A circuit mainboard solder joint detection and repair device

Abstract

The present invention discloses a circuit mainboard solder joint detection and repair device, which belongs to the field of solder joint detection technology, and comprises a detection base, a detection top plate is arranged above the detection base, a plurality of pin sockets are evenly opened inside the detection top plate, a pin plug is slidably arranged inside the pin socket, a master control solenoid valve is arranged on the pin plug, the bottom end of the pin plug passes through the pin socket and is fixedly connected with a shaping cover, and the top end of the pin plug is fixedly connected with a hollow repair plate. The present invention is provided with a detection top plate and a current sensor, and the pins on the circuit board to be tested are inserted into the pin plugs on the detection top plate to achieve electrical connection between the circuit board to be tested and the detection top plate, and the current sensor on the detection top plate is used to monitor the current of each functional module inside the electronic components on the circuit board. If the circuit board solder joint has a bridging phenomenon, the current monitored by the current sensor will increase significantly, thereby achieving the automatic detection function of the circuit board solder joint bridging phenomenon.

Description

Technical Field

[0001] The present invention relates to the technical field of solder joint detection and repair, and in particular to a solder joint detection and repair device for a circuit mainboard. Background Art

[0002] Wave soldering is a commonly used soldering method for circuit boards. Wave soldering achieves the purpose of soldering by directly contacting the soldering surface of the plug-in board with high-temperature liquid tin. During the wave soldering process, bridging is a common problem in wave soldering joints. Bridging refers to the solder tin mistakenly connecting two or more adjacent pads and contacting between the pads to form a conductive path, thereby causing a short circuit in the electronic components on the circuit board. Therefore, after the short-circuit board is soldered, it is necessary to detect whether there is a bridging phenomenon in its solder joints. The existing detection methods are mostly visual inspection and touch inspection. Since there are a large number of solder joints on the short-circuit board, the inspection efficiency is low when inspected by the above methods. In addition, when the bridging phenomenon is detected, it needs to be repaired. The common repair method is to heat the bridge to make the tin at the bridge re-melt and re-solder the solder joint at the bridge. The existing circuit board bridge detection and repair are performed separately and independently, and each bridge needs to be repaired one by one, and the repair efficiency is low. Therefore, a circuit board solder joint detection and repair device is proposed to solve the above problems. Summary of the invention

[0003] The purpose of the present invention is to solve the problems in the prior art that the bridge joints of circuit boards mainly rely on manual visual inspection and touch inspection, which has low inspection efficiency, and the existing circuit board bridge joints need to be repaired one by one and the repair is troublesome, and a circuit board solder joint detection and repair device is proposed.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A circuit mainboard solder joint detection and repair device comprises a detection base, a detection top plate is arranged above the detection base, a plurality of pin plug holes are evenly opened inside the detection top plate, a pin plug is slidably arranged inside the pin plug hole, a master control solenoid valve is arranged on the pin plug, the bottom end of the pin plug passes through the pin plug hole and is fixedly connected with a shaping cover, the top end of the pin plug is fixedly connected with a hollow repair plate, the top end of the detection top plate is fixedly connected with a mounting frame plate around a plurality of pin plug tubes, a plurality of current sensors are installed on the side wall of the mounting frame plate, a docking enclosure is fixedly connected to the bottom end of the detection top plate, a grid heating plate is slidably arranged on the inner side wall of the docking enclosure, a partition cylinder connected to the grid heating plate is installed on the top end of the detection top plate, the grid heating plate is densely covered with grid holes corresponding to the pin plug holes one by one, an electric heating resistance wire is arranged inside the grid heating plate, the shaping cover is arranged on the inner side of the mesh of the grid heating plate, and the edge of the shaping cover contacts the inner wall of the mesh of the grid heating plate;

[0006] A connection port is provided at the connection between the bottom end of the hollow repair plate and the pin insert, a heat flow pipe connected to an external air intake device is fixedly connected to the top end of the hollow repair plate, and a tin liquid pipeline assembly is arranged inside the hollow repair plate.

