JP5578668B2 - Chair - Google Patents

Description

  The present invention relates to a chair suitably used in an office or the like.

  2. Description of the Related Art Conventionally, as one of this type of chair, a chair with a backrest attached to left and right back support arms extending in the front-rear direction is known (for example, see Patent Document 1).

  In the prior art, a protrusion projecting forward is provided on the front surface of the lower end portion of the back frame of the backrest, and the backrest is attached to the support arm by combining the protrusion and the rear end portion of the back support arm. To be installed on.

  However, since such a mounting portion is located at an intricate portion on the lower side of the seat, there is a problem that the mounting operation is difficult.

JP 2008-148997 A

  The present invention has been made paying attention to the above situation, and it is an object of the present invention to provide a chair that can solve the problem that it is difficult to attach the back frame to the back support arm.

  That is, the chair of the present invention is a chair having a backrest attached to the left and right back support arms extending in the front-rear direction, and the backrest includes a back frame having downward projecting portions on the left and right sides at the lower end. And each back support arm has an upward concave portion at the rear end, and the projecting portions are fitted into the concave portions of the both back support arms, respectively. It is supported by the both back support arms.

  With such a configuration, the back frame of the backrest is fitted and held from the upper side to the rear ends of the left and right back support arms, and an appropriate fastening operation can be performed in this state.

  In order to improve the appearance without incurring a significant increase in assembly man-hours, a decorative plate that covers the middle portion of the lower end of the back frame from the lower side is provided, and the left and right back support arms are The decorative plate is provided with a support portion for supporting the end portion of the decorative plate, the decorative plate is installed between the support portions, and the back frame is attached to the both back support arms to attach the decorative plate to the back plate. It is preferable to be attached to a frame. In addition, as an aspect which constructs the said decorative board, there exists a thing which constructs the said decorative board in the temporary placement state between the said support parts.

  Specific embodiments of the chair include a leg having leg blades, a support base that is supported by the leg and rotatably supports the left and right back support arms, and a seat disposed on the support base. And a locking mechanism that moves the seat in accordance with the backward tilting motion of the backrest.

  There are various locking mechanisms, and if the present invention is applied to a chair having a weight-sensing locking mechanism configured to move up the seat as the backrest is tilted backward, Particularly preferable effects as described later can be obtained.

  As a specific aspect to which the decorative plate is attached, there is one in which both ends of the decorative plate are sandwiched between the left and right back support arms and the back frame.

  Moreover, in order to avoid suitably the positional shift of the said decorative board and a back frame, the said decorative board has an upward recessed part opened upwards, The rib provided in the said back frame and the said upward recessed part Are preferably engaged with each other.

  As a specific coupling mode between the back support arm and the back frame, the left and right back support arms are each provided with an inner standing portion and an outer standing portion that form the concave portion at a rear end portion, respectively. The aspect which attaches the back frame which each fitted the said protrusion part to the recessed part of the said left and right back support arm to the outer standing part of each said back support arm via a fastening tool can be mentioned. As a more specific aspect in this case, the outer standing portion includes an outer wall that forms one inner surface of the recess, and a front wall that extends inwardly from the front edge of the outer wall. The back frame is provided with a groove that fits into the front wall from above and below.

  The lower end of the back frame has a concave shape so as to form a U shape when viewed from the back.

  As described above, according to the present invention, it is possible to provide a chair that solves the problem that it is difficult to attach the back frame to the back support arm.

The perspective view from the back which shows one Embodiment of this invention. The front view which shows the same embodiment. The rear view which shows the same embodiment. The left view which shows the same embodiment. The perspective view from the front which decomposes | disassembles and shows the support base part of the embodiment. The perspective view from the back which decomposes | disassembles and shows the support base of the embodiment. The schematic sectional side view which shows the principal part of the tilt lock mechanism of the embodiment. FF sectional view taken on the line in FIG. The front view which shows the principal part of the support base of the embodiment. The expanded rear view which shows the principal part of the support base of the embodiment. The left view which shows the support base and seat of the embodiment. Action explanatory drawing equivalent to FIG. 11 which shows the locking mechanism of the embodiment. The disassembled perspective view which shows the seat and seat receiver of the embodiment. The enlarged bottom view which shows the seat of the same embodiment, a seat receiver, and an armrest. AA line sectional view in FIG. BB sectional drawing in FIG. CC sectional view taken on the line in FIG. Explanatory drawing which shows the attachment aspect to the back support arm of the backrest in the embodiment. Explanatory drawing which shows the attachment aspect to the back support arm of the backrest in the embodiment. The DD sectional view taken on the line in FIG. Explanatory drawing which shows the attachment aspect of the lumbar support apparatus in the embodiment. EE sectional view taken on the line in FIG. Action | operation explanatory drawing which shows the principal part of the lumbar support apparatus in the embodiment. Action | operation explanatory drawing which shows the principal part of the lumbar support apparatus in the embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  In this embodiment, the present invention is applied to an office swivel chair.

  As shown in FIGS. 1 to 4, the chair includes a leg 1, a support base 3 supported by the leg 1, a seat receiver 5 disposed on the support base 3, and a support supported by the seat receiver 5. The seat 7, the back support arm 9 rotatably supported by the support base 3, the backrest 11 attached to the rear end of the back support arm 9, and the back tilting operation of the backrest 11 are accompanied. And a locking mechanism 13 for moving the seat receiver 5 and the seat 7 upward and downward.

《Leg composition》
As shown in FIGS. 1 to 4, the leg 1 includes a leg base 15 and a leg support 17 provided at the center of the leg base 15.

  As shown in FIGS. 1 to 4, the leg base 15 is provided with a plurality of leg blades 19 projecting radially from a hub 18 provided at the center, and a caster 21 is provided at the tip of the leg blade 19. Provided.

  As shown in FIGS. 1 to 4, the leg strut 17 is a gas spring type that is elastic in the vertical direction and can be locked at a desired position. That is, the leg strut 17 includes a gas spring main body 23 fitted to the hub 18 of the leg base 15 and a rod 25 protruding from the upper end of the gas spring main body 23. An operation button (not shown) for unlocking is projected. The support base 3 is attached to the upper end of the rod 25. The unlocking operation button is operated by an elevating operation lever 83 provided on a seat receiver 5 described later.

《Support base configuration》
As shown in FIGS. 2 to 11 and 17, the support base 3 includes a main frame 27 attached to the rod 25 of the leg support 17, and a front link shaft 29 and a support shaft 31 attached to the main frame 27. It is provided. The front link shaft 29 is for supporting the front end portion of the seat receiver 5 via the front link 33. The support shaft 31 supports the back support arm 9 and supports the intermediate portion of the seat receiver 5 via the rear link 35.

  As shown in FIGS. 5 to 9 and 11, the main frame 27 includes a boss portion 37 fitted to the upper end portion of the rod 25 in the leg column 17 and a half-view in plan view surrounding the upper end side of the boss portion 37. A rear frame member 39 having an arc shape, a pair of side frame members 41 extending forward from the left and right front ends of the rear frame member 39, and the front end portions of the side frame members 41 are joined to each other to be flat at the front end. And a front frame member 43 having a surface. The boss portion 37, the rear frame member 39, the side frame member 41, and the front frame member 43 are integrally formed by aluminum die casting or the like. A front bearing portion 45 that supports the front link shaft 29 is integrally provided on the upper surface portion of the front frame member 43, and the support shaft is located near the boundary between the rear frame member 39 and the side frame member 41. A bearing 47 for supporting 31 is integrally provided.

