CBCT (cone beam computed tomography) turnover support

Abstract

The invention discloses a CBCT turnover support which comprises a fixed module and a movable module. The CBCT support has four degrees of freedom of translation in the X direction, the Y direction and the Z direction and rotation around the Y direction, has multiple adjusting functions, and can meet actual requirements, especially use requirements of Flash radiotherapy equipment with a treatment head far away from a roller rack. Moreover, the support can be fully unfolded during working and folded and stored in a non-working state, and has good adjusting performance and storage and unfolding performance.

Description

Technical Field

[0001] The present invention relates to the field of tomography, and more specifically, to a CBCT flip bracket. Background Art

[0002] CBCT, or cone beam computed tomography, is a medical imaging technology currently widely used in radiotherapy. This technology mainly uses an X-ray source to rotate around the patient, capture images at different angles, and then use these images to reconstruct three-dimensional tomographic images. Since CBCT uses cone beam X-rays rather than fan beams, high-resolution 3D real-time images can be obtained in a shorter scanning time.

[0003] In the prior art, a bracket is usually used to set the flat-panel detector in the CBCT on the radiotherapy equipment. For example, the CBCT mounting bracket on the equipment of Elekta, Varian, etc. is directly rotatably mounted on the frame. This type of bracket can be used on traditional radiotherapy equipment, but cannot be directly applied to Flash-type radiotherapy equipment, because the treatment head of Flash-type radiotherapy equipment is longer and closer to the treatment bed than conventional equipment, and the adjustment accuracy requirements are higher. Moreover, Flash-type radiotherapy equipment also has full-field and half-field requirements. The CBCT bracket on the traditional radiotherapy equipment is too simple in movement function and can only be rotated and adjusted in a certain direction or cannot be adjusted. Especially when the radiation field needs to be adjusted, the lack of adjustment direction makes it difficult to adjust and it is difficult to meet actual needs. Summary of the invention

[0004] The present invention overcomes the deficiency of the prior art in adjusting direction and provides a CBCT flip bracket, so as to solve the problem of insufficient adjusting direction in the prior art.

[0005] In order to solve the above technical problems, one embodiment of the present invention adopts the following technical solution:

[0006] A CBCT flip bracket, comprising a fixed module and a movable module;

[0007] The fixing module comprises a fixing plate;

[0008] The mobile module includes a column, a rotating mounting assembly, a rotating power device, a sliding mounting assembly, and a detector mounting plate;

[0009] The column is installed on the fixed module;

[0010] The rotating mounting assembly includes a rotating mounting plate and a first sliding assembly; the rotating mounting plate is rotatably connected to the column, the rotating power device is installed on the rotating mounting plate, and the rotating power device drives the rotating mounting plate to rotate; the first sliding assembly is installed on the rotating mounting plate;

[0011] The sliding mounting assembly comprises a sliding mounting plate and a second sliding assembly, wherein the sliding mounting plate is mounted on the first sliding assembly, and the first sliding assembly can drive the sliding mounting assembly to move; the second sliding assembly is mounted on the sliding mounting plate, and the second sliding assembly is arranged orthogonally to the first sliding assembly;

[0012] The detector mounting plate is mounted on the second sliding assembly, and the second sliding assembly can drive the detector mounting plate to move perpendicularly to the sliding direction of the first sliding assembly.

[0013] When in use, the flat panel detector is mounted on the detector mounting plate.

[0014] The fixing plate is installed on the frame of the radiotherapy equipment. Before use, the mounting plate is rotated to be parallel to the fixing plate, which occupies little space.

[0015] When in use, the rotating mounting plate is rotated 90°, and after the rotation, the sliding mounting plate can slide on the rotating mounting plate to complete the position adjustment in one direction; the detector mounting plate and the flat-panel detector installed on it can further slide on the sliding mounting plate to complete the position adjustment in the vertical direction. In other words, folding and position adjustment in two vertical directions can be achieved.

[0016] A further technical solution is that the fixing module includes a third sliding component, and the third sliding component is installed on the fixing plate;

[0017] The column is installed on the third sliding assembly, and the third sliding assembly can drive the column to move.

[0018] When the column slides along the fixed plate, the entire mobile module can move in the third direction, that is, the detector mounting plate can be adjusted in the front-to-back, up-down, left-to-right directions.

