit; and a control unit that controls the first actuator and the second actuator, wherein the piston has a piston base to which a forward force is applied by the elastic body, and a piston rod equipped with the piston head, the piston rod is connected to the piston base so that it can receive a forward force from the piston base and can change its position forward or backward relative to the piston base; the piston head stop position adjustment unit can adjust the piston head stop position by changing the position of the piston rod forward or backward relative to the piston base using the driving force of the second actuator; and the control unit controls the driving of the first actuator and the second actuator to repeatedly charge the elastic body by the elastic body charge unit, change the position of the piston head stop position forward by the piston head stop position adjustment unit, and drive the piston forward by releasing the elastic body.

[0013] The needle-free syringe or needle-free injection system of the present invention has a piston head stop position adjustment unit that can adjust the stop position of the piston head, so that the number of injections per ampoule or the amount of injection liquid per injection can be changed or set by adjusting the distance by which the piston head stop position is moved forward.The inventors have discovered that the needle-free syringe or needle-free injection system is equipped with an interface that sets the number of injections per ampoule or the amount of injection liquid per injection, and that by controlling the actuator that drives the piston head stop position adjustment unit in accordance with the user's settings via the interface, the user can change or set the number of injections per ampoule or the amount of injection liquid per injection.That is, the present invention provides the following needle-free syringe or needle-free injection system [2]. [2] The needle-free syringe or needle-free injection system according to [1] above, further comprising an interface for setting the number of injections per ampoule or the amount of injection liquid per injection, wherein the control unit controls the distance by which the piston head stop position is moved forward by controlling the drive amount of the second actuator in accordance with the number of injections per ampoule or the amount of injection liquid per injection set by a user via the interface.

[0014] The needle-free syringe or needle-free injection system of the present invention is characterized by using a piston rod connected to the piston base so that it can receive a forward force from the piston base and can change its forward / backward position relative to the piston base. The connection structure between the piston rod and the piston base is not particularly limited and can take various structures, as will be described later, but a structure connected by a male and female thread is the simplest and can be manufactured easily. That is, the present invention provides the following needle-free syringe or needle-free injection system invention [3]. [3] The needle-free syringe or needle-free injection system according to [1] or [2], characterized in that the piston rod and the piston base are connected to each other by a male and female thread structure, and the piston head stop position adjustment unit changes the position of the piston rod forward / backward relative to the piston base by rotating the piston rod and the piston base relatively using the driving force of the second actuator.

[0015] When the connecting structure of [3] above is adopted, it is necessary to rotate the piston rod and the piston base relatively by the driving force of the actuator, but when rotating the piston rod, it is preferable that the structure of the piston rod and the piston head stop position adjustment unit be as shown in the following [4]. That is, the present invention provides a needle-free syringe or needle-free injection system according to the invention of the following [4]. [4] The needle-free syringe or needle-free injection system according to [3] above, characterized in that a spur gear having a plurality of teeth with a linear ridge extending in the front-rear direction is formed on the outer periphery of a part of the piston rod, and the piston head stop position adjustment unit has a cylindrical internal gear that is slidable back and forth relative to the spur gear and has a plurality of teeth with a linear ridge extending in the front-rear direction on its inner periphery, thereby allowing the rotational driving force of the second actuator to be transmitted to the spur gear via the internal gear to rotate the piston rod regardless of the position of the piston rod sliding back and forth.

[0016] The elastic body energy storage unit of the needle-free syringe or needle-free injection system of the present invention is not particularly limited and can take various mechanisms, as will be described later, but a cam mechanism such as the one described in the following item [5] is preferred because it can easily convert the rotational driving force of the actuator into a driving force in the front-rear direction of the piston. That is, the present invention provides the following needle-free syringe or needle-free injection system of the invention [5]. [5] The needle-free syringe or needle-free injection system according to any of items [1] to [4] above, characterized in that the elastic body energy storage unit has a cam that can convert the rotational motion of the first actuator into a front-rear direction motion of the piston, the cam is provided to be rotatable around an axis in the front-rear direction along which the piston slides, and the cam has a shape such that the front-rear direction thickness of the portion of the cam that abuts the piston changes with rotation of the cam, thereby converting the rotational motion of the first actuator into a front-rear direction motion of the piston to store energy in the elastic body.

[0017] When the cam mechanism of [5] above is employed, it is preferable to further shape the cam as in the following [6], since this allows the elastic body to be continuously charged and released. That is, the present invention provides a needle-free syringe or needle-free injection system according to the following [6]. [6] The needle-free syringe or needle-free injection system according to [5] above, characterized in that the cam has a portion in which the thickness in the front-to-rear direction of the portion that abuts against the piston gradually increases as the cam rotates, thereby enabling the elastic body to be charged, and a portion in which the thickness of the portion that abuts against the piston has a stepped shape that suddenly decreases as the cam rotates, thereby enabling the elastic body to be released.

[0018] The needle-free syringe or needle-free injection system of the present invention further comprises a sensor that detects the position of the piston rod in the forward / backward direction and a sensor that detects the position of the piston base in the forward / backward direction, thereby making it possible to prevent excessive force from being applied to components such as the piston, elastic body, and ampoule, and to more accurately control the position of the piston head. That is, the present invention provides the following needle-free syringe or needle-free injection system invention [7]. [7] The needle-free syringe or needle-free injection system according to any of [1] to [6] above, further comprising: a piston rod position sensor that can detect the position of the piston rod in the forward / backward direction and transmit the detection result to a control unit; or a piston base position sensor that can detect the position of the piston base in the forward / backward direction and transmit the detection result to a control unit.

[0019] A needle-free syringe has difficulty penetrating loose skin when injecting an injection solution, but easily penetrates and injects subcutaneously when injecting tight skin. Therefore, it is preferable to attach an attachment to the front end of the needle-free syringe, press the attachment against the skin to taut it, and then inject the injection solution into the skin. However, pressing the attachment against the skin causes pressure pain, which is particularly problematic when performing needle-free injections on facial skin for cosmetic medical purposes. Even molding the attachment out of a flexible material did not solve this problem. Therefore, the inventors developed a vacuum attachment that can taut the skin by adsorbing it to the attachment using negative pressure generated by suction, without forcing it against the attachment. That is, the present invention provides the following invention [8]: a needle-free syringe or needle-free injection system. [8] The needle-free syringe or needle-free injection system according to any one of [1] to [7] above, further comprising: a vacuum attachment having a cylindrical shape with two open ends, one open end of which can be attached to the plunger or the front part of the machine case main body to which the plunger is attached, and the other open end of which can be brought into contact with the skin; and an aspirator that can bring the skin into close contact with the attachment by sucking air from within the vacuum attachment.

[0020] The present invention also provides the following inventions [9] and

[10] , which are methods for driving a needle-free syringe or a needle-free injection system. [9] A method for driving a needle-free syringe or a needle-free injection system, which has a housing main body to the front of which an ampoule having a plunger for pushing out an injection liquid therein can be attached, a piston provided on the housing main body so as to be slidable back and forth, and an elastic body that applies a forward force to the piston, and which is capable of pressing the plunger with a piston head of the piston by releasing the stored elastic body and driving the piston forward, thereby injecting the injection liquid in the ampoule, comprising: A) a step of storing the elastic body using an elastic body storing unit that stores the elastic body by moving the piston backward, and a first actuator that drives the elastic body storing unit; B) a step of changing the piston head stop position to a position in the forward direction using a piston head stop position adjusting unit that adjusts a piston head stop position at which the piston head stops when the stored elastic body is released and the piston is driven forward, and a second actuator that drives the piston head stop position adjusting unit; C) driving the piston forward by releasing the elastic body, thereby pressing the plunger with the piston head of the piston, and injecting the injection liquid in the ampoule.

[0021]

[10] The driving method for the needle-free syringe or needle-free injection system according to [9] above, characterized in that in step B), the distance by which the piston head stop position is moved forward is controlled by controlling the drive amount of the second actuator according to the number of injections of the injection solution or the amount of injection solution per injection set by the user.

[0022] In the method for driving the needle-free syringe or needle-free injection system of the present invention, if the step of A) storing energy in the elastic body and the step of B) changing the piston head stop position to a forward position are carried out simultaneously, the operating time for injecting the injection liquid can be shortened, and this is a preferable driving method. That is, the present invention provides the following invention

[11] , a method for driving a needle-free syringe or needle-free injection system.

[11] The method for driving the needle-free syringe or needle-free injection system described in [9] or

[10] above, characterized in that step A) and step B) are carried out simultaneously.

[0023] In the method for driving a needle-free syringe or needle-free injection system of the present invention, a sensor is used to detect the position of the piston rod, and when it is detected that the piston rod has moved forward beyond a predetermined position, driving of the second actuator is stopped, thereby preventing excessive force from being applied to components such as the piston and ampoule, and making it possible to more accurately control the position of the piston head. Furthermore, when A) the step of storing energy in the elastic body and B) the step of changing the piston head stop position to a forward position are performed simultaneously, if the piston rod advances faster than the speed at which the piston base retreats, the piston head will press against the plunger, causing leakage of the injection liquid. However, by stopping the actuator based on the sensor that detects the position of the piston rod, such leakage can be prevented. That is, the present invention provides the following invention

[11] : a method for driving a needle-free syringe or needle-free injection system.

[12] The method for driving a needle-free syringe or a needle-free injection system according to any one of [9] to

[11] above, wherein in step B), a piston rod position sensor is used to detect the position of the piston rod in the forward / backward direction, and when it is detected that the position of the piston rod has moved forward beyond a predetermined position, driving of the second actuator is stopped.

[0024] In the method for driving a needle-free syringe or needle-free injection system of the present invention, if the steps of A) energizing the elastic body, B) changing the piston head stop position to a forward position, and C) deenergizing the elastic body to inject the injection liquid are performed consecutively in a short period of time immediately before the injection liquid is injected, there is no need to maintain the elastic body in an energized state for a long period of time, and this is a preferable driving method because it is possible to prevent accidental injection of the injection liquid when the user does not intend. That is, the present invention provides the following invention

[13] : A method for driving a needle-free syringe or needle-free injection system.

[13] A method for driving a needle-free syringe or needle-free injection system according to any of [9] to

[12] above, characterized in that steps A) to C) are performed immediately before the injection liquid is injected.

