JP5789753B2 - Chair - Google Patents

Description

  The present invention relates to a chair having a synchro-rocking mechanism in which a backrest and a seat used in an office operate in conjunction with each other.

  2. Description of the Related Art Conventionally, various chairs that are suitably used in offices or the like have been proposed that have a so-called synchro-rocking mechanism that can move the seat as the back leans backward.

  In recent years, a type in which a seated person whose back is tilted back can sit deeply into a chair by lowering the rear end of the seat with back tilt is often used.

  On the other hand, apart from the above-mentioned type, it is possible to lift the back end of the seat using the load applied to the backrest when the backrest is tilted backward, and the seated person can take a relaxed posture with the body extended. Many types of chairs have also been used in the past. This type of chair is, for example, referred to as “weight sensing type”, and the greater the load from the seated person on the rear end of the seat, the greater the force required to tilt the backrest backward. Therefore, the tilting reaction force of the backrest according to the weight of the seated person can be given (for example, refer to Patent Document 1).

  In recent years, in offices, desk work performed by a seated person is handled with the backrest upright, for example, operating a personal computer while looking at a display positioned in front of the desk. A method of using a chair has been accepted in which the work to be performed is performed with the backrest tilted backward. And it is desirable for these deskwork to be able to move smoothly without a sense of incongruity for the seated person.

  However, the above-described “weight sensing type” lifts the seat while maintaining the angle of the seat surface, or raises only the rear end portion of the seat at the same time when the backrest is tilted backward. Thus, when the backrest is tilted backward, the seated person takes a posture in which the entire body is unexpectedly extended due to an increase in the angle formed by the upper body and the thigh. For this reason, the seated person may be forced to change his / her posture and feel uncomfortable, making it difficult to continue desk work smoothly.

International Publication WO00 / 074531 Pamphlet

  An object of the present invention is to provide a chair that can continue desk work without a sense of incongruity even if a seated person changes his / her posture by standing up and leaning back.

  In order to achieve such an object, the present invention takes the following measures.

  That is, the chair according to the present invention has a seat supporting the seat supported directly or indirectly on the support base by the front link and the rear link inclined in the same direction, and the back support arm supported by the support base. A chair having a weight-sensing locking mechanism configured to rotate the front link and the rear link in an upright direction in accordance with a tilting operation to lift the seat support upward, Sometimes the front part of the seat is configured to be lifted more than the rear part of the seat.

  Here, “lifting up the seat” does not only include a mode in which all the lower region of the seat is lifted, for example, the rear end of the seat is slightly lowered. This is also a concept that refers to an aspect that can contribute to the weight sensing type by partially raising the portion of the seat where the load of the seated person is applied.

  In such a case, when the backrest is tilted backward, the front part of the seat is lifted up a lot, so the seat is tilted relatively rearward and the lower end of the backrest and the rear end of the seat are relatively The change in the positional relationship can be suppressed as compared with the conventional weight sensing type. In addition, by doing this, the vertical misalignment of the backrest portion located on the rearward extension line of the seating surface when the backrest stands and tilts backward is suppressed. As a result, the seated person is restrained from being forced to change his posture due to the back leaning. Therefore, even if the work at the time of standing up and leaning back is frequently switched, the desk work can be continued smoothly without causing a sense of incongruity.

  In addition, as a configuration for greatly lifting the front part of the seat, first, when the backrest is not tilted backward, the forward link is inclined so that the forward inclination degree of the front link is larger than the forward inclination degree of the rear link. Is mentioned. As a result, the direction of the locus tangent on the circumference drawn by the rotation operation of the front link is made closer to the vertical direction, so that the front link can be moved up more greatly even if the front and rear links are rotated by the same angle.

  On the other hand, by setting the effective length dimension of the front link larger than the effective length dimension of the rear link, a chair that lifts the front part of the seat more than the rear part of the seat can be realized.

  And, in order to lift the front part of the seat greatly, the forward link forward tilt degree is set to be larger than the forward link forward tilt degree, and the center of rotation of the front link with respect to the support base part is set as the support base part of the rear link. As a configuration that can be further applied to the aspect of setting the position higher than the rotation center with respect to the configuration, a configuration in which the effective length dimension of the front link is set larger than the effective length dimension of the rear link can be mentioned.

  On the other hand, a configuration in which the effective length dimension of the front link is set larger than the effective length dimension of the rear link, and the rotation center of the front link with respect to the support base is positioned higher than the rotation center of the support base of the rear link. Even in combination with the configuration to be set, the front part of the seat can be lifted more than the rear part of the seat.

  Here, in the case where the back support arm is a chair pivotally supported on the front portion of the support base, the entire backrest tends to descend when the backrest is tilted backward, and The backrest tilts backward just by hanging, making it easy to tilt backward and making it comfortable to sit on. However, the weight-sensing structure described in Patent Document 1 described above was applied to such a chair. However, when the backrest is tilted backward, the position of the lower end of the backrest and the rear end of the seat move up and down, and if the view is changed, the direction of the seat relative to the lower end of the backrest will also shift. The above-mentioned uncomfortable feeling becomes a big chair. Therefore, as in the present invention, when a weight sensing system configured to lift the front part of the seat more than the rear part of the seat when the backrest is tilted backward is applied, the backrest is accompanied by the backward tilt. The separation between the lower end portion of the backrest and the rear end portion of the seat or the displacement of the direction can be effectively suppressed. In other words, the seat is tilted relatively backward, and the change in the relative positional relationship with the lower end of the backrest is suppressed compared to the conventional weight-sensing type so that the seated person feels uncomfortable. It is possible to change the posture in which it is difficult to occur.

In order to effectively reduce the number of movable parts related to the backrest and the seat, the present invention provides a connecting shaft between the rear link and the seat support that is more than a support shaft that is a center of rotation of the rear link with respect to the support base. The rear link is integrally formed with a back support arm that supports the backrest so as to be positioned in the front, and the front link is configured separately from the back support arm.

  As a configuration for effectively reducing the number of parts for supporting the backrest and the seat while effectively using the tilting reaction force of the backrest, and further making the tilting reaction force generation mechanism compact, A torque transmitting member that compresses the elastic member when the back is tilted at the projected tip portion is provided so as to protrude forward and downward from the rearward tilt shaft portion of the forward front end portion of the support arm. And the structure which a torque transmission member operate | moves integrally can be mentioned.

  Further, when applying the present invention in which the seat is tilted relatively backward, if the rear link supports the substantially center in the front-rear direction of the seat, it is avoided to arrange the rear link near the rear end of the seat. By doing so, a space can be effectively secured in the vicinity of the rear end portion of the seat, and the design flexibility of the back support arm and the support base can be effectively improved.

  According to the present invention, the occupant is restrained from changing the posture caused by the backward leaning of the backrest.Therefore, even if the work is frequently switched between the standing posture and the backward leaning state, the seated person feels uncomfortable. It is possible to provide a chair that can continue desk work smoothly without occurring.

