Patent Description:
As a method of parenteral administration of therapeutic drugs in a patient's body, various drug delivery methods have been applied since ancient times. The most commonly used method for such a drug delivery system is a method using syringes. However, syringes have been feared by patients due to pain during injection, and have inevitable problems such as fear of infection due to wounds.

To solve this problem, drug delivery methods such as needleless syringes are being developed, and as a part of this research, drug delivery methods in which a drug is injected rapidly using a microjet method and penetrated directly into the body through the epidermis of skin are proposed.

For the high speed injection of such a microjet method, it is necessary to precisely and strongly inject a drug to the outside (i.e., skin). Such injection methods have been developed in various ways since the <NUM>, and recently, various injection methods such as an injection method using a piezoelectric ceramic element, an injection method through a shock wave caused by applying a laser beam to an aluminum foil, and an injection method using a Lorentz force have been developed. In addition, unlike conventional microjet injection, a laser-bubble microjet injection method capable of continuously injecting and reusing while finely controlling the amount of drug to be injected and the injection speed of a drug (i.e., a penetration depth of the drug).

The laser-bubble microjet injection method applies a phenomenon that bubbles are generated by the collapse of a liquid structure when a strong energy such as a laser beam is concentrated in a liquid in a closed chamber. As the bubbles are generated and grown in the liquid in the closed space as described above, the total volume increases, and thus, an elastic membrane forming one side of the chamber is rapidly extended to the outside to push a drug solution out of a nozzle, thereby causing microjet injection.

However, there is a problem in that external air is introduced through the nozzle from which a drug is injected after the injection of the drug to contaminate the remaining drug.

<CIT> discloses a microjet drug delivery system.

<CIT> discloses a needleless drug delivery system. In the document the needleless drug delivery system is described to enhance durability of a membrane that partitions a space to fill a drug by reinforcing a weak portion of the membrane or by forming a double membrane.

<CIT> relates to static pressure and a metering pump, the pump having a hollow interior and allowing a fluid to flow only in one direction, in which when pressure is applied to the pump, the internal volume decreases and a positive pressure is generated, and when the pressure is removed, the internal volume increases due to the elastic restoring power of the pump and a negative pressure is generated.

<CIT> discloses a method for making a jet injection drug delivery device wherein the drug delivery device has at least one drug reservoir and at least one injection nozzle. In the document the method is described to include identifying a drug desired to be delivered, identifying a volume of the drug desired to be delivered, establishing a reservoir diameter for the at least one drug reservoir, establishing a nozzle diameter for the at least one injection nozzle, identifying a tissue model for delivery of the drug, identifying a penetration depth in the tissue model for the delivery of the drug, and injecting the drug into the tissue model under variable pressure until the desired penetration depth is achieved.

<CIT> discloses a needle-less injector. In the document the needle-less injector is described to comprise a housing containing the liquid medication, a driver that forces the medication out of the orifice of the injection end of the housing at a sufficient speed to deliver the medication to the skin of the patient, and an at least partially external resistance sensitive trigger operatively coupled to the driver and the trigger portion of the housing.

<CIT> discloses a transdermal drug delivery system for delivering medication through the skin. In the document a microjet drug delivery system is described to comprise a pressure chamber which has a predetermined accommodating space and which has a sealed interior sealingly filled with water serving as a liquid for generating pressure, a drug chamber which is arranged in the vicinity of the pressure chamber so as to accommodate a drug solution in a predetermined accommodating space thereof, and which has, on one side thereof, a micronozzle for jetting the drug solution to the outside in mircojets, an elastic membrane interposed between the pressure chamber and the micro-drug chamber, and a laser unit for emitting a laser beam onto the liquid for generating pressure stored in the pressure chamber so as to generate bubbles in the liquid in order to generate pressure.

<CIT> discloses an ejection apparatus for the high pressure ejection of a liquid. In the document the apparatus is described to include (a) a pressure chamber for containing the liquid, (b) an ejection opening communicating between an outside and an inside of the pressure chamber, (c) a working piston displaceable in the pressure chamber from a first position at a beginning of a working stroke to second position at an end of the working stroke, and (d) a drive for driving the working piston.