[0025] The present invention further provides a control program for a needle-free syringe or a needle-free injection system according to the following

[14] to

[17] .

[14] A control program that causes a control unit of the needle-free syringe or needle-free injection system according to [1] above to execute information processing including: A') generating a command signal to drive the first actuator by a predetermined amount in order to energize the elastic body, B') generating a command signal to drive the second actuator by a predetermined amount in order to change the piston head stop position to a position in the forward direction, and C') generating a command signal to release the energy of the elastic body in order to release the elastic body.

[0026]

[15] The control program according to

[14] , further comprising causing the control unit to execute information processing to determine a predetermined amount for driving the second actuator in step B') based on the number of injections of the injection solution or the amount of injection solution per injection set by a user.

[0027]

[16] The control program according to

[14] or

[15] , characterized in that the control unit simultaneously executes the signal generation of step A') and the signal generation of step B').

[0028]

[17] The control program according to any one of

[14] to

[16] , characterized in that immediately after receiving a signal instructing an injection from a user through an interface, the control unit executes the information processing of A') to C').

[0029] The needle-free syringe or needle-free injection system, and drive method and control program for the needle-free syringe or needle-free injection system of the present invention drive, by an actuator, an elastic body energy storage unit that stores energy in the elastic body, and also drive, by an actuator, a piston head stop position adjustment unit that adjusts the stop position of the piston head, and the drive of these actuators is controlled by a control unit, so that the elastic body is charged by the elastic body energy storage unit, the piston head stop position adjustment unit changes the piston head stop position forward, and the piston is driven forward by releasing the energy of the elastic body repeatedly. This has the effect of gradually pressing and advancing the plunger that pushes out the injection liquid in the ampule, and making it possible to repeatedly inject the injection liquid in a single ampule in multiple doses.

[0030] FIG. 1 is a schematic diagram showing the internal structure of a needle-free syringe according to a first embodiment of the present invention. It is a cross-sectional view of the needle-free syringe according to the first embodiment shown in FIG. 1. FIG. 2(A) shows a cross-sectional view taken along a plane including dashed line C1-C2 in FIG. 1, and FIG. 2(B) shows a cross-sectional view taken along a plane including dashed line C3-C4 in FIG. 1. It is a schematic diagram showing the state in which the cam and piston follower are in contact with each other in the needle-free syringe according to the first embodiment, and the change in the thickness of the cam. FIG. 3(A) is a schematic diagram showing the state in which the cam and piston follower are in contact with each other, as viewed from the rear along the axis along which the piston slides in FIG. 1. FIG. 3(B) is a graph showing the change in the thickness of the cam at the point where the cam and piston follower are in contact with each other when the gearwheel rotates. It is a schematic diagram showing the operation of the internal structure of the needle-free syringe according to the first embodiment when the piston head stop position is changed and the elastic body is released. FIG. 4(A) shows the state in which the piston head has moved forward from the state shown in FIG. 1. Fig. 4(B) shows a state in which the piston has stopped after being driven forward by releasing the elastic body (coil spring) from the state of Fig. 4(A). Fig. 4(B) is a flowchart showing information processing executed by an information processing device by an injection control program, which is part of the control program for the needle-free syringe of the first embodiment. Fig. 4(B) is a schematic diagram showing a needle-free injection system of a second embodiment of the present invention. Fig. 7 is a schematic diagram showing the cross-sectional structure of the front end of a multi-step injector equipped with a vacuum attachment and how to use it. Fig. 7(A) shows the state before the skin is adsorbed to the vacuum attachment, and Fig. 7(B) shows the state after the skin is adsorbed to the vacuum attachment. Fig. 4(B) is a diagram explaining the driving principle of a conventional needle-free syringe that utilizes the elastic force of a spring or the like.

[0031] 1. Needle-Free Syringe or Needle-Free Injection System 1-1. Overview of the Needle-Free Syringe or Needle-Free Injection System The needle-free syringe or needle-free injection system of the present invention is a needle-free syringe that utilizes the elastic force of an elastic body such as a spring. It uses a piston that is slidable back and forth and an elastic body that applies a forward force to the piston. By releasing the stored elastic body, the piston is driven forward, causing the piston head to press the plunger of the ampoule and inject the injection liquid in the ampoule at high speed. In the present invention, an "elastic body" refers to a member that deforms when stress is applied and returns to its original shape when the stress is released. "Elastic body" includes, but is not limited to, coil springs, leaf springs, compression springs, tension springs, rubber, and the like. In the present invention, "energy storage" refers to applying stress to an elastic body to continuously deform it and store elastic energy in the elastic body, and "energy release" refers to converting the stored elastic energy into kinetic energy by releasing the stress and returning the deformed elastic body to its original shape.

[0032] The ampoule used in the needle-free syringe or needle-free injection system of the present invention can be attached to the front of the needle-free syringe housing. An ampoule typically has a cylinder containing an injection solution, a small-diameter nozzle at the front end of the cylinder, and a plunger that can be inserted into the cylinder to expel the injection solution. Because injection solutions to be injected into the body must be sterile, ampoules are used by filling a sterile injection solution into a sterilized ampule, or ampoules pre-filled with an injection solution are purchased and used. Once the injection solution has been completely dispensed, the used ampule is usually disposable. Repeated injections can be performed by removing the ampule attached to the front of the needle-free syringe housing and replacing it with a new ampule. In this way, the ampule can be a separate component from the needle-free syringe of the present invention, and the needle-free syringe of the present invention may be sold with the ampule removed. Furthermore, the ampoule may be reused repeatedly. For example, by providing an injection port for injecting an injection solution into the ampoule and attaching an injection solution injector to the needleless syringe of the present invention, the injection solution in the ampoule can be repeatedly ejected and injected, allowing the ampoule to be used continuously without replacing it.

[0033] The needle-free syringe or needle-free injection system of the present invention is characterized by including a housing main body to which an ampoule can be attached at its front portion, a piston slidably mounted on the housing main body back and forth, an elastic body that applies a forward force to the piston, an elastic body energy storage unit that stores energy in the elastic body by moving the piston backward, a first actuator that drives the elastic body energy storage unit, a piston head stop position adjustment unit that adjusts the position at which the piston head stops when the stored elastic body is released to drive the piston forward, a second actuator that drives the piston head stop position adjustment unit, and a control unit that controls the first actuator and the second actuator. The needle-free syringe or needle-free injection system of the present invention may further include configurations other than those described above. In the present invention, the above configurations may be divided into multiple devices, in which case the system will be a needle-free injection system. For example, but not limited to, the control unit may be a control device separate from the needle-free syringe main body, and the needle-free syringe main body and the control device may be connected via wired or wireless communication to form a needle-free injection system.

[0034] The "elastic body energy storage unit" included in the needle-free syringe or needle-free injection system of the present invention is not particularly limited, and any mechanism may be used as long as it is capable of moving the piston backward using the driving force of the actuator. Because the elastic body applies a forward force to the piston, moving the piston backward causes the elastic body to deform (compress or expand in the case of a coil spring), thereby storing elastic energy. In the present invention, "forward direction" refers to the direction in which the piston presses the plunger of the ampule on the axis along which the piston slides back and forth. Furthermore, "rearward" refers to the direction opposite to "forward direction." Examples of mechanisms that can move the piston backward using the driving force of the actuator include, but are not limited to, a cam mechanism, a ball screw mechanism, a timing belt mechanism, a rack and pinion mechanism, and the like.

[0035] The "elastic body charging unit" included in the needle-free syringe or needle-free injection system of the present invention can be given the function of releasing the force that moves the piston backward, thereby releasing the elastic body. Alternatively, a mechanism separate from the "elastic body charging unit" can be used to hold the piston in position after it has moved backward and then release the force to release the elastic body. Examples of such mechanisms include, but are not limited to, a trigger or safety lock mechanism such as those disclosed in Patent Document 1. However, if the piston is held backward by a trigger or safety lock mechanism, there is a risk of the trigger being accidentally activated, causing the injection solution to be ejected and resulting in injury to the human body. Therefore, in the needle-free syringe or needle-free injection system of the present invention, it is preferable that, immediately after the user performs the injection operation, the elastic body charging unit moves the piston backward and then releases the force to release the piston, successively within a short period of time.

[0036] The "piston head stop position adjustment unit" provided in the needle-free syringe or needle-free injection system of the present invention is a mechanism that adjusts the position at which the piston head stops when the stored elastic body is released to drive the piston forward (referred to as the "piston head stop position" in the present invention). When the piston head presses the plunger to inject the injection liquid from the ampule, the plunger is pushed to the position at which the piston head stops, thereby injecting the injection liquid. Therefore, by adjusting the piston head stop position, it is possible to adjust the amount of injection liquid to be injected. The adjustment of the piston head stop position is made possible by using a piston with the following mechanism. The piston used in the needle-free syringe or needle-free injection system of the present invention has a piston base to which a forward force is applied by the elastic body, and a piston rod equipped with a piston head. Here, the piston rod is connected so as to be able to receive a forward force from the piston base, and therefore the forward force received by the piston base from the elastic body can be transmitted to the piston rod, and the piston head equipped on the piston rod can press the plunger. At the same time, since the piston rod is connected to the piston base so that its relative front-to-rear position with respect to the piston base can be changed, the piston head stop position can be adjusted. The method for connecting the piston rod and the piston base is not particularly limited, and for example, a method of connecting using a male and female thread structure, a method of connecting using a hydraulic cylinder structure, etc. can be used, but is not limited to these.

[0037] The "actuator" included in the needle-free syringe or needle-free injection system of the present invention is not particularly limited, and any component or device capable of generating a driving force can be used as the actuator. Examples of actuators that can be used include, but are not limited to, servo motors, stepping motors, linear motors, hydraulic actuators, pneumatic actuators, ultrasonic motors, etc. In the present invention, the first actuator drives the elastic body energy storage unit, and the second actuator drives the piston head stop position adjustment unit. However, in the case of a mechanism in which a single actuator can transmit driving force to both the elastic body energy storage unit and the piston head stop position adjustment unit, the first actuator and the second actuator may be the same actuator.

