Pseudo-ejector-pin contact-type terminal equipment disassembling and counting device

Abstract

The invention relates to a false ejector pin contact type terminal equipment disassembling and counting device which comprises a shell, a pushing and pressing mechanism, a chassis and a signal conversion PCB, the pushing and pressing mechanism is arranged at the top of the shell in a penetrating mode and can reciprocate in the vertical direction, the signal conversion PCB is fixed to the bottom of the shell, and the chassis is arranged at the top of the signal conversion PCB and connected to the pushing and pressing mechanism; the pushing and pressing mechanism can drive the base plate to rotate around the center of the base plate in a stepping mode every time the pushing and pressing mechanism reciprocates, a metal conducting strip is arranged on the bottom face of the base plate, an OUT contact and a plurality of output contacts are arranged on the top face of the signal conversion PCB, and the metal conducting strip rotates along with the base plate in a stepping mode to sequentially communicate the OUT contact with the output contacts. The beneficial effects of the invention are that disassembly counting in an off-electricity state can be realized without power supply, terminal safety is guaranteed, digital / analog output is supported, adaptability is high, the structure is compact, cost is low, and mass production is easy.

Description

Technical Field

[0001] This invention relates to the field of terminal security technology, specifically to a device for counting the number of times a pseudo-pin contact type terminal device can be disassembled. Background Technology

[0002] Modern smartphones and other terminal devices have a certain degree of water and dust resistance. The fit of components such as the battery cover and screen has a significant impact on this capability. Unauthorized disassembly of these devices by non-professionals may pose safety hazards, compromising the device's security. Furthermore, the lack of testing on the number of disassemblies during disassembly makes it impossible to verify whether the device is a resealed device. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a pseudo-pin contact type terminal device for disassembly counting. Through mechanical structure combined with conversion circuit and simple software algorithm, it can realize the function of disassembly counting of terminal devices. The device is small in size, simple in structure, easy to manufacture and low in cost.

[0004] The objective of this invention is achieved through the following technical solution: A device for disassembling and counting pseudo-pin contact terminal equipment includes a housing, a pushing mechanism, a chassis, and a signal conversion PCB. The pushing mechanism is installed on the top of the housing and can reciprocate vertically. The signal conversion PCB is fixed to the bottom of the housing. The chassis is located on top of the signal conversion PCB and connected to the pushing mechanism. Each reciprocating movement of the pushing mechanism can drive the chassis to rotate once around the center of the chassis. A metal conductive sheet is provided on the bottom surface of the chassis. An OUT contact and multiple output contacts are provided on the top surface of the signal conversion PCB. The metal conductive sheet connects the OUT contact and the multiple output contacts sequentially as the chassis rotates. Furthermore, the pushing mechanism includes a push rod, a middle rod, and a spring. A cylindrical through hole is provided in the middle of the housing along the vertical direction. The bottom of the push rod passes through the top of the through hole and can move vertically. The middle rod and the spring are arranged in the through hole from top to bottom. The bottom of the push rod is open and the top of the middle rod rotates through the bottom of the push rod. The two ends of the spring are fixed to the middle rod and the base respectively. Multiple guide slopes are evenly arranged around the center line of the through hole on the inner wall of the housing. The multiple guide slopes are connected end to end. The bottom of the push rod is provided with a ratchet in the shape of a sawtooth. The bottom of the outer wall of the middle rod is provided with a sloping wall protrusion. When the push rod moves vertically downward, the ratchet pushes the sloping wall protrusion to move vertically downward along the guide slope. When the push rod moves vertically upward, the spring pushes the sloping wall protrusion to rotate spirally upward along the guide slope.

[0005] Furthermore, the inner wall of the outer casing is uniformly provided with multiple vertical linear guide grooves around the center line of the through hole, and the outer wall of the push rod is provided with guide protrusions that are slidably connected to the linear guide grooves one by one.

[0006] Furthermore, the ratchet includes a first tooth inclined surface and a second tooth inclined surface that are spaced apart. When the push rod moves back and forth, the top of the inclined wall protrusion slides along the first tooth inclined surface and the second tooth inclined surface in sequence.

