JP2003079476A - Chair - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a strong structure concerning the seat back of a chair and also to easily attach a lumber support mechanism and a headrest. SOLUTION: The seat back 5 of the chair has a three-layer structure consisting of a back frame 20, a seat back board 21 positioned at this side of it and a rear cover 22 positioned at the rear side of the back frame 20. The rear cover 22 is fixed to the back frame 20 and the seat back board 21 is attached to the rear cover 22 and the back frame 20. The strong structure is obtained in the seat back 5 since the rear cover 22 is firmly fixed to the back frame 20. Besides, a space is provided between the seat back board 21 and the rear cover 22 so that the lumber support mechanism is easily built inside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chair having a backrest.

[0002]

2. Description of the Related Art In the case of a rocking chair having a backrest tilted backward, a back frame (back strut) is often set up behind the seat and a backrest plate is attached to the back frame.

In this case, looking at the relationship between the back frame and the backrest plate, the lower part of the backrest plate is often fixed to the back frame by means such as screwing or fitting.

On the other hand, Japanese Patent No. 3038174 discloses that
Back frame with back frame (back girder in the name of the publication)
A lumber support mechanism is provided on the back frame by flexibly deforming a portion of the backrest plate that is in contact with the projecting member, while the back frame is provided with a projecting member that is convex in a forward direction and is gently curved in a side view. Is listed.

[0005]

In the structure in which the lower portion of the backrest plate is fixed to the back frame, the height of the backframe must be increased in order to increase the mounting strength of the backrest plate. There is a problem that it is exposed on the back side of the board and spoils the aesthetics.

It is also known that the lower part of the back frame is fixed to the upper part of the back cover and the backrest plate is attached to the front surface of the back cover. In this case, the back frame and the back cover have a special structure. Therefore, there is a problem that not only is it time-consuming to manufacture, but also it is difficult to attach the headrest and the lumbar support mechanism.

On the other hand, when the lumbar support mechanism is provided, a portion of the backrest plate that abuts the waist of the seated person needs to be curved in a mountain shape in a side view. Therefore, in the configuration of the above-mentioned Japanese Patent No. 3038174, the backrest plate is required. As a structure integrated with the seat plate, by forming horizontal slits in multiple steps in the part of the back plate that hits the waist of the seated person, the part with the slits deforms in a state that follows the protruding part of the back frame. I am trying to do it.

However, in the structure in which the back plate is integrally provided with the seat plate as in this Japanese Patent No. 3038174,
There is a problem that it cannot be applied to a rocking chair of a type in which the backrest leans backward while being independent of the seat board.

The present invention aims to improve the present situation.

[0010]

A chair according to a first aspect of the present invention comprises a seat and a backrest, and the backrest comprises:
It has a three-layer structure consisting of a back frame that stands up behind the seat, a backrest plate (back inner member) placed on the front side of this back frame, and a back cover (back outer member) placed on the back side of the back frame. There is.

According to the invention of claim 2, in claim 1,
The back cover is attached to the back frame, while the backrest plate is attached only to the back frame, the back cover only, or both the back frame and the back cover.

According to a third aspect of the invention, in the second or third aspect, there is a space open to the outside between the backrest plate and the back frame.

According to the invention of claim 4, claim 1 to claim 3
In any one of the above, the back cover is fixed to the back frame, while the backrest plate is attached to the back cover or the back frame so that the backrest plate cannot move back and forth and the bottom frame cannot move. Since the backrest plate is attached to the back frame or the back cover in such a manner that it cannot move back and forth and can move up and down, the backrest plate is allowed to flex and deform.

According to a fifth aspect of the present invention, on the back surface of the upper portion of the backrest plate, there is provided an upper mounting portion that fits into a receiving portion provided on the front surface of the upper portion of the back cover from above, and by fitting into the receiving portion. An engagement claw that engages with the receiving portion and holds it in a non-removable manner is provided.

On the other hand, on the back surface of the lower part of the backrest plate, the backrest plate can be moved up and down without being separable back and forth by fitting it into the space between the horizontal elongated member provided on the back frame and the back cover from above. A lower mounting portion for holding is formed, and a lower end of the lower mounting portion is provided with a claw that is hooked from below to the horizontally long member of the back frame,
Further, a lumbar support mechanism is attached to the back frame to press the backrest plate forward to bend and deform it.