[0038] In the needle-free syringe or needle-free injection system of the present invention, the elastic body is charged by the elastic body charging unit and the piston head stop position is controlled by the piston head stop position adjustment unit. However, when continuously injecting injection liquid, manually repeatedly driving the elastic body charging unit places a heavy burden on the user. Furthermore, it is difficult to accurately control the piston head stop position by manually driving the piston head stop position adjustment unit. To prevent accidental injection of injection liquid when the user does not intend, it is preferable to perform a series of operations in a short period of time immediately after the user performs the injection operation, including moving the piston backward by the elastic body charging unit, adjusting the piston head stop position by the piston head stop position adjustment unit, and driving the piston forward by releasing the elastic body. However, it is impossible to perform these operations manually in a short period of time. Therefore, the needle-free syringe or needle-free injection system of the present invention essentially comprises a first actuator that drives the elastic body energy storage unit, a second actuator that drives the piston head stop position adjustment unit, and a control unit that controls these, and these repeatedly charge the elastic body by the elastic body energy storage unit, change the piston head stop position forward by the piston head stop position adjustment unit, and drive the piston forward by releasing the elastic body.This makes it possible to gradually press and advance the plunger that pushes out the injection liquid in the ampule, and repeatedly inject the injection liquid in a single ampule in multiple doses.

[0039] 1-2. First Embodiment Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. FIG. 1 is a schematic diagram showing the internal structure of a needle-free syringe according to a first embodiment of the present invention. As shown in FIG. 1, the needle-free syringe 1 of the present invention has a structure in which a machine casing main body 2 serves as the housing of the device, and various components are attached therein, such as a piston 5, an elastic body (coil spring) 6, an elastic body energy storage unit 7, a first actuator (motor) 8, a piston head stop position adjustment unit 9, a second actuator (motor) 10, and a control unit 11. An ampoule 3 can be attached to the front of the machine casing main body 2. The machine casing main body 2 has a generally cylindrical shape overall, with multiple steps in the front, resembling multiple cylinders of different diameters stacked on top of each other. In the first embodiment, the machine casing main body serves as the housing, but the present invention is not limited to this configuration. Any machine casing main body can be used as long as it can attach an ampoule to the front and has a piston attached thereto so as to be slidable back and forth.

[0040] 1-2-1. Ampoule As shown in FIG. 1 , the front of the casing body 2 is configured to allow attachment of an ampoule 3. The ampoule 3 is a disposable consumable item separate from the needleless syringe 1. Users purchase the ampoule 3 sealed in a sterilized package and attach it to the front opening of the casing body 2 for use. The ampoule 3 has a cylindrical cylinder 302 that contains an injection solution 301, and a small-diameter discharge nozzle 303 is provided at its front end. A plunger 304 is inserted into the cylinder 302, and by pushing the plunger 304, the injection solution 301 contained inside the cylinder 302 can be ejected from the discharge nozzle 303. A male thread 305 is formed at the rear of the cylinder 302, and is shaped to mate with a female thread 201 formed in the front opening of the casing body 2. The ampoule 3 can be attached to the front opening of the casing body 2 by mating the male thread with the female thread. The ampoule 3 is provided with a ring-shaped stopper 306, and when the male thread 305 of the cylinder 302 is turned into the female thread 201, the stopper 306 comes into contact with the front of the machine frame main body 2, and when a stronger force is applied to turn the cylinder 302, the elastic force of the stopper 306 is generated, increasing the frictional force and preventing the male thread 305 from rotating relative to the female thread 201. This prevents the ampoule 3 from loosening and also prevents the ampoule 3 from flying out due to the driving force of the piston.

[0041] 1-2-2. Piston As shown in FIG. 1 , a cylindrical piston syringe 4 is attached to the machine housing 2, and a piston 5 is provided therein so as to be able to slide back and forth. The piston 5 comprises a piston base 510 and a piston rod 520. The piston base 510 has a cylindrical shape whose outer circumferential surface contacts the inner circumferential surface of the piston syringe 4, and can slide back and forth inside the piston syringe 4. A groove (not shown) extending in the front-rear direction is provided on the inner circumferential surface of the piston syringe 4 as a piston guide. A protrusion on the outer circumferential surface of the piston base 510 slides along the piston guide, preventing the piston base 510 from rotating. A protruding piston follower 511 is provided on the piston base 510, and the piston follower 511 can receive a forward force from an elastic body (coil spring) 6. In addition, the piston follower 511 can receive a rearward force from the cam 750 of the elastic energy storage unit 7, which moves the piston base 510 rearward. A plurality of washers 512 can be attached to the piston base 510 adjacent to the piston follower 511, and the injection force (injection pressure) can be adjusted by changing the length of the elastic body (coil spring) 6 when the piston base is moved rearward. The elastic body (coil spring) 6 is compressed between the washers 512 and the machine casing main body 2. Therefore, when the piston base is moved rearward a certain distance, the more washers 512 there are, the more the elastic body (coil spring) 6 is compressed and the shorter its length becomes, so that more elastic energy can be stored and the injection force (injection pressure) can be increased.

[0042] The piston base 510 and the piston rod 520 are connected to each other by threading a female thread 513 of the piston base 510 into a male thread 521 of the piston rod 520. Therefore, the piston rod 520 can receive a forward force from the piston base 510, which receives force from the elastic body (coil spring) 6. Because a piston head 522 is provided at the front end of the piston rod 520, the forward force applied by the elastic body (coil spring) 6 is also transmitted to the piston head 522. Note that in FIG. 1 , the "forward direction" is indicated by the direction of an arrow. Therefore, when the piston base 510 is driven forward by the force of the elastic body (coil spring) 6, the piston head 522 presses the plunger 304, causing the injection liquid 301 in the ampule 3 to be ejected from the discharge nozzle 303.

[0043] The piston base 510 and the piston rod 520 are connected to each other via a female thread 513 and a male thread 521. Therefore, by rotating the piston base 510 and the piston rod 520 relative to each other, their relative positions can be changed forward and backward. This allows the position of the piston head 522 to be adjusted forward and backward. In the first embodiment, the piston base 510 is provided with a piston guide (not shown) to prevent the piston base 510 from rotating, while the piston rod 520 can be rotated by the driving force of the second actuator (motor) 10. However, the present invention is not limited to this configuration, and a structure in which the piston rod does not rotate but the piston base rotates instead may be used. Furthermore, as described above, the present invention may employ any structure in which the piston rod can receive a forward force from the piston base and is connected to the piston base so as to change its forward and backward position relative to the piston base.

[0044] 1-2-3. Elastic Body Energy Storage Unit As shown in FIG. 1, the needle-free syringe 1 of the present invention includes an elastic body energy storage unit 7. The cam 750 of the elastic body energy storage unit 7 presses the piston follower 511, moving the piston base 510 rearward and compressing the elastic body (coil spring) 6 to store energy. The elastic body energy storage unit 7 includes a rod 710, a ball bearing 720, a gear wheel 730, a base 740, and a cam 750. The rod 710 is a cylindrical component that serves as the rotation axis for rotating the gear wheel 730. The rod 710 is hollow, allowing the piston rod 520 to move freely back and forth within the hollow space. The rod 710 is inserted into the cylindrical ball bearing 720 and abuts against the inner circumferential surface of the ball bearing 720 via a ball, allowing smooth rotation. A large gear 730 is connected to the rod 710, and the large gear 730 rotates around the rod 710 as a rotation axis. The rod 710 and the large gear 730 rotate around an axis in the front-to-rear direction along which the piston slides. Because the ball bearing 720 abuts against the large gear 730 via balls, the large gear 730 can also rotate smoothly without being subjected to large frictional forces. An annular base 740 is provided on the large gear 730, and a cam 750 is provided on the surface of the base 740. As a result, the cam 750 also rotates around an axis in the front-to-rear direction.

[0045] The large gear 730 can rotate by receiving the driving force of the first actuator (motor) 8. That is, the rotational driving force of the first actuator (motor) 8 is transmitted to the large gear 730 by a gear 810 provided on a shaft 820 of the first actuator (motor) 8.

[0046] To explain the transmission of driving force by gears, FIG. 2A shows a cross-sectional view taken along a plane including dashed line C1-C2 in FIG. 1 . As shown in FIG. 2A , rod 710 is cylindrical and has a space inside that allows piston rod 520 to move freely. A large gear 730 is connected to rod 710, and a number of teeth 731 are provided on the outer periphery of large gear 730. A gear 810 for rotating large gear 730 is installed on the upper part of large gear 730, and rotates around shaft 820 by the driving force of first actuator (motor) 8. A number of teeth 811 are provided on the outer periphery of gear 810. When gear 810 rotates clockwise, at the portion where gear 810 and large gear 730 mesh, teeth 811 of gear 810 moving leftward press teeth 731 of large gear 730 leftward, causing large gear 730 to rotate counterclockwise. Conversely, when gear 810 rotates counterclockwise, large gear 730 rotates clockwise. The drive of first actuator (motor) 8 is controlled by control unit 11, and the rotation of large gear 730 can be freely controlled.

[0047] As shown in Figure 2 (A), the large gear 730 and the gear 810 are housed inside the cylindrical machine casing main body 2, preventing accidents such as being pinched between the gears. The lower part of the machine casing main body 2 is flat, allowing the needle-free syringe 1 to be placed stably on a workbench or the like. The machine casing main body 2 has two left and right sections joined together by fastening screws (not shown), and internal parts can be replaced or repaired by removing the fastening screws.

[0048] The cam 750 shown in FIG. 1 is a mechanism that can convert the rotational motion of the gear 730 into forward and backward motion of the piston. As shown in FIG. 1, the cam 750 abuts against the piston follower 511 of the piston base 510. The cam 750 has a semicircular, three-dimensional shape with a thickness that varies depending on the location. Because the piston follower 511 abuts against the cam 750 via a ball, the cam 750 can rotate smoothly. Because the piston base 510 is prevented from rotating by a piston guide (not shown), the point where the cam 750 abuts against the piston follower 511 moves on the cam 750. As the cam 750 rotates, the thickness of the cam 750 in the forward and backward direction at the point where it abuts against the piston follower 511 changes, thereby converting the rotational motion into forward and backward motion.