  As shown in FIGS. 5, 6, 7, 8, 11, and 17, the main frame 27 includes a tilt reaction force generation mechanism 49 that biases the backrest 11 forward, and the tilt. A tilt lock mechanism 51 for locking the backrest 11 at a predetermined position against the urging force of the reaction force generation mechanism 49 is incorporated.

  As shown in FIGS. 5, 6, 7, 8, 11, and 17, the tilt reaction force generation mechanism 49 is used for torque transmission that forms a pair of left and right base ends supported by the support shaft 31. A bracket 59, a movable shaft 55 installed between the tip portions of the left and right torque transmitting brackets 53, and a spring 59 that elastically biases the movable shaft 55 in the rear direction with a spring receiver 57 provided on the main frame 27 as a scaffold. It comprises.

  As shown in FIGS. 5, 6, 7, 8, and 11, the tilt lock mechanism 51 is disposed in the cavity 61 of the main frame 27 surrounded by the frame members 39, 41, and 43. . The tilt lock mechanism 51 has a base end portion supported by the support shaft 31 and rotated in the vertical direction in conjunction with a torque transmission bracket 53, and covers the rotation housing 63. A fixed housing 69 fixed to the main frame 27 and provided with a plurality of stages of hook holes 67 on both side walls 71. The backrest 11 is secured by locking the rotating housing 63 to the fixed housing 69. It can be locked at a predetermined tilting position. That is, the tilt lock mechanism 51 includes an engaging claw 72 that is provided so as to protrude and retract on the side wall 65 of the rotating housing 63 and selectively engages with any one of the hook holes 67 of the fixed housing 69. A tilting lock releasing arm 74 for forcibly moving the joint claw 72 in the immersion direction and releasing the locked state between the fixed housing 69 and the rotating housing 63 is provided. As shown in FIG. By operating 74 with an operating lever 75 for adjusting locking provided on the side surface 73 of the seat receiver 5, the lock can be released. An operation force transmission mechanism 76 for transmitting the operation of the tilt lock release arm 74 to the engagement claw 72 is provided between the tilt lock release arm 74 and the engagement claw 72. The operating force transmission mechanism 76 connects the distal end portion 78a to the engaging claw 72, and advances and retracts the surrounding portion of the distal end portion of the tilt lock release arm 74 with a base end portion 78b having a frame shape. And a spring sp which is disposed in the base end portion 78b and transmits the operation in the releasing direction of the tilt lock releasing arm 74 to the advancing and retracting member 78. The engaging claw 72 is a plate-like one that is rotatably supported by the top plate 63 a of the rotating housing 63, and both end portions 72 a protrude from the side wall 65 of the rotating housing 63 and engage with the hook holes 67 of the fixed housing 69. It can be swung between a lock position (shown by a solid line in FIG. 8) and a lock release position (shown by a two-dot chain line in FIG. 8) that is disengaged from the hook hole 67. Here, reference numeral 77 denotes a locking adjustment wire for transmitting the operating force of the locking adjustment operating lever 75 to the tilt lock release arm.

  When the operating lever 75 for adjusting the locking is operated, the locking adjusting wire 77 is pulled, and the tilting lock releasing arm 74 is rotated. At the tip of the tilting lock releasing arm 74, the engaging claw 72 locks the spring sp. Is urged in the direction to move to the unlocking position. At this time, while a large frictional force is acting between the engaging claw 72 and the hook hole 67 of the fixed housing 69, the advancing / retreating member 78 and the engagement member 78 are engaged even if the tilt lock release arm 74 rotates in the above-described direction. The pawl 72 remains held in the locked position, and the spring sp is compressed. When the friction between the engaging claw 72 and the hook hole 67 is eliminated from this state, the reciprocating force of the spring sp causes the advance / retreat member 78 and the engaging claw 72 to operate in the unlocking direction, and the locked state is established. Canceled. When the operating force by the locking adjustment wire 77 is lost, the tilting lock release arm 74 is rotated in a direction to move the engagement claw 72 from the lock release position toward the lock position by the biasing force of a return spring (not shown). Even when the engaging claw 72 rotates in the lock position direction, the tips of both end portions 72 a of the engaging claw 72 abut on the inner surface of the fixed housing 69 at a rotating position where it cannot engage with the hook hole 67. To enter a standby state. Then, when the tilting position of the backrest 11 is changed and the engaging claw 72 is aligned with the hook hole 67, both end portions 72a of the engaging claw 72 are engaged with the corresponding hook holes 67 to be locked. .

  Reference numeral 79 denotes a lifting / lowering unlocking arm for pressing an unlocking operation button provided on the rod 25 of the leg post 17. As shown in FIG. It is a lifting wire for transmitting the operating force of the provided lifting control lever 83 to the lifting lock release arm 79.

  The support base 3 is covered with an upper cover 85 and a lower cover 87 as shown in FIGS. 5, 6, and 9.

  As shown in FIGS. 5, 6, and 9, the upper cover 85 covers the support base 3 from the upper surface side, and has upper locking claws 89 and 91 that protrude downward to engage with the support base 3. Is provided. The lower cover 87 covers the support base 3 from the lower surface side, and is provided with lower locking claws 93 and 95 protruding upward to engage with the support base 3. Further, the upper cover 85 and the lower cover 87 are arranged so that the opening end edges 97 and 99 abut each other.

  As shown in FIGS. 5, 6, 9, and 10, the upper and lower shared mounting portions 101 and 103 for mounting the upper cover 85 and the lower cover 87 are provided on the outer peripheral surface of the main frame 27 of the support base 3. Is provided.

  More specifically, the main frame 27 of the support base 3 has upper locking claws 89 and 91 and lower locking of the lower cover 87 as shown in FIGS. 5, 6, 9 and 10. The upper and lower shared mounting portions 101 and 103 for engaging the claws 93 and 95 respectively are provided, and the upper and lower shared mounting portions 101 and 103 are engaged end surfaces 105 with which the upper locking claws 89 and 91 are engaged. 109, engaging end surfaces 107 and 111 with which the lower locking claws 93 and 95 are engaged, locking end surfaces 113 and 117 for preventing lateral shift for locking lateral shift of the upper locking claws 89 and 91, and Locking end faces 115 and 119 for preventing a lateral shift for locking the lateral shift of the lower locking claws 93 and 95 are provided.

  Specifically, as shown in FIGS. 5, 6, 9 and 10, the main frame 27 includes a pair of front shared upper and lower mounting portions 101 and a single rear shared upper and lower mounting. The upper locking claw 89 and the lower locking claw 93 are provided at portions corresponding to the upper and lower shared mounting portions 101 of the upper and lower covers 85 and 87.

