JP2003189963A - Chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chair having a synchronized tilting function with small operating physical force while compactifying a system itself. <P>SOLUTION: The chair is provided with a synchronized tilting mechanism ST for tilting a seat back 3 in synchronism with a seat 2 between an erected attitude P and a backward tilted attitude Q, and an elastic member SP interposed between two points with a relative distance changed following tilting and applying force of tilting the seat back 3 and the seat 2 to the erected attitude P side. The elastic member SP is provided with an inner coil spring SPI and an outer coil spring SPO coaxially arranged in an outer side of the inner coil spring SPI. <P>COPYRIGHT: (C)2003,JPO

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 synchro tilt mechanism capable of synchronizing and tilting a backrest and a seat.

[0002]

2. Description of the Related Art Conventionally, chairs having various synchro-tilt mechanisms have been developed, but typically, a support for attaching legs and the like and a base end portion of the support which is tiltably supported. A back frame, a seat in which the front end is slidably and rotatably supported by the support, and a rear end is rotatably supported in the vicinity of the base end of the back frame, and one or parallel seats are arranged under the seat. It is known to have a spring connected so as to be interposed between two points whose relative distance changes with tilting. However, the lever is configured so that even when the backrest fixed to the back frame is tilted, the spring always returns to the standing posture by imparting the tilting force for tilting the backrest and the seat to the standing posture side. .

[0003]

By the way, a chair having a synchro tilt mechanism usually has a large number of parts due to its complicated mechanism, resulting in a large system. In order to prevent this, there is a demand for making each component compact, and of course, it is also strong against the elastic member that constitutes the main part of the synchro tilt mechanism. Therefore, in order to achieve a compact design, this is achieved by changing the spring constant of the spring, but changing the spring constant also has a large effect on the tilting force generated by the spring. The seating comfort is also affected, such as the difficulty of tipping over, and the backrest immediately tipping over when tilting power is small.

Therefore, an operating portion connected to the spring is provided,
By operating this operation part, the length of the spring is changed and the tilting power is changed to adjust the sitting comfort.

However, in the case of the conventional structure as described above, in the case of a single spring, it is difficult to design the spring constant necessary for setting an appropriate tilting power, and the spring constant is large, for example. In that case, the operation becomes difficult,
If it is too small, it will not be possible to maintain a standing posture. On the other hand, if the springs are arranged in parallel, the operation of the springs will be easier than with a single spring, but the system will be easier. There is a problem of getting bigger.

[0006]

In order to solve the above problems, a chair according to the present invention comprises a synchro tilt mechanism for synchronously tilting a backrest and a seat between an upright posture and a rearward leaning posture. An elastic member which is interposed between two points whose relative distances change in accordance with the tilting and which applies a force for tilting the backrest and the seat to the standing posture side, wherein the elastic member comprises:
It is characterized in that it is provided with an inner coil spring and an outer coil spring arranged outside the inner coil spring and on the same axis.

[0007] In such a case, since the two coil springs are arranged on the same axis, there is an effect that the operating force can be reduced while the system itself is compact, and the spring design is a single spring. It has the effect of being easier than.

Further, in order to facilitate the operation, an operating portion and an elastic force adjusting mechanism interposed between the operating portion and the elastic member are further provided, and the elastic force adjusting mechanism operates the operation. It is preferable to change the length of only one of the inner coil spring and the outer coil spring in conjunction with the operation of the section.

Further, in order to realize a more compact chair, the elastic force adjusting mechanism is pushed against one end of the inner coil spring or the outer coil spring to move forward and backward along the direction of expansion and contraction thereof, and the operation. It is sufficient to include a direction changing means for changing the operating direction of the section to the forward / backward direction of the forward / backward member.

As a concrete embodiment thereof, there is provided a support body disposed below the seat, and a back frame having a base end portion rotatably supported by the support body, wherein the elastic member is provided. However, it is conceivable that the back frame is arranged between a portion deviated from the center of rotation of the back frame with respect to the support and a predetermined portion of the support.