[0016]

When the backrest has the three-layer structure of the back frame, the back plate and the back cover as in the present invention, the back frame can be extended to the upper part of the backrest, so that the backrest is sturdy as a whole. Can be structured.

Particularly, by fixing the back cover to the back frame as in claim 2, it is possible to improve the mounting strength of the back cover.

The back plate can be attached to the back frame or the back cover, while
Since there are few restrictions when attaching the back cover to the back frame, it is possible to improve the flexibility of the structure and design of the back plate, the back frame and the back cover.

Although it is possible to make the peripheral edge of the back frame and the backrest plate closely contact with each other, an outer opening may be provided between the backrest plate and the back cover as in claim 3. By doing so, it becomes possible to visually recognize the back frame, and it is possible to give the user a mechanical impression.

Further, as in claim 5, it is possible to easily realize the arrangement of the lumbar support mechanism between the backrest plate and the back cover and the formation of the receiving portion into which the column of the headrest is inserted.

By the way, from the viewpoint of sitting comfort when a person leans against the backrest, it is preferable that the backrest plate is flexibly deformed so as to follow the body shape of the person to improve the fit. In this respect, according to the fourth aspect of the invention, the backrest plate is in a state of allowing the flexural deformation, so that the sitting comfort can be improved.

According to the fifth aspect of the invention, the lumbar support mechanism pushes the backrest plate to obtain a fit according to the physique and taste of the seated person, which is particularly preferable. In this case, as for the backrest plate, the upper mounting part should be fitted into the receiving part of the back cover from above, and the lower mounting part should be inserted between the horizontally long member of the back frame and the back cover. Easy to do.

Further, since the pressing portion of the lumbar support mechanism is attached to the back frame, it is possible to prevent the pressing portion of the lumbar support mechanism from being exposed to the back side and improve the safety.

[0024]

Embodiments of the present invention will now be described with reference to the drawings.

(1). Outline (FIGS. 1 to 6) First, an outline of the chair will be described with reference to FIGS. 1 to 5. 1 is a right side view, FIG. 2 is a front view, FIG. 3 (A) is a rear view, FIG. 4 is a separated perspective view of members, and FIG. 5 is a partial vertical side view.

The chair includes a leg 2 on which a leg column (gas cylinder) 1 is erected, a seat 3, an armrest device 4, a backrest 5, and a backrest 5.
And a headrest 6. A base 7 that opens upward is fixed to the upper ends of the leg columns 1, and an intermediate member 8 that spreads like a wing in a front view and a seat 3 are arranged above the base 7.

Although not described in detail, the seat 3 has a structure in which a cushion is stretched on a seat plate (seat inner member) made of synthetic resin. Although not described in detail, both left and right side portions of the seat plate are intermediate members. It is attached so that it can move back and forth.

A pair of left and right bracket portions 8a and 8b are provided on the front and rear portions of the intermediate member 8 so as to project downward, and the front bracket portion 8a is connected to the base 7 by a first shaft 9 extending in the left and right direction. Has been done. Hole 1 in which the first shaft 9 fits into the base 7
0 is a long hole in the longitudinal direction.

The front part of the swing frame 11 is connected to a substantially middle part in the front and rear of the base 7 by a second shaft 12 extending in the left-right direction. A rear bracket 8b of the intermediate member 8 is provided in the middle of the swing frame 11 in the front-rear direction.
Are linked by. As shown in FIGS. 4 and 5,
Two torsion springs (kick springs) 14, which are left and right, are arranged in a distributed manner in an area of the second shaft 12 located inside the base 7 as an example of elastic supporting means. Supported from above by the receiving member 15,
The rear bracket 8b of the intermediate member 8 contacts the other end of the torsion spring 14 from above.

Therefore, the oscillating frame 11 includes the torsion spring 1
4, the intermediate member 8 and the seat 3 retreat while tilting backward in conjunction with the rearward tilting of the swing frame 11 (that is, the seat 3 synchronizes with the backrest 5). The initial elastic force of the torsion spring 14 can be adjusted by the knob 16 engaged with the receiving member 15.

The oscillating frame 11 is formed in a substantially L shape in a side view and has a rising portion 11a at the rear portion. In the present embodiment, a light alloy such as aluminum (other metal such as iron may be used). It is manufactured by die casting and molding of synthetic resin.