[0007] Preferably, nut blocks are fixedly connected to the four corners of the detection top plate, and lifting screws are rotatably connected to the four corners of the detection base. The lifting screws are threadedly connected to the nut blocks, and a lifting motor connected to the lifting screws is provided at the bottom end of the detection base.

[0008] Preferably, the surface of the detection top plate is provided with a circuit diagram identical to that of the target circuit board, the pin jacks correspond one-to-one with the welding holes on the target circuit board, and a power socket for connecting electricity is installed at the bottom end of the detection top plate.

[0009] Preferably, the inner wall of the pin insert is fixedly connected with two oppositely arranged electrical copper sheets, the interior of the pin socket is provided with an electrode sheet connected with the circuit diagram, and the outer side wall of the pin insert is in electrical contact with the electrode sheet.

[0010] Preferably, the tin liquid pipeline assembly includes a grid-shaped tin liquid flow guide pipe, the bottom end of the tin liquid flow guide pipe is fixedly connected to an air guide pipe connected to the connecting port, the side wall of the air guide pipe is provided with circumferentially distributed air inlet holes, and the side wall of the air guide pipe is provided with a diversion solenoid valve above the air inlet holes.

[0011] Preferably, an injection pipe for injecting molten tin is fixedly connected to the side wall of the molten tin guide pipe.

[0012] Preferably, an L-shaped plate is installed on the top of the detection top plate, a docking cylinder is installed on the top of the L-shaped plate, and the output end of the docking cylinder is fixedly connected to the hollow repair plate.

[0013] Preferably, a fixed frame is fixedly connected to the top of the detection base, an opening is formed on the side wall of the fixed frame, a clamping plate is slidably provided on the inner wall of the opening, and a clamping cylinder connected to the clamping plate is installed on the top of the detection base.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] 1. This scheme is provided with a detection top plate, a mounting frame plate, a current sensor and a controller. The pins on the circuit board to be tested are inserted into the pin inserts on the detection top plate to achieve electrical connection between the circuit board to be tested and the detection top plate. The current sensor on the detection top plate is used to monitor the current of each functional module inside the electronic components on the circuit board. If the circuit board solder joints are bridged, the current monitored by the current sensor will increase significantly, thereby realizing the automatic detection function of the circuit board solder joint bridge phenomenon.

[0016] 2. This solution is provided with a heat flow tube, a grid heating plate, a shaping cover and a tin liquid guide tube. The grid heating plate is used to melt the tin at the bridge, which preliminarily solves the bridging phenomenon. Then, the heat flow tube is used to introduce a hot air flow, and the hot air flow is used to heat melt the original solder joints. At the same time, the shaping cover is used to seal the pin solder joints, and the tin liquid guide tube is used to inject tin liquid into the inside of the shaping cover to achieve the re-soldering function of the pins. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a three-dimensional structural schematic diagram of a circuit mainboard solder joint detection and repair device proposed by the present invention;

[0018] Figure 2 A schematic diagram of the assembly structure of a circuit board solder joint detection and repair device proposed by the present invention Figure 1 ;

[0019] Figure 3 A schematic diagram of the assembly structure of a circuit board solder joint detection and repair device proposed by the present invention Figure 2 ;

[0020] Figure 4 A schematic diagram of the assembly structure of a circuit board solder joint detection and repair device proposed by the present invention Figure 3 ;

[0021] Figure 5 This is a schematic cross-sectional structure diagram of an installation frame plate and a pin insert in a circuit mainboard solder joint detection and repair device proposed by the present invention;

[0022] Figure 6 for Figure 5 The enlarged structural diagram at A in the middle;

[0023] Figure 7 This is a structural schematic diagram of a tin liquid guide tube and a hollow repair plate in a circuit mainboard solder joint detection and repair device proposed by the present invention;

[0024] Figure 8 for Figure 7 Enlarged structural diagram at B in the middle.

