CN201075302Y - Rotating device of display screen - Google Patents

Abstract

The utility model discloses a rotating device of a display screen, which mainly comprises a fixed shaft, a first linkage piece, a second linkage piece, an elastic piece and a driving piece, wherein the fixed shaft is used for connecting a bracket and a rotating head; the first linkage part is linked with the rotating head; the second linkage piece is linked with the bracket; the elastic piece is positioned between the first linkage piece and the second linkage piece; the driving piece is used for driving the second linkage piece to move towards the first linkage piece, so that when the second linkage piece is meshed with the first linkage piece, the elastic piece is compressed, and the rotating head cannot be rotated; when the driving piece is withdrawn, the second linkage piece moves towards the direction far away from the first linkage piece by virtue of the elasticity of the elastic piece, so that the first linkage piece and the second linkage piece are disengaged, and the rotating head can be rotated at the moment.

Description

Display Rotation Device

【Technical field】

The utility model relates to a rotating device for a display screen, in particular to a rotating device suitable for a touch-type liquid crystal display screen.

【Background technique】

With the continuous improvement of liquid crystal display technology, liquid crystal displays have been widely used. At present, liquid crystal displays in many commercial fields require touch-sensitive liquid crystal displays, so that end users can choose different operation instructions according to their own needs. Usually, the touch display screen has a rotating device connected to the display screen and its support, and the rotating device is used to provide its rotating function, such as turning up and down, so that the user can adjust the display screen to suit his own viewing habits. The angle of inclination can be kept stable after adjustment.

Please refer to Fig. 1A and Fig. 1B, the rotating device of the existing touch screen is mainly composed of the adjusting screw 90 and the friction pad 91. After the adjusting screw 90 is tightened, the friction pad 91 and the fixed A certain frictional force will be generated between the rotating heads 92 , and the rotating heads 92 are fixed in this way. But because the adjusting screw 90 is pre-adjusted according to the set value, after the rotating head 92 is installed, the torque is fixed and cannot be changed. Therefore, the rotating device of the existing touch screen can only provide constant torque.

In the above existing structure, in order to enable the touch screen to rotate smoothly under normal conditions, the predetermined torque used to drive the rotating device to work should not be too high, so as to facilitate adjustment. However, when the user is using the touch function, a force needs to act on the display screen, and different users have different forces, and the torque generated by the same user on the rotating device is also different when touching different areas. , when the torque exceeds the predetermined torque of the rotating device, the display screen will rotate. It can be seen that the existing display screen will be rotated at any time due to excessive operating force, thereby causing inconvenience to the user's operation.

Therefore, it is necessary to provide a new rotating device for a touch-screen display to overcome the defects in the existing rotating device.

【Content of invention】

The main purpose of the present invention is to provide a rotating device for a display screen, the rotating device can be locked at any desired position, so as to facilitate the user's operation.

Other purposes and advantages of the utility model can be further understood from the technical characteristics disclosed in the utility model.

In order to achieve the above purpose or other purposes, the utility model adopts the following technical solutions: a rotating device, which includes a bracket, a rotating head and a shaft assembly, wherein the bracket has at least one support arm; the rotating head is pivotally connected to On the bracket, the rotating head has a frame for fixing the display screen, and at least one rotating arm located on the frame; the shaft assembly is used for connecting the rotating head and the bracket, which includes a fixed shaft, a first linkage, The second linkage, an elastic piece and a drive, wherein the fixed shaft is used to pivotally connect the rotating arm of the rotating head to the support arm of the bracket; the first connecting member is installed on the fixed shaft and connected with the rotating head The first link has a first engaging part; the second link is installed on the fixed shaft and is connected with the bracket, and the second link has a second engaging part; the elastic part is installed on the fixed shaft and is located at the first Between the first linkage and the second linkage; the driving element is installed on the fixed shaft to drive the second linkage to move in the direction approaching or away from the rotating head. When the driving element moves in the direction approaching the rotating head , the elastic part is compressed, the second engaging part of the second linkage is engaged with the first engagement part of the first linkage, and when the two are fully engaged, the rotating head cannot be rotated; When the direction of the rotating head moves, the second link moves away from the link by the elastic force of the elastic member, so that the first engaging part of the first link is engaged with the second link of the second link. The parts are disengaged from the meshing relationship, and the rotating head can be rotated at this time.

