JP7121577B2 - Chair - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chair in which a backrest is connected to left and right backrests so as to be tiltable backward.

Chairs in which the back rests against spring means are widely used. In this case, there are cases where the backrest is attached to a rearwardly tiltable back support, and there are cases where the backrest is connected to a fixed back support so that it can be tilted backwards. A simple chair, such as a conference room chair, has the backrest connected to the back support so that it can be tilted backwards as in the latter case.

The backrest is designed to tilt backwards against the spring means, and even if the backrest is connected to the back support so that it can tilt backwards, it is necessary to arrange the spring means at the connecting portion. Therefore, in Patent Document 1, a reinforcing plate is fixed to the back surface of the backrest, bearing portions protruding outside the left and right side surfaces of the backrest are provided at both left and right ends of the reinforcing plate, and spring means are arranged inside the bearing portions. is disclosed.

On the other hand, Patent Document 2 discloses that the upper end of the back support is formed into a horizontal support shaft and connected to the back surface of the backrest with a bracket, and the bracket and spring are covered with a back plate. Since the support shaft and the bracket protrude behind the backrest, bulging portions covering the brackets are formed on both left and right sides of the back plate.

JP 2006-204732 A CD-ROM of Japanese Utility Model No. 4-133756

In Patent Literature 1, the bearings protrude greatly on the left and right outer sides of the backrest, so there is a problem of lack of compactness. In addition, since the reinforcing plate protrudes in a convex shape from the back surface of the backrest, the reinforcing plate is conspicuous and does not necessarily have a good appearance.

On the other hand, in Patent Document 2, since the back support can be brought close to the side surface of the backrest, it is more compact and looks better than in Patent Document 1. , it can be said that it is difficult to sufficiently meet the demand to make the back of the backrest neat.

The present invention has been made to improve such a situation, and it is an object of the present invention to enable a backrest to be connected to a backrest so that it can be tilted backward while ensuring a compact and neat appearance. be.

The present invention includes various configurations, typical examples of which are specified in each claim. Of these, the invention of claim 1 is
"Comprising a seat, a backrest , and left and right backrests arranged closely or close to the sides of the backrest ,
The backrest has a back inner shell made of synthetic resin and a back cushion arranged in front thereof, and the back inner shell has a large number of forward facing concave portions surrounded by a group of longitudinally elongated ribs and a group of horizontally elongated ribs. A desired thickness is ensured by providing a group of places,
and the backrest is connected to the back support so as to tilt backward against the spring means when the seated person leans back,
lateral recesses that are open toward the back support are formed in left and right side portions of the back inner shell, and the spring means are arranged in the lateral recesses;
In addition, the portion of the back inner shell provided with the lateral recess does not have the forward facing recess, and the portion of the back inner shell provided with the lateral recess does not protrude backward.
It is configured.

The invention of claim 2 is, in claim 1,
"In the lateral recess of the backrest, a movable bracket fixed to the lateral recess and a fixed bracket fixed to the back support are arranged, and the spring between the movable bracket and the fixed bracket is arranged. We are arranging the means
It is configured.

The invention of claim 3 is
" Comprising a seat, a backrest, and left and right back supports arranged closely or close to the sides of the backrest,
The backrest is connected to the back support so as to tilt backward against the spring means when the seated person leans back,
A configuration in which the backrest is formed with a lateral recess that opens toward the back support, and the spring means is disposed in the lateral recess,
A movable bracket fixed to the lateral recess of the backrest and a fixed bracket fixed to the back support are arranged in the lateral recess of the backrest, and the spring means is arranged between the movable bracket and the fixed bracket. is placed,
Further, a pivot pin having an exposed portion that enters the spine is fixed to the fixed bracket,
A bearing groove is formed in the back support so that the exposed portion of the pivot pin can be dropped from the front,
Further, the fixing bracket is fixed to the back strut by a bolt arranged below the pivot pin, and the bolt is inserted from the outer surface of the back strut."
It is configured.