The rearwardly inclined portion has a substantially triangular cross section and is opened inward, and a reinforcing rib 17 is provided inside. Further, the rising portion 11a is formed in a triangular shape (or teardrop shape) in a plan view so as to be smoothly continuous with the inclined portion. A recess 18 is formed on both front and rear surfaces thereof, and a rib 19 is formed in the recess 18. It is provided in multiple stages.

The backrest 5 is arranged on the back frame 20 (back strut) 20 attached to the swing frame 11, a backrest plate (back inner member) 21 arranged on the front side of the back frame 20, and on the back side of the back frame 20. And a back cover (back outer member) 22. A cushion 23 is stretched on the front surface of the backrest plate 21.

As shown in FIGS. 3A and 3B, a large number of small recesses 24 are formed on the back surface of the back frame 20. A normal back cover often has a smooth shape or a satin-like shape, but in this case, not only the change is poor, but also sink marks due to shrinkage during molding may be noticeable.

On the other hand, if a large number of recesses 24 are provided on the back surface of the back cover 22 as in this embodiment, the illumination from the ceiling is reflected and absorbed well, so that the appearance is good due to the accent effect and at the time of molding. It has the advantage of absorbing sink marks and scratches.

The details of the backrest 5 will be described below with reference to FIGS. 6 is a front view of the backrest 5 without the backrest plate 21, FIG. 7 is a vertical sectional side view of the backrest, FIG. 8 is a vertical sectional side view with the cushion 23 omitted, and FIG. 9A is a back frame. 20 and the swinging frame 11 are separated front views, FIG. 10 is a sectional side view of the back frame 20, the backrest plate 21, and the back cover 22, and FIGS. 11 and 12 are perspective views showing the mounting state of the backrest plate 21.
In FIG. 13, (A) is a plan view and (B) is a backrest plate 21.
FIG. 3 is a plan view showing the back cover 22 separated from the above.

(2). Basic structure of the backrest As described above, the backrest 5 is provided with the metal back frame 20, the synthetic resin backrest plate 21, and the synthetic resin back cover 22. A lumbar support mechanism 25 is attached to the frame 20 so as to be vertically movable.

For example, as shown in FIGS. 9 and 10, the back frame 20 is provided with left and right support columns 20a, and the left and right support columns 20a are connected by an upper lateral elongated member 20b and a lower lateral elongated member (lower engaging portion) 20c. Has been done. Upper horizontal member 20b
Is a U-shaped cross section and the lower lateral member 20c is a round pipe, but it may have another cross section. Further, an intermediate laterally elongated member may be arranged.

The lower ends of the left and right columns 20a of the back frame 20 are fitted into the holes formed in the rising portions 11a of the swing frame 11 and fixed with screws 26.
In this case, the screw 26 is screwed in at the location of the recess 18, so that the head of the screw 26 is not conspicuous and the appearance is good.

For example, as shown in FIG. 6, a horizontal rib 27 is formed on the upper portion of the back cover 22 so as to project forward and to the left and right, and a pair of left and right downward opening cylinders are connected to the horizontal rib 27. A portion 28 is formed, and the upper end of the pillar 20 a of the back frame 20 is fitted into the downward opening tubular portion 28 and fixed with a screw 29.

Further, as shown in FIGS. 6 to 8 and 10, a bracket portion 30 which is fitted to the lower laterally long member 20c of the back frame 20 from above is integrally provided on the lower portion of the back cover 22. Is fixed to the lower laterally long member 20c with a screw 31.

As described above, since the back frame 20 extends to the upper part of the backrest 5 and the front portion of the back cover 22 is fixed to the back frame 20, the back cover 22 is attached to the back frame 20. Can be firmly fixed.

As described above, a cushion 23 is stretched on the front surface of the backrest plate 21, and the surface of the cushion 23 is covered with a cloth (skin material such as cloth) 32.

Further, as shown in FIGS. 7, 8, 10 and 11, for example, a horizontal piece 35 is provided on the upper part of the backrest plate 21, which is located above the horizontal rib 27 of the back cover 22 and has a left-right longitudinal direction.
Are projected rearward, and cylindrical upper mounting portions 34 are projected downward at both left and right ends of the horizontal piece 35, which are connected to the horizontal ribs 27 of the back cover 22 to form a cylindrical upper portion. It is fitted into the receiving portion 35 from above.

