A control method of a water-light injection device handle

Abstract

The application belongs to the technical field of medical apparatus and discloses a control method of a handle of a water-light injection instrument, which comprises four steps of rough pushing emptying, fine pushing injection, pressure relief resetting and liquid supplementing positioning. In the rough pushing emptying step, a control unit controls a stepping motor to drive a pushing rod forward in one direction, and the liquid medicine in a medicine cavity is extruded forward until a continuous liquid drop is formed at a needle tip and then locked; in the fine pushing injection step, an incremental driving voltage is applied to a piezoelectric ceramic displacement block to make it linearly elongate, and the pushing rod pushes the liquid medicine out of the needle tip; in the pressure relief resetting step, the voltage is removed to make the piezoelectric ceramic displacement block contract and reset, and the pushing rod retreats to release residual pressure; and in the liquid supplementing positioning step, the stepping motor is controlled to advance forward in one direction to make up for the consumed liquid medicine. The application cooperatively controls the one-way advancement of the stepping motor and the accurate extension and contraction of the piezoelectric ceramic displacement block throughout the whole process, eliminates the accumulated error and liquid medicine waste, and improves the injection precision.

Description

Technical Field

[0001] This invention relates to the field of medical devices, specifically to a control method for the handle of a water-light injection device. Background Technology

[0002] A water-light injection device is a beauty device that uses negative pressure to attract the skin and then uses microneedles to precisely inject nutrients such as hyaluronic acid, vitamins, and collagen into the dermis. It can effectively solve problems such as dry skin, peeling, and dullness, making the skin hydrated and radiant.

[0003] Existing composite-driven water-light injection device handles, such as the nine-hole negative pressure injection needle disclosed in Chinese patent document CN111420182A, have a structure including a nine-needle Luer connector, a nine-needle needle seat, a nine-needle shell, and nine needle tubes. The liquid medicine enters the flow channel system inside the needle seat from the syringe through the Luer connector and is then distributed to each needle tube.

[0004] However, in actual injection processes, this type of structure has the following technical deficiencies in terms of control: Current mesotherapy injection devices typically use a stepper motor to drive a lead screw to push the injection rod for injection. However, a key challenge arises during mesotherapy injection: the injection pressure is high. If forward injection is continued, the medication will continuously leak or spray out at the needle tip due to the high pressure, leading to inaccurate dosage and medication waste. Therefore, a "push a few steps, retreat half a step" control strategy is often adopted in practice. That is, after the injection rod advances a few steps to complete the injection, it retreats half a step to release the pressure and release the residual pressure inside the syringe. Although this frequent forward and reverse operation alleviates the high-pressure leakage problem, it introduces new drawbacks: the lead screw thread clearance is repeatedly crossed during each reversal, and the stepper motor also experiences step loss. Long-term operation leads to the continuous accumulation of errors, eventually causing the actual injection dose to deviate significantly from the set dose. At the same time, the medication released during each "half step back" is also wasted, further exacerbating medication loss.

[0005] To address the technical problems mentioned above, such as insufficient injection accuracy, cumulative errors caused by frequent reversals, and waste of medication due to pressure relief during reversals, a control method for the handle of a water-light injection device is urgently needed. Summary of the Invention