[0025] In the figure: 1. Detection base; 2. Lifting motor; 3. Fixed frame; 4. Clamping cylinder; 5. Clamping plate; 6. Detection top plate; 601. Pin jack; 7. Docking cylinder; 8. Hollow repair plate; 801. Connection port; 9. Heat flow pipe; 10. Partition cylinder; 11. Lifting screw rod; 12. Mounting frame plate; 13. Pin plug; 14. Grid heating plate; 15. Shaping cover; 16. Docking enclosure; 17. Power socket; 18. Master control solenoid valve; 19. Current sensor; 20. Power copper sheet; 21. Tin liquid guide tube; 22. Air guide tube; 2201. Air inlet; 23. Diverter solenoid valve; 24. Injection pipe. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the 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 position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] Example, see Figures 1 to 8 A circuit mainboard solder joint detection and repair device comprises a detection base 1, a detection top plate 6 is arranged above the detection base 1, a plurality of pin sockets 601 are evenly arranged inside the detection top plate 6, a pin insert tube 13 is slidably arranged inside the pin socket 601, further, a circuit diagram identical to that of a target circuit board is arranged on the surface of the detection top plate 6, the pin sockets 601 correspond one-to-one with the welding holes on the target circuit board, a power socket 17 for connecting electricity to the surface circuit thereof is installed at the bottom end of the detection top plate 6, further, two relatively arranged power connection copper sheets 20 are fixedly connected to the inner wall of the pin insert tube 13, an electrode sheet connected to the circuit diagram is arranged inside the pin socket 601, and the outer wall of the pin insert tube 13 is in electrical contact with the electrode sheet.

[0030] It should be noted that: the pins of the electronic components on the circuit board to be tested are plugged into the pin insert 13, and the arc-shaped copper sheet 20 has a clamping force on the pins to ensure the stability of the plugging between the pins and the pin insert 13;

[0031] The arrangement of the electrode sheet realizes the electrical connection function between the pin insert 13 and the circuit diagram, and the arrangement of the power socket 17 facilitates the detection of the connection between the top plate 6 and the external power supply.

[0032] The pin plug 13 is provided with a master control solenoid valve 18, the bottom end of the pin plug 13 passes through the pin plug hole 601 and is fixedly connected to the shaping cover 15, the top end of the pin plug 13 is fixedly connected to the hollow repair plate 8, the bottom end of the hollow repair plate 8 and the connection between the pin plug 13 are provided with a connection port 801, and the top end of the hollow repair plate 8 is fixedly connected to the heat flow pipe 9 connected to the external air intake device;

[0033] It should be noted that the electric air heater can heat the air from the initial temperature to the required temperature, up to 850°C, and this heater has been widely used in many fields. The melting point of tin is 231.89°C to 232°C, so the heated air can melt the solder joint.

[0034] It should be noted that: the external air intake equipment fills hot gas into the inner side of the hollow repair plate 8 through the heat flow pipe 9, which is used to heat and melt the solder joints at the pins. The setting of the shaping cover 15 can shape the molten tin liquid and prevent the tin liquid from flowing around.

[0035] The top end of the detection top plate 6 is fixedly connected to a mounting frame plate 12 around a plurality of pin inserts 13 , and a plurality of current sensors 19 are mounted on the side walls of the mounting frame plate 12 .

[0036] It should be noted that: taking the electronic components as units, each electronic component has a plurality of pins, each pin corresponds to a pin insert 13, and each electronic component corresponds to a mounting frame plate 12;

[0037] Each electronic component is provided with a plurality of functional modules inside, and each functional module is connected with a corresponding pin. The current sensor 19 is used to detect the current of each functional module. When two or more pins are bridged, the corresponding functional module will be short-circuited, and the current value monitored by the current sensor 19 used to monitor the functional module will be greater than the normal value. At this time, the current sensor 19 will provide feedback to the controller.

