CN213909356U

CN213909356U - Sofa backrest preventing clamping and exposing

Info

Publication number: CN213909356U
Application number: CN202022143149.9U
Authority: CN
Inventors: 李云海; 姚有贵; 崔振
Original assignee: Kuka Home Co Ltd
Current assignee: Kuka Home Co Ltd
Priority date: 2020-09-25
Filing date: 2020-09-25
Publication date: 2021-08-10
Anticipated expiration: 2030-09-25

Abstract

The application relates to a sofa backrest which is prevented from being clamped and not exposed, comprising a back frame wood frame; the headrest plate is rotatably connected to the upper end of the back frame wood frame through the connecting component; the driving piece is used for driving the headrest plate to rotate relative to the back frame wood frame; the lower back is fixedly arranged on one side of the back frame wood frame; the cladding cover is sleeved with the cladding back frame wood frame, the headrest plate and the lower back, and a filling layer is arranged in the cladding cover. The driving piece drives the head leaning plate to rotate relative to the back frame wooden frame. Under the effect of cladding cover and filling layer, when leaning on the relative back of the body frame wooden frame of head plate rotated, the position that leans on the head plate to correspond can rotate with relative back of the body frame to the rotation of leaning on the head has been realized. Because the back frame wooden frame, the headrest plate, the connecting assembly and the driving piece are all wrapped under the wrapping sleeve and filled with the filling layer, no metal piece is exposed, and only rust prevention treatment and appearance treatment are needed. Meanwhile, the risk of clamping hands is avoided, and potential safety hazards are reduced.

Description

Sofa backrest preventing clamping and exposing

Technical Field

The application relates to the field of furniture, in particular to a sofa backrest capable of preventing clamping and not exposing.

Background

Sofas are common household articles, the headrests of common sofas are fixed, the positions and the states of the headrests cannot be adjusted according to the postures of people, and some electric sofas are available in the market at present, have the function of adjusting the headrests, and improve the comfort level of users.

The patent with application number CN201920216201.3 discloses a turnover headrest device for sofa, which is characterized by comprising a sofa frame and a turnover mechanism, wherein the sofa frame comprises a sofa frame top and two sofa frame side parts which are connected in a matching manner, the turnover mechanism comprises a driver rotatably connected in the sofa frame, a turnover rod rotatably connected with the driver, a plane link mechanism and a backrest part, the plane link mechanism comprises a crank rod, a first connecting rod and a second connecting rod, one end of the crank rod is fixedly connected with the turnover rod, the middle part of the crank rod is rotatably connected with the first connecting rod, the other end of the crank rod is rotatably connected with the second connecting rod, and the first connecting rod and the second connecting rod both penetrate through the sofa frame top and are rotatably connected with the backrest part.

The during operation, the third connecting rod, the crank rod, rocker and first connecting rod extension constitute a plane four-bar linkage, the crank rod, first connecting rod, the second connecting rod also constitutes a plane four-bar linkage with leaning on the head fixed part, the driver promotes the upset of upset pole, the upset pole drives first plane link linkage folding slope up, and then make the folding slope of second plane four-bar linkage, wherein, when the crank rod rotates, lean on the head fixed part and lean on the head to rotate thereupon, lean on the head to realize following action: from an upper end lying parallel to the top of the sofa frame to an upper end "standing" from the top of the sofa frame. When the driver is reset, the driver stops working and automatically resets by using the pulling force of the reset spring.

Because first connecting rod and second connecting rod wear out outside the sofa frame, and have the gap between the two, so, above-mentioned headrest subassembly produces the scissors contained angle at rising exhibition and withdrawal in-process, presss from both sides wounded people's hand easily, has great potential safety hazard.

In view of the above-mentioned related art, the inventor believes that the existing headrest mechanism has the defect that the user is injured by the hand.

Disclosure of Invention

In order to reduce the potential safety hazard, the application provides an prevent pressing from both sides unexposed sofa back, adopts following technical scheme:

the utility model provides a prevent pressing from both sides unexposed sofa back which characterized in that: comprises that

A back frame wooden frame;

the headrest plate is rotatably connected to the upper end of the back frame wood frame through the connecting component;

the driving piece is arranged in the back frame wooden frame and is used for providing a linear pair to drive the headrest plate to rotate relative to the back frame wooden frame;

the lower back is fixedly arranged on one side of the back frame wooden frame, and the head rest plate and the lower back are positioned on the same side of the back frame wooden frame;

the wrapping sleeve is provided with a wrapping back frame wood frame, a headrest plate and a lower back, and a filling layer used for increasing the softness of the headrest is arranged in the wrapping sleeve.

