JP2014140765A - Chair with backrest - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lumbar support mechanism with excellent aesthetic appearance in a rocking chair with a backrest configured by stretching a support sheet to a back frame.SOLUTION: A backrest 5 comprises a back frame 13 and a support sheet 14, and the back frame 13 has light/right side members 13a. The support sheet 14 includes lumbar pads 15 disposed individually at the back of both left/right ends of a lumbar support part 14a. The lumbar pads 15 are attached to erection parts 22a of rear links 22, and, in locking, the erection parts 22a are retracted relative to back supports 10. The lumbar pads are separated to the left/right so as to prevent deterioration of the external appearance and prevent feeling of pushed-up applied against a body.

Description

  The present invention relates to a chair having a lumbar support function on the backrest, and in particular, a flexible support sheet (also called a net-like material, mesh-like material, or net-like material) is used for the backrest. The chair with the lumbar support function is suitable.

  In a chair, for example, as exemplified in Patent Documents 1 and 2, a backrest or a seat is structured such that a net-like (or mesh-like) support sheet is stretched around a frame, and the user's body is received by the support sheet. It has been broken. Advantages of using a support sheet for the seat and the backrest include excellent air permeability and moderate elasticity and excellent cushioning.

  On the other hand, in chairs, in recent years, the importance of supporting the user's lumbar part (particularly the part centered on the third lumbar vertebrae) from behind has been recognized. It is common to provide a curved lumbar support.

  The backrest using a net-like support sheet is also provided with a lumbar support function. In this case, basically, the back of the back frame on which the support sheet is stretched The lumbar support part is formed in the support sheet by making the part located in the contact curved in a convex shape in a side view, but in order to exert the lumbar support function more strongly, on the back side of the support sheet The pressing means (pressing member) is also arranged so that the height can be adjusted. An example thereof is disclosed in Patent Document 1.

JP 2004-49658 A JP 2002-119366 A

  By the way, although patent document 2 is provided with the press member which presses a net-shaped support sheet, this press member is arrange | positioned in the state which spreads greatly on the back side of a support sheet. On the other hand, the back of the net-like support sheet can be seen through even if there is a difference in the degree. However, when the lumbar support member is too conspicuous, there is a problem that the appearance is not always good.

  The present invention has been made in view of such a current situation, and intends to provide a more improved lumbar support mechanism.

  The present invention has a seat and a backrest, and the backrest has a lumbar support portion that hits the waist of a seated person, and the lumbar support portion of the backrest can be adjusted by a height-adjustable pressing means from behind. The target is a chair that supports it. And in invention of Claim 1, the said press means is isolate | separated into the two lumbar pads arrange | positioned on both right and left sides on both sides of the intermediate part of the backrest, and a person moves up and down on the left and right lumbar pads. An operation unit is provided.

The invention of claim 2 is a preferred development of claim 1, wherein the backrest has a structure in which a flexible support sheet is stretched on a back frame opened in the front-rear direction, while the lumbar pad is provided. The front surface of the is curved in a forward projecting shape in both a side view and a plan view.

  The invention of claim 3 is a specific example of claim 2. That is, in claim 1, the left and right portions of the back frame are configured by vertically long side members, the support sheet is attached to the outer end surface of the side member and covers the front surface of the side member, and The lumbar pad is disposed close to the side member.

  In the present invention, since the pressing means for pressing (supporting) the lumbar support portion of the backrest is separated into the left and right lumbar pads, the lumbar pads are not so conspicuous in the back view of the chair, and are therefore excellent in aesthetics.

  In particular, when a support sheet is used for the back as in claim 2, the lumbar pad does not stand out in the front view of the chair (front view) even if the support sheet is transparent, so the chair as a whole is refreshed. Therefore, it can be said that the present invention is more effective when a mesh-like support sheet is used. Further, since the lumbar pads are individually arranged in the present invention, there is an advantage that the vertical movement can be smoothly performed (there may be a case where the movement is long from side to side).

  Well, the seated person's waist and back naturally hit the backrest, but generally the width of the backrest is set to be larger than the width of the human torso. Often not in contact. In addition, a person's back and waist are rounded in plan view, and even when viewed from this plane, the left and right sides of the backrest are often not in contact with the person.

