Slit light width adjustment mechanism

Abstract

The present invention provides a slit light width adjustment mechanism, comprising a slit seat, a movable part arranged on the slit seat and a driving assembly, wherein two movable parts are provided, the two movable parts are symmetrically arranged and rotatably connected so that the two movable parts can perform opening and closing movements, and the movable parts are also provided with slit sheets for blocking the light path; a transmission structure arranged between the movable part and the driving assembly converts the driving force of the driving assembly into an opening and closing movement between the two movable parts, thereby changing the light path width between the two slit sheets. Such an adjustment structure has a simple structure, saves the link of force transmission, improves the adjustment accuracy and reliability, and the electric adjustment function facilitates remote control, is beneficial to the judgment of professional doctors, and provides patients with timely and efficient treatment plans.

Description

Technical Field

[0001] The invention relates to the field of slit lamps, and in particular to a slit light width adjustment mechanism. Background Art

[0002] The slit lamp microscope is an important and indispensable pathological diagnostic instrument for ophthalmic medical examination. The slit lamp microscope system used in this profession is usually composed of a slit illumination light generating device and an optical microscope. When the operator operates the slit lamp, one hand is placed on the operating handle of the slit lamp moving platform, and the other hand operates the slit width control knob. When one hand is needed to do other things (such as holding the patient's eyes open with the hand, adjusting the optical body magnification), one hand must leave the above two positions, so that the operation process is interrupted, causing inconvenience. At the same time, the slit width adjustment mechanism in the slit illumination light generating device is composed of a set of stepped transmission mechanical structures, which drives the eccentric cam to rotate through the handwheel rotation mechanism, pushes the long push rod, the long push rod pushes the top block, the top block pushes the short push rod, the short push rod drives the slit cam to move, pushes the slit barrel, and drives the slit block connected to the slit barrel to move to adjust the slit width. There are too many links, the structure is complex, the adjustment accuracy is not high, and the reliability is not good. Summary of the invention

[0003] The main purpose of the present invention is to provide a slit light width adjustment mechanism, aiming to solve the technical problem that the optical path width adjusted manually is not accurate enough.

[0004] The present invention proposes the following technical solutions:

[0005] A slit light width adjustment mechanism comprises a slit seat, a movable part and a driving assembly arranged on the slit seat, and a transmission structure arranged between the movable part and the driving assembly. The movable parts are provided with two, and the two movable parts are rotatably connected so that the two movable parts can perform opening and closing movements. The movable parts are also provided with slit sheets for blocking the light path. The transmission structure converts the driving force of the driving assembly into an opening and closing movement between the two movable parts, thereby changing the light path width between the two slit sheets.

[0006] Furthermore, the transmission structure includes an actuator arranged at the output end of the driving component and a sliding component arranged on the movable component, and a sliding groove adapted to the sliding component is provided on the surface of the actuator opposite to the sliding component; when the driving component drives the actuator to move linearly, as the sliding component slides in the sliding groove, the sliding component drives the two movable components to perform opening and closing movements.

[0007] Furthermore, the slide grooves are two arc-shaped grooves that are symmetrically arranged and in an "eight" shape, and the sliding members on the two movable members are respectively movably engaged in the two arc-shaped grooves.

[0008] Furthermore, when the sliding member slides to the highest point of the arc-shaped groove, the optical path width between the two slit pieces is a minimum value; when the sliding member slides to the lowest point of the arc-shaped groove, the optical path width between the two slit pieces is a maximum value.

[0009] Furthermore, when the sliding member slides toward the highest point of the arc groove, the outer peripheral surface of the bearing abuts against the upper side surface of the arc groove; when the sliding member slides toward the lowest point of the arc groove, the outer peripheral surface of the bearing abuts against the lower side surface of the arc groove.

[0010] Furthermore, the sliding member is a slider disposed on the outer side surface of the movable member, the outer peripheral surface of the slider abuts against two opposite side surfaces in the arc-shaped groove, and the slider slides in the slide groove in a sliding manner.