[0049] FIG. 3 shows the state in which the cam 750 and the piston follower 511 are in contact with each other and the change in the thickness of the cam. FIG. 3(A) is a schematic diagram of the state in which the cam 750 and the piston follower 511 are in contact with each other, as viewed from behind along the axis along which the piston in FIG. 1 slides. As shown in FIG. 3(A), an annular base 740 is provided on the gearwheel 730, and a cam 750 is provided on the surface of the base 740. The cam 750 has a semicircular, three-dimensional shape with a variable thickness, and a pair of identical cams 750 are formed on the base 740 at 180° intervals. A pair of piston followers 511 provided at the tip of the piston base 510 are in contact with the cams 750, and the piston followers 511 are pressed against the cams 750 by an elastic body (coil spring) 6. Therefore, the piston base 510 moves back and forth depending on the thickness of the cam at the point where the cam 750 and the piston follower 511 come into contact. When the piston base 510 moves back and forth, the piston rod 520 connected to the piston base 510 also moves back and forth. There are two points where the cam 750 and the piston follower 511 come into contact, but because the two cams 750 have the same three-dimensional shape, the thickness of the cam 750 at the points where the cam 750 and the piston follower 511 come into contact is the same at both points. The thickness of the cam 750 at the point where the cam 750 and the piston follower 511 come into contact changes with the rotation of the gear wheel 730. The angle by which the gear wheel 730 has rotated is indicated by the symbol θ.

[0050] FIG. 3B is a graph showing the change in the thickness of the cam 750 at the point where the cam 750 and the piston follower 511 contact each other as the gear 730 rotates. As shown in FIG. 3B, when the rotation angle θ of the gear 730 is 0°, the thickness of the cam 750 is 0, and the piston follower 511 contacts the base 740. When the gear 730 rotates and the rotation angle θ becomes 15°, the piston follower 511 first contacts the cam 750. As the rotation angle increases, the thickness of the cam 750 at the point where the cam 750 and the piston follower 511 contact each other increases. Then, when the rotation angle θ becomes 150°, the thickness of the cam 750 reaches its maximum value, G. FIG. 3A shows the state when the rotation angle θ of the gear 730 is 150°. As the thickness of the cam increases in this way, the piston base 510 moves rearward, compressing the elastic body (coil spring) 6 and allowing the elastic body energy storage section 7 to store energy in the elastic body.

[0051] As shown in FIG. 3B , as the rotation angle is further increased, the thickness of the cam 750 suddenly decreases to 0 at a rotation angle θ of 165°. As such, the cam 750 has a stepped shape, and the piston follower 511 suddenly drops from this step, receiving a force that causes the elastic body (coil spring) 6 to return to its original shape, accelerating and driving forward at high speed, before stopping when it reaches the base 740. In this way, the elastic body (coil spring) 6 can also be released by the elastic body energy storage unit 7, thereby driving the piston 5 forward at high speed. As described above, the elastic body energy storage unit 7 included in the needle-free syringe 1 of the first embodiment is a cam mechanism that can convert the rotational motion of the first actuator (motor) 8 into forward and backward motion of the piston, and by continuing the rotational motion, the elastic body (coil spring) 6 can be continuously charged and released.

[0052] 1-2-4. Piston Head Stop Position Adjusting Unit As shown in FIG. 1, the needle-free syringe 1 of the present invention is equipped with a piston head stop position adjusting unit 9, which uses the driving force of a second actuator (motor) 10 to rotate the piston rod 520 and change the relative position of the piston rod 520 with respect to the piston base 510 back and forth, thereby adjusting the piston head stop position. As shown in FIG. 1, the piston head stop position adjusting unit 9 is a mechanism including an internal gear 910 and a ball bearing 920. The internal gear 910 is cylindrical and has multiple teeth 911 that extend linearly in the front-to-rear direction and are provided facing inward, forming an internal gear. In contrast, the rear end of the piston rod 520 has multiple teeth 523 that extend linearly in the front-to-rear direction and are provided facing outward, forming a spur gear, which meshes with the teeth 911 of the internal gear 910. The internal gear 910 is inserted into a ball bearing 920 to allow smooth rotation, and is further connected to the shaft 1001 of the second actuator 10 so that it can be rotated by the driving force of the second actuator 10. With this structure, the rotational driving force of the second actuator (motor) 10 can be transmitted to the spur gear of the piston rod 520 via the internal gear 910, thereby rotating the piston rod 520. The driving of the second actuator (motor) 10 is controlled by the control unit 11, and the rotation of the internal gear 910 can be freely controlled in either direction.

[0053] To explain the transmission of driving force by gears, FIG. 2(B) shows a cross-sectional view taken along the plane including dashed line C3-C4 in FIG. 1 . As shown in FIG. 2(B), the internal gear 910 is cylindrical and houses the piston rod 520 therein. The internal gear 910 has a plurality of teeth 911 on its inner surface, which mesh with teeth 523 on the outer surface of the piston rod 520. Therefore, when the internal gear 910 is rotated clockwise by the second actuator (motor) 10, the piston rod 520 also rotates clockwise. Conversely, when the internal gear 910 is rotated counterclockwise, the piston rod 520 also rotates counterclockwise. The teeth 911 of the internal gear 910 and the teeth 523 of the piston rod 520 both have tooth traces that extend linearly in the front-to-rear direction, allowing the piston rod 520 to slide back and forth relative to the internal gear 910.

[0054] Next, as shown in FIG. 1 , the male thread 521 provided on the piston rod 520 is cut to be a right-handed thread, so that when the internal gear 910 is rotated clockwise, the piston rod 520 also rotates clockwise and moves forward relative to the piston base 510. Conversely, when the internal gear 910 is rotated counterclockwise, the piston rod 520 also rotates counterclockwise and moves backward relative to the piston base 510. In the first embodiment, the male thread 521 is cut to be a right-handed thread, but in the needle-free syringe of the present invention, it may be cut to be a left-handed thread. In this case, when the piston rod 520 is rotated counterclockwise, it moves forward relative to the piston base 510, and when it is rotated clockwise, it moves backward.

[0055] 1 shows a state in which the piston base 510 has moved rearward by the cam 750, storing energy in the elastic body (coil spring) 6, and FIG. 3B shows a state in which the rotation angle θ of the gear wheel 730 is 150°. If the gear wheel 730 is further rotated and the rotation angle θ exceeds 165°, as described above, the piston follower 511 suddenly drops from the step of the cam 750, releasing the energy of the elastic body (coil spring) 6, and the piston 5 is driven forward at high speed, after which it stops when the piston follower 511 reaches the base 740. The position of the piston head 522 at this point of stop is the "piston head stop position." In the case of FIG. 1, the distance (gap) between the piston head 522 and the plunger 304 is G, but the height of the cam 750 is also G. Therefore, even if the elastic body (coil spring) 6 is released, the piston head stops at the end position of the plunger 304, and the piston head 522 cannot press the plunger 304.

[0056] Therefore, to press the plunger 304 and inject the injection solution 301, it is necessary to change the piston head stop position to a position forward. This position change can be performed by the piston head stop position adjustment unit 9. That is, the control unit 11 shown in FIG. 1 controls the second actuator (motor) 10 to rotate the internal gear 910 clockwise a predetermined amount (a predetermined number of rotations) and move the piston rod 520 forward by a distance x. This allows the piston head stop position to be changed to a position moved forward by the distance x compared to the case shown in FIG. 1. When moving the piston rod 520 forward by the distance x, a piston rod position sensor 1301 connected to the control unit 11 via an electrical communication line (not shown) detects the approach of the piston head 522, thereby measuring the position of the piston head 522 in real time. Then, when it is determined that the piston head 522 has moved forward beyond the predetermined position, the control unit 11 immediately stops driving the second actuator (motor) 10 and stops the movement of the piston rod 520. This prevents the piston rod 520 from moving forward more than the distance x and injecting an excessive amount of liquid, and also prevents an accident in which the piston rod 520 moves too far forward, causing the piston head 522 to fly forward during injection and break the ampoule 3 or the front end of the machine frame main body 2.

[0057] FIG. 4 shows the operation of the internal structure of the needle-free syringe 1 when the piston head stop position is changed and the elastic body is released. FIG. 4(A) shows a state in which the piston head has moved forward from the state shown in FIG. 1. As shown in FIG. 4(A), compared to FIG. 1, the piston head 522 has moved forward by a distance x, and the distance (gap) between the piston head 522 and the plunger 304 has changed from G to G-x. Meanwhile, the position of the piston base 510 has not changed, and the relative position of the piston rod 520 with respect to the piston base 510 has changed forward by a distance x. Because FIG. 4(A) shows a state before the elastic body (coil spring) 6 is released, the position of the piston head 522 shown in FIG. 4(A) is not the "piston head stop position" according to the present invention. However, since the piston head 522 has moved forward by a distance x, the position at which the piston head stops when the elastic body (coil spring) 6 is released and the piston is driven forward (the "piston head stop position") has also changed forward by the distance x.

[0058] 4(B) shows a state in which the piston 5 stops after being driven forward by deenergizing the elastic body (coil spring) 6 from the state shown in FIG. 4(A). As shown in FIG. 4(B), the thickness of the cam at the point where the piston follower 511 abuts disappears, and the piston follower 511 abuts against the base 740. This corresponds to the state in FIG. 3(B) in which the rotation angle θ of the gear wheel 730 is 180°. As described above, when the rotation angle θ of the gear wheel 730 exceeds 165°, the piston follower 511 suddenly drops from the step of the cam 750, deenergizing the elastic body (coil spring) 6, driving the piston 5 forward at high speed, and then stopping when the piston follower 511 reaches the base 740. At this time, as shown in FIG. 4B, the piston head 522 collides with the plunger 304 at high speed, and the injection liquid 301 can be ejected from the discharge nozzle 303 at high speed.

[0059] As shown in FIG. 4(B), the needle-free syringe 1 is equipped with a piston base position sensor 1302 connected to the control unit 11 via an electric communication line (not shown). The piston base position sensor 1302 measures the position of the piston follower 511 in real time by detecting the approach of the piston follower 511. Then, when the control unit 11 measures that the piston base 510 has moved forward to a position where the piston follower 511 abuts against the pedestal 740, it immediately stops driving the first actuator (motor) 8. This makes it possible to stop the rotation of the gear wheel 730 at the correct position after injection is completed, and also makes it possible to prevent an accident such as an unintended next injection.