Compared with the prior art, the rotation device of the utility model enables the rotation head to be locked through the meshing relationship between a first linkage connected with the rotation head and a second linkage connected with the bracket. or be loosened. When the user needs to adjust the angle of the display screen, the user only needs to withdraw the driving part outwards for a certain distance, and the second linking part will withdraw outwards under the elastic force of the elastic part, so that the gap between the first and second linking parts When the engaging parts of the second linkage are disengaged from the engagement relationship, the second linkage can no longer restrict the first linkage. At this time, the user can rotate the swivel head as required to adjust the angle of the display screen. After the angle is selected, the user can use the driving part to push the second linkage to the first linkage, so that the meshing relationship between the first and second linkages is established again, and the second linkage can now The first link is constrained so that the swivel head can be locked in the desired position. In this way, the user can use the display screen with peace of mind, without worrying that the display screen will rotate due to excessive operating force.

【Description of drawings】

1A and 1B are structural schematic diagrams of a conventional rotating device for a touch screen.

Fig. 2 is a disassembled schematic view of each component of the rotating device of the display screen of the present invention.

Fig. 3 is a schematic diagram of the overall structure of the rotating device of the display screen of the present invention.

4A and 4B are structural schematic diagrams of the first linkage of the present invention in different directions.

Fig. 5 is a schematic structural diagram of the second linkage of the present invention.

Fig. 6 is a schematic diagram of the rotating device of the display screen of the present invention in a locked state.

Fig. 7 is a schematic diagram of the rotating device of the display screen of the present invention in a loosened state.

【Detailed ways】

Please refer to FIG. 2 to FIG. 7 , the rotating device of a display screen in a preferred embodiment of the present invention mainly includes a bracket 10 , a rotating head 20 and a shaft assembly connecting the rotating head 20 and the bracket 10 . Support 10 has two support arms 11,12, and two support arms 11,12 are fixed, in order to support all other components of the rotating device, on which a support arm 11 is provided with a shaft hole 13 (please refer to Fig. 6 shown) and a second fixing portion, in this embodiment, the second fixing portion on the support arm 11 is a through hole 14 . The swivel head 20 is pivotally connected to the bracket 10. The swivel head 20 has a frame 21 for fixing the display screen, and two swivel arms 22, 23 respectively located on both sides of the frame 21, wherein a swivel arm 22 is formed with a The shaft hole 24 and a first fixing portion, in this embodiment, the first fixing portion on the rotating arm 22 is a notch 25 .

As shown in FIG. 2 , each support arm 11 , 12 of the bracket 10 also has two protruding stoppers 15 , 16 , and a slideway 17 is formed between the two stoppers 15 , 16 , and each rotating arm 22, 23 of the rotating head 20 is provided with a slider 26, when the position of the rotating head 20 is adjusted, the sliding block 26 on the rotating head 20 can be positioned at the two stoppers 15, 23 of the bracket 10. 16 to slide in the slideway 17, and the sliding range is limited by the two limiting parts 15, 16, so as to prevent the turning head 20 from over-rotating to an unnecessary position.

The above shaft assembly is installed on one of the support arms 11 of the bracket 10 , and the shaft assembly mainly includes a fixed shaft 30 , a first link 40 , a second link 50 , an elastic member 60 and a driving member 70 . Wherein the fixed shaft 30 passes through the shaft hole 13 on one of the supporting arms 11 of the bracket 10 and the shaft hole 24 on one of the rotating arms 22 of the rotating head 20, so as to pivotally connect the rotating arm 22 of the rotating head 20 to the on the support arm 11 of the bracket 10. The first linking member 40 , the second linking member 50 , the elastic member 60 and the driving member 70 are sequentially installed on the fixed shaft 30 and are separated from the rotating head 20 in turn. The first link 40 is connected with the rotary head 20 . The second link 50 is connected with the bracket 10 . The elastic member 60 is located between the first linking member 40 and the second linking member 50 . The driving member 70 is movable on the fixed shaft 30 in a direction approaching and away from the rotating head 20 .

Please continue to refer to Figure 2, in this embodiment, the shaft assembly also includes a bolt 81 and several friction washers 82, 82', wherein the bolt 81 can be screwed to one end of the fixed shaft 30, so that the fixed shaft can be 30 lock; while the friction pads 82, 82' are used to improve the tightness between the components, the friction pads 82, 82' are installed on the fixed shaft 30, and are respectively located on both sides of the bracket 10 and the rotating head 20 .

