Chair with seat pan having variable tilt

Abstract

In the present invention, the tilted state of a seat pan for a chair sequentially changes 360 degrees by simple operation such that the pelvis or spinal part is dynamically twisted according to the tilt of the seat pan even when sitting on the chair, and thus chair-related disorders occurring in workers that work while sitting in chairs for a long time can be prevented and fatigue can be reduced. As a means for solving the problem, the present invention comprises a chair having a seat pan provided on a lower support so as to freely rotate, wherein the seat pan is divided into a lower support plate and an upper support plate, an eccentric rotation operation plate is provided between the lower support plate and the upper support plate and is rotated by a motor, a thrust bearing is provided between the upper and lower support plates and the eccentric rotation operation plate such that an eccentric operation disk provided between the upper and lower support plates freely rotates, and an inclined circular protrusion part is provided on the upper surface of the eccentric rotation operation plate such that, when the eccentric rotation operation plate rotates, only tilting is sequentially tilted 360 degrees by the angle of inclination of the inclined circular protrusion part while which the upper support plate remains stationary.

Description

A chair with a variable seat incline

[0001] The present invention allows the seat of a chair to gradually change 360° into a tilted state by a simple operation, thereby dynamically twisting the pelvis and spine along the tilted seat while sitting on the chair, thereby preventing chair disease that occurs in office workers who sit on a chair for long periods of time and reducing fatigue.

[0002] Chairs used in offices and other places are generally composed of a seat and a lower support that supports the seat. In the case of chairs with a backrest that are commonly used, they are composed of a seat that supports the buttocks and a backrest that supports the user's back.

[0003] The above-mentioned backrest chair may have a tilting device installed on the seat to allow the backrest to rotate in the forward and backward direction to comfortably support the user's back, and may also have a function to adjust the height of the seat or adjust the angle in the forward and backward direction.

[0004] In addition, once the height or angle of the chair is set, it remains set and must be reset if changed. In the case of general office workers, they have to sit for long periods of time to work.

[0005] As mentioned above, many people suffer from so-called chair disease when they sit for long periods of time at work. Chair disease is a term that refers to diseases caused by the habit of sitting for long periods of time, and symptoms include lumbar disc herniation, back pain, turtle neck syndrome, blood circulation problems, and carpal tunnel syndrome.

[0006] It is said that chair disease can be prevented and overcome by reducing the amount of time spent sitting as much as possible, moving the body frequently, loosening up the body with light stretching at set times, and frequently changing the posture while sitting.

[0007] However, it is true that it is difficult for office workers to take the above preventive measures.

[0008] When reviewing prior art related to angle adjustment of a chair, Korean Patent No. 10-0872907 entitled “Chair with adjustable angle of seat and backrest” (Patent Document 1), Korean Patent No. 10-2222629 entitled “Apparatus for adjusting seat angle of a chair” (Patent Document 2), and Korean Patent No. 10-2596301 entitled “Apparatus for adjusting seat angle for a chair” (Patent Document 3) have been provided.

[0009] When examining the technical contents of the above patent document 1, it relates to the field of chairs, and more specifically, it relates to a chair in which the angle of the seat and backrest can be adjusted, which increases convenience of use by arbitrarily adjusting not only the user's back but also the angle of the seat, which supports the user's back directly using the backrest rather than using an auxiliary backrest, which has a relatively simple installation structure, and which provides a relatively soft sitting feeling by using a gas cylinder rather than a spring.

[0010] In addition, when examining the technical contents of patent document 2, it relates to a seat angle adjustment device for a chair that allows the seat installed on the chair to rotate and be adjusted according to the seat angle preferred by the chair user, so that the chair user can straighten his / her back when performing work, and when resting, the seat angle is adjusted comfortably according to the chair user's resting posture, so that the chair user can rest comfortably without the lower body of the chair user slipping.

[0011] When examining the technical contents of Patent Document 3, it is a seat angle adjustment device that is provided with a separate angle adjustment device positioned between the lower support body and the seat of various chairs, so that the seat can be adjusted to various angles from a horizontal state by the angle adjustment device, and thus, depending on the form or purpose of use of the chair, the seat angle can be changed and maintained to the most optimal seat angle or can be quickly returned to a horizontal state.

