Adjustable backrest device

Abstract

To provide an adjustable backrest device that is attached to a frame behind a bicycle seat, in the field of backrest devices. [Solution] A first angle adjustment unit 3 is provided at the connection point between the backrest component 1 and the arm structure, allowing for angle adjustment between the backrest component and the arm structure. A first length adjustment unit 2 is provided on the backrest component, allowing for vertical pulling of the backrest component, thereby meeting the rider's need for small-range height adjustment of the backrest component. A second length adjustment unit 41 is provided at the upper end of the arm structure, allowing for long-range adjustment of the backrest by pulling a telescopic rod 411 fixed to the backrest component, thereby meeting the rider's need for long-range height adjustment of the backrest component. Symmetrical arm support legs 4123 are provided at the lower end of the arm structure, each connected to a connecting plate and a second angle adjustment unit 6, allowing for angle adjustment relative to the horizontal connecting plate of the arm structure. A hollow elastic net cloth 11 is provided on the backrest, providing both breathability and elasticity. This device not only relieves tension and fatigue caused by posture, but is also safe and reliable.

Description

[Technical Field]

[0001] The present invention relates to the field of bicycle seat backrests, and more particularly to an adjustable backrest device. [Background technology]

[0002] Current motorcycles, electric bicycles, and bicycles lack a backrest behind the seat, leaving the rider with no support for their back, forcing them to maintain a slightly bent posture at all times. Long rides leave the muscles and nerves unable to relax, resulting in extreme fatigue. While some motorcycles and electric bicycles have a low rear fixing ring, the height and angle cannot be adjusted, and the long seat makes it difficult to lean directly against it. When carrying children behind the rider, accidents involving children falling to the ground at high speeds, especially during acceleration, are common and extremely dangerous. Therefore, there is a strong demand for a backrest that can be adjusted in height and angle and can provide tailored support for the lower back and back. Summary of the Invention [Problem to be solved by the invention]

[0003] The present invention discloses an adjustable backrest device, and aims to solve the technical problems existing in the prior art. [Means for solving the problem]

[0004] The present invention employs the following technical means: an adjustable backrest device attached to a frame behind a bicycle seat, comprising a backrest part, an arm structure and a connecting plate unit connected in series.

[0005] A first angle adjustment portion is provided at the connection point between the backrest component and the arm structure, and the first angle adjustment portion has a first rotating portion connected to the backrest component and a first fixed portion connected to the arm structure, which fit together. A first length adjustment portion is provided between the backrest component and the first rotating portion, and an elastic net surface is provided on the side of the backrest component facing the back.

[0006] A second length adjustment part is provided at the upper end of the arm structure, and the second length adjustment part has an extensible rod fixed to the first fixed part.

[0007] The arm support legs provided symmetrically at the lower end of the arm structure are connected to the connecting plate unit by second angle adjustment parts, respectively, making it possible to adjust the relative angle between the arm structure and the connecting plate unit.

[0008] In some embodiments, the first angle adjustment part includes the first rotating part, the first fixed part, a first central axis passing through the first rotating part and the first fixed part, and a positioning bead simultaneously arranged inside the first rotating part and the first fixed part, wherein one end of the positioning bead is fixedly attached to the first rotating part and the other end is movably connected to an attachment hole provided in the first fixed part.

[0009] In some embodiments, the first rotating part and the first central shaft are loosely fitted, a plurality of positioning holes are provided on the contact surface of the first fixed part with the first rotating part, and a first passage is provided between the positioning holes, and when the first rotating part rotates relative to the first fixed part, the first rotating part drives the positioning bead to move along the positioning holes and the first passage to a predetermined positioning hole and reach a predetermined angle.

[0010] In some embodiments, a connecting end fixed to the arm structure is fixed to the lower end of the first fixed part, and an upper end of the first rotating part is fixed to the backrest part via the first length adjustment part, so that the backrest part and the arm structure can rotate at a predetermined angle.

[0011] In some embodiments, the first length adjustment part includes a gear position member and a slide adjustment member that slide relative to each other, the gear position member has a plurality of communicating first gear position holes along a vertical direction, and the slide adjustment member has a positioning card member that is fitted into the first gear position holes so that the positioning card member can move along the plurality of first gear position holes to a predetermined length.