[0011] Furthermore, the movable part is a semi-barrel structure, having a semi-annular bottom surface and a side surface extending upward around the outer arc of the bottom surface, a semi-annular clamp is formed on the top of the side edge of the side surface, a fixed shaft is clamped between two of the clamps, and a ring is sleeved on the outer circumference of the two clamps, and the two clamps can rotate in the gap between the fixed shaft and the ring.

[0012] Furthermore, the slit pieces are arranged on the outer bottom surface of the movable part, and the opposite sides of the two slit pieces form an inclined surface.

[0013] Furthermore, a U-shaped spring is provided between the two movable parts, one end of the spring is fixed on the inner wall surface of one of the movable parts, and the other end is fixed on the inner wall surface of the other movable part. The restoring force of the spring and the driving force of the driving assembly cooperate to keep the opening and closing movement between the two movable parts stable.

[0014] Furthermore, the driving assembly includes a limit shaft arranged on the motor seat, a driving motor arranged on the motor seat, a screw rod arranged at the output end of the driving motor, and a nut seat arranged on the screw rod, the nut seat is fixedly connected to the actuator, and the limit shaft is passed through the actuator.

[0015] The present invention provides a slit light width adjustment mechanism, comprising a slit seat, a movable part arranged on the slit seat and a driving assembly, wherein two movable parts are provided, the two movable parts are symmetrically arranged and rotatably connected so that the two movable parts can perform opening and closing movements, and the movable parts are also provided with slit sheets for blocking the light path; a transmission structure arranged between the movable part and the driving assembly converts the driving force of the driving assembly into an opening and closing movement between the two movable parts, thereby changing the light path width between the two slit sheets. Such an adjustment structure has a simple structure, saves the force transmission link, and improves the adjustment accuracy and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the adjustment mechanism of the slit light width of the present invention;

[0017] Figure 2 An exploded view of the adjustment mechanism for the slit light width of the present invention;

[0018] Figure 3 This is a schematic diagram of the structure of the drive assembly of the present invention;

[0019] Figure 4 It is a schematic diagram of the connection structure between the driving assembly and the movable part of the present invention;

[0020] Figure 5 It is a structural schematic diagram of the movable part of the present invention;

[0021] Figure 6 A structural schematic diagram of the movable part of the present invention from another angle

[0022] Figure 7 It is a schematic diagram of the structure of the actuator.

[0023] The names of the components marked in the figure are as follows: 2. Slit seat; 3. Actuator; 31. Arc groove; 32. Longitudinal portion; 33. Transverse portion; 331. Round hole; 332. Limit hole; 4. Slit plate; 5. Movable part; 51. Fixed shaft; 52. Ring; 53. Spring; 54. Clamp; 55. Sliding part; 6. Spotlight assembly; 7. Lighting assembly; 11. Driving motor; 12. Screw; 13. Motor seat; 14. Limit shaft; 15. Nut seat.

[0024] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0025] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0026] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0029] Reference Figures 1 to 7, a slit light width adjustment mechanism, comprising a slit seat 2, a movable part 5 and a driving assembly arranged on the slit seat 2, and a transmission structure arranged between the movable part 5 and the driving assembly, wherein two movable parts 5 are provided, and the two movable parts 5 are rotatably connected so that the two movable parts 5 can perform opening and closing movements, and the movable parts 5 are also provided with a slit sheet 4 for blocking the light path; the transmission structure converts the driving force of the driving assembly into an opening and closing movement between the two movable parts 5, thereby changing the light path width between the two slit sheets 4. In this embodiment, a lighting lamp assembly 7 and a spotlight assembly 6 are arranged above the slit seat 2, and the lighting lamp assembly 7 is located above the spotlight assembly 6. During operation, the uppermost lighting lamp assembly 7 emits slit light, which is first adjusted by the spotlight assembly 6 for focusing, and finally the light path width is adjusted by the slit light width adjustment mechanism. The slit light passes through the gap between the two slit pieces 4, and the driving component is used to adjust the width of the gap between the two slit pieces 4 by cooperating with the transmission mechanism; that is, the width of the gap between the two slit pieces 4 is the width of the slit light, so the width of the slit light can be controlled by controlling the distance between the two slit pieces 4.