Document D8 (<CIT>) discloses a sealed delivery system for dispensing metered volumes of a pure or sterile flowable substance. In the document a handheld sealed delivery system is described to comprise a continuously sealing one-way valve assembly at a distal end, and a volume reducing reservoir at a proximal end, wherein the pure or sterile flowable substance can be stored in the volume reducing reservoir. In operation, a user pushes down upon a push button driven actuator assembly, acting upon a metering pumping chamber, which is in fluid communication with the pure or sterile flowable substance stored in the volume reducing reservoir via a check valve. Depression of the push button driven actuator causes a dispensing pump to push a metered volume of flowable substance through the continuously sealing one way dispensing valve assembly.

<CIT> discloses an injector without a needle for injecting drug using an epidermal layer of animal, and an amount of the drug to scan from a medicine case is inhaled to the inside of a scanner with an operation of repetitively pulling a lever and the drug within the scanner is automatically scanned with the operation of pulling the trigger.

The present invention is directed to a microjet drug injection device equipped with a backflow prevention valve for preventing external air from entering a lower housing through an injection nozzle and for automatically supplying a drug by providing a backflow prevention valve on the side of the lower housing to which a drug is filled to move fluid in one direction.

The objects of the one or more embodiments are not limited to the following description, and it should be understood by one of ordinary skill in the art that other objects not described here may be clearly understood from the following descriptions.

Advantageous embodiments are subject of the dependent claims.

According to an aspect of the present invention, a drug injection device is equipped with a backflow prevention valve, the drug injection device comprises an upper housing sealed at one side of a pressure partition formed to surround the side and providing a floodlight lens at the sealed side; a lower housing comprising a drug partition formed to surround a side surface and an injection nozzle extending from the drug partition and comprising an injection path of drugs formed at a lower portion of the injection nozzle , wherein the lower housing is connected to or is extended from the upper housing; a compartment provided between the upper housing and the lower housing and partitioning a space in which a pressure generating liquid is filled in the upper housing and a space in which a drug is filled in the lower housing, and transmitting pressure acting on the space filled with the pressure generating liquid to the space in which a drug is filled; and a backflow prevention valve formed of an elastic material, wherein an upper side is provided in a lower side in the lower housing to be in close contact with the lower housing, an open circular inlet is formed on the upper side and the shape of the cross section, as the cross section goes downward, becomes gradually narrower as it changes from circular to linear, a lower end of the backflow prevention valve is formed with a slit through which a drug passes, allowing fluid to move only toward the injection nozzle, a pressure generating liquid is filled and sealed in a space on the side of the floodlight lens, and a drug filled in the space on the side of an injection nozzle is injected to the injection nozzle by pressure due to expansion of the pressure generating liquid.

According to an example embodiment the backflow prevention valve is provided with a lower end cross-section and a slit shaped "C".

According to an example embodiment, in a lower portion of the backflow prevention valve, an inner material of the "C" shape has lower elastic modulus than an outer material of the "C" shape.

According to an example embodiment, the backflow prevention valve is provided with a lower end cross-section and a slit shaped "+".

According to an example embodiment, the microjet drug injection device comprises a plurality of injection paths.

According to an example embodiment, the injection paths are provided in a regular polygonal arrangement.

According to an example embodiment, an inner wall forming the injection path is formed of a ceramic material.

According to an example embodiment, diameter of the injection path is <NUM> micrometers to <NUM> micrometers.

According to a drug injection device equipped with a backflow prevention valve of an embodiment of the present invention, external air may be prevented from flowing into a lower housing through an injection nozzle, and a drug may be automatically supplied after drug injection by providing a backflow prevention valve in a lower side of the lower housing to move fluid in one direction.

In addition, the shape of a lower end cross-section and a slit of the backflow prevention valve may be "C" shaped, whereby a sealing force may be increased and durability may be increased as compared with a case where the cross-section and the slit are straight.

