JP2008012227A - Chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chair which prevents a seat from being retracted and tilting backward (sinking down) by sitting on the seat in the chair which has the seat and a backrest integrally tilted backward. <P>SOLUTION: A seat 3 is attached to an intermediate member 18 which is connected to a base 2 a first supporting shaft 22. The upper end part of a backrest 4 is connected to the upper ends of back posts 19a which compose the intermediate member 18. The back post 19a and the base 2 are connected by a rear frame 48. Furthermore, the backrest 3 is held so as not to separate relative to the upper part of the rear frame 48. Additionally, the backrest 4 is supported from behind at the upper end of the rear frame 48. An elongate hole into which the first supporting shaft 22 of an intermediate member 12 fits has a horizontal posture. Further, a turning fulcrum of the rear frame 48 is arranged off nearer the rear end of the seat 3. For this reason, the seat 3 is not retracted and tilted backward by sitting on the seat. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a synchro-type chair in which a seat tilts backward while moving backward in conjunction with a backrest.

  In a chair, in order to increase the comfort of rocking (or to suppress the so-called shirt turn based on the separation of the seat and the backrest), the seat is moved backward while being retracted in conjunction with the back tilt of the backrest. (I.e., to synchronize).

  As a mechanism to retract the seat backward while interlocking with the back tilt of the backrest, the seat is generally attached to the seat frame material connected to the base by the first support shaft (slide shaft), while the backrest is the base The seat frame material and the back frame material are connected to each other so as to be relatively rotatable by the third support shaft, and the first support shaft is connected to the base. In many cases, the fitted hole is formed as a long hole in a backward inclined posture in a side view.

  On the other hand, chairs (especially office chairs) are seated in order to reduce the burden on the user's body (especially the spine) in a non-locking state and to keep the person in a good posture with his back straight. The importance of supporting the lumbar vertebrae (especially around the third lumbar vertebrae) with a backrest (the lumbar support function) has been attracting attention. ing.

  However, in conventional synchro-type chairs, the side cross-sectional shape of the backrest is constant in both the non-locking position (working position) and the locking position. Therefore, if the shape of the backrest is matched to the non-locking state, There was a problem that the body felt a strong push-up feeling (a chair has also been proposed in which the lower part of the backrest protrudes relatively forward when rocking, but in this case the push-up feeling is even greater).

In this regard, in the patent document 1, the applicant of the present application provided a back column on the tilting frame (corresponding to the intermediate member of the present application) to which a seat is attached, and connected the upper part of the backrest to the upper end of the back column, The tilt frame and the base are connected to each other by an auxiliary frame (corresponding to the rear frame of the present application) so as to be relatively rotatable, and a portion of the auxiliary frame above the connection point with respect to the tilt frame is connected to the backrest. We proposed a chair with a flexible structure so that the shape in the longitudinal side view can be easily changed.
Japanese Patent Application No. 2005-33632

  According to this prior application, the degree of backward tilting of the rear frame is greater than the degree of backward tilting of the tilting frame. Will be stretched and deformed toward a certain state, that is, the entire backrest will bend or flattened, and therefore the softness of hitting the body in lumbar support function when not locked Can be secured, and at the time of rocking, there is no sense of pushing up the body due to the backrest and the fit can be improved.

  The present invention is an improvement that follows the previous application, and it is an object to ensure the certainty of locking while preventing the seat from retreating and tilting backward when sitting, without impairing its advantages. It is what.

  The chair according to the present invention includes a base supported by legs, a seat disposed above the base, a backrest having flexibility so that the longitudinal side view shape can be easily changed, and a seat attached to the base. Includes an intermediate member coupled so as to be able to tilt backward while moving backward, a rear frame that pushes the backrest from the rear, and spring means that elastically supports the backward movement and backward tilting of the intermediate member. .

  The intermediate member is integrally provided with a back strut, and the back strut holds the upper portion of the backrest in an inseparable manner, while the rear frame is connected to the base so as to be able to tilt rearward and up and down. The rear frame is connected to the back strut so that it can be rotated relative to the back strut. It is designed to stretch and deform from a flat state to a flat state.

  According to a second aspect of the present invention, in the first aspect, the first support shaft is attached to the intermediate member as a connecting means to the base. The first support shaft is attached to the base and the first support shaft slides back and forth. The elongated hole that fits freely is formed to extend in a substantially horizontal posture in a side view. In the invention of claim 3, the intermediate member is connected to the base at a portion near the front end of the seat.