[0012] In some embodiments, the gear position member is fixedly attached to the backrest component, gear position grooves are provided on both sides of the first gear position hole, a mounting plate to which the positioning card member is fixed is slidably connected to the gear position grooves, and the mounting plate is fixed integrally with the first rotating part.

[0013] In some embodiments, the second length adjustment part includes a telescopic rod having a plurality of second gear position holes arranged in a vertical direction, an arm slidably fitted with the telescopic rod, and a telescopic button movably attached to the arm and fitted with the second gear position holes, wherein the upper end of the telescopic rod is fixed to the connecting end, and the lower end is inserted into and attached to the arm cavity of the arm, a second passage is provided between the second gear position holes, and a spring is provided in the telescopic button, so that the telescopic rod and the arm undergo a predetermined displacement when the telescopic button is pressed.

[0014] In some embodiments, the telescopic button includes a stopper block, a button shaft, and a pressing end fixed in order, the stopper block being disposed in the inner cavity of the telescopic rod, the button shaft fitted with a compression spring being disposed horizontally in the second gear position hole, and the pressing end being disposed in a recess provided on the outer side of the arm.

[0015] In some embodiments, the second angle adjustment unit includes an outer cover, a stand, and a button support ring connected in sequence via a second central axis, and a locking rod passing through the outer cover and the stand, wherein the stand has a plurality of locking angle holes and a passage connecting the adjacent locking angle holes, the locking rod passes through the outer cover, the stand, and the arm support leg in sequence and is pressed against the button support ring, the stand is fixed to a connecting plate provided on the connecting plate unit, and when the arm support leg rotates around the second central axis, the locking rod is driven to move within the plurality of locking angle holes.

[0016] In some embodiments, the connecting plate has fixedly attached thereto a connecting cuff that fixedly connects to the frame. [Effects of the Invention]

[0017] The present invention discloses an adjustable backrest device, which has the following advantages over the prior art:

[0018] The adjustable backrest device has a first angle adjustment section at the connection point between the backrest component and the arm structure, the first angle adjustment section having a first rotating section connected to the backrest component and a first fixed section connected to the arm structure. Rotating the first rotating section manually creates an angle between the backrest component and the arm structure, thereby satisfying the desired inclination of the backrest component. A first length adjustment section is provided between the backrest component and the first rotating section, the first length adjustment section including a gear positioning member and a slide adjustment member that slide relatively, the gear positioning member being fixed to the backrest component and the slide adjustment member being fixed integrally with the first rotating section. Pulling the backrest component vertically manually creates a displacement between the backrest component and the slide adjustment member, allowing the height of the backrest component to be adjusted over a small range, satisfying the rider's need for fine adjustment of the backrest component. The upper end of the arm structure is equipped with a second length-adjusting section. This section includes a telescopic rod fixed to the first fixed section and a telescopic button movably attached to the arm and fitted with the telescopic rod's second gear positioning hole. The telescopic rod drives the backrest component to achieve long-range adjustment of the arm, satisfying the rider's height and needs. The arm support legs, symmetrically arranged at the lower end of the arm structure, are connected to a connecting plate unit and a second angle-adjusting section, respectively, allowing for relative angle adjustment between the arm structure and the connecting plate unit. The arm drives the backrest component to achieve overall angle adjustment, providing back and lumbar support. The backrest component is fitted with a hollow elastic net fabric on the side that adheres to the back, providing breathability and protection against injury. This device not only meets the rider's back and lumbar support needs, but also relieves tension and fatigue caused by posture and effectively prevents the rider behind the rider from falling due to acceleration, providing comfort and safety. [Brief explanation of the drawings]

[0019] In order to more clearly explain the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings necessary for explaining the embodiments, which are part of the present invention, and the schematic embodiments of the present invention and their descriptions are for the purpose of interpreting the present invention, but are not intended to unduly limit the present invention.