  As shown in FIGS. 5 and 9, the front upper / lower common mounting portion 101 is provided on the outer peripheral surface 121 at the front end of the front frame member 43 in the main frame 27, and the outer peripheral surface 121 at the front end is rectangular. It is a depression. In the front upper / lower common mounting portion 101, the upper side is the engagement end surface 105 with which the upper locking claw 89 of the upper cover 85 is engaged, and the lower side is the engagement end surface 107 with which the lower locking claw 93 of the lower cover 87 is engaged. . Further, in the front upper and lower shared mounting portion 101, the left and right sides are locking end surfaces 113 and 115 for preventing lateral displacement with respect to the upper locking claw 89 and the lower locking claw 93 of the upper cover 85 and the lower cover 87.

  As shown in FIGS. 6 and 10, the rear upper / lower common mounting portion 103 is provided on the outer peripheral edge 122 of the rear end of the rear frame member 39 in the main frame 27, and has a substantially horizontal central ridge 123. The central ridge 123 includes a pair of side ridges 125 arranged at different heights on both sides. In the rear upper / lower common mounting portion 103, the lower edge of the side protrusion 125 is the engagement end surface 109 with which the upper locking claw 91 of the upper cover 85 is engaged, and the upper edge of the central protrusion 123 is the lower engagement of the lower cover 87. It is the engagement end surface 111 with which the pawl 95 engages. Further, in the rear upper / lower common mounting portion 103, the left and right edges of the central protrusion 123 are locking end surfaces 117 for preventing lateral displacement with respect to the upper locking claws 91 of the upper cover 85, and the inner edge of the side protrusion 125. Is a locking end surface 119 for preventing lateral displacement with respect to the lower locking claw 95 of the lower cover 87.

  As shown in FIGS. 5 and 6, the upper dedicated mounting portion 127 for mounting the upper cover 85 and the lower dedicated mounting portion 129 for mounting the lower cover 87 are provided near the middle in the front-rear direction on the outer periphery of the main frame 27. And are provided. The upper cover 85 is provided with a claw 131 that engages with the upper dedicated attachment portion 127, and the lower cover 87 is provided with a claw 133 that engages with the lower dedicated attachment portion 129.

  In addition to the above, the opening edges of the upper and lower covers 85 and 87 are grooves, except for the vicinity of the rotating shaft, specifically, so that the outer peripheries of the upper cover 85 and the lower cover 87 are also brought into contact with each other. An L-shaped groove, more specifically, one of the upper cover 85 and the lower cover 87 has a fitting recess exposed to the outside, and the other has a fitting recess exposed to the inside, and is an L-shape that can be fitted to each other. Grooves are formed. In this way, the upper and lower covers 85, 87 adapted to engage with the upper and lower dedicated mounting portions 127, 129 of the support base 3 are arranged so as to cover the claw 131, 133 of the upper and lower covers 85, 87 while maintaining a position apart from the support base 3. The upper and lower covers 85 and 87 can be securely fitted to each other even if they are configured.

  The left and right front links 33 are rotatably attached via the front link shaft 29 to the bearing portion 45 in front of the support base 3 described above. The structure for attaching the front link 33 to the support base 3 is as follows. That is, as shown in FIGS. 5, 6, 9, 11, and 17, the support base 3 is perpendicular to the axial direction and the bearing 45 that supports the front link shaft 29 on the left and right. The front link 33 is located between the planes 137 in a rotation range in use where the original function of the chair can be exhibited, and the front link 33 is supported by the support base 3. In the insertion / removal rotation range that can be inserted / removed with respect to the rear surface, a flat-corresponding portion 139 located outside the flat surface 137 is provided. I am letting.

  In other words, as shown in FIG. 4 to FIG. 11, the support base 3 has a front bearing portion 45 that supports the front link shaft 29 and a position adjacent to the front bearing portion 45 in the axial direction. A link arm accommodating portion 141 opened upward is provided. The link arm accommodating portion 141 is formed between a pair of flat surfaces 137 orthogonal to the front link shaft 29. The front link 33 has a shaft hole 145 that holds the front connecting shaft 143 at the upper end portion, and a boss portion 147 that is externally mounted on the front link shaft 29 at the base end portion. A link arm 149 is provided. The link arm 149 has a plane corresponding portion 139 corresponding to the link arm accommodating portion 141. In the rotation range in use, the plane corresponding portion 139 of the link arm 149 is located between the opposing planes 137 of the link arm accommodating portion 141. Therefore, the left and right front links 33 are prohibited from being detached from the front link shaft 29 and the front connection shaft 143. On the other hand, in the rotation range at the time of insertion / removal, the plane-corresponding portion 139 of the link arm 149 is located outside the plane 137 facing the link arm accommodating portion 141. Therefore, the left and right front links 33 can be detached from the front link shaft 29 and the front connecting shaft 143. In the assembled state, the front link 33 is set so as not to rotate to the rotation range during insertion / removal.

  The seat base is supported by the support base 3 configured as described above via the front link 33 and the rear link 35.

《Composition of the seat》
As shown in FIGS. 2 to 4 and 11 to 17, the seat 5 has a form that can be referred to as an outer shell. In this embodiment, the seat 5 is integrally molded with a synthetic resin. On the lower surface of the seat 5, a front link attachment portion 153 for attaching the rotation end 151 of the front link 33 via the front connection shaft 143 and a rotation end 157 of the rear link 35 via the rear connection shaft 155 are provided. A rear link mounting portion 159 for mounting is provided. In addition, armrest mounting portions 165 having a plurality of screw holes 163 on a flat surface for mounting the armrest 161 are provided on both sides of the lower surface of the seat receiver 5. An operating lever 75 for adjusting locking and an operating lever 83 for raising and lowering are attached to a side portion of the seat receiver 5, more specifically, one side portion near the front of the seat receiver 5.

  Specifically, as shown in FIGS. 13 to 15, each of the operation levers 75 and 83 includes base end boss portions 169 and 171 that are rotatably mounted on a common shaft 167, and the base ends thereof are provided. Lever main bodies 173 and 175 are extended outward from the boss portions 169 and 171, and rotating arms 177 and 179 are protruded inward from the boss portions 169 and 171.

  As shown in FIGS. 13 to 15, the lever main bodies 173 and 175 are formed by smoothly cutting off the corners on the outer edge side, and both the operation levers 75 and 83 are externally attached to the common shaft 167 so as to be adjacent to each other. Accordingly, the lever main bodies 173 and 175 are arranged so as to form a substantially crescent shape in a plan view. Both the operation levers 75 and 83 can be attached to the seat receiver 5 by being inserted into the lever attachment window 181 provided on the side surface of the seat receiver 5 from the outside. That is, on both side edges of the lever mounting window 181, bearing portions 185 having elastic pieces 183 for retaining are provided on the inlet side, and both end portions 187 of the shaft 167 on which the operation levers 75 and 83 are extrapolated are provided. Are attached to the bearing portion 185 by utilizing the temporary elastic deformation of the elastic piece 183, so that these operation levers 75 and 83 are attached to the seat receiver 5. One end of a locking adjustment wire 77 for operating the locking state of the tilt lock mechanism 51 provided on the support base 3 is connected to the rotation arm 177 of the operation lever 75 for locking adjustment. One end of a lifting / lowering wire 81 for operating the lock state of the unlocking operation button provided on the leg column 17 is connected to the turning arm 179 of the operation lever 83.