The perspective view from the front which shows one Embodiment of this invention. The perspective view from the front which decomposes | disassembles and shows the tension ground of the embodiment. The front which abbreviate | omits and shows the tension place of the embodiment partially. The left view which decomposes | disassembles and shows the tension ground of the embodiment. The rear view which abbreviate | omits and shows the tension place of the embodiment partially. The perspective view from the back which abbreviate | omits and shows the leg of the embodiment. The disassembled perspective view which abbreviate | omits and shows a part of the whole embodiment. The perspective view from the front which expands and shows the principal part of the support base and back support arm of the embodiment. The disassembled perspective view which expands and shows the principal part of the support base of the same embodiment, and a back support arm. The perspective view from the back which abbreviate | omits and shows the support base part of the embodiment abbreviate | omitting. The front view which decomposes | disassembles and shows the support base part of the embodiment. The left view which shows the support base and seat of the embodiment. Explanatory drawing equivalent to FIG. 12 which shows the locking mechanism of the embodiment. The disassembled perspective view which shows the seat and seat receiver of the embodiment. Sectional view on the AA line which showed the principal part in FIG. BB sectional drawing which showed the principal part in FIG. CC sectional view which showed the principal part in FIG. The perspective view which showed the attachment structure of the backrest support body and back support member of the embodiment. The perspective view which decomposes | disassembles and shows the back shell and back support member of the embodiment. The front view of the back shell of the embodiment. The front view of the back support member of the embodiment. DD line sectional drawing which showed the principal part in FIG. EE sectional view which showed the principal part in FIG. The FF line expanded sectional view in FIG. The GG sectional view taken on the line in FIG.

  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 7, 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 9 that is rotatably supported by the support base 3, the back 11 attached to the back support 9, and the back tilting operation of the back 11 are performed. And a rocking mechanism 13 for moving the seat receiver 5 and the seat 7 upward and downward, and an armrest 15 provided on the backrest support 9.

《Leg composition》
As shown in FIGS. 1 to 7, the leg 1 includes a leg base 17 and a leg support 19 provided at the center of the leg base 17.

  As shown in FIG. 1 to FIG. 5 and FIG. 7, the leg base 17 is provided with a plurality of leg blades 23 radially projecting from a hub 21 provided in the center portion. 25 are provided.

  As shown in FIGS. 1 to 5, 7, and 14, the leg support 19 is a gas spring type that is elastically expanded and contracted in the vertical direction so that it can be locked at a desired position. belongs to. That is, the leg support 19 includes a gas spring main body 27 fitted to the hub 21 of the leg base 17 and a rod 29 protruding from the upper end of the gas spring main body 27. An operation button 31 for unlocking is projected. The support base 3 is attached to the upper end of the rod 29. The unlocking operation button 31 is operated by an elevating operation lever 295 provided on an armrest 15 described later.

《Support base configuration》
As shown in FIGS. 7 to 13, the support base 3 includes a main frame 33 attached to the rod 29 of the leg support 19, and a front link shaft 35 and a support shaft 37 attached to the main frame 33. It will be. The front link shaft 35 is for supporting the front end portion of the seat receiver 5 through the front link 39. The support shaft 37 supports the backrest support body 9 including the back support arm 19 so as to be rotatable at a position in front of the leg column 19 and is also a middle portion of the seat 7 via the rear link 41. It is for supporting the substantially middle part.

  As shown in FIGS. 7 to 13, the main frame 33 has a boss portion 43 fitted to the upper end portion of the rod 29 in the leg support 19 and a semicircular arc shape in plan view surrounding the upper end side of the boss portion 43. The rear frame member 45, a pair of side frame members 47 extending forward from the left and right front ends of the rear frame member 45, and the front end portions of the side frame members 47 are coupled to each other and have a flat surface at the front end. A front frame member 49 is provided. The boss portion 43, the rear frame member 45, the side frame member 47, and the front frame member 49 are integrally formed by aluminum die casting or the like. A front bearing portion 51 that supports the front link shaft 35 is integrally provided on the upper surface portion of the front frame member 49, and the support shaft is located near the boundary between the rear frame member 45 and the side frame member 47. A rear bearing portion 53 that supports 37 is integrally provided. In addition, the height from the floor surface of the shaft center of the two bearing portions 51 and 53 is different, and the front bearing portion 51 is set at a higher position than the rear bearing portion 53.

  As shown in FIG. 12, the main frame 33 incorporates a tilt reaction force generation mechanism 55 that biases the backrest 11 forward.

  As shown in FIGS. 8 to 13, the tilt reaction force generating mechanism 55 includes a torque transmission bracket 57 which is a torque transmission member according to the present invention and has a pair of left and right base ends supported by the support shaft 37. And a movable shaft 59 installed between the tip portions of the left and right torque transmission brackets 57, and a spring 63 that elastically biases the movable shaft 59 backward as a scaffolding provided on the main frame 33. Do it. Reference numeral 64 designates a lifting / lowering unlocking arm for pressing the unlocking operation button 31 provided on the rod 29 of the leg post 19, and as shown in FIGS. , A lifting wire for transmitting the operating force of the lifting control lever 295 provided on the armrest 15 to the lifting lock release arm 64. When the wire 297 is pulled by operating the operation lever 295, the base end boss portion 66 externally fitted to the support shaft 37 rotates and is provided integrally on the opposite side of the wire 297 across the base end boss portion 66. The unlocked arm 64 is rotated downward.

  The support base 3 is covered with an upper cover 65 and a lower cover 67 as shown in FIGS. 3 to 6, 10, and 11.

  As shown in FIGS. 10 and 11, the upper cover 65 covers the support base 3 from the upper surface side, and is provided with an upper locking claw 69 protruding downward to engage with the support base 3. The lower cover 67 covers the support base 3 from the lower surface side, and is provided with a lower locking claw 71 protruding upward to engage with the support base 3. Further, the upper cover 65 and the lower cover 67 are arranged so that the opening end edges 73 and 75 abut each other.

  On the outer peripheral surface of the front side of the main frame 33 of the support base 3, in other words, on the flat surface of the front end of the front frame member 49, as shown in FIGS. And a common upper / lower mounting portion 77 for mounting the upper and lower sides.

  More specifically, the main frame 33 of the support base 3 includes an upper locking claw 69 of the upper cover 65 and a lower locking claw 71 of the lower cover 67, as shown in FIGS. An upper and lower common mounting portion 77 for engaging is provided, and the upper and lower common mounting portion 77 is engaged with an engagement end surface 79 with which the upper locking claw 69 is engaged and with the lower locking claw 71. An end face 81, a locking end face 83 for preventing lateral shift for locking lateral shift of the upper locking claw 69, and a locking end face 85 for preventing lateral shift for locking lateral shift of the lower locking claw 71 are provided. Yes.

