Chair backrest

Abstract

To improve operability and the like in providing a backrest equipped with a back shell body with a lumbar support device.SOLUTION: A backrest 3 includes a shell body 6, a back cushion 7 arranged in front of the same, and a skin material 13 covering the same. The back cushion 7 is supported by a support pad 14 from the back. The support pad 14 is lifted / lowered by a lifting / lowering body 20 that has an inclination part 49 which has a rear downward and a lifting / lowering operation part 17 having at a rear end part a knob 15 received in the back. To the shell body 6, a sleeve body 16 guiding the lifting / lowering body 20 is fitted. The knob 15 is positioned at the height of a lower part of the support pad 14, so that the arm does not have to be bent unnaturally when operating and the support pad 14 can be lifted / lowered lightly.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a chair back with a lumbar support device. [Background technology]

[0002] It is common to provide a lumbar support device on the back of a chair, which supports the user's lower back from behind with a support pad. There are two types of lumbar support devices: a fixed type in which the height of the support pad is fixed, and a lifting type in which the height of the support pad can be adjusted. However, the lifting type lumbar support device has an operating member, so how to position the operating member becomes an issue.

[0003] The structure and arrangement of the operating members are closely related to the structure of the backrest. For example, Patent Document 1 discloses that in a backrest type in which the back panel is exposed at the rear, vertical longitudinal slits are formed on both the left and right sides of the back panel, and an operating knob is exposed from this slit.

[0004] On the other hand, Patent Document 2 discloses that in a backrest whose back surface is formed from a back shell body, a longitudinal slit is formed in the middle of the top and bottom of the back shell body, and an operating lever is exposed to the rear from this slit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2002-191462 A [Patent Document 2] JP 2019-103675 A Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, the support pad is long in the left-right direction, and therefore, operating knobs are provided on the left and right ends of the support pad and are connected to the support pad via slits. However, because the knobs are located on both the left and right sides of the backrest, in order to operate the chair while seated, the user must reach behind them and spread both hands out on both sides to place their hands on the knobs. This tends to cause the arms to bend unnaturally, which raises concerns about poor operability.

[0007] In addition, the knob is positioned higher than the support pad. I Because the knob must be raised to a fairly high height, it is difficult to operate while seated, which also raises concerns about poor operability.

[0008] On the other hand, in Patent Document 2, the operating member extends downward from the slit, so that it is possible to raise and lower the chair without having to spread one's arms while seated, and therefore it can be said to be easy to operate and user-friendly.

[0009] The present invention was made against this background, and aims to provide an improved form for a backrest equipped with a back shell body, such as smoother lifting and lowering movement of the support pad and improved operability. [Means for solving the problem]

[0010] The backrest of the present invention is "The seatback is provided with a back shell body that constitutes the back of the backrest, a back cushion that is disposed in front of the back shell body, and a lumbar support device that supports the seated person from behind via the back cushion. The lumbar support device has a support pad arranged between the back cushion and the back shell body so as to be movable up and down, and a lifting operation unit for adjusting the height of the support pad from behind the back shell body. This is the basic configuration.

[0011] In the invention of claim 1, in the above basic configuration, "A vertically elongated long hole through which a part of the lifting operation unit passes freely in the back shell body. and a plurality of guide parts for guiding the up and down movement of the lifting operation part at least at two points, a front and a rear, are formed, and at least one of the plurality of guide parts is provided with a locking means for holding the height of the support pad and the lifting operation part in a stepped or stepless manner, Furthermore, the lifting operation unit has a lifting body that is guided in the long hole so as not to fall in the front-rear direction, and a knob that is provided on the lifting body and positioned outside the back shell body. " The structure is as follows.

[0012] As the support pad rises and falls, the relative height between the support pad and the elongated hole changes, but the elongated hole only needs to overlap or protrude below the lifting area of ​​the support pad in rear view.

[0014] Claim 1 of As an example of the development, claims 2 So, first, "The back shell body includes a vertically long sleeve body in which the long hole is formed, and a shell main body to which the sleeve body is attached, and the shell main body has vertically long mounting holes into which the sleeve body is fitted." The structure is as follows.