In order to realize a compact structure while maintaining the strength of the support, the support has a bottom plate and
The bottom plate is provided with side plates standing up from the respective side edges, and the elastic member is preferably arranged between the side plates.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

The chair according to this embodiment has casters C as shown in the front view and the side view of FIGS. 1 and 2, respectively.
A leg 1 including an attached leg blade 11 and a leg column 12, a seat 2 supported by the leg 1, and a backrest 3 standing upright from the rear of the seat 2 are provided. The backrest 3 and the seat 2 are provided. It has a synchro tilt function that allows it to be synchronized and tilted.

The synchro tilt function in this embodiment means that when the seated person tilts the backrest backward (tilts backward), the seat tilts in conjunction with it.

The structure will be specifically described in detail with reference to FIGS. 3 and 8.

That is, in addition to the leg 1, the seat 2 and the backrest 3 described above, this chair has a support 4 arranged below the seat 1 and a standing posture P (shown in FIG. 3) on the support 4. A back frame 5 having a base end portion 5a supported so as to be tiltable between a rearward tilting posture Q (shown in FIG. 4), and the back frame 5
And a swinging body 6 swingably suspended from a front end portion 5b of the seat 2.
And the rear end portion 2b of the seat 2 is rotatably supported by the oscillating body 6.
A synchro-tilt mechanism ST for fixing the backrest 3 to the backrest 3 and the seat 2 in a synchronized manner between the standing posture P and the backward tilting posture Q, and between the two points whose relative distance changes with the tilting. And an elastic member SP for providing a tilting force for tilting the backrest 3 and the seat 2 to the upright posture side, an operation section SS for adjusting the tilting force, and between the operation section and the elastic member SP. And an elastic force adjusting mechanism 9 that adjusts the elastic force of the elastic member SP in conjunction with the operation of the operation section SS. The seat 2 and the backrest 3 shown in FIGS.
Are simplified and schematically shown.

Explaining each part in detail, the support 4 includes a bottom plate 41 and the bottom plate 4 as shown in FIGS.
1. A rear end portion 4b of the bottom plate 41, which is made of a metal plate having side plates 42 that are integrally bent and erected from the side edges of the bottom plate 41.
The upper ends of the leg columns 12 are attached to the leg columns 12 and are supported by the leg columns 12. The support 4 is covered with a lower cover 43 from below so that it cannot be directly viewed.

As shown in FIG. 3, FIG. 6 and FIG. 8, the back frame 5 is viewed from the side, rearward and upward, from the base end 5a, that is, in the present embodiment, the most forward and lowermost portion in the standing posture. The pair of frame elements 51 are formed so as to extend while curving, and the distal end portion 5b substantially reaches the height corresponding to the lumbar vertebra of the seated person. And a connecting plate 52 for connecting them horizontally. Then, a back frame rotation shaft extending in the horizontal direction is provided in the back frame rotation shaft hole 53 provided in the base end portion 5a of each frame element 51 and the back frame rotation shaft hole 44 provided in the side plate of the support body 4. The back frame is rotatably supported by the support 4 by penetrating R1. Here, "only rotation is possible" includes some rattling necessary for design or assembly. In the present embodiment, the base end portions 5a of the frame elements 51 are set to be located inside the side plates 42 of the support body 4.

The oscillating body 6 is composed of a pair of oscillating elements 61 in the form of a vertical plate which are separated from each other in the left-right direction. Oscillator rotating shaft hole 5 at the tip 5b of each frame element 51
7, the oscillating body rotating shaft R2 extending horizontally from right to left is penetrated,
The back frame 5 is suspended from the tip 5b of the back frame 5 so that it can only rotate about its upper end. Here, “suspend” means that the center of rotation of the rocking body 6 with respect to the back frame 5 is positioned above the tip 5b, which is the rotation end thereof. In addition, in the present embodiment, the upper end portion of each swing element 61 is
It is set so as to be located inside each frame element 51.

