JP4697894B2 - Chair - Google Patents

Description

  The present invention relates to a chair having a backrest.

  There are various types of chairs, and various improvements are made according to each type. As an example, for example, Patent Document 1 discloses a chair in which the seat tilts forward when a seated person leans against the backrest, while Patent Document 2 discloses that the seat is positioned at a substantially middle portion before and after the seated person. There is described a chair that tilts in side view around the center and that the backrest tilts in conjunction with the rear tilting of the seat. Both patent documents employ a kind of link mechanism as means for interlocking the backrest with the seat.

  In the case of Patent Document 1, the posture of the seat and the backrest is not changed only by the person sitting, and when the seated person leans on the backrest and a large moment is applied to the backrest, the rear part of the seat is pushed upward by the lever principle. It is intended to tilt the seat forward, and its purpose is to ensure a comfortable state by making it easier to stretch the human body in the locked state.

On the other hand, in Patent Document 2, for example, when a person sits on the front part of the seat, the backrest greatly tilts forward and pushes the person forward, and the user feels uncomfortable and shifts the sitting position backward. It will be. That is, in Patent Document 2, a so-called “chung” (or choi) on which a user sits on the front part of a seat gives discomfort, thereby allowing a correct sitting posture to be taken.
Japanese Examined Patent Publication No. 44-20784 Japanese Examined Patent Publication No.46-27517

  When a person uses a chair, he does not necessarily sit deeply, but often sits shallowly. Since the use of chairs varies from person to person, the design philosophy of the chair also requires a user-friendly idea to minimize the burden on the user even if the sitting position is different (such as in offices). It is often necessary to sit shallowly in business, so there is a high need to consider such usage.)

  However, the thing of patent document 1 is only assumed that it is in a rocking state, and no consideration is given to what is called a shallow sitting. On the other hand, the thing of patent document 2 is trying to make the user put on the heel which sits down deeply, and it is hard to say that this also considers a user enough.

  Furthermore, in order to reduce the burden on the body of a person who has been seated, it is important to support the person's waist and make it easier to take a state where the back is stretched. A chair with a lumbar support that supports it in a concentrated manner is prevalent, but since the one in Patent Document 2 tilts the entire backrest forward, the user of the chair is pushed by the backrest at the top of the backrest. As a result, the spine is not stretched, and therefore the lumbar support function cannot be ensured in Patent Document 2.

  Furthermore, the configuration of Patent Document 2 has a problem that when a person sits shallowly, the seat is inclined forward, and it is difficult for the person to take an upright posture with the upper body extended.

  This invention is made | formed in view of such the present condition, and makes it a subject to provide a more user-friendly chair.

The chair according to the invention of claim 1 is provided with “a seat and a backrest, and the backrest is provided with a lumbar support portion against which a waist of a seated person hits, while the seat is retracted while being lowered. is attached to the seat receiving member to slide in the slide means, the seat receiving member is biased by a spring in a direction to advance and elevated, the seat while down against the spring and human sits It has become the basic configuration that be that "retreat.
Further, in the present invention, the slide means comprises a fixed guide shaft that has a forward tilt posture with a high front and a low back, and an outer cylinder that is slidably fitted on the guide shaft. The outer cylinder includes a spring that urges the outer cylinder in a direction that moves upward while moving forward.

A chair according to a second aspect of the present invention is the chair according to the first aspect, wherein the slide means includes a rail inclined so that the front is high and the back is low in a side view, and a slide disposed behind the rail. The rail is provided on the base, and the seat receiving member slides along the rail, while the slide link is rotatably connected to the seat receiving member and the base. ing.
In addition to the same basic structure as in claim 1 , the chair according to the invention of claim 3 is provided with interlocking means for advancing at least the lumbar support portion of the backrest by lowering and retreating the seat. And in invention of Claim 3, while the said backrest is attached to the back frame which can be tilted back, the said interlocking means has the link for interlocking connected with the said back frame so that rotation is possible, When the seat moves backward while descending, the interlocking link rotates without the back frame tilting backward.

  In the chair of the present invention, when the person is seated, the seat moves backward, so that even if the person sits shallowly on the seat, the seated person's waist can be supported from behind with the backrest. That is, the backrest can exhibit a lumbar support function, and therefore, the burden on the user's body can be significantly reduced even in a shallow sitting state.