  As shown in FIGS. 13, 15, and 16, reinforcing ribs 189 that run in the front-rear and left-right directions are provided on the upper surface of the seat receiver 5, and guidance for guiding the seat 7 in the front-rear direction. A mounting seat 193 for mounting the protrusion 247 is provided. A plurality of locking holes 195 for locking the seat 7 at a predetermined position in the front-rear direction are formed on the upper surface of the rear end portion of the seat receiver 5 at predetermined intervals in the front-rear direction.

《Composition of the seat》
As shown in FIGS. 1 to 4, 11, 13, 14, 16, and 17, the seat 7 has a tension material 199 stretched on the outer surface of the core member 197. The core material 197 includes an inner shell 201 and a cushion 203 disposed on the inner shell 201.

  As shown in FIGS. 4, 11, 13, 14, 16, and 17, the inner shell 201 is integrally formed of synthetic resin and is provided on the seat 5 so as to be movable back and forth. Yes. The inner shell 201 includes an intermediate portion 205 and a peripheral edge portion 207 that surrounds the intermediate portion 205. The inner shell 201 includes a front end hanging portion 209 that gently hangs obliquely downward on the front side of the peripheral edge portion 207, and the intermediate portion 205 An annular step portion 211 is formed at the boundary with the peripheral edge portion 207 so that the intermediate portion 205 bulges below the peripheral edge portion 207. Further, on the rear side of the peripheral portion 207, an opening 217 for a locking projection for projecting and retracting a locking projection 215 of a seat slide operating lever 213, which will be described later, and a seat slide operating lever 213 are provided. An opening 221 for an operation unit for exposing the operation unit 219 is provided. Further, in the vicinity of the opening 217 on the upper surface of the inner shell 201, a bearing portion 223 for pivotally mounting the seat slide operating lever 213 is provided.

  As shown in FIGS. 11, 13, 14 and 16, the cushion 203 is made of foamed urethane or the like, and includes a cushion hanging portion 225 along the front end hanging portion 209 of the inner shell 201 on the front side. Yes. The upper surface of the cushion 203 is provided with a plurality of concave and convex portions arranged in one direction, in other words, a plurality of grooves 227 arranged in the front-rear direction in this embodiment.

  As shown in FIGS. 11, 14, 16, and 17, the upholstery 199 is a bag that covers a part of the cushion 203 and the shell 201, that is, the peripheral edge 207 of the cushion 203 and the inner shell 201. The edge 229 of the stretch 199 wound around the lower surface side of the inner shell 201 is arranged along the end surface of the step portion 211 of the inner shell 201. In FIG. 14, half of the upholstery 199 is omitted.

  By attaching the seat 7 as described above to the seat receiver 5, as shown in FIGS. 14 and 15, when the seat 7 is viewed from the line of sight perpendicular to the seating surface, the locking adjustment and Only the tip portions 231 and 233 of the operating levers 75 and 83 for raising and lowering are visible. More specifically, the outer edges of the lever bodies 173 and 175 in the operation levers 75 and 83 in the plan view, more specifically, the acute angle portions 235 and 237 at the outer edges are hidden behind the seat 7 and cannot be seen. Therefore, it is possible to suppress the possibility that the clothes of the seated person will be caught on the acute angle portions 235, 237.

  The seat 7 is attached to the seat receiver 5 by a seat slide mechanism 239 so that the front-rear position can be adjusted.

<Configuration of seat slide mechanism>
As shown in FIGS. 11, 13, 14, and 16, the seat slide mechanism 239 includes a plurality of slits 241 provided in the inner shell 201 and extending in the front-rear direction, and a lower end provided through the slit 241. And a guide protrusion 247 that is attached to the mounting seat 193 of the seat receiver 5 and a wide portion 245 provided at the upper end is engaged with the opening end on the upper surface side of the slit 241, and the slit 241 and the guide protrusion The seat 7 can slide in the front-rear direction with respect to the seat receiver 5 within a range in which relative movement with respect to 247 is possible. Further, the seat slide mechanism 239 is provided on the inner shell 201, and is provided on the seat receiver 5 and a locking protrusion 215 provided on the seat slide operation lever 213 for operating the seat 7 that is an operation target. The seat 7 can be locked at a predetermined position in the front-rear direction by cooperation with the plurality of locking holes 195 formed.

  As shown in FIGS. 11, 13, 14, and 16, the seat slide operating lever 213 is a plate-like one in which the base end shaft portion 249 is rotatably supported by the bearing portion 223 of the inner shell 201. In addition, a locking projection 215 is provided on the lower surface of the intermediate portion, and an operation portion 219 protruding downward is provided on the lower surface of the rotating end 251, and the locking projection 215 is used for the locking projection of the inner shell 201. The operation portion 219 faces the lower surface of the inner shell 201 through the opening 221 for the operation portion. A leaf spring 253 elastically contacting the upper surface of the inner shell 201 is integrally provided on the base end shaft portion 249 of the seat slide operation lever 213, and the seat slide operation lever 213 is elastically biased by the leaf spring 253. Is biased in the direction in which the locking projection 215 protrudes from the opening. In a state where the seat slide operation lever 213 is not operated, the locking projection 215 protrudes from the lower surface of the inner shell 201 and engages with any locking hole 195 of the seat receiver 5 as shown in FIG. At the same time, the operating portion 219 of the seat slide operating lever 213 is set to be substantially flush with the lower surface of the inner shell 201.

  As shown in FIGS. 11, 13, 14, and 16, the operation unit 219 can be operated from the outside via a stretched fabric 199, and the operation unit 219 can be operated via the stretched fabric 199. A characteristic portion for recognition by touch, specifically, a concave portion 255 is formed. When the operation portion 219 of the seat slide operation lever 213 is pressed upward via the tensioned ground 199, the seat slide operation lever 213 is rotated upward, and the locking projection 215 is extracted from the locking hole 195. It is like that. Therefore, by appropriately operating the seat slide operation lever 213, the locking projection 215 can be selectively locked in the desired locking hole 195, and the front and rear sliding position of the seat 7 can be changed.

  Note that the edge 229 of the upholstery 199 is annularly arranged along the step portion 211 of the inner shell 201 as described above. However, the edge 229 is seated even if the seat 7 slides to any position. It is set so as not to be positioned outside the outer edge of the receiver 5 and is always hidden by the seat receiver 5.

<Configuration of back support arm>
As shown in FIGS. 1 to 5, 11, and 17 to 22, the left and right back support arms 9 are made of metal and are rotatably supported by the support base 3. Are provided with a shaft mounting portion 259 for fitting from the outside to the end portion 257 of the support shaft 31 provided on the support base portion 3, and an upward concave portion 261 for attaching the backrest 11 to the rear end portion 260. Have. Each back support arm 9 has a substantially L-shape in side view having a portion extending in the front-rear direction and a portion extending in the vertical direction.