As shown in FIGS. 3 and 8, the seat 2 is provided with a rib RB on the inner surface thereof, and a seat outer shell 2 made of synthetic resin having rigidity added to at least support the load of the seated person.
1, a seat inner shell 22 elastically engaged with and fixed to the seat outer shell 21, a seat cushion 23 attached to the upper surface of the seat inner shell 22, and a seat cushion 23 that covers the seat cushion 23 from above. The seat cover 24 forms a seat surface for supporting the buttocks and thighs of the seated person, and as described above, the front end portion 2a thereof.
Is rotatably supported by the support body 4 and the rear end 2b is rotatably supported by the swing body 6.

More specifically, this seat outer shell 21
A front bearing portion 25 and a rear bearing portion 26 are provided at the front end portion of the lower surface and the rear end portion of the lower surface, respectively. Then, the front bearing portion 2
5, the seat front rotation shaft hole 27 and the support 4
The seat front part rotary shaft R4 extending horizontally in the left and right is fitted into the seat front part rotary shaft hole 45 provided at the front end part of the rear bearing part 26.
The rear seat rotation shaft hole 28 and the rocking body 6 provided in the
The seat rear part rotation shaft R3 extending horizontally in the left and right direction is fitted into the seat rear part rotation shaft hole 63 provided in the seat so that the seat 2 is supported by the support body 4 and the swing body 6.

As shown in FIGS. 3 and 8, etc., the backrest 3 has a cushion support member 31 made of synthetic resin having a rigidity sufficient to receive and support a load of a seated person, and an elastic member attached to the cushion support member 31. A back outer shell 32 which is assembled and fixed to the back, a back cushion 33 attached to the front surface of the cushion support member 31, and a backrest surface which covers the back cushion 33 from the front and supports the back of a seated person. And the back cover 34, which is fixed to the rocking body 6 so as to be capable of synchronous tilting as described above.

More specifically, a metal plate-shaped backrest mounting member 35 which is substantially parallel to the backrest surface extends integrally upward from the upper end portion 6a of the rocking body 6, and the cushion support member 31 is provided. The backrest mounting member 35 is screwed at one or more positions on the front surface.

In the present embodiment, the back outer shell 32 extends below the cushion support member 31 so as to cover the back frame 5, the rocking body 6, and the rear end 4b of the support body 4 in an unappealing manner. It is a thing. Also,
The groove 3a provided at the center of the lower end portion thereof is for covering the backrest 3 even if the relative position between the support 4 and the back frame 5 changes as the backrest 3 tilts. is there.

The synchro tilt mechanism ST includes a support body 4, a back frame 5, an oscillating body 6, as shown in FIGS.
The four-sided link mechanism formed by rotatably connecting the seats 2 to each other is realized by the action of tilting the backrest 3 and the seat 2 between the upright posture P and the rearward leaning posture Q in synchronization with each other.

The elastic member SP is shown in FIGS. 8 and 10-12.
As shown in FIG. 1 and the like, it comprises an inner coil spring SPI in which an iron wire is spirally wound, and an outer coil spring SPO in which the iron wire is spirally wound outside the inner coil spring SPI. That is, one end thereof is supported by the protrusion of the connecting member M1 described later, and the other end is supported by the protrusion of the guide member M2 of the elastic force adjusting mechanism 9 described later.

More specifically, the inner coil spring SPI is
The inner end of the connecting member M1 is inscribed and supported by the first projecting portion M11 so that the end of the connecting member M1 is pressed against the first flat surface portion M13 of the connecting member M1 and the other end of the connecting member M1 is connected to the guide member. Between the connecting member M1 and the guide member M2, the end is pressed against the first flat surface portion M23 of the guide member M2 while being supported by being inscribed on the inside by the first projecting portion M21 of M2. It is arranged so as to be sandwiched between.