[0020] [Figure 1] 1 is a structural schematic diagram of a technical solution according to an embodiment of the present invention; FIG. [Figure 2] FIG. 10 is a structural schematic diagram showing the first length adjustment part and the second length adjustment part both in an extended state. [Figure 3] FIG. 10 is a structural schematic diagram showing the state in which the arm is in a horizontal position and the backrest part supports the lower back. [Figure 4] FIG. 10 is a structural schematic diagram showing a state in which the first angle adjustment unit and the second angle adjustment unit are both at a predetermined angle. [Figure 5] FIG. 3 is a cross-sectional view of FIG. 2 taken along line MM. [Figure 6] 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 7] 3 is a cross-sectional view of FIG. 2 taken along line B-B. [Figure 8] FIG. 8 is a view seen from the direction G in FIG. 7. [Figure 9] FIG. 2 is an enlarged view of Q in FIG. [Figure 10] NN cross-sectional view of FIG. 3. [Figure 11] FIG. 11 is a cross-sectional view of FIG. 10 taken along the line F-F. [Figure 12] FIG. 4 is a structural schematic diagram of the outer cover of FIG. 3. [Figure 13] 5 is a cross-sectional view of FIG. 4 taken along line S-S. [Figure 14] FIG. 5 is a view seen from the direction E in FIG. 4. [Figure 15] FIG. [Figure 16] FIG. 16 is a view seen from the direction P in FIG.

[0021] Explanation of symbols in the figure: backrest part 1; net cloth 11; net frame 12; first length adjustment part 2; gear positioning part 21; first gear positioning hole 211; gear positioning groove 212; slide adjustment part 22; positioning card part 221; mounting plate 222; first angle adjustment part 3; first rotation part 31; first fixed part 32; positioning hole 321; first passage 322; connecting end 323; positioning bead 33; first central axis 34; arm structure 4; second length adjustment part 41; telescopic rod 411; second gear positioning hole 4111; second passage 4112; telescopic rod inner cavity 4113; arm 412; recess 4121; arm inner cavity 4122; arm support leg 4123; telescopic button 413; compression spring 4131; stopper block 4132; button shaft 4133; pressing end 4134; warning light 5; Second angle adjustment part 6; outer cover 61; through hole 611; second central axis 62; lock rod 63; lock stopper head 631; cylindrical neck 632; button support ring 64; connecting plate unit 7; connecting plate 71; stand plate 72; lock angle hole 721; second passage 722; connecting ring 73; connecting cuff 74; frame 8; fastening member 9. DETAILED DESCRIPTION OF THE INVENTION

[0022] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. In the description of the present invention, the term "including" is an open term and should be interpreted as "including but not limited to." The term "plurality" refers to two or more.

[0023] In describing the present invention, orientations or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on orientations or positional relationships shown in the drawings, and are merely for the purpose of explaining and simplifying the present invention, and do not indicate or imply that the devices or components shown have a specific orientation or must be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

[0024] Obviously, the described embodiments are only some of the embodiments of the present invention, but not all of the embodiments, and all other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without any creative efforts are included in the scope of protection of the present invention.

[0025] As shown in FIGS. 1 to 16, the technical solutions disclosed in the present invention are as follows:

[0026] The adjustable backrest device is attached to a frame 8 behind a bicycle seat and comprises a backrest part 1, an arm structure 4 and a connecting plate unit 7, which are connected in sequence. A first angle-adjusting part 3 is provided at the connection point between the backrest part 1 and the arm structure 4. The first angle-adjusting part 3 has a first rotating part 31 connected to the backrest part 1 and a first fixed part 32 connected to the arm structure 4, which fit together. A first length-adjusting part 2 is provided between the backrest part 1 and the first rotating part 31. A net surface made of elastic net cloth 11 is provided on the side of the backrest part 1 facing the back. A second length-adjusting part 41 is provided at the upper end of the arm structure 4, and the second length-adjusting part 41 has an extensible rod 411 fixed to the first fixed part 32. The arm support legs 4123 provided symmetrically at the lower end of the arm structure 4 are each connected to the connecting plate unit 7 by a second angle adjustment part 6, making it possible to adjust the relative angle between the arm structure 4 and the connecting plate unit 7.

[0027] The present invention provides a preferred embodiment, as shown in Figures 1 to 16: an adjustable backrest device attached to a frame 8 behind a bicycle seat, comprising a backrest part 1, an arm structure 4 and a connecting plate unit 7 connected in series.