  According to the present invention, it is possible to accurately support the user's lumbar vertebra in the non-locking state and secure the fitting property when locking, but the connecting portion (the portion of the pivotal fulcrum) of the intermediate member is substantially back and forth in the horizontal direction. Therefore, the load due to the seating does not act to retract the intermediate member, and the intermediate member retracts only when the user leans on the backrest.

  Therefore, even if the spring force of the locking spring is weak, the seat can be held in a stable state in the non-locking state while ensuring proper support of the lumbar vertebra in the non-locking state and fit in the locking state.

  As a means for connecting the intermediate member and the base, it is possible to form a long hole in the intermediate member by fixing a horizontally long shaft to the base, but from the support shaft and the long hole as in claim 2 Adopting such a combination has the advantage that the structure is simple. Further, since the pivot point of the rear frame is located near the rear part of the seat, the load due to the seating does not act so as to tilt the rear frame with respect to the rear frame. Since the seat is supported from the rear so as not to tilt backward, it is possible to more reliably prevent the seat from being retracted and tilted backward by the seating.

  According to the third aspect of the present invention, the seat tilts backward with a portion near the front end thereof as the center, so that there is an advantage that the seat can be prevented from tilting backward and the thigh of the seated person being pushed up.

  Next, an embodiment of the present invention will be described with reference to the drawings.

(1). Outline of chair First, the outline of the chair will be described with reference to FIGS. 1A is a front view, FIG. 2B is a right side view, FIG. 2A is a plan view, FIG. 1B is a cross-sectional view taken along the line IIB-IIB in FIG. Is a rear view, (D) is a longitudinal side view of only the seat and the backrest, and FIG. 3 is a longitudinal side view of the chair.

  The chair includes a leg 1, a base 2 attached to the upper end of the leg 1, a seat 3 disposed above the base 2, and a backrest 4 disposed behind the seat 3. The leg 1 includes a pedestal 5 made of a gas cylinder, and branch legs 6 extending radially from the pedestal 5, and a caster 7 is provided at the tip of each branch leg 6. The lock of the pedestal 5 can be released by operating a lever 8 (see FIG. 1A) provided on the base 2.

  As shown in FIGS. 2 (D) and 3, the seat 3 includes front and rear inner shells (seat plates) 9 and 10 made of resin and a cushion body 11 stretched so as to extend in series on the upper surface thereof. Therefore, the seat 3 includes a seat rear portion 3b that does not move unless the backrest 4 is locked, and a seat front portion 3a that can be independently tilted forward.

  The backrest 4 has a structure in which a cushion 4b is stretched on the front surface of the back inner shell 4a, and a back cover 12 extending over almost the entire height of the back inner shell 4a is disposed behind the back inner shell 4a ( The back cover 12 is fixed to the back column). Further, the space between the back cover 12 and the base 2 is closed by a rear cover 13, and a front cover 14 is mounted in front of the base 2. A front lever knob 15 for tilting the front portion 3a is exposed. The front cover 14 is attached to the front inner shell 9 of the seat 3. Reference numeral 16 shown in FIGS. 1 and 2 is a lever that switches the backrest 4 between a state in which the backrest 4 can be tilted backward and a state in which the backrest cannot be tilted.

(2) Details of the seat Next, the seat 3 and its peripheral part will be described in detail with reference to FIGS. 4 is an exploded perspective view showing the support mechanism of the seat 3, FIG. 5 is an exploded perspective view of the base and the receiving member, FIG. 6 is an exploded perspective view of the seat inner shells 9 and 10, and FIG. 8 is a plan view with the seat omitted, FIG. 9 is a partial cross-sectional view taken along the line IX-IX of FIG. 8, FIG. 10 is a partial cross-sectional view taken along the line XX of FIG. It is sectional drawing which shows the mechanism made to incline forward.

  The base 2 has a housing shape opened upward, and an intermediate fitting 18 to which the seat 3 and the backrest 4 are attached is disposed between the seat 3 and the base 2, for example, as shown in FIG. 4. The intermediate fitting 18 has two left and right pipes 19 as main members, and the rear end of the pipe 19 extends upward to form a back column 19a. That is, in this embodiment, the seat 3 and the backrest 4 are attached to one intermediate fitting 18.