[0012] In the case of the chairs disclosed in the above patent documents 1 to 3, the angle of the seat is adjusted forward and backward, and since the angle is maintained once set, there is a problem in that it is not helpful in preventing chair disease because the user who sits on the chair and works cannot induce body movement through the chair.

[0013] The present invention allows the seat of a chair to be incline sequentially changed 360° by a simple operation, thereby dynamically tilting the pelvis and spine according to the incline of the seat even while sitting on the chair, thereby preventing chair disease that occurs in office workers who sit on a chair for long periods of time and reducing fatigue.

[0014] As a means for solving the above problem, the present invention comprises a chair in which a seat is freely installed to rotate on a lower support body, wherein the seat is configured separately as a lower support plate and an upper support plate, and an eccentric rotation operating plate is installed therebetween to rotate by a motor, wherein a thrust bearing is installed between the upper and lower support plates and the eccentric rotation operating plate so that the eccentric rotation disc installed between the upper and lower support plates can rotate freely, and an inclined circular protrusion is configured on the upper surface of the eccentric rotation operating plate so that when the eccentric rotation operating plate rotates, the upper support plate is sequentially tilted 360° due to the angle of inclination of the inclined circular protrusion while stationary.

[0015] The present invention comprises a chair having a seat freely rotatably installed on a lower support body, wherein the seat is configured separately into a lower support plate and an upper support plate, and an eccentric rotation actuating plate is installed therebetween to be rotated by a motor, and a thrust bearing is installed between the upper and lower support plates and the eccentric rotation actuating plate so that the eccentric rotation actuating plate can freely rotate, and an inclined circular protrusion is configured on the upper surface of the eccentric rotation actuating plate so that when the eccentric rotation actuating plate rotates, the upper support plate is sequentially incline 360° according to the incline angle of the inclined circular protrusion while stationary, so that even when sitting on a chair, the pelvis or spine is dynamically rotated according to the incline of the seat, thereby preventing chair diseases that occur in office workers who sit on chairs for long periods of time and reducing fatigue.

[0016] Figure 1: Side cross-sectional view of the chair of the present invention

[0017] Figure 2: A diagram showing the state in which the eccentric rotation operating plate is rotated 180° in the state in Figure 1 and the seat is tilted backward.

[0018] Figure 3: Enlarged cross-sectional view of the main body of Figure 1

[0019] Figure 4: Enlarged cross-sectional view of the main body of Figure 2

[0020] Figure 5: Exploded view of Figure 3

[0021] Figure 6: Plan view of the main body of the present invention

[0022] Figure 7: Planar configuration diagram of the upper support plate of the present invention

[0023] Figure 8: Connection configuration diagram of the upper and lower support plates configured in the present invention.

[0024] Figure 9: Planar configuration diagram of the eccentric rotation operating plate of the present invention.

[0025] Figure 10: Cross-sectional view of the eccentric rotating operating plate of the present invention.

[0026] Figure 11: Bottom view of the eccentric rotation operating plate of the present invention

[0027] Figure 12: Planar configuration of the lower support plate of the present invention

[0028] Figure 13: Cross-sectional view of the lower support plate of the present invention

[0029] Figure 14: Side view of the disassembled state of the chair frame of the present invention.

[0030] Figure 15: Front view of the chair frame of the present invention

[0031] (Explanation of symbols)