[0006] The purpose of this invention is to provide a control method for the handle of a water-light injection device, which aims to solve the technical problems in the prior art, such as the cumulative error and waste of medicine caused by the frequent reversal of the stepper motor due to the 'push a few steps and retreat half a step' control strategy, and the insufficient injection accuracy when relying solely on stepper motor drive.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A control method for a mesotherapy injection device handle includes the mesotherapy injection device handle: the mesotherapy injection device handle includes a housing, a stepper motor, a transmission mechanism, an injection rod, a drug cavity, a needle, and a control unit. The stepper motor is fixedly installed in the housing and connected to the injection rod through the transmission mechanism. One end of the drug cavity is an open end for inserting the injection rod, and the other end is a bottom wall. The needle is fixed to the outer surface of the bottom wall, and the needle inlet opens directly into the inner surface of the bottom wall. The injection rod is slidably disposed in the drug cavity along the axial direction. A piezoelectric ceramic displacement block is provided between the injection rod and the transmission mechanism. The control unit is electrically connected to the stepper motor and the piezoelectric ceramic displacement block respectively. The control method includes the following steps: Coarse push emptying step: The control unit controls the stepper motor to drive the injection rod forward in one direction, squeezing the liquid medicine in the drug cavity forward until continuous droplets are formed at the tip of the needle, then controls the stepper motor to stop and lock. Precision injection step: The control unit applies an increasing driving voltage to the piezoelectric ceramic displacement block, causing it to produce a micron-level linear elongation displacement, which pushes the injection rod to discharge the drug from the needle tip; Pressure relief and reset steps: The control unit cancels the driving voltage of the piezoelectric ceramic displacement block, causing it to contract and reset, thereby driving the injection rod to retract and release the residual pressure inside the drug cavity; Fluid replenishment positioning step: The control unit converts the preset single injection volume into the number of drive steps of the stepper motor, controls the stepper motor to advance the corresponding stroke, so that the injection rod returns to the fluid replenishment positioning position, and then repeats the above fine injection step and pressure relief reset step.

[0008] Preferably, the control unit applies driving voltage to the piezoelectric ceramic displacement block in segments using a progressive pulse method, with a pause between adjacent voltage applications.

[0009] Preferably, the stepper motor moves forward in one direction throughout the entire injection process without switching between forward and reverse directions.

[0010] Preferably, the linear elongation displacement of the piezoelectric ceramic displacement block is from 1 μm to 100 μm.

[0011] Preferably, the drug cavity is an integral shell, which has N independent sub-cavities separated by partitions, where N≥2. The front bottom wall of each sub-cavity corresponds to and is directly connected to the internal channel inlet of each needle tube. Each injection rod is respectively disposed in each sub-cavity. The rear end of each injection rod is fixedly connected by an integral linkage block. The transmission mechanism is connected to the integral linkage block through the piezoelectric ceramic displacement block. The control unit synchronously drives each injection rod to perform the coarse injection and emptying step, the fine injection step, the pressure relief and reset step, and the fluid replenishment and positioning step through the integral linkage block.

[0012] Preferably, N=9, and the nine needles are arranged in a ring or matrix.

[0013] Preferably, each sub-cavity is independently filled with the same or different formulations of medicine. When the control unit synchronously drives each injection rod through the overall linkage block, each sub-cavity outputs an equal amount of medicine at the same time.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. The needle is directly fixed to the front end of the drug cavity, and the inlet of the needle tube opens directly at the bottom end of the conical funnel-shaped inner wall of the drug cavity. When the injection rod is pushed forward, the boss end face directly occupies the conical space, forcibly squeezing the liquid into the needle tube, which fundamentally eliminates the problem of dead space residue caused by additional flow channels and liquid storage chambers in the existing technology.

[0015] 2. A collaborative control strategy of "stepper motor-driven coarse pushing and positioning and liquid replenishment + piezoelectric ceramic-driven fine pushing injection" is adopted. The stepper motor is responsible for large-stroke mechanical movements, and the piezoelectric ceramic displacement block is responsible for high-precision injection. This takes into account both the requirements of stroke range and injection accuracy, and fundamentally eliminates the cumulative error and liquid waste caused by frequent reversals in the traditional "push a few steps and retreat half a step" scheme.

[0016] 3. The independent drug delivery of nine needles with multiple cavities, combined with the synchronous drive of the overall linkage block, enables differentiated drug delivery that cannot be achieved by the existing nine-needle diversion structure. Attached Figure Description

[0017] Figure 1 To illustrate the overall structure of Embodiment 1; Figure 2 A cross-sectional view showing the internal structure of Embodiment 1; Figure 3 A schematic diagram illustrating Example 2.

[0018] In the diagram: 1. Housing; 2. Stepper motor; 3. Transmission mechanism; 31. Fixing frame; 4. Injection rod; 41. Conical boss end face; 5. Drug cavity; 51. Bottom wall; 6. Needle; 7. Piezoelectric ceramic displacement block; 8. Overall linkage block. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Single-cavity single-pump structure Combination Figure 1 and Figure 2 The water-light injection device handle with a zero dead space structure provided in this embodiment mainly includes a housing 1, a stepper motor 2, a transmission mechanism 3, an injection rod 4, a drug cavity 5, and a needle 6.