The outer coil spring SPO has its one end pressed against the second flat surface M14 of the connecting member M1 while having its one end supported by the second protrusion M12 of the connecting member M1 inwardly contacting the inside thereof. The other end is supported by the second protrusion M22 of the guide member M2 with its inner side being inscribed, and its end is pressed against a pressing surface 910a of the advancing / retreating member 91 described below. Connecting member M
1 and the pressing surface 910a of the advancing / retreating member 91 are arranged coaxially with the inner coil spring SPI.

The connecting member M1 is an outer coil spring SP.
A cylindrical second projecting portion M12 that projects so as to support O from the inside thereof, and a second projecting portion M12 that further projects in the direction in which the spring contracts so as to support the inner coil spring SPI from the inside thereof. A cylindrical first protrusion M11,
The peripheral edge of the tip of the second protrusion M12 and the first protrusion M
A first flat surface portion M13 forming a flat surface with the peripheral edge of the base end edge of 11
A second plane portion M14 standing upright from the peripheral edge of the base end of the second protrusion M12, and a hook MF on the side opposite to the protrusion of the second protrusion M12.
By using F, the connecting member M1 is provided on both side plates 42 of the support body 4.
It is connected to a synchro tilt fulcrum shaft 47 which is laterally bridged between them.

The operation portion SS has a grip SSG operated by a user on the base end side and the grip SSG on the tip end side.
A threaded portion SSN extending from the central axis of the SG is provided, and the grip SSG is provided on the support body 4 downward.
While the screw part SSN is arranged so as to project and the inside thereof is located above, the screw part SSN is attached by a suitable structure using a washer SSW or the like so as to be rotatable and not to move in the axial direction.

The elastic force adjusting mechanism 9 presses one end of the elastic force adjusting mechanism 9 against the outer coil spring SPO while the outer coil spring SPO is being pressed.
Is provided with an advancing / retreating member 91 for advancing / retreating in the direction of expansion / contraction, and a direction converting means 92 for converting the operation direction of the operation section SS into the advancing / retreating direction of the advancing / retreating member 91. , A direction changing member 921 having one end abutting against the advancing / retreating member 91 and the other end connected to the operating portion SS, and the advancing / retreating direction of the advancing / retreating member 91 extending / contracting the elastic member SP while supporting the elastic member SP. A guide member M2 for guiding in a direction, and a support member M3 for disposing a part of the direction changing member 921, the guide member M2, and the operation portion SS therein are provided. In addition, the “operation direction” in the present embodiment indicates the direction in which the direction changing member 921 moves forward and backward in the axial direction of the screw part SSN by the operation of the operation part SS.

More specifically, the advancing / retreating member 91 has a pressing surface 910a which is directly pressed against the outer coil spring SPO and a thin disk shape having the pressing surface 910a on one side, and the second projecting portion M22 of the guide member M2 is centered. Through hole 9 inscribed by
10b is provided, and an advancing / retreating auxiliary portion 911 forming a pair having a rectangular cross section extending from both sides of the peripheral edge of the ring plate portion 910 toward the direction changing surface 921a of the direction changing member 921. The advancing / retreating auxiliary portion 911 further has a contact surface 9 having a downward slanting angle for contacting the direction changing surface 921a of the direction changing member 921.
11a is provided at its tip. Then, since the pressing surface 910a is pressed against one end of the outer coil spring SPO on the operation portion SS side,
The contact surface 911a of the advancing / retreating auxiliary portion 911 is always pressed against the direction changing surface 921a of the direction changing member 921.