[0007] Furthermore, a limiting protrusion is provided on the inner wall of the bottom of the housing, and a limiting groove is provided on the outer edge of the signal conversion PCB to engage with the limiting protrusion.

[0008] Furthermore, the signal conversion PCB is an analog signal conversion PCB, with multiple output contacts distributed in a circular array centered on the OUT contact.

[0009] Furthermore, the signal conversion PCB is a Gray code digital encoder conversion PCB, with multiple output contacts distributed in concentric circles from the inside out, centered on the OUT contact.

[0010] Furthermore, the inner wall of the outer casing is provided with a limiting stop bar, and the outer edge of the chassis is provided with a limiting block that can abut against the limiting stop bar.

[0011] Furthermore, the bottom surface of the central rod is provided with a base groove, the bottom of the base groove is provided with a first spring groove, the top surface of the chassis is provided with a second spring groove, and the two ends of the spring are respectively fixed in the first spring groove and the second spring groove.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The pseudo-pin contact type terminal device disassembly counting device of the present invention can be installed inside the terminal device. When disassembling and assembling the terminal device, the arrangement of the shell, the pushing mechanism, the chassis and the signal conversion PCB allows the pushing mechanism to drive the chassis to rotate once around the center of the chassis with each reciprocating movement in the vertical direction. This allows the metal conductive sheet on the chassis to connect the OUT contact on the signal conversion PCB with multiple output contacts in sequence as the chassis rotates. The number of disassemblies can then be obtained based on the voltage signal output by the sequential connection of the OUT contact with multiple output contacts, thus realizing the disassembly counting detection of the terminal device.

[0013] 2. This invention uses a mechanical structure combined with a conversion circuit and a simple software algorithm to achieve disassembly counting in the off-power state, so as to ensure terminal safety. The overall structure is compact, low in cost, and easy to mass-produce. Attached Figure Description

[0014] Figure 1 This is a schematic cross-sectional view of the overall structure of the present invention; Figure 2 This is an exploded view of the overall structure of the present invention; Figure 3 This is a perspective structural diagram of the outer shell in this invention; Figure 4 This is a perspective structural diagram of the push rod in this invention; Figure 5 This is a perspective structural diagram of the central rod in this invention; Figure 6 This is a perspective structural diagram of the chassis in this invention; Figure 7 This is a perspective view of the analog signal conversion PCB in this invention; Figure 8 This is a schematic diagram of the limiting post in this invention; Figure 9 This is a perspective view of the PCB structure of the Gray code digital encoder in this invention. Figure 10 A schematic diagram of the movement of the disassembly counting device in the terminal equipment's back cover closing process for a pseudo-pin contact terminal device. Figure 11 A schematic diagram of the movement of the disassembly counting device of a pseudo-pin contact terminal device during the opening of the back cover of the terminal device. Figure 12 This is a schematic diagram of the analog signal output circuit in this invention; Figure 13 This is a schematic diagram of the digital signal output circuit in this invention; Figure 14 This is a table showing the number of times Gray code inverse code is activated and its binary correspondence in this invention.