The invention of claim 4 is, in claim 3,
"The movable bracket has a substantially cylindrical shape having a front plate, a rear plate, and inner and outer plates, and the pivot pins are fixed through the side plates,
The fixed bracket has a rear plate and left and right side plates, and is arranged inside the movable bracket. An outer plate of the movable bracket is formed with a relief hole through which the bolt penetrates. The hole is elongated to allow the movable bracket to rotate."
It is configured.

According to the invention of claim 5, in any one of claims 2 to 4,
``The movable bracket and the fixed bracket are made of metal, and the movable bracket is provided with a synthetic resin side bracket that is in close contact with the side surface of the back column.''
It is configured.

According to the invention of claim 6, in any one of claims 2 to 4,
"The backrest has a structure in which a back cushion is stretched on a back inner shell made of synthetic resin, and a metal reinforcing plate is arranged on the back surface of the back inner shell, extending continuously to the left and right ends thereof, and the reinforcement The plate is fitted into a groove formed in the back inner shell,
Further, the reinforcing plate, the back inner shell and the movable bracket are fastened together with screws, and the reinforcing plate is covered with a skin material.
It is configured.

In the invention of the present application, since the spring means is built in the thick portion of the backrest, the backrest is prevented or suppressed from forming a protrusion while maintaining a compact structure in which the back support is arranged close to the side surface of the backrest. can be tilted backward. Therefore, it is possible to give the chair a high commercial value by allowing the backrest to retain a rocking function while maintaining a neat appearance as if the backrest does not tilt backward.

The structure of the backrest varies, but most of the cushion-type seats have a structure in which a back cushion is attached to a back inner shell (back plate) made of synthetic resin. In addition, since synthetic resin is weaker than metal, for example, if a synthetic resin back inner shell is directly connected to the back support with a pivot pin, a large load is applied to the narrow portion of the back inner shell, resulting in poor strength. anxiety may arise.

On the other hand, if a movable bracket and a fixed bracket are provided as in claim 2, both are made of high-strength members such as metal. The locking function of the backrest can be secured. Therefore, the freedom of choice for the material and structure of the backrest is increased, and the reality is excellent.

As a means for connecting the back support and the backrest, there are two possible ways to fix a pivot pin to the back support and to fix a pivot pin to the backrest. When the pivot pins are fixed to the backrest as in the latter case, the pivot pins can be firmly fixed to the backrest in advance, which has the advantage of excellent support stability of the backrest, but the pivot pins project outside the backrest. Since there is an exposed portion, when assembling the chair, it is necessary to insert the back support into the pivot pin. Therefore, there is a problem of poor workability in assembling the chair.

On the other hand, when the configuration of claim 3 is adopted, the exposed portion of the pivot pin is dropped into the bearing groove, so that the backrest can be attached after the back support is assembled in a predetermined state. Therefore, workability in assembling the chair is good. Moreover, since the fixing bracket is fixed to the back support with bolts, the pivot pin does not move upward, so there is no problem that the backrest comes off the back support even though it is a drop-in type. . Therefore, the chair can be efficiently assembled while ensuring the locking function of the backrest.

Various forms can be adopted for the movable bracket and the fixed bracket, but when the structure of claim 4 is adopted, the movable bracket is cylindrical and the fixed bracket is grooved, so that high strength can be secured and the chair can be mounted. can ensure sufficient strength.

As mentioned above, by making the movable bracket and the fixed bracket made of metal, high strength can be ensured, but when the metal movable bracket and the back support rub against each other, an abnormal noise is generated and the user feels uncomfortable. concerned about having

On the other hand, if a resin side bracket is employed as in claim 5, the occurrence of rubbing noise can be prevented and a comfortable rocking state can be realized.