  As shown in FIGS. 8, 10, and 11, the upper and lower common mounting portion 77 is provided on the outer peripheral surface 87 of the front end of the front frame member 49 in the main frame 33, and the outer peripheral surface 87 of the front end is rectangular. It is recessed in the shape. In the upper and lower mounting part 77, the upper side is an engagement end surface 79 with which the upper locking claw 69 of the upper cover 65 is engaged, and the lower side is an engagement end surface 81 with which the lower locking claw 71 of the lower cover 67 is engaged. Further, in the upper and lower common mounting portion 77, the left and right sides are locking end surfaces 83 and 85 for preventing lateral displacement with respect to the upper locking claw 69 and the lower locking claw 71 of the upper cover 65 and the lower cover 67.

  Note that, in the vicinity of the middle in the front-rear direction on the outer periphery of the main frame 33, as shown in FIGS. 8 to 10, 12, and 13, an upper dedicated mounting portion 89 for mounting the upper cover 65 and a lower cover 67 are mounted. And a lower dedicated mounting portion 91. The upper cover 65 is provided with a claw 93 that engages with the upper dedicated mounting portion 89, and the lower cover 67 is provided with a claw 95 that engages with the lower dedicated mounting portion 91.

  Further, as shown in FIG. 10, an upper dedicated mounting portion 97 for mounting the upper cover 65 and a lower dedicated mounting portion 99 for mounting the lower cover 67 are provided at the rear end of the outer periphery of the main frame 33. Yes. The upper cover 65 is provided with a claw 101 that engages with the upper dedicated mounting portion 97, and the lower cover 67 is provided with a claw 103 that engages with the lower dedicated mounting portion 99. In other words, the rear frame member 45 of the main frame 33 includes a substantially horizontal central protrusion that is the lower dedicated mounting portion 99 and a pair of upper dedicated mounting portions 97 disposed on both sides of the lower dedicated mounting portion 99. Side ridges are provided. The upper dedicated mounting portion 97 is arranged with a height different from that of the lower dedicated mounting portion 99.

  In addition to the above, the opening edges 73 and 75 of the upper and lower covers 65 and 67 are provided with grooves, except for the vicinity of the rotating shaft, so that the outer peripheries of the upper cover 65 and the lower cover 67 are also brought into contact with each other. Specifically, one of the upper cover 65 and the lower cover 67 has a fitting recess exposed to the outside, and the other has an L-shaped groove that can be fitted to each other with the fitting recess exposed to the inside. . In this way, the upper and lower covers 65, 67 adapted to engage with the upper and lower dedicated mounting portions 89, 91 of the support base 3 are arranged so as to cover the claws 93, 95 at a certain distance from the support base 3. Even if it has comprised, upper and lower covers 65 and 67 can be reliably fitted.

  The left and right front links 39 are rotatably attached to the bearing portion 51 in front of the support base 3 described above via the front link shaft 35. The structure for attaching the front link 39 to the support base 3 is as follows. That is, as shown in FIGS. 8 to 13, the support base 3 includes a bearing portion 51 that supports the front link shaft 35 on the left and right sides, and a pair of opposed flat surfaces 105 that are perpendicular to the axial direction. The front link 39 is located between the planes 105 in the rotation range (U) when used so that the chair can perform its original function, and the front link 39 can be inserted into and removed from the support base 3 (not shown). In the rotation range at the time of insertion / removal, a plane corresponding portion 107 located outside the plane 105 is provided, and the front link 39 is rotatably supported by the support base 3 via the front link shaft 35.

  In other words, as shown in FIGS. 8 to 13, the support base portion 3 is positioned forward and upward at a bearing portion 51 that supports the front link shaft 35 and a position adjacent to the axial direction of the bearing portion 51. And an open link arm housing portion 109. The link arm housing portion 109 is formed between a pair of flat surfaces 105 orthogonal to the front link shaft 35. The front link 39 has a shaft hole 113 for holding the front coupling shaft 111 at the upper end portion and a boss portion 115 that is externally mounted on the front link shaft 35 at the base end portion. A link arm 117 is provided. The link arm 117 has a plane corresponding portion 107 corresponding to the link arm accommodating portion 109.

  In the in-use rotation range (U), the plane corresponding portion 107 of the link arm 117 is located between the opposing planes 105 of the link arm accommodating portion 109. Therefore, the left and right front links 39 are prohibited from being detached from the front link shaft 35 and the front connecting shaft 111. On the other hand, in the rotation range at the time of insertion / removal, the plane corresponding portion 107 of the link arm 117 is located outside the plane 105 facing the link arm housing portion 109. Therefore, the left and right front links 39 can be detached from the front link shaft 35 and the front connecting shaft 111. In the assembled state, the front link 39 is set so as not to rotate to the rotation range during insertion / removal. At the time of assembly, the front link 39 is laid back to the front link shaft 111 passed through the front link mounting portion 121 of the seat 5 and the front link shaft 35 passed through the front bearing portion 51 of the main frame 33 from the left and right. Fit. In this state, the front link 39 is tilted forward, and the link arm 117 of the front link 39 is fitted between the opposing flat surfaces 105 of the link arm housing portion 109. Thereafter, the rear link shafts 123 are fitted into the rear link mounting portions 127 located substantially in the middle of the seat receiver 5 and the back support arms 151 are attached from the left and right, whereby the assembly state described above is achieved. That is, the left and right front links 39 can be attached to the main frame 33 without using a retaining part such as a screw.

  The seat base 5 is supported on the support base 3 configured as described above via the front link 39 and the rear link 41.

《Composition of the seat》
As shown in FIGS. 4 to 6, 12, 13, and 15, the seat 5 has a form that can be referred to as an outer shell. In this embodiment, the seat 5 is integrally formed of synthetic resin. A front link mounting portion 121 for mounting the rotating end 119 of the front link 39 via the front connecting shaft 111 at a position from the front end portion of the lower surface of the seat receiver 5 and a substantially central position in the front-rear direction are provided. A rear link attaching portion 127 for attaching the rotating end 125 of the rear link 41 via the rear connecting shaft 123 is provided. The front link mounting portion 121 and the rear link mounting portion 127 are provided integrally with the seat receiver 5.

  Ribs 126 are formed in a grid pattern in the vertical and horizontal directions on the upper surface of the seat 5, and two parallel parts of the ribs 126 extend so as to protrude below the seat 5, and the front link mounting portion 121. And the rear link attaching part 127 is comprised. The left and right sides of the front link mounting portion 121 and the rear link mounting portion 127 are closed by side walls 128 and 130 having through holes. These side walls 128 and 130 may also be formed by extending a part of the rib 126 downward. The other ribs 126 are formed so as to be connected to these ribs 126 at a plurality of locations, and are designed to contribute not only to the strength of the seat 5 itself but also to the strength of the front link mounting portion 121 and the rear link mounting portion 127. ing. That is, the front link mounting portion 121 and the rear link mounting portion 127 are hollow bodies having front walls 118 and 122, rear walls 120 and 124, and left and right side walls 128 and 130, respectively. , 122, the rear walls 120, 124, and the left and right side walls 128, 130 are formed by extending a part of the rib 126 downward.

《Composition of the seat》
As shown in FIGS. 7, 14, and 15, the seat 7 includes an inner shell 129 attached to the upper surface of the seat receiver 5, a cushion 131 disposed on the inner shell 129, and the cushion 131. And a tension fabric 133 stretched on the outer surface.