[0019] A further technical solution is that the first sliding assembly includes a first guide rail, a first slider, and a first driving assembly, the first guide rail is mounted on the rotating mounting plate, the first slider is mounted on the first guide rail, the sliding mounting plate is mounted on the first slider, the first driving assembly is mounted between the rotating mounting plate and the sliding mounting plate, and the first driving assembly drives the sliding mounting plate to move along the direction of the first guide rail;

[0020] The second sliding assembly includes a second guide rail, a second slider, and a second driving assembly. The second guide rail is mounted on the sliding mounting plate. The second slider is mounted on the second guide rail. The detector mounting plate is mounted on the second slider. The second driving assembly is mounted between the sliding mounting plate and the detector mounting plate. The second driving assembly drives the detector mounting plate to move along the direction of the second guide rail.

[0021] The third sliding assembly includes a third guide rail, a third slider, a movable plate, and a third driving assembly. The third guide rail is installed on a fixed plate, the third slider is installed on the third guide rail, the movable plate is installed on the third slider, the column is installed on the movable plate, and the third driving assembly is installed between the fixed plate and the movable plate. The third driving assembly drives the movable plate to move along the direction of the third guide rail.

[0022] Through the cooperation of the guide rail, the slider and the driving assembly, the sliding of the movable plate, the sliding mounting plate and the detector mounting plate can be restricted and supported by the guide rail, thereby improving the control accuracy.

[0023] A further technical solution is that the number of the first guide rail, the second guide rail and the third guide rail is two.

[0024] A further technical solution is that the first sliding assembly includes a first limiting device, which is installed on the first guide rail to limit the sliding range of the first sliding block;

[0025] The second sliding assembly includes a second limiting device, which is installed on the second guide rail to limit the sliding range of the second sliding block;

[0026] The third sliding assembly includes a third limiting device, which is installed on the third guide rail to limit the sliding range of the third sliding block.

[0027] A further technical solution is that the first driving assembly includes a driving motor, a transmission assembly, a screw support seat, a ball screw, and a nut seat;

[0028] The ball screw is mounted on the screw support seat, the nut seat is mounted on the ball screw, and the transmission assembly is connected to the drive motor and the ball screw;

[0029] The second drive assembly and the third drive assembly have the same structure as the first drive assembly.

[0030] A further technical solution is to include a rotation limiting device, wherein the rotation limiting device is installed between the column and the rotation mounting plate;

[0031] The rotation limiting device limits the rotation angle of the rotating mounting plate to 90°.

[0032] Since the flat panel detector only needs to have two states, working and folded, when in use, the state switching can be achieved by simply flipping within a range of 90°.

[0033] A further technical solution is that the rotation limit device includes a rotation limit block, a rotation shaft, and a limit block mounting seat;

[0034] The rotating shaft is arranged between the column and the rotating mounting plate, the rotating limit block is sleeved on the rotating shaft, and the rotating limit block and the rotating shaft are fixedly connected;

[0035] The outer surface of the rotation limit block is composed of two continuous surfaces, one of which is a limit surface, and the limit surface includes a 90° arc surface and a plane extending in the tangent direction of the 90° arc surface;

[0036] The limit block mounting seat is arranged on the rotating mounting plate, the rotating shaft passes through the limit block mounting seat, and the limit surface of the rotating limit block abuts against the plane of the rotating mounting plate.

[0037] A further technical solution is that the rotation limiting device includes a rotation shaft, an angle indicating rod, a limiting rod mounting plate, a first angle limiting rod, and a second angle limiting rod;

[0038] The rotating shaft is arranged between the column and the rotating mounting plate, and the angle indicating rod is installed at the end of the rotating shaft. When the rotating shaft rotates, the angle indicating rod rotates together;

[0039] The first angle limiting rod and the second angle limiting rod are installed on the limiting rod installation plate, and the first angle limiting rod, the second angle limiting rod and the axis of the second rotating shaft form an angle of 90°;

[0040] When the angle indicating rod contacts the first angle limiting rod and the second angle limiting rod, the rotation angle is limited.