In the structure of claim 6, since the reinforcement plate can prevent a large load from being applied to the narrow portion of the back inner shell, the back inner shell can be made as thin as possible to improve the appearance, while ensuring necessary strength. . Therefore, the commercial value of the chair can be improved. In addition, since the reinforcing plate is fitted into the groove formed in the back inner shell, the upper and lower side edges of the reinforcing plate are prevented from being stepped with the back inner shell, thereby improving the appearance. .

In the external view of the embodiment, (A) is a perspective view with armrests, (B) is a perspective view with no armrests, (C) is a rear perspective view, and (D) is a seat. FIG. 4 is a perspective view in a separated state; (A) is a plan view, (B) is a side view, (C) is a front view, and (D) is a rear view. (A) is a partially broken perspective view of the backrest, (B) is a partially broken perspective view of the backrest with the skin material removed, and (C) is a partially separated side view of the backrest. It is a figure which shows the rotation support means of a backrest, (A) is the isolation|separation perspective view seen from the front, (B) is the isolation|separation perspective view of a spring unit. (A) is an isolated perspective view showing the pivotal support means of the backrest, (B) and (C) are isolated perspective views showing the relationship between the back support and the cover. (A) is a longitudinal side view seen from the VI-VI direction of FIG. 7(B), and (B) and (C) are perspective views of the back tilting unit. (A) is a partial front view with the back cushion displayed, and (B) is a partial front view with the back cushion omitted.

(1). Overview Next, embodiments of the present invention will be described. The present invention is applied to a swivel chair used in an office or the like. First, with reference to FIGS. 1 and 2, the outline of the chair will be explained. The chair has a seat 1, a backrest 2 and a leg device 3. The leg device 3 has five branch rods and a leg strut 4 composed of a gas cylinder. Casters are provided at the ends of each branch rod, and a base (not shown) is attached to the upper end of the leg strut 4. It's stuck. The leg support 4 is arranged slightly behind the front-back midpoint of the seat 1. - 特許庁

Although not shown, the base is in the form of a rectangular block (horizontally long rectangle) in plan view, and left and right front frames (seat posts) 6 and left and right back posts (rear frames) 7 are fixed to the base. A seat 1 is attached to a front frame 6 so as to be tiltable forward and backward, and a backrest 2 is attached to the upper end of a back support 7 so as to be tiltable backward.

As shown in FIG. 1(D), a front-rear long receiving portion 8 is formed at the upper end of the front frame 6, and the seat 1 is connected to the receiving portion 8 so as to be tiltable backward. As shown in FIGS. 1(A) and 2(C), an armrest 9 can be attached to the upper end of the back support 7 as an optional item.

As clearly shown in FIGS. 2B and 2C, the left and right back braces 7 are inclined so as to shift forward as they go up when viewed from the side, and are spaced apart from each other as they go up when viewed from the front. It is slanted so that it spreads out.

As clearly shown in FIG. 2(B), the back support 7 stands up from the base 5 in a backward tilted posture in a side view, and bends into a dogleg shape so that it changes to a forward tilted posture at approximately the height of the seat 1. When viewed from the front, as shown in FIG. there is

The upper part of the back support 7 is positioned on the left and right outside of the lower part of the backrest 2, and the backrest 2 is attached to the upper end part of the back support 7 so as to tilt backward with the lower part as a fulcrum. Therefore, as shown in FIG. 2(B), the pivot point O1 (rotation center) of the backrest 2 is positioned within the thick portion of the backrest 2 . As shown in FIG. 2B, the pivot point O2 of the seat 1 is also positioned within the thick portion of the seat 1. As shown in FIG.

As shown in FIG. 1(D), the lower half of the front frame 6 and the back support 7 are inclined in a front view and a side view so as to expand in a diagonal direction. In other words, the front frame 6 and the back strut 7 are erected in a substantially diagonal direction from the corners of the square base 5 in a plan view. In other words, the four frames 6, 7 appear to converge below the seat 1 toward the base 5. As shown in FIG.