  Conventionally, the pressing member that supports the lumbar support portion is often arranged at a portion where the human body hits the backrest. For this reason, the human back or waist often hits the pressing member via the backrest. . In this case, when the backrest has a structure in which the cushion is stretched on the inner shoulder, the pressing member rarely gives a feeling of pushing up to the human body, but when the backrest is a support sheet type, the support sheet is thin, so the pressing member The hit feeling will be transmitted to the human body, and there is a concern that it may give a sense of incongruity.

  On the other hand, in the present invention, since the pressing means is composed of left and right lumbar pads, the lumbar pads can be arranged at the left and right end portions of the backrest where the human body hardly hits. It is possible to prevent or remarkably suppress receiving the hit feeling and obtain a comfortable feeling of use.

  When the backrest is of the support sheet type, the support sheet may be easily torn when the load is concentrated on a narrow portion. In this regard, if the lumbar pad is rounded in both the side view and the plan view as in claim 2, the contact area between the support sheet and the lumbar pad can be increased and the curvature of the support sheet can be increased. The durability of the support sheet can be improved. Further, since the frictional resistance can be reduced when the lumbar pad is moved up and down, the lumbar pad can be smoothly operated up and down.

In the case of claim 2, the lumbar pad can adopt, for example, a circular or elliptical shape when viewed from the front. However, when a vertically long shape is employed as in the first embodiment, the support sheet is elongated vertically. There is an advantage that a proper tension can be maintained over a range. In addition, the use of a long shape at the top and bottom makes the contact area between the lumbar pad and the support sheet larger without telling the user that the lumbar pad is touching, which is particularly excellent in terms of ensuring the durability of the support sheet. .

  There are various modes for attaching the support material to the back frame. When the support sheet is attached to the outer end surface of the side member (back frame) as in claim 2, the area of the backrest in the front view is directly determined by the support sheet. Since it can be used as a support area of the body, there is an advantage that a person with a large shoulder width can be stably supported. Furthermore, the lumbar pad can be arranged as close to the left and right outside of the backrest as much as possible without impairing the support function of the support seat. From this aspect as well, the user is prevented from receiving a feeling of hitting the lumbar pad. A comfortable feeling can be obtained.

(A) is a perspective view of the chair which concerns on embodiment, (B) is a partially broken front view of the backrest. It is a side view of a chair. It is a rear view of a chair. It is the isolation | separation perspective view seen from the front. It is the isolation | separation perspective view seen from the front. It is a separation perspective view for explaining a locking mechanism. (A) is a side view of the back frame, (B) is a plan view of the lumbar pad, and (C) is a front view of the lumbar pad. (A) is the isolation | separation side view of the principal part, (B) is the isolation | separation perspective view of the principal part. (A) is a perspective view of the upper part of a back support | pillar, (B) is a fractured perspective view of the side member in a back frame. (A) is a partial side view in a non-locking state, (B) is a partial side view in a locking state. FIG. 11 is a cross-sectional view taken along the line XI-XI in a state where the lumbar pad is slightly shifted downward in FIG. 10. It is a figure which shows 2nd Embodiment.

  Next, an embodiment of the present invention will be described with reference to the drawings. This embodiment is applied to a swivel chair often used for office work. First, FIGS. 1 to 11 show the first embodiment, and FIG. 12 shows the second embodiment. In the following description, the left and right words for specifying the direction are used, but the left and right directions are based on the direction in which the seated person faces. First, the first embodiment will be described.

(1). Outline of First Embodiment First, an outline of a chair according to the first embodiment will be described with reference to FIGS. 1A is a perspective view of a chair, FIG. 2B is a partially broken front view of a backrest, FIG. 2 is a side view, FIG. 3 is a rear view, and FIGS. 4 and 5 are viewed from the front. FIG. 6 is an exploded perspective view for explaining the locking mechanism.

  For example, as shown in FIGS. 1 to 3, the chair is disposed above the base 3 as a main element, a leg device 1 having a leg column 2 (gas cylinder), a base 3 fixed to the upper end of the leg column 2, and the base 3. A seat 4, a backrest 5, and a headrest device 6 attached to the backrest 5 as an optional item are provided. The leg 1 includes a plurality of branch legs 7 extending radially, and a caster is provided at the tip of each branch leg 7.