The direction changing member 921 has the screw portion SSN.
And a guide member M
Provided so as to form a pair on both sides of the screw attachment portion 922 having a second abutment surface 922b that abuts on the second attachment surface 922b and to incline upward with respect to the operation direction of the operation portion SS. And the direction changing member 92 is operated by operating the operation section SS.
When the second contact surface 922b of No. 1 moves vertically while being guided by the contact guide surface M24 of the guide member M2, the direction changing surface 921a moves back and forth in the expansion and contraction direction of the elastic member SP. The advancing and retracting member 91 is advanced and retracted in the advancing and retracting direction while contacting the pressing surface 911a.

The guide member M2 has a cylindrical second projecting portion M22 projecting so as to support the outer coil spring SPO from the inside thereof and a coaxial second projecting portion M22 so as to support the inner coil spring SPI from the inside thereof. A first projecting portion M21 having a cylindrical shape that further projects in the direction of contraction of the spring, and a flat surface between the tip edge peripheral edge of the second projecting portion M22 and the base end edge peripheral edge of the first projecting portion M21. One plane portion M23, a second plane portion M24 standing upright from the peripheral edge of the base of the second protrusion M22, and a pair of guides for advancing and retracting the advancing / retreating member 91 while forming a pair on both sides of the second protrusion M22. A guide portion M23 provided with a guide opening hole M23a having a rectangular cross section and a planar shape that abuts the second contact surface 922b of the direction changing member 921 in the opposite direction in which the second protrusion M22 projects. Contact guide surface M It is intended to and a 4.

The support member M3 is formed by bending a thin sheet metal into a U shape so that the opening faces downward and is blocked by the bottom plate of the support 4 and bridges both side plates 42 of the bottom plate 41. The opening window M32a, which is attached to the tip of the elastic member side plate M31, has the upper surface M32 through which the direction changing member 921 can be inserted.
Second opening window M3 through which the advancing / retreating auxiliary section 911 of
1b and.

This operation will be specifically described below.

As described above, the synchro tilt function has the support member 4, the back frame 5, and the swing member 6 as described above.
This is realized by the action of the four-sided link mechanism formed by connecting the seat 2 and the seat 2 rotatably to each other, and making them have a function as a link member. In the present embodiment, this four-sided link mechanism is as follows. Is configured.

That is, the center of the back frame rotation axis R1 which is the connecting axis between the support 4 and the back frame 5 is X.
1. X2 is the axis center of the rocking body rotating shaft R2 that is the connecting shaft between the back frame 5 and the rocking body 6, and X2 is the axis center of the seat rear rotating shaft R3 that is the connecting shaft between the rocking body 6 and the seat outer shell 21.
3, when the axial center of the seat front rotation axis R4, which is the connecting axis between the seat outer shell 21 and the support body 4, is X4, in the present embodiment, these axial centers X1 to X4 are X in a side view and from the front.
4, X1, X3, X2 are arranged in this order,
X2 is located above the straight line L1 connecting X4 and X1, and X3 is located below the straight line L2 connecting X4 and X2.

By doing so, when the back frame 5 is tilted from the standing posture shown in FIG. 3 toward the rearward leaning posture shown in FIG. 4, X2 rotates backward around X1 and downward and X4. It will move away from. As a result, the distance between X4 and X2 becomes longer, and the seat outer shell 21, which is a link connecting X4 and X2, and the oscillating body 6 move so that the angle they make becomes larger. In other words, these move so that the oscillating body 4, that is, the back tilt angle of the backrest 3, is larger than the back tilt angle of the seat outer shell 21 that occurs in response to the rearward tilting of the back frame 5. Since the front end of the seat 2 is located in front of the connection point with the support body 4, the front end of the seat 2 slightly rises in this embodiment as the seat 2 tilts backward.

Further, in this embodiment, X1 and X2
X3 is positioned below the straight line L3 connecting the lines.

By doing so, similarly to the above, when the back frame 5 is tilted rearward from the standing posture, X3 rotates downward around X4 and moves toward X1. As a result, the distance between X1 and X3 is shortened, and the back frame 5 and the oscillating body 6, which are the links connecting X1 and X3, move so that the angle they make becomes larger. In other words, back frame 5
These move so that the oscillating body 6, that is, the back tilt angle of the backrest 3, is larger than the back tilt angle.