Through adopting above-mentioned technical scheme, rotate by the relative back of the body frame timber frame of driving piece drive headrest plate spare. Under the effect of cladding cover and filling layer, when leaning on the relative back of the body frame wooden frame of head plate rotated, the position that leans on the head plate to correspond can rotate with relative back of the body frame to the rotation of leaning on the head has been realized. Because the back frame wooden frame, the headrest plate, the connecting assembly and the driving piece are all wrapped under the wrapping sleeve and filled with the filling layer, no metal piece is exposed, and only rust prevention treatment and appearance treatment are needed. Meanwhile, the risk of clamping hands is avoided, and potential safety hazards are reduced.

Optionally, the connecting assembly comprises

A back frame connecting rod;

the headrest plate connecting rod is fixedly connected to the headrest plate and is rotatably connected to the back frame connecting rod;

the two ends of the transmission component are respectively connected with the back frame connecting rod and the headrest plate connecting rod and are used for converting the force of the driving piece into a rotating pair which is connected with the headrest plate connecting rod and rotates relative to the back frame connecting rod;

the back frame wooden frame comprises

The top plate is provided with a through groove for the upper end of the transmission assembly to penetrate through;

the side plates are fixedly connected to the two sides of the top plate, and the connecting assembly is positioned between the two side plates;

and the fixing rod is positioned between the two side plates and is used for fixedly connecting the two side plates.

Through adopting above-mentioned technical scheme, adopt embedded scheme, reduce the constriction to coupling assembling, imbed the inside of back of the body frame wooden frame, make coupling assembling not expose. There is no risk of pinching during headrest rotation.

Optionally, the headrest plate is located right above the two side plates in the closed state.

Through adopting above-mentioned technical scheme, back of the body frame wooden frame can play the effect of a support to leaning on the head plate to make the sofa have more the wholeness.

Optionally, the transmission assembly includes a first transmission rod and a second transmission rod, one end of the first transmission rod is rotatably connected to the headrest plate connecting rod, the output end of the driving member is rotatably connected to the first transmission rod, one end of the second transmission rod is rotatably connected to the first transmission rod and the other end of the second transmission rod is rotatably connected to the back frame connecting rod, and one end of the driving member, which is far away from the first transmission rod, is rotatably connected to the back frame connecting rod; a guide groove is formed in the first force transmission rod, and a guide shaft which is slidably embedded in the guide groove is arranged on the back frame connecting rod.

Through adopting above-mentioned technical scheme, when the driving piece gave first power transmission pole straight line vice, first power transmission pole rotated back of the body frame connecting rod relatively under the direction of guide way, and the tie point position between first power transmission pole and the head board connecting rod that leans on at this moment changes to the relative back of the body frame connecting rod of drive head board connecting rod rotates. The rotation of the headrest relative to the back frame is realized. Meanwhile, the structure of the scissors and the fork cannot be generated, and the safety is higher.

Optionally, establish the tie point of first dowel bar and second dowel bar is A, establishes the tie point of second dowel bar and back of the body frame connecting rod is B, establishes the tie point of the output of first dowel bar and driving piece is C, and ABC three points form triangle-shaped.

Through adopting above-mentioned technical scheme, the triangle-shaped of ABC three point formation through its triangle-shaped stability, guarantees that first force transmission pole does not reciprocate, makes its biography power more stable.

Optionally, establish the tie point of first dowel steel and back of the body board connecting rod is D, establishes the tie point of back of the body board connecting rod and back of the body frame connecting rod is E, and CDE three points form triangle-shaped.

Through adopting above-mentioned technical scheme, the triangle-shaped control that CDE three points formed leans on the head board connecting rod can not rock backward.

Optionally, the ABDE four points form a quadrilateral.

By adopting the technical scheme, the ABDE four points form a quadrangle, and the stable operation of the head rest plate connecting rod is ensured.

Optionally, a cross-sectional center point of the guide shaft is set to be F, a connecting point of the driving piece and the back frame connecting rod is set to be G, and the three points CFG form a triangle.

By adopting the technical scheme, the stability of the point C is controlled by a triangle formed by three points CFG and the self-locking force of the driving piece. The connecting assembly can completely control the backrest plate connecting rod to not shake through limiting through the driving piece in a completely opened state, and the requirement of a user that the sofa backrest head does not shake in the using process is met.