Further, since the seat slides without changing the posture in side view, the user can take a posture in which the spine is extended. This is another feature of the present invention. According to the third aspect of the present invention, since the seat back moves in addition to the backrest moving forward by the seating, it is possible to more reliably support the human waist by the lumbar support portion by the seating.

  Next, embodiments of the present invention will be described with reference to the drawings. First, reference examples will be described prior to description of the embodiments. Both the reference example and the embodiment are applied to a rotary chair for office use.

(1). Structure of First Reference Example FIGS. 1 to 5 show a first reference example. 1A is a side view of the chair, FIG. 2B is a perspective view of the back inner shell, FIG. 2A is a separated side view of the main member, and FIG. 1B is a backrest attached state. 3 is a partially broken perspective view, FIG. 3 is a schematic separated front view of a main member partially broken, FIG. 4 is a sectional view taken along line VV in FIG. 1, and FIG. 5 is a side view showing movement.

  The chair includes a leg support 1 made of a gas cylinder, a seat receiving base 2 fixed to the upper end thereof, an intermediate member 3 attached to the seat receiving base 2, a seat 4 attached to the intermediate member 3, and a seat receiving base 2. Two left and right back frames 5 connected so as to be tiltable rearwardly and a backrest 6 supported by the back frame 5 are provided.

  The backrest 6 includes a back inner shell 7 schematically shown in FIG. 1 (B), and a cushion material 8 is stretched on the front surface of the back inner shell 7 as clearly shown in FIG. 2 (B). Although not shown in the drawings, the leg support 1 is attached to a leg base having a plurality of branch branches extending radially, and each branch branch is provided with a caster.

  The seat base 2 is formed in a box shape opened upward, and the intermediate member 3 is connected to the front portion thereof by a first shaft 11 that is long in the left-right direction. The intermediate member 3 is formed in an open U shape in a front view (see FIG. 3), and the first shaft 11 passes through the side plate 3 a and the seat receiving base 2. The insertion hole of the first shaft 11 in the seat receiving base 2 is a long hole 12 extending rearwardly in a side view, so that the first shaft 11 can slide along the long hole 12. A resin bush 13 is mounted in the long hole 12.

  The back frame 5 is composed of an arm portion 5a that is inclined rearward when viewed from the side and a back column 5b that extends substantially vertically, and has a generally square shape when viewed from the side. The distal end portion of the arm portion 5 a and the front and rear halfway portion of the seat receiving base 2 are connected by the second shaft 13. Further, the rear part of the intermediate member 3 and the front / rear halfway part of the arm part 5a are connected by a third shaft 13 'which is long in the left-right direction. Therefore, the intermediate member 3 and the back frame 5 move backward while tilting in conjunction with each other. Although not shown, a spring that supports the backward movement of the first shaft 11 is disposed inside the seat receiving base 2, and the backrest 6 is locked against this spring.

  The seat 4 has a structure in which a cushion 4b is stretched on the upper surface of a seat inner shell 4a made of resin or the like. Then, a U-shaped bracket 14 having a width substantially the same as that of the intermediate member 3 and opened downward is fixed to the lower surface of the seat 4, and the left and right side plates of the bracket 14 and the intermediate member 3 are paired in front and rear pairs. 15 are connected by a parallel link mechanism.

  Each first link 15 is located outside the bracket 14 and the intermediate member 3, the lower end of the front first link 15 is connected to the intermediate member 3 by the first shaft 11, and the rear first link 15. Is connected to the intermediate member 3 by a dedicated shaft 16. A shaft connecting the first link 15 to the bracket 14 is indicated by reference numeral 17. In the non-sitting state (neutral state), the first link 15 is slightly tilted backward as viewed from the side. This is because the first link 15 is tilted backward by seating. Although not shown, a stopper that prevents the first link 15 from tilting forward is provided.

  By connecting the seat 4 and the intermediate member 3 with the parallel link mechanism, the seat 4 can be lowered and lowered without changing the posture in side view. In other words, the seat 4 does not tilt forward or backward, and can move backward while descending while maintaining a substantially horizontal posture. The first link 15 may be connected to a downward protrusion integrally formed with the inner shell 4a of the seat 4. Needless to say, the means for lowering and retracting the seat 4 is not limited to the parallel link mechanism.

  The upper portion 5b 'of the back column portion 5b in the back frame 5 is separated from the lower portion thereof and is connected to the lower portion via a coil spring 18. For this reason, the upper end portion 5 b ′ of the back column portion 5 b can tilt backward against the elasticity of the coil spring 18.