[0041] Compared with the prior art, the present invention has at least the following beneficial effects: the CBCT bracket provided by the present invention has translation in the three directions of X, Y, and Z, and rotation around the Y direction, with a total of 4 degrees of freedom, and has multiple adjustment functions, and cooperates with the rotation limit device to meet actual needs, especially for such Flash radiotherapy equipment where the treatment head is far away from the roller frame. The bracket can be fully unfolded when working and folded and stored when not working. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the partially unfolded structure of the CBCT flip bracket;

[0043] Figure 2 is a first schematic diagram of a fixed module structure;

[0044] Figure 3 is a second schematic diagram of a fixed module structure;

[0045] Figure 4 It is a schematic diagram of the structure of the column and the rotating installation assembly;

[0046] Figure 5 This is a schematic diagram of the partially unfolded structure of the CBCT flip bracket;

[0047] Figure 6 It is a schematic diagram of the structure of the sliding installation component;

[0048] Figure 7 This is a schematic diagram of the fully unfolded structure of the CBCT flip bracket;

[0049] Figure 8 This is a schematic diagram of the folding structure of the CBCT flip bracket;

[0050] Fig. 9 This is a schematic diagram of the structure of the first set of rotation limiting devices;

[0051] Fig.10 A first schematic diagram of the rotation of the rotation limit block;

[0052] Fig.11 A second schematic diagram of the rotation limit block;

[0053] Fig.12 This is a schematic diagram of the structure of the second set of rotation limiting devices.

[0054] In the figure, 1-fixed module, 11-fixed plate, 12-third sliding assembly, 121-third guide rail, 122-third slider, 123-third limiting device, 124-movable plate, 125-third driving assembly, 1251-driving motor, 1252-transmission assembly, 1253-screw support seat, 1254-ball screw, 1255-nut seat, 2-moving module, 21-column, 22-rotating mounting assembly, 221-rotating mounting plate, 222-first sliding assembly, 2221-first guide rail, 2222-first slider, 2223-first driving assembly, 2224-first limiting device, 23-rotational power device, 231-driving motor, 232-rotational gear, 233-fixed gear, 24-sliding mounting assembly, 241-sliding mounting plate, 242-second sliding assembly, 2421-second guide rail, 2422-second slider, 2423-second driving assembly, 2424-second limiting device, 25-detector mounting plate, 3-rotational limiting device, 31-rotational limiting block, 32-rotational shaft, 33-limiting block mounting seat, 34-keyway, 35-second rotating shaft, 36-angle indicating rod, 37-limiting rod mounting plate, 38-first angle limiting rod, 39-second angle limiting rod. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. 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.

[0056] See also Figure 1-Figure 12, a CBCT flip stand, comprising, a fixed module 1, a moving module 2, and a rotation limiting device 3;

[0057] The fixing module 1 includes a fixing plate 11 and a third sliding assembly 12, and the third sliding assembly 12 is installed on the fixing plate 11;

[0058] The third sliding assembly 12 includes two third guide rails 121, a third slider 122, a movable plate 124, a third driving assembly 125, and a third limiter 123. The third limiter 123 is installed on the third guide rails 121 to limit the sliding range of the third slider 122.

[0059] The third guide rail 121 is installed on the fixed plate 11, the third slider 122 is installed on the third guide rail 121, the movable plate 124 is installed on the third slider 122, the column 21 is installed on the movable plate 124, and the third driving assembly 125 is installed between the fixed plate 11 and the movable plate 124. The third driving assembly 125 drives the movable plate 124 to move along the direction of the third guide rail 121.

[0060] The mobile module 2 includes a column 21, a rotating installation assembly 22, a rotating power device 23, a sliding installation assembly 24, and a detector installation plate 25;

[0061] In this embodiment, the pillar 21 is installed on the movable plate 124 , and the pillar 21 moves with the movable plate 124 .

[0062] The rotating installation assembly 22 includes a rotating installation plate 221 and a first sliding assembly 222; the rotating installation plate 221 is rotatably connected to the column 21, and the rotating power device 23 is installed on the rotating installation plate 221, and the rotating power device 23 drives the rotating installation plate 221 to rotate;

[0063] In this embodiment, the rotating power device 23 includes a driving motor 231, a rotating gear 232, and a fixed gear 233. The output end of the driving motor 231 is connected to the rotating gear 232. The rotating gear 232 and the fixed gear 233 form a gear transmission. The fixed gear 233 is installed on the rotating mounting plate 221, thereby realizing the rotation of the rotating mounting plate 221.