The following mechanism is provided in this embodiment in order to regulate the range of tilting of the back frame 5 in the front-rear direction. That is, as shown in FIG. 3 and the like, the stopper member 5 having a downward surface is provided at an intermediate portion of the back frame 5.
4 is provided, and the stopper member 54 is brought into contact with the upward surface 46 provided on the rear portion of the support body 4 so as to restrict the further backward tilting operation. Further, from the back frame 5, the stopper shaft 56 is projected to the left and right at a portion deviated from the center of rotation X1, while each side plate of the support body 4 is provided with an elongated hole 55 having a partial arc shape, and the stopper is provided. The left and right ends of the shaft 56 are fitted in these elongated holes 55, respectively. Then, the stopper shaft 56 is brought into contact with the front end of the elongated hole 55 so that the further forward tilting movement of the back frame 5 is restricted.

Therefore, according to the chair of this embodiment having the above-described structure, the backrest 3 and the seat 2 are synchronized and tilted, and moreover, the rocking body generated by the tilting of the back frame 5 with respect to the tilting angle thereof is increased. It is possible to reasonably increase the tilt angle, that is, increase the tilt angle of the backrest 3.

When the backrest 3 and the seat 2 assume the rearwardly tilted posture Q with a large tilting angle, the elastic member SP acts on the synchro-tilt mechanism ST to impart a force for tilting it to the standing posture P side.

Specifically, when the chair is in the rearwardly tilted posture Q, the inner coil spring SPI and the outer coil spring SPO forming the elastic member SP are attached to the synchro tilt acting shaft 47 and the support 4 inside. The member is placed in a state of being contracted with the member M3 more than in the standing posture P, and a restoring force for restoring the original length is generated.

Since this restoring force acts on the synchro tilt acting shaft 47 which is deviated from the back frame rotating shaft R1 which is the center of rotation of the back frame 2 with respect to the support 4, the back frame rotating shaft R1 is moved. As a fulcrum, a tilting force that tilts the backrest 3 and the seat 2 toward the standing posture P is generated.

At this time, when the tilting power is large and the backrest does not easily fall down, or when the tilting power is small and the backrest tilts down quickly, the tilting power is adjusted by operating the operation section SS.

When the grip SSG of the operation portion SS is rotated in the tightening direction of the screw, the screw SSN connected to the grip also rotates in the same direction. The direction changing member 921 attached to the screw SSN moves toward the tip of the screw SSN and pushes up the contact surface 911a of the advancing / retreating member 91 with which the direction changing surface 921a is in contact. Then, the advancing / retreating member 9 inserted into the guide opening hole M23a of the guide member M2.
The forward / backward assisting portion 911 of No. 1 is guided by the guide member M2, and the forward / backward member 91 moves forward / backward in the direction of contracting the outer coil spring SPO, which is a direction substantially perpendicular to the operating direction. The outer coil spring SPO pressed against the pressing surface 910a is compressed.

When the outer coil spring SPO is contracted by the advancing / retreating member 91 and a large restoring force is generated in the outer coil spring SPO, this restoring force is applied to the inner coil spring SP.
Along with the restoring force of I, a large restoring force is obtained to act so as to push the synchro tilt acting shaft 47.

At this time, the synchro tilt acting shaft 47 is located at a position displaced from the back frame rotating shaft R1 which is the center of rotation of the back frame 5 with respect to the support 4, and when the restoring force acts on this, the support 4 is supported. Begins to work as a tilting force that rotates about the back frame rotation axis R1, and while the seat 2 connected to the support 4 and the back frame 5 and the swinging body 6 are synchronized, the chair is driven by a large tilting force. Comes to take a standing posture P.