[0015] In the diagram: 1. Outer shell; 101. Guide slope; 102. Straight guide groove; 103. Inner wall of outer shell; 104. Limiting protrusion; 2. Push rod; 201. Circular top; 202. Inner wall of push rod; 203. Outer wall of push rod; 204. Guide protrusion; 205. First tooth slope; 206. Second tooth slope; 3. Middle rod; 301. Sloping wall protrusion; 302. Outer wall of middle rod; 303. First spring groove; 304. Base groove; 4. Spring; 5. Chassis; 501. Second spring groove; 502. Outer wall of chassis; 503. Metal conductive sheet; 6. Conversion PCB; 601. OUT contact; 602. Output contact. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0017] Example 1 like Figure 1 , Figure 2As shown, a device for disassembling and counting pseudo-pin OUT contact terminal equipment includes a housing 1, a pushing mechanism, a chassis 5, and a signal conversion PCB 6. The pushing mechanism is installed on the top of the housing 1 and can reciprocate vertically. The signal conversion PCB 6 is fixed to the bottom of the housing 1. The chassis 5 is located on the top of the signal conversion PCB 6 and connected to the pushing mechanism. Each reciprocating movement of the pushing mechanism can drive the chassis 5 to rotate once around the center of the chassis 5. A metal conductive sheet 503 is provided on the bottom surface of the chassis 5. An OUT contact 601 and multiple output contacts 602 are provided on the top surface of the signal conversion PCB 6. The metal conductive sheet 503 connects the OUT contact 601 and the multiple output contacts 602 sequentially as the chassis 5 rotates. In this embodiment, the signal conversion PCB6 is an analog signal conversion PCB, and multiple output contacts 602 are arranged in a circular array with the OUT contact 601 as the center. A pseudo-pin OUT contact type terminal device disassembly counting device is installed inside the terminal device. During the assembly and disassembly process, the outer shell 1 and the conversion PCB6 remain fixed. The pushing mechanism reciprocates vertically and drives the chassis 5 to rotate stepwise. The angle of the chassis 5's stepwise rotation is the same as the array angle between two adjacent output contacts 602, allowing the metal conductive sheet 503 to sequentially connect the OUT contact 601 to the multiple output contacts 602 as the chassis 5 rotates. The output voltage is different when the OUT contact 601 is connected to different output contacts 602. Different output voltages correspond to different chassis 5 rotation angles, thus achieving analog signal output. By comparing the real-time rotation angle of the chassis 5 obtained during terminal device disassembly with the initial angle, the corresponding disassembly count can be obtained, thereby realizing the disassembly counting detection of the terminal device.

[0018] like Figure 1 As shown, the pushing mechanism includes a push rod 2, a middle rod 3, and a spring 4. A cylindrical through hole is provided in the middle of the outer shell 1 along the vertical direction. The bottom of the push rod 2 passes through the top of the through hole and can move along the vertical direction. The middle rod 3 and the spring 4 are arranged in the through hole from top to bottom. The bottom of the push rod 2 is open and the top of the middle rod 3 rotates through the bottom of the push rod 2. The two ends of the spring 4 are fixed to the middle rod 3 and the base plate 5, respectively.

[0019] like Figure 3 , Figure 4 , Figure 7As shown, the outer casing 1 includes an inner wall 103 (i.e., the through-hole sidewall), and the inner wall 103 is uniformly provided with multiple vertical linear guide grooves 102 around the center line of the through-hole; the push rod 2 includes a push rod inner wall 202, a push rod outer wall 203, and a circular top 201. The circular top 201 is used to achieve stable triggering at different angles. Multiple guide protrusions 204 are fixed on the push rod outer wall 203, and the guide protrusions 204 are integrally formed with the push rod 2; the multiple guide protrusions 204 are slidably connected to the multiple linear guide grooves 102 in a one-to-one correspondence, so that the push rod 2 can only move in the vertical direction. The bottom inner wall of the outer casing 1 is provided with a limiting protrusion 104, and the limiting protrusion 104 is integrally formed with the outer casing 1. The outer edge of the signal conversion PCB 6 is provided with a limiting groove that can engage with the limiting protrusion 104. The signal conversion PCB 6 is fixed to the bottom of the outer casing 1 by the engaging cooperation between the limiting protrusion 104 and the limiting groove.

[0020] like Figure 3 , Figure 4 As shown, the inner wall 103 of the outer shell is uniformly provided with multiple guide slopes 101 around the center line of the through hole. The multiple guide slopes 101 are connected end to end. The guide slopes 101 are inverted V-shaped, and one end of the guide slopes 101 is vertical and the other end is inclined. The bottom of the push rod 2 is provided with a ratchet in the shape of a sawtooth. The ratchet includes a first tooth slope 205 and a second tooth slope 206 distributed at intervals. The bottom of the outer wall of the middle rod 3 is provided with a sloped wall protrusion 301. The sloped wall protrusion 301 is integrally formed with the middle rod 3. The ratchet abuts against the sloped wall protrusion 301.