[0032] (10)--Chair (20)--Lower support

[0033] (21)--Bridge support axis (22)--Bridge

[0034] (23)--Fixed bracket (24)--Elevating shaft

[0035] (30)--Left plate (40)--Upper support plate

[0036] (41)--Cushion (42)--Bearing Hold

[0037] (43)--Spherical bearing (44)--Connecting shaft rod

[0038] (45)--fastening nut (50)--lower support plate

[0039] (51)--Fastening hole (52)--Bearing groove

[0040] (53)--Protrusion (54)--Bolt

[0041] (55)--Nut (56)--Operating gear

[0042] (57)--Lower thrust bearing (60)--Eccentric rotation operating plate

[0043] (61)--Axial bearing (62)--Inclined circular projection

[0044] (62-1)--low part (62-2)--high part

[0045] (63)--Bearing groove (64)--Guide groove

[0046] (65)--Upper thrust bearing (66)--Internal gear

[0047] (67)--Outer periphery (68)--Detection protrusion

[0048] (69)--Limit switch (70)--Chair frame

[0049] (71)--Left frame (72)--Back frame

[0050] (73)--Backboard (73-1)--Backboard

[0051] (74)--Auxiliary climbing frame (75)--Inner connecting bearing

[0052] (76)--Outer connecting bearing (77)--Connecting piece

[0053] (90)--Connecting rod (91)--Fixed piece

[0054] (92)--Connecting bolt (93)--Fixing nut

[0055] (94)--Spherical bearing

[0056] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0057] The present invention relates to a chair (10) in which a seat (30) is freely assembled and rotated on a lower support (20), and in particular, when the seat (30) is stationary, the upper support (40) sequentially changes the angle of inclination in a 360° direction, so that when sitting on the seat (30), the pelvis or spine is dynamically rotated along the inclination, thereby preventing chair disease, which is a concern for office workers who sit on a chair (10) for a long time, and reducing fatigue.

[0058] The lower support body (20) constituting the chair (10) of the present invention is configured with legs (22) radially formed on the side of the leg support shaft (21), and the lifting shaft bar (24) with the fixed bracket (23) fixedly installed on the leg support shaft (21) is assembled to be freely rotatable, which is no different from a general chair.

[0059] The present invention is to sequentially change the tilt of the seat (30) assembled on the lower support (20) constituting the chair (10) in a 360° direction by the user's operation.

[0060] The configuration of the seat (30) is as follows.

[0061] The seat (30) is composed of an upper support plate (40) on which a cushion (41) is installed, an eccentric rotation operating plate (60), and a lower support plate (50), and the configuration and assembly of these will be described in more detail.

[0062] The lower support plate (50) fixes the seat plate (30) to the lower support body (20) so that it can rotate, and at the same time, fastens the chair frame (70) to the lower surface. The chair frame (70) is composed of a seat frame (71) and a back frame (72).

[0063] The lower support plate (50) is configured in a rectangular shape like the seat plate (30), and is formed by pressing a steel plate, and a fastening hole (51) is drilled in an eccentric position in the center, and a protrusion (53) is formed in a circular shape with a bearing groove (52) formed at a certain distance from the fastening hole (51), and a slide bar bracket (81) is assembled and fixed on one side.

[0064] A slide bar (80) is installed movably on the slide bar bracket (81), and a connecting bearing (82) is installed on one end, and a horizontally assembled guide bearing (83) is installed on the other end.

[0065] The above lower support plate (50) is fixed with a bolt (54) and a nut (55) on a fixed bracket (23) formed on the upper side of the lifting shaft (24), and a reduction motor (M) is fixedly installed on one side of the lower surface, and the shaft of the reduction motor (M) is made to protrude above the lower support plate (50), and then the operating gear (56) is assembled and fixed.

[0066] Additionally, a lower thrust bearing (57) is installed in the bearing groove (52) formed in the protrusion (53).

[0067] The configuration of the eccentric rotation operating plate (60) assembled on the upper part of the lower support plate (50) is as follows.

[0068] FIGS. 9 to 11 are a plan view, a cross-sectional view, and a bottom view of an eccentric rotation operating plate (60), in which a shaft bearing (61) is installed in the center of the eccentric rotation operating plate (60), and an inclined circular protrusion (62) having a bearing groove (63) formed at a certain distance from the shaft bearing (61) is formed, and the inclined circular protrusion (62) is composed of a low portion (62-1) and a high portion (62-2) as in FIG. 10.

[0069] In addition, a guide groove (64) is formed on the outside of the inclined circular protrusion (62), and the guide groove (64) is formed eccentrically from the shaft bearing (61) as shown in FIGS. 9 and 10, so that the guide groove (64) located at the high part (62-2) of the inclined circular protrusion (62) is in contact with the inclined circular protrusion (62), and is positioned close to the shaft bearing (61), and the guide groove (64) located at the low part (62-1) of the inclined circular protrusion (62) is in contact with the outer surface (67) of the eccentric rotation operating plate (60), and is positioned far from the shaft bearing (61).

[0070] At this time, the guide bearing (83) of the slide bar (80) installed on the lower support plate (50) is fitted into the guide groove (64), and when the eccentric rotation operating plate (60) rotates, the slide bar (80) installed on the slide bar bracket (81) moves forward and backward by the guide bearing (83) fitted into the guide groove (64).