[0064] The first sliding assembly 222 is installed on the rotating mounting plate 221;

[0065] The first sliding assembly 222 includes two first guide rails 2221, a first slider 2222, a first driving assembly 2223, and a first limiting device 2224. The first guide rails 2221 are installed on the rotating mounting plate 221, the first slider 2222 is installed on the first guide rails 2221, and the first limiting device 2224 is installed on the first guide rails 2221 to limit the sliding range of the first slider 2222.

[0066] The sliding mounting assembly 24 includes a sliding mounting plate 241 and a second sliding assembly 242. The sliding mounting plate 241 is mounted on the first sliding assembly 222. Specifically, the sliding mounting plate 241 is mounted on the first slider 2222. The first driving assembly 2223 is installed between the rotating mounting plate 221 and the sliding mounting plate 241. The first driving assembly 2223 drives the sliding mounting plate 241 to move along the first guide rail 2221.

[0067] The second sliding component 242 is installed on the sliding mounting plate 241 ; the second sliding component 242 is arranged orthogonally to the first sliding component 222 .

[0068] The second sliding assembly 242 includes two second guide rails 2421, a second slider 2422, a second driving assembly 2423, and a second limiting device 2424. The second guide rail 2421 is installed on the sliding mounting plate 241, the second slider 2422 is installed on the second guide rail 2421, the detector mounting plate 25 is installed on the second slider 2422, the second driving assembly 2423 is installed between the sliding mounting plate 241 and the detector mounting plate 25, and the second driving assembly 2423 drives the detector mounting plate 25 to move along the second guide rail 2421.

[0069] The second limiting device 2424 is installed on the second guide rail 2421 to limit the sliding range of the second slider 2422;

[0070] The detector mounting plate 25 is mounted on the second sliding assembly 242, and the second sliding assembly 242 can drive the detector mounting plate 25 to move perpendicularly to the sliding direction of the first sliding assembly 222;

[0071] The first drive assembly 2223, the second drive assembly 2423, and the third drive assembly 125 can be controlled by a cylinder, an electric cylinder, a hydraulic rod, or other control devices. In this embodiment, the first drive assembly 222, the second drive assembly 2423, and the third drive assembly 125 have the same structure. Figure 2 , including a driving motor 1251, a transmission assembly 1252, a screw support seat 1253, a ball screw 1254, and a nut seat 1255;

[0072] The ball screw 1254 is installed on the screw support seat 1253, the nut seat 1255 is installed on the ball screw 1254, and the transmission assembly 1252 is connected to the drive motor 1251 and the ball screw 1254;

[0073] The transmission component 1252 can be a belt drive, a chain drive, etc. In this embodiment, the transmission component 1252 is a gear drive.

[0074] See also Fig. 9 The rotation limiting device 3 is installed between the column 21 and the rotation mounting plate 221; it is mainly used to limit the rotation angle of the mobile module 2.

[0075] The rotation limiting device 3 limits the rotation angle of the rotating mounting plate 221 to 90°.

[0076] The rotation limiting device 3 can use a stopper, a rotating connecting rod, etc. to achieve the limiting effect;

[0077] In this embodiment, the rotation limiting device 3 has two sets, which are respectively arranged on two rotating shafts.

[0078] The first set of limiting devices includes a rotation limiting block 31, a first rotation shaft 32, and a limiting block mounting seat 33;

[0079] A fixed gear 233 is provided on the first rotating shaft 32, and the first rotating shaft 32 is provided between the column 21 and the rotating mounting plate 221. The rotating limit block 31 is mounted on the first rotating shaft 32, and the rotating limit block 31 and the first rotating shaft 32 are fixedly connected. Exemplarily, the fixed connection can be achieved by means of a latch connection, a screw connection, a keyway connection, etc.

[0080] In this embodiment, the rotation limit block 31 and the first rotation shaft 32 are connected by a keyway, and the keyway 34 is provided on the limit block 31 .

[0081] The outer surface of the rotation limit block 31 is composed of two continuous surfaces, one of which is a limit surface, and the limit surface includes a 90° arc surface and a plane extending in the tangent direction of the 90° arc surface, see Fig.10 ;

[0082] The limit block mounting seat 33 is arranged on the rotating mounting plate 221, and the rotating limit block 31 is installed in the limit block mounting seat 33. The limit surface of the rotating limit block 31 abuts against the plane of the rotating mounting plate 221. When the plane extending in the tangent direction of the arc surface is rotated to fit the limit block, the rotating limit block 31 completes the limit. Fig.11 .