Optionally, coupling assembling is equipped with two sets ofly and is located respectively by head plate both sides, the driving piece be equipped with one and with one of them of two sets of coupling assembling be connected.

Through adopting above-mentioned technical scheme, be different from the structure of motor in the centre of marketing, because the coupling assembling of this design can not rock, so the driving piece of this design can be installed on the coupling assembling of one side wherein, vacates in the middle of the back of the body frame wooden frame, does not have the object to block, and the user can be more comfortable by leaning on the sofa back. Meanwhile, the driving piece is arranged on the connecting component on one side, so that a transverse connecting rod is not needed, the transverse width of the back frame wooden frame can be adjusted at will according to requirements, and the whole width is adjusted more flexibly.

Optionally, an installation seat is arranged between the back frame connecting rod and the driving piece, the installation seat is detachably connected to the back frame connecting rod, and the driving piece is rotatably connected to the back frame connecting rod through the installation seat; the back frame connecting rod is fixedly installed on the back frame wooden frame through a screw rod, and the headrest plate connecting rod is fixedly installed on the headrest plate through a screw rod.

Through adopting above-mentioned technical scheme, whole coupling assembling and driving piece are integrated on changing the back of the body frame connecting rod that coupling assembling corresponds, when installing sofa with coupling assembling on, only need simple will lean on the head board connecting rod to install on leaning on the head board through the screw rod, will back of the body the frame connecting rod install back of the body frame wooden frame can, convenient operation has improved the installation effectiveness.

First aspect, the application provides an it does not expose to prevent pressing from both sides by head rotation regulation functional assembly, adopts following technical scheme:

a head rest rotation adjusting functional component capable of preventing clamping and not exposing comprises a transmission component and a driving component.

In summary, the present application includes at least one of the following beneficial technical effects:

1. no metal part is exposed, and the connecting component only needs to be subjected to rust prevention treatment and does not need to be subjected to appearance treatment;

2. the risk of clamping hands can not exist, and the potential safety hazard is reduced;

3. the four-bar mechanism, the three triangles and the self-locking force of the driving piece are mutually supported and limited, and the head rest plate connecting rod does not shake forwards and backwards when the connecting assembly is completely lifted and unfolded, so that the use comfort level is improved;

4. the driving piece is arranged on the connecting component at one side, so that the width of the headrest can be set more freely;

5. the connecting assembly is modularized, and the installation efficiency of sand production can be improved.

Drawings

FIG. 1 is a schematic structural view of the embodiment without the cover.

FIG. 2 is a schematic structural view of the embodiment without the cover.

FIG. 3 is a schematic structural view of the head rest of the embodiment in a closed state.

FIG. 4 is a schematic structural view of the head rest of the embodiment in an open state.

Fig. 5 is a partial schematic view of an embodiment.

FIG. 6 is a schematic structural view of a connecting assembly in an embodiment;

FIG. 7 is a schematic diagram of an embodiment embodying ABC.

FIG. 8 is a schematic diagram of an embodiment for embodying a CDE.

FIG. 9 is a schematic diagram of an embodiment for embodying ABDE.

Fig. 10 is a schematic diagram of an embodiment for embodying a CFG.

Fig. 11 is an enlarged view at a in fig. 5.

Description of reference numerals: 1. a back frame wooden frame; 2. a headrest plate; 3. a lower back; 4. a limiting plate; 5. a connecting assembly; 6. a drive member; 7. a backrest part; 8. a head rest; 9. a back portion; 10. a top plate; 11. a side plate; 12. fixing the rod; 13. a first transfer lever; 14. a second dowel bar; 15. a mounting seat; 16. a back frame connecting rod; 17. a headrest plate connecting rod; 18. a transmission assembly; 19. a guide groove; 20. a guide shaft; 21. a limiting groove; 22. and a limiting shaft.

Detailed Description

The present application is described in further detail below with reference to figures 1-11.

The embodiment of the application discloses prevent pressing from both sides unexposed sofa back. Referring to fig. 1 and 2, the sofa backrest includes a back frame wooden frame 1, a headrest plate 2, a headrest rotation adjustment function assembly, a lower back 3, and a cover. The headrest rotation adjustment functional assembly comprises a connecting assembly 5 and a driving member 6. The headrest plate 2 is rotatably connected to the back frame wooden frame 1 through a connecting assembly 5. Coupling assembling 5 is equipped with two sets ofly and is located respectively by head plate 2 both sides, and driving piece 6 is equipped with one and is connected with one of them of two sets of coupling assembling 5. The lower back 3 is fixedly arranged on one side of the back frame wooden frame 1, and the headrest plate 2 and the lower back 3 are positioned on the same side of the back frame wooden frame 1.