The left and right front frames 6 are aluminum die-cast products or resin-molded products, and are integrally formed with a front substrate 6a that is approximately square (horizontally long rectangle) in a plan view. On the other hand, the left and right back braces 7 are separated from each other, and are integrally formed with rear base bodies 7a each having a substantially rectangular shape in a plan view. The left and right rear base bodies 7a overlap so as to be continuous in the left-right direction, and the left and right rear base bodies 7a and the front base bodies 6a overlap in the front-rear direction.

Therefore, the front substrate 6a and the left and right rear substrates 7a are overlapped as if forming one member as a whole, and the base is completely covered by these three. Therefore, the two front frames 6 and the two back supports 7 have the appearance of standing up in a diagonally inclined posture from the base, which is substantially rectangular in plan view, and the base must be turned upside down. It is not visible.

(2) Attachment Structure of Backrest Next, the attachment structure of the backrest 2 to the back support 7 will be described with reference to FIG. 3 and subsequent drawings. As shown in FIG. 3A, the backrest 2 has a structure in which a back cushion 11 is superimposed on the front surface of an inner back shell 10 made of resin. It is attached to the upper end of the back support 7 via the so as to be tiltable backward. As shown in FIG. 6(A), the lower portion of the back inner shell 10 is gently bent in a V-shape in a state of being concave forward when viewed from the side. The back cushion 11 is covered with a skin material such as cloth. The back surface of the back inner shell 10 is also covered with a skin material. Therefore, the skin material is formed in the shape of a bag.
As shown in FIGS. 3 and 5, the front surface of the back inner shell 10 is formed with a large number of forward recesses 10c formed by groups of vertically elongated ribs 10a and horizontally elongated ribs 10b.

For example, as shown in FIG. 4, the back tilting unit 12 includes an outer bracket 13 that moves integrally with the back inner shell 10, an inner bracket 14 that is arranged inside the outer bracket 13 and fixed to the back support 7, A side bracket 15 is provided so as to overlap the outer surface of the outer bracket 13, and these brackets are substantially V-shaped in side view in accordance with the curvature of the back inner shell 10.例文帳に追加The outer bracket 13 is an example of a movable bracket described in the claims, and the back inner bracket 14 is an example of a fixed bracket described in the claims.

Left and right side portions of the bent portion of the back inner shell 10 are formed with lateral recesses 16 into which the outer brackets 13 are fitted. The portion of the back inner shell 10 where the lateral recess 16 is formed bulges slightly forward, but the portion of the back inner shell 10 where the lateral recess 16 is formed does not have a forward recess 10c. Basically , the thickness of the back inner shell 10 is almost unchanged to form the sideways concave portion 16 . Further, even if the portion in which the sideways concave portion 16 is formed swells slightly toward the front, the bulge is hidden by the back cushion 11, so the presence of the bulge cannot be visually recognized from the outside. Therefore, there is no appearance problem such as a part of the backrest 2 becoming thick due to the formation of the lateral recess 16 .

An outward projection 15a is formed in the lower half of the side bracket 15, and as shown in FIG. , and the outward convex portion 15a abuts or is in close contact with the inner surface of the back support 7. As shown in FIG. In other words, there is substantially no gap between the outward projections 15a of the side brackets 15 and the inner surface of the back support 7, or there is only a slight gap.

The outer bracket 13 and the inner bracket 14 are connected by laterally elongated pivot pins 17, and as shown in FIG. A spring 18 is arranged above the pin 17 . A burring portion 19 for positioning the spring 18 is formed between the outer bracket 13 and the inner bracket 14 .

The outer bracket 13 and the inner bracket 14 are provided with side plates 13a and 14a, respectively. The outer bracket 13 also has a front plate 13b and a rear plate 13c and is formed in a tubular shape as a whole, and the inner bracket 14 is formed in a gutter shape.

As shown in FIGS. 3(A) and 6(A), left and right laterally long reinforcing plates 20 are superimposed on the bent portions of the back surface of the back inner shell 10, and as shown in FIG. , the end portion of the reinforcing plate 20, the back inner shell 10, and the upper and lower portions of the rear plate 13c of the outer bracket 13 are fastened together with screws 21. As shown in FIG.