  As shown in FIG. 15, the inner shell 129 is integrally formed of synthetic resin, and is fixed to the seat receiver 5 with a claw or the like (not shown). The inner shell 129 is provided with a front end drooping portion 135 that gently hangs obliquely downward on the front side, and the intermediate portion 137 bulges below the peripheral portion 139 at the boundary between the intermediate portion 137 and the peripheral portion 139. An annular step 141 is formed.

  As shown in FIGS. 14 and 15, the cushion 131 is made of urethane foam or the like, and includes a cushion hanging portion 143 along the front end hanging portion 135 of the inner shell 129 on the front side. In addition, the upper surface of the cushion 131 which is the core material of the seat 7 is provided with a plurality of uneven portions arranged in one direction, in other words, a plurality of grooves 145 arranged in the front-rear direction in this embodiment.

  As shown in FIGS. 1 to 7, 14, and 15, the upholstery 133 is a bag that covers the cushion 131 and the peripheral edge 139 of the inner shell 129, and the upholstery that is wound around the lower surface of the inner shell 129. The edge 147 of 133 is arranged along the end surface of the step 141 of the inner shell 129. The step 141 and the edge 147 of the upholstery 133 are covered by the seat 5 so as to be hidden. The upholstery 133 has a visual feature portion associated with the groove 145 formed in the cushion 131. In this embodiment, the visual feature portion is a line 149 formed by embossing the stretch fabric 133. In this embodiment, a plurality of the filaments 149 exist so as to be arranged in the front-rear direction, and are present at positions where they overlap with the grooves 145 of the planar cushion 131 from above when the upholstery 133 is placed on the cushion 131. . However, it is important that the line 149 is recognized by the user's vision, and the groove 145 of the cushion 131 and the line 149 of the upholstery 133 do not necessarily overlap in plan view.

<< Configuration of back support body >>
As shown in FIGS. 7 to 9, 16, and 17, the backrest support 9 includes left and right back support arms 151 that extend rearward and upward from the support base 3, and the left and right back support arms 151. The upper connecting member 153 that connects the upper end portions 169 of each of the left and right sides, and the left and right sides that extend integrally from the base end of the torque transmission bracket 57 toward the rear upper side and that contact the inner side surface of the base end portion of the back support arm 151. A back support bracket 155 and a lower connecting member 157 for connecting the rear ends of the left and right back support brackets 155 are provided.

  As shown in FIGS. 1 to 9, 13, and 16 to 18, the left and right back support arms 151 are each made of resin and supported by the support base 3 so as to be rotatable. The front-rear direction extending part 159 and an upright part 161 extending continuously upward from the rear end of the front-rear direction extending part 159 are provided. In the example of illustration, the front-back direction extension part 159 and the standing part 161 have comprised the substantially U shape in the side view. Each back support arm 151 has a shaft mounting for fitting from the outside to the base end portion thereof, that is, the front end portion 163 of the longitudinally extending portion 159, to the end portion 165 of the support shaft 37 provided on the support base portion 3. Part 167 is provided. Each back support arm 151 is provided with an arm protrusion 171 for attaching the upper connecting member 153 to the tip, that is, the upper end 169 of the upright portion 161.

  As shown in FIGS. 3 to 9 and 16, the shaft mounting portion 167 of each back support arm 151 includes a shaft hole 173 that is opened only inward to fit the end portion 165 of the support shaft 37. ing. Specifically, the end 165 of the support shaft 37 is fitted into the shaft hole 173 via a bush 175 so as to be relatively rotatable. The bush 175 is inserted from the inner surface side of the back support bracket 155 before the support shaft 37 is mounted, and the support shaft 37 is fitted into the inner periphery of the bush 175 so as to be relatively rotatable. The flange portion 177 of the bush 175 is located between the back support bracket 155 and the main frame 33. The shaft mounting portion 167 is fitted on the outer periphery of the bush 175, and the end portion 165 of the support shaft 37 is covered by the shaft mounting portion 167. The shaft hole 173 has a tapered shape with a large diameter on the opening end side, and the support shaft 37 has a cylindrical shape. The bush 175 has a shape filling the space between the inner peripheral surface of the shaft hole 173 and the outer peripheral surface of the shaft 37. That is, the outer peripheral surface of the bush 175 has a tapered shape, and the inner peripheral surface has a cylindrical shape having the same cross-sectional shape in each part.

  The rear link 41 is integrally provided on the outer periphery of the shaft mounting portion 167 as shown in FIGS. 3 to 9, 16, and 17. Also, cover members 181 that cover the half 179 of the lower connecting member 157 are integrally projected on the inner side surface of each back support arm 151 in the vicinity of the shaft mounting portion 167. The cover member 181 is provided with a screw insertion hole 183. By screwing a screw 187 inserted into the screw insertion hole 183 into a screw hole 185 provided in the lower connecting member 157, the left and right back holes 183 are inserted. A support arm 151 is attached to the lower connecting member 157.

  In this state, the left and right back support arms 151 are coupled to each other via the lower connecting member 157, so that the shaft mounting portion 167 does not come out of the support shaft 37. That is, the left and right back support brackets 155 whose rear ends are connected by the lower connecting member 157 are supported by the support base 3 via the support shaft 37, and both ends of the support shaft 37 projecting outward from the back support bracket 155. Since the left and right back support arms 151 that rotate together with the back support bracket 155 are supported by the part 165, the left and right back support arms 151 are attached from the left and right outside of the back support bracket 155, so 37, the back support bracket 155 and the lower connecting member 157 can be covered. In this embodiment, the ends 189 of the cover member 181 of the left and right back support arms 151 are closely abutted in the assembled state.

  As shown in FIGS. 7 and 18, the arm projecting portion 171 of the back support arm 151 is for attaching the end of the upper connecting member 153, and is a screw insertion hole 191 and a screw hole continuous to the screw insertion hole 191. And a nut not shown.

  As shown in FIGS. 7 and 18, the upper connecting member 153 is a metal metal having a channel shape, and is installed between the arm projecting portions 171 of the left and right back support arms 151 and screwed to the nut. The screw 195 is attached to each back support arm 151. That is, the upper connecting member 153 has a shape that opens rearward, and is fitted between the upper end portion 169 of the back support arm 151 by being fitted to the arm projecting portion 171 from the front side.

  As shown in FIGS. 9, 12, 13, 16, and 17, the back support bracket 155 is made of metal and is integrally formed with the torque transmission bracket 57. Via the main frame 33 so as to be rotatable.

  As shown in FIGS. 9, 16 and 17, the lower connecting member 157 is made of metal, and both ends thereof are rigidly connected to the rear end of the back support bracket 155 by welding. The lower connecting member 157 has a skeletal function of the back support arm 151 made of synthetic resin in cooperation with the back support bracket 155. Moreover, it also has a function as a base for preventing the back support arm 151 fitted from the left and right from being detached from the left and right. Further, the lower connecting member 157 receives a backward tilting load acting on the backrest 11 via the back support arm 151, and transmits the load via the back support bracket 155 for torque transmission of the tilt reaction force generation mechanism 55. It also has a function of transmitting to the bracket 57.