[0021] Before assembly, the inclined wall protrusion 301 is located in the middle of the guide slope 101. During assembly, the terminal device's housing presses the push rod 2, causing it to move vertically downwards. The ratchet pushes the inclined wall protrusion 301 along the vertical end of the guide slope 101, thereby causing the inclined wall protrusion 301 and the middle rod 3 to move vertically downwards synchronously. During the downward movement, the spring 4 is compressed. When the inclined wall protrusion 301 disengages from the vertical end of the previous guide slope 101, as the ratchet continues to push the inclined wall protrusion 301, it slides relative to the ratchet along the first toothed slope 205, causing the inclined wall protrusion 301 and the middle rod 3 to rotate synchronously until the inclined wall protrusion 301 moves to the inclined end of the next guide slope 101. At this point, the terminal device is installed, and the metal conductive sheet 503 connects the OUT contact 601 with an output contact 602. When disassembling the terminal device, the terminal device's housing releases the push rod 2. Under the restoring force of spring 4, the spring 4 pushes the middle rod 3 upward, causing the inclined wall protrusion 301 to move along the inclined end of the guide slope 101. This causes the inclined wall protrusion 301 and the middle rod 3 to rotate spirally upward along the guide slope 101. When the push rod 2 rotates, it drives the chassis 5 to rotate synchronously through spring 4. During the rotation, the inclined wall protrusion 301 moves relative to the ratchet along the second tooth slope 206, causing the inclined wall protrusion 301 to push the push rod 2 upward until the disassembly is completed. At this point, the guide protrusion 204 moves to the upper end of the linear guide groove 102, the push rod 2 stops moving, and the metal conductive sheet 503 rotates with the chassis 5 and connects the OUT contact 601 to the next output contact 602. In this way, when disassembling the terminal equipment, the real-time rotation angle of the chassis 5 can be obtained based on the output voltage at the time of disassembly completion. By comparing the real-time rotation angle of the chassis 5 with the initial angle, the number of times the terminal equipment has been disassembled can be obtained.

[0022] like Figure 5 , Figure 6 As shown, the middle rod 3 includes a middle rod outer wall 302, and a base groove 304 is provided on the bottom surface of the middle rod 3. A first spring groove 303 is provided at the bottom of the base groove 304. The chassis 5 includes a chassis outer wall 502, and a second spring groove 501 is provided on the top surface of the chassis 5. The two ends of the spring 4 are respectively fixed in the first spring groove 303 and the second spring groove 501. The base groove 304 can improve the utilization rate of the internal space, so that the middle rod 3 has a greater stroke when it moves downward.

[0023] Taking the first disassembly and assembly of the back cover of the terminal device as an example, there are 8 output contacts 602, the array angle between two adjacent output contacts 602 is 45°, and the stepping rotation angle of the chassis 5 is 45°. The above-mentioned pseudo-pin OUT contact type terminal device disassembly counting device is applied to the terminal device assembly process as follows: The movement trajectory of the disassembly and counting device during the assembly of the back cover is as follows: Figure 10As shown, before assembly, push rod 2 and middle rod 3 are in their initial positions, and spring 4 naturally extends. When assembling the back cover, push rod 2 moves downward along the straight guide groove 102 under the push force of the back cover. The ratchet pushes the inclined wall protrusion 301 downward along the vertical end of the guide inclined surface 101, thereby driving the middle rod 3 downward. When the inclined wall protrusion 301 moves to the connection point of two adjacent guide inclined surfaces 101, push rod 2 continues to push the inclined wall protrusion 301, so that the inclined wall protrusion 301 slides relative to the inclined tooth along the first tooth inclined surface 205, thereby causing the inclined wall protrusion 301 and the middle rod 3 to rotate synchronously. At the same time, the middle rod 3 drives the chassis 5 to rotate through spring 4. When the back cover is completely closed, the inclined wall protrusion 301 moves to the inclined end of the next guide inclined surface 101, spring 4 is in a compressed state, and metal conductive sheet 503 connects OUT contact 601 with the first output contact 602 to obtain the initial output voltage. The entire device is in a closed state.