As shown in FIG. 6A, the screws 21 are arranged on both upper and lower sides of the inner bracket 14 . A recessed groove 22 is formed on the back surface of the back inner shell 10 to hold the reinforcing plate 20 so that it cannot be displaced. is also positioned.

A downward projecting portion 20a extending to the lower end of the outer bracket 13 is formed at both left and right ends of the reinforcing plate 20, and the downward projecting portion 20a is fastened together to the back inner shell and the outer bracket 13 by a lower screw 21. there is When a seated person leans back on the backrest 2, a large moment is applied to the lower end of the backrest 2, but the presence of the reinforcing plate 20 ensures strength to resist the moment.

For example, as shown in FIG. 4(B), the rear plate 13c of the outer bracket 13 is formed with a watermark hole 24 that opens rearward, and fastening with the screw 21 is performed in the upper and lower directions with the watermark hole 24 interposed therebetween. It is done in two places. The pivot pin 17 is tightly inserted through the outer bracket 13 and the inner bracket 14 . Note that the pivot pin 17 may be fixed to either one of the outer bracket 13 and the inner bracket 14 by welding, crimping, or the like.

In addition, the pivot pin 17 has an exposed portion protruding outside the outward protrusion 15a of the side bracket 15, and this exposed portion is fitted into a bearing groove 25 formed in the back support 7 by dropping. . As shown in FIG. 5(B), the bearing groove 25 has a deep groove portion 25a that is open to the front and to the left and right sides, and that extends downward and opens inward toward the backrest 2. The exposed portion of the pin 17 is stably supported by the deep groove portion 25a.

Needless to say, the tilting unit 12 for the back is first set in the sideways recess 16 of the back inner shell 10, while the back support 7 is attached in a predetermined state in advance, and the pivot pin 17 is fixed. The backrest 2 is rotatably attached to the upper end portion of the back support 7 by fitting the exposed portion into the bearing groove 25 from the near side and dropping it into the deep groove portion 25a.

As already mentioned, the pivot pin 17 also passes through the inner bracket 14 . 4, a horizontal bolt 26 is inserted from the outside into a portion of the back support 7 below the bearing groove 25, and the horizontal bolt 26 is screwed into the inner plate 14a of the inner bracket 14. ing.

The lateral bolt 26 is a stepped bolt, and when fully screwed into the inner bracket 14, the inner bracket 14 is connected to the back support 7 while maintaining a slight clearance with the outer plate 13a of the outer bracket 13. . Therefore, although the inner bracket 14 is arranged inside the outer bracket 13 , it is held by the horizontal bolts 26 so as not to move back and forth and not to move up and down, and is integrated with the back support 7 . are also held so as not to come off from the bearing groove 25 . Also, as can be understood from FIG. 6A, (the outer bracket 13 can be tilted backward by compressing the spring 18.)

As can be understood from FIGS. 6B and 6C, the upper and lower end portions of the side bracket 15 are formed with upper and lower engaging claws 27 protruding toward the outer bracket 13, while the outer bracket 13 has an outer side plate 13a formed with an engaging hole 28 with which an engaging claw 27 is engaged.

Therefore, the side bracket 15 rotates integrally with the outer bracket 13 . Since the lateral bolts 26 pass through the side brackets 15 and the outer brackets 13, the side brackets 15 and the outer brackets 13 are allowed to rotate integrally with the backrest 2. , there is an arcuate hole 29 with the pivot pin 17 as the center of the radius of curvature, as an escape hole described in claim 4 .

(3) Top Cover/Summary As shown in Fig. 1(A), the armrest 9 can be attached to the upper end of the back support 7. However, when the armrest 9 is not attached, the backrest can be removed as shown in Fig. 5, for example. The upper part of the column 7 is covered with an upper cover 30. - 特許庁The outer surface of the upper cover 30 is flush with its lower portion. Therefore, the portion covered with the upper cover 30 is stepped down from the lower portion and is slightly thinner. For example, as shown in FIGS. 3(A) and 3(C), the step portion is denoted by reference numeral 7b.