That is, by rotating the grip of the operation portion SS in the direction in which the screw is tightened, the tilting power for erecting the chair can be strengthened.

On the other hand, when the grip of the operation portion SS is turned in the direction in which the screw loosens, the screw SSN connected thereto also rotates in the same direction. The direction changing member 921 attached to the screw SSN moves to the base end side of the screw SSN,
The direction conversion surface 921a moves away from the contact surface 911a of the advancing / retreating member 91 with which the direction conversion surface 921a is in contact. Then, the outer coil spring SPO pushes the advancing / retreating member 91 back toward the operation portion SS by the restoring force, but at this time, the advancing / retreating auxiliary portion 911 of the advancing / retreating member 91 causes the guide opening hole M23 of the guide member M2.
The guide member M2 guides the advancing / retreating member 91 while keeping the state where the contact surface 911a of the advancing / retreating member 91 is pressed against the direction changing surface 921a of the direction changing member 921. Is moved in the direction of extension.

In this way, the advancing / retreating member 91 extends the outer coil spring SPO, and the restoring force of the outer coil spring SPO becomes smaller. This restoring force is the inner coil spring SPO.
Along with the restoring force of PI, a small restoring force, that is, a weak force acts to push the synchro tilt action shaft 47.

Then, the synchro tilt acting shaft 47 starts to act as a tilting force to rotate about the back frame rotation axis R1 with respect to the support body 4, and is connected to the support body 4, as described above. While the seat 2 and the back frame 5 and the rocking body 6 are synchronized, the chair takes the standing posture P by a small tilting force.

That is, by rotating the grip of the operation portion SS in the direction in which the screw is loosened, the tilting power for raising the chair can be weakened.

As described above, the screw S is provided on the operation portion SS.
Simply by operating in the direction of turning SN, the tilting force can be adjusted with a small operating force, and two coil springs are arranged on the same axis, or a direction changing means for converting the operating direction into a substantially right-angled direction. Since the elastic force adjusting mechanism 9 is provided with 92, the system itself can be made compact.

Further, since the inner coil spring SPI bears the main tilting force and the tilting force can be adjusted by operating only the outer coil spring SPO, the design of the adjusting silo becomes easier, and the conventional single spring or parallel spring is used. It is possible to provide a chair that has an effect that the burden on the design is less than that of the product and that the product is comfortable to sit on.

The present invention is not limited to the above embodiment.

Specifically, the elastic member SP that expands and contracts by operating the operation portion SS is only the inner coil spring SPI, but the invention is not limited to this, and only the outer coil spring SPO may expand and contract.

Further, various shapes and materials of the respective parts such as the back frame, the support, the rocking body and the like can of course be considered in addition to the above embodiment.

For example, as shown in FIG. 9, the same effect can be obtained by applying the present invention to a chair in which the back side of the seat and the backrest are integrated and the front side of the seat is separated.

Concretely, this is composed of a support 4, a back frame 5 supported by the support 4 so as to be tiltable between a standing posture and a rearward posture, and a tip portion 5b of the back frame 5. A front end portion 71 of a front seat body 7 that forms the front side of the seat and is rotatably connected to the support body 4 and a rear end of the front seat body 7. While the portion 72 is rotatably connected to the rocking body 4, a back seat body 8 integrally forming a backrest and a seat back side is integrated with or attached to the rocking body 6. The operation of the synchro tilt mechanism ST, the operation of the elastic member SP, and the like are the same as those in the above-described embodiment, and thus the description thereof is omitted. Further, the same reference numerals are given to the members corresponding to the above-mentioned embodiment.

Further, in the above embodiment, the lower end of the backrest 3 is separated from the rear end of the seat 2, but the lower end of the backrest 3 and the rear end of the seat 2 are brought close to or in close contact with each other, and The moving body 6 and the seat 2 may be positioned near the connecting point. With this arrangement, the lower end of the backrest 3 and the rear end of the seat 2 do not largely separate from each other and move in a continuous relationship despite the tilting motion.