[0071] In addition, an upper thrust bearing (64) is positioned in a bearing groove (63) formed in an inclined circular protrusion (62), an internal gear (66) is formed on the lower edge of an eccentric rotation operating plate (60) to engage with an operating gear (56) formed in a lower support plate (50), and a detection protrusion (68) is formed on one side of an outer surface (67) of an eccentric rotation operating plate (60) to operate a limit switch (69) located on one side, thereby controlling the operation of a reduction motor (M).

[0072] The upper support plate (40) located on the upper part of the eccentric rotation operating plate (60) forms a bearing holder (42) in the central part, and a spherical bearing (43) formed on the upper part of the fastening shaft rod (44) is fitted into the bearing holder (42) and assembled. The fastening shaft rod (44) passes through the shaft bearing (61) of the eccentric rotation operating plate (60) and is fastened with a fastening nut (45), and a cushion (41) is installed on the upper part of the upper support plate (40).

[0073] The above cushion (41) can be fixedly installed on the upper support plate (40), but the cushion (41) can be easily replaced on the upper support plate (40) using a means such as magic tape, so that it can be easily replaced according to the user's preference or season.

[0074] As shown in FIG. 15, an auxiliary backrest frame (74) having an auxiliary backrest (73) installed on the inside of a backrest frame (72) constituting a chair frame (70) is connected, and the connection is made by connecting an inner connection bearing (75) formed on the backrest frame (72) and an outer connection bearing (76) formed on the outside of the auxiliary backrest frame (74) with a connection piece (77), and assembling a connection bearing (82) formed on the end of a slide bar (80) to the lower part of the auxiliary backrest frame (74), so that the auxiliary backrest (73-1) formed on the upper part of the auxiliary backrest frame (74) moves forward with the inner and outer connection bearings (75)(76) as an axis by the forward and backward operation of the slide bar (80) and then returns to its original position so as to be parallel to the backrest (73) formed on the backrest frame (72).

[0075] As shown in Fig. 8, a fixed piece (91) is fixedly installed on the front side of the lower surface of the upper support plate (40) and the rear side of the upper surface of the lower support plate (50), and a connecting bolt (92) that is movably connected to a connecting rod (90) through a spherical bearing (94) is inserted into the fixed piece (91), and then fastened with a fixing nut (93), and a wrinkle cover (94) is installed on the outer surface of the upper and lower support plates (40) (50) so that the interior is visually blocked.

[0076] In carrying out the invention, the operation of the reduction motor (M) for rotating the eccentric rotation operating plate (60) is performed in the control box, and the reduction motor (M) alternates between forward and reverse rotation, and the operation time, etc. can be arbitrarily set by a timer, and when the user stands up from the chair (10) during operation, the operation of the reduction motor (M) can be stopped, and various functions can be electrically set.

[0077] The main technology of the invention is that when the eccentric rotation operating plate (60) is rotated by the reduction motor (M), the inclination of the seat (30) is sequentially tilted 360°, allowing the user's pelvis or spine to be dynamically rotated according to the inclination of the seat (30).

[0078] The chair (10) of the present invention configured in this manner is no different from a chair for general business use in that it is used for the same purpose.

[0079] However, unlike conventional general chairs, the chair (10) of the present invention operates the reduction motor (M) when necessary during the process of sitting for a long time to work, thereby driving the operating gear (56) and causing the eccentric rotation operating plate (60) that is gear-coupled with the internal gear (66) to rotate about the fastening shaft (44) as an axis.

[0080] At this time, the lower support plate (50) is fixedly fastened on the fixing bracket (23) of the lower support body (20), and the upper support plate (40) is connected to the lower support plate (50) through a connecting rod (90) as shown in FIG. 8.

[0081] In addition, a lower thrust bearing (57) and an upper thrust bearing (65) are positioned between the lower support plate (50) and the eccentric rotation operating plate (60) and between the eccentric rotation operating plate (60) and the upper support plate (40), so that there is no problem with the rotational motion of the eccentric rotation operating plate (60) even when the positions of the upper and lower support plates (40)(50) are fixed.

[0082] Accordingly, when the state of the chair (10) is such that the high part (62-2) of the inclined circular protrusion (62) formed on the eccentric rotation operating plate (60) as shown in Fig. 1 is located at the rear of the seat (30), that is, at the guide bearing (83) part of the slide bar (80), and the low part (62-1) is located at the front, when the reduction motor (M) is operated, the eccentric rotation operating plate (60) rotates clockwise around the fastening shaft (44).