In this case, the upper mounting portion 34 and the backrest plate 2
1 is integrally connected to 1 by a plate-shaped portion 34a for reinforcement, while a slit 36 into which the plate-shaped portion 34a is fitted is formed in the upper receiving portion 35 of the back cover 22.

Further, an upper engaging claw 37 which is hooked and engages with the lower end surface of the upper receiving portion 35 is integrally provided at the tip of the upper mounting portion 34. Therefore, when the upper mounting portion 34 is fitted into the upper receiving portion 35, the backrest plate 21 is held so as not to come out upward. As shown by a black arrow in FIG. 11, the backrest plate 21 is pushed with the engaging claws 37 pushed from the outside to the inside.
By pushing upward, the backrest plate 21 can be removed.

Vertical ribs 38 projecting toward the back surface of the backrest plate 21 are formed on both left and right sides of the back cover 22, and the vertical ribs 38 are cut at a height that is very low at the engaging claws 37. The notch portion 38a is provided so as not to interfere with the push-bend operation of the engaging claw 37 (may be completely interrupted).

Since the backrest 5 has a three-layer structure and a gap is provided between the backrest plate 21 and the back cover 22,
The engaging means for preventing the backrest plate 21 from coming off, such as the engaging claw 37, can be operated from the outside, and as a result, the backrest plate 21 can be easily attached and detached.

On the lower portion of the backrest plate 21, there is integrally formed a lower mounting portion 39 which is inserted into the space between the lower horizontal member 20c of the back frame 20 and the back cover 22 from above. The lower mounting portion 39 extends long in the up-down direction so that the backrest plate 21 can move to the front side, and at the lower end thereof,
A claw 39c for restricting the forward movement limit of the backrest plate 21 by being hooked on the lower horizontal member 20c of the back frame 20 is provided.

Further, as shown in FIG. 12, the backrest plate 2
1 has a slit 40 that surrounds the upper part of the lower mounting portion 39.
Therefore, the lower mounting portion 38 can be easily deformed so as to move back and forth. In other words, with the lower mounting portion 39 engaged with the lower laterally long member 20c, the lower portion of the backrest plate 21 can be easily bent and deformed so as to be pushed forward.

When mounting the backrest plate 21, the lower mounting portion 39 is first inserted between the lower horizontal member 20c and the back cover 22, and then the upper mounting portion 34 is elastically attached to the upper receiving portion 35 of the back cover 22. It will be fitted against. To remove it, reverse the order.

The space between the back surface of the backrest plate 21 and the lower mounting portion 39 is defined by the lower horizontal member 20c of the back frame 20.
Since the backrest plate 20 is larger than the diameter of the backrest plate 20, the backrest plate 20 is allowed to move back and forth in its lower portion. Therefore, the backrest plate 20 can be flexibly deformed even in a side view.
As a result, there is an advantage that the seated person is highly fitted.

The cloth 32 covering the cushion 23 is formed in a bag shape so as to cover the entire back surface of the backrest plate 21, and the horizontal ribs 27 and the lower mounting portion 39 are exposed from the cloth 32. Further, the horizontal piece 35 of the backrest plate 21 is formed with long slits 41 on the left and right,
By inserting the edge portion 32a of the cloth 32 into the slit 41, the cloth 32 is beautifully processed at the location of the horizontal piece 35.

The headrest 6 is provided with left and right columns 42, and the left and right columns 42 are inserted into and mounted on a pair of upper and lower receiving cylinders 45 provided on the front surface of the back cover 22 and fixed with screws. . Since the backrest 5 has a three-layer structure, the headrest 6 can be easily attached.

(3). Structure of the lumbar support mechanism Next, the lumbar support mechanism 25 will be described with reference to the drawings starting from FIG.

In FIG. 14, (A) is a partial plan view and (B) is a plan view.
Is a partial front view, (C) is a partial right side view, FIG. 15 is a front view of a main part, FIG. 16 is a front view of a side edge portion of the backrest plate 21, and FIG. 17 is a sectional view taken along line XVII-XVII of FIG. FIG. 18, (A) is a sectional view taken along line XVIII-XVIII of FIG. 15, (B) is a sectional view of members, (C) is a partially cutaway view of (A), and FIG.
18 is a sectional view taken along line XIX-XIX in FIG. 18, and FIG. 20 is line XX- in FIG.
21 is a sectional view taken along line XXI-XXI of FIG. 19, and FIG. 21B is a schematic diagram showing the operation.