Referring to fig. 2 and 3, the wrapping sleeve is provided with a wrapping back frame wood frame 1, a headrest plate 2 and a lower back 3, and a filling layer for increasing the softness of the headrest is arranged in the wrapping sleeve. Referring to fig. 3 and 4, the back frame 1 after being coated forms a back portion 9, the lower back 3 after being coated forms a backrest portion 7, and the headrest plate 2 after being coated forms a headrest portion 8. The headrest 8 is pivotally connected to the rear back 9 and the backrest 7.

In use, the driving member 6 gives a driving force to the connecting assembly 5, and the connecting assembly 5 drives the headrest plate 2 to rotate relative to the back frame wooden frame 1 after force is transmitted, and the headrest 8 rotates relative to the back 9 and the backrest 7. Thereby adjusting the relative angle between the backrest part 7 and the headrest part 8 and allowing the user to adjust the headrest angle according to the own requirements. All metal parts are positioned in the coating sleeve, so that no metal part is exposed, and only rust prevention treatment and appearance treatment are needed. Meanwhile, the risk of clamping hands is avoided, and potential safety hazards are reduced.

Because the back frame wooden frame 1, the headrest plate 2, the connecting assembly 5 and the driving piece 6 are all wrapped under the wrapping sleeve and filled with the filling layer, no metal piece is exposed, and only rust-proof treatment and appearance treatment are needed. Meanwhile, the risk of clamping hands is avoided, and potential safety hazards are reduced.

Specifically, referring to fig. 2 and 5, the back frame 1 includes a top plate 10, side plates 11 fixedly connected to both sides of the top plate 10, and a fixing rod 12 located between the two side plates 11 and used for fixedly connecting the two side plates 11. The two side panels 11 are arched backwards to form the lower back 3. The connecting assembly 5 comprises a back frame connecting rod 16, a headrest plate connecting rod 17 and a transmission assembly 18. The transmission assembly 18 comprises a first transmission rod 13 and a second transmission rod 14.

Referring to fig. 5 and 6, an installation seat 15 is arranged between the back frame connecting rod 16 and the driving member 6, the installation seat 15 is detachably connected to the back frame connecting rod 16, and the driving member 6 is rotatably connected to the back frame connecting rod 16 through the installation seat 15; the back frame connecting rod 16 is fixedly arranged on the back frame wooden frame 1 through a screw, and the head board leaning connecting rod 17 is fixedly arranged on the head board leaning through a screw.

Referring to fig. 5 and 6, the back frame connecting rod 16 is fixedly connected to the inward side of the side plate 11. The headrest plate connecting rod 17 is fixedly connected to the headrest plate 2, and the headrest plate connecting rod 17 is rotatably connected to the upper end of the back frame connecting rod 16. The headrest plate connecting rod 17 is positioned on one side of the back frame connecting rod 16 departing from the corresponding side plate 11. The top plate 10 is provided with a through groove for the upper end of the head plate connecting rod 17 to pass through the top plate 10.

Referring to fig. 5 and 6, one end of the first transmission rod 13 is rotatably connected to the headrest plate connecting rod 17 and is located on the side of the headrest plate connecting rod 17 departing from the back frame connecting rod 16. A guide groove 19 is formed in the first force transmission rod 13, and the guide groove 19 is arc-shaped and is located at one end, far away from the headrest plate connecting rod 17, of the first force transmission rod 13. The back frame connecting rod 16 is fixedly provided with a guide shaft 20 which is slidably embedded in the guide groove 19. The second force transmission rod 14 has one end rotatably connected to the first force transmission rod 13 and the other end rotatably connected to the back frame connecting rod 16. The second force transmission rod 14 is positioned on the side of the first force transmission rod 13 which faces away from the back frame connecting rod 16. The output end of the driving member 6 is rotatably connected to a first transfer lever 13. The end of the driving piece 6 far away from the first force transmission rod 13 is rotatably connected with a mounting seat 15. The mounting seat 15 is fixedly connected to the side of the back frame connecting rod 16 far away from the side plate 11 through a bolt. The drive 6 is an electric cylinder. And the driving member 6 is mounted on the side of the first force transmission rod 13 facing away from the back frame connecting rod 16.