[0083] At this time, the eccentric rotation operating plate (60) is positioned with the high part (62-2) at the back of the seat (30), i.e., in the 3 o'clock direction, as shown in Fig. 9, and the low part (62-1) is positioned at the front of the seat (30), i.e., in the 9 o'clock direction, so that the seat (30) is maintained in an almost horizontal state.

[0084] At the same time, the guide bearing (83) of the slide bar (80) connected to the lower part of the auxiliary climbing frame (74) is located in the guide groove (64) formed at the shortest position (high part (62-2)) from the center of the fastening shaft (44), and the auxiliary climbing plate (73-1) formed at the upper part of the auxiliary climbing frame (74) is positioned parallel to the climbing plate (73) of the climbing frame (72).

[0085] In the above state, when the eccentric rotation operating plate (60) rotates so that the high part (62-2) is positioned at the 6 o'clock direction, the low part (62-1) is positioned at the 12 o'clock direction, so that when sitting on the chair (10), the left part of the seat (30) is positioned high and the right part is positioned low, causing the pelvis and spine to be twisted to the right.

[0086] At this time, the guide bearing (83) of the slide bar (80) connected to the lower part of the auxiliary climbing frame (74) is pushed backward by the guide groove (64) that is slightly further away from the fastening shaft (44), and thus the auxiliary climbing plate (73-1) of the auxiliary climbing plate frame (74) moves inward from the climbing plate (73) to press the user's back.

[0087] When the eccentric rotation operating plate (60) rotates so that the high part of the inclined circular protrusion (62) is positioned at the 9 o'clock direction, the low part (62-1) is positioned at the 3 o'clock direction as shown in Fig. 2, so that the front of the seat (30) is high and the back is positioned low, causing the pelvis and spine to be tilted backward.

[0088] At the same time, the guide bearing (83) of the slide bar (80) connected to the lower part of the auxiliary climbing frame (74) is located in the guide groove (64) located furthest from the center of the fastening shaft (44) (lower part (62-1)), so the slide bar (80) moves backward as shown in Fig. 2.

[0089] As described above, when the slide bar (80) moves backward, the auxiliary backrest frame (74) connected thereto moves forward with the inner and outer connecting bearings (75) (76) and connecting piece (77) as the supporting plate (73-1) pushing and applying pressure to the user's waist, thereby obtaining the effect of applying pressure to the spine.

[0090] In addition, when the eccentric rotation operating plate (60) rotates and the high part (62-2) of the inclined circular protrusion (62) is positioned in the 12 o'clock direction, the low part (62-1) is positioned in the 6 o'clock direction, so when sitting on the chair (10), the left part of the seat (30) is positioned low and the right part is positioned high, causing the pelvis and spine to be tilted to the left.

[0091] In the above-described state, when the eccentric rotation operating plate (60) rotates so that the high part (62-2) is positioned again in the 3 o'clock direction as in Fig. 9, the eccentric rotation operating plate (60) rotates 360° and returns to its original state, and the seat (30) is maintained in an almost horizontal state as in Fig. 1.

[0092] As described above, when the eccentric rotating operating plate (60) that is gear-coupled with the operating gear (56) is slowly rotated by the operation of the reduction motor (M), the high part (62-2) and the low part (62-1) formed in the inclined circular protrusion (62) rotate, thereby changing the inclination of the seat (30) and dynamically twisting the user's pelvis and spine, so that it is expected that the prevention of chair disease that occurs when working while sitting on a chair (10) for a long time can be expected.

[0093] When the eccentric rotation operating plate (60) rotates and the high part (62-2) of the inclined circular protrusion (62) reaches the 3 o'clock direction as shown in FIG. 9, the protruding detection protrusion (68) on one side touches the limit switch (69), and at this time, the rotation of the reduction motor (M) is temporarily stopped and then reversed to rotate the eccentric rotation operating plate (60) counterclockwise, repeating the operation of rotating 360° in reverse.

[0094] As described above, the operating time of the reduction motor (M) that rotates the eccentric rotation operating plate (60) forward and backward is arbitrarily adjusted by the settings of the control box (C).

[0095] In addition, an upper thrust bearing (65) and a lower thrust bearing (57) are installed between the upper and lower support plates (40) (50) and the eccentric rotation plate (60), so that there is no problem with the rotation operation of the eccentric rotation plate (60) even when the positions of the upper and lower support plates (40) (50) are fixed.