[0038] The bottom end of the detection top plate 6 is fixedly connected with a docking panel 16, and the inner side wall of the docking panel 16 is slidably provided with a grid heating plate 14. The top end of the detection top plate 6 is provided with a partition cylinder 10 connected with the grid heating plate 14. The grid heating plate 14 is densely covered with grid holes corresponding to the pin sockets 601 one by one. The inside of the grid heating plate 14 is provided with an electric heating resistance wire. The shaping cover 15 is provided inside the mesh of the grid heating plate 14, and the edge of the shaping cover 15 is in contact with the inner wall of the mesh of the grid heating plate 14.

[0039] It should be noted that the setting of the electric heating resistance wire heats the grid heating plate 14, and the grid heating plate 14 is driven downward by the partition cylinder 10. The grid heating plate 14 can contact and melt the tin at the bridge, thereby realizing the cutting function of the tin at the bridge.

[0040] A tin liquid pipeline assembly is arranged inside the hollow repair plate 8. Furthermore, the tin liquid pipeline assembly includes a grid-shaped tin liquid guide tube 21. The bottom end of the tin liquid guide tube 21 is fixedly connected to an air guide tube 22 connected to the connecting port 801. The side wall of the air guide tube 22 is provided with circumferentially distributed air inlet holes 2201. The side wall of the air guide tube 22 is located above the air inlet holes 2201 and is provided with a diversion solenoid valve 23. Furthermore, an injection tube 24 for injecting tin liquid is fixedly connected to the side wall of the tin liquid guide tube 21.

[0041] It should be noted that: the surfaces of the tin liquid guide tube 21 and the air guide tube 22 are both provided with an insulation layer; tin liquid is injected into the tin liquid guide tube 21 through the injection tube 24, and the diversion solenoid valve 23 at the solder joint that needs to be repaired can be opened through the controller, so that the tin liquid flows into the shaping cover 15 through the air guide tube 22, and then contacts the solder joint of the pin, thereby realizing the pin re-soldering function.

[0042] Furthermore, nut blocks are fixedly connected at the four corners of the detection top plate 6, and lifting screw rods 11 are rotatably connected at the four corners of the detection base 1. The lifting screw rod 11 is threadedly connected to the nut blocks, and a lifting motor 2 connected to the lifting screw rod 11 is provided at the bottom end of the detection base 1.

[0043] It should be noted that the lifting motor 2 drives the lifting screw 11 to rotate, and with the cooperation of the nut block, the detection top plate 6 moves downward, so that the pins of the electronic components on the circuit board to be tested can be inserted into the pin insertion tube 13.

[0044] Furthermore, an L-shaped plate is installed on the top of the detection top plate 6 , and a docking cylinder 7 is installed on the top of the L-shaped plate. The output end of the docking cylinder 7 is fixedly connected to the hollow repair plate 8 .

[0045] It should be noted that: the docking cylinder 7 drives the hollow repair plate 8 to move downward, the hollow repair plate 8 drives the pin insert 13 to move downward, and the pin insert 13 drives the shaping cover 15 to move downward, so that the shaping cover 15 contacts the current plate, realizing the covering function of the pin, which is convenient for shaping the molten tin liquid, avoiding the flow of the tin liquid, ensuring the pin welding while ensuring the aesthetics of the solder joint.

[0046] Furthermore, a fixed frame 3 is fixedly connected to the top of the detection base 1, an opening is formed on the side wall of the fixed frame 3, a clamping plate 5 is slidably provided on the inner wall of the opening, and a clamping cylinder 4 connected to the clamping plate 5 is installed on the top of the detection base 1.

[0047] It should be noted that the circuit board to be tested is placed inside the fixed frame 3 with the pins facing upward.

[0048] It should be noted that the surfaces of the structures in the device that are in contact with the tin liquid are all provided with a polytetrafluoroethylene coating to prevent the tin liquid from adhering.