In addition, since an inner material of the "C" shape of the backflow prevention valve is made of a material whose elastic modulus is less than that of an outer material, the slit may be opened more easily.

In addition, the shape of the lower end cross-section and the slit of the backflow prevention valve may be "+" shaped, whereby a sealing force may be increased and durability may be increased as compared with the case where the cross-section and the slit are straight. Also, the slit may be located close to an injection path and a drug may be pushed out at more uniform pressure.

In addition, by providing a plurality of injection paths, a procedure time may be shortened when multiple injections are required in an affected area.

In addition, by arranging the injection paths in a regular polygonal arrangement, drugs may be injected into the body at equal intervals.

In addition, by forming an inner wall of the injection path with a ceramic material, it is possible to improve durability by preventing the end of the injection path from being broken or deformed during the microjet injection.

In addition, by setting a diameter of the injection path to <NUM> to <NUM> micrometers, it is possible to minimize drug bounce off the surface of the skin while maintaining a sufficient skin injection depth of a drug.

Since the present invention may have diverse modified embodiments, preferred embodiments are illustrated in the drawings and are described in the detailed description. However, this does not limit the present invention within specific embodiments and it should be understood that the present invention covers all the modifications, equivalents, and replacements within the idea and technical scope of the present invention.

Further, if it is described that one element is "connected" or "accesses" the other element, it is understood that the one element may be directly connected to or may directly access the other element but unless explicitly described to the contrary, another element may be "connected" or "access" between the elements.

However, if it is described that one element is "directly connected" or "directly accesses" the other element, it is understood that there are no other elements exists between them.

The terms used in this application, only certain embodiments have been used to describe, is not intended to limit the present invention. It will be further understood that the terms "comprises" and/or "comprising" when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments belong.

Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings, but should be construed as meanings and concept consistent with the inventive concept based on the principle that the inventor can properly define the concept of terms in order to explain his or her invention in the best way. In addition, if there is no other definition in the technical terms and scientific terms used, it can be seen that they have a meaning that can be commonly understood by one of ordinary skill in the art. In the following description and the accompanying drawings, descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted. The drawings introduced below are provided by way of example so as to fully convey the present invention to one of ordinary skill in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms. Also, like reference numerals refer to like elements throughout the specification. It should be noted that the same elements in the drawings are denoted by the same numerals wherever possible.

<FIG> is a view of an exploded concept of a microjet drug injection device equipped with a backflow prevention valve, according to an embodiment of the present invention. <FIG> is a view of a concept of assembling the microjet drug injection device of <FIG>. <FIG> is a view of a concept in which a pressure generating liquid is filled in the microjet drug injection device of <FIG>. <FIG> are plan views from below of each embodiment of a backflow prevention valve of <FIG>. <FIG> is a plan view from below of an injection nozzle of <FIG>. <FIG> is a view of a concept in which an energy intensive device is added to <FIG>. <FIG> is a view of a concept in which a drug supply unit is added to <FIG>.

As illustrated in <FIG>, the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention includes an upper housing <NUM> equipped with a floodlight lens <NUM>, a lower housing <NUM>, a compartment <NUM>, and a backflow prevention valve <NUM>, wherein a pressure generating liquid <NUM> is filled and sealed in a space on the side of the floodlight lens <NUM>, and a drug filled in a space on the side of an injection nozzle <NUM> is injected to the injection nozzle <NUM> by pressure due to expansion of the pressure generating liquid <NUM>.

The upper housing <NUM> is sealed at one side (upper side) of the pressure partition <NUM> formed to surround a side surface, and the floodlight lens <NUM> is provided at the sealed side.

The upper housing <NUM> is to form a closed space in which the pressure generating liquid <NUM> is filled, and forms a closed space in which the pressure generating liquid <NUM> is filled by blocking a side by the pressure partition <NUM>, by blocking one side (the upper side in <FIG>) provided with the floodlight lens <NUM>, and by blocking the other side by the partition <NUM> to be described later below.