[0083] The second set of limiting devices includes a second rotating shaft 35, an angle indicating rod 36, a limiting rod mounting plate 37, a first angle limiting rod 38, and a second angle limiting rod 39;

[0084] The second rotating shaft 35 is disposed between another column and the rotating mounting plate 221, and the angle indicating rod 36 is installed at the end of the rotating shaft. When the second rotating shaft 35 rotates, the angle indicating rod 36 rotates together;

[0085] The first angle limiting rod 38 and the second angle limiting rod 39 are installed on the limiting rod installation plate 37, and the first angle limiting rod 38, the second angle limiting rod 39 and the axis of the second rotating shaft 35 form an angle of 90°;

[0086] When the angle indicating rod 36 contacts the first angle limiting rod 38 and the second angle limiting rod 39 , the rotation angle is limited.

[0087] In this embodiment, the first angle limiting rod 38, the second angle limiting rod 39 and the axis of the second installation shaft 35 form a 90° angle to ensure that the rotation of the rotating installation plate 221 is not greater than 90°. When the angle indicating rod 36 moves to the position of the first angle limiting rod 38 or the second angle limiting rod 39, the rotating installation plate 221 stops rotating.

[0088] The specific working process is as follows: when the rotating mounting plate 221 is fully stored, the angle indicator rod 36 is located at the first angle limit rod 38; as the rotating mounting plate 221 is continuously expanded, the angle indicator rod 36 will gradually rotate toward the second angle limit rod 39, and when the angle indicator rod 36 rotates to the second angle limit rod 39, the rotating mounting plate 221 is expanded to the 90° position, at which time the rotating power device 23 stops driving, and the rotating mounting plate 221 does not continue to rotate. Similarly, when the rotating mounting plate 221 is fully expanded to 90°, the angle indicator rod 36 is located at the second angle limit rod 39; as the rotating mounting plate 221 is continuously stored, the angle indicator rod 36 will gradually rotate toward the first angle limit rod 38, and when the angle indicator rod 36 rotates to the first angle limit rod 38, the rotating mounting plate 221 is stored to the 0° position, at which time the rotating power device 23 stops driving, and the rotating mounting plate 221 does not continue to rotate.

[0089] Non-working state Figure 8 When it is to work, first rotate the mobile module 2 to make it perpendicular to the fixed module 1, and then move the mobile module 2 from the left end to the right end; then extend the sliding mounting plate 241 in sequence. If it is full-field irradiation, the detector mounting plate does not move, so that it is directly opposite to the tube beam, and the tube beam is fully irradiated on the flat-panel detector to achieve full-field irradiation. If half-field irradiation is required, the detector mounting plate 25 is adjusted so that only half of the tube beam is irradiated on the flat-panel detector, and half-field irradiation is achieved, see Figure 7 The detector mounting plate 25 can be translated in the Y direction to achieve full-field and half-field irradiation more accurately.

[0090] When adjustment is required in the X direction, the movable plate 124 on the fixed module 1 can drive the moving module 2 to adjust in the X direction.

[0091] Although the present invention is described herein with reference to the illustrative embodiments of the present invention, it should be understood that those skilled in the art can design many other modifications and implementations, which will fall within the scope and spirit of the principles disclosed in the present application. More specifically, within the scope disclosed in the present application, multiple variations and improvements can be made to the components and / or layout of the subject combination layout. In addition to the variations and improvements made to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A CBCT flip stand, characterized in that: Including fixed module and mobile module; The fixing module comprises a fixing plate; The mobile module includes a column, a rotating mounting assembly, a rotating power device, a sliding mounting assembly, and a detector mounting plate; The column is installed on the fixed module; The rotating mounting assembly includes a rotating mounting plate and a first sliding assembly; the rotating mounting plate is rotatably connected to the column, the rotating power device is installed on the rotating mounting plate, and the rotating power device drives the rotating mounting plate to rotate; the first sliding assembly is installed on the rotating mounting plate; The sliding mounting assembly comprises a sliding mounting plate and a second sliding assembly, wherein the sliding mounting plate is mounted on the first sliding assembly, and the first sliding assembly can drive the sliding mounting assembly to move; the second sliding assembly is mounted on the sliding mounting plate; The detector mounting plate is mounted on the second sliding assembly, and the second sliding assembly can drive the detector mounting plate to move perpendicularly to the sliding direction of the first sliding assembly.