  A front bracket 20 having a U-shaped opening facing upward is fixed to the front part of the left and right pipes 19 constituting the intermediate metal fitting 18 by welding. Then, left and right laterally long first support shafts (slide shafts) 22 are fixed to the left and right front brackets 20 by welding, and the horizontal portions of the left and right pipes 19 are a first connection portion body 23 and a second connection body. 24 are integrally connected.

  As shown in FIG. 3, a resin seat outer shell (seat receiving plate) 25 is disposed below the rear inner shell 10, and the rear inner shell 10 is detachably fixed to the seat outer shell 25. The seat outer shell 25 is fixed to the first connecting body 23 of the intermediate fitting 18 with screws or the like.

  As can be understood from FIGS. 4 and 9, the first support shaft 22 of the intermediate bracket 18 is sandwiched between a lower receiving member 26 and an upper receiving member 27 that are vertically overlapped, and the upper receiving member 27 has a pressing member. 28 are overlapped, and these three members are fastened together with screws (not shown) to the base 2 in a state of being overlapped with each other. The first support shaft 22 is disposed at a site near the front of the seat 3. Specifically, it is disposed at a position that is close to the front by a dimension of about 2/3 of the entire length of the seat 3 or slightly ahead of it.

  As shown in FIG. 5, the lower receiving member 26 has four front and rear, left and right engaging holes 26a penetrating vertically, while the base 2 has a boss body 2a into which the engaging hole 26a fits tightly. Are integrally formed, and the lower receiving member 26 is held immovably in the horizontal direction by fitting the lower receiving member 26 into the boss body 2a. The pressing member 21 is fastened to the boss body 2a with screws. The boss body 2a is constricted, so that the lower receiving member 26 can be easily fitted and cannot be displaced.

  The base 2 is formed with a center protrusion 2b with which the rear end of the lower receiving member 26 comes into contact, a hole 2c in which the pedestal 5 is fitted, an overhang portion 2d for attaching an armrest (not shown), and the like. The base 2 and the upper and lower receiving members 26 and 27 are die-cast products such as aluminum, and the pressing member 28 is a sheet metal product. Of course, the material and processing method of each member can be arbitrarily selected.

  In the upper and lower receiving members 26 and 27, a long groove 29 that allows the first support shaft 22 to slide back and forth is formed to extend horizontally. The upper and lower long grooves 29 overlap with each other to form a long hole (thus, in this embodiment, the long groove 29 is synonymous with a long hole). Further, the long groove 29 of the lower receiving member 26 is deeper than the long groove 29 of the upper receiving member 27. This is to ensure the support strength of the first support shaft 22. The long groove (long hole) 29 may be inclined backward if it is at a certain angle.

  Further, a spring (compression coil spring) 30 is arranged between the upper and lower receiving members 26 and 27 so as to extend in the front-rear direction, and a rear end for supporting the spring 30 from the rear at the rear end of the lower receiving member 26. A wall 31 is formed. On the other hand, a front spring receiver 32 that supports the spring 30 from the front is overlapped with the first support shaft 22 of the intermediate fitting 18. Therefore, the intermediate metal fitting 18 (and the seat 3 and the backrest 4) can slide backward against the spring 30 and can tilt backward about the first support shaft 22.

  As shown in FIG. 6, the front inner shell 9 has a substantially flat plate shape, and the rear inner shell 10 is gently bent upwardly concave in a front view, and is gently curved upwardly concave in a longitudinal front view. ing. The front and rear inner shells 9, 10 are connected to bendable by passing a connecting pin 35 through a pair of left and right cylindrical bearing portions 33 and a semicircular bearing portion 34. The connecting pin 35 is located slightly behind the first support shaft 22 (in other words, the first support shaft 22 is positioned in front of the bending point of the seat front portion 3a).

  The cylindrical bearing portions 33 are located closer to the left and right ends, respectively, and the semicircular bearing portion 34 is located closer to the middle portion. In this embodiment, the cushion 11 is integrally formed by the insert molding method after the front and rear inner shells 9 and 10 are connected. However, the cushion 11 can be separately manufactured and attached.

  The seat outer shell 25 is disposed directly below the rear inner shell 10, and the rear inner shell 10 is attached to the seat outer shell 25 by fitting the claw-like engagement portion 36 and the hole-like engagement portion 37. As described above, the seat outer shell 25 is fixed to the intermediate fitting 18.