[0015] Furthermore, claim 2 states: "The above Lifting body has an insertion portion disposed inside the sleeve body so as to be movable up and down, and a guide portion located in front of the insertion portion and engaging with the shell body directly or via a guide body so as to be immovable forward and backward and to be movable up and down, The guide portion has a protruding portion that protrudes to the left and right beyond the insertion portion, and the protruding portion engages with a groove formed between a rearward opening edge provided in the shell body and the rear edge of the sleeve body. The structure is as follows.

[0016] Furthermore, claims of 2 As an example of the development, claims 3 So, "The rear surface of the shell body is covered with a skin material, an opening through which the sleeve body passes is formed in the skin material, and the edge of the skin material surrounding the opening is covered from behind by the sleeve body." The structure is as follows. Effect of the Invention

[0019] Since the support pad supports the lower back of a seated person, if the support pad is at the height of the lifting area, the seated person can operate the operating member with their hands behind their back without any particular strain. In claim 1 of the present application, the long hole is formed at a height that overlaps with the lifting area of ​​the support pad or partially extends below it, so that the lifting and lowering operation of the operating member can be easily performed without bending the arms unnaturally.

[0020] When the support pad is in the lowest position and the long hole protrudes below the support pad, the exposed portion (finger hook) of the lift operation part is located below the support pad, so that the lift operation can be performed with the arms behind the back and with little bending. Therefore, this is particularly preferable.

[0021] Regarding the lifting operation unit, the knob on which the user places his / her finger can be of various shapes. 1 By adopting a shape that protrudes on both the left and right sides of the long hole as shown in FIG. 1, the knob can be firmly grasped and forcefully moved up and down, further improving operability. Lifting body It is also possible to prevent the portion (insertion portion) that is fitted into the elongated hole from coming out forward by using a knob, which makes it possible to simplify the structure of the lifting operation portion.

[0022] It is possible to form the elongated hole directly in the back shell as a one-part structure, but 2 As described above, by forming the back shell body with the shell main body and the sleeve body and forming a long hole in the sleeve body, it is possible to make the sleeve body out of a material different from that of the shell main body, making it easier to raise and lower the lifting and lowering operation part, and to make it easier to attach and guide the lifting and lowering operation part while facilitating the molding of the shell main body. Therefore, it is practical.

[0023] Claim 2 When the configuration of Lifting body The protruding parts (guide parts, flanges) of the lifting operation part are surrounded by the shell body and the sleeve body. (Lifting body)The lifting operation unit can be raised and lowered smoothly by suppressing the inclination of the lifting operation unit in the front-rear direction, and the sleeve member that is fitted into the shell body from the rear also serves as the guide means, making it easy to mold the shell body. Therefore, the lifting operation unit can be raised and lowered smoothly without compromising the ease of molding the shell body.

[0024] In chairs equipped with a back shell body, the back of the chair is also covered with a skin material. In other words, the entire backrest is covered with the skin material. This configuration makes it possible to give the backrest a high fashionability. 3 The invention of the above is applied to a stuffed type, but since the covering material can be pressed and held by the sleeve body, the covering material can be kept in a tight state.

[0025] In addition, if the knob of the lifting operation part hits the surface material, it becomes difficult to move and the surface material is easily worn out. 3 In the invention, the knob of the lifting / lowering operation part does not come into contact with the covering material, so that deterioration of the smoothness of the lifting / lowering movement and wear on the covering material can be prevented.

[0026] Now, if there is a gap between the support pad and the back shell body, the length of the lifting / lowering operation part becomes longer, which makes it easier for the lifting / lowering operation part and the support pad to become distorted when being raised or lowered. That is, the lifting / lowering operation part is raised or lowered by hooking a finger on its rear end, so the back shell body has a tendency to rotate in the front-to-rear direction when being raised or lowered, and the longer the length, the easier it becomes to rotate and the more likely it is to become distorted.