When the angle of the headrest plate 2 relative to the back frame 1 is adjusted, the driving member 6 gives a driving force to the first power transmission lever 13, so that the first power transmission lever 13 is rotated, and the guide shaft 20 slides in the guide groove 19. Due to the rotation of the first transmission rod 13, the headrest plate connecting rod 17 rotates relative to the back frame connecting rod 16, so that the headrest plate 2 is driven, and the headrest plate 2 is adjusted.

Referring to fig. 7, the integrated transmission assembly 18 does not shake in order to make the headrest plate 2 rotate more stably. The tie point of establishing first dowel steel 13 and second dowel steel 14 is A, the tie point of second dowel steel 14 and back of the body frame connecting rod 16 is B, the tie point of the output of first dowel steel 13 and driving piece 6 is C, the tie point of first dowel steel 13 and headrest plate connecting rod 17 is D, the tie point of headrest plate connecting rod 17 and back of the body frame connecting rod 16 is E, the cross-section centre of circle point of guiding axle 20 is F, the tie point of driving piece 6 and back of the body frame connecting rod 16 is G. Referring to FIG. 7, three points ABC form a triangle. Referring to fig. 8, three points of the CDE form a triangle. Referring to fig. 9, ABDE four points form a quadrilateral. Referring to fig. 10, three points of the CFG form a triangle.

A triangle formed by the three points ABC ensures that the first force transmission rod 13 does not move up and down through the stability of the three angles, so that the force transmission of the first force transmission rod is more stable. The triangle formed by the three points of the CDE controls the head rest connecting rod 17 not to shake backwards. The ABDE four points form a quadrangle to ensure the stable operation of the head rest plate connecting rod 17. The triangle formed by the three points CFG and the self-locking force of the driving element 6 control the stability of the point C. A four-bar linkage and three triangle-shaped and driving piece 6 from the locking power support each other, restrict each other, through driving piece 6 complete open mode can through spacing complete control by the head board connecting rod 17 not rock, satisfy the sofa by the head in the user demand that does not rock in the use.

The headrest connecting rod 17, the transmission assembly 18 and the driving member 6 are integrally formed as a whole because they are all mounted on the back frame connecting rod 16. When the module is installed on the sofa, the module can be spliced outside, and then the module is directly installed on the side plate 11, so that the operation is convenient.

Referring to fig. 11, in order to make the headrest plate connection link 17 more stably rotate along a predetermined trajectory, the back frame connection link 16 is provided with a stopper shaft 22 toward the headrest plate connection link 17. The outer wall of the headrest plate connecting rod 17 is provided with a limiting groove 21 matched with the limiting shaft 22, and the limiting shaft 22 is embedded in the limiting groove 21. When the headrest plate connecting rod 17 rotates relative to the back frame connecting rod 16, the inner wall of the limiting groove 21 abuts against the limiting shaft 22 and rotates around the outer wall of the limiting shaft 22. One end of the limiting shaft 22, which is far away from the back frame connecting rod 16, is provided with a limiting plate 4, and the limiting plate 4 abuts against the headrest plate connecting rod 17.

The implementation principle of the sofa backrest which is prevented from being clamped and not exposed in the embodiment of the application is as follows:

1. in the initial state, the head rest part 8 is abutted against the upper end face of the back part 9, and the head rest part 8 is more suitable for supporting a pedestrian when the face of the person is upward in a lying posture;

2. if the position of the headrest 8 relative to the rear back 9 needs to be adjusted, the driving member 6 gives a driving force to the first power transmission lever 13, so that the first power transmission lever 13 rotates, and the guide shaft 20 slides in the guide groove 19. Due to the rotation of the first transmission rod 13, the headrest plate connecting rod 17 rotates relative to the back frame connecting rod 16, so that the headrest plate 2 is driven, and the headrest part 8 is adjusted;

3. when the head rest 8 is parallel to the backrest 7, no exposed element or metal part exists between the head rest 8 and the back rest 9, so that potential safety hazards of clamping hands do not exist;

4. simultaneously, a four-bar linkage and three triangle-shaped and driving piece 6 from the locking power support each other, restrict each other, do not rock around by head plate connecting rod 17 when coupling assembling 5 rises to expand completely, improved use comfort.