[0030] Specifically, the transmission structure includes an actuator 3 disposed at the output end of the driving component and a sliding member 55 disposed on the movable member 5. A sliding groove adapted to the sliding member 55 is provided on the surface of the actuator 3 opposite to the sliding member 55. When the driving component drives the actuator 3 to move linearly, as the sliding member 55 slides in the sliding groove, the sliding member 55 drives the two movable members 5 to open and close. In a feasible embodiment, the sliding groove is two arc grooves 31 symmetrically arranged in an "eight" shape, and the sliding members 55 on the two movable members 5 are respectively movably engaged in the two arc grooves 31. Figure 3 As shown, the opening of the arc groove 31 of the "eight"-shaped structure in this embodiment is downward, so the distance between the top ends of the two arc grooves 31 is the shortest, and correspondingly, the distance between the bottom ends of the two arc grooves 31 is the farthest. Therefore, when the sliding member 55 slides to the highest point of the arc groove 31, the optical path width between the two slit pieces 4 is the minimum value; when the sliding member 55 slides to the lowest point of the arc groove 31, the optical path width between the two slit pieces 4 is the maximum value.

[0031] In another feasible embodiment (not shown in the drawings), the opening of the arc groove 31 of the "eight"-shaped structure is upward, that is, the "eight"-shaped structure in this embodiment is inverted. Therefore, this embodiment is different from the embodiment of the "eight"-shaped structure in the forward direction. Specifically, the distance between the top ends of two arc grooves 31 is the farthest, and correspondingly, the distance between the ends of two arc grooves 31 is the shortest. Therefore, when the sliding member 55 slides to the highest point of the arc groove 31, the optical path width between the two slit pieces 4 is the maximum value; when the sliding member 55 slides to the lowest point of the arc groove 31, the optical path width between the two slit pieces 4 is the minimum value.

[0032] Specifically, Figure 3 As shown, in a feasible embodiment, the sliding member 55 is a bearing disposed on the outer side of the movable member 5. When the sliding member 55 slides toward the highest point of the arc groove 31, the outer peripheral surface of the bearing abuts against the upper side of the arc groove 31; when the sliding member 55 slides toward the lowest point of the arc groove 31, the outer peripheral surface of the bearing abuts against the lower side of the arc groove 31. In this embodiment, the cooperation between the bearing and the arc groove 31 supports and drives the two movable members 5 to open and close. If the sliding member 55 (such as a shaft) is directly matched with the arc groove 31, firstly, the transmission resistance is large, and it is difficult to ensure the accuracy of the width between the two slit pieces 4; secondly, the wear is large, and the sliding member 55 is not easy to replace, which shortens the service life of the equipment. The bearing contacts the arc groove 31 by rolling between elements. Therefore, using the bearing as the sliding member 55 during the transmission process has the advantages of small sliding resistance, low power consumption, and easy starting. In addition, the sliding member reduces the friction coefficient during the movement process when sliding in the arc groove 31, reduces the transmission resistance, and ensures the accuracy of the width between the two slit pieces 4.

[0033] As an alternative, in another feasible embodiment, the sliding member 55 is a slider (not shown in the drawings) provided on the outer side of the movable member 5, the outer peripheral surface of the slider abuts against two opposite side surfaces in the arc groove 31, and the slider slides in the slide groove in a sliding manner. The material of the slider in this embodiment is a wear-resistant material with a hardness less than that of the arc groove 31. The arc groove 31 with this structure supports the slider, which improves the stability of the slider sliding in the arc groove 31; in addition, since the hardness of the slider is less than the hardness of the arc groove 31, it can ensure that the wear on the arc groove 31 is reduced, and when parts need to be replaced, only the slider needs to be replaced. At the same time, the material of the slider is a self-lubricating material to improve the wear resistance between the slider and the arc groove 31.