[0049] When the present invention is used, the circuit board to be tested is placed inside the fixed frame 3, with the pins facing upward, and then the clamping cylinder 4 is turned on, the clamping cylinder 4 drives the clamping plate 5 to move, and the clamping plate 5 cooperates with the side wall of the fixed frame 3 to achieve the clamping and fixing function of the circuit board to be tested, and then the lifting motor 2 is turned on, and the lifting motor 2 drives the lifting screw 11 to rotate, and with the cooperation of the nut block, the detection top plate 6 moves downward, so that the pins of the electronic components on the circuit board to be tested can be inserted into the pin plug 13, and under the action of the pin plug 13 and the power connection copper sheet 20, the pins realize the electrical connection function of the circuit diagram on the detection top plate 6, and then the external power supply can be powered on the detection top plate 6 through the power connection socket 17;

[0050] After the detection top plate 6 is powered on, the current sensor 19 installed on the frame plate 12 can monitor the current value flowing inside each electronic component. When a bridge phenomenon occurs at the pin solder joint on the electronic component, the corresponding functional module inside the electronic component is short-circuited. At this time, the current value monitored by the current sensor 19 used to monitor the functional module is greater than the normal value. At this time, the current sensor 19 feeds back a signal to the controller, and the controller controls the partition cylinder 10 to work. The partition cylinder 10 drives the grid heating plate 14 to move downward, so that the grid heating plate 14 contacts the tin at the bridge, and the electric heating resistance wire inside the grid heating plate 14 is used to fuse the tin at the bridge (when the grid heating plate 14 contacts the circuit board, the controller turns off the electric heating resistance wire). ), and at the same time, an external air intake device is used to inject hot air flow into the hollow repair plate 8 through the heat flow pipe 9 (at the same time, the controller opens the main hole solenoid valve at the pin plug 13 at the solder joint to be repaired), and the hot air flow enters the air guide tube 22 through the air intake hole 2201 on the surface of the air guide tube 22, and then enters the pin plug 13 through the air guide tube 22, and finally enters the plastic cover 15 through the pin plug 13, so that the solder joint can be heated and melted. At the same time, the controller controls the docking cylinder 7 to open, and the docking cylinder 7 controls the hollow repair plate 8 to move downward, and the hollow repair plate 8 drives the pin plug 13 to move downward, and the pin plug 13 drives the plastic cover 15 to move downward until the plastic cover 15 contacts the circuit board. At this time, the plastic cover 15 plays a role of sealing the solder joint of the pin;

[0051] Afterwards, the controller controls the shunt solenoid valve 23 on the air guide tube 22 at the pin to open at a fixed time, so that the tin liquid inside the tin liquid guide tube 21 enters the pin insert tube 13 through the air guide tube 22, and then enters the shaping cover 15 and contacts the pin (the dripping amount of the tin liquid is determined by the timing opening time of the shunt solenoid valve 23), realizing the re-welding function of the pin, and after the tin liquid is cooled and solidified (the tin liquid that can enter the shaping cover 15 is shaped and limited to prevent the tin liquid from flowing around, thereby ensuring the welding function of the tin liquid on the pin, and at the same time ensuring the aesthetics of the solder joint formed after the tin liquid solidifies), that is, after the repair operation is completed, the power supply to the detection top plate 6 is disconnected, and the controller controls the lifting motor 2 to work after accommodating, so that the detection top plate 6 moves up and resets, at this time, the pin is separated from the pin insert tube 13, and finally the clamping cylinder 4 is controlled to work to separate the clamping plate 5 from the circuit board, and the repaired circuit board can be taken out from the inner side of the fixed frame 3;

[0052] After the detection top plate 6 is reset, hot air flow can be continuously introduced into the hollow repair plate 8 through the heat flow pipe 9, so that the hot air flow continuously enters the air duct 22 and the pin insert 13, which can melt a small amount of solidified tin liquid inside the air duct 22 and the pin insert 13 and blow it out, thereby realizing the self-cleaning function of the air duct 22 and the pin insert 13, which is convenient for subsequent reuse.