The upper cover 30 has a groove shape so as to completely cover the back pillar 7 from the left and right outsides (more precisely, it has a groove shape that opens downward and inward). Front and rear lateral engagement claws 31 are fixed to the inner surface of the upper portion, while cut-open grooves 32 are formed on both front and rear surfaces of the back post 7 so that the lateral engagement claws 31 are fitted and engaged. The front and rear lateral engaging claws 31 are integrally connected via a base end plate 31a, and the base end plate 31a is fixed to the inner surface of the upper cover 30 with screws 33 (see FIG. 5B).

On the other hand, a stepped portion 32a into which the hook portion of the sideways engaging claw 31 is fitted is formed at the end portion of the cut-open groove 32 near the backrest 2 . Therefore, the upper cover 30 can be attached to the back support 7 simply by fitting it in the back support 7 from the lateral direction and pressing it strongly so as not to fall off.

Since the back tilting unit 12 is stored inside the backrest 2, the back tilting unit 12 cannot be visually recognized from the outside. Therefore, although the chair has a rocking function in which the backrest 2 tilts backward, a simple appearance can be achieved.

Further, since the backrest 2 is connected to the back support 7 at the most forward part (lumbar support part), there is almost no slippage between the seated person and the backrest 2 even if it is rocked. Therefore, it is possible to realize a comfortable rocking state without causing discomfort. Using the bolts 26 to hold the inner bracket 14 in a non-rotatable manner as in the embodiment has the advantage of simplifying the structure. Instead of the coil spring 18 made of wire, it is also possible to use an elastic body such as rubber resin.

The rotation range of the outer bracket 13 is restricted by the inner bracket 14 . Therefore, the backrest 2 tilts forward and backward, and is defined by the inner bracket 14 and the outer bracket 13 .

As described above, the front surface of the back inner shell 10 is covered with the back cushion 11. As shown in FIG. Although not shown, it also covers the rear surface (back surface) of the back inner shell 10 (the reinforcing plate 20 is covered with the back cushion 11 and cannot be seen through). A portion of the back cushion 11 covering the outer peripheral surface and the rear surface of the back inner shell 10 is thin with a thickness of several millimeters.

As clearly shown in FIG. 7B, the back cushion 11 is also inserted into the space between the back inner shell 10 and the back support 7, and the outward projections 15a of the side brackets 15 are positioned in the back cushion 11. It penetrates through the formed escape hole 11a. Since the back cushion 11 is elastic and the skin material actually has a thickness of several millimeters, the space between the back inner shell 10 and the back support 7 is filled with the back cushion 11 and the skin material. is in a state of Therefore, it is possible to prevent a gap from appearing between the backrest 2 and the back support 7, thereby improving the appearance.

Further, since the gap between the backrest 2 and the back support 7 is very small and the gap is filled with the back cushion 11 and the skin material, it is impossible for a person to insert his or her fingertips into the gap. Yes, there are no safety issues.

Also, since the pivot pin 17 is dropped into the bearing groove 25 of the back support 7, the mounting work can be done quickly. This point is one of the great advantages of the present embodiment.

(4) Others Although the embodiments of the present invention have been described above, the present invention can be embodied in various other ways. For example, a torsion bar, a torsion spring, or a leaf spring can be used as the spring means. Also, the outer bracket and the inner bracket are not necessarily required. If strength permits, it is also possible to fix the pivot pin directly to the backrest, or to insert the pivot pin fixed to the back support directly through the backrest.

As the pivotal support means (connecting means) of the backrest, it is not always necessary to use the pivotal support pin as in the embodiment. For example, it is possible to fix a cylinder to the side surface of the backrest and insert a pin provided on the back support into the cylinder.