[0034] In a feasible embodiment, the movable part 5 is a semi-barrel structure, having a semi-annular bottom surface and a side surface extending upward around the outer arc of the bottom surface. Since the light emitted by the lighting lamp assembly 7 is concentrated by the spotlight assembly 6, the light path formed is cylindrical. When the two opposite sides of the slit pieces 4 are fitted, a circular through hole is formed in the center of the two semi-annular bottom surfaces for the light path to pass through, so that the light can be irradiated on the slit pieces 4, and the width of the light is controlled by the opening and closing distance between the slit pieces 4. In addition, a semi-annular clamp 54 is formed on the top of the side edge of the side, and a fixed shaft 51 is clamped between the two clamps 54. The outer peripheral surfaces of the two clamps 54 are sleeved with a ferrule 52, and the two clamps 54 are rotated in the gap between the fixed shaft 51 and the ferrule 52. Among them, the fixed shaft 51 is fixed to the inner side wall of the slit seat 2. The design of the above-mentioned rotating structure is simple, which can ensure that the two movable parts 5 are opened and closed synchronously, thereby achieving the purpose of accurately controlling the width between the two slit pieces 4.

[0035] Furthermore, the slit pieces 4 are arranged on the outer bottom surface of the movable part, and the opposite sides of the two slit pieces 4 form an inclined surface. When the slit lamp microscope is used to examine the eyeball, the light path used not only has requirements on the width, but also has very high requirements on the flatness of the edge of the light path. The width of the light path is determined by the distance between the opposite sides of the two slit pieces 4. When the light passes through the opposite side of the slit pieces 4, the longer the path the light passes, the more the flatness of the edge of the light path is affected. Therefore, when the opposite side of the two slit pieces 4 forms an inclined surface, the opposite side is the thinner side, the shorter the path the light passes, and the less the flatness is affected. Moreover, it is more convenient to perform fine processing on the inclined surface on the slit piece 4, saving the cost required for fine processing.

[0036] As an alternative, in another embodiment, the movable member 5 is a semi-cube structure, having a rectangular bottom surface and a side surface extending upward around the bottom surface, a semi-circular clamp 54 is formed on the top of the side edge of the side surface, a fixed shaft 51 is clamped between the two clamps 54, and a ferrule 52 is sleeved on the outer peripheral surface of the two clamps 54, and the two clamps 54 are rotated in the gap between the fixed shaft 51 and the ferrule 52. Among them, the fixed shaft 51 is fixed on the inner side wall of the slit seat 2. Based on the above embodiment, another feasible technical solution of the transmission structure can be derived. The transmission structure includes an actuator 3 arranged at the output end of the drive assembly, a sliding member 55 arranged on the actuator 3, and a slide groove opened on the side surface to match the sliding member 55. Since the design of the slide groove needs to be carried out on a plane, when the movable member 5 is a cube, its side surface is a plane, which can realize the setting of the arc groove 31. Similarly, when the driving assembly drives the actuator 3 to move up and down, as the sliding member 55 slides in the slide groove, the sliding member 55 drives the two movable members 5 to perform opening and closing movements. Since the position of the sliding member 55 in this embodiment has changed, the sliding member is at different positions in the arc groove 31, and the opening and closing states between the two movable members 5 are also different. Specifically, the "eight"-shaped opening of the arc groove 31 provided on the movable member 5 is downward. At this time, the two arc grooves 31 are respectively located on the two movable members 5, and the distance between the top ends of the two arc grooves 31 is the shortest. Correspondingly, the distance between the end ends of the two arc grooves 31 is the farthest. Therefore, when the sliding member 55 slides to the highest point of the arc groove 31, the optical path width between the two slit pieces 4 is the minimum value; when the sliding member 55 slides to the lowest point of the arc groove 31, the optical path width between the two slit pieces 4 is the maximum value. The "eight"-shaped opening of the arc groove 31 provided on the movable member 5 is facing upward, that is, the "eight"-shaped structure is inverted. At this time, the two arc grooves 31 are respectively located on the two movable members 5, and the distance between the top ends of the two arc grooves 31 is the farthest, and correspondingly, the distance between the bottom ends of the two arc grooves 31 is the shortest. Therefore, when the sliding member 55 slides to the highest point of the arc groove 31, the optical path width between the two slit pieces 4 is the maximum value; when the sliding member 55 slides to the lowest point of the arc groove 31, the optical path width between the two slit pieces 4 is the minimum value.