  The backrest 6 is attached to the upper end portion 5b 'of the back column portion 5b in the back frame 5 at a portion of the back surface that is somewhat below the upper end, and its specific structure is shown in FIG. 2 (B). . That is, a crosspiece 19 having a laterally long and inwardly U-shaped cross section is fixed to the upper end portion 5b 'of the left and right back struts 5b by welding or the like. 20 is integrally formed, and the protruding piece 20 is fastened to the crosspiece member 19 with screws (bolts) 21.

  In this case, as a feature of the present reference example, a vertically long tongue-like piece 22 surrounded by a slit 22a opened upward in the back inner shell 7 is formed, and a protruding piece 20 is formed at the lower end of the tongue-like piece 2. ing. For this reason, when the tongue-like piece 22 is deformed so as to bend, the backrest 6 tilts around the root of the tongue-like piece 22 and the backrest 6 moves to the front side of the back column part 5b as a whole. And are allowed. The protruding piece 20 may be formed of a member different from the back inner shell 7.

  The backrest 6 includes a lumbar support portion (lumbar support portion) 6a that hits a portion centered on the waist of the person who is seated. The lumbar support portion 6a is curved in a forwardly convex shape in a side view, and the lumbar support portion 6a moves back and forth when the backrest 6 tilts in a side view with the tongue-like piece 22 as the center. As shown in FIG. 1 (B), the inner shell 7 of the backrest 6 is provided with such flexibility that the shape of the side view and the shape of the plan view can be changed at least at the location of the lumbar support portion 6a. Giving flexibility to the back inner shell 7 can be achieved, for example, by forming a group of slits.

  On the back of the lumbar support portion 6a in the backrest 6, a belt-like push plate 24 that is long in the left-right direction is fixed by screwing or the like.

  Next, the interlocking means will be described. In this reference example, the lumbar support portion 6a of the backrest 6 protrudes forward by utilizing the backward sliding movement of the seat 4, and the interlocking means is connected to the inner surfaces of the left and right back frames 5 by the first connecting shaft 25. The front and rear long second links 26, the left and right third links 28 connected to the push plate 24 of the backrest 6 via the left and right long second connecting shafts 27, the second links 26 and the third links 28, And a pair of left and right gas cylinders 30 that maintain a relative angle between the second link 26 and the fourth link 29. The front end of the third link 28 is connected to a bearing piece 24a (see FIG. 4) formed on the push plate 24, but may be connected to a rearward protruding piece formed on the back inner shell 7.

  The gas cylinder 30 is rotatably connected to the second link 26 and the fourth link 29 by a pin 31. Note that only one gas cylinder 30 may be disposed at the left and right intermediate portions, or three gas cylinders 30 may be disposed at three locations with the left and right intermediate portions of the second link 26.

  The lower end of the fourth link 29 is connected to the second connecting shaft 27, and the rear end of the third link 28 and the upper end of the fourth link 29 are connected by the fourth connecting shaft 32. The second link 26 is formed in a bowl shape with an upward opening, and the lower end portion of the fourth link 29 and the lower end portion of the gas cylinder 30 are located inside the second link 26. Further, since the interval between the left and right third links 28 is wider than the interval between the left and right second links 26, a large interval is provided between the third link 28 and the fourth link 29 as shown in FIG. .

  The front end of the second link 26 is formed with a long slot 33 that opens forward in a side view, and the left and right longitudinal slots fixed to the bracket 14 on the lower surface of the seat 4 via the auxiliary member 14a. The operating shaft 34 is fitted.

(2). Movement and Advantages of First Reference Example In the above configuration, when a person sits on the seat 4, as shown in FIG. 5, the seat 4 moves backward while being lowered by the action of the parallel link mechanism. Then, the second link 26 is rotated to the forward inclined posture by the pressing action of the operating shaft 34, and then the relative angle between the second link 26 and the fourth link 29 is held constant by the gas cylinder 30. The third link 28 is pushed forward, whereby the lumbar support portion 6a of the backrest 6 moves forward greatly. For this reason, even if a person sits shallowly on a chair, the person's waist can be accurately supported and the lumbar support function can be exhibited.