[0028] 14 to 16, the backrest part 1 includes a net frame 12 and a net cloth 11 fixedly attached to one side by fastening members 9. The net frame 12 includes a middle beam and ventilation holes provided symmetrically on both sides, the part that rests against the back is arc-shaped, and the hollow elastic net cloth 11 is breathable and does not injure the body. A gear position member 21 provided on the first length adjustment part 2 is fixed to the beam on the back by the fastening members 9.

[0029] A first angle adjustment part 3 is provided at the connection point between the backrest part 1 and the arm structure 4, and the first angle adjustment part 3 includes a first rotating part 31 connected to the net frame 12 of the backrest part 1 and a first fixed part 32 connected to the arm structure 4, which fit together, a first central axis 34 passing through the first rotating part 31 and the first fixed part 32, and a positioning bead 33 simultaneously arranged inside the first rotating part 31 and the first fixed part 32, the positioning bead 33 being a sphere. One end of the positioning bead 33 is fixedly attached to a groove provided in the first rotating part 31, and the other end is movably connected to a positioning hole 321 provided in the first fixed part 32.

[0030] The first rotating part 31 and the first central shaft 34 are loosely fitted together and are rotatable around the first central shaft 34. The upper end of the first rotating part 31 is integrally fixed to a slide adjustment member 22 provided on the first length adjustment part 2, and when the first rotating part 31 rotates, the backrest part 1 connected to the first length adjustment part 2 is driven to rotate, thereby enabling angle adjustment of the backrest part 1.

[0031] 4, three positioning holes 321 are provided on the contact surface of the first fixed part 32 with the first rotating part 31, and a first passage 322 is provided between two adjacent positioning holes 321. The centers of the three positioning holes 321 and the first passage 322 are on the same circle, and the center of the circle coincides with the center of the first fixed part 32. When the backrest part 1 is rotated by hand, the first rotating part 31 rotates relative to the first fixed part 32, and the first rotating part 31 drives the positioning beads 33 to move along the positioning holes 321 and the first passage 322, thereby realizing angle adjustment of the arm structure 4 of the backrest part 1 toward or away from the rider's back. The arm structure 4 can be rotated to a predetermined positioning hole 321 according to needs until a predetermined angle is reached.

[0032] It should be noted here that the number of positioning holes 321 can be set according to needs.

[0033] A first length adjustment part 2 is provided between the backrest component 1 and the first rotating part 31. A connecting end 323 at the lower end of the first fixed part 32 is fixed to an extendable rod 411 provided on the arm structure 4 by a fastening member 9, and an upper end of the first rotating part 31 is connected to a slide adjustment member 22 provided on the first length adjustment part 2 to form an integrated unit.

[0034] The first length adjustment unit 2 includes a gear position member 21 and a slide adjustment member 22 that slide relative to each other, the gear position member 21 has a plurality of communicating first gear position holes 211 along the vertical direction, the slide adjustment member 22 has a positioning card member 221, the positioning card member 221 is fitted into the first gear position hole 211, and the positioning card member 221 moves along the first gear position hole 211 to a predetermined length.

[0035] 7 and 8, the gear position member 21 is fixed to the net frame 12 by fastening members 9, and gear position grooves 212 are provided symmetrically on both sides of the first gear position hole 211. The slide adjustment member 22 includes a positioning card member 221 that fits into the first gear position hole 211. The positioning card member 221 is fixed vertically to a mounting plate 222, and the mounting plate 222 is slidably connected to the gear position groove 212 and can move up and down along the gear position groove 212 to adjust the distance between the backrest component 1 and the arm structure 4 and meet the height needs of the rider.