Please refer to FIG. 4A and FIG. 4B , in this embodiment, the first link 40 is a one-piece structure, which has a cylindrical shape that can be attached to the side plane of the rotating arm 22 of the rotating head 20. The main body 44 and a gear 45 disposed on one side of the main body 44 and coaxial with the main body 44 . The center of the main body 44 is provided with a shaft hole 41 for the fixed shaft 30 to pass through, and the outer edge of the main body 44 opposite to the gear 45 is provided with a protrusion 42, and the periphery of the gear 45 is formed with a number of respectively straight meshing tooth 43. The meshing tooth 43 is called the first meshing part, and the projection 42 is called the first linking part of the first linking part 40, which can cooperate with the first fixed part of the rotary head 20, that is, it can be snapped on In the notch 25 on the rotating arm 22, the first linkage 40 can form a linkage with the rotation head 20, that is, when the rotation head 20 rotates, the first linkage 40 will also rotate accordingly. In addition, the shaft hole 41 of the first linkage 40 passes through the center of the main body 44 and the gear 45, and forms a circular accommodation cavity 441 at the center of the main body 44 for accommodating several friction pads 82'; A circular receiving cavity 451 is also formed at the center of the gear 45 for receiving the elastic member 60 .

Please refer to FIG. 5 , in this embodiment, the second linkage 50 is an integral structure, which has a cylindrical main body 54, and the center of the main body 54 has a shaft hole 51 through which the fixed shaft 30 passes. There is a positioning rod 52 with a certain length on the outer edge of the main body 54 . A circular engagement cavity 541 is also formed at the central position of the side surface of the main body 54, and a plurality of engagement teeth 53 are formed on its inner surface. The shapes are the same, so the meshing cavity 541 is used to accommodate the gear 45 of the first linkage 40 . The positioning rod 52 is called the second linkage part of the second linkage 50, and it can cooperate with the positioning part of the bracket 10, that is, it can extend into the through hole 14 on the support arm 11 of the bracket 10, so that The second linkage 50 can form linkage with the bracket 10 . In detail, if the bracket 10 is fixed, the second linkage 50 will not rotate, that is, the bracket 10 can limit the degree of freedom of the second linkage 50 in the direction of rotation, and when the second linkage When the member 50 slides horizontally along the fixed shaft 30, because the positioning rod 52 has a certain length, the positioning rod 52 will not escape from the through hole 14 of the bracket 10, thereby ensuring that the second linkage 50 can always be formed with the bracket 10. Gearing.

Referring to the sectional view shown in FIG. 6 , it can be seen that the section of the gear 45 of the first link 40 is designed to be tapered, and the meshing cavity 541 of the second link 50 also has a tapered section. When the driving member 30 moves in a direction close to the rotating head 20, the elastic member 60 is compressed, and the engagement cavity 541 of the second linking member 50 gradually accommodates the gear 45 of the first linking member 40, and the second linking member 50 The second meshing portion (that is, the meshing tooth 53) is meshed with the first meshing portion (that is, the meshing tooth 43) of the first linkage 40, and when the two are fully meshed, the first linkage 40 can no longer be engaged. Rotate, so that the swivel head 20 can no longer be swiveled, in this way the swivel head 20 is fixed. And when the driving member 70 moves away from the rotating head 20, the second link 50 moves away from the first link 40 by the elastic force of the elastic member 60. When the first link 40 moves When the gear 45 withdraws from the meshing cavity 541 of the second linkage 50 for a certain distance, the first meshing portion (that is, the meshing tooth 43 ) of the first linkage 40 is engaged with the second meshing portion (that is, the meshing tooth 43 ) of the second linkage 50 . Teeth 53) are out of mesh, at this time, the second linkage 50 can no longer restrict the first linkage 40, and of course it can no longer restrain the rotating head 20, so that the rotating head 20 can be arbitrarily within its allowable range. turn.

Since the gear 45 of the first linkage 40 and the meshing cavity 541 of the second linkage 50 are tapered, as long as the gear 45 of the first linkage 40 withdraws from the meshing cavity 541 of the second linkage 50 for a short distance distance, the meshing teeth 43 and 53 of the first link 40 and the second link 50 will loosen each other, that is, the gear 45 of the first link 40 does not completely exit the meshing cavity of the second link 50 541 to release the meshing relationship between the two, so the meshing structure with a tapered section can achieve the purpose of convenient operation.