[0037] Whether the two movable parts 5 are in the process of opening and closing movement or in a fixed position during inspection, they cannot keep the distance between the two slit pieces 4 in a stable state, which will cause the optical path width to change during the inspection process, affecting the final inspection result. Therefore, in a feasible embodiment, a U-shaped spring 53 is arranged between the two movable parts 5, one end of the spring 53 is fixed on the inner wall surface of one of the movable parts 5, and the other end is fixed on the inner wall surface of the other movable part 5. The restoring force of the spring 53 and the driving force of the driving component cooperate to keep the opening and closing movement between the two movable parts 5 stable. In addition, when performing an inspection, the restoring force of the spring 53 and the driving force of the driving component cooperate to keep the distance between the two slit pieces 4 in a stable state. The U-shaped spring 53 can be arranged in a variety of ways. For example, a horizontally placed U-shaped spring 53. Or as Figure 4 As shown, the free end of the U-shaped spring 53 is bent at 90 degrees so that it is connected to the two movable parts 5 in the horizontal direction, and the other part is located in the vertical direction. This arrangement can prevent the spring 53 from affecting the optical path of the slit light.

[0038] There are many specific structures of the drive assembly. For example, a linear module, a gear and rack meshing transmission method, and a cylinder as a power source. Any mechanical structure that can achieve linear motion can be applied to this solution. In a more preferred embodiment, the drive assembly includes a limit shaft 14 arranged on a motor seat 13, a drive motor 11 arranged on the motor seat 13, a screw rod 12 arranged at the output end of the drive motor 11, and a nut seat 15 arranged on the screw rod 12, the nut seat 15 is fixedly connected to the actuator 3, and the limit shaft 14 is inserted into the actuator 3. When the drive motor 11 starts to work, the screw rod 12 rotates under the drive of the drive motor 11, and the nut seat 15 tends to rotate under the action of the screw rod 12, but because the limit shaft 14 is fixed on the motor seat 13 and inserted on the actuator 3, and the actuator 3 is fixedly connected to the nut seat 15, the actuator 3 moves up and down under the joint action of the nut seat 15 and the limit shaft 14. The actuator 3 changes the opening and closing size of the movable member 5 during the displacement process. The electric adjustment function provides convenience for remote control, facilitates the judgment of professional doctors, and provides patients with timely and efficient treatment plans. Figure 6 As shown, the actuator 3 is a T-shaped structure, including a longitudinal portion 32 with a slide groove and a transverse portion 33 perpendicular to the longitudinal portion 32. The end of the transverse portion 33 forms a circular hole 331 for the screw rod 12 to pass through. The transverse portion 33 also has a limiting hole 332 that cooperates with the limiting shaft 14, and the limiting hole 332 is located between the circular hole 331 and the longitudinal portion 32. Such a structural design is simple and reduces the space occupied by each component.