  The backrest 11 is supported by the backrest support body 9 as described above.

《Composition of backrest》
As shown in FIGS. 1 to 7, the backrest 11 is made of a resin-made back shell 205 that is curved until it becomes substantially horizontal at the top 201 and has an opening 203 for promoting elastic deformation at an almost middle portion thereof. The back shell 205 includes a back support member 209 that supports a leading edge 207 located behind the top portion 201 of the back shell 205, and a tension fabric 206 attached to the surface side of the back shell 205.

  The back shell 205 is made of a resin supported by the backrest support 9 as shown in FIGS. 2 to 7, 19, 20, 22 to 24, and is substantially horizontal at the top 201. And has an opening 203 for promoting elastic deformation substantially in the middle. That is, in the back shell 205, a plurality of belt-like members 213 extending in the vertical direction are arranged in the upper region 211 on the left and right, and the opening 203 is formed between the belt-like members 213. Further, the back shell 205 has a shape corresponding to the waist of the seated person, that is, the waist-corresponding portion 215 having a wide left and right width and gradually becoming narrower as it goes upward in a front view.

  As shown in FIGS. 2 to 7, 19, 20, 22, and 24, the upper region 211 is provided continuously on the front portion 217 that receives the back of the seated person and the upper edge of the front portion 217. The top portion 201 includes an upper curved portion 219 that is curved until it is substantially horizontal, and a back portion 221 that is provided continuously from the rear edge of the upper curved portion 219 and curves downward and hangs down. A groove 223 that opens downward is formed at the leading edge 207 of the back surface portion 221.

  The groove 223 includes a main insertion portion 225 for fitting the back support member 209, and a sub-opening on the back side of the back support member 209 in a state where the back support member 209 is fitted to the main insertion portion 225. And a fitting portion 227. That is, the groove 223 provided in the distal end edge 207 of the back shell 205 is a stepped groove shape in which a main insertion portion 225 and a sub insertion portion 227 are continuously formed, and the main insertion portion 225 has a back support member. When an upper mounting portion 251 (described later) 209 is inserted, only the auxiliary insertion portion 227 is left open and left. The sub insertion portion 227 is continuous with a side edge groove 235 described later, and by attaching the tension fabric 206 using the sub insertion portion 227 and the side edge groove 235, the front shell 205 is moved from the front surface to the upper back surface side. It can be covered with a stretch fabric 206. It should be noted that a rib 228 for adjusting elastic deformation is formed on the belt-like member 213 of the back surface portion 221.

  Further, as shown in FIGS. 2 to 7, 19, 20, and 23, the lower region 229 of the back shell 205 has a concave shape in which the left and right sides protrude forward from the middle in the left-right direction. In the lower region 229, a protrusion 231 continuous with the strip member 213 is formed, and a thin portion 233 continuous with the opening 203 is formed between adjacent protrusions 231. A lower region 229 of the back shell 205 has a portion 215 corresponding to the waist of the seated person raised upward in a side view, and is curved so that the center in plan view is recessed.

  As shown in FIGS. 1, 2, 4, 6, 19, 22, and 23, the back shell 205 has side edge grooves 235 that are opened outward on the left and right side edges, respectively. The side edge grooves 235 and the sub-insertion portions 227 in the grooves 223 are continuous. In addition, a lower edge groove 237 that is continuous with the side edge groove 235 is provided at the lower end of the back shell 205.

  As shown in FIGS. 1 to 6, the lower portion 239 of the back shell 205 is attached to the front surface of the back support arm 151, and the upper portion 243 is supported by the back support member 209. The attachment of the lower part 239 of the back shell 205 will be described. A plurality of nut holes 204 are formed on the front side of the upright portion 161 of the left and right back support arms 151 so as to be spaced apart from each other. On the other hand, screw insertion holes respectively corresponding to the nut holes 204 are provided on the left and right sides of the lower portion 239 of the back shell 205. Accordingly, the mounting screws 241 are inserted through the screw insertion holes from the front and then screwed into the nut holes 204 to tighten the left and right sides of the lower portion 239 of the back shell 205 between the left and right back support arms 151. It can be fixed to the front surface of the upright portion 161. The screw 241 is concealed when the upholstery 206 is provided.

  As shown in FIGS. 1, 2, 4 to 7, 19, 21, 22, 24, and 25, the back support member 209 is a space opened left and right on the back surface of the back shell 205. It is a plate-like one that is arranged facing each other so as to form H.245, and is supported by the backrest support 9 to control the deflection of the back shell 205 in the front-rear direction. The back support member 209 has a concave shape when viewed from the front in which the left and right sides protrude forward from the middle in the left-right direction. The width of the back support member 209 is smaller than the width of the front portion 217 and the lower region 229 of the upper region 211 of the back shell 205. A supporting member main body 247 having a lower mounting portion 249 provided at the lower end of the supporting member main body 247 and attached to the upper connecting member 153; and a main fitting portion 225 of the groove 223 provided at the upper end of the supporting member main body 247. And the rib 253 formed over the upper mounting portion 251, the support member main body 247 and the lower mounting portion 249. Note that the left and right end edges of the back support member are thicker than the middle part, and this functions as a peripheral reinforcing material.

  The support member main body 247 is plate-shaped as shown in FIGS. 4 to 7, 18, 19, 19, 21, 22, 24 and 25, and the left and right sides are more forward than the middle in the left-right direction. A protruding curved shape is formed, and a bent portion 255 is formed below the upper mounting portion 251. The bent portion 255 is shaped such that the upper side of the bent portion 255 is inclined forward with respect to the lower side. In other words, the bent portion 255 is bent in a square shape when viewed from the side.

  As shown in FIGS. 4 to 7, 19, 21, and 24, the upper mounting portion 251 has a thickness dimension that can be closely fitted to the main fitting portion 225, and is in a fitted state. And attached to the back shell 205 using screws 263. That is, the upper attachment portion 251 is a plate-like member extending upward from the upper end of the support member main body 247, and the upper end portion of the rib 253 is located on the front surface thereof. On the front surface of the upper mounting portion 251, the plate nut 257 is disposed between the adjacent ribs 253, and the upper end portion thereof is fitted into the main fitting portion 225 of the groove 223, thereby positioning and holding the plate nut 257. Be able to. The back support member 209 can be attached to the back shell 205 by screwing the screw 263 inserted from the back side through the screw hole 261 of the back shell 205 into the screw hole 259 of the plate nut 257. It has become. In this state, the plate nut 257 is hidden by the back shell 205 and the back support member 209.

  As shown in FIGS. 4 to 7, 19, 21, and 25, the lower mounting portion 249 includes a rear wall 265 that continuously extends downward from the lower end of the support member main body 247, and the rear wall 265. A top wall 267 that extends forward from the upper end of the wall and connects the ribs 253 located in the middle to each other, and a front wall 269 that hangs downward from the front edge of the top wall 267, and the upper connection The material 153 has a shape opened downward so that it can be fitted from above. A screw insertion hole 273 for inserting a screw 271 for attaching the back support member 209 to the upper connecting member 153 is formed in the front wall 269 of the lower attachment portion 249.