  As shown in FIGS. 4, 5, 11, and 17 to 19, the shaft mounting portion 259 of each back support arm 9 is opened inward to fit the end portion 257 of the support shaft 31. A shaft hole 263 and a through hole 265 for inserting a screw that allows the bottom surface of the shaft hole 263 to communicate with the outside are provided. The through-hole 265 has a large-diameter portion 271 for accommodating the head 269 of the screw 267, and a guide surface 273 continuous with the large-diameter portion 271 of the through-hole 265 on the outer surface of the shaft mounting portion 259. It has. Then, the screw 267 inserted into the through hole 265 is screwed into a screw hole 278 formed in the end surface of the support shaft 31, so that the back support arm 9 is fixed to the support shaft 31. In a state where the screw 267 is fastened to the screw hole 278, the head 269 of the screw 267 is accommodated in the large diameter portion 271. In this embodiment, the guide surface 273 has a substantially spherical shape, and is set so as to be smoothly continuous with the tip surface 275 of the head 269 of the screw 267 accommodated in the large diameter portion 271.

  As shown in FIGS. 4, 5, 11, and 17 to 19, the rear link 35 and the torque transmission bracket 53 are held on the outer periphery of the shaft mounting portion 259 from the outside. A torque transmission projection 277 is provided integrally.

  As shown in FIGS. 4, 5, and 18 to 20, each back support arm 9 includes an inner standing portion 279 and an outer standing portion 281 that form the concave portion 261 in the rear end portion 260. is there. The inner upright portion 279 and the outer upright portion 281 are each raised upward from the bottom surface portion of the recess, and the height of the outer upright portion 281 is set to be larger than the height of the inner upright portion 279. ing. Further, on the front side of the inner standing part 279 and the outer standing part 281, there is provided a step having a contact part 288 with which the lower end part on the front side in the right and left side parts of the back frame 293 can contact.

  As shown in FIGS. 4, 5, and 18 to 20, the outer standing portion 281 includes an outer wall 283 that forms one inner surface of the recess 261, and an inward extension from the front edge of the outer wall 283. And a front wall 285 to be taken out. The height dimension of the outer wall 283 is set to be larger than the height dimension of the inner standing portion 279, and the outer walls 283 of the left and right back support arms 9 hold the both sides of the back frame 293. I am doing so. The front wall 285 is formed with a screw hole 287 into which a screw 307 as a fastening tool for attaching the backrest 11 is screwed. Each back support arm 9 includes a support portion 291 for supporting an end portion of a decorative plate 289, which will be described later, inside the rear end portion 260.

《Composition of backrest》
As shown in FIGS. 1 to 4 and FIGS. 18 to 22, the backrest 11 is a mesh having a back frame 293 and a strength that is attached to the back frame 293 and can receive a load from a seated person. The decorative plate 289 is provided on the lower edge of the back frame 293.

  As shown in FIGS. 1 to 4 and FIGS. 18 to 22, the back frame 293 has a frame shape and is integrally formed of resin. The left and right sides of the lower end 296 of the back frame 293 have protrusions 297 that protrude downward. That is, the lower end 296 of the back frame 293 has a recessed shape so as to form a U-shape when viewed from the back. Further, the back frame 293 is provided with a groove 299 that engages with the front wall 285 of the outer standing portion 281 provided at the rear end of the back support arm 9 from above and below. That is, the groove 299 opens outward and downward and extends vertically, and the protrusion 297 is integrally formed continuously from the lower end of the rear wall 301 forming the groove 299. . Further, a screw insertion hole 305 is provided in the front wall 303 forming the groove 299, and a screw 307, which is a fastening tool inserted into the screw insertion hole 305, is attached to the back support arm 9. The back frame 293 is fixed to the back support arm 9 by screwing into a screw hole 287 provided in the front wall 285.

  Further, as shown in FIG. 1 to FIG. 4 and FIG. 18 to FIG. 22, an attachment groove 309 for inserting and attaching the edge of the upholstery 295 is formed on the outer periphery of the back frame 293. Furthermore, a lumbar support attaching portion 313 for attaching a lumbar support device 311 described later is provided at an intermediate position in the vertical direction of the back frame 293.

  More specifically, as shown in FIGS. 1 to 4 and FIGS. 18 to 22, the back frame 293 includes left and right side frames 315, a lower frame 317 connecting the lower ends of these side frames 315, and The lumbar support attaching portion 313 is provided on the left and right side frames 315. The upper frame 319 connects the upper ends of the side frames 315. The lumbar support mounting portion 313 includes a guide groove 321 formed continuously in the vertical direction on the front surface of the side frame 315, and a plurality of moderation recesses formed at a predetermined pitch in the region adjacent to the inside of the guide groove 321. 323, and a pair of mounting screw holes 325 provided at positions on the upper and lower sides so as to sandwich the guide groove 321 and the moderation recess 323, respectively.

  As shown in FIGS. 1, 3 to 5, 18, 19, and 21, the decorative plate 289 covers an intermediate portion of the lower end 296 of the back frame 293 from the lower side. The decorative plate 289 is temporarily placed between the support portions 291 and the back frame 293 is attached to the back support arms 9 so that the back frame 293 can be attached to the back frame 293. In this attached state, both end portions 326 of the decorative plate 289 are sandwiched between the left and right back support arms 9 and the back frame 293.

  As shown in FIGS. 1, 3 to 5, 18, 19, and 21, the decorative plate 289 has an upward recess 327 that opens upward, and the back frame 293 and the upward recess A rib 329 provided at 327 is engaged. That is, ribs 329 for preventing lateral displacement are provided on the bottom surface 331 of the upward concave portion 327, and these decorative plates 289 are engaged by engaging these ribs 329 with ribs (not shown) provided at the lower end 296 of the back frame 293. The lateral displacement of the back frame 293 is prevented. In addition, ribs 333 for preventing rattling are provided on the inner side surface of the upward concave portion 327, and the tips of these ribs 333 are brought into contact with the front and rear surfaces of the back frame 293, thereby Shaking in the front-rear direction with respect to the back frame 293 is prevented.

  The backrest 11 configured as described above and the seat 7 are interlocked by a locking mechanism 13.

《Configuration of locking mechanism》
As shown in FIGS. 4, 11, and 12, the locking mechanism 13 is of a weight sensing type in which the seat 7 is moved upward while being tilted in accordance with the backward tilting motion of the backrest 11.

  More specifically, as shown in FIGS. 4, 11, and 12, the locking mechanism 13 includes a support base 3 that holds a front link shaft 29 on the front side and a support shaft 31 on the rear side, and a lower end portion. The front link 33 is rotatably supported on the support base 3 via the front link shaft 29, and the lower end portion is integrated with the shaft mounting portion 259 of the back support arm 9 supported by the support shaft 31. The rear link 35 and the front link attaching portion 153 are connected to the rotating end 151 of the front link 33 via the front connecting shaft 143 and the rear link attaching portion 159 is connected to the rear link 35 via the rear connecting shaft 155. The seat receiver 5 is connected to the rotating end 157 and is mainly configured.

