KR20090124049A - Structure of backplate for chair - Google Patents

Abstract

PURPOSE: A structure of the back of a chair is provided, which supports a seat occupant comfortably, keeps a correct seating posture, and reduces inconvenient feeling in case of taking a seat for a long time. CONSTITUTION: A structure of the back of a chair is equipped with the back of a chair(10) which is mounted while being divided into the right and left to support the pelvis and the back of a user from different positions. Each back of a chair comprises a back seat consisting of cushion material and a back panel in which the back seat is integrally attached. A site projected to the front is formed into the waist support projection(10c). The top part(10a) of the back of a chair supports the shoulder of a seat occupant. The bottom part(10b) of the back of a chair supports the lumbar vertebra of the seat occupant.

Description

Structure of backplate for chair

The present invention relates to a chair back structure, and more particularly, by providing a back structure that can suitably support the pelvis and lumbar region of a seated person in a chair having two left and right backrests, thereby supporting the seated person comfortably and comfortably. The present invention relates to a chair back structure capable of keeping a correct posture by squeezing appropriately for a seated person's body shape.

As is well known, a conventional chair is composed of a leg part, a seat plate part and a backrest, and the leg part is provided at the lower part of the chair to support the seat plate part and the backrest provided at the upper part and to prevent the chair from falling when seated. Has

The upper end of the leg is provided with a seat plate that is mechanically connected to seat the seat of the seat occupant, and the back plate is provided with a backrest supporting the back of the seat.

In addition, the seat plate portion is optionally provided with an armrest portion for supporting the arm of the seat, the height adjuster for adjusting the height of the seat plate according to the physical condition of the seat is provided mechanically connected to the lower surface of the seat plate.

At this time, the backrest has been developed to more comfortably support the back of the seated person when sitting and to effectively remove the load on the spine, the chair backrest having a dual back structure consisting of a pair of left and right is divided in the longitudinal direction recently Applied.

In particular, in addition to the chair as a means of simply sitting in the roots, based on the ergonomic design, the shape of the seat can be manufactured in a waveform according to the shape of the user's hip, or the back and body of the body can be changed by changing the structure and shape of the backrest. Several techniques have been proposed, such as support for comfort.

As described above, since the overall structure of the chair affects the posture of the seated person and the body according to the posture, the structure of the chair according to the correct posture of the seated person and the ergonomic design is required, and the chair is more preferable. The correct posture should be maintained by the structure so that the structure can properly support the body of the seated person.

In fact, even if it is composed of a chair structure with good conditions and environment, if the seated person is sitting in a bad position, the development of children and adolescents during the growing season may not be able to supply the lower body with a cause for promoting the deformity of the spine, It is known to increase the risk of physical disorders such as spinal malformation, low back pain, and fatigue accumulation.

Therefore, the chair is simply ergonomic and supports the seated person comfortably and comfortably at the same time, while keeping the correct posture by holding the seat properly according to the body of the seated person to prevent spinal malformation and low back pain and fatigue. It would be desirable to have no volumetric abnormalities.

As mentioned above, the spine, which is the center of the body, recognizes that the structure of the chair and the seating posture are inseparable from each other, and the efforts and studies to satisfy various needs of customers by maintaining the correct posture of many products Development is being done.

Many of them have been filed in Korea and have a characteristic configuration, Republic of Korea Patent No.156492 (registered on July 2, 1998. Spine protection spring chair), Republic of Korea Utility Model Registration No. 20-0179560 (registered on February 2, 2000, chair backrest with a pressurizing means), Republic of Korea Utility Model Registration No. 20-0211495 (registered on November 13, 2000, chair back structure ), Republic of Korea Utility Model Registration No. 20-0245168 (2001.8.22. Registration, chair backrest provided with a waist support means) and the like have been proposed and known, respectively.

As described above, the chairs are known to suggest more convenient and comfortable chairs by structural changes to the corresponding parts.

Accordingly, the present applicant proposes a new type of chair that can be used to fit the structure of the human body as a means of simply sitting in accordance with this trend, as well as to fit the structure of the human body, and to maintain the sitting posture more comfortably without overly burdening the upper body. It came to.

That is, the present invention was invented in accordance with the need of a new type of chair that can maintain a more comfortable sitting posture without straining the upper body, the object of the present invention is the seat of the pelvis and By providing a backrest structure that can support the lumbar region appropriately, it is to provide a chair backrest structure to support the seated person comfortably and comfortably, and at the same time to brace the body of the seated person to maintain a correct posture.