The lumbar support mechanism 25 is designed to allow the seated person to take a correct posture in accordance with his / her physique by projecting forward the part of the backrest plate 21 which particularly hits the waist of the seated person. is there.

The lumbar support mechanism 25 of this embodiment
Is a slide case (an example of an elevating means) 45 mounted on the support column 20a of the back frame 20 so as to be vertically movable, a connecting body (an example of a connecting means) 46 that integrally connects the left and right slide cases 45, and a slide. A pressing arm (an example of a pressing unit) 47 provided on the case 45, an interlocking shaft (an example of an interlocking unit) 48 for rotating the left and right pressing arms 47 together, and an operation of simultaneously operating the left and right pressing arms 47. And a handle 49 which is an example of a means.

As shown in FIG. 19, the slide case 45
A slider 50, which is made of a synthetic resin and is split into two, is mounted inside the. Further, as shown in FIGS. 15 and 17, the slider 50 is provided with a bending claw 51 that extends downward (or upward) and has a tip with a chevron cross section. A rib 52 provided at a rear position of the slide case 45 is formed with a concave-convex portion 52a having a sawtooth shape in a side view, which engages with the bending claw 51.

Therefore, when a certain amount of upward or downward force is applied to the slide case 45, the bending claw 51 can be elastically deformed to move the lumbar support mechanism 25 up and down, and there is no external force in the vertical direction. Then, the lumbar support mechanism 25 stops at that height. As a result, the waist of a seated person can be accurately supported regardless of the difference in height.

The left and right ends of the interlocking shaft 48 rotatably pass through the slide case 45 and the slider 50.
The interlocking shaft 48 is bent in a crank shape between the left and right slide cases 45. As shown in FIG. 18C, the crank portion of the interlocking shaft 48 is brought into contact with the connecting plate 46 so that the rotation limit in one direction is increased. It is regulated.

As shown in FIG. 21, the slide case 45
A receiving case 53 having a generally U-shaped cross section and extending in the vertical direction is fixed to the left and right side surfaces of the above, and the pressing arm 47 having a generally U-shaped cross section is covered from the front side of the receiving case 53. Then, the interlocking shaft 48 is provided above the pressing arm 47.
The left and right end portions of the pierce through the interlocking shaft 48 and the pressing arm 4
7 is fixed.

Therefore, the pressing arm 47 rotates integrally with the interlocking shaft 48. The end of the interlocking shaft 48 penetrates the receiving case 53, and the receiving case 53 also plays the role of a bearing for the interlocking shaft 48.

A gear 55 and a cam 56 are rotatably supported on a vertically middle portion of the receiving case 53 by a left and right longitudinal support shaft 54. The support shaft 54, the gear 55, and the cam 56 rotate together.

As shown in FIG. 21, the pressing arm 47 is supported on the outer peripheral surface of the cam 56.
By forming a plurality of (six) cam surfaces 56a having different distances from the shaft center on the outer peripheral surface of 6, when the cam 56 rotates, it rotates about the end of the interlocking shaft 48 in the pressing arm 47. Is set to.

At the lower end of the pressing arm 47, the backrest plate 2 is provided.
A roller 57 that contacts the back surface of the roller 1 is provided. Since the backrest plate 21 is curved in a forward concave shape in plan view, the backrest plate 21 shown in FIG.
As shown in, the roller 57 is formed in a tapered shape. Further, as shown in FIG. 16, slits 58 that are bent in a stepwise manner are formed in multiple steps on the left and right sides of the backrest plate 21, and the stepwise portion of the slits 58 is the roller 5.
It is set to hit 7.

As shown in FIG. 18, a seesaw type rotating member 59 fixed to the end of the interlocking shaft 48 is arranged inside the receiving case 53, and the rotating member 59 has a gear 55.
A claw member 60 that meshes with is attached. Therefore, when the rotating member 59 is rotated, the gear 55 and the cam 56 can be rotated.

In this case, the teeth of the gear 55 have an asymmetrical trapezoidal shape so that when the rotating member 59 is rotated in the direction of the black arrow, the gear 55 intermittently rotates only in the counterclockwise direction in right side view. An elastic stopper 61 that prevents the reverse rotation of the gear 55 is attached to the receiving case 53.