Further, the object of application of the present invention is not limited to swivel chairs, but can also be applied to fixed-legged chairs (chairs with a fixed seat height) that are frequently used in performance banquet halls and the like. The structure of the backrest (and seat) can also be set arbitrarily. For example, a structure in which a mesh is stretched on the frame can also be adopted. It is also possible to integrally provide the back support with the base, and it is also possible to manufacture the front frame, back support, and base as one piece. Although it is outside the scope of the present invention, it is possible to incorporate the spring means into the recess provided in the back support (however, if the spring means is incorporated in the backrest as in the present invention, the back support can be made slim and aesthetically pleasing). can be improved).

The present invention can be embodied in a chair. Therefore, it can be used industrially.

2 backrest 5 base 7 back support 10 back inner shell
10a Vertical rib
10b Horizontal rib
10c forward recess
REFERENCE SIGNS LIST 11 back cushion 12 tilting unit for back 13 outer bracket 14 inner bracket 15 side bracket 15a outward protrusion 16 lateral recess
17 pivot pin 18 coil spring as an example of spring means 20 reinforcing plate 25 bearing groove 26 horizontal bolt 29 arc hole (escape hole)
30 top cover

Claims (6)

A seat, a backrest , and left and right back supports arranged closely or in close proximity to the sides of the backrest ,
The backrest has a back inner shell made of synthetic resin and a back cushion arranged in front thereof, and the back inner shell has a large number of forward facing concave portions surrounded by a group of longitudinally elongated ribs and a group of horizontally elongated ribs. A desired thickness is ensured by providing a group of places,
and the backrest is connected to the back support so as to tilt backward against the spring means when the seated person leans back,
lateral recesses that are open toward the back support are formed in left and right side portions of the back inner shell, and the spring means are arranged in the lateral recesses;
Further, the portion of the back inner shell provided with the sideways recess does not have the forward facing recess, and the portion of the back inner shell provided with the sideways recess does not protrude backward.
Chair. A movable bracket fixed to the lateral recess of the backrest and a fixed bracket fixed to the back support are arranged in the lateral recess of the backrest, and the spring means is arranged between the movable bracket and the fixed bracket. is placed,
A chair as claimed in claim 1. A seat, a backrest, and left and right back supports arranged closely or in close proximity to the sides of the backrest,
The backrest is connected to the back support so as to tilt backward against the spring means when the seated person leans back,
A configuration in which the backrest is formed with a lateral recess that opens toward the back support, and the spring means is disposed in the lateral recess,
A movable bracket fixed to the lateral recess of the backrest and a fixed bracket fixed to the back support are arranged in the lateral recess of the backrest, and the spring means is arranged between the movable bracket and the fixed bracket. is placed,
Further, a pivot pin having an exposed portion that enters the spine is fixed to the fixed bracket,
A bearing groove is formed in the back support so that the exposed portion of the pivot pin can be dropped from the front,
and the fixing bracket is fixed to the back strut by a bolt arranged below the pivot pin, and the bolt is inserted from the outer surface of the back strut.
chair . The movable bracket has a substantially cylindrical shape having a front plate, a rear plate, and inner and outer plates.
The fixed bracket has a rear plate and left and right side plates, and is arranged inside the movable bracket. An outer plate of the movable bracket is formed with a relief hole through which the bolt penetrates. The hole is elongated to allow the movable bracket to rotate,
A chair according to claim 3. The movable bracket and the fixed bracket are made of metal, and the movable bracket is provided with a synthetic resin side bracket that is in close contact with the side surface of the back support,
A chair according to any one of claims 2-4. The backrest has a structure in which a back cushion is attached to a back inner shell made of synthetic resin,
A metal reinforcing plate is arranged on the back surface of the back inner shell and extends continuously to both left and right ends thereof, and the reinforcing plate is fitted into a groove formed in the back inner shell,
The reinforcing plate, the back inner shell, and the movable bracket are fastened together with screws, and the reinforcing plate is covered with a skin material.
A chair according to any one of claims 2-5.

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