  As shown in FIGS. 9 and 10, the long grooves 29 of the upper and lower receiving members 26 and 27 extend in the horizontal direction. For this reason, even if the spring force of the spring 30 is not excessively large, the seat 3 does not tilt backward only by a person sitting on the seat 3.

  By the way, in the conventional synchro-type chair, the first support shaft is fitted into a long hole in a backward tilting posture in a side view. For this reason, if the spring force of the spring is weak, the seat tilts backward due to the seating. If a strong spring is used, the resistance against the backward tilt of the backrest 4 is too strong.

  On the other hand, when the first support shaft 22 is moved horizontally as in the present embodiment, the seating load W does not act to retract the seat 3 (all of the load W acts downward, 1) Since the seat 3 is retracted only when a person leans on the back 4), the spring 30 can be used with a spring force much weaker than before. For this reason, even if a user (especially a woman) with a light weight is using and leaning on the backrest 4, the backrest 4 can be easily tilted backward to ensure a comfortable locking state. Moreover, it is advantageous also in terms of cost.

(3). Forward tilt structure of seat front part Next, a mechanism for tilting the seat front part 3a will be briefly described with reference to FIG. 11A is a longitudinal side view of the intermediate bracket 18 in the vicinity of the front bracket 20, and FIG. 11B is a longitudinal side view of the left and right intermediate portion. As shown in FIG. 4, a forward projecting portion 20a is formed at the front end of the front bracket 20, and a bearing member 38 shown in FIG. 11 is overlaid from above the projecting portion 20a.

  The bearing member 38 includes one side plate 38 a, a support surface 38 b located inside the side plate 38 a, and a rearward convex portion 38 c that fits inside the front bracket 20, and the rearward convex portion 38 c is a pin 39. And attached to the front bracket 20.

  The center shaft 40a of the front lever 40 is rotatably fitted to the side plate 38a of the bearing member 38. Further, a cam member 42 having a long hole is placed on the support surface 38b of the bearing member 38, and the left and right root portions of the center crank portion 40b of the front lever 40 are fitted into the long hole of the cam member 42. . The posture of the cam member 42 can be freely changed between an upright posture and a forward leaning posture by rotating the front lever 40. The front inner shell 9 is formed with a downward projection 43 that holds the cam member 42 in an upright state.

  As shown in FIG. 11 (B), the left and right intermediate portions of the center crank portion 40b of the front lever 40 are fitted into guide holes 44 having a downwardly concave arc shape formed on the front surface of the front inner shell 9 in a side view. . The guide hole 44 is formed by attaching a lower guide member 45 from below to a downward concave circular arc portion 9 a formed in the front inner shell 9.

  The long and narrow knob 15 described above is attached to the left and right ends of the front lever 40. When the cam member 42 is rotated by operating the knob 15, the center crank portion 40b of the front lever 40 is tilted forward. Thus, the seat front portion 3a is pushed downward, whereby the seat front portion 3a is tilted forward about the connecting pin 59. The forward tilt angle is set to about 15 degrees.

(4). Backrest Mounting Structure Next, the mounting structure for the backrest 4 will be described with reference to FIGS. 3 and 12. FIG. 12 is an exploded perspective view.

  As shown in FIG. 3, the backrest 4 includes a resin back inner shell 4a and a cushion 4b stretched on the front surface thereof (of course, a cross is also stretched). By forming a horizontally long slit, etc., the side view shape can be changed with a light force. The upper ends of the left and right back posts 19a are connected by an upper connecting body 47 having a U-shaped cross section, and the upper end portion of the back inner shell 4a is fixed (connected) to the upper connecting body 47.

  Further, as a support mechanism for the backrest 4, a rear frame 48 having a substantially L-letter shape in a side view having two pipe members on the left and right sides is disposed. A second support shaft 50 is integrally fixed to front end portions of the left and right pipes constituting the rear frame 48 via a bracket plate 49. The second support shaft 50 is sandwiched between the rear portion of the base 2 by a vertically split bearings 51 and 52, and the bearings 51 and 52 are fixed to the base 2 by screws with a pressing member 53. ing. Accordingly, the rear frame 48 can tilt about the second support shaft 50.

  In FIG. 3, the bearings 51 and 52 for the second support shaft 50 should originally be displayed in cross section, but the cross section display (hatching) is omitted for the sake of simplicity. In FIG. 12, only the upper bearing member 51 is shown.