[0060] In FIG. 4A, because a gap exists between the piston head 522 and the plunger 304, during the initial release of the elastic body (coil spring) 6, the piston 5 is accelerated by the elastic body (coil spring) 6 without resistance, allowing it to collide with the plunger 304 at high speed. This causes the plunger 304 to move at high speed, and the piston head 522 pushes the plunger 304 in one go, ejecting the injection solution 301, until the piston follower 511 reaches the base 740 and stops. Thus, the presence of the gap allows the piston head 522 to act like a hammer striking the plunger 304, ejecting the injection solution at high speed, thereby enabling subcutaneous injection. The gap distance in FIG. 4A is G-x, but the piston head 522 moves forward by the cam thickness G and stops, so the plunger 304 can be pushed a distance x, as shown in FIG. 4B. Therefore, the amount of injection liquid per injection (x × cross-sectional area of ​​the injection liquid 301 in the ampoule 3) can be controlled by controlling the distance x by which the piston head 522 is moved forward by the control unit 11. Then, by determining the amount of injection liquid per injection, the number of times that the injection liquid 301 in a single ampoule 3 can be injected (length of the injection liquid 301 in the front-rear direction in the ampoule 3 / x) is also determined.

[0061] The greater the value of the distance x by which the piston head 522 is moved forward, the greater the amount of injection solution per injection, but the shorter the gap distance (G-x), the shorter the distance over which the piston head 522 is accelerated, resulting in a weaker initial impact force (injection pressure). Conversely, when the value of x is small, the amount of injection solution per injection decreases, but the longer the gap distance (G-x), the longer the distance over which the piston head 522 is accelerated, resulting in a stronger initial impact force (injection pressure). In areas where the skin is elastic and prone to bending (flexing), if the amount of injection solution is small, the amount of injection solution will run out before the skin bends, making it impossible to penetrate the skin. Therefore, it is effective to increase the value of x to increase the amount of injection solution and further push the injection solution into the bent skin, thereby penetrating the skin. Conversely, in areas where the skin is taut and hard, even if the amount of injection solution is large, if the initial impact force (injection pressure) is weak, the hard skin cannot be penetrated. Therefore, it is effective to increase the initial impact force (injection pressure) by decreasing the value of x, thereby breaking through the hard skin and allowing the injection solution to penetrate.

[0062] The elastic body (coil spring) 6, which was compressed as shown in Fig. 4(A) due to the energy storage of the elastic body, returns to its original state and becomes longer as shown in Fig. 4(B) when the elastic body is released. As shown in Fig. 4(B), the piston follower 511 abuts against the base 740 and stops, so the piston 5 does not move forward any further, and the plunger 304 is not pushed any further by the piston head 522. Therefore, after one injection of the injection liquid is completed, the needleless syringe 1 can be safely put on standby without causing accidental injection by maintaining the state shown in Fig. 4(B).

[0063] When the next injection of the injection liquid is to be performed, the step of energizing the elastic body as shown in FIG. 1, the step of changing the piston head stop position as shown in FIG. 4(A), and the step of deenergizing the elastic body as shown in FIG. 4(B) can be performed consecutively in a short time to perform the second injection. Note that in the second injection, each step is performed with the position of the piston head 522 moved further forward by x compared to FIG. 1 and FIGS. 4(A) and (B). The third and subsequent injections can also be performed using this series of steps. By repeating this series of steps multiple times, the injection liquid in a single ampule can be repeatedly injected in multiple doses.

[0064] After all of the injection liquid in the ampoule 3 has been injected, the second actuator (motor) 10 is driven in reverse rotation to rotate the internal gear 910 counterclockwise a predetermined amount (a predetermined number of rotations), moving the piston rod 520 backward and returning it to its initial position. The empty ampoule 3 is then removed, and a new ampoule 3 filled with the injection liquid 301 is installed, allowing injection of the injection liquid to be resumed. When moving the piston rod 520 backward to return it to its initial position, the piston rod position sensor 1301 measures the position of the piston rod 520 in real time. When it is determined that the piston rod 520 has moved rearward from its initial position, the control unit 11 immediately stops driving the second actuator (motor) 10 and stops the rearward movement of the piston rod 520. This prevents the piston rod 520 from moving too far rearward, causing the rear end of the piston rod 520 to collide with the bottom of the internal gear 910 when charging the elastic body (coil spring) 6, resulting in damage to components.

[0065] 1, the needle-free syringe 1 of the first embodiment includes a control unit 11, which controls the driving of the first actuator (motor) 8 and the second actuator (motor) 10. From the control unit 11 to the first actuator (motor) 8, power and a command signal for controlling the actuator are supplied via a cable 1101. Similarly, from the control unit 11 to the second actuator (motor) 10, power and a command signal for controlling the actuator are supplied via a cable 1102. Power is supplied to the control unit 11 from the outside via a power cable 14, and the control unit 11 uses the power from the outside to process information and supply power to the first actuator (motor) 8 and the second actuator (motor) 10.

[0066] The first actuator (motor) 8 and the second actuator (motor) 10 each include a drive circuit, a control circuit, and a rotation speed detector (not shown). Based on a command signal supplied from the control unit 11 and a detection signal measured by the rotation speed detector, the control circuit calculates the voltage required to change the current motor rotation speed per unit time, as determined by the detection signal, to the rotation speed per unit time specified by the command signal, thereby generating a drive voltage signal and supplying it to the drive circuit. The drive circuit applies voltage to the actuator based on the drive voltage signal received from the control circuit, thereby driving the actuator. The control unit 11 generates the command signal using an information processing device (not shown). The information processing device performs predetermined information processing according to commands from a control program stored in a storage device (not shown), and generates the command signal.

[0067] In the first embodiment, the control unit 11 supplies command signals to the first actuator (motor) 8 and the second actuator 10 to control the drive of these actuators, but the needle-free syringe or needle-free injection system, and drive method and control program of the present invention are not limited to this aspect, and for example, the drive of the actuators may be controlled by supplying a voltage-controlled current to the actuators from the control unit 11. Furthermore, in the first embodiment, the command signals are generated by the information processing device and control program included in the control unit 11, but the needle-free syringe or needle-free injection system and drive method of the present invention are not limited to this aspect, and for example, the actuators may be controlled by only a control circuit and a drive circuit, without using an information processing device or a control program.

[0068] 1, the control unit 11 is provided with an ejection button 1201 and an ejection liquid volume changeover switch 1202 as an interface that allows the user to operate and set the needle-free syringe 1. When the user presses the ejection button 1201, the control unit 11 receives the signal and drives the first actuator (motor) 8 and the second actuator (motor) 10 to perform the following steps 1A) to 1C) consecutively in a short period of time. 1A) A step of driving the first actuator (motor) 8 and moving the piston base 510 backward using the elastic body energy storage unit 7, thereby energy-storing the elastic body (coil spring) 6; 1B) A step of driving the second actuator (motor) 10 and moving the relative position of the piston rod 520 with respect to the piston base 510 forward by a distance x using the piston head stop position adjustment unit 8; 1C) A step of further driving the first actuator (motor) 8 and releasing energy from the elastic body (coil spring) 6 using the elastic body energy storage unit 7, thereby driving the piston 5 forward and pressing the plunger 304 with the piston head 522, thereby injecting the injection liquid 301 in the ampoule 3; In this way, the user can automatically inject the injection liquid by the simple operation of pressing the injection button 1201 of the needle-free syringe 1. The user can then repeatedly inject the injection liquid from a single ampule by pressing the injection button 1201 multiple times, thereby enabling the injection liquid to be injected in multiple separate doses. Also, if the user presses the injection button 1201 multiple times in succession each time the injection liquid is to be injected, the user can easily and automatically shoot the injection liquid in rapid succession using the driving force of the actuator, without having to repeatedly compress the elastic body (coil spring) 6 manually (by hand).

[0069] Upon receiving a signal indicating that the user has pressed the injection button 1201, the control unit 11 can simultaneously execute the above-described steps 1A) and 1B). This reduces the injection time. In step 1A, the piston base 510 is moved rearward by the elastic energy storage unit 7 shown in FIG. 1 , while in step 1B, the piston head stop position adjustment unit 8 moves the relative position of the piston rod 520 with respect to the piston base 510 forward. Therefore, if the speed at which the piston rod 520 moves forward with respect to the piston base 510 in step 1B) is set faster than the speed at which the piston base 510 moves rearward in step 1A, the piston head 522 may move forward and press the plunger 304, resulting in leakage of the injection solution 301 before injection. To prevent this, the control unit 11 drives the first actuator (motor) 8 and the second actuator (motor) 10 so that the speed at which the piston rod 520 moves forward relative to the piston base 510 in step 1B) is slower than the speed at which the piston base 510 moves backward in step 1A). Alternatively, the position of the piston rod 520 may be measured in real time by the piston rod position sensor 1301, and when it is detected that the piston rod 520 has moved further forward than a predetermined position, the control unit 11 may immediately stop driving the second actuator 10.

[0070] The user can set the injection volume per injection to either "0.05 ml" or "0.1 ml" using the injection volume changeover switch 1202. When the injection volume per injection is set to "0.05 ml", the distance x for changing the piston head stop position to a forward position in step 1B) above is "x (cm) = 0.05 ml (cm ３ ) / cross-sectional area of ​​injection solution 301 (cm ２)." The drive amount of the second actuator (motor) 10 is controlled so that the distance x is set as described above, and the piston head stop position is changed to a position in the forward direction. As a result, when the elastic body (coil spring) 6 is released, the piston head 522 pushes the plunger 304 into the ampoule 3 by the distance x, and the amount of injected liquid is 0.05 ml (= x × cross-sectional area of ​​the injection liquid 301). Since the injection liquid filled in the ampoule is 0.4 ml, eight injections can be performed. When the amount of injection liquid per injection is set to "0.1 ml", the distance x is expressed as "x (cm) = 0.1 ml (cm ３ ) / cross-sectional area of ​​injection solution 301 (cm ２ ) and the plunger 304 is pushed in twice as far as when the injection volume is set to "0.05 ml," resulting in an injection volume of "0.1 ml." The injection volume is then increased to four times, half the number of times that when the injection volume per injection is set to "0.05 ml."