In particular, according to the present invention, the seat line of the backrest itself is manufactured in accordance with the seat (hip) line of the seated person so that the hip (hip) itself goes deep into the chair at the time of seating and the hips are in close contact with the seat line of the chair. Another object of the present invention is to provide a chair back structure so as to touch a large area and to receive pressure uniformly, thereby reducing uncomfortable seating feeling during long time sitting.

As such, the present invention is to provide a chair back structure that can provide a more comfortable and comfortable when seated for a long time, as well as a low incidence of body fatigue to meet various needs of customers and improve the productability and reliability of the product. .

The present invention for achieving the above object is a seat plate seat as a seating seat, seat back for supporting the back of the user, back support plate for supporting the backrest from the back, and fixing the backrest to the backrest plate In the structure of the chair comprising an elastic coupling member and the leg portion supporting the seat plate, the backrest and the backrest plate with respect to the ground, the backrest may be supported side by side at different positions from the back of the seater to the pelvis. Mounted separately; Each of the backrest is composed of a backsheet made of cushioning material and a back plate to which the backsheet is integrally attached, and when viewed from the side, a part of 3/5 from the top of the backrest is bent in a chevron shape of "<" shape. The bent and protruding portion is formed as a lumbar support, and the upper back portion of the upper back portion supports the shoulder of the seat occupant's waist, and the lower portion of the lower back portion of the lumbar support portion receives the lumbar spine behind the occupant's hip. A chair back structure is provided which has a structure to be hit.

” 형태의 구조로 형성됨과 아울러 전면에 탄성지지대결합구가 마련되어 상기 탄성지지대에 등받이받침판의 탄성지지대결합구를 끼워서 체결한 상태에서 등받이받침판 후방에서 고정볼트로 조여서 고정함으로써, 상기 등받이받침판이 좌판부 후방에 수직하게 설치됨과 동시에 착탈 가능하게 체결 고정되는 것을 특징으로 한다.Here, the rear side of the seat plate portion is provided with an elastic support provided to project upwardly toward the rear of the sieve seat plate fastened to the bottom surface side of the seat plate portion, the backrest plate corresponding to the shape structure of the backrest to elastically support the rear of the backrest “

The support plate is formed in the form of a ”form and is provided with an elastic support coupler on the front side by fastening with a fixing bolt at the back of the back support plate while the elastic support coupler of the back support plate is fastened to the elastic support. It is installed vertically at the back and at the same time characterized in that the fastening detachable.

In addition, according to a preferred embodiment of the present invention, the elastic coupling member is divided into a first elastic coupling member and a second elastic coupling member has a structure that is fastened to elastically support the upper end and the lower end of the backrest, respectively.

At this time, the first elastic coupling member has a structure including a corrugated pipe having a nut inserted therein, which is fastened to the back plate of the backrest, and a first adjusting bolt which is fastened and fixed to the nut inside the corrugated pipe by passing through the backrest plate. Have

The second elastic coupling member includes a corrugated pipe having a nut inserted therein, which is fastened to the back plate of the backrest, a spring that imparts tension through the corrugated pipe and the backrest plate, and passes through the backrest plate and the spring. And a second adjusting bolt formed integrally with a screw part and a smooth body part which are fastened to the nut so as to be fastened to the nut, and are disposed between the lower part of the backrest and the backrest plate and fastened, thereby allowing the seated part of the seat back to be seated. As the load according to the sitting position is applied, the smooth body portion of the second adjustment bolt with the tension action of the spring is characterized in that it is to adjust the tension interval while moving between the backrest plate.

According to the present invention, by providing a backrest structure that can properly support the pelvis and lumbar region of the seated person in a chair having two left and right backrests, it supports the seated person comfortably and comfortably, and at the same time, it is pressed against the body shape of the seated person. It can keep the effect.

In particular, according to the present invention, the seat line of the backrest itself is manufactured to fit the hip line of the seated person so that the hips themselves enter deep into the chair at the time of seating, and the hips are in close contact with the seat line of the chair. By contacting a large area and receiving pressure uniformly, there is an effect that can reduce the uncomfortable seating feeling when sitting for a long time.