Then, the handle 4 is attached to the left and right turning members 59.
The left and right ends of 9 are fixed with screws 62. Handle 49
Is formed so as to cover the back cover 22 from the rear side. In addition, the rising portions 49 are provided at the left and right ends of the handle 49.
a is provided, and the upper end of the rising portion 49a is fixed to the rotating member 59. A space is provided between the handle 49 and the back cover 22 so that a person can hold the handle 49 and hang clothes or towels on the handle 49.

(4) Movement of the lumbar support mechanism When the handle 49 is held by hand and rotated to the front side, the rotating member 59 rotates and the cam 56 rotates intermittently in the position direction. Since the cam 56 is a rotary type, the backrest plate 21 can be pushed out little by little by the rotation of the pressing arm 47, and at the same time, the backrest plate 21 is pushed out to the maximum protruding position and then the handle 4 is pushed.
When 9 is rotated, the backrest plate 21 returns to the most retracted position.

When the handle 49 is held by hand and a certain amount of force is applied to push and pull in the up and down direction, the lumber support mechanism 25 is moved up and down at an extremely fine pitch by the action of the bending claw 51 and the uneven portion 52a. Can be made.

As in this embodiment, the rising portions (the hanging portions when viewed from the end) 49 are formed at the left and right ends of the handle 49.
When a is provided, the handle 49 can be easily grasped in the seated state, and therefore, there is an advantage that the height and the protrusion amount of the lumbar support mechanism 25 can be easily adjusted in the seated state. In the present embodiment, the handle 49 is operated with the upper half of the body lifted from the backrest 5.

In the case of Japanese Patent No. 3038174, since the right and left intermediate portions of the backrest plate are supported by the projections, the backrest plate 21 hardly bends and deforms, and therefore there is a problem that the fitted backrest plate is poor. However, in the present embodiment, since the left and right ends of the backrest plate 21 are pushed out by the pressing arms 47, the backrest plate 21 can be flexibly deformed so as to project rearward in a plan view, and therefore, the fitting property is improved. And has excellent cushioning properties.

When the slit 58 is provided in the portion of the backrest plate 21 against which the roller 57 abuts as in the present embodiment, the backrest plate 21 can be easily bent and the lumbar support function can be improved. In this case, since the slit 58 is formed in a step shape and the step difference is supported by the roller 57,
The backrest plate 2 which is provided with the slit 58
It is possible to prevent the backrest plate 21 from being pushed out by the roller 57 and to push out the backrest plate 21 accurately.

(5). Advantages of the embodiment When the horizontal ribs 27 or the horizontal pieces 33 are provided on at least one of the back cover 22 and the backrest plate 21 as in the present embodiment, objects fall inside. There is an advantage that can be prevented.

Further, the cutout portions 38a of the left and right vertical ribs 38
Extends in a range in which the horizontal end 49b of the handle 49 moves up and down so that the vertical rib 38 does not interfere with the horizontal end 49b of the handle 49. With this, handle 4
The backrest plate 21 without impairing the vertical movement operation function of 9.
It is possible to prevent the space between the back cover 22 and the back cover 22 from being excessively exposed to the outside, thereby improving the appearance and ensuring safety.

As can be easily understood from FIG. 18, when the roller 57 is attached to the pressing arm 47, the boss 64 is forcibly fitted into the constricted holes 63 formed in the left and right side plates of the pressing arm 47. Therefore, the roller 57
Can be attached with one touch.

It is not always necessary to provide the roller 57, and the pressing arm 47 may simply be applied to the backrest plate 21, but the use of the roller 47 has an advantage that the vertical height can be adjusted smoothly.

(6). Others The present invention can be embodied in various ways other than the above embodiment.
For example, the back frame 20 can adopt various forms / structures, for example, the whole can be made of sheet metal. The back frame 20 and the swing handle may be integrated.

The back cover and the backrest plate can be variously embodied according to the needs of design and the like. When the lumbar support mechanism is provided, the structure thereof is not limited to that shown in the drawing, and can be embodied in various ways, for example, by providing a handle only on one side.

In the illustrated embodiment, the backrest plate is attached to the back cover and the back frame 20, but the backrest plate may be attached only to the back cover or only the back frame 20. The fact that such selection is possible is one of the advantages of the present invention.