[0021] The housing 1 serves as the handheld base, and a stepper motor 2 is fixedly installed inside it. The transmission mechanism 3 is preferably a lead screw and nut mechanism, which is positioned and installed inside the housing 1 by a fixing bracket 31, and the power input end of the transmission mechanism 3 is connected to the output shaft of the stepper motor 2.

[0022] The drug chamber 5 and the injection rod 4 are located outside the housing 1 (i.e., on the outer front end of the housing 1), and the drug chamber 5 is fixed relative to the housing 1. The inside of the drug chamber 5 forms a closed chamber for containing the drug solution to be injected. One end of the drug chamber 5 is an open end for the injection rod 4 to be inserted, and the other end is a bottom wall 51. The needle 6 is fixed to the outer surface of the bottom wall 51, and the inlet of the needle 6 opens directly on the inner surface of the bottom wall 51. This eliminates the need for a diversion channel and an intermediate liquid storage chamber in traditional structures, providing a basis for achieving zero dead space.

[0023] The injection rod 4 is slidably disposed axially within the drug cavity 5, with its rear end extending to the outside of the drug cavity 5. It is connected to the power output end of the transmission mechanism 3 (which extends to the outside of the housing 1) via a piezoelectric ceramic displacement block 7. The stepper motor 2 drives the injection rod 4 through the transmission mechanism 3 to perform large-stroke coarse injection for emptying and replenishing the liquid. After the stepper motor 2 is locked, the piezoelectric ceramic displacement block 7 drives the injection rod 4 through the inverse piezoelectric effect to perform micron-level fine injection. The two work together to complete the injection process.

[0024] The bottom wall 51 of the drug cavity 5 is not a planar structure; its inner wall surface is a conical funnel shape with its inner diameter gradually decreasing towards the needle tip 6. The conical space enclosed by this conical funnel-shaped inner wall is used to gather the liquid medicine and guide it to the inlet of the needle tip 6. The inlet of the needle tip 6 is directly opened at the bottom end of the conical funnel-shaped inner wall (i.e., the opening at the bottom of the funnel, which may have a rounded transition and does not need to be tapered to a point), so that the internal channel of the needle tip 6 is directly connected to the inside of the drug cavity 5, without any additional liquid storage chamber or diversion channel in between.

[0025] The front end of the injection rod 4 is provided with a conical boss end face 41 that matches the taper of the conical funnel-shaped inner wall. The outer conical surface of the conical boss end face 41 and the conical funnel-shaped inner wall of the bottom wall 51 are either interference fit or precision fit with a clearance of no more than 0.01mm.

[0026] As the injection rod 4 is advanced toward the drug cavity 5, the conical protrusion end face 41 gradually enters the conical space enclosed by the conical funnel-shaped inner wall. With the increase in advancement depth, the conical protrusion end face 41 gradually occupies the internal volume of the conical space, forcibly squeezing the liquid medicine present in the conical space and entering the needle 6 through the needle inlet opened at the bottom end, and finally exiting from the needle tip.

[0027] When the injection rod 4 is pushed to the limit position, the outer conical surface of the conical boss end face 41 is tightly fitted with the conical funnel-shaped inner wall of the bottom wall 51, forming a conical seal between the two. There is no remaining volume in the conical space, and the medicine is completely squeezed out, thereby achieving zero liquid residue.

[0028] The conical funnel-shaped structure also has a self-guiding function. When the injection rod 4 is pushed forward, the conical boss end face 41 can automatically center along the conical surface without the need for an additional guiding structure, thus simplifying the manufacturing process. To prevent hard wear, an elastic sealing gasket is provided on the outer conical surface of the conical boss end face 41.

[0029] The end face of the drug cavity 5 that contacts the skin may also be equipped with a baffle, through which the needle 6 passes and extends a predetermined length. The end face of the baffle adheres to the surface of the skin during injection, and the length of the needle 6 extending beyond the baffle is the maximum depth to which the needle 6 penetrates the skin. Preferably, the length of the needle 6 extending beyond the end face of the baffle is no more than 4 mm to ensure that the injection depth is controlled within the dermis.