[0096] The lower support plate (50) fixedly installed on the fixed bracket (23) of the lower support body (20) is connected to each other through a connecting rod (90) as shown in FIG. 8, and the connecting rod (90) is connected through a spherical bearing (94) assembled to the fixed piece (91) of the upper and lower support plates (40) (50), and there is a slight play in the left and right directions, so there is no problem in connecting and supporting the fixedly installed lower support plate (50) and the upper support plate (40) whose inclination changes with the connecting rod (90).

[0097] A wrinkle cover (94) is installed on the edges of the upper and lower support plates (40) (50), so that there is no problem in use even if the inclination of the seat (30) changes, and the cushion (41) formed on the seat (30) can be easily attached and detached using the upper support plate (40) and a means such as magic tape, so that it can be easily replaced according to preference and convenience, which is convenient.

Claims

1. In constructing a chair in which a seat plate with a chair frame coupled to a lower support member is freely installed for rotation, a lower support plate (50) is fixedly installed on a fixed bracket (23) of a lower support member (20), a bearing groove (52) is formed on the lower support plate (50), a lower thrust bearing (57) is installed in the bearing groove (52), a reduction motor (M) is installed on one side of the lower end of the lower support plate (50), an operating gear (56) formed on the reduction motor (M) is formed to protrude from one side of the upper surface of the lower support plate (50), an eccentric rotation operating plate (60) is placed on the lower support plate (50), an internal gear (66) is installed on the lower surface of the eccentric rotation operating plate (60) to be gear-coupled with the operating gear (56) of the reduction motor (M), and a low part (62-1) is formed on the eccentric rotation operating plate (60). A slanted circular protrusion (62) is formed by a high part (62-2), a bearing groove (63) is formed on the slanted circular protrusion (62), an upper thrust bearing (65) is installed on the bearing groove (63), an upper support plate (40) having a cushion (41) formed on an eccentric rotation operating plate (60) is installed, a fastening shaft rod (44) having a spherical bearing (43) fitted in the center of the upper support plate (40) is formed, and the fastening shaft rod (44) penetrates the eccentric rotation operating plate (60) and the lower support plate (50) and is then fastened and fixed with a fastening nut (45), so that the eccentric rotation operating plate (60) is installed rotatably between the upper and lower support plates (40) (50), and when the eccentric rotation operating plate (60) rotates, the eccentric rotation operating plate (60) is formed by a low part (62-1) and a high part (62-2). A chair with a changeable seat inclination, characterized in that the inclination of the upper support plate (40) is changed by a slanted circular protrusion (62).

2. A chair with a variable inclination of the seat, characterized in that in paragraph 1, a guide groove (64) is formed on the outer surface of the inclined circular protrusion (62) of the eccentric rotation operating plate (60), and the guide groove (64) is formed eccentrically from the center of the eccentric rotation operating plate (60) through which the fastening shaft rod (44) passes, and the guide groove (64) located at a lower portion (62-1) than the higher portion (62-2) of the circular inclined protrusion (62) is located farther from the center.

3. In the first paragraph, a chair frame (70) composed of a seat frame (71) and a back frame (72) is fixedly installed on the lower surface of the lower support plate (50), an auxiliary back frame (74) is positioned between the back frame (72), and then an inner connecting bearing (75) formed on the back frame (72) and an outer connecting frame (76) formed on the auxiliary back frame (74) are connected with a connecting piece (77), and a slide bar (80) movably installed on one side of the lower support plate (50) is connected to the lower end of the auxiliary back frame (74), and a guide bearing (83) is installed at the end of the slide bar (80), and the guide bearing (83) is fitted into a guide groove (64) formed on an eccentric rotation operating plate (60), so that when the eccentric rotation operating plate (60) rotates, the slide bar (80) moves forward and backward by the eccentrically configured guide groove (64). A chair with a changeable seat inclination characterized by the auxiliary backrest (73-1) of the auxiliary backrest frame (74) being moved forward and backward.

4. A chair with a variable seat inclination characterized in that, in paragraph 1, a fixed piece (91) is fixedly installed on an upper support plate (40) and a lower support plate (50), a connecting bolt (92) is installed on the fixed piece (91), and a connecting rod (90) is connected to the connecting bolt (92), wherein the connecting bolt (92) and the connecting rod (90) are assembled through a spherical bearing (94).

Images