Please refer to FIG. 2 , FIG. 6 and FIG. 7 . In this embodiment, the elastic member 60 is a spring, and the driving member 70 is in the shape of a handle. The driving part 70 includes an operating part 71 located at one end of the driving part 70 and operable by a user, and a mounting part 72 located at the other end of the driving part 70 and capable of being mounted on the fixed shaft 30 . The mounting portion 72 has a cylindrical hollow cavity 73 , and a threaded portion 74 of a certain length is formed at the end of the hollow cavity 73 . The side wall of the hollow cavity 73 is then processed with a through limiting hole 75, and a screw 76 is assembled therein, and when the screw 76 is screwed into the limiting hole 75, a part of the end of the screw 76 will extend into the hollow cavity 73. Inside.

In this embodiment, the fixed shaft 30 of the shaft assembly has two threaded sections 31, 34 respectively located at the ends of the fixed shaft 30, and a polished rod section 32 and a limiting section 33 located between the two threaded sections 31, 34 . The threaded section 31 located at the end of the fixed shaft 30 close to the bracket 10 is used for cooperating with the bolt 81 to fix the fixed shaft 30 on the bracket 10 . The polished rod section 32 is used to carry the rotating head 20, the first link 40, the elastic member 60, the second link 50, and several friction pads 82'. Two convex rings 35, 36 are arranged on the left and right sides of the limiting section 33, which can extend into the hollow cavity 73 of the driver 70, and the end of the screw 76 extending into the hollow cavity 73 is between the two convex rings 35, 36. During this period, when the driving member 70 moves forward or backward, the moving distance of the driving member 70 can be limited by the two protruding rings 35, 36 and the screw 76 extending into the hollow cavity 73, as shown in Figure 6 and Figure 7 . The threaded segment 34 at the other end of the fixed shaft 30 is used to cooperate with the threaded portion 74 in the hollow cavity 73 of the driving member 70 , and in this way the driving member 70 is positioned on the fixed shaft 30 .

Please refer to FIG. 6 again, the assembly relationship of each component of the rotating device of the display screen of the present invention and the adjustment method of the rotating head 20 will be described in detail again below.

First, the fixed shaft 30 is inserted into the shaft hole 13 of the rotating head 20 and the bracket 10, then a plurality of friction pads 82 are installed on the fixed shaft 30 on one side of the bracket 10, and then a bolt 81 is installed on the On the threaded segment 31 at one end of the fixed shaft 30 , the fixed shaft 30 is fixed on the bracket 10 like this.

Next, the other friction pads 82', the first link 40, the elastic member 60, the second link 50 and the driving member 70 are installed on the fixed shaft 30 in sequence. Wherein the friction pad 82' is accommodated in the accommodation cavity 441 of the first linkage 40 facing the bracket 10 side. The main body 44 of the first linkage 40 is attached to the side plane of the turning arm 22 of the turning head 20, and the protrusion 42 of the first linkage 40 (that is, the first linkage part of the first linkage 40) It is buckled in the notch 25 (also known as the first fixed part) of the rotating head 20, and the positioning rod 52 of the second linkage 50 (that is, the second linkage part of the second linkage 50) is extended into the bracket 10 through hole 14 (also known as the second fixed part), and the gear 45 of the first linkage 40 is completely extended into the engagement cavity 541 of the second linkage 50, at this time the engagement of the first linkage 40 The tooth 43 (also known as the first meshing portion) is in complete mesh with the meshing tooth 53 (also known as the second meshing portion) of the second linkage 50 . The elastic member 60 is located between the first and second linkages 50 and is squeezed by the two linkages. At this time, the elastic member 60 is stored in the first linkage 40 in a compressed state and faces the second linkage. 50 in the accommodation chamber 451. The driving member 70 is installed at the end of the fixed shaft 30 and abuts against the outer surface of the second linkage 50, which is convenient for the user to provide external force to the second linkage 50, wherein the limiting section 33 of the fixed shaft 30 and the fixed The threaded section 34 at the end of the shaft 30 extends into the hollow cavity 73 of the driver 70, and the threaded section 34 matches the threaded part 74 located in the hollow cavity 73 of the driver 70, so that the driver can be installed on the fixed shaft 30 superior.