[0071] 1-2-6. Control Program In the control unit 11 provided in the needle-free syringe 1 of the first embodiment, as explained in the section "1-2-5. Control Unit", the information processing device performs predetermined information processing and generates a command signal in accordance with instructions from the control program. Specifically, the control program causes the information processing device to execute information processing including the following essential steps 1A') to 1C') 1A') a step of generating a command signal to drive the first actuator (motor) 8 a predetermined amount (predetermined number of rotations) in order to charge the elastic body (coil spring) 6; 1B') a step of generating a command signal to drive the second actuator (motor) 10 a predetermined amount (predetermined number of rotations) in order to change the piston head stop position to a forward position by a predetermined distance x; 1C') a step of generating a command signal to drive the first actuator (motor) 8 a predetermined amount (predetermined number of rotations) in order to release the elastic body (coil spring) 6;

[0072] The control program in the first embodiment includes, as a part thereof, an injection control program that controls the operation of injecting an injection liquid in response to the user's operation of an injection button. More specifically, this injection control program causes an information processing device to execute the information processing shown in the flowchart of Fig. 5. As shown in Fig. 5, the flow of information processing by the injection control program in the first embodiment begins with "Start." When the power cable 14 of the needle-free syringe 1 shown in Fig. 1 is inserted into a power outlet (not shown) and a start button (not shown) is pressed, the information processing device provided in the control unit 11 starts up and starts information processing by the injection control program.

[0073] The first step S01 in the information processing flow shown in FIG. 5 is a step of performing information processing to detect the user's operation of the ejection button 1201. In the information processing of step S01, if a signal that the ejection button 1201 has been pressed is not received (in the case of "No"), the process waits while repeating detection. If a signal that the ejection button 1201 has been pressed is received (in the case of "Yes"), the process proceeds to the next step S02A. Step S02A is a required step corresponding to the above-mentioned step 1A'), and is a step of performing information processing to generate a command signal for driving the first actuator (motor) 8 a predetermined amount (predetermined number of rotations) in order to store energy in the elastic body (coil spring) 6. Here, the predetermined amount (predetermined number of rotations) for driving the first actuator (motor) 8 is the number of rotations of the gear 810 required to rotate the large gear 731 shown in FIG. 2A by 180°. The command signal is a signal that commands the number of rotations of the motor per unit time, and by generating this command signal for a predetermined time and transmitting it to the first actuator (motor) 8, it becomes possible to drive the first actuator (motor) 8 by a predetermined amount (predetermined number of rotations). When the command signal is generated in step S02A shown in Fig. 5 and transmission of the command signal to the first actuator (motor) 8 is started, driving of the first actuator (motor) 8 begins. After generating the command signal in step S02A and starting transmission of the command signal, the process proceeds to the next step S03B.

[0074] Step S03B shown in FIG. 5 is a required step corresponding to step 1B' described above. This step performs information processing to generate a command signal for driving the second actuator (motor) 10 a predetermined amount (predetermined number of rotations) to shift the piston head stop position forward by a predetermined distance x. As explained in the section "1-2-5. Control Unit," the distance x is determined to a different value depending on whether the injection volume per injection is set to "0.05 ml" or "0.1 ml." When the internal gear 910 shown in FIG. 1 rotates clockwise, the piston rod 520 also rotates clockwise, moving the piston rod 520 forward relative to the piston base 510. The number of rotations of the internal gear 910 required to move the piston rod 520 forward by the distance x is the "predetermined amount (predetermined number of rotations)" in step S03B. Therefore, in step S03B, the set value for the injection volume per injection is read from the storage device, and information processing is performed to determine the required number of rotations of the internal gear 910 corresponding to that set value, followed by information processing to generate a command signal. The command signal is a signal that commands the number of rotations of the motor per time. In step S03B, the command signal is generated for a predetermined time and transmitted to the second actuator (motor) 10, enabling drive of a predetermined amount (predetermined number of rotations). When the command signal is generated in step S03B shown in FIG. 5 and transmission of the command signal to the second actuator (motor) 10 is initiated, the second actuator (motor) 10 is also driven, in addition to the first actuator (motor) 8, thereby simultaneously storing energy in the elastic body (coil spring) 6 and shifting the piston head stop position forward. After generating the command signal and initiating transmission of the command signal in step S03B, the process proceeds to the next step S041.

[0075] Steps S041, S051, S042, and S052 shown in FIG. 5 are steps for performing information processing to determine the timing to stop driving the first actuator (motor) 8 and the second actuator (motor) 10. Step S041 performs information processing to determine whether the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations). Specifically, the information processing determines whether a predetermined time has elapsed since the command signal generated in step S02A was transmitted to the first actuator (motor) 8. If the predetermined time has not elapsed, the first actuator (motor) 8 has not been driven a predetermined amount (predetermined number of rotations), resulting in a "Yes" determination, and the process proceeds to step S051. Conversely, if the predetermined time has elapsed, the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations), resulting in a "No" determination, and the process proceeds to step S061, where generation of the command signal for driving the first actuator (motor) 8 is stopped. This stops the driving of the first actuator (motor) 8. Step S051 is a step of performing information processing to determine whether the second actuator (motor) 10 has been driven a predetermined amount (predetermined number of rotations) or whether the piston head 522 has moved forward a distance x. Specifically, the information processing determines whether a predetermined time has elapsed since the command signal generated in step S03B was transmitted to the second actuator (motor) 10. At the same time, based on position information of the piston head 522 measured by the piston rod position sensor 1301 shown in FIG. 1 , the distance the piston head 522 has moved forward is calculated compared to the distance before the command signal for driving the second actuator (motor) 10 was generated, and the information processing determines whether this value has reached x. Then, as shown in FIG. 5 , if it is determined that the second actuator (motor) 10 has not been driven a predetermined amount (predetermined number of rotations) and the piston head 522 has not moved forward a distance x, the determination is made "No" and the process returns to step S041.Otherwise, that is, if it is determined that the second actuator (motor) 10 has been driven a predetermined amount (a predetermined number of rotations) or that the piston head 522 has moved forward by the distance x, the determination is "Yes," and the process proceeds to step S071, where the generation of a command signal for driving the second actuator (motor) 10 is stopped. This stops the driving of the second actuator (motor) 10. As described above, the information processing of steps S041 and S051 is repeated until either the first actuator (motor) 8 or the second actuator (motor) 10 is stopped.

[0076] If the drive of the first actuator (motor) 8 is stopped in step S061 shown in FIG. 5 , the process proceeds to step S052, where a determination is made by information processing similar to that in step S051. If the determination in step S052 is "Yes," the process proceeds to step S072, where the generation of a command signal for driving the second actuator (motor) 10 is stopped. This stops the drive of the second actuator (motor) 10, and the drive of both the first actuator (motor) 8 and the second actuator (motor) 10 is stopped. On the other hand, if the drive of the second actuator (motor) 10 is stopped first in step S071, the process proceeds to step S042, where a determination is made by information processing similar to that in step S041. If the determination in step S042 is "Yes," the process proceeds to step S062, where the generation of a command signal for driving the first actuator (motor) 8 is stopped. This stops the drive of both the first actuator (motor) 8 and the second actuator (motor) 10.

[0077] As described above, steps S041, S051, S042, and S052 enable appropriate determination of the timing to stop driving the first actuator (motor) 8 and the second actuator (motor) 10. This allows the driving of the first actuator (motor) 8 to be stopped when the elastic body (coil spring) 6 has been fully charged, and the driving of the second actuator (motor) 8 to be stopped when the piston head stop position has been shifted forward by the predetermined distance x. In the injection control program of the first embodiment, as in steps S051 and S052, it is determined whether the piston head 522 has moved forward by the distance x based on the position information of the piston head 522 measured by the piston rod position sensor 1301. However, this determination is not essential, and the timing to stop the second actuator (motor) 10 can be appropriately determined simply by determining whether the second actuator (motor) 10 has been driven a predetermined amount (a predetermined number of rotations). In the injection control program of the first embodiment, in addition to this determination, a double determination is made by adding a determination based on the position information measured by the piston rod position sensor 1301, thereby preventing an accident in which the piston head 522 jumps forward during injection and breaks the ampoule 3 or the front end of the machine frame main body 1, thereby improving the safety of the needleless syringe 1.

[0078] After stopping the drive of both the first actuator (motor) 8 and the second actuator (motor) 10 in step S062 or step S072 shown in FIG. 5 , the process proceeds to step S08C. Step S08C is a required step corresponding to step 1C' described above, and is a step in which a command signal is generated to drive the first actuator (motor) 8 a predetermined amount (predetermined number of rotations) in order to deenergize the elastic body (coil spring) 6. Here, the predetermined amount (predetermined number of rotations) for driving the first actuator (motor) 8 is the number of rotations of the gear 810 required to rotate the large gear 730 shown in FIG. 2A by 180°. The command signal is a signal that commands the number of motor rotations per time. By generating this command signal for a predetermined time and transmitting it to the first actuator (motor) 8, it is possible to drive the first actuator (motor) 8 by the predetermined amount (predetermined number of rotations). After generating the command signal in step S08C and starting transmission of the command signal, the process proceeds to the next step S09.

[0079] Step S09 shown in FIG. 5 is a step for performing information processing to determine the timing to stop driving the first actuator (motor) 8. In step S09, information processing is performed to determine whether the first actuator (motor) 8 has driven a predetermined amount (predetermined number of rotations) or whether the piston follower 511 has contacted the base. Specifically, the information processing determines whether a predetermined time has elapsed since the command signal generated in step S08C was transmitted to the first actuator (motor) 8. At the same time, the information processing determines whether the piston follower 511 has reached a position where it contacts the base 740, based on position information of the piston follower 511 measured by the piston base position sensor 1302 shown in FIG. 1. Then, if the information processing of step S09 determines that the first actuator (motor) 8 has not been driven a predetermined amount (predetermined number of rotations) and that the piston follower 511 has not reached a position where it contacts the pedestal 740 (if the determination is "No"), the information processing of step S09 is repeated. In other cases, that is, if it is determined that the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations) or that the piston follower 511 has reached a position where it contacts the pedestal 740, the determination is "Yes" and the process proceeds to step S10, where the generation of a command signal for driving the first actuator (motor) 8 is stopped. This allows the driving of the first actuator (motor) 8 to be stopped at an appropriate timing when the ejection of the injection solution 301 due to the release of the elastic body (coil spring) 6 is completed.

[0080] As described above, in step S09 of the injection control program of the first embodiment, it is determined whether or not the piston follower 511 has reached a position where it abuts against the base 740, based on the position information of the piston follower 511 measured by the piston base position sensor 1302. However, this determination is not essential, and the timing to stop the first actuator (motor) 8 can be appropriately determined simply by determining whether or not the first actuator (motor) 8 has been driven a predetermined amount (predetermined number of rotations). In addition to this determination, the injection control program of the first embodiment also makes a determination based on the position information measured by the piston base position sensor 1302, thereby making a double determination. This prevents an accident in which the rotation of the large gear 730 shown in FIG. 4 continues after injection is completed, resulting in an unintended next injection, thereby improving the safety of the needle-free syringe 1.