  A pair of left and right swing frames 8 are arranged on the left and right sides of the base 3. The swing frame 8 is composed of a base 9 that is tilted rearward in a posture close to horizontal when not rocked, and a back column 10 that rises from the rear end. The front end portion of the base portion 9 is connected to the base 3 by left and right longitudinal support shaft portions 11 so as to tilt backward (rotate) around the front end portion of the swing frame 8. The swing frame 8 employs a metal molded product such as aluminum die cast, but may be a resin molded product or a sheet metal product. The left and right swing frames 8 are connected by a joint frame 11 at a corner where the base 9 and the back column 10 are connected.

  The backrest 5 has a configuration in which a support sheet 14 is stretched on a back frame 13 having a substantially square shape when viewed from the front, and the back frame 13 is fixed to a column 10 of the swing frame 10 with screws (details will be described later). The back frame 13 is gently curved in side view so that the portion corresponding to the waist of the seated person is the front end in side view, and therefore the support seat 14 (or backrest 5) has a lumbar support portion 14a. . The lumbar pad 14 is in contact with the left and right sides of the lumbar support portion 14a of the support sheet 14 from the back side. The support sheet 14 is recessed in a forward concave shape in plan view. Further, the support sheet 14 of the present embodiment has an appearance of a vertically striped pattern in which vertically long sparse parts and dense parts are alternately arranged in the left-right direction, and the sparse part can be seen through back and forth.

The back frame 13 is a resin molded product. For example, as shown in FIG. 4, left and right side members 13 a extending in the vertical direction, upper members 13 b connected to the upper ends of the left and right side members 13 a, and lower ends of the left and right side members 13 a It consists of the lower member 13c connected to. Therefore, the back frame 13 has a substantially rectangular shape when viewed from the front. The upper member 13b and the lower member 13c are gently curved in a concave shape facing forward in plan view.

  As described above, the swing frame 10 is connected to the base 3 by the support shaft portion 11 so as to tilt backward with the front end portion as the center, but in this embodiment, the support shaft portion is used as the locking spring means. The torsion bar built in 11 is adopted. The left and right intermediate portions of the torsion bar are non-rotatably held by the base 3, and both left and right end portions are fixed to the front end portion of the swing frame 8. For this reason, the swing frame 8 tilts backward while torsionally deforming the torsion bar.

  The support shaft portion 11 protrudes greatly on the left and right outer sides of the base 3, and for this reason, the swing frame 8 is also arranged considerably outside the base 3. However, as can be understood from FIG. 3B, for example, the swing frame 8 is positioned on the inner side of the left and right outer surfaces of the seat 4. Therefore, the swing frame 8 does not interfere with human walking.

  The seat 4 has a resin inner shell (not shown), a cushion stretched on the upper surface thereof, and an outer shell 16 (see FIG. 6) for supporting the inner shell. The outer shell 16 of the seat 4 is attached to an intermediate member 17 disposed below the seat 4 so that it can be moved back and forth. The front bracket 18 is attached to the front of the intermediate member. The front bracket portion 18 and the base 3 are connected by a front link 20. The front link 20 is rotatably attached to a front support shaft 20 ′ inserted through the base 3. The upper end of the front link 20 is connected to a longitudinal auxiliary frame member 21. The auxiliary frame member 21 is held by the intermediate member 17 so as to be slidable back and forth, and the auxiliary frame member 21 moves integrally with the seat 4 (outer shell 19).

  As shown in FIGS. 4 to 6, a rear link 22 is disposed on the inner side surface of the swing frame 10. The rear link 22 has a substantially L shape in a side view similar to the swing frame 8, a standing portion 22 a extends along the inner surface of the back column 10 in the swing frame 8, and the rear link 22 is a standing portion. A pivot pin 23 (see FIG. 4) at a position slightly in front of the base of 22a. It is connected to the swing frame 8. The front end of the rear link 21 protrudes upward, and this is connected to the rear end portion of the auxiliary frame member 21 by a rear pin 24.

  Therefore, when the backrest 5 (and the swing frame 8) tilts backward, the seat 4 tilts backward while moving backward. On the inner side surface of the front and rear intermediate part of the swing frame 8, there is a guide slot that is slightly tilted backward with respect to the horizontal, while the intermediate member to which the seat 4 is attached is slidable in the guide slot. Guide pins 25 (see FIGS. 5 and 7) are provided. Since the guide pin 25 is guided by the guide elongated hole, the seat 4 is not independently retracted and tilted backward, and the interlocking relationship with the swing frame 8 is forced.