  As shown in FIGS. 7, 19, 21, 22, 24, and 25, the rib 253 extends in the vertical direction, and a plurality of ribs 253 are provided on the front surface of the back support member 209. These ribs 253 are shaped so that the projecting dimension gradually decreases toward the upper side. The ribs 253 are arranged on the left and right with a substantially constant interval. The ribs 275 located on both the left and right sides are cut off at the lower end of the support member main body 247 and do not extend to the lower mounting portion 249. The top wall 267 is located below the ribs 275 located on the left and right sides. And the front wall 269 is not provided. On the other hand, the rib 277 located in the middle extends to the front surface of the front wall 269 of the lower mounting portion 249. The protruding dimensions of the ribs 275 located on the left and right sides are set to be smaller than the protruding dimensions of the ribs 277 positioned in the middle. Further, below the back support member 209, the thickness dimension of the ribs 275 located on the left and right sides is larger than the thickness dimension of the ribs 277 located in the middle. Specifically, the ribs 275 located on the left and right sides, which are shorter in the vertical direction than the ribs 277 located in the middle, have a thickness dimension of about 6 millimeters below, while the ribs 277 located in the middle are located below. The thickness dimension is about 4 millimeters. Therefore, when the back support member 209 is viewed from the back side, it seems that there are frames extending in the vertical direction on both the left and right sides.

  As shown in FIGS. 1 to 7 and FIGS. 22 to 24, the tension fabric 206 is mainly composed of a breathable and translucent cloth material, and covers almost the entire area of the back shell 205. The end portion 279 is fixed to the outer peripheral edge of the back shell 205. More specifically, the lower end portion 281 of the upholstery 206 is pushed into the lower edge groove 237 of the back shell 205 and fixed, and the left and right end portions 283 are pushed into the side edge groove 235 of the back shell 205. It is fixed. Further, the upper portion 285 of the upholstery 206 is placed on the outer surface of the upper curved portion 219 and the rear portion 221 of the back shell 205, and the end portion 279 is pushed into the sub-insertion portion 227 of the groove 223 to be fixed. With the tension fabric 206 attached to the back shell 205, the head of the screw 263 that connects the back shell 205 and the back support member 209 is covered.

  The backrest 11 as described above is visible in a state in which both side edges of the back shell 205 protrude outward from both side edges of the back support member 209 in the rear view. In addition, the back side of the upholstery 206 can be visually recognized through the opening 203 of the back shell 205 when viewed obliquely from the rear, and the rib 253 of the back support member 209 can be visually recognized from the perspective viewed from diagonally forward. It is.

  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 to 13, 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.

  Specifically, as shown in FIGS. 4 to 13, the locking mechanism 13 includes a support base portion 3 that holds a front link shaft 35 on the front side and a support shaft 37 on the rear side, and a lower end portion on the front side. The front link 39 supported rotatably on the support base 3 via the link shaft 35 and the lower end portion are integrated with the shaft mounting portion 167 of the back support arm 151 supported by the support shaft 37 so as to rotate. The rear link 41 having the center of movement equal to the center of rotation of the back support arm 151 in side view and the front link mounting portion 121 are connected to the rotation end 119 of the front link 39 via the front connection shaft 111 and the rear. The seat mounting 5 is configured mainly by connecting the link attaching portion 127 to the rotating end 125 of the rear link 41 via the rear connecting shaft 123.

  That is, as shown in FIGS. 4 to 13, the locking mechanism 13 supports the seat base 5 that supports the seat 7 on the support base 3 by the front link 39 and the rear link 41 that are inclined in the same direction. In accordance with the backward tilting operation of the back support arm 151 supported by the support base 3, the front link 39 and the rear link 41 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 portion of the seat 7, that is, the front portion 7a1 of the seat surface 7a more than the rear portion 7a2 of the seat surface 7a when the backrest 11 is tilted backward. is there. 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, unlike a normal locking mechanism, as shown by a two-dot chain line in FIG. 13, the seat 7 is tilted against the load of the seated person while the seat 7 is tilted in accordance with the backward tilting motion of the backrest 11. It is configured to lift.

  Here, in detail with reference to FIG. 13, the dimension γ1 in which the front portion 7a1 of the seating surface 7a, which is the upper surface of the seat 7 provided with the tension fabric 133, is lifted by the backward tilting operation of the backrest 11 is the seating surface. The rear portion 7a2 of 7a is configured to be larger than the lifting dimension γ2.

  More specifically, as shown in FIG. 13, when the backrest 11 is not tilted backward, the forward link 39 has a forward inclination degree larger than the forward inclination degree of the rear link 41. Is set. In other words, the inclination angle α with respect to the horizontal line at the front link 39 is set smaller than the inclination angle β with respect to the horizontal line at the rear link 41 when the backrest 11 is not tilted backward. Further, the center of rotation of the front link 39 relative to the support base 3 is set at a position higher than the center of rotation of the rear link 41 relative to the support base 3. In other words, the axis of the front link shaft 35 is set at a position higher than the axis of the support shaft 37 by a distance h. The effective length dimension of the front link 39, that is, the inter-center distance L1 between the front link shaft 35 and the front connecting shaft 111, and the effective length dimension of the rear link 41, that is, the support shaft that is the rear link shaft. 37 and the rear connecting shaft 123 are set to be substantially the same distance L2. Further, the back support arm 151 is pivotally supported by a portion of the support base 3 that is in front of the leg column 19. In other words, the shaft mounting portion 167 of the back support arm 151 is supported by the support shaft 37 positioned in front of the leg support 19 in a side view.

  The point that the forward tilting degree of the front link 39 is larger than the forward tilting degree of the rear link 41 is intended to lift the front side of the seat 7 relatively larger than the rear side during the rearward tilting. By making the forward tilting degrees of the link 39 and the rear link 41 greatly different from each other, it is possible to set the lift of the front side of the seat 7 when tilting backward to a large value. That is, the front link 39 has many operations for lifting the front portion of the seat 7, that is, the front portion 7a1 of the seating surface 7a, and the rear link 41 is mainly for the operation of moving the seat 7 rearward. As a result, while the seat surface 7a lifts the front portion 7a1 much, the rear portion 7a2 of the seat surface 7a moves backward and moves backward so as to follow the backrest 11 tilting 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 7a relatively rearward.

  The point of making the rotation center positions of the front link 39 and the rear link 41 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 39 and the effective length dimension L2 of the rear link 41 substantially the same, the setting can be made more appropriate. However, of course, the effective length dimension L1 of the front link 39 may be set differently from the effective length dimension L2 of the rear link 41. The arrangement of the front link 39 in the support base 3 and the connection to the seat 5 are also possible. From the setting of the position and the like, for example, the L1 may be set to a dimension slightly longer than L2.