[0024] The movement trajectory of the disassembly and disassembly of the counting device during the removal of the back cover is as follows: Figure 11 As shown, when the back cover is removed, the push rod 2 is no longer restricted by the back cover. The spring 4 extends and pushes the middle rod 3 and the push rod 2 upwards simultaneously, causing the inclined wall protrusion 301 to move along the inclined end of the guide inclined surface 101 and the inclined wall protrusion 301 to slide relative to the ratchet along the second tooth inclined surface 206. This causes the inclined wall protrusion 301 and the middle rod 3 to rotate upwards in a spiral motion. At the same time, the middle rod 3 drives the chassis 5 to rotate through the spring 4. When the back cover is completely removed, the guide protrusion 204 on the push rod 2 moves to the upper end of the linear guide groove 102. The push rod 2, the middle rod 3, the spring 4 and the chassis 5 stop moving. At this time, the disassembly counting device is in the triggered state. The chassis 5 rotates step by step at an angle. The metal conductive sheet 503 connects the OUT contact 601 with the second output contact 602 and obtains the real-time output voltage after the first removal of the back cover.

[0025] like Figure 12 As shown, the eight output contacts 602 are arranged in the order of 1-8. Assuming the initial position of the chassis 5 before the back cover is removed is -10°, the metal conductive sheet 503 connects output contact 602 (1) with the OUT contact 601. According to Ohm's law, the corresponding output voltage is 3.25V. When the disassembly counting device moves from the closed state to the triggered state, output contact 602 (1) disconnects from the OUT contact 601, and the metal conductive sheet 503 connects output contact 602 (2) with the OUT contact 601. Assuming the output voltage is 2.8V, the chassis 5 rotates to -55°, meaning the chassis 5 rotates 45°, thus recording one disassembly of the back cover. This process can be repeated to achieve the disassembly counting detection of the terminal device.

[0026] When repeating the above process of disassembling and assembling the back cover, the rotation angle of the chassis 5 can be obtained from the real-time output voltage obtained when the back cover is finally removed, that is, the output analog signal. By comparing it with the initial angle, the number of steps of the chassis 5 can be obtained. The number of steps of rotation is the number of times the back cover is disassembled, thereby realizing the disassembly counting detection.

[0027] Implementation of Column 2 like Figure 8 As shown, based on the structure of the disassembly counting device for the pseudo-pin OUT contact terminal device in Embodiment 1, this embodiment adds a limiting stop bar integrally formed with the outer shell 1 to the inner wall 103 of the outer shell, and adds a limiting block that can abut against the limiting stop bar to the outer edge of the chassis 5. The limiting stop bar is integrally formed with the chassis 5. When the chassis 5 rotates to the point where the limiting block abuts against the limiting stop bar, the chassis 5 cannot rotate. After the device has been tested 7 times, it can no longer be tested. At this time, there is no need for the terminal device to record the number of disassemblies. The 8 times (including the 0th time, i.e., during assembly) correspond to different output values. At the same time, the signal conversion PCB6 is replaced with a Gray code digital encoder conversion PCB, and multiple output contacts 602 are distributed from the inside to the outside in a concentric circle with the OUT contact 601 as the center. Figure 13 As shown, in this output mode, the output contact 602 changes to Gray code inverse code format and outputs a digital signal.

[0028] like Figure 9 , Figure 13 As shown, output contact 602 transforms into three fan-shaped sections from the inside out, corresponding to OUT1, OUT2, and OUT3 respectively. Output contact 602 corresponds to the TOUCH pin. When the metal conductive plate 503 conducts different pins, OUT1, OUT2, and OUT3 output the corresponding Gray code inverse. The output correspondence table is as follows: Figure 14 As shown, each state has one and only one value, and the number of times the device has been disassembled can be obtained simply by reading the output value through the terminal device's main control.

[0029] By changing the overall proportions of the aforementioned pseudo-ejector OUT contact type terminal device disassembly counting device, it is easier to disassemble the counting device to suit terminal devices of different thicknesses, such as the terminal device's packaging box. Simply leading out the output contact 602 via pins allows verification of whether the terminal device is a resealed device without disassembling the packaging box. Additionally, the push rod 2 can be made of transparent material, and an additional layer can be added to the top surface of the middle rod 3, such as... Figure 5 The rotation indicator marks shown allow for direct visual inspection of the number of times the terminal device has been disassembled.