  A fourth connector 54 made of a metal plate is integrally fixed to the lower part of the left and right pipes constituting the rear frame 48, and a fifth connector 55 made of a metal plate is integrally attached to the upper ends of the left and right pipes. It is fixed to. The fourth connecting body 54 includes a forward groove 54 a and upper and lower blades 54 b, while a third support shaft 57 is integrally fixed to the lower portion of the left and right back struts 19 a via a bracket material 56.

  The third spindle 57 is sandwiched between upper and lower split-type front and rear bearings 58 and 59, and the front and rear bearings 58 and 59 are connected to the third connecting body via a pressing member 60 that overlaps the front and rear bearings 58 and 59 from the front. 33 is fixed. Accordingly, the intermediate bracket 18 (back strut 19a) and the rear frame 48 rotate in conjunction with each other. The rear bearing 58 is fitted in the forward groove 54 a of the third connecting body 54, and the pressing member 50 is fastened to the upper and lower blades 54 b of the third connecting body 54 with screws.

  The fourth connecting body 55 in the rear frame 48 is integrally formed with a pair of left and right bearing pieces 55a extending upward, and a roller 62 is rotatably fitted on a pin 61 inserted through the left and right bearing pieces 55a. The roller 62 is applied to the back surface of the back inner shell 4a. The vertically long central portion of the back inner shell 4a is pushed and bent in a forwardly convex shape in a side view so that the portion where the roller 62 hits is located closest to the front. Further, the forward apex portion of the back inner shell 4a is set to be substantially the same height as the third lumbar vertebra of the seated person.

  As shown in FIG. 3, a portion of the rear surface of the back inner shell 4 a located at a portion between the third connecting body 54 and the fourth connecting body 55 of the rear frame 48 is a box-shaped bracket portion protruding backward. A horizontally long locking pin 64 is integrally provided through 63 (the locking pin 64 may be a separate member from the back inner shell 4a).

  On the other hand, as can be understood from FIG. 3, a guide body 65 into which the locking pin 64 is fitted is fixed to the third connection body 54 and the fourth connection body 55 of the rear frame 48 with screws. The guide body 65 has a guide groove 65a that is vertically long and has a lower portion opened forward, and the back inner shell 4a faces forward from the rear frame 48 by fitting a locking pin 64 into the guide groove 65a. It is kept inseparable. The rear frame 48 is covered with an auxiliary cover 66 from the front. The reason why the lower portion of the guide groove 65a opens forward is to allow the locking pin 64 to be fitted from the front.

  As can be understood from FIG. 3, the rear frame 48 is attached to the base 2 at a portion near the rear end of the seat 3. For this reason, a load acts on the rotation fulcrum of the rear frame 48 when a person is seated. It is shifted backward from the center point (the position of the white arrow in FIG. 3). For this reason, when a person is seated and not leaning against the backrest 4, the intermediate member 18 (and the back column 19 a) is supported upward from the rear by the rear frame 48. The first support shaft 22 is prevented from moving backward simply by being seated.

(5) Movement of the seat and the backrest FIG. 13 is a diagram schematically showing the framework of the chair, and the movement of the seat 3 and the backrest 4 will be described based on FIG. In this embodiment, since the seat 3 and the backrest 4 are attached to the intermediate fitting 18, the seat 3 and the backrest 4 tilt backward together. Since the rear frame 48 and the back column 19a (intermediate metal fitting 18) are connected, the rear frame 48 also tilts backward in conjunction with the rearward tilt of the back column 19a. Since the rear frame 48 is positioned behind the pivot point of the support column 19a, the rear frame 48 tilts backward at a larger angle than the back support column 19a.

  For this reason, the roller 42 is inclined backward relative to the back column 19a. And since the lower part of the back inner shell 4a has the locking pin 44 fitted in the guide body 45 and is held so as not to be separated from the rear frame 48, when the roller 42 moves backward relative to the back column 19a, The back inner shell 4a is stretched and deformed (stretched) from a state in which it is greatly deformed to a forwardly convex shape in a side view in the longitudinal direction. That is, when the backrest 4 (back inner shell 4a) is tilted rearward, the backrest 4 (back inner shell 4a) tends to expand toward a flat state.

  When a seated person performs an operation such as keyboard operation with the upper body in an upright posture or a slightly tilted posture, the lumbar vertebra (especially around the third lumbar vertebra) is supported by the backrest 4 so that the person maintains a stable posture. it can. On the other hand, if the backrest 4 remains largely curved in a forwardly convex shape at the time of locking, the upper body of the person is bent into a state of sliding away, but lacks comfort, but in this embodiment, the backrest 4 is flat in the locked state. Since it is easy to grow, the fit is high and the user's body does not feel uncomfortable.