[0053] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A circuit board solder joint detection and repair device, comprising a detection base (1), characterized in that: A detection top plate (6) is arranged above the detection base (1), a plurality of pin insertion holes (601) are evenly arranged inside the detection top plate (6), a pin insertion tube (13) is slidably arranged inside the pin insertion hole (601), a master control solenoid valve (18) is arranged on the pin insertion tube (13), the bottom end of the pin insertion tube (13) passes through the pin insertion hole (601) and is fixedly connected to a shaping cover (15), the top end of the pin insertion tube (13) is fixedly connected to a hollow repair plate (8), the top end of the detection top plate (6) is fixedly connected to a mounting frame plate (12) around the plurality of pin insertion tubes (13), and a side wall of the mounting frame plate (12) is provided. A plurality of current sensors (19) are installed, the bottom end of the detection top plate (6) is fixedly connected to a docking panel (16), a mesh heating plate (14) is slidably provided on the inner side wall of the docking panel (16), a partition cylinder (10) connected to the mesh heating plate (14) is installed on the top end of the detection top plate (6), the mesh heating plate (14) is densely covered with mesh holes corresponding to the pin sockets (601) one by one, an electric heating resistance wire is provided inside the mesh heating plate (14), the shaping cover (15) is provided inside the mesh of the mesh heating plate (14), and the edge of the shaping cover (15) is in contact with the inner wall of the mesh of the mesh heating plate (14); A connection port (801) is provided at the connection between the bottom end of the hollow repair plate (8) and the pin insert (13); a heat flow pipe (9) connected to an external air intake device is fixedly connected to the top end of the hollow repair plate (8); and a tin liquid pipeline assembly is provided inside the hollow repair plate (8).

2. A circuit mainboard solder joint detection and repair device according to claim 1, characterized in that: Nut blocks are fixedly connected at the four corners of the detection top plate (6), lifting screw rods (11) are rotatably connected at the four corners of the detection base (1), the lifting screw rods (11) are threadedly connected to the nut blocks, and a lifting motor (2) connected to the lifting screw rods (11) is provided at the bottom end of the detection base (1).

3. A circuit mainboard solder joint detection and repair device according to claim 1, characterized in that: The surface of the detection top plate (6) is provided with a circuit diagram identical to that of the target circuit board, the pin sockets (601) correspond one-to-one with the welding holes on the target circuit board, and the bottom end of the detection top plate (6) is provided with a power socket (17) for connecting electricity.

4. A circuit mainboard solder joint detection and repair device according to claim 1, characterized in that: The inner wall of the pin insert (13) is fixedly connected to two oppositely arranged electrical copper sheets (20), an electrode sheet connected to the circuit diagram is arranged inside the pin insertion hole (601), and the outer wall of the pin insert (13) is in electrical contact with the electrode sheet.

5. A circuit mainboard solder joint detection and repair device according to claim 1, characterized in that: The tin liquid pipeline assembly comprises a grid-shaped tin liquid flow guide tube (21); the bottom end of the tin liquid flow guide tube (21) is fixedly connected to an air guide tube (22) connected to the connection port (801); a side wall of the air guide tube (22) is provided with circumferentially distributed air inlet holes (2201); and a diversion solenoid valve (23) is provided on the side wall of the air guide tube (22) above the air inlet holes (2201).

6. A circuit mainboard solder joint detection and repair device according to claim 5, characterized in that: An injection pipe (24) for injecting tin liquid is fixedly connected to the side wall of the tin liquid guide pipe (21).

7. A circuit mainboard solder joint detection and repair device according to claim 1, characterized in that: An L-shaped plate is installed at the top end of the detection top plate (6), a docking cylinder (7) is installed at the top end of the L-shaped plate, and an output end of the docking cylinder (7) is fixedly connected to a hollow repair plate (8).

8. The circuit board solder joint detection and repair device according to claim 1, characterized in that: The top of the detection base (1) is fixedly connected to a fixed frame (3), a side wall of the fixed frame (3) is provided with an opening, a clamping plate (5) is slidably provided on the inner wall of the opening, and a clamping cylinder (4) connected to the clamping plate (5) is installed at the top of the detection base (1).

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