As described above, the present invention is more comfortable and comfortable when sitting for a long time, as well as low incidence of fatigue of the body to satisfy the various needs of customers and has the effect of improving the productability and reliability for the product.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

1 is a perspective view showing a chair with a backrest according to the present invention, Figure 2 is a side exploded perspective view showing a chair with a backrest according to the present invention, Figure 3 is a perspective view showing the main structure of the backrest according to the present invention 4 is a cross-sectional view of the portion A of FIG. 2 showing the structure of the first elastic coupling member used to fasten the upper end of the chair back according to the present invention, Figure 5 is fastening the lower end of the chair back according to the invention 2 is a cross-sectional view of the portion B of Figure 2 showing the structure of the second elastic coupling member used for.

1 and 2, a chair to which the chair back 10 is applied according to a preferred embodiment of the present invention has a seat plate 20 as a seating seat and armrests provided at both sides of the seat plate 20. The seat 50, the backrest 10 for supporting the user's back, the backrest plate 30 for supporting the elastic coupling member 70 from the back of the backrest 10, and the chair as a whole to the ground It has a leg 40 supporting it.

The seat plate portion 20 is formed of a cloth material containing a cushion material therein. However, if necessary, it may be made of plateless plastic or steel plate.

Referring to the drawings, the upper surface of the seat plate portion 20 has a wave shape that is constantly curved to fit the shape of the user's hip, so that the user can sit more comfortably.

The armrest part 50 is disposed on both sides of the seat plate part 20 to support both arms of the user.

The armrest portion 50 can be configured to adjust the height of the seat plate portion 20 as needed.

Of course, the spirit of the present invention can be applied to a chair (not shown) in which the armrest part 50 is not formed.

And, the upper end of the backrest plate 30, the headrest 60 for supporting the head of the seated seat may be detachably formed on the headrest coupling port 61 by the fixing bolt 90.

In addition, the headrest coupler 61 is fastened and fixed to the backrest plate 30 by the fixing bolt 91, the fastening height of the headrest coupler 61 is adjustable.

In particular, although not shown in detail, the hanger 62 to hang the clothes on the headrest coupling port 61 may be provided integrally or detachably.

The back support plate 30 is disposed at the rear of the plurality of backrests 10 in a state in which the backrest plate 30 is vertically coupled to the rear of the seat plate part 20 by an elastic support coupler 31 fitted to the elastic support 80 and fixed bolts. As it is fixed by the (92) serves to support the backrest 10 from the rear.

The backrest plate 30 is manufactured not only to have a certain thickness, but also to be broken or bent by a user's leaning force.

For reference, in the case of a conventional general chair (not shown), the part serving as the backrest plate 30 simply took a plate shape or had a small area.

However, if the backrest plate 30 has a simple plate shape as described above, the more the user leans on the backrest 10, the higher the backrest plate 30 is likely to be bent, and accordingly the backrest plate 30 is There may be a problem that the backrest 10 does not properly support the backrest 10 may not perform its function.

”자 형태로 중앙 부근에서 상하단이 약간 꺾여진 구조를 가지도록 설계되어 있다.Thus, in the present embodiment, when viewed from the side, as shown in Figure 2 and 3, the backrest plate 30 is approximately "

It is designed to have a structure in which the upper and lower ends are slightly bent near the center.

”자 형태의 구조로 등받이받침판(30)이 형성되고, 이를 통해서 등받이(10)를 지지하도록 함으로써, 사용자가 등받이(10)에 기대는 힘이 가중된다 하더라도 등받이받침판(30)에서 충분한 하중 분산이 이루어지면서 탄성 복원력을 발휘하게 됨에 따라 등받이(10)가 제 기능을 수행하기에 충분하도록 설계하고 있다.As such, the invention is approximately “

The backrest plate 30 is formed in the shape of a ”shape, and thereby supports the backrest 10 so that a sufficient load distribution in the backrest plate 30 is achieved even if the user leans against the backrest 10. As the elastic restoring force is exerted, the backrest 10 is designed to be sufficient to perform its function.

Of course, in order to faithfully perform the original function of supporting the backrest 10 in addition to these morphological features it will be preferable that the backrest plate 30 itself is made of a material having a certain elasticity.

In addition, the shape characteristics of the backrest plate 30 is designed to correspond to the shape structure of the entire backrest 10, thereby contributing to improve the appearance of the chair.

When the backrest plate 30 supports the two backrests 10 from the rear, the two backrests 10 should be fixed to the backrest plate 30, respectively, as described above. With respect to 30, each of the two backrests 10 needs to be elastically approached and spaced apart.