Others The present invention is not limited to the illustrated examples described above, and various modifications are possible.

[0065]

As described in detail above, according to the present invention,
Since the two coil springs are arranged on the same axis,
It is possible to provide a chair in which the system itself is compact, the operation is simple and the operation force is small, and the spring design is simpler than that of a single spring.

[Brief description of drawings]

FIG. 1 is a front view of a chair according to an embodiment of the present invention.

FIG. 2 is a side view of the chair according to the same embodiment.

FIG. 3 is an operation explanatory view seen from the side for explaining the operation of the chair in the same embodiment.

FIG. 4 is an operation explanatory view seen from the side for explaining the operation of the chair in the same embodiment.

FIG. 5 is a side view of a support according to the same embodiment.

FIG. 6 is a side view of the back frame in the same embodiment.

FIG. 7 is a side view of the oscillator according to the same embodiment.

FIG. 8 is an exploded perspective view of the chair according to the same embodiment.

FIG. 9 is a schematic side view of a chair according to another embodiment of the present invention.

FIG. 10 is an exploded perspective view of the elastic member according to the embodiment of the present invention.

FIG. 11 is an operation explanatory view seen from the side for explaining the operation of the elastic member in the same embodiment.

FIG. 12 is an operation explanatory view seen from the side for explaining the operation of the elastic member in the same embodiment.

[Explanation of symbols]

2 ... 3 ... back 4 ... Support 41 ... Bottom plate 42 ... Side plate 47 ... Synchro tilt action axis 5 ... Back frame 9 ... Elastic force adjustment mechanism 91 ... Advancement / retraction member 92 ... Direction changing means P: Standing posture Q: Backward tilt R1 ... Back frame rotation axis SS: Operation part ST: Synchro tilt mechanism SP: Elastic member SPI: Inner coil spring SPO: Outer coil spring

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Fumihiro Kurata             5331 Takaharu Shimogawara, Nishiharu near Ina City, Nagano Prefecture             Inside the furniture development department (72) Inventor Yojiro Kinoshita             6-1, 1-1 Minami Oimazato, Higashinari-ku, Osaka             Kuyo Co., Ltd. (72) Inventor Taiki Fukuda             6-1, 1-1 Minami Oimazato, Higashinari-ku, Osaka             Kuyo Co., Ltd. F-term (reference) 3B099 AA02 BA09 CA01 CA36

Claims (5)

[Claims] 1. A synchro-tilt mechanism for synchronously tilting a backrest and a seat between an upright posture and a rearward leaning posture, and a synchro-tilt mechanism interposed between two points whose relative distances change in accordance with the tilting. And an elastic member for imparting a force for tilting the elastic member to the standing posture side, wherein the elastic member is an inner coil spring,
A chair provided with an outer coil spring arranged outside the inner coil spring on the same axis. 2. An operating portion, and an elastic force adjusting mechanism interposed between the operating portion and the elastic member, wherein the elastic force adjusting mechanism is interlocked with an operation of the operating portion, and the inner coil spring or the outer coil spring is provided. The chair according to claim 1, wherein the length of only one of the coil springs is changed. 3. An elastic member adjusting mechanism, which is pressed against one end of the inner coil spring or the outer coil spring to move forward and backward along the expansion and contraction direction of the elastic member, and an operation direction of the operation section, the forward and backward directions of the forward and backward members. The chair according to claim 2, further comprising: 4. A support body disposed below a seat, and a back frame rotatably supporting a base end portion of the support body, wherein the elastic member is provided on the back frame. 4. The chair according to claim 1, wherein the chair is arranged between a portion deviated from the center of rotation with respect to the support and a predetermined portion of the support. 5. The support body comprises a bottom plate and side plates standing upright from respective side edges of the bottom plate, wherein the elastic member is arranged between the side plates. The chair according to claim 4.