  When the seated person leans against the backrest 5, the standing portion 22 a of the rear link 22 also tilts backward, but also tilts relatively backward with respect to the back column 10. That is, the rate at which the upright portion 22a of the rear link 22 tilts backward is greater than the rate at which the back column 10 tilts backward. And the lumbar pad 15 mentioned above is attached to the upper end part of the standing part 22a in the rear link 22 so that height adjustment is possible. Accordingly, the lumbar pad 15 is retracted relative to the back column 10 at the time of locking, and for this reason, when the support sheet 14 is locked, the tension is loosened.

Now, when a person performs work / work such as personal computer operation in a non-locking state, it is preferable that the upper body supports the lumbar part from behind by the lumbar support part 14a of the support sheet 14. Therefore, in a non-locking state, it is preferable that the lumbar support portion 14a protrudes considerably forwardly convex in a side sectional view. On the other hand, if the lumbar support part 14a is in a state of being largely protruded and is shifted to the locking state, the waist part may be excessively pushed up. Therefore, in the present embodiment, the lumbar pad 15 is moved backward relative to the back column 10 during locking to loosen the tension of the support sheet 14.

  The headrest device 6 has left and right head columns 27 rising from the left and right inner surfaces of the side member 13a in the back frame 13 (only one head column 13b is shown in FIGS. 1A and 4). The headrest 28 is attached to the head column 27 so that the height can be adjusted.

  The head column 27 is connected to the side member 13a by a pin (or a bin) so as to rotate back and forth around a portion near its lower end, and the lower end of the head column 27 is connected to the rotation absorbing device 29. It is connected to the upright part 22a of the rear link 22 via. At the time of locking, the head column 27 rotates so that the upper part thereof moves forward. Accordingly, the seated person has an advantage that the display of the personal computer can be easily viewed without raising his / her head while being in a locked state, and there is no need to lift the book when reading. Further, the rotation absorbing device 29 has a built-in spring, and the head column 27 can be tilted backward against the spring.

(2) Peripheral portion of lumbar pad Next, the peripheral portion of the lumbar pad 15 will be described with reference to the drawings in FIG. 7A is a side view of the back frame 13, FIG. 7B is a plan view of the lumbar pad 15, FIG. 7C is a front view of the lumbar pad 15, and FIG. 9A is an exploded perspective view of the main part, FIG. 9A is a perspective view of the upper portion of the back column 10, FIG. 10B is a cutaway perspective view of the side member 13a in the back frame 13, and FIG. A) is a partial side view in the non-locking state, (B) is a partial side view in the locking state, and FIG. 11 is a cross-sectional view taken along the line XI-XI with the lumbar pad 15 slightly shifted downward in FIG. . First, the swing frame 8 and the joint frame 12 will be described.

  As described above, the swing frame 8 is an aluminum molded product. For example, as shown in FIG. 9 (A), the base 9 of the swing frame 8 is formed in a generally bowl-like shape that is open to the inside, and is formed in the inside. Reinforcing ribs are provided. In addition, a rectangular hole 31 (see FIG. 4) that opens outward and slightly protrudes outward is formed in a substantially middle portion of the base 9 of the swing frame 8. The square hole 31 is for attaching an armrest device, and is closed with a cover 32 (see, for example, FIG. 5) when the armrest device is not attached.

  For example, as shown in FIG. 6, the base 9 of the swing frame 8 is provided with a lower inside cover 34 for covering the rear link 22. For example, as clearly shown in FIGS. 9 and 11, the back column 10 includes a side plate 35 and a back plate 36. The side plate 35 extends in the front-rear direction in a plan view, but the back plate 36 is inclined so as to shift backward as it goes to the center of the backrest 5 in a plan view. Therefore, the back column 10 is deformed in a plan view. It is L-shaped. A low inward front rib 37 is formed at the front end of the side plate 35 in the back column 10. Therefore, the inside of the side plate 35 has a shallow groove shape. A group of reinforcing ribs 38 having the same height as the front ribs 37 is formed inside the side plate 35.