The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims

1. The utility model provides a prevent pressing from both sides unexposed sofa back which characterized in that: comprises that

A back frame wooden frame (1);

the headrest plate (2) is rotatably connected to the upper end of the back frame wooden frame (1) through a connecting component (5);

the driving piece (6) is arranged in the back frame wooden frame (1) and is used for providing a linear pair to drive the headrest plate piece (2) to rotate relative to the back frame wooden frame (1);

the lower back (3) is fixedly arranged on one side of the back frame wooden frame (1), and the headrest plate (2) and the lower back (3) are positioned on the same side of the back frame wooden frame (1);

the back frame wood frame is characterized by comprising a covering sleeve, wherein the covering sleeve is provided with a covering back frame wood frame (1), a headrest plate (2) and a lower back (3), and a filling layer used for increasing the softness of the headrest is arranged in the covering sleeve.

2. The sofa backrest as claimed in claim 1, wherein the sofa backrest is characterized in that:

the connecting assembly (5) comprises

A back frame connecting rod (16);

the headrest plate connecting rod (17), the headrest plate connecting rod (17) is fixedly connected to the headrest plate (2), and the headrest plate connecting rod (17) is rotatably connected to the back frame connecting rod (16);

the two ends of the transmission assembly (18) are respectively connected with the back frame connecting rod (16) and the headrest plate connecting rod (17) and used for converting the force of the driving piece (6) into a rotating pair which is connected with the headrest plate connecting rod (17) and rotates relative to the back frame connecting rod (16);

the back frame wooden frame (1) comprises

The top plate (10) is provided with a through groove for the upper end of the transmission assembly (18) to penetrate through the top plate (10);

the side plates (11) are fixedly connected to the two sides of the top plate (10), and the connecting assembly (5) is positioned between the two side plates (11);

and the fixing rod (12) is positioned between the two side plates (11) and is used for fixedly connecting the two side plates (11).

3. The sofa backrest as claimed in claim 2, wherein the sofa backrest is characterized in that: the headrest plate (2) is positioned right above the two side plates (11) in a closed state.

4. The sofa backrest as claimed in claim 3, wherein the sofa backrest is characterized in that: the transmission assembly (18) comprises a first transmission rod (13) and a second transmission rod (14), one end of the first transmission rod (13) is rotatably connected to the headrest plate connecting rod (17), the output end of the driving piece (6) is rotatably connected to the first transmission rod (13), one end of the second transmission rod (14) is rotatably connected to the first transmission rod (13) and the other end of the second transmission rod is rotatably connected to the back frame connecting rod (16), and one end, far away from the first transmission rod (13), of the driving piece (6) is rotatably connected to the back frame connecting rod (16); a guide groove (19) is formed in the first force transmission rod (13), and a guide shaft (20) which is slidably embedded in the guide groove (19) is arranged on the back frame connecting rod (16).

5. The sofa backrest as claimed in claim 4, wherein the sofa backrest is characterized in that: establish the tie point of first dowel steel (13) and second dowel steel (14) is A, establishes the tie point of second dowel steel (14) and back of the body frame connecting rod (16) is B, establishes the tie point of the output of first dowel steel (13) and driving piece (6) is C, and ABC three point formation triangle-shaped.

6. The sofa backrest as claimed in claim 5, wherein the sofa backrest is characterized in that: establish the tie point of first force transmission pole (13) and back of the body board connecting rod (17) is D, establishes the tie point of back of the body board connecting rod (17) and back of the body frame connecting rod (16) is E, and the CDE three point forms triangle-shaped.

7. The sofa backrest as claimed in claim 6, wherein the sofa backrest is characterized in that: the ABDE four points form a quadrilateral.

8. The sofa backrest as claimed in claim 7, wherein the sofa backrest is characterized in that: and the central point of the section of the guide shaft (20) is set as F, the connecting point of the driving piece (6) and the back frame connecting rod (16) is set as G, and the three points of the CFG form a triangle.

9. The sofa backrest as claimed in claim 5, wherein the sofa backrest is characterized in that: coupling assembling (5) are equipped with two sets ofly and are located respectively by head plate (2) both sides, driving piece (6) are equipped with one and are connected with one of them of two sets of coupling assembling (5).

10. The sofa backrest as claimed in claim 4, wherein the sofa backrest is characterized in that: an installation seat (15) is arranged between the back frame connecting rod (16) and the driving piece (6), the installation seat (15) is detachably connected to the back frame connecting rod (16), and the driving piece (6) is rotatably connected to the back frame connecting rod (16) through the installation seat (15); the back frame connecting rod (16) is fixedly installed on the back frame wooden frame (1) through a screw, and the headrest plate connecting rod (17) is fixedly installed on the headrest plate (2) through a screw.