  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 the normal weight-sensing locking mechanism that allows the entire seat to lift upward when tilting is used, a large sense of incongruity, more specifically, against the seated person's expectation, As a result of the entire seat including the seat being lifted up, there is a sense of incongruity caused by the simultaneous movement of the backrest sinking motion and the seat lifting motion opposite to the sinking motion in the vicinity of the seated person's waist. According to the configuration of the 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.

  In the present embodiment, the rear link 41 rotates integrally with the back support arm 151 and the torque transmission bracket 57 around the support shaft 37 that is the rotation center of the back support arm 151. Thereby, not only the interlocking operation of the seat 7 accompanying the back tilting operation of the backrest 11 but also the accurate positioning of the seat 7 by the support base 3 via the rear link 41 is realized. Further, in the present embodiment, the rotation range of the backrest 11 is set to 20 degrees, and the angle formed by the seat surface 7a in the state where the backrest 11 is tilted back as much as possible is compared to when the backrest 11 stands. It is set to tilt 4 degrees backward. That is, in the present embodiment, the backrest 11 by the front link 39 is larger than the dimension γ2 in which the rear portion 7a2 of the seating surface 7a is lifted mainly by lifting the substantially central portion of the seat 5 when the backrest 11 is tilted backward. As a result of setting the dimension γ1 at which the front portion 7a1 of the seat surface 7a is lifted when tilted backward to be larger, the angle of the seat surface 7a when the backrest 11 is fully tilted is tilted by 4 degrees than when the backrest 11 is upright. I have to. In addition, in the present embodiment, since the rear link 41 is connected to the substantially central portion in the front-rear direction of the seat receiver 5, both the front and rear links 39, 41 when the backrest 11 is tilted backward are lifted up. However, since the front link 39 lifts the seat receiver 5 more than the rear link 41, 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. At this time, the height position of the rear end portion of the seat receiver 5 is hardly changed between when the backrest 11 stands and when it tilts backward.

《Arrangement of armrest》
As shown in FIGS. 1 to 7 and 18, the armrest 15 includes an elbow support portion 287 that integrally projects forward from the front surface of the upper end portion of the back support arm 151 of the backrest support 9, and the elbow support portion. And an elbow rest 289 provided on 287.

  As shown in FIGS. 3 to 6 and 18, the elbow support portion 287 has a bottomed boat shape opened upward. One elbow support portion 287, in this embodiment, a bottom wall 291 at the front end portion of the right elbow support portion 287 when viewed from the seated person, is formed with a penetrating window 293, and the lower side through the window 293 The operation lever 295 is protruded. The operation lever 295 is for operating the operation button 31 for unlocking the leg column. The operation lever 295 and the operation button 31 are connected by a wire 297, and the operation force applied to the operation lever 295 is transmitted to the operation button 31 by the wire 297, so that the operation button 31 can be operated. The leg strut can be locked / unlocked. A proximal end portion of the operation lever 295 and one end portion of the wire 297 connected to the operation lever 295 are accommodated in the elbow support portion 287.

  The internal space of the elbow support portion 287 communicates with the wire guide space 298 formed in the standing portion 161 of the back support arm 151. The wire guide space 298 extends in the vertical direction, and a part or all of the wire guide space 298 opens forward. The lower end portion of the wire guide space 298 reaches just above the longitudinally extending portion 159, and is located slightly below the lower end of the back shell 205 in a state where the lower portion 239 of the back shell 205 is attached to the upright portion 161. Open to the front. Therefore, the wire 297 connected to the operation lever 295 is led from the inner space of the elbow support portion 287 to the lower end portion of the wire guide space 298, and then reaches the support base portion 3 along the longitudinally extending portion 159. The

  As shown in FIGS. 1 to 5, 7, and 18, the elbow rest 289 is detachable from the elbow support 287. As a result, any one of a plurality of types of elbow rests 289 that can be attached to the common elbow support 287 can be selected and used. In the elbow rest 289 shown in this embodiment, an attachment base 299 that is directly attached to the elbow support 287 and an elbow rest main body 301 that is supported by the attachment base 299 and on which a seated person's arm is placed are integrated. Is provided.

  The mounting base 299 includes a base 303 that is attached to the upper end 169 of the elbow support 287 and the back support arm 151, and a spacer 305 that extends substantially horizontally from the inner end of the base 303. The base 303 is hooked to the elbow support 287 by a locking mechanism (not shown) on the front side, and the rear side is attached to the front side of the back support arm 151 using screws 305. The spacer 305 of the elbow rest 289 is for filling a space where the top wall 267 directly below the rib 275 does not exist, and has a plate shape substantially continuous with the top wall 267 of the lower mounting portion 249 of the back support member 209. ing. The spacer 305 is closely interposed between the upper surface of the upper connecting member 153 and the lower end surfaces of the ribs 275 located on the left and right sides of the back support member 209.

  As described above, the chair according to the present embodiment has the conventional weight sensing type by tilting the seat 7 relatively backward because the front portion 7a1 of the seat surface 7a is lifted a lot when the backrest 11 is tilted backward. The relative positional relationship with the lower end portion of the backrest 11 is suppressed compared to the above. Thereby, the seated person can effectively suppress the change in posture caused by the back tilt of the backrest 11. Further, with such a configuration, the seat 7 can be provided so that the surface direction toward the backrest 11 in the seating surface 7a always intersects with a certain portion of the lower end portion of the backrest 11 in a side view. As a result, the virtual portion of the backrest 11 located on the rearward extension line of the seating surface 7a when the backrest 11 stands and tilts backward can be suppressed from being displaced in the vertical direction. In addition, even in the case of this embodiment, even if it is a weight sensing type, as in the conventional case, the two adjacent locations of the lower end of the backrest and the rear end of the seat are in opposite directions for the human skeleton. The rear end portion of the seat 7 is tilted backward so that the relative positional relationship with the lower end portion of the backrest 11 is not changed as much as possible. A configuration is adopted in which the front part, that is, the front part 7a1 of the seating surface 7a is relatively raised from the intermediate part. As a result, when the backrest 11 tilts backward, a portion that rises with the weight of the seated person is created, and the center of gravity of the upper body due to the backrest 11 tilting backward is lowered. It is linked to the rise of As a result, it is possible to compensate for the difference in the backward tilting force necessary for the backrest 11 due to the difference in the weight of the seated person using the weight of the seated person without a sense of incongruity. That is, the chair according to the present embodiment can smoothly continue the desk work comfortably without causing a sense of incongruity even if the work at the time of standing back and tilting back is frequently switched.

  In the present embodiment, as a configuration for largely lifting the front portion 7a1 of the seat surface 7a in the seat 7, first, when the backrest 11 is not tilted backward, the forward link 39 has a forward inclination degree of the rear link 41. By setting the degree of forward inclination to be greater than the forward link 39, the direction of the tangent of the locus drawn by the rotational movement of the front link 39 is made closer to the vertical direction, so that the front and rear links 39, 41 are rotated by the same angle. Also, the front link 39 can be moved up more greatly.