The reason why the back column 10 is formed in a modified L shape is that the upright portion 22a of the rear link 22 is arranged in a space surrounded by the side plate 35 and the back plate 36. The standing portion 22 a of the rear link 22 is covered with an upper inside cover 39. For example, as shown in FIG. 9A, a bracket portion 40 for attaching the upper inside cover 39 is provided on the upper portion of the back plate 36 in the back column 10. An inward rear rib 41 extending vertically is formed on the back plate 36 of the back column 10.

  As described above, the head column 27 tilts forward in conjunction with the rear tilt of the rear link 22, and the rotation absorbing device 29 is connected to the upper end of the standing portion 22 a in the rear link 22. In some cases, the headrest device 6 is not attached. In this case, for example, as shown in FIG. 11A, a top cap 42 is attached to the upper end of the back column 10. An engaging portion 43 for attaching the top cap 42 is provided on the inner surface of the upper end portion of the back plate 36 in the back column 10.

  For example, as shown in FIG. 11, the side member 13 a of the back frame 13 overlaps the back column 10 of the swing frame 8 from the left and right outer sides. The side member 13a has a substantially trapezoidal cross-sectional shape in which the front-rear width gradually decreases toward the left and right outer sides, and is inclined backward so that the front, the back, and the backrest 5 are displaced toward the rear as they approach the center.

  The outer peripheral surface of each member constituting the back frame 13 is a flat surface. And, as clearly shown as a representative of FIG. 11, a groove 46 is formed to extend long on the outer side surface (the outer peripheral surface of the back frame 13) of each member, and is fixed to the end edge of the support sheet 14. An edge member 47 is fitted into the groove 46. The edge member 47 is divided for each member.

  Since the support sheet 14 is attached to the outer peripheral surface of the back frame 13, the entire area of the front surface of the backrest 5 is a seating surface, and thus a person with a large shoulder width is stably supported. Further, since the back frame 13 is hidden behind the support sheet 14 (visible through), it has an appearance as if the entire back and backrest 5 are composed of the support sheet 14, and therefore, a unique aesthetic is provided. It is evident.

  Since the support sheet 14 is attached to the outer peripheral surface of the back frame 13, the entire area of the front surface of the backrest 5 is a seating surface, and thus a person with a large shoulder width is stably supported. Further, since the back frame 13 is hidden behind the support sheet 14 (visible through), it has an appearance as if the entire back and backrest 5 are composed of the support sheet 14, and therefore, a unique aesthetic is provided. It is evident.

  For example, as shown in FIG. 10, a portion of the side member 13a that overlaps the back column 10 has a groove shape that opens inward, and a plurality of reinforcing ribs 48 are provided inside. This is for example to equalize the wall thickness as much as possible to prevent sink marks during molding.

  As shown in FIG. 11, the back column 10 is fastened to the back column 10 with screws 49 and nuts 50. The screws 49 are inserted into the side plates 35 of the back column 10 from the inside, and the nuts 50 are fitted into the nut holes 51 of the front opening formed in the side members 13a and are held so as not to rotate. Since the nut hole 51 is opened to the front, the nut hole 51 is hidden by the support sheet 14 and is hardly visible, and therefore there is no problem in aesthetics. The side member 13a is fixed to the back column 10 at two positions on the upper and lower sides. For example, FIG. 5 shows a screw insertion hole 52 of the side member 13a.

(4) Lumber Pad Next, the lumbar pad 15 will be described. The lumbar pad 15 is a resin product, and for example, as shown in FIG. 7, the lumbar pad 15 is bent vertically and vertically so as to protrude forward in a side view and a plan view. For this reason, the support sheet 14 is smoothly supported without stress concentration on a specific part. A groove-shaped receiving portion 54 that protrudes from the front to the upright portion 22a of the rear link 22 projects from the left and right outer ends of the lumbar pad 15.

  As shown in FIG. 8 (B), a chevron-shaped stopper projection 55 is formed on the inner bottom surface of the receiving portion 54, while a recessed portion 56 into which the stopper projection fits is formed in multiple stages on the standing portion 22a of the rear link 22. Forming. The lumbar pad 15 is pushed against the upright portion 22a of the rear link 22 by the tension of the support sheet 14, and therefore the lumbar pad 15 is held so that it cannot be displaced downward even if the recess 56 is very shallow.