  That is, as shown in FIGS. 4, 11, and 12, the locking mechanism 13 allows the seat base 5 that supports the seat 7 to be supported on the support base 3 by the front link 33 and the rear link 35 that are inclined in the same direction. In accordance with the backward tilting operation of the back support arm 9 supported by the support base 3, the front link 33 and the rear link 35 are rotated in the standing direction to lift the seat receiver 5 upward. It is of a weight sensing type, and is configured to lift the front part of the seat 7 more than the rear part of the seat 7 when the backrest 11 is tilted backward. That is, in the normal backrest and seat synchro-rocking mechanism, the seat is tilted only downward in accordance with the backward tilting motion of the backrest, but the weight sensing type locking mechanism as shown in this embodiment 13 is configured to lift the seat 7 against the load of the seated person while tilting the seat 7 in accordance with the backward tilting motion of the backrest 11, unlike a normal locking mechanism.

  More specifically, as shown in FIGS. 4, 11, and 12, when the backrest 11 is not tilted backward, the forward link 33 has a forward inclination of the rear link 35. It is set to be larger. In other words, when the backrest 11 is not tilted backward, the inclination angle α with respect to the horizontal line at the front link 33 is set smaller than the inclination angle β with respect to the horizontal line at the rear link 35. The rotation center of the front link 33 relative to the support base 3 is set at a position higher than the rotation center of the rear link 35 relative to the support base 3. In other words, the axis of the front link shaft 29 is set at a position higher than the axis of the support shaft 31 by a distance h. The effective length dimension of the front link 33, that is, the inter-center distance L1 between the front link shaft 29 and the front connecting shaft 143, and the effective length dimension of the rear link 35, that is, the support shaft that is the rear link shaft. The distance L2 between the shaft centers of 31 and the rear connecting shaft 155 is set to be substantially the same distance. Further, the back support arm 9 is pivotally supported by a portion of the support base 3 that is in front of the leg column 17. In other words, the shaft mounting portion 259 of the back support arm 9 is supported by the support shaft 31 positioned in front of the leg support 17 in a side view.

  The point that the forward inclination degree of the front link 33 is made larger than the forward inclination degree of the rear link 35 is for the purpose of lifting the front side of the seat 7 relatively larger than the rear side during the backward inclination. By making the forward tilting degree of the link 33 and the rear link 35 greatly different from each other, it is possible to set the lift of the front side of the seat 7 during the backward tilting to be large. In other words, the front link 33 often moves up the front part of the seat 7, that is, the front part of the seat surface, and the rear link 35 is mainly operated to move the seat 7 backward. As a result, the seat surface moves backward while the rear portion of the seat surface is lifted by a large amount, while the rear portion of the seat surface moves backward, and the backrest 11 tilts backward. As a result, the relative positional relationship between the rear end portion of the seat 7 and the lower end portion of the backrest 11 is effectively suppressed by tilting the seat surface relatively rearward.

  The point that the rotational center positions of the front link 33 and the rear link 35 are different in the vertical direction is mainly for the purpose of adjusting the level of the seat 7 when standing upright. By combining with the forward tilt degree difference, the posture of the seat 7 when the backrest 11 stands and the posture of the seat 7 when the backrest 11 is tilted backward are both set to an optimum state. By making the effective length dimension L1 of the front link 33 and the effective length dimension L2 of the rear link 35 substantially the same dimension, the setting is made more appropriate.

  In general, in a chair in which the back support arm is pivotally supported at a position in front of the leg column in the support base, the backrest tends to sink downward when the backrest is tilted. When using a normal weight-sensitive locking mechanism that allows the entire seat to lift upward when tilted backwards, the rear part of the seat is more discomfort, more specifically, contrary to the seated person's expectation. As a result of lifting the entire seat including the upper part of the seat, there is a sense of incongruity that is given by the simultaneous movement of the backrest sinking motion and the seat lifting motion opposite to the sinking motion in the vicinity of the waist of the seated person, According to the configuration of the present embodiment, the uncomfortable feeling is alleviated. That is, although the thing of this embodiment is a body weight sensing type, even when the backrest 11 is tilted backward, the rear side of the seat 7 is not lifted greatly, so that it is difficult to give a great sense of incongruity.

  Further, in the present embodiment, the rotation range of the backrest 11 is set to 20 degrees, and the angle formed by the seating surface in a state where the backrest 11 is tilted backward as much as possible is 4 compared to when the backrest 11 stands. It is set to tilt backward. That is, in this embodiment, when the backrest 11 is tilted backward by the front link 33 rather than the dimension in which the rear portion of the seat surface is lifted mainly by lifting the substantially central portion of the seat 5 when the backrest 11 is tilted backward by the rear link 35. As a result of setting the dimension for raising the front part of the seat back to be larger, the angle of the seat face when the backrest 11 is tilted to the maximum is tilted back by 4 degrees than when the backrest 11 is upright. In addition, in the present embodiment, since the rear link 35 is connected to the substantially central portion in the front-rear direction of the seat receiver 5, the front receiver 33 is lifted together with the front and rear links 33 and 35 when the backrest 11 is tilted backward. However, since the front link 33 lifts the seat receiver 5 more than the rear link 35, the rear end portion of the seat receiver 5 can be set relatively lower than the front end portion, and the front end portion of the seat receiver 5 is raised. When doing so, the height position of the rear end portion of the seat rest 5 is hardly changed between when the backrest 11 stands and when it tilts backward.

<Configuration of lumbar support device>
As shown in FIGS. 21 and 22, the lumbar support device 311 is installed between the left and right back frames of the backrest 11, that is, between the side frames 315 of the back frame 293. The lumbar pad 335 and the lumbar An airbag 337 for moving the pad 335 forward and backward to change the pressure receiving state at the waist of the backrest 11, a pump 339 for supplying air to the airbag 337, and a lumbar support operation for operating the pump 339 The lever 341 is attached to a common base 343 and unitized. In other words, the lumbar support device 311 includes a lumbar pad 335 and a lumbar base 345 that supports the lumbar pad 335. The lumbar base 345 includes the airbag 337, the pump 339, and the lumbar support operating lever. 341 is supported by a common base 343. The lumbar base portion 345, both end portions 347, and the left and right side frames 315 form a gap 349 that is open in the three directions of the backrest 11 in the right or left outer direction and the vertical direction.
The lumbar base 345 is provided so that the vertical position of the lumbar base 345 can be changed.

  More specifically, as shown in FIGS. 21 and 22, the base 343 has an elongated frame shape on the left and right, and an intermediate shaft 344 with the lumbar support operating lever 341 extending in a substantially vertical direction at one end thereof. It is attached so that it can rotate in the front-rear direction. At both ends of the front edge of the base 343, mounting arms 351 that engage with the lumbar support mounting portions 313 of the side frame 315 are projected. The left and right mounting arms 351 are arranged so as to wrap around the front side of the side frame 315, and on the rear side thereof, a slide pin 353 slidably engaged with the guide groove 321 of the lumbar support mounting portion 313, and the moderation A moderation convex portion 355 that selectively engages with the concave portion 323 is provided. Further, a mounting plate 357 functioning as a leaf spring is arranged on the front side of both the mounting arms 351, and the mounting plate 357 is connected to the screw hole 325 of the lumbar support mounting portion 313 using a screw 361. By attaching to the front surface of the frame 315, the lumbar support device 311 is held with respect to the back frame 293 so that the vertical position can be adjusted. The base 343 accommodates a pump 339, a release valve 363, a release arm 365, and a release spring 367, respectively, and an airbag assembly 371 is disposed on the front surface of the base 343 via a spacer 369. Has been. The airbag assembly 371 includes the airbag 337 and a pipe 373 that connects the airbag 337 and the pump 339.