<FIG> show an example in which the floodlight lens <NUM> is expressed in a convex shape and blocks a portion of one side of the pressure partition <NUM>, but the present invention is not limited thereto. As long as the light transmitting is possible, the floodlight lens <NUM> may have various shapes such as a planar shape and a concave shape. It is also possible to block the whole of one side of the pressure partition <NUM> with only the floodlight lens <NUM>.

Normal water may be used as the pressure generating liquid <NUM>, and various liquid materials such as polymer sol and gel such as alcohol or polyethylene glycol may be used. In addition, a degassed liquid may be preferably used as the pressure generating liquid <NUM> in order to minimize residual bubbles in generating bubbles. In addition, when an electrolyte (salt, etc.) is added to the pure water as the pressure generating liquid <NUM>, molecules are ionized to reduce the energy required for the collapse of a molecular structure of a liquid, which is more preferable because bubbles may be formed with better efficiency.

The lower housing <NUM> includes a drug partition <NUM> formed to surround a side surface of the lower housing <NUM> and the injection nozzle <NUM> extending from the drug partition <NUM> and including an injection path <NUM> of drugs formed at a lower portion of the injection nozzle <NUM>. The lower housing <NUM> is connected to or extended with the upper housing <NUM>.

The lower housing <NUM> is for forming a space in which a drug is filled, and the drug partition <NUM>, the injection nozzle <NUM>, and the compartment <NUM> block other portions except the injection path <NUM> of drugs to form a space in which a drug is filled.

Here, the injection nozzle <NUM> refers to a portion in which the injection path <NUM> of drugs is formed, and may be all or a part of the inclined portion shown in <FIG>.

In this case, the upper housing <NUM> and the lower housing <NUM> may be integrally formed, or may be formed to be separated and coupled.

In addition, the injection nozzle <NUM> may be provided to be detachable to the lower housing <NUM>. When the injection nozzle <NUM> is provided detachably to the lower housing <NUM>, when the injection nozzle <NUM> is broken, contaminated, or clogged, it can be solved simply by replacing only the injection nozzle <NUM> without replacing the entire lower housing <NUM>, which is advantageous in terms of cost.

Materials of a lower portion and a side portion of the lower housing <NUM> including the injection nozzle <NUM> may be variously selected as long as there is no problem in achieving the functions of the present invention, such as stellite, an aluminum alloy, and a zirconium-based ceramic material. Only a part of the lower portion of the lower housing <NUM> in which the injection path <NUM> is formed may be made of the zirconium-based ceramic material through insert injection.

Among zirconium-based ceramic materials, zirconium oxide (zirconia) has low thermal conductivity, which prevents the deterioration of a drug due to heat transfer during laser irradiation, and has high burst toughness and very high resistance to crack propagation, and thus it is possible to prevent a phenomenon in which ends of the injection path <NUM> and the like are damaged or deformed during microjet injection. Therefore, preferably, the lower housing <NUM>, the injection nozzle <NUM>, or the injection path <NUM> is formed of zirconium oxide (zirconia) in zirconium-based ceramic materials.

In addition, the lower housing <NUM> or the inside of the injection nozzle <NUM> has a larger horizontal cross-sectional area toward the upper side in some or all sections, and may include a plurality of sections in which inclination of an inner wall is constant for each predetermined section, but the inclination of the inner wall decreases toward the upper direction.

In addition, the lower housing <NUM> or the inside of the injection nozzle <NUM> may be provided in a trumpet shape that extends in a curved shape toward the compartment <NUM> from the injection path <NUM> in some or all sections.

The lower housing <NUM> or the inside of the injection nozzle <NUM> may further concentrate on pushing a drug into the injection path <NUM> by pressure transmitted from the compartment <NUM>. Accordingly, the drug injected into the injection path <NUM> may obtain a larger injection speed.

The compartment <NUM> is provided between the upper housing <NUM> and the lower housing <NUM> and partitions a space in which a pressure generating liquid is filled of the upper housing <NUM> and a space in which a drug is filled of the lower housing <NUM>, and transmits pressure acting on the space filled with the pressure generating liquid to the space in which a drug is filled.