[0030] A piezoelectric ceramic displacement block 7 is provided between the stepper motor 2 and the injection rod 4. The piezoelectric ceramic displacement block 7 is preferably a stacked piezoelectric ceramic.

[0031] The working principle of the piezoelectric ceramic displacement block 7 is as follows: when a voltage is applied, the piezoelectric ceramic material deforms based on the inverse piezoelectric effect. The deformation is precisely linearly related to the applied voltage, thereby achieving high-precision micro-displacement control. By precisely controlling the magnitude of the applied voltage, a displacement accuracy of 1μm to 100μm can be achieved.

[0032] The control unit is located inside the housing 1 and is electrically connected to the stepper motor 2 and the piezoelectric ceramic displacement block 7. The control unit is configured to adopt a collaborative control strategy of "stepper motor driving coarse pushing and liquid replenishment + piezoelectric ceramic driving fine pushing injection". That is, the stepper motor 2 is responsible for the large stroke mechanical action (coarse pushing and liquid replenishment positioning), and the piezoelectric ceramic displacement block 7 is responsible for the micron-level precision injection of the liquid. The two work together, and the stepper motor 2 moves in one direction throughout the entire process without the need for forward and reverse switching.

[0033] Based on the above-described single-cavity single-pump structure, a specific implementation of the control method is provided: Step 1: Coarse emptying: The control unit controls the stepper motor 2 to drive the injection rod 4 forward, squeezing the liquid medicine in the drug chamber 5 forward. The conical protrusion end face 41 has not yet entered the conical space; a space remains between the conical protrusion end face 41 and the conical funnel-shaped inner wall, within which the liquid medicine resides until droplets appear at the needle tip. The criterion for judging this process is the visible formation of continuous droplets at the needle tip, indicating that the air inside the drug chamber 5 and the needle 6 has been completely expelled, and the entire liquid medicine passage is filled with liquid. The stepper motor 2 then stops and locks.

[0034] Step Two: Precision Injection The control unit applies a driving voltage, starting from 0V and gradually increasing, to the piezoelectric ceramic displacement block 7. Under voltage drive, the piezoelectric ceramic displacement block 7 generates a linear elongation displacement in the micrometer range (1μm~100μm), pushing the conical protrusion end face 41 of the injection rod 4 into the conical space, gradually occupying the internal volume of the conical space, forcibly squeezing the liquid medicine present in the conical space and entering each needle 6 through the needle inlet, and finally injecting it into the skin from the needle tip. When the voltage reaches the preset maximum value, the piezoelectric ceramic displacement block 7 reaches its maximum elongation (preferably 100μm), and a single injection is completed.

[0035] Step 3: Depressurize and reset: The control unit reduces the driving voltage of the piezoelectric ceramic displacement block 7 from its maximum value back to 0V, causing the piezoelectric ceramic to retract and reset. The injection rod 4 is fixedly connected to the piezoelectric ceramic displacement block 7. When the piezoelectric ceramic retracts, it drives the injection rod 4 to retract synchronously, completing the pressure relief. At this time, the residual pressure at the needle tip is eliminated, and the medicine no longer leaks.

[0036] Step 4: Infusion and positioning: If the next injection is required, the control unit controls the stepper motor 2 to drive the injection rod 4 forward again. The control unit converts the preset single injection volume into the number of driving steps of the stepper motor 2, controls the stepper motor 2 to advance the corresponding stroke, so that the injection rod 4 returns to the replenishment position, and then repeats the second and third stages mentioned above.

[0037] Stepper motor 2 propels in one direction throughout the entire process, moving forward only during the coarse pushing and emptying stage and the replenishment and positioning stage, without the need for forward and reverse switching.