[0036] 2 and 5, a second length adjustment part 41 is provided at the upper end of the arm structure 4, and the second length adjustment part 41 has an extendable rod 411 fixed to the first fixing part 32 by a fastening member, and a plurality of second gear position holes 4111 are provided in the extendable rod 411 in a vertical direction. An arm 412 provided on the arm structure 4 is fitted with the extendable rod 411, and the upper end of the extendable rod 411 is fixed to the connecting end 323 by a fastening member 9, and the lower end is inserted into an arm cavity 4122 of the arm 412. An extendable button 413 that fits into the second gear position hole 4111 is movably attached to the arm 412, and second passages 4112 are provided between adjacent second gear position holes 4111. The telescopic button 413 includes a stopper block 4132, a button shaft 4133, and a pressing end 4134, which are fixed in this order. The stopper block 4132 is disposed in a telescopic rod bore 4113 provided in the telescopic rod 411. The button shaft 4133 with a compression spring 4131 fitted thereon is horizontally disposed in the second gear position hole 4111. The pressing end 4134 is disposed in a recess 4121 provided on the outer side of the arm 412. When the pressing end 4134 is pressed, the compression spring 4131 drives the button shaft 4133 to move horizontally, and the stopper block 4132 enters the telescopic rod bore 4113, pulling the telescopic rod 411, thereby generating a displacement between the telescopic rod 411 and the arm 412. When the pressing end 4134 is released after reaching a predetermined length, the stopper block 4132 enters the second gear position hole 4111, and the telescopic rod 411 and the arm 412 are locked.

[0037] Arm support legs 4123 are provided symmetrically at the lower end of the arm structure 4, and the arm support legs 4123 are each connected to the connecting plate unit 7 by a second angle adjustment part 6, making it possible to adjust the relative angle between the arm structure 4 and the connecting plate unit 7.

[0038] A warning light 5 is attached at the midpoint between the two arm support legs 4123 to provide a warning.

[0039] The second angle adjustment unit 6 includes an outer cover 61, a stand 72, a button support ring 64, which are connected in sequence via a second central shaft 62, and a locking rod 63 that passes through the outer cover 61 and the stand 72. The stand 72 extends vertically upward from a horizontal connecting plate 71 provided on the connecting plate unit 7, and the stand 72 is provided with a plurality of locking angle holes 721 and second passages 722 that connect adjacent locking angle holes 721. In this embodiment, three locking angle holes 721 are provided, and the number can be freely set according to needs to achieve the desired angle adjustment.

[0040] 3 and 4, the lock rod 63 is passed through the outer cover 61, the stand 72, and the arm support leg 4123 in this order and connected by fastening members at the ends, and the top of the button support ring 64 is supported by the button support ring 64. A second central shaft 62 is passed through the centers of the outer cover 61, the stand 72, the arm support leg 4123, and the button support ring 64 and fixed by a fastening member 9. The stand 72 is fixed to the connecting plate 71, and a gap is provided between the bottom of the arm support leg 4123 and the upper surface of the connecting plate 71, and the arm support leg 4123 is fixed to the lock rod 63. When the arm structure 4 is pushed by hand, the arm support leg 4123 rotates around the second central axis 62, driving the locking rod 63 to move through the three locking angle holes 721 and the second passage 722 of the stand 72. The locking stopper head 631 on the locking rod 63 is positioned in the through hole 611 in the outer cover 61, and the cylindrical neck 632 moves along the locking angle holes 721 and the second passage 722. When the locking rod 63 reaches a certain locking angle hole 721 and the arm structure 4 reaches a predetermined angle, it stops moving and the locking rod 63 is locked in the locking angle hole 721.

[0041] The relative angle between the arm structure 4 and the connecting plate unit 7 can be adjusted, and the arm drives the backrest component 1 to achieve overall angle adjustment, providing support for the back and waist. This not only meets the rider's need for support for the back and waist, but also relieves tension and fatigue caused by posture and effectively prevents the person riding behind the rider from falling due to acceleration, providing comfort and safety.

[0042] 3, 4 and 13, in this embodiment, the connecting plate unit 7 includes a connecting plate 71 arranged horizontally at the bottom of the arm structure 4, a stand 72 fixed vertically to the connecting plate 71, a connecting ring 73 fixed to the frame 8 at the bottom of the connecting plate 71, and a connecting cuff 74 fixed to the frame 8 at the side end of the connecting plate 71, thereby enabling easy attachment and detachment to the frame of a motorcycle, electric bicycle, bicycle, etc.

[0043] Although the above describes the embodiments of the present invention with reference to the drawings, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely schematic and not limiting. Those skilled in the art can devise many forms under the inspiration of the present invention without departing from the spirit of the present invention and the scope protected by the claims, and all of these forms are within the scope of protection of the present invention.