[0081] After stopping the drive of the first actuator (motor) 8 in step S10 shown in FIG. 5 , the process proceeds to step S11, where information processing is performed to increment the value of variable s, which counts the number of injections. Variable s, which counts the number of injections, is recorded in an information storage device included in the control unit 11. Variable s is used to count and display the number of injections. Specifically, an injection count display program, which is part of the control program, reads variable s and displays on a liquid crystal display device (not shown) included in the needle-free syringe 1 the number of injections performed since a new ampoule was set, along with the number of injections remaining with a single ampoule ("8 times" or "4 times"). This allows the user to grasp the number of injections performed on the patient and the number of injections remaining with the same ampoule. Variable s is also used for information processing required for operations after injection. Specifically, when the information processing of step S11 shown in Fig. 5 is completed and the program reaches "END," if the variable s has not reached the number of times that can be injected with a single ampule, the injection control program returns to "START" in the flowchart and resumes the information processing flow. On the other hand, if the variable s has reached the number of times that can be injected with a single ampule, an initialization program, which is part of the control program, drives the second actuator (motor) 10 shown in Fig. 1 in reverse rotation to move the piston rod 520 backward and return it to its initial position, and performs information processing to set the value of the variable s to 0. By driving the needleless syringe 1 through the above information processing, it becomes possible to repeatedly inject the injection liquid 301 in a single ampule 3 in multiple doses.

[0082] 1-3. Second Embodiment Fig. 6 is a schematic diagram showing a needle-free injection system according to a second embodiment of the present invention. As shown in Fig. 6, the needle-free injection system 1S according to the second embodiment is a system comprising a combination of multiple devices, such as a multi-step injector 1U, a control box 11B, and a foot switch 15, and components that connect them.

[0083] Similar to the needleless syringe 1 of the first embodiment shown in FIG. 1 , the multi-step injector 1U includes a piston, an elastic body (coil spring), an elastic body energy storage unit, a first actuator (motor), a piston head stop position adjustment unit, and a second actuator (motor) within the housing body, and an ampoule can be attached to the front of the housing body. However, the multi-step injector 1U does not include a control unit; instead, the control unit is provided within a separate control box 11B. A cord 1103 connecting the control box 11B and the multi-step injector 1U supplies power to the multi-step injector 1U and enables electrical communication between the first and second actuators (motors) and various sensors within the multi-step injector 1U and the control unit within the control box 11B. Similar to the control unit of the needle-free syringe of the first embodiment, the control unit inside the control box 11B controls the driving of the first and second actuators (motors) to operate the multi-step injector 1U, thereby enabling repeated injection of the injection liquid in a single ampule in multiple divided doses. A cord 1104 connecting the control box 11B to the foot switch 15 enables electrical communication between the control unit inside the control box 11B and the foot switch 15. In the needle-free syringe of the first embodiment, the injection liquid is automatically injected by the user pressing the injection button. In the needle-free injection system 1S of the second embodiment, the injection liquid is automatically injected from the multi-step injector 1U by the user stepping on the foot switch 15. The multi-step injector 1U is heavy and must be lifted with both hands, but using the foot switch 15 makes the injection operation easier.

[0084] As shown in FIG. 6 , the control box 11B is equipped with a power switch 1105, which, when switched ON, supplies power to the multi-step injector 1U and the control unit inside the control box 11B. The control box 11B also has a touch panel 1106, which displays various information required by the user and allows the user to operate the device via the touch panel 1106. The touch panel 1106 displays the number of injections that can be made from a single ampule as the "set number," and the number of injections made after replacing the ampule as the "operation number." This allows the user to grasp the number of injections already given to patients and the number of injections remaining that can be made from the same ampule.

[0085] As shown in FIG. 6 , the setting condition "0.4 ml 8 shots" is displayed in the upper left portion of the touch panel 1106. Here, "0.4 ml" indicates that the initial volume of injection liquid in the ampule is 0.4 ml, and "8 shots" indicates that the injection liquid in one ampule can be injected 8 times. This setting condition can be changed by the user pressing the "Settings" button in the lower left portion of the touch panel 1106. When the user presses the "Settings" button, the screen of the touch panel 1106 switches to a setting condition selection screen (not shown), and the user can change the setting condition by touching one of the setting condition options displayed on the setting condition selection screen. If the initial volume of injection fluid in the ampule differs, the initial position of the plunger that pushes the injection fluid out of the ampule will differ. Therefore, if the position of the piston rod (piston head) is not initialized to match this position, a "blank shot" (no injection) may occur, where the injection fluid is not injected even when the injection operation is performed. Furthermore, when the ampule is attached to the front end of the multi-step injector 1U, the plunger may be pressed by the piston head, causing the injection fluid to leak. Therefore, the control unit inside the control box 11B initializes the position of the piston rod (piston head) according to the initial volume of injection fluid in the ampule set by the user. The control unit inside the control box 11B also adjusts the amount of injection fluid per injection by changing the distance by which the piston head stops after each injection, depending on the number of injections that can be injected by the user, thereby enabling the injection fluid to be injected the number of times set by the user.

[0086] As shown in FIG. 6 , a vacuum attachment 1610 is attached to the front end of the multi-step injector 1U. One end of a suction tube 1621 is attached to the vacuum attachment 1610, and the other end of the suction tube 1621 is attached to an aspirator 1620. The aspirator 1620 is provided on top of the control box 11B and is equipped with a vacuum pump therein. The air inside the vacuum attachment 1610 can be sucked through the suction tube 1621 to create a negative pressure lower than atmospheric pressure. To generate negative pressure using the aspirator 1620, the "Suction" button displayed on the touch panel 1106 is touched and turned "ON," and suction by the vacuum pump of the aspirator 1620 begins.

[0087] FIG. 7 is a schematic diagram showing the cross-sectional structure of the front end of a multi-step injector with a vacuum attachment attached and how to use it. FIG. 7(A) shows the state before the vacuum attachment is attached to the skin, and FIG. 7(B) shows the state after the vacuum attachment is attached to the skin. As shown in FIG. 7(A), the vacuum attachment 1610 has a cylindrical shape with two open ends. The inner diameter of the rear open end is slightly larger than the outer diameter of the front end of the casing body 2 of the multi-step injector 1U. This allows the rear open end of the vacuum attachment 1610 to be removably attached by fitting it into the front end of the casing body 2 of the multi-step injector 1U. An ampoule 3 is attached to the front end of the casing body 2, and a space is formed around the ampoule 3 by surrounding it with the vacuum attachment 1610.

[0088] Conventional needle-free syringe attachments also have a similar shape, and by attaching them to the front end of the needle-free syringe and pressing the open end of the attachment firmly against the skin, loose skin can be made taut, making it easier to inject the injection solution subcutaneously. However, pressing the attachment too hard against the skin can cause pressure pain to the patient, which is a major problem, especially when injecting into the delicate facial area.

[0089] As shown in Fig. 7(A), the vacuum attachment 1610 used in the needle-free injection system 1S of the second embodiment has an attachment port to which a suction tube 1621 can be attached. The suction tube 1621 is connected to an aspirator 1620, and a vacuum pump provided in the aspirator 1620 can suck air to reduce the pressure in the internal space surrounded by the vacuum attachment 1610. As shown in Fig. 7(A), the surface of the skin 17 into which the injection liquid 301 is to be injected is in a loose state. Even if the injection liquid 301 is ejected toward the skin 17 at high speed, the loose skin 17 absorbs the injection liquid 301 while significantly deforming, and as a result, the kinetic energy of the injection liquid 301 is absorbed, which may prevent the injection liquid 301 from being injected subcutaneously.

[0090] Therefore, by bringing the open end of vacuum attachment 1610, the interior of which has been decompressed, close to the skin, as shown in Figure 7(B), skin 17 is adsorbed to the vacuum attachment, and skin 17 is further sucked into the decompressed interior of vacuum attachment 1610, thereby pulling the loose skin 17 and making the surface of skin 17 tightly taut. Skin 17 with a tightly taut surface is less likely to deform and is therefore unable to absorb the kinetic energy of injection solution 301. Furthermore, because skin 17 is stretched by being pulled, the epidermis and dermis become thinner. Therefore, when plunger 304 is pressed with piston head 522 to eject injection solution 301 at high speed, injection solution 301 can be injected subcutaneously, allowing injection solution 301 to be diffused subcutaneously.

[0091] As shown in Figure 7(B) , vacuum attachment 1610 is provided with air hole 1611. This air hole 1611 can be used to adjust the reduced pressure state within vacuum attachment 1610. As shown in Figure 7(B) , when air hole 1611 is blocked with finger 18, the pressure within vacuum attachment 1610 can be strongly reduced, and skin 17 can be sucked into vacuum attachment 1610. After subcutaneous injection of injection solution 301 is completed, finger 18 can be removed from air hole 1611 to relieve the reduced pressure within vacuum attachment 1610 and release skin 17 from suction to vacuum attachment 1610.

[0092] In the second embodiment of the needle-free injection system 1S, the control unit is not located in the multi-step injector 1U shown in FIG. 6 , but in a control box 11B, which is a separate device. The present invention is not limited to this embodiment, and the first actuator and / or the second actuator may also be located in the control box 11B. In this case, the first actuator and / or the second actuator may be a hydraulic actuator, a pneumatic actuator, or an actuator that transmits power via a wire. A path for oil, air, or a wire is provided in the cord 1103 to transmit power generated by driving the actuator in the control box 11B to the elastic energy storage unit and / or the piston head stop position adjustment unit in the multi-step injector 1U. This configuration further reduces the weight of the multi-step injector 1U when held by the user.