  As shown in FIGS. 22 to 24, the pump 339 is of a type called a grip hand pump, and the lumbar support operation lever 341 is operated by rotating the lumbar support operation lever 341 forward, that is, forward of the chair. The compressed air is compressed by the proximal end pressing arm 375 of 341, and the air is discharged toward the airbag 337. The proximal end pressing arm 375 has a convex shape toward the pump 339 in order to efficiently deform the intermediate portion of the pump 339 into a concave shape.

  As shown in FIGS. 22 to 24, the release valve 363 is for releasing the air in the airbag 337 to the outside. It can be opened to

  As shown in FIGS. 22 to 24, the release arm 365 is pivotally attached to the base 343 via the rotary shaft 380 so that the base end 379 can be rotated in the front-rear direction, and the intermediate portion 381 is operated to release the release valve 363. The distal end portion 383 faces the button 377 and is positioned in front of the proximal end pressing arm 375. Here, the intermediate portion 381 protrudes in a direction toward the release operation button 377 so that the release operation button 377 can be surely pressed. Then, by rotating the operation end 342 side of the lumbar support operation lever 341 backward, that is, toward the rear of the chair and pressing the front end 383 of the release arm 365 forward, the intermediate portion 381 of the release arm 365 is operated. Thus, the release operation button 377 of the release valve 363 can be pressed.

  As shown in FIGS. 22 to 24, the release spring 367 is for self-returning the release arm 365 to the original standby position when the operating force of the lumbar support operating lever 341 is deenergized.

  As shown in FIGS. 22 to 24, the back surface of the lumbar support operating lever 341 is recessed so as to be opened rearward, in other words, recessed rearward, in order to facilitate the operation of pressing toward the front. It has a shape. Furthermore, it can be said that it is a concave shape opening rearward. Further, as shown in FIGS. 22 to 24, the front surface of the lumbar support operating lever 341 is also recessed so as to open forward, in other words, recessed forward, so as to facilitate the operation of pushing backward. The shape to make. Furthermore, it can be said that it is a concave shape opening forward. That is, the thickness dimension of the portion closer to the operation end 342 than the intermediate shaft 344 of the lumbar support operation lever 341 becomes smaller as it approaches the center in the width direction. Further, a gap 349 having a sufficient size as a movable region for moving the lumbar support operation lever 341 forward is provided between the lumbar support operation lever 341 and the side frame 315. It is arranged so that it can be operated with one hand by placing a thumb on the front side and another finger on the back side of the operation lever.

  Here, as shown in FIG. 23, the lumbar support operating lever 341 rotates and moves around the intermediate shaft 344 when a forward operation, which is an operation of the first mode, is applied to the operation end 342 side. Thus, the base end pressing arm 375 moves backward while being separated from the distal end portion 383 of the release arm 365 while leaving the distal end portion 383 of the release arm 365 at the initial position. At this time, the proximal end pressing arm 375 presses and operates the pump 339. In addition, as shown in FIG. 24, the lumbar support operating lever 341 rotates around the intermediate shaft 344 when the operation of the second mode is applied to the operation end 342 side. The proximal end pressing arm 375 moves forward, and the proximal end pressing arm 375 moves the distal end portion 383 of the release arm 365 forward. At this time, the release valve 363 rotates about the rotation shaft 380 provided at the base end 379, and the intermediate portion 381 also moves forward along with this, and the release operation button 377 of the release valve 365 is pressed to be opened. And In this manner, the common lumbar support operation lever 341 can realize two functions, that is, a function of supplying air to the airbag 337 and a function of releasing the air of the airbag 337 to the outside.

《Arrangement of armrest》
As shown in FIGS. 1 to 4 and 14, the chair includes a pair of armrests 161 provided from the lower surface of the seat receiver 5 toward the upper left and right. Each armrest 161 has an elbow post 385 having a base end portion attached to the armrest attachment portion 165 of the seat 5, an elbow support portion 387 provided at the upper end of the elbow support 385, and is supported by the elbow support portion 387. And an elbow rest 389. A plurality of elongated holes 393 for inserting bolts are formed in the base end portion 391 of the elbow strut 385. The long hole 393 extends in the left-right direction. Then, when the base end portion 391 of the elbow post 385 is attached to the armrest attaching portion 165 of the seat 5, the relative position of the bolt 395 with respect to the elongated hole 393 is changed, so that the left and right positions of the armrest 161 are set within a predetermined range. It can be changed with. In FIGS. 11 and 17, the armrest 161 is omitted.

  As described above, in the chair according to the present embodiment, the backrest 11 includes the back frame 293 having the protruding portions 297 downward on the left and right sides of the lower end 296, and the back support arms 9. However, each of the rear end portions 260 has an upward concave portion 261, and both the projecting portions 297 are fitted into the concave portions 261 of the both back support arms 9, respectively, and the back frame 293 is fitted into the both support arm 9. Therefore, the back frame 293 of the backrest 11 is fitted and held from the upper side to the rear ends of the left and right back support arms 9, and an appropriate fastening operation can be performed in this state. In addition, since the protrusions 297 are fitted and supported in the recesses 261 of the back support arm 9, the contact area between the back support arm 9 and the back frame 293, in other words, the back support arm. 9 can secure a large support range for supporting the back frame 293, and the back support arm 9 and the back frame 293 can be securely held.

  A decorative plate 289 that covers an intermediate portion of the lower end 296 of the back frame 293 from below is provided, and the left and right back support arms 9 include support portions 291 for supporting end portions of the decorative plate 289, respectively. The decorative plate 289 can be attached to the back frame 293 by installing the decorative plate 289 in a temporarily placed state between the support portions 291 and attaching the back frame 293 to the back support arms 9. Thus, the decorative plate 289 can be reliably attached without increasing the number of assembling steps and without being displaced.

  The chair in this embodiment is arranged on the leg 1 provided with leg blades 19, the support base 3 supported by the leg 1 and rotatably supporting the left and right back support arms 9, and the support base 3. The seat 7 and the locking mechanism 13 that moves the seat 7 in accordance with the backward tilting motion of the backrest are provided. Even in such a configuration, the back support arm 9 and the back support arm 9 are also provided. If the attachment structure with the frame 293 is applied, interference between the back support arm 9 and the seat 7 or the seat receiver 5 can be suitably avoided. In particular, in the present embodiment, the locking mechanism 13 is of a weight sensing type configured such that the seat 7 and the seat receiver 5 are moved upward as the backrest 11 is tilted backward. By adopting the mounting structure of the back support arm 9 and the back frame 293 according to the embodiment, the interference between the back support arm 9 and the seat 7 and the seat receiver 5 due to the backward tilting operation is suitably suppressed.