[0030] The pseudo-pin OUT contact type terminal device disassembly counting device of the present invention has a compact structure, is easy to manufacture and has low cost. Through mechanical structure and conversion PCB6 circuit and simple software algorithm, it can realize the terminal device disassembly counting function in the power-off state without power supply, ensuring the safety of terminal device. It supports digital / analog output and has strong adaptability.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for disassembling and counting pseudo-ejector contact terminal equipment, characterized in that: The device includes a housing (1), a pressing mechanism, a chassis (5), and a signal conversion PCB (6). The pressing mechanism is installed on the top of the housing (1) and can move back and forth in the vertical direction. The signal conversion PCB (6) is fixed to the bottom of the housing (1). The chassis (5) is located on the top of the signal conversion PCB (6) and connected to the pressing mechanism. Each time the pressing mechanism moves back and forth, it can drive the chassis (5) to rotate once around the center of the chassis (5). The bottom surface of the chassis (5) is provided with a metal conductive sheet (503). The top surface of the signal conversion PCB (6) is provided with an OUT contact (601) and multiple output contacts (602). The metal conductive sheet (503) rotates with the chassis (5) to connect the OUT contact (601) and multiple output contacts (602) in sequence.

2. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 1, characterized in that: The pushing mechanism includes a push rod (2), a middle rod (3), and a spring (4). A cylindrical through hole is provided in the middle of the outer shell (1) in the vertical direction. The bottom of the push rod (2) passes through the top of the through hole and can move in the vertical direction. The middle rod (3) and the spring (4) are arranged in the through hole from top to bottom. The bottom of the push rod (2) is open and the top of the middle rod (3) rotates through the bottom of the push rod (2). The two ends of the spring (4) are fixed to the middle rod (3) and the base plate (5) respectively. The inner wall of the outer shell (1) surrounds the center line of the through hole. Multiple guide slopes (101) are evenly provided, and the multiple guide slopes (101) are connected end to end in sequence. The bottom of the push rod (2) is provided with a ratchet in the shape of a sawtooth. The bottom of the outer wall of the middle rod (3) is provided with a sloping wall protrusion (301). When the push rod (2) moves vertically downward, the ratchet pushes the sloping wall protrusion (301) to move vertically downward along the guide slope (101). When the push rod (2) moves vertically upward, the spring (4) pushes the sloping wall protrusion (301) to rotate spirally upward along the guide slope (101).

3. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 2, characterized in that: The inner wall of the outer shell (1) is uniformly provided with multiple vertical straight guide grooves (102) around the center line of the through hole, and the outer wall of the push rod (2) is provided with guide protrusions (204) that are slidably connected to the straight guide grooves (102) one by one.

4. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 2, characterized in that: The ratchet includes a first tooth inclined surface (205) and a second tooth inclined surface (206) spaced apart. When the push rod (2) moves back and forth, the top of the inclined wall protrusion (301) slides along the first tooth inclined surface (205) and the second tooth inclined surface (206) in sequence.

5. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 1, characterized in that: The bottom inner wall of the outer casing (1) is provided with a limiting protrusion (104), and the outer edge of the signal conversion PCB (6) is provided with a limiting groove that engages with the limiting protrusion (104).

6. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 1, characterized in that: The signal conversion PCB (6) is an analog signal conversion PCB, with multiple output contacts (602) arranged in a circular array centered on the OUT contact (601).

7. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 1, characterized in that: The signal conversion PCB (6) is a Gray code digital encoder conversion PCB. Multiple output contacts (602) are distributed from the inside to the outside in a concentric circle with the OUT contact (601) as the center.

8. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 2, characterized in that: The inner wall of the outer shell (1) is provided with a limiting stop bar, and the outer edge of the chassis (5) is provided with a limiting block that can abut against the limiting stop bar.

9. The device for disassembling and counting pseudo-pin contact terminal equipment according to claim 2, characterized in that: The bottom surface of the middle rod (3) is provided with a base groove (304), the bottom of the base groove (304) is provided with a first spring groove (303), the top surface of the chassis (5) is provided with a second spring groove (501), and the two ends of the spring (4) are respectively fixed in the first spring groove (303) and the second spring groove (501).

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