Finally, a screw 76 is screwed into the limit hole 75 on the side wall of the hollow cavity 73, and the end of the screw 76 is stretched into the hollow cavity 73, and the end of the screw 76 stretched into the hollow cavity 73 is just right Located between the two protruding rings 35 , 36 of the fixed shaft 30 , this can limit the moving distance of the driving member 70 in the horizontal direction.

Please refer to FIG. 7 , when the user needs to adjust the angle of the display screen, he only needs to turn the handle-shaped driving part 70 counterclockwise, so that the driving part 70 withdraws outwards, and the second linking part 50 will also be on the elastic part 60. Under the action of the elastic force, the first and second linkages 40, 50 both adopt the meshing teeth 43, 53 with tapered cross-sections, so as long as the second linkage 50 withdraws outward for a short distance, the It is sufficient to disengage the second meshing portion (that is, the meshing tooth 53 ) of the second linkage 50 from the first meshing portion (that is, the meshing tooth 43 ) of the first linkage 40 . When the meshing relationship between the first link 40 and the second link 50 disappears, the second link 50 can no longer restrict the first link 40, and the user can rotate the rotating head 20 as needed. .

After the display screen is rotated to the position desired by the user, the user can rotate the driving member 70 clockwise, so that the driving member 70 moves toward the second linkage 50 and pushes the second linkage 50 to move toward the first linkage 40 , when the gear 45 of the first linkage 40 is completely accommodated in the engagement cavity 541 of the second linkage 50, the first meshing portion (that is, the meshing teeth 43) of the first linkage 40 and the second linkage The second engaging portion (that is, the engaging tooth 53 ) of the member 50 is fully engaged, and at this moment, the first linkage member 40 can no longer be rotated, so that the rotating head 20 can be fixed again. At this time, the user can use the display screen with confidence, without worrying about the situation that the display screen will rotate due to excessive operating force.

Please refer to Fig. 2 again, in this embodiment, the shaft assembly of the present utility model is installed on one of the support arms 11 of the bracket 10, and on the other support arm 12 of the bracket 10, an adjusting screw 90 is installed. And the existing rotating device that friction pad 91 forms. Therefore, in this embodiment, the positioning of the display screen in a fixed state mainly depends on the shaft assembly of the utility model, while the positioning of the display screen in a rotating state mainly relies on the existing rotating device. In detail, when the rotating head 20 is in the state of being allowed to be rotated, generally speaking, due to the action of gravity, the rotating head 20 will rotate downward rapidly, but because the adjusting screw 90 and the friction pad 91 on the other side of the bracket 10 can A certain friction force is provided, so that the rotating head 20 can be prevented from rotating downwards, thereby protecting the display screen from being shaken excessively. When the user adjusts the rotating head 20, he only needs to use a little force to overcome the friction existing on the other side and find an appropriate use angle.

Claims (23)

1. the wheelwork of a display screen, it includes: a support and a rotary head, its medium-height trestle has at least one sway brace; Rotary head is articulated on the support, and rotary head has one in order to fixedly framework and at least one swivel arm that is positioned on the framework of display screen; It is characterized in that: this wheelwork also includes an axial region assembly, in order to connect rotary head and support, this axial region assembly includes: a stationary shaft, first moving part, second moving part, an elastic component and an actuator, and wherein stationary shaft is articulated on the sway brace of support in order to the swivel arm with rotary head; First moving part be installed on the stationary shaft and with rotary head interlock mutually, this first moving part has one first engaging piece; Second moving part be installed on the stationary shaft and with support interlock mutually, second moving part has one second engaging piece, in order to be meshed with first engaging piece of first moving part; Elastic component is installed on the stationary shaft and between first moving part and second moving part; And actuator is installed on the stationary shaft, in order to drive second moving part along near or move away from the direction of rotary head, when actuator moves along the direction near rotary head, elastic component is compressed, second engaging piece of second moving part is meshed with first engaging piece of first moving part, and rotary head can not be rotated; And when actuator when the direction away from rotary head moves, second moving part is by the elastic force of elastic component and move towards the direction away from first moving part, make between second engaging piece of first engaging piece of the moving part of winning and second moving part to break away from meshing relation, this moment, rotary head can be rotated.