  Since both end portions 326 of the decorative plate 289 are sandwiched between the left and right back support arms 9 and the back frame 293, the decorative plate 289 can be easily attached.

  The left and right back support arms 9 are each provided with an inner standing portion 279 and an outer standing portion 281 that form the concave portion 261 at the rear end portion 260, respectively. Since the back frame 293 fitted with the projecting portions 297 is fixed to the outer standing portion 281 of each of the back support arms 9 via a fastener, the back frame 293 is securely attached to the support arm 9. Can be attached to.

  Since the lower end 296 of the back frame 293 is recessed so as to form a U shape when viewed from the back, even if the backrest 11 is tilted rearward, the vicinity of the center of the lower end 296 of the back frame 293 is a leg blade. 19, and interference with a load placed near the leg blades 19 can be suitably suppressed.

  Each back support arm 9 includes an inner standing portion 279 and an outer standing portion 281 that form the concave portion 261 at the rear end portion 260, respectively, and the height dimension of the outer standing portion 281 is the height of the inner standing portion 279. Since it is set larger than the size, it can be held so as to hold both sides of the back frame 293, and the back frame 293 can be securely held to the back support arm 9.

  In addition, a step having an abutting portion 288 with which the front lower end portions of the left and right sides of the back frame 293 can abut is provided on the front side of the inner standing portion 279 and the outer standing portion 281. The back frame 293 can be attached to the back support arm 9 without shifting the horizontal and vertical positions.

  The height dimension of the outer wall 383 is set to be larger than the height dimension of the inner upright portion 279, and is held by the outer walls 283 of the left and right back support arms 9 with both side surfaces of the back frame 293 sandwiched therebetween. As a result, the back frame 293 can be reliably held against the back support arm 9.

  The present invention is not limited to the embodiment described in detail above.

  The back support arm in the present embodiment is made of metal, but is not limited thereto. For example, resin, wooden, and other various types can be applied.

  The back frame of the backrest in the present embodiment is made of resin, but is not limited to this. For example, a metal thing, a wooden thing, and other various things are applicable. Further, the shape of the back frame is not limited as long as it has an upward U-shape.

  The chair in the present embodiment is provided with a seat slide mechanism and a lumbar support device, but it is needless to say that an aspect without these mechanisms and devices may be provided.

  The chair in this embodiment is provided with an armrest, but an aspect in which no armrest is provided is also conceivable.

  The chair in the present embodiment uses a weight sensing type locking mechanism as the locking mechanism, but it is needless to say that the present invention is not limited to this.

  In the present embodiment, the main frame of the support base has been described as the boss portion, the rear frame member, the side frame member, and the front frame member are integrally formed by aluminum die casting or the like, but the present invention is not limited thereto. Various things are conceivable. For example, the boss, rear frame member, side frame member, and front frame member, which are the constituent members of the main frame, are divided into a plurality of parts by bending or drawing a sheet metal material, and the front and rear bearings You may employ | adopt bearing parts etc. and connect them by welding etc., and you may comprise.

  In the present embodiment, as a structure for attaching a decorative plate, which is an erection part that covers the intermediate portion at the lower end of the back frame from the lower side, the left and right back support arms each have a support portion for supporting the end portion of the decorative plate. Although it was provided, the decorative plate was laid between the support parts in a temporarily placed state, and the back frame was attached to both back support arms so that the decorative plate could be attached to the back frame. Such a structure for attaching the erected parts can be applied to various structures.

  That is, the installation part to be attached is placed on a first member that is separate from the installation part and temporarily placed, and then the second member that is separate from the installation part is By attaching to one member, the installation part can be attached without detaching from the member. According to the structure for attaching such a construction part, it is also possible to attach the construction part without using a fastener. In addition, as such a construction part, as a thing applied to a chair, for example, a construction part provided between the backrest and the back support arm, a construction part provided between the back support arm and the support base, A construction part provided between the support base and the leg, a construction part provided between the armrest and the seat rest, a construction part provided between the backrest and the headrest, and the like are conceivable. In addition to the chair, the structure for attaching the erected parts can be applied to furniture such as panels.

  In the present embodiment, the effective length dimension L1 of the front link 33 and the effective length dimension L2 of the rear link 35 are set to be substantially the same size, so that the seat posture when the backrest is standing and the seat when the backrest is tilted backward. However, the above-described setting may be performed by making the effective length dimension L1 of the front link 33 larger than the effective length dimension L2 of the rear link 35.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Leg 3 ... Support base 7 ... Seat 9 ... Back support arm 11 ... Backrest 13 ... Locking mechanism 279 ... Inner standing part 281 ... Outer standing part 289 ... Decorative plate 291 ... Support part 293 ... Back frame 296 ... Lower end 297 ... Protruding part 327 ... concave part (upward concave part)
329 ... Ribs (ribs for preventing lateral displacement)
333 ... Rib (rib for preventing rattling)

Claims (9)

A chair with a backrest attached to left and right back support arms extending in the front-rear direction,
The backrest is provided with a back frame having downward projections on the left and right sides at the lower end, and each back support arm has an upward recess at the rear end, The projecting portions are fitted into the recesses of the back support arms, respectively, and the back frame is supported by the back support arms ,
A chair characterized in that a lower end of the back frame has a recessed shape so as to form a U-shape downward in a rear view . It includes a decorative plate that covers an intermediate portion at the lower end of the back frame from the lower side, and the left and right back support arms each include a support portion for supporting an end portion of the decorative plate, The chair according to claim 1, wherein the decorative plate is attached to the back frame by installing the decorative plate between support portions and attaching the back frame to the back support arms. It includes a decorative plate that covers an intermediate portion at the lower end of the back frame from the lower side, and the left and right back support arms each include a support portion for supporting an end portion of the decorative plate, The chair according to claim 1 or 2, wherein the decorative plate is attached to the back frame by installing the decorative plate in a temporarily placed state between the support portions and attaching the back frame to the back support arms. . The chair according to claim 2 or 3, wherein both ends of the decorative plate are sandwiched between the left and right back support arms and the back frame. A leg provided with leg blades, a support base supported by the leg for pivotally supporting the left and right back support arms, a seat disposed on the support base, and the seat tilted backward from the backrest The chair according to claim 1, 2, 3, or 4, further comprising a locking mechanism that operates in accordance with the operation. The chair according to claim 5, wherein the locking mechanism is of a weight sensing type configured such that the seat moves up with a backward tilting operation of the backrest. The chair according to claim 2, 3, or 4, wherein the decorative plate has an upward concave portion that opens upward, and the back frame engages with a rib provided in the upward concave portion. The left and right back support arms are each provided with an inner standing portion and an outer standing portion that form the recess at the rear end, and the protrusions are fitted in the recesses of the left and right spin support arms, respectively. The chair according to claim 1, 2, 3, 4, 5, 6 or 7, wherein a back frame is fastened to an outer standing part of each back support arm via a fastening tool. The outer standing portion includes an outer wall forming one inner surface of the recess, and a front wall extending inward from a front edge of the outer wall, and the back frame includes the front wall and the front wall. The chair according to claim 8, wherein a groove for fitting from above and below is provided.

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