This is enough for all users of different sizes or weights.

To this end, the backrest plate 30 and the two backrest 10 corresponding thereto are respectively fixed to the backrest plate 30 to the backrest plate 30 and each of them is elastically distance-controlled so that the elasticity can be adjusted. A plurality of first and second elastic coupling members 71 and 72 may be further provided.

The first and second elastic coupling members 71 and 72 will be described later.

As described above, the present invention is characterized in that the shape structure of the backrest 10 and the organic arrangement structure of the backrest support plate 30 and the plurality of first and second elastic coupling members 71 and 72 supporting the same are described above. As described above, the backrest 10 according to the present invention is disposed to extend upward from the rear of the seat plate portion 20 to support the user's back.

That is, the present invention is seated at the back plate 10 in the right posture in the user sitting deep in the seat plate 20, the user's pelvis and lumbar spine is comfortably supported and seated at the same time as the back of the backrest 10 Even when the body leans forward, the pelvis and lower back are elastically supported by the backrest 10 so that the backrest 10 suitably supports the user's posture change, thereby taking a more comfortable sitting posture. Its characteristics are to make it possible.

The backrest 10 is composed of two left and right sides as in a chair (not shown) having a conventional dual bag structure.

Here, the backrest 10 according to the present invention is composed of a back seat 12 made of a cushion material and the back plate 12 to which the back seat 11 is integrally attached.

At this time, the back plate 12 is in the form of "<", the upper bottom portion (10a, 10b) is a seagull shape relative to the waist support protrusion (10c) slightly protruded forward from the bottom just below the center of the entire length of the backrest 10 It has a structure bent by.

In addition, the back seat 12 of the structure is integrally mounted to the back seat 11 of the cushion material having a predetermined thickness, so that when the user leans on the backrest 10 to support the back with a cushion feeling to provide comfort and comfort Will be.

That is, the backrest 10 composed of the back plate 12 and the backsheet 11 has a top portion 10a of the user's back from both sides of the shoulder, based on the central portion of the protruding backrest 10c. The lower left and right sides 10b support the part extending from the center of the back of the user to the waist.

In particular, the backrest 10 has a shape structure that fits the vertebral flexion of the user's pelvis to the waist, and the waist to the shoulder in two stages sitting on the seat plate 20, thereby supporting the user's comfort cushioning Will be

The backrest structure according to the present invention will be described in more detail.

Each of the backrests 10 of the present invention has a straight line in the horizontal direction in the horizontal direction in view of the overall structure so that both backrests can support the inner back portion of the backrest when viewed in the axial direction perpendicular to the seat plate portion 20. 3/5 to 2 of the backrest 10 in the length (bottom) direction so as to be bent from the outside (left and right ends) to the shape of the needle (b) and to support the back to the inner bottom of the back of the back 10. The upper portion 10a, which is / 3, is formed in a straight line (not convex) (see Figs. 2 and 3), and the lower portion 10b, which is 2/5 to 1/3 of the backrest 10, is also straight (not convex). (See Figs. 2 and 3).

In addition, the needle-shaped (b) shape of the outer side (left and right ends) when viewed in the horizontal direction of the horizontal axis disposed on the seat plate portion 20 has a needle-shaped shape on the upper back 10 and a needle-shaped chair under the back 10. In the same way as the chair backrest plate 30 in the center of the shape to be uniformly inclined to form a waist support protrusion (10c), the lower back portion 10b of the bent back (10) supports the lumbar spine behind the hip, the upper end portion (10a) Is to support the shoulders above the waist of the person.

Since the inner bottom of the backrest 10 and the left and right outer sides are formed in a straight line in the shape of the lower end of the needle (b), the center of each of the backrests 10 is not formed as a concave portion as viewed vertically. As seen from the center is formed of a belt-shaped backrest 10c rather than a convex portion of the contact surface of the horse's bowel, the backrest 10 is wrapped around the waist to add comfort.

Each of the backrests 10 may be properly adjusted in tension by the first and second elastic coupling members 71 and 72 to be described later.

That is, the standing state or inclined state with respect to the seat plate 20 can be easily adjusted by the plurality of first and second elastic coupling members 71 and 72, so that the body size or It is intended for use by users of different weights.