  Further, on the back surface of the lumbar pad 15, as an example of the operation unit, a lateral operation piece 57 that can be picked by a person with a finger is integrally formed. Therefore, the user of the chair can adjust the height position of the lumbar support 14 according to his / her preference, physique, etc. (the operation piece 57 can be operated behind while sitting). As shown in FIGS. 7 and 8, an inward restricting claw 58 is formed at the lower end and the rear end of one plate constituting the receiving portion 54, while the standing piece 22 a in the rear link 22 has The notch part 59 in which the restricting claw 58 can move up and down is formed.

  The vertical movement range of the lumbar pad 15 is restricted by restricting the vertical movement range of the restricting claw 58 by the notch 59, and the lumbar pad 15 is held so as not to drop. Therefore, the notch 59 and the restricting claw 58 function as the stroke restricting means and the fall preventing means of the lumbar pad 15. A spacer 60 that stably holds the receiving portion 63 when the lumbar pad 15 is retracted is disposed on the inner surface of the upper inside cover 39.

  Now, as clearly shown in FIG. 11, the lumbar pad 15 is arranged so as to partially overlap the back column 10 in a front view, and therefore the lumbar pad 15 is arranged near the left and right ends of the backrest 5. Yes. Therefore, the lumbar pad 15 does not stand out greatly and is excellent in aesthetics. In particular, since the lumbar pad 15 is not conspicuous in the back view of the chair and the support sheet 14 is emphasized, it has a simple appearance. In addition, since the front surface of the back frame 13 is inclined so as to be shifted backward as it goes to the left and right inward, the support sheet is allowed to extend backward and deform due to leaning on a person, and to the support sheet 14 The burden is also reduced.

  Also, the lumbar pad 15 is curved in a side view and a plan view (particularly the curvature in the side view is important), and the lumbar pad 15 is long in the vertical direction and has a large front area. Since the strong force does not concentrate on the narrow portion of the sheet 14, the support sheet 14 can ensure high durability. In addition, the lumbar pad 15 has a vertically elongated shape with a vertical length of about three times the maximum width, but the outer end surface 15a is nearly vertical in front view, whereas the inner end surface is outwardly convex. It has a shape that is loosely bent into a strip and has a rounded odor in front view.

  With such a shape, an appropriate support function is exhibited following the shape of the support sheet 14. In other words, the degree of curvature of the support sheet 14 in plan view increases as it goes down due to the action of the rear link 22 of the back frame 13, but the lumbar pad 15 has roundness in front view as in the embodiment. In other words, it becomes easier for the support sheet 14 to bend backward, so that the support sheet 14 fits into the three-dimensional bending form of the support sheet 14.

(5). Second Embodiment FIG. 12 shows a second embodiment. This embodiment is also basically the same as the first embodiment. As a difference from the first embodiment, first, the lower member 13c of the back frame 13 is a separate member from the side member 13a. It is done. In this embodiment, the lumbar pad 15 is formed in a plate shape, and a long flexible sheet 62 is arranged between the lumbar pad 15 and a support sheet (not shown). The flexible sheet 62 is fixed to the side member 13 a with screws or the like, but may be moved up and down together with the lumbar pad 15.

(6). Others The present invention can be embodied in various ways other than the above embodiment. For example, the application target is not necessarily limited to a rotating chair, and can be applied to a fixed chair such as a theater chair or a bench. The backrest is preferably a support seat system, but does not exclude the system having an inner shell and a cushion. Needless to say, the lumbar pad 15 does not need to be retracted when locked, and therefore, the lumbar pad can be attached to the side member of the back frame so as to be movable up and down. For example, the lumbar pad may be formed in a block shape so that a person can handle it.

DESCRIPTION OF SYMBOLS 1 Leg apparatus 3 Base 4 Seat 5 Backrest 8 Swing frame 10 Back column of rocking frame 13 Back frame 13a Side member of back frame 14 Support sheet 14a Lumber support part 15 Lumber pad 54 Receiving part 57 Operation as an example of operation part Fragment

Claims (1)

It has a seat and a backrest, and the backrest has a lumbar support portion that hits the waist of a seated person, and supports the lumbar support portion of the backrest with a pressing means whose height can be adjusted from behind. ,
A chair called
The pressing means is separated into two lumbar pads arranged on the left and right sides across the middle part of the backrest, and the left and right lumbar pads are provided with an operation unit for a person to move up and down.
Chair with backrest.