  When a person sits deeply on the chair, the lumbar support portion 6a of the backrest 6 is pushed back by the contraction of the gas cylinder 30, so that it is not obstructed to sit deeply. Moreover, since the lumbar support part 6a of the backrest 6 has flexibility so that the side view shape and the planar shape can be changed, the backrest 6 fits the human body even if the physique of the user is different. For this reason, it is comfortable to sit on. Further, even when the lumbar support portion 6a is deformed, it is not impaired to sit down deeply.

  When the gas cylinder 30 is provided as in this reference example, the lumbar support portion 6a can move back and forth following the movement of the user even if the user moves his / her body back and forth. . In addition, by locking the gas cylinder 30, the initial advance position of the lumbar support portion 6a can be adjusted. An elastic body such as a coil spring can be provided instead of the gas cylinder 30.

  When the seated person leans on the backrest 6, the backrest 6 tilts backward as a whole, and the seat 4 also tilts backward while moving backward. In this case, the portion close to the upper end of the backrest 6 is attached to the back column 5b via the tongue-shaped piece 22, so that when seated, the backrest 6 assumes a rearward tilting posture as a whole. The tilt angle is an angle obtained by adding the angle at which the backrest 6 tilts backward by sitting and the rear tilt angle of the back frame 5. Therefore, comfort in the locked state can be improved.

  Further, the back frame 5 tilts backward in the locked state as shown by a one-dot chain line in FIG. 5, and the backrest 6 is lowered as a whole by the backward tilting of the back frame 5. It is slightly larger than the tilt angle (because the amount of movement increases with increasing distance from the center of rotation of the back frame 5). For this reason, a deep comfort posture can be taken.

  Further, since the backrest 6 tilts backward in a natural posture when seated, the backrest 6 does not receive a feeling of pushing up on the back and waist of the person at the time of rocking, and a comfortable rocking state without a sense of incongruity can be obtained. Further, when the user sits down, the backrest 6 tilts backward, so that the user can lean on the backrest 6 with the upper body tilted backward when the backframe 5 is not tilted backward. As a result, the transition to the locking state is performed very smoothly.

  Further, when the seat 4 is moved downward by locking, the front portion of the second link 26 is pushed downward by the operating shaft 34, so that the backrest 6 moves more downward as compared with the case where the backrest 6 is simply attached to the back frame 5. Therefore, it is possible to prevent a so-called shirt-rolling phenomenon caused by an increase in the relative distance between the seat 4 and the backrest 6.

  When the upper portion of the back column portion 5b is bent against the spring 18 as in this reference example, the cushioning property in the locked state is enhanced, so that the comfort can be further improved.

(3). Second reference example (Figs. 6-7)
6 and 7 show a second reference example. 6 is a side view in a non-sitting state, and FIG. 7 is a partial side view in a sitting state.

  This second reference example is a modification of the first reference example. The difference from the first reference example is that a stopper pin 36 is provided on the first link 15, and that the fourth link 29 and the lumbar support portion 6a are different. The lower end is connected with the fifth link 37, and the attachment positions of the third link 28 and the fifth link 37 with respect to the fourth link 29 are adjustable (the third link 28 and the fifth link 37 include: A plurality of mounting holes 39 for the connecting shafts 32 and 38 are formed.) The operating shaft 34 is attached to a bearing portion 40 formed on the inner shell 4 a of the seat 4.

  In the second reference example, when the stopper pin 36 of the first link 15 hits the upper surface of the intermediate member 3, the downward movement and the backward movement of the seat 4 are restricted. Further, since the fifth link 37 is present, the lumbar support portion 6a is maintained in a shape that is curved forward and convex in a side view, so that the lumbar portion of the seated person can be accurately supported.

  Furthermore, since the attachment positions of the third link 28 and the fifth link 37 with respect to the fourth link 29 can be adjusted, the initial shape and the front-rear position in the side view of the backrest 6 can be changed. The position and profile of the backrest 6 can be set according to the above. In addition, you may enable it to adjust a side posture and back-and-forth position of the backrest 6 steplessly.

(4) Third reference example (Fig. 8)
FIG. 8 shows a third reference example. In this reference example, a seesaw-type sixth link 42 in which upper and lower halfway portions are connected to the left and right side surfaces of the intermediate member 3 by a sixth connection shaft 41 as interlocking means for moving the lumbar support portion forward by lowering and retracting the seat. A seventh link 43 connecting the sixth link 42 and the side surface of the backrest 6, guide members 44 provided on the left and right side surfaces of the seat 4, a lower end of the sixth link 42, and upper and lower middle portions of the seventh link 43 And a gas cylinder 30 connected to each other.