  Further, as the backrest 4 becomes easy to extend, as a result, the backrest 4 tilts backward at a larger angle than the seat 3, so that the seat 3 and the backrest 4 are attached to the intermediate bracket 18 (back inner shell 4 a). The back tilt angle required for the backrest 4 can be maintained while being attached.

  In addition, the front-rear width dimension of the seat front portion 3a is set to about 200 mm, and is shorter than half of the overall length (front-rear width dimension) of the seat 3.

  The horizontal posture of the long hole 29 through which the first support shaft 22 slides is an example of a restricting means for preventing the seat from moving backward and tilting due to the seating. It is also possible to make the front end of the elongated hole in a posture inclined forward, or to form a recess in which the first support shaft slightly falls at the front end position of the elongated hole. Such a restricting means can also be applied when the long hole is inclined in a side view.

(6). Others Although the embodiment of the present invention has been described above, the present invention can be embodied in various other forms. For example, the shape of each member such as a base, a seat, an intermediate member, a rear frame, and a backrest can be changed in any way as long as the function is maintained. For example, the intermediate member or the back strut can be a sheet metal product or a die cast product, or the portion of the intermediate member to which the seat is attached can be a sheet metal product or a die cast product, and the back strut can be made of a metal pipe material.

  Further, the connecting means between the members is not limited to using a support shaft (pin), and a boss portion provided on one member can be fitted into a hole provided on the other member. The present invention can also be applied to a chair of a type in which a seat and a backrest are attached to different frame materials.

  The intermediate member may be directly connected to the base with a support shaft without using upper and lower receiving members, and other members can be interposed between the intermediate member attached to the base and the seat. It is. Further, a member corresponding to the intermediate member (for example, brackets) can be provided directly on the base, and therefore the back column may be fixed to the seat.

It is the front view and right view of a chair. FIG. 2 is a plan view of the chair, a sectional view taken along the line IIB-IIB in FIG. 1 (A), a rear view, and a longitudinal side view of only a seat and a backrest. It is a vertical side view. It is a separate perspective view of the member which comprises a seat part. It is a separate perspective view of a base and a lower receiving part seat. It is a separation perspective view of front and rear inner shells. It is a perspective view of a seat outer shell. It is a partial top view in the state where a seat was omitted. It is the IX-IX partial sectional view of FIG. FIG. 9 is a partial cross-sectional view taken along the line X-X in FIG. 8. It is a figure which shows the mechanism for tilting forward the seat front part. It is an isolation | separation perspective view which shows the support structure of a backrest. It is a key map explaining movement of a seat and a backrest.

Explanation of symbols

1 leg 2 base 3 seat 3a seat front 3b seat back 4 backrest 9, 10 seat inner shell 18 intermediate bracket 19a back strut 22 first support shaft 29 long groove (long hole)
30 Spring for locking 48 Rear frame 50 Second support shaft 57 Third support shaft

Claims (3)

A base supported by the legs, a seat arranged above the base, a backrest that is flexible so that the longitudinal side view shape can be easily changed, and the seat is attached and the base is moved backwards An intermediate member coupled so as to be able to tilt; a rear frame that pushes the backrest from the rear; and spring means that elastically supports the backward and rearward tilting of the intermediate member,
The intermediate member is integrally provided with a back strut, and the upper portion of the backrest is held by the back strut in an inseparable manner, while the rear frame is connected to the base so as to be able to tilt backward and has a vertically middle part. In the state where the backrest protrudes forward in a longitudinal side view as the vehicle is tilted backward by increasing the degree of rearward tilting of the rear frame compared to the degree of backward tilting of the rear column. It is designed to stretch and deform toward a flat state from
A chair called
A portion that serves as a tilting fulcrum of the intermediate member is attached to the base in a state of moving back and forth in a substantially horizontal direction.
Chair. The intermediate member is attached with a laterally long first support shaft as a connecting means to the base, while the base has an elongated hole into which the first support shaft is slidably fitted back and forth in a side view. It is formed to extend in the posture of
Further, the rear frame is connected to the base at a portion near the rear end of the seat,
The chair according to claim 1. The intermediate member is connected to the base at a portion near the front end of the seat,
The chair according to claim 1 or 2.

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