That is, the compartment <NUM> partitions the upper housing <NUM> and the lower housing <NUM> to form a closed space in which the pressure generating liquid <NUM> is filled on one side of the compartment <NUM> (upper side of the compartment <NUM> of <FIG>).

When the upper housing <NUM> and the lower housing <NUM> are formed to be separated and coupled, the compartment <NUM> is preferably interposed in a portion where the upper housing <NUM> and the lower housing <NUM> are connected to each other (see <FIG>).

The compartment <NUM> may be provided between the upper housing <NUM> and the lower housing <NUM>, and may be formed of an elastic material that partitions the upper housing <NUM> and the lower housing <NUM>.

In this case, the compartment <NUM> may be made of silicon rubber or the like.

The compartment <NUM> may be damaged first around the edge and the center due to rapid expansion. Therefore, the partition <NUM> preferably reinforces the edge and the center in preparation for rapid expansion.

In the above, the compartment <NUM> is a film formed of an elastic material, but the present invention is not limited thereto. If a plate-shaped disk is configured in the form of reciprocating up and down and may transmit the pressure acting on the space filled with the pressure generating liquid to the space in which a drug is filled, various implementations are possible.

The backflow prevention valve <NUM> is formed of an elastic (rubber) material, wherein the upper side is provided in a lower side of the lower housing <NUM> to be in close contact with the lower housing <NUM>, and an open circular inlet is formed on the upper side and the shape of the cross section, as the cross section goes downward, becomes gradually narrower as it changes from circular to linear. A lower end of the backflow prevention valve <NUM> is formed with a slit through which a drug passes, allowing fluid to move only toward the injection nozzle <NUM>.

The backflow prevention valve <NUM> allows the flow of fluid (liquid, gas, etc.) to flow in only one direction, and may be partially or entirely formed in a shape in which an entrance is closed like a duck's beak or a flute spout.

In addition, the backflow prevention valve <NUM>, by allowing the drug filled in the lower housing <NUM> to be injected to the outside through the injection path <NUM> but preventing external air from being introduced through the injection path <NUM>, may prevent the drug from being contaminated by preventing the external air from being mixed with the drug filled in the lower housing <NUM>.

In more detail, the slit of the backflow prevention valve <NUM> is normally kept closed. The slit remains closed while a drug is filled in the lower housing <NUM>. Subsequently, when the compartment <NUM> transmits the pressure to the side filled with a drug by the expansion of the pressure generating liquid <NUM>, the slit is opened and the drug is injected through the injection path <NUM> by the pressure. In addition, when the pressure in the side filled with a drug is lowered and the injection of the drug is completed, the slit is closed by a restoring force (elastic force) of the backflow prevention valve <NUM> to prevent fluid from being sucked from the outside.

In this case, a linear shape in which the slit is closed may be applied to a straight line (see <FIG>), a curve (see <FIG>), an intersection line (see <FIG>), etc..

As shown in <FIG>, the backflow prevention valve <NUM> of the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention may be characterized in that the lower end cross-section and the slit are "C" shaped.

When the lower end cross-section and the slit are "C" shaped, a sealing force may be increased so that the slit does not normally open as compared with the case where the cross-section and the slit are straight.

In addition, when the shape of the lower end cross-section and the slit are "C" shape, durability may be increased to increase the period of time that the slit does not normally open even if the slit is used continuously for a longer time as compared with the case where the shape of the cross section and the slit is a straight shape.

At this time, the lower portion of the backflow prevention valve <NUM> may be characterized in that an inner material of the "C" shape has lower elastic modulus than an outer material of the "C" shape.

This is to allow the slit of the backflow prevention valve <NUM> to be more easily opened by pressure caused by the expansion of the pressure generating liquid <NUM>.

At this time, the ratio of elastic modulus of the inner material of the "C" shape and the outer material of the "C" shape is preferably about <NUM> to about <NUM>: <NUM>.

As shown in <FIG>, the backflow prevention valve <NUM> of the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention may be characterized in that the lower end cross-section and the slit are "+" shaped.