  The guide member 44 has a long hole 45 extending substantially rearwardly. A slide pin (or roller) 46 provided at the upper end of the sixth link 42 is fitted into the long hole 45. Further, the lower end of the seventh link 43, the sixth link 42 and the sixth connecting shaft 41 are connected to the intermediate member 3. Each link is arranged in a pair on the left and right.

  In this reference example, when a person is seated, the sixth link 42 and the seventh link 43 are rotated counterclockwise as viewed from the left side by the pressing action of the guide member 44, thereby causing the backrest 6 to tilt backward and lumbar The support portion 6a moves forward greatly.

(5). First embodiment (FIG. 9)
Next, an embodiment of the present invention will be described with reference to FIG. In each embodiment, the same reference numerals are given to the same components as those in the reference example described above, and the description thereof is omitted.

  FIG. 9 shows a first embodiment of the present invention. (A) is a right side view, (B) is a partial plan sectional view. In this embodiment, as a means for lowering the seat 4 while lowering, the left and right guide shafts 48 are fixed to the intermediate member 3 in the forward tilt posture (ie, the front is high and the back is low) in a side view. The seat receiving member 50 is fixed to an outer cylinder 49 that is slidably fitted to the guide shaft 48, and the seat 4 is fixed to the seat receiving member 50. The outer cylinder 49 incorporates a spring 51 that returns the seat 4 to the neutral state.

Then, a reinforcing bar 52 having a square cross section or the like is fixed to the front surfaces of the left and right back struts 5b by welding or the like, and the front and rear halfway portions of the eighth link 53 as an interlocking link are connected to the left and right end surfaces of the reinforcing bar 52 by an eighth connection. The operating shaft 34 fixed to the side surface of the seat receiving member 50 is fitted in a longitudinally long slot 55 that is connected by the shaft 54 and provided in the front portion of the eighth link 53. Further, the eighth link 53 and the push plate 24 of the backrest 6 are connected by the ninth link 56 and the tenth link 57. The eighth link 53 corresponds to the second link 26 of the first reference example, the ninth link 56 corresponds to the third link 28 of the first reference example, and the tenth link 57 corresponds to the fourth link 29 of the first reference example. It corresponds to.

  When the outer cylinder 49 moves backward diagonally downward against the spring 51, when a person sits on the seat 4, the seat 4 moves backward while descending. Then, similarly to the reference example described above, the lumbar support portion 6a of the backrest 6 moves forward by the interlocking means.

(6). Second embodiment (FIGS. 10 to 11)
FIG. 10 shows a second embodiment. In this embodiment, the seat receiving member 59 is formed in an inverted letter shape in a right side view (a letter shape in a left side view), and an inclined portion 59a of the seat receiving member 59 is used as a means for sliding the seat 4. The rail 60 that is slid rearward and the eleventh link 61 connected to the upper portion of the seat receiving member 59 and the seat receiving base 2 are used in combination. The eleventh link 61 is a slide link.

  The inclined portion 59a of the seat receiving member 59 is inclined so that the front is high and the rear is low. A long hole 62 is formed in the inclined portion 59a, and the guide pin 63 projecting from the seat receiving base 2 is a long hole. 62.

As interlocking means for converting the slide of the seat 4 into the forward movement of the backrest 6, a bell crank type twelfth link 64 that rotates by the slide of the seat 4, and a twelfth link 64 of the back frame 5. The twelfth link 65 and the thirteenth link 65 are connected to a bell crank type thirteenth link 65 that advances the lumbar support portion 6a of the backrest 6 by rotation (the twelfth link 64 is a link for linkage). It is engaged by a pin 66 to rotate together.

  The tip of the thirteenth link 65 is connected to a bearing bracket 67 provided on the back surface of the lumbar support portion 6a. The twelfth link 64 is pushed by a protrusion 59 b formed on the seat receiving member 59.

  The third embodiment shown in FIG. 11 is a modification of the second embodiment, and the twelfth link 64 is configured in a seesaw manner extending linearly. The back frame 5 is provided with a guide body 65 a for ensuring that the thirteenth link 65 tilts forward by the rotation of the twelfth link 64. In the second embodiment and the third embodiment, the seat 4 and the link can be returned to the neutral state by the elastic restoring force of the inner shell in the backrest 6, but a spring means for return may be provided. In the second embodiment and the third embodiment, the interlocking means can be arranged below the seat 4 and on the front side of the back frame 5, so that there is an advantage that the appearance is refreshed as a whole.