[0039] The adjustment mechanism of the slit light width in this embodiment is controlled by a control panel, and the driving component, the lighting component and the spotlight component are respectively connected to the control panel and driven by the control panel. A control panel is set up, and when it is necessary to adjust the parameters of the slit light, it is only necessary to send a control instruction to the control panel, and the control panel controls the corresponding components to make corresponding operations, thereby realizing the control of each component. However, this embodiment is not limited to the method of sending control instructions to the control panel. Specifically, button control, remote control, intelligent control or remote control in the prior art can be used. When applying, those skilled in the art can apply the existing control method to this embodiment in combination with actual needs, and no cumbersome description is made here.

[0040] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A slit light width adjustment mechanism, characterized in that: It comprises a slit seat, a movable part and a driving assembly arranged on the slit seat, and a transmission structure arranged between the movable part and the driving assembly, wherein two movable parts are provided, and the two movable parts are rotatably connected so that the two movable parts can perform opening and closing movements, and the movable parts are also provided with a slit sheet for shielding the light path; the transmission structure converts the driving force of the driving assembly into an opening and closing movement between the two movable parts, thereby changing the light path width between the two slit sheets; The movable part is a semi-cube structure, having a rectangular bottom surface and a side surface extending upward around the bottom surface, a semi-annular clamp is formed on the top of the side edge of the side surface, a fixed shaft is clamped between the two clamps, and a ferrule is sleeved on the outer circumference of the two clamps, and the two clamps rotate in the gap between the fixed shaft and the ferrule; the transmission structure includes an actuating member arranged at the output end of the driving component, a sliding member arranged on the actuating member, and a sliding groove adapted to the sliding member opened on the side surface, and the driving component drives the actuating member to move. When the movable member moves linearly, as the sliding member slides in the sliding groove, the sliding member drives the two movable members to perform opening and closing movements; the sliding groove is two arc-shaped grooves symmetrically arranged and opening upward, and the sliding members on the two movable members are respectively engaged in the two arc-shaped grooves in a movable manner; when the sliding member slides to the highest point of the arc-shaped groove, the optical path width between the two slit pieces is the maximum value; when the sliding member slides to the lowest point of the arc-shaped groove, the optical path width between the two slit pieces is the minimum value; The driving assembly includes a limiting shaft arranged on a motor seat, a driving motor arranged on the motor seat, a lead screw arranged at an output end of the driving motor, and a nut seat arranged on the lead screw, the nut seat is fixedly connected to the actuator, the limiting shaft is passed through the actuator, wherein the actuator moves up and down under the joint action of the nut seat and the limiting shaft, the actuator is a T-shaped structure, including a longitudinal portion with the slide groove and a transverse portion perpendicular to the longitudinal portion, a circular hole is formed at the end of the transverse portion for the lead screw to pass through, the transverse portion is also provided with a limiting hole that cooperates with the limiting shaft, and the limiting hole is located between the circular hole and the longitudinal portion.

2. The slit light width adjustment mechanism according to claim 1, characterized in that: The sliding member is a bearing arranged on the outer side surface of the movable member. When the sliding member slides toward the highest point of the arc groove, the outer peripheral surface of the bearing abuts against the upper side surface of the arc groove; when the sliding member slides toward the lowest point of the arc groove, the outer peripheral surface of the bearing abuts against the lower side surface of the arc groove.

3. The slit light width adjustment mechanism according to claim 1, characterized in that: The sliding member is a slider disposed on the outer side surface of the movable member, the outer peripheral surface of the slider abuts against two opposite side surfaces in the arc-shaped groove, and the slider slides in the slide groove in a sliding manner.

4. The slit light width adjustment mechanism according to claim 1, characterized in that: The slit pieces are arranged on the outer bottom surface of the movable part, and the opposite sides of the two slit pieces form an inclined surface.

5. The slit light width adjustment mechanism according to claim 1, characterized in that: A spring with a U-shaped structure is arranged between the two movable parts, one end of the spring is fixed on the inner wall surface of one of the movable parts, and the other end of the spring is fixed on the inner wall surface of the other movable part.

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