[0038] Segmented control of multiple micro-injections: As a preferred embodiment, the piezoelectric ceramic displacement block 7 can adopt a "progressive pulse propulsion" mode during a complete injection process: The control unit divides the total voltage into several equal parts, each corresponding to a tiny displacement increment (e.g., 10 μm each time), and applies them segmentally to the piezoelectric ceramic displacement block 7. There is a short pause between two adjacent voltage increases, so that the drug solution is slowly injected into the skin in the form of multiple micro-pulses. The total displacement of the segmented injection is equal to the target displacement of a single injection (preferably 100 μm).

[0039] Through the above control process, stepper motor 2 stops and locks after completing the coarse pushing and emptying and replenishment positioning, without the need for forward and reverse switching during the entire injection process; piezoelectric ceramic displacement block 7, as the sole injection drive source, completes the micron-level precision injection of the entire set dose of drug solution. The stepper motor 2 and piezoelectric ceramic displacement block 7 have a clear division of labor: stepper motor 2 is responsible for large-stroke mechanical movements, while piezoelectric ceramic displacement block 7 is responsible for high-precision injection, taking into account both the requirements of stroke range and injection accuracy, fundamentally eliminating the cumulative error and drug waste caused by frequent reversals in the traditional "push a few steps and retreat half a step" scheme.

[0040] Example 2: Multi-cavity multi-pump structure The difference between this embodiment and Embodiment 1 lies in the number and arrangement of the drug cavity 5 and the injection rod 4.

[0041] In Example 1, the drug cavity 5 is an integral cavity with a single internal space for storing the drug solution to be injected.

[0042] In this embodiment, as Figure 3 As shown, there is an integral drug chamber 5 shell. The front wall of the shell is a solid structure. Nine needles 6 are directly fixed to the front wall, and the gaps between the nine needles 6 are filled by the solid material of the front wall to ensure the stable installation of each needle 6.

[0043] The interior of the outer shell is divided into nine independent sub-cavities by a partition. Each of the nine sub-cavities corresponds to one of the nine needles 6. The front end of each sub-cavity is directly connected to the internal channel of the corresponding needle 6. That is, the inner wall of the bottom surface of the front end of each sub-cavity is a conical funnel shape with the inner diameter gradually decreasing towards the corresponding needle 6. The inlet of each needle 6 is directly opened at the bottom end of the conical funnel shape of the bottom wall of its corresponding sub-cavity, so that there is no additional flow channel or liquid storage cavity between each sub-cavity and the corresponding needle 6.

[0044] The nine needles are arranged in a ring or matrix.

[0045] Nine injection rods 4 are arranged in each of the sub-cavities. Each injection rod 4 has a tapered boss end face 41 at its front end that matches the tapered inner wall of its corresponding sub-cavity. The rear ends of the nine injection rods 4 are fixedly connected by an integral linkage block 8. All injection rods 4 are axially constrained by the integral linkage block 8, maintaining synchronous movement. A piezoelectric ceramic displacement block 7 is located between the rear end of the integral linkage block 8 and the transmission mechanism 3.

[0046] The control flow in this embodiment is the same as in Embodiment 1, except that: the stepper motor 2 drives the overall linkage block 8 to simultaneously complete the coarse injection and liquid replenishment positioning of the nine injection rods 4, and the piezoelectric ceramic displacement block 7 drives the overall linkage block 8 to simultaneously complete the fine injection of the nine injection rods 4. Since the nine injection rods 4 are fixedly connected by the overall linkage block 8, the single micro-displacement of the piezoelectric ceramic displacement block 7 acts on all injection rods 4 simultaneously, ensuring that the injection dosage of each sub-cavity is completely consistent.

[0047] This design completely eliminates the diversion structure, resulting in a more thorough zero-residue effect. Each sub-cavity is independently connected to its corresponding needle 6, eliminating the problem of residual medication at corners when the medication is diverted from one larger cavity to multiple needles 6. When the injection rod 4 is pushed to the bottom wall, the medication in each cavity is squeezed out more thoroughly, thus achieving zero liquid residue in all nine independent sub-cavities simultaneously.