[0093] 2. Method for Driving a Needle-Free Syringe or Needle-Free Injection System The method for driving a needle-free syringe or needle-free injection system of the present invention is the method according to items [9] to

[13] described in [Summary of the Invention]. The driving method of the present invention is characterized by repeatedly performing the following steps when driving a needle-free syringe or needle-free injection system that uses an elastic body such as a spring: A) charging the elastic body using an elastic body charging unit that charges the elastic body by moving the piston backward and a first actuator that drives the elastic body charging unit, B) changing the piston head stop position to a forward position using a piston head stop position adjustment unit that adjusts the piston head stop position where the piston head stops when the charged elastic body is released and the piston is driven forward and a second actuator that drives the piston head stop position adjustment unit, C) driving the piston forward by releasing the elastic body, and pressing the plunger with the piston head of the piston, thereby injecting the injection liquid in the ampule. By driving the needle-free syringe or needle-free injection system in this manner, the plunger that pushes out the injection liquid in the ampule is gradually pressed forward by the piston head, making it possible to repeatedly inject the injection liquid in a single ampule in multiple doses.

[0094] In the driving method of the present invention, "repeated" means performing steps A) to C) multiple times until all of the injection liquid in the ampoule is injected. Therefore, steps A) to C) may be performed multiple times consecutively within a short period of time, or multiple injections may be performed with a long interval between each injection. Details of the driving method of the present invention are as described in detail in the chapter "1. Needle-free syringe or needle-free injection system" above, where the operation of each component of the needle-free syringe or needle-free injection system is explained in detail.

[0095] 3. Control Program The control program of the present invention is the control program according to items

[14] to

[17] described in the "Summary of the Invention." The control program of the present invention is a program that causes a control unit included in the needle-free syringe or needle-free injection system of the present invention to execute specific information processing. The control program of the present invention may be stored in a storage device included in the needle-free syringe or needle-free injection system, and by reading the control program, the specific information processing described in the control program may be executed by an information processing device included in the control unit. The control program of the present invention may also be stored in a storage device of a server and downloaded to a mobile device or the like via the Internet, causing the mobile device or the like to function as the control unit of the needle-free injection system. The control program of the present invention is not limited thereto, but may be, for example, a program that includes as part thereof an injection control program that executes information processing of the flow shown in the above section "1-2-6. Control Program" and FIG. 5. Furthermore, the control program of the present invention may include, in addition to an injection control program that controls the operation of injecting the injection solution, a program that realizes other functions, such as an injection count display program, as described in the "1-2-6. Control Program" section as an example.

[0096] The needle-free syringe or needle-free injection system, and the drive method and control program for the needle-free syringe or needle-free injection system of the present invention are inventions relating to medical, veterinary or experimental equipment, and the drive method and control program for said equipment, and are not inventions relating to methods for treating or diagnosing humans, and are therefore inventions that can be used industrially.

[0097] 1, 1A Needle-free syringe 1S Needle-free injection system 1U Multi-step injector 2 Machine frame body 201 Female thread 3, 3A Ampoule 301 Injection solution 302 Cylinder 303 Discharge nozzle 303A Discharge port 304, 304A Plunger 305 Male thread 306 Stopper 4 Piston syringe 5, 5A Piston 510 Piston base 511 Piston follower 512 Washer 513 Female thread 520 Piston rod 521 Male thread 522, 522A Piston head 523 Teeth 6 Elastic body (coil spring) 6A Spring 7 Elastic body energy storage section 710 Rod 720 Ball bearing 730 Gear wheel 731 Teeth 740 Base 750 Cam DESCRIPTION OF SYMBOLS 8 First actuator (motor) 810 Gear 811 Teeth 820 Shaft 9 Piston head stop position adjustment unit 910 Internal gear 911 Teeth 920 Ball bearing 10 Second actuator (motor) 11 Control unit 11B Control box 1101 Cable 1102 Cable 1103 Cord 1104 Cord 1105 Power switch 1106 Touch panel 1201 Injection button 1202 Injection liquid amount changeover switch 1210A Trigger 1211A Trigger finger 1212A Push end 1220A Safety lock 1301 Piston rod position sensor 1302 Piston base position sensor 14 Power cable 15 Foot switch 1610 Vacuum attachment 1611 Air hole 1620 Aspirator 1621 Suction tube 17 Skin 18 Finger

Claims

1. A needle-free syringe or needle-free injection system having a machine case main body to the front of which an ampoule having a plunger for pushing out the injection liquid therein can be attached, a piston provided on the machine case main body so as to be slidable back and forth, and an elastic body that applies a forward force to the piston, and which can inject the injection liquid in the ampoule by pressing the plunger with the piston head of the piston by releasing the stored elastic body and driving the piston forward, the needle-free syringe or needle-free injection system comprising: an elastic body storage unit that stores energy in the elastic body by moving the piston backward; a first actuator that drives the elastic body storage unit; a piston head stop position adjustment unit that adjusts the piston head stop position where the piston head stops when the stored elastic body is released and the piston is driven forward; a second actuator that drives the piston head stop position adjustment unit; and a control unit that controls the first actuator and the second actuator, wherein the piston has a piston base to which a forward force is applied by the elastic body, and a piston rod equipped with the piston head, the piston rod is connected to the piston base so that it can receive a forward force from the piston base and can change its position forward or backward relative to the piston base; the piston head stop position adjustment unit can adjust the piston head stop position by changing the position of the piston rod forward or backward relative to the piston base using the driving force of the second actuator; and the control unit controls the driving of the first actuator and the second actuator to repeatedly charge the elastic body by the elastic body charge unit, change the position of the piston head stop position forward by the piston head stop position adjustment unit, and drive the piston forward by releasing the elastic body.

2. The needle-free syringe or needle-free injection system according to claim 1, further comprising an interface for setting the number of injections per ampoule or the amount of injection liquid per injection, wherein the control unit controls the distance by which the piston head stop position is moved forward by controlling the drive amount of the second actuator in accordance with the number of injections per ampoule or the amount of injection liquid per injection set by a user via the interface.

3. The needle-free syringe or needle-free injection system according to claim 1 or 2, wherein the piston rod and the piston base are connected to each other by a male and female thread structure, and the piston head stop position adjustment unit rotates the piston rod and the piston base relative to each other using the driving force of the second actuator, thereby changing the position of the piston rod back and forth relative to the piston base.

4. The needle-free syringe or needle-free injection system according to claim 3, wherein a spur gear having a plurality of teeth extending linearly in the front-to-rear direction is formed on the outer periphery of a portion of the piston rod, and the piston head stop position adjustment unit has a cylindrical internal gear that is slidable back and forth relative to the spur gear and has a plurality of teeth on its inner periphery that extend linearly in the front-to-rear direction, so that the rotational driving force of the second actuator can be transmitted to the spur gear via the internal gear to rotate the piston rod, regardless of the position of the piston rod sliding back and forth.

5. The needle-free syringe or needle-free injection system according to claim 1 or 2, wherein the elastic body energy storage unit has a cam that can convert the rotational movement of the first actuator into forward and backward movement of the piston, the cam is provided so as to be rotatable around an axis along which the piston slides, and the cam has a shape such that the forward and backward thickness of the part of the cam that abuts against the piston changes with the rotation of the cam, thereby converting the rotational movement of the first actuator into forward and backward movement of the piston to store energy in the elastic body.

6. The needle-free syringe or needle-free injection system according to claim 5, characterized in that the cam has a portion in which the thickness of the portion in contact with the piston in the front-to-rear direction gradually increases as the cam rotates, thereby enabling the elastic body to store energy, and a portion in which the thickness of the portion in contact with the piston has a stepped shape in which the thickness suddenly decreases as the cam rotates, thereby enabling the elastic body to release energy.

7. The needle-free syringe or needle-free injection system according to claim 1 or 2, further comprising: a piston rod position sensor capable of detecting the position of the piston rod in the forward / backward direction and transmitting the detection result to a control unit; or a piston base position sensor capable of detecting the position of the piston base in the forward / backward direction and transmitting the detection result to a control unit.

8. A needle-free syringe or needle-free injection system according to claim 1 or 2, further comprising: a vacuum attachment having a cylindrical shape with two open ends, one open end of which can be attached to the plunger or the front of the machine body to which the plunger is attached, and the other open end of which can be brought into contact with the skin; and an aspirator that can suck air from within the vacuum attachment, thereby bringing the skin into close contact with the attachment.

9. A method for driving a needleless syringe or needleless injection system having a machine case main body to the front of which an ampoule having a plunger for pushing out the injection liquid therein can be attached, a piston provided on the machine case main body so as to be slidable back and forth, and an elastic body that applies a forward force to the piston, and which can inject the injection liquid in the ampoule by pressing the plunger with the piston head of the piston by releasing the stored elastic body and driving the piston forward, comprising: A) a step of storing the elastic body using an elastic body storing unit that stores the elastic body by moving the piston backward, and a first actuator that drives the elastic body storing unit; B) a step of changing the piston head stop position to a position in the forward direction using a piston head stop position adjustment unit that adjusts the piston head stop position at which the piston head stops when the stored elastic body is released and the piston is driven forward, and a second actuator that drives the piston head stop position adjustment unit; C) driving the piston forward by releasing the elastic body, thereby pressing the plunger with the piston head of the piston, and injecting the injection liquid in the ampoule.

10. The method for driving a needle-free syringe or needle-free injection system according to claim 9, wherein in step B, the distance by which the piston head stopping position is moved forward is controlled by controlling the drive amount of the second actuator in accordance with the number of injections of the injection liquid or the amount of injection liquid per injection set by the user.

11. The method for operating a needle-free syringe or a needle-free injection system according to claim 9, wherein step A) and step B) are carried out simultaneously.

12. The method for driving a needle-free syringe or needle-free injection system according to claim 9 or 11, wherein in step B, a piston rod position sensor is used to detect the position of the piston rod in the forward and backward directions, and when it is detected that the position of the piston rod has moved forward beyond a predetermined position, driving of the second actuator is stopped.

13. A method for operating a needle-free syringe or a needle-free injection system according to claim 9 or 11, characterized in that steps A) to C) are carried out immediately before the injection of the injection liquid.

14. A control program causing the control unit of the needle-free syringe or needle-free injection system of claim 1 to execute information processing including: A') generating a command signal to drive the first actuator a predetermined amount in order to energize the elastic body; B') generating a command signal to drive the second actuator a predetermined amount in order to change the piston head stop position to a position in the forward direction; and C') generating a command signal to release the energy stored in the elastic body in order to release the energy of the elastic body.

15. The control program according to claim 14, further comprising causing the control unit to execute information processing to determine the predetermined amount by which the second actuator is driven in step B') based on the number of injections of the injection liquid or the amount of injection liquid per injection set by the user.

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