2. the wheelwork of display screen as claimed in claim 1, it is characterized in that: the sway brace of described support has one second fixed part, and described second moving part has second linkage part that matches with second fixed part of sway brace.

3. the wheelwork of display screen as claimed in claim 2, it is characterized in that: the swivel arm of described rotary head has one first fixed part, and first moving part has first linkage part that matches with first fixed part of swivel arm.

4. the wheelwork of display screen as claimed in claim 3, it is characterized in that: the sway brace of described support and the swivel arm of described rotary head all provide an axis hole, use for stationary shaft and pass.

5. the wheelwork of display screen as claimed in claim 3 is characterized in that: all provide an axis hole on described first and second moving part, use for stationary shaft and pass.

6. the wheelwork of display screen as claimed in claim 3, it is characterized in that: described first moving part has a main body and that is posted by on the swivel arm of rotary head and is arranged at main body one side and the gear coaxial with main body, first linkage part of described first moving part is arranged on the main body, and first engaging piece of first moving part then is arranged on the gear.

7. the wheelwork of display screen as claimed in claim 6, it is characterized in that: the gear of described first moving part is taper.

8. the wheelwork of display screen as claimed in claim 7 is characterized in that: first linkage part of described first moving part is one to be formed at the projection on this main body, and first engaging piece of described first moving part is several engaging tooths that are formed at the gear periphery.

9. the wheelwork of display screen as claimed in claim 8, it is characterized in that: first fixed part of the swivel arm of described rotary head is a breach.

10. the wheelwork of display screen as claimed in claim 9, it is characterized in that: respectively be formed with a circular host cavity in the main body of described first moving part and the center of gear, elastic component is contained in the circular host cavity of gear.

11. the wheelwork of display screen as claimed in claim 10, it is characterized in that: described second moving part has a main body, be formed with an engagement chamber in the wherein center of a side surface of main body, in order to accommodate the gear of first moving part, second linkage part of described second moving part is arranged on the main body, and second engaging piece of described second moving part is arranged in the engagement chamber.

12. the wheelwork of display screen as claimed in claim 11 is characterized in that: this engagement chamber that second moving part is set is taper.

13. the wheelwork of display screen as claimed in claim 12, it is characterized in that: this second linkage part of described second moving part is one to be formed at the backstay with certain-length on this main body, and second engaging piece of described second moving part is several engaging tooths that are formed on the inside surface in engagement chamber.

14. the wheelwork of display screen as claimed in claim 13 is characterized in that: second fixed part of the sway brace of described support is a through hole.

15. the wheelwork of display screen as claimed in claim 14 is characterized in that: described actuator is handle shape, and it includes an operating portion and an installation portion.

16. the wheelwork of display screen as claimed in claim 15 is characterized in that: the installation portion of described actuator has a hollow cavity, and the end of hollow cavity is formed with a threaded portion.

17. the wheelwork of display screen as claimed in claim 16, it is characterized in that: described wheelwork also comprises a screw, form a spacing hole on the sidewall of the hollow cavity of actuator, screw is assembled in the spacing hole of actuator, and the end of screw stretches in the hollow cavity.

18. the wheelwork of display screen as claimed in claim 17 is characterized in that: described stationary shaft has two thread segments that lay respectively at two ends of stationary shaft, and the polished rod section between two thread segments and one spacing section.

19. the wheelwork of display screen as claimed in claim 18, it is characterized in that: spacing section two ends, the left and right sides of described stationary shaft have two bulge loops, and two bulge loops stretch in this hollow cavity of this actuator, and the screw end in hollow cavity then is between two bulge loops.

20. the wheelwork of display screen as claimed in claim 19, it is characterized in that: described axial region assembly also includes a bolt and several friction shims, wherein the thread segment of close support one end of bolt territory stationary shaft matches, and these friction shims then are contained in the host cavity of main body of first moving part.

21. the wheelwork of display screen as claimed in claim 20 is characterized in that: described at least one sway brace is two sway braces, and described at least one swivel arm is two swivel arms.

22. the wheelwork of display screen as claimed in claim 21 is characterized in that: described axial region assembly is installed on the wherein sway brace of support.

23. the wheelwork of display screen as claimed in claim 22, it is characterized in that: all have two limiting sections that are convex on each sway brace of described support, then all have a slide block on each swivel arm of described rotary head, and the slide block of swivel arm is between two limiting sections of this sway brace.

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