[0048] Furthermore, each of the nine sub-cavities is equipped with an independent micro-solenoid valve to control the on / off state of each sub-cavity and its corresponding needle 6. The control unit can selectively open the solenoid valves corresponding to some sub-cavities according to a preset zonal drug delivery plan, achieving asymmetric injection. For example, the three middle needles can be opened in the T-zone, and the six peripheral needles can be opened in the cheek zone, with the number of precise injection steps in each zone independently controlled, thereby achieving differentiated drug delivery in a single puncture. The overall linkage block still synchronously pushes the nine injection rods, but through the combination of on / off states of the solenoid valves, differentiated distribution of fluid output from each needle is achieved.

[0049] Each sub-cavity is completely isolated, and the medication does not mix during injection. Each sub-cavity can be independently filled with the same or different formulations of medication, which allows for spatially differentiated distribution of active ingredient dosage within a unit injection volume. In high-end hyaluronic acid treatments, this enables "one injection, multi-point differentiated drug delivery"—for example, zoned treatment plans for T-zone oil control and cheek hydration.

Claims

1. A method for controlling the handle of a water-light injection device, characterized in that, The device includes a handpiece for a mesotherapy injection device. The handpiece comprises a housing, a stepper motor, a transmission mechanism, an injection rod, a drug chamber, a needle, and a control unit. The stepper motor is fixedly installed inside the housing and connected to the injection rod via the transmission mechanism. One end of the drug chamber is an open end for inserting the injection rod, and the other end is a bottom wall. The needle is fixed to the outer surface of the bottom wall, and the needle inlet opens directly onto the inner surface of the bottom wall. The injection rod is slidably disposed within the drug chamber along its axial direction. A piezoelectric ceramic displacement block is provided between the injection rod and the transmission mechanism. The control unit is electrically connected to both the stepper motor and the piezoelectric ceramic displacement block. The control method includes the following steps: Coarse push emptying step: The control unit controls the stepper motor to drive the injection rod forward in one direction, squeezing the liquid medicine in the drug cavity forward until continuous droplets are formed at the tip of the needle, then controls the stepper motor to stop and lock. Precision injection step: The control unit applies an increasing driving voltage to the piezoelectric ceramic displacement block, causing it to produce a micron-level linear elongation displacement, which pushes the injection rod to discharge the drug from the needle tip; Pressure relief and reset steps: The control unit cancels the driving voltage of the piezoelectric ceramic displacement block, causing it to retract and reset, thereby driving the injection rod to retract and release the residual pressure inside the drug cavity; Fluid replenishment positioning step: The control unit converts the preset single injection volume into the number of drive steps of the stepper motor, controls the stepper motor to advance the corresponding stroke, so that the injection rod returns to the fluid replenishment positioning position, and then repeats the above fine injection step and pressure relief reset step.

2. The control method for the handle of a water-light injection device according to claim 1, characterized in that, The control unit applies driving voltage to the piezoelectric ceramic displacement block in segments using a progressive pulse method, with a pause between adjacent voltage applications.

3. The control method for the handle of a water-light injection device according to claim 1, characterized in that, The stepper motor moves forward in one direction throughout the entire injection process without switching between forward and reverse directions.

4. The control method for the handle of a water-light injection device according to claim 1, characterized in that, The linear elongation displacement of the piezoelectric ceramic displacement block is from 1 μm to 100 μm.

5. The control method for the handle of a water-light injection device according to claim 1, characterized in that, The drug chamber is an integral shell, which contains N independent sub-cavities separated by partitions, where N≥2. The front bottom wall of each sub-cavity corresponds to and is directly connected to the internal channel inlet of each needle. Each injection rod is correspondingly installed in each sub-cavity. The rear end of each injection rod is fixedly connected by an integral linkage block. The transmission mechanism is connected to the integral linkage block through the piezoelectric ceramic displacement block. The control unit synchronously drives each injection rod to perform the coarse injection and emptying step, the fine injection step, the pressure relief and reset step, and the fluid replenishment and positioning step through the integral linkage block.

6. The control method for the handle of a water-light injection device according to claim 5, characterized in that, The number N is 9, and the nine needles are arranged in a ring or matrix.

7. The control method for the handle of a water-light injection device according to claim 5, characterized in that, Each sub-cavity is independently filled with the same or different formulations of medicine. When the control unit synchronously drives each injection rod through the overall linkage block, each sub-cavity outputs an equal amount of medicine at the same time.

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