As means for attaching the lower portion of the backrest plate to the back cover or the back frame, the back cover or the back frame is provided with a hook-shaped receiving portion facing upward in a side view, while the backrest plate is fitted to the receiving portion on the back surface thereof. It is also possible to provide a lower mounting portion of a plan view gate type. Of course, other engaging means with play may be provided.

The matters disclosed in the present application including the mounting structure as claimed in claim 5 may be an invention independent from the three-layer structure.

[Brief description of drawings]

FIG. 1 is a right side view of a chair.

FIG. 2 is a front view of a chair.

[FIG. 3] (A) is a rear view of the chair, (B) is a partial rear view of the back cover, and (C) is a sectional view taken along the line CC of (B).

FIG. 4 is an exploded perspective view of a base and an intermediate member.

FIG. 5 is a partial vertical sectional side view.

FIG. 6 is a front view of the backrest with the backrest plate omitted.

FIG. 7 is a vertical sectional side view of a backrest.

FIG. 8 is a vertical cross-sectional side view with a cushion omitted.

9A is a front view of the back frame 20 and a swinging handle separated from each other, and FIG. 9B is a sectional view taken along line BB of FIG. 9A.

FIG. 10 is a sectional view of the backrest on the separated side.

FIG. 11 is a perspective view showing a mounted state of an upper portion of the backrest plate.

FIG. 12 is a perspective view showing a mounted state of a lower portion of the backrest plate.

13A is a schematic plan view of a backrest, and FIG. 13B is a separation plane of a backrest plate and a back cover.

14A is a partial plan view, FIG. 14B is a partial front view, and FIG. 14C is a partial right side view.

FIG. 15 is a front view of a main part of a lumbar support mechanism.

FIG. 16 is a front view of a side edge portion of the backrest plate.

17 is a sectional view taken along line XVII-XVII of FIG. 15.

18 (A) is a sectional view taken along line XVIII-XVIII of FIG. 15, (B) is a sectional view of members, and (C) is a partially cutaway view of (A).

19 is a sectional view taken along line XX-XIX in FIG. 18.

20 is a sectional view taken along line XX-XX of FIG. 18.

21 (A) is a sectional view taken along line XXI-XXI of FIG. 19, and FIG. 21 (B) is a schematic view showing the action.

[Simple explanation of symbols]

5 backrest 7 base 11 rocking frame 20 back frame 20c Lower horizontal member 21 back plate 22 Back cover 25 Lumber support mechanism 28 Downward cylinder 34 Top mounting part 35 Upper receiving part 37 Engaging claw 39 Lower mounting part 39a nail 45 slide case 46 Connection plate 47 Pressing arm 48 interlocking axes 49 handle 55 gears 56 cam 57 Laura

Continued front page    F term (reference) 3B084 EA02 EB05 EC01 EC02 HA04                       HA06                 3B091 AA04 AB04 AC07

Claims (5)

[Claims] 1. A seat and a backrest, wherein the backrest comprises a back frame standing upright behind the seat, a backrest plate (back inner member) arranged on the front side of the backframe, and a backside of the backframe. A chair that has a three-layer structure with the back cover (back outer member) placed in. 2. The back cover is attached to a back frame, while the back plate is attached only to the back frame, only the back cover, or both the back frame and the back cover. Made chair. 3. The chair according to claim 2, wherein a space opened to the outside is vacant between the backrest plate and the back frame. 4. The back cover is fixed to a back frame, while the upper part of the backrest plate is attached to the back cover or the back frame so as not to be movable back and forth and vertically.
The lower part thereof is attached to the back frame or the back cover in such a manner that it cannot move back and forth and can move up and down, thereby allowing the backrest plate to flex and deform. The chair described in one of them. 5. An upper mounting portion which is fitted to a receiving portion provided on a front surface of an upper portion of the back cover from above on a back surface of the upper portion of the backrest plate, and engages with the receiving portion by fitting into the receiving portion. While the engaging claws are provided to hold it in place, the lower surface of the backrest plate is fitted into the space between the horizontal oblong member provided on the back frame and the back cover from above. A lower mounting portion is formed to hold the backrest plate so that it cannot move back and forth and can move up and down.At the lower end of this lower mounting portion, a claw that is hooked from below to the laterally elongated member of the back frame is provided. The chair according to claim 4, wherein a lumbar support mechanism is attached to the back frame to press the backrest plate forward to bend and deform the backrest plate.