Here, the structure and operation of the first and second elastic coupling members 71 and 72 will be briefly described with reference to FIGS. 4 and 5.

In this case, the plurality of first and second elastic coupling members 71 and 72 are basically mediated between the backrest 10 and the backrest plate 30 so that the backrest 10 is elastically supported and fixed to the backrest plate 30. It serves to make, but the structure and operation are different.

First, as shown in FIG. 4, the first elastic coupling member 71 serves to fasten and support the upper end portion 10a of the backrest 10, and the rear plate of the backrest 10 ( 12, the first adjustment bolt that is fastened and fixed to the nut 71c in the corrugated pipe 71a by passing through the corrugated pipe 71a having the nut 71c inserted therein and the backrest plate 30. 71b).

Although not shown, the end of the first adjustment bolt (71b) exposed to the outside of the backrest plate 30 is preferably provided with a knob-shaped head that can be turned by the user, the head of the first adjustment bolt (71b) It is also possible to operate by using a separate tool such as a screwdriver formed in the form of a screw groove in the site.

Here, the first adjustment bolt 71b has a structure in which a thread is formed in the entire bolt so as to pass through the backrest plate 30 to be coupled to the nut 71c, and the end of the first adjustment bolt 71b has a backrest plate. By being exposed to the rear of the 30, as the first adjustment bolt (71b) is rotated in the forward and reverse direction, the sieve fastening is maintained as much as the corrugated pipe (71a) distance between the backrest plate 30 and the backrest (10). .

At this time, the upper part of the backrest fastened and fixed to the backrest plate 30 by the first elastic coupling member 71 when the seated person exerts a sieve load on the back, the backrest 10 is tensioned backwards and is repelled by force The balance is maintained, and if no load is applied, the original state is restored.

On the other hand, the second elastic coupling member 72, as shown in Figure 5, serves to fasten and support the lower end 10b of the backrest 10, the back plate (10) of the backrest (10) 12, a corrugated pipe 72a having a nut 72c inserted therein, a spring 72d for providing a tension between the corrugated pipe 72a and the backrest plate 30, and the backrest plate ( 30) and a structure including an adjusting bolt 72b integrally formed with a threaded portion 72e and a smooth body portion 72f which are fastened to the nut 72c so as to be fastened to the nut 72c through the spring 72d. Have

Here, the second adjustment bolt 72b is formed integrally with the threaded portion 72e and the threaded portion 72e through the backrest plate 30 and coupled to the nut 72c to the rear surface of the backrest plate 30. Exposed to rotate the screw portion (72e) in the forward and reverse direction is provided with a smooth body portion (72f) for adjusting the separation distance between the backrest plate 30 and the backrest (10).

At this time, the end portion of the second adjustment bolt 72b exposed to the outside of the backrest plate 30 is preferably provided with a knob-shaped head portion 72g that the user can hold and turn, the second adjustment bolt 72b It is also possible to operate by using a separate tool such as a screwdriver to form a screw groove in the head portion of the.

Due to the structure of the second elastic coupling member 72 when the load according to the seated position of the seated on the lower end portion 10b of the backrest 10, the tensioning action of the spring (72d) and the second adjustment The smooth body portion 72f of the bolt 72b variably moves the backrest plate 30 to adjust the tension interval.

That is, the hips (hip) itself deep into the chair when seated, the hips will be in close contact with the back seat 11 line of the lower portion (10a) of the chair back (10), in particular, the seated person sitting forward In this case, the butt line in close contact with the backsheet 11 line of the lower portion 10a of the backrest 10 abuts on a larger area and is uniformly pressured, thereby providing the second elastic coupling member 72. At the same time as the tension action occurs in the spring 72d of the), the body portion 72f, in which the threaded portion 72e of the second adjustment bolt 72b is fixed to the nut 72c, is pushed toward the back of the backrest plate 30. As it exits, an appropriate tensioning action occurs in accordance with the balance of forces acting on the backrest 10.

Therefore, it is possible to reduce the uncomfortable seating feeling even when sitting for a long time through the tension action as described above.

In addition, the left and right backrest 10 is moved to fit the body structure of the seated person, thereby providing comfort and comfort to the seated person and protecting the spine.

As such, according to the present embodiment, not only can be used according to the structure of the human body, but also does not put a strain on the upper body to maintain a more comfortable sitting posture, convenient to assemble and disassemble by parts, excellent strength and durability There is an effect that can be enhanced.