When the lower end cross-section and the slit are "+" shaped, a sealing force may be increased so that the slit does not normally open as compared with the case where the cross-section and the slit are straight. In addition, the center of the slit may be on the extension line of the injection path <NUM> to minimize the maximum length of the slit so that the slit may be located near the injection path <NUM>.

In addition, even when using the injection nozzle <NUM> provided with a plurality of injection paths <NUM> to be described later below, the injection nozzle <NUM> may push a drug at a more uniform pressure to each injection path <NUM>.

Also, when the lower end cross-section and the slit are "+" shaped, durability may be increased to increase the period of time that the slit does not normally open even if the slit is used continuously for a longer time as compared with the case where the shape of the cross section and the slit is a straight shape.

The injection path <NUM> of the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention may be plural.

The plurality of injection paths <NUM> may be provided in the lower portion of the lower housing <NUM>. That is, only one injection path <NUM> may be provided, but two or more injection paths <NUM> may also be provided.

The number of injection paths <NUM> may be preferably <NUM> to <NUM>.

In addition, an upper portion of each of the injection paths <NUM> may be formed in a tapered shape in which a horizontal cross-sectional area becomes narrower from the upper side to the lower side.

The microjet drug injection device provided with a backflow prevention valve according to an embodiment of the present invention having the plurality of injection paths <NUM> as described above is highly desirable because the microjet drug injection device may shorten a procedure time by injecting a drug into a wide area by a single microjet injection when several injections are required in a wide area.

As illustrated in <FIG>, the injection paths <NUM> of the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention may be provided in a regular polygonal arrangement.

The plurality of injection paths <NUM> may be provided in a regular polygonal arrangement such that the distance between neighboring injection paths <NUM> is constant, and thus drugs may be injected into the body at equal intervals during microjet injection.

Although <FIG> illustrates an example in which four injection paths <NUM> are provided in a square arrangement, the present invention is not limited thereto, and various embodiments such as rhombus forms are possible if the injection is possible at equal intervals.

An inner wall forming the injection path <NUM> of the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention may be formed of a zirconium-based ceramic material (zirconia).

The inner wall forming the injection path <NUM> may be formed of a zirconium-based ceramic material and is preferably formed of zirconium oxide (zirconia). This is because, as mentioned above, zirconium oxide has high burst toughness and very high resistance to crack propagation, thereby preventing the end of the injection path <NUM> from being broken or deformed during the microjet injection.

The injection nozzle <NUM> formed of the zirconium-based ceramic material is provided to be detachable from the lower housing <NUM>, and thus when the injection nozzle <NUM> provided with the injection path <NUM> is broken or when a change in the diameter of the injection path <NUM> is required, the injection nozzle <NUM> may be separated from the lower housing <NUM> so as to be replaced.

A diameter of the injection path <NUM> of the microjet drug injection device equipped with a backflow prevention valve according to an embodiment of the present invention may be <NUM> micrometers to <NUM> micrometers.

When the diameter of the injection path <NUM> is less than <NUM> micrometers, the amount of drug to be injected is small and the drug is not injected into the body to a sufficient depth. When the diameter of the injection path <NUM> exceeds <NUM> micrometers, the diameter of a microjet to which the drug is injected may increase, thereby increasing the amount of drug that is bounced off the surface of the skin and increasing the waste of the drug.

In addition, when the injection path <NUM> of drugs is formed to a diameter of <NUM> or less, even if a drug is filled in a space to be filled with a drug, if no pressure is applied above a certain level, the drug cannot escape through the injection path <NUM> of drugs.

As illustrated in <FIG>, the microjet drug injection device provided with a backflow prevention valve according to an embodiment of the present invention may further include the energy intensive device <NUM> that concentrates energy toward a specific point in a closed space filled with the pressure generating liquid <NUM>.

The energy intensive device <NUM> refers to a device capable of concentrating energy using a microwave, a laser beam, or the like.