(7) Other Variations The present invention can be embodied in various ways other than the above embodiment. For example, the application target is not limited to a rotating chair for office use, but can be applied to various chairs such as a sofa for a hospital, a fixed chair for a theater or a stadium, or a vehicle chair.

  Further, the interlocking means for advancing the backrest by sitting is not limited to the configuration of the embodiment or the reference example, and various configurations can be adopted.

  The invention of the present application can also be developed as a means for adjusting the front and rear position of the seat with respect to the backrest in a chair in which the backrest does not move forward even when seated. That is, in the chair provided with the seat slide mechanism as described in the present embodiment, the seat is provided with a locking means (for example, a lever) that can lock the front and rear positions, and the front and rear position that is most comfortable to use when sitting. To lock. In this case, since the user may lift the waist and move the seat forward, it is preferable that the lowering amount of the seat is small.

The 1st reference example is shown, (A) is a side view, (B) is a perspective view of a back inner shell. (A) is a separated side view of the main member, and (B) is a partially broken separated perspective view showing an attached state of the backrest. It is a general | schematic isolation front view of the main member which fractured | ruptured some. FIG. 5 is a cross-sectional view taken along line VV in FIG. 1. It is a side view which shows the motion of a 1st reference example. It is a side view in the non-seating state of the 2nd reference example. It is a side view in the seating state of the 2nd reference example. It is a figure which shows the 3rd reference example. It is a figure which shows 1st Embodiment. It is a figure which shows 2nd Embodiment. It is a figure which shows 3rd Embodiment.

DESCRIPTION OF SYMBOLS 1 Leg support 2 Seat receiving base 3 Intermediate member 4 Seat 5 Back frame 6 Backrest 6a Lumber support part 7 Back inner shell 30 Gas cylinder 34 Actuation shaft 42 The 6th link which forms a part of interlocking means 43 eighth link that forms a part of the outer tube 50 seat receiving member 53 interlocking means forming a part of the sliding means retracting while lowering the guide shafts 49 seat forming a part of the sliding means retracting while lowering the link 48 seats (for interlocking Link)
56 Ninth link forming part of interlocking means 57 Tenth link forming part of interlocking means 59 Seat receiving member 59a Inclined portion 62 Long hole of seat receiving body 63 Guide pin 61 Eleventh link forming part of sliding means (for slide) Link)
64 12th link (link for interlocking) that forms part of interlocking means

Claims (3)

The seat has a seat and a backrest, and the backrest has a lumbar support portion against which a seated person's waist hits, while the seat is attached to a seat receiving member that slides by a sliding means so as to recede while descending It is and the seat receiving member is biased by a spring in a direction to advance and elevated, the seat you retreat while down against the spring and human sits,
The structure
The sliding means is composed of a fixed guide shaft that has a forward tilt posture with a high front and a low back, and an outer cylinder that is slidably fitted to the guide shaft. A spring that urges the outer cylinder in the direction of rising while moving forward is incorporated,
Chair. The seat has a seat and a backrest, and the backrest has a lumbar support portion against which a seated person's waist hits, while the seat is attached to a seat receiving member that slides by a sliding means so as to recede while descending The seat receiving member is urged by a spring in a forward and upward direction, and the seat recedes while descending against the spring when a person sits down,
The structure
The slide means includes a rail inclined so that the front is high and the back is low in a side view, and a slide link disposed behind the rail. The rail is provided on a base, and the seat The receiving member slides along the rail, while the slide link is rotatably connected to the seat receiving member and the base.
Chair. The seat has a seat and a backrest, and the backrest has a lumbar support portion against which a seated person's waist hits, while the seat is attached to a seat receiving member that slides by a sliding means so as to recede while descending The seat receiving member is urged by a spring in a forward and upward direction, and the seat recedes while descending against the spring when a person sits down,
In addition to the above-described configuration, further, interlocking means for advancing at least the lumbar support portion of the backrest by descending and retreating the seat is provided.
The structure
While the backrest is attached to a back frame that can be tilted rearwardly, the interlocking means has an interlocking link that is pivotally connected to the backframe, and when the seat is lowered and retracted, The interlocking link rotates without tilting the back frame backward,
Chair.

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