As described above, the present invention is not limited to the described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the present invention, which will be apparent to those skilled in the art.

Therefore, such modifications or variations will have to be belong to the claims of the present invention.

1 is a perspective view illustrating a chair to which a chair back is applied according to the present invention;

Figure 2 is a side exploded perspective view showing a chair with a chair back applied in accordance with the present invention,

Figure 3 is a perspective view of the main part showing a chair back structure according to the present invention.

Figure 4 is a cross-sectional view of the portion A of Figure 2 showing the structure of the first elastic coupling member used to fasten the upper end of the chair back according to the invention,

5 is a cross-sectional view of the portion B of Figure 2 showing the structure of the second elastic coupling member used to fasten the lower end of the chair back according to the present invention.

* Explanation of symbols for the main parts of the drawings *

10: backrest 10a: upper part

10b: lower portion 10c: lumbar support

11: back sheet 12: back plate

20: seat plate portion 30: backrest plate

31: elastic support coupler 40: leg portion

50: armrest 60: headrest

70: elastic coupling member 71, 72: first, second elastic coupling member

71a, 72a: Corrugated pipe 71b, 72b: 1st, 2nd adjustment bolt

71c, 72c: Nut 72d: Spring

72e: thread portion 72f: body portion

80: elastic support 90,91,92: fixing bolt

Claims (3)

Seat plate portion 20 as a seated seat, a backrest 10 supporting the back of the seater, a backrest plate 30 supporting the backrest 10 from the back, and a backrest plate of the backrest 10 And a leg portion 40 supporting the seat plate 20, the backrest 10 and the backrest plate 30 with respect to the ground. In structure, The backrest 10 is mounted separately from the left and right two so as to support side by side at different positions from the back of the seated person to the pelvis; Each backrest 10 is composed of a backsheet 11 made of cushioning material and a back plate 12 to which the backsheet 11 is integrally attached. The portion of / 5 to 2/3 is bent in a chevron shape of "<" shape, and the portion which is bent and protruded forward is formed by the lumbar support 10c, and the upper back of the lumbar support 10c ( 10) the upper end portion 10a supports the shoulders of the seat occupant's waist, and the lower back 10 of the lower backrest 10c has a structure that supports the lumbar spine behind the seat's hips. Chair back frame made. The method of claim 1, The rear side of the seat plate 20 is provided with an elastic support 80 is installed to protrude upward toward the back of the sieve seat plate 20 fastened to the bottom surface side of the seat plate 20, The backrest plate 30 corresponds to the shape structure of the backrest 10 to elastically support the back of the backrests 10.

In addition, the backrest plate 30 is formed in a state in which the elastic support coupler 31 is provided on the front surface and the elastic support coupler 31 of the backrest plate 30 is fitted to the elastic support 80. By fastening with a fixing bolt 92 at the rear, The backrest plate 30 is a chair back structure, characterized in that is installed vertically at the back of the seat plate portion 20 and is detachably fastened. The method according to claim 1 or 2, The elastic coupling member 70 is divided into a first elastic coupling member 71 and the second elastic coupling member 72 is fastened to elastically support the upper end 10a and the lower end 10b of the backrest 10, respectively; The first elastic coupling member 71 passes through a corrugated pipe 71a having a nut 71c inserted therein and fastened to the back plate 12 of the backrest 10, and passes through the backrest plate 30. Has a structure including a first control bolt (71b) that is fastened and fixed to the nut (71c) inside the corrugated pipe (71a), is disposed between the upper end portion 10a of the backrest 10 and the backrest plate 30 fixed and fastened Become; The second elastic coupling member 72 is a corrugated pipe 72a having a nut 72c inserted therein and fastened to the rear plate 12 of the backrest 10, and the corrugated pipe 72a and the backrest plate 30. Spring 72d for tensioning and passing through the backrest plate; and a threaded portion 72e fastened to the nut 72c so as to pass through the backrest plate 30 and the spring 72d and engage with the nut 72c. The smooth body portion (72f) has a structure comprising a second control bolt (72b) formed integrally, and is disposed between the lower end portion 10b and the backrest plate 30 of the backrest 10, the backrest ( As the load according to the seated position of the seated person acts on the lower end portion 10b of 10), the smooth body portion 72f of the second adjustment bolt 72b is supported by the tensioning action of the spring 72d. Chair back structure, characterized in that to adjust the tension gap while moving between.

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