2. A CBCT flip stand according to claim 1, characterized in that: The fixing module comprises a third sliding assembly, and the third sliding assembly is mounted on the fixing plate; The column is installed on the third sliding assembly, and the third sliding assembly can drive the column to move.

3. A CBCT flip stand as claimed in claim 2, characterized in that: The first sliding assembly includes a first guide rail, a first slider, and a first driving assembly. The first guide rail is mounted on a rotating mounting plate, the first slider is mounted on the first guide rail, the sliding mounting plate is mounted on the first slider, the first driving assembly is mounted between the rotating mounting plate and the sliding mounting plate, and the first driving assembly drives the sliding mounting plate to move along the direction of the first guide rail; The second sliding assembly includes a second guide rail, a second slider, and a second driving assembly. The second guide rail is mounted on the sliding mounting plate. The second slider is mounted on the second guide rail. The detector mounting plate is mounted on the second slider. The second driving assembly is mounted between the sliding mounting plate and the detector mounting plate. The second driving assembly drives the detector mounting plate to move along the direction of the second guide rail. The third sliding assembly includes a third guide rail, a third slider, a movable plate, and a third driving assembly. The third guide rail is installed on a fixed plate, the third slider is installed on the third guide rail, the movable plate is installed on the third slider, the column is installed on the movable plate, and the third driving assembly is installed between the fixed plate and the movable plate. The third driving assembly drives the movable plate to move along the direction of the third guide rail.

4. A CBCT flip stand as claimed in claim 3, characterized in that: The number of the first guide rail, the second guide rail and the third guide rail is two.

5. The CBCT flip stand according to claim 3, characterized in that: The first sliding assembly includes a first limiting device, which is installed on the first guide rail to limit the sliding range of the first sliding block; The second sliding assembly includes a second limiting device, which is installed on the second guide rail to limit the sliding range of the second sliding block; The third sliding assembly includes a third limiting device, which is installed on the third guide rail to limit the sliding range of the third sliding block.

6. The CBCT flip stand according to claim 3, characterized in that: The first driving assembly includes a driving motor, a transmission assembly, a screw support seat, a ball screw, and a nut seat; The ball screw is mounted on the screw support seat, the nut seat is mounted on the ball screw, and the transmission assembly is connected to the drive motor and the ball screw; The second drive assembly and the third drive assembly have the same structure as the first drive assembly.

7. A CBCT flip stand according to any one of claims 1 to 6, characterized in that: It includes a rotation limiting device, which is installed between the column and the rotation mounting plate; The rotation limiting device limits the rotation angle of the rotating mounting plate to 90°.

8. The CBCT flip stand according to claim 7, characterized in that: The rotation limiting device comprises a rotation limiting block, a rotation shaft, and a limiting block mounting seat; The rotating shaft is arranged between the column and the rotating mounting plate, the rotating limit block is sleeved on the rotating shaft, and the rotating limit block and the rotating shaft are fixedly connected; The outer surface of the rotation limit block is composed of two continuous surfaces, one of which is a limit surface, and the limit surface includes a 90° arc surface and a plane extending in the tangent direction of the 90° arc surface; The limit block mounting seat is arranged on the rotating mounting plate, the rotating shaft passes through the limit block mounting seat, and the limit surface of the rotating limit block abuts against the plane of the rotating mounting plate.

9. The CBCT flip stand according to claim 7, characterized in that: The rotation limiting device comprises a rotation shaft, an angle indicating rod, a limiting rod mounting plate, a first angle limiting rod, and a second angle limiting rod; The rotating shaft is arranged between the column and the rotating mounting plate, and the angle indicating rod is installed at the end of the rotating shaft. When the rotating shaft rotates, the angle indicating rod rotates together; The first angle limiting rod and the second angle limiting rod are installed on the limiting rod installation plate, and the first angle limiting rod, the second angle limiting rod and the axis of the second rotating shaft form an angle of 90°; When the angle indicating rod contacts the first angle limiting rod and the second angle limiting rod, the rotation angle is limited.

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