  In addition, in the present embodiment, the degree of forward tilt of the front and rear links 39, 41 is set as a mode in which the center of rotation of the front link 39 with respect to the support base 3 is set higher than the center of rotation of the rear link 41 with respect to the support base 3. Even if they are different, they are connected to the front and rear link attaching portions 121 and 127 at substantially the same height on the lower surface side of the seat 5. That is, the seat receiver 5 effectively avoids securing the vertical dimension for attaching the front and rear links, and contributes to reducing the thickness dimension of the seat receiver 5.

  In particular, in the present embodiment, the back support arm 151 is pivotally supported on a portion of the support base 3 that is in front of the leg column 19, so that the turning radius due to the backward tilting action of the backrest 11 is increased, and the seated person As a result of raising the front part 7a1 of the seating surface 7a more than the rear part 7a2 as described above, the relative position between the rear end part of the seat 7 and the lower end part of the backrest 11 is increased. Change in the general positional relationship or the direction of the seat 7 is minimized, and a sense of incongruity is unlikely to occur.

  Further, when the back support arm 151 is pivotally supported on the front portion of the support base 3 with respect to the leg column 19 as in the present embodiment, the backrest 11 is lowered due to the backward tilt of the backrest 11. The load of the seated person on the backrest 11 increases, and the load difference due to the difference in the weight of the seated person increases. Therefore, in the case of a chair having a synchro-rocking mechanism that combines the backward tilting of the backrest 1 and the lowering of the seat 7 as in the prior art, a large tilting reaction force generation mechanism that can handle a wide range of loads is required for the support base. In addition, a tilt reaction force adjustment mechanism is also required separately. However, the chair according to the present embodiment employs a weight sensing type as described above. That is, as the load applied to the backrest 11 of the seated person increases in proportion to the body weight, the force required to raise the seat 7 against the body weight of the seated person increases, so that they can preferably cancel each other. It has become a thing. As a result, even the above-described tilt reaction force generation mechanism 55 without a tilt reaction force adjustment mechanism can provide a comfortable tilt reaction force regardless of the weight of the seated person.

  On the other hand, in this embodiment, since the rear link 41 is integrally formed with the back support arm 151 that supports the backrest 11, the components for causing the backrest 11 and the seat 7 to operate can be effectively reduced. It has become.

  And while supporting the seat 7 suitably using the tilting reaction force of the backrest 11, the number of parts for supporting the backrest 11 and the seat 7 is effectively reduced, and further, the tilting reaction force generating mechanism 55 is provided. In the present embodiment, as a configuration for realizing simple and compact, the back end of the back support arm 151 protrudes from the rearward inclined shaft portion of the front-facing front end portion to the front downward direction. A torque transmission bracket 57 is provided as a torque transmission member that compresses the spring 63 when tilted backward, and the back support arm 151, the rear link 41, and the torque transmission bracket 57 operate integrally.

  In particular, in this embodiment, the rear link 41 of the seat 7 is used in the present embodiment in order to accurately sense the weight of the seated person by the seated person 7 and to lift the seat 7 reliably by the action of the backrest 11. Space for operating the seat 7 near the rear end of the seat 7 is effective by supporting the substantially center in the front-rear direction and avoiding the rear link 41 located near the rear end of the seat 7. To ensure.

  The present invention is not limited to the embodiment described in detail above. In the above-described embodiment, the front link lifts the seat receiver more than the rear link, so that the rear end portion of the seat receiver is relatively lowered from the front end portion. Although the height position of the rear end portion is almost the same between when the backrest is raised and when it is tilted backward, it is of course possible to set the rear end portion of the seat so as to be lowered.

  For example, in the above embodiment, the effective length dimension of the front link and the effective length dimension of the rear link are set to substantially equal dimensions, but the effective length dimension of the front link is set to the effective length dimension of the rear link. It may be set larger. Even if such a configuration is applied, a chair that lifts the front part of the seat more than the rear part of the seat can be realized.

  Further, the effective length dimension of the front link can be obtained without applying the aspect in which the rotation center of the front link with respect to the support base is set to a position higher than the rotation center of the rear link with respect to the support base as in the above embodiment. Is set to be larger than the effective length dimension of the rear link, and the forward link is tilted forward more than the forward link when the backrest is not tilted backward. It is possible to implement | achieve the structure which lifts the front part of a seat more than the rear part of a seat combining with the structure to perform.

  Further, the configuration is such that the effective length dimension of the front link is set to be larger than the effective length dimension of the rear link, and the rotational center of the front link relative to the support base is higher than the rotational center of the rear link relative to the support base. A configuration in which the front portion of the seat is lifted more than the rear portion of the seat may be realized in combination with the configuration set in (1).

  Moreover, although the aspect which comprises a back support arm and a back link integrally was disclosed in the said embodiment, of course, even if it is an aspect which comprises a back support arm and a front link integrally, the front part of a seat is seated. It is possible to realize a configuration that lifts more than the rear part.

  Furthermore, in the above embodiment, the back tilt angle of the seat surface when the backrest is tilted back by 20 degrees is set to 4 degrees. The tilt angle is not limited to the above 4 degrees, and an appropriate setting can be applied.

  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.

  INDUSTRIAL APPLICABILITY The present invention can be used as a chair having a synchro-rocking mechanism in which a backrest and a seat used in an office operate in conjunction with each other.

DESCRIPTION OF SYMBOLS 3 ... Support base 5 ... Seat receiver 7 ... Seat 19 ... Leg support 39 ... Front link 41 ... Rear link 57 ... Torque transmission member (torque transmission bracket)
63 ... Elastic member (spring)
151 ... Back support arm

Claims (7)

The seat support that supports the seat is supported directly or indirectly on the support base by the front link and the rear link that are inclined in the same direction, and the front support is supported by the backward tilting motion of the back support arm supported by the support base. A chair having a weight sensing type locking mechanism configured to rotate the link and the rear link in an upright direction to lift the seat support upward, and the front portion of the seat is seated when the backrest is tilted backward Configured to lift more than the rear,
The rear link is integrally formed with the back support arm so that the connecting shaft of the rear link and the seat support is positioned forward of the center of rotation of the rear link with respect to the support base , and the front link is A chair that is configured separately from the support arm. 2. The chair according to claim 1, wherein when the backrest is not tilted backward, the front link is set to have a forward inclination degree larger than a forward inclination degree of the rear link. The chair according to claim 1 or 2, wherein an effective length dimension of the front link is set larger than an effective length dimension of the rear link. The chair according to claim 2 or 3, wherein a rotation center of the front link with respect to the support base is set at a position higher than a rotation center of the rear link with respect to the support base. The chair according to claim 1, 2, 3, or 4, wherein the back support arm is pivotally supported at a position in front of the leg column in the support base. A torque transmitting member that is provided so as to protrude downward in the forward direction from the rearward tilting shaft portion of the forward-facing front end portion of the back support arm, and that compresses the elastic member when the back is tilted at the projected tip portion;
The chair according to claim 1, 2, 3 or 5, wherein the back support arm, the rear link and the torque transmission member operate integrally. The chair according to claim 1, 2, 3, 4, 5 or 6, wherein the rear link supports a substantially center in the front-rear direction of the seat.

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