That is, the energy concentrator <NUM> concentrates energy such as a laser beam in the pressure generating liquid <NUM> to push a drug into the injection path <NUM> of drugs by instantaneous volume expansion (pressure increase) due to evaporation of the pressure generating liquid <NUM> and delivery of shock waves, thereby generating a microjet.

As illustrated in <FIG>, the microjet drug injection device provided with a backflow prevention valve according to an embodiment of the present invention may further include the drug supply unit <NUM> provided with the drug supplement <NUM> through which the drug partition <NUM> is formed to form a drug supply path and connected to the drug supplement <NUM> to supply a drug to a space on the side of the lower housing <NUM> through the drug supplement <NUM>.

In other words, the drug supply unit <NUM> connected to the drug supplement <NUM> may be used to replenish a drug to the space to be filled with a drug.

The drug supply unit <NUM> may replenish a drug at a certain pressure at which a drug does not exit the injection path <NUM> of drugs.

This is to ensure that a drug is always filled without any control.

In other words, if there is no drug in a space to be filled with a drug, a drug is filled. However, if there is a drug in the space to be filled with a drug, a drug may be filled at a level that does not push the drug from the injection path <NUM> of drugs.

To describe the order in which a drug is replenished and injected, a drug is introduced into the lower housing <NUM> from the drug supply unit <NUM> through the drug supplement <NUM>, and the drug in the lower housing <NUM> may be discharged to the outside through the injection path <NUM> to be injected in the form of a microjet. After the drug is injected, while the inflow of fluid to the injection path <NUM> is blocked by the backflow prevention valve <NUM>, a drug may be refilled by a reduced pressure as the drug is injected.

By this circulation process, a drug may be automatically charged without a separate power supply or separate control.

In this case, all or a part of the inside of the lower housing <NUM> or the injection nozzle <NUM> may be formed in a tapered shape in which a horizontal cross-sectional area decreases from the compartment <NUM> toward the injection path <NUM>. Through this, a pressure of the compartment <NUM> is concentrated in the injection path <NUM> to increase the injection speed of a microjet.

The present invention is not limited to the above-described embodiments and the scope of application is various, and various modifications may be made without departing from the subject matter of the present invention as claimed in the claims.

Claim 1:
A drug injection device equipped with a backflow prevention valve, the drug injection device comprising:
an upper housing (<NUM>) in which at least one surface is sealed by a pressure partition (<NUM>) and providing a floodlight lens (<NUM>) at the sealed surface;
a lower housing (<NUM>), in which at least one surface is sealed by a drug partition (<NUM>), comprising an injection nozzle (<NUM>) having an injection path formed at a lower portion;
a compartment (<NUM>) provided between the upper housing (<NUM>) and the lower housing (<NUM>) to partition a space filled with a liquid for generating pressure at the upper housing (<NUM>) and a space filled with a drug at the lower housing (<NUM>);
a backflow prevention valve (<NUM>) provided with a slit through which the drug passes at a lower end and allowing the drug to move only toward the injection nozzle (<NUM>), and
a drug supplement (<NUM>) formed through the drug partition (<NUM>), and the drug is supplied to a space on the side of the lower housing through the drug supplement (<NUM>);
wherein, when the compartment (<NUM>) transmits pressure to the space filled with the drug by expansion of the liquid for generating pressure, the slit opens and the drug is injected through the injection nozzle (<NUM>), and
when the pressure in the space filled with the drug is lowered, the slit is closed by a restoring force of the backflow prevention valve (<NUM>), so that fluid is prevented from being sucked from the outside,
wherein the backflow prevention valve (<NUM>) comprises an elastic material, and the slit of the backflow prevention valve (<NUM>) remains closed while the drug is filled inside the lower housing, and wherein an upper side of the backflow prevention valve (<NUM>) is provided in a lower side of the lower housing (<NUM>) to be in close contact with the lower housing (<NUM>), and the backflow prevention valve (<NUM>) has an open circular inlet on an upper side, and the cross section of the backflow prevention valve (<NUM>) becomes narrower toward a lower side to form a linear shape.