Claims

1. 1. An adjustable backrest device attached to a frame behind a bicycle seat, comprising: A backrest part, an arm structure and a connecting plate unit are sequentially connected, a first angle adjustment part is provided at a connection point between the backrest part and the arm structure, the first angle adjustment part having a first rotating part connected to the backrest part and a first fixed part connected to the arm structure, which are fitted together, and a first length adjustment part is provided between the backrest part and the first rotating part, and an elastic net surface is provided on the side of the backrest part facing the back; a second length adjustment part is provided at an upper end of the arm structure, the second length adjustment part having an extensible rod fixed to the first fixed part; The arm support legs provided symmetrically at the lower end of the arm structure are connected to the connecting plate unit by second angle adjustment parts, respectively, making it possible to adjust the relative angle between the arm structure and the connecting plate unit. An adjustable backrest device.

2. The first angle adjustment unit includes the first rotating unit, the first fixed unit, a first central axis passing through the first rotating unit and the first fixed unit, and a positioning bead disposed simultaneously inside the first rotating unit and the first fixed unit, one end of the positioning bead being fixedly attached to the first rotating unit and the other end being movably connected to an attachment hole provided in the first fixed unit.

2. The adjustable backrest device of claim 1.

3. The first rotating part and the first central shaft are loosely fitted together, a plurality of positioning holes are provided on a contact surface of the first fixed part with the first rotating part, and first passages are provided between the positioning holes, and when the first rotating part rotates relative to the first fixed part, the first rotating part drives the positioning beads to move along the positioning holes and the first passages to a predetermined positioning hole and reach a predetermined angle.

3. The adjustable backrest device of claim 2.

4. A connecting end fixed to the arm structure is fixed to a lower end of the first fixed part, and an upper end of the first rotating part is fixed to the backrest part via the first length adjusting part, so that the backrest part and the arm structure can rotate at a predetermined angle.

4. The adjustable backrest device of claim 3.

5. The first length adjustment unit includes a gear position member and a slide adjustment member that slide relatively, the gear position member is provided with a plurality of first gear position holes that communicate with each other along a vertical direction, and the slide adjustment member is provided with a positioning card member that is fitted into the first gear position holes and is movable along the plurality of first gear position holes up to a predetermined length.

2. The adjustable backrest device of claim 1.

6. The gear position member is fixedly attached to the backrest component, and gear position grooves are provided on both sides of the first gear position hole. A mounting plate to which the positioning card member is fixed is slidably connected to the gear position grooves, and the mounting plate is fixed integrally with the first rotating part.

6. An adjustable backrest device according to claim 5.

7. The second length adjustment unit includes a telescopic rod having a plurality of second gear position holes arranged in a vertical direction, an arm slidably fitted with the telescopic rod, and a telescopic button movably attached to the arm and fitted with the second gear position holes, the upper end of the telescopic rod being fixed to the connecting end and the lower end being inserted into an arm cavity of the arm, a second passage being provided between the second gear position holes, and a spring being provided in the telescopic button, so that the telescopic rod and the arm are displaced to a predetermined extent when the telescopic button is pressed.

2. The adjustable backrest device of claim 1.

8. The telescopic button includes a stopper block, a button shaft, and a pressing end, which are fixed in this order. The stopper block is disposed in the inner cavity of the telescopic rod. The button shaft, on which a compression spring is fitted, is horizontally disposed in the second gear position hole. The pressing end is disposed in a recess provided on the outer side of the arm.

8. The adjustable backrest device of claim 7.

9. The second angle adjustment unit includes an outer lid, a stand, and a button support ring, which are connected in sequence via a second central axis, and a locking rod that penetrates the outer lid and the stand. The stand is provided with a plurality of locking angle holes and passages that connect the adjacent locking angle holes. The locking rod penetrates the outer lid, the stand, and the arm support leg in sequence and is pressed against the button support ring. The stand is fixed to a connecting plate provided on the connecting plate unit. When the arm support leg rotates around the second central axis, the locking rod is driven to move within the plurality of locking angle holes.

2. The adjustable backrest device of claim 1.

10. A connecting cuff is fixedly attached to the connecting plate to connect the frame.

10. The adjustable backrest device of claim 9.

Images