[0027] In this respect, 1 By adopting this configuration, the lifting operation part is guided at multiple points in the front and rear, so that even if the gap between the support pad and the knob is large, the lifting operation part can be prevented from falling over and the support pad can be lifted and lowered smoothly. In addition, the support pad can be held at a desired height by the locking means, but since the locking means is provided on one of the guide parts, the structure can be simplified accordingly. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 shows an embodiment, in which (A) is a perspective view seen from the front with the skin material omitted, (B) is a perspective view seen from the back, and (C) is a side view. [Diagram 2] 1A is a perspective view of the back cushion separated, FIG. 1B is a perspective view of the lower cover separated from the rear, and FIG. 1C is a perspective view of the auxiliary cover separated. [Diagram 3] FIG. 2A is a perspective view of a lumbar support device, and FIG. [Figure 4] 1A is an exploded perspective view of the entire lumbar support device as viewed from the front, FIG. 1B is a perspective view of the lifting / lowering operation unit as viewed from the front, and FIG. [Diagram 5] (A) is an exploded perspective view of the entire lumbar support device seen from behind, (B) is an exploded perspective view showing the relationship between the lifting / lowering operation unit and the support pad, and (C) is an exploded perspective view of the support pad attached to the lifting / lowering operation unit. [Figure 6] FIG. 2 is a separated perspective view of the lifting body and the shell main body. [Figure 7] FIG. [Figure 8] 1A is a plan cross-sectional view taken at the middle part of the knob from above and below, and FIG. 1B is an exploded perspective view showing the lifting / lowering operation part. [Figure 9] FIG. 9 is a cross-sectional plan view taken along line IX-IX of FIG. 7. [Figure 10] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] (1) Overview of the embodiment Next, an embodiment of the present invention will be described with reference to the drawings. The chair of this embodiment is a swivel chair that is widely used for office work, and as shown in Fig. 1, it comprises a leg device 1, a seat 2, and a backrest 3 as basic elements. A base 4 is attached to the upper end of the leg support that constitutes the leg device 1, and the backrest 3 is attached to a tilting frame 5 that is connected to the base 4 so as to be able to tilt freely backward.

[0030] As shown in FIG. 1(B), the backrest 3 comprises a shell body 6, which is a molded product made of synthetic resin, and a back cushion 7 arranged on its front side. On the lower rear surface of the shell body 6, an upwardly curved crescent-shaped lower bracket 8 and a back cover 9 positioned on top of it are arranged. Furthermore, side covers 10 are attached to the rear surfaces of both the left and right ends of the lower bracket 8.

[0031] 2(C), the shell body 6 is formed in the shape of a shallow tray that opens forward, with numerous reinforcing ribs formed inside, and the back cushion 7 is disposed in front of the group of reinforcing ribs, with spacer plates 11, 12 interposed between the upper half and lower end. The back cushion 7 is covered with a skin material 13, which is formed in a bag shape and also covers the back surface of the shell body 6, leaving the lower bracket 8 and back cover 9 exposed.

[0032] A support pad 14 constituting the lumbar support device is disposed between the back cushion 7 and the shell body 6, and a knob (lever) 15 constituting a lifting / lowering operation part of the lumbar support device is disposed behind the shell body 6. On the other hand, a vertically elongated sleeve body 16 constituting a part of the back shell body is attached to the shell body 6, and a vertically elongated long hole 17 is formed in the sleeve body 16, and the knob 15 is guided by the sleeve body 16 so as to be freely movable up and down. Therefore, the shell body 6 and the sleeve body 16 constitute the back shell body.

[0033] (2) Lumbar support device Next, the lumbar support device will be described. As shown in Fig. 3 to 5, the lumbar support device includes the support pad 14 and the lifting / lowering operation unit 19 for moving the support pad 14 up and down. The lifting / lowering operation unit 19 includes a lifting body 20 having the support pad 14 attached to the upper front end and the knob 15 attached to the lower rear end, a slider 22 fixed to the upper front end of the lifting body 20 with a screw 21, a guide body 23 to which the slider 22 is attached so as to be movable up and down, and a catch 24 disposed inside the guide body 23 and engaged with the slider 22.

[0034] For example, as shown in Fig. 3, the support pad 14 is formed in a horizontally elongated egg shape, and is curved so as to bulge forward when viewed from the side and in a plan view. For example, as shown in Figs. 3(A) and (B), the rear surface of the support pad 14 is formed with rearward-facing guide protrusions 25 at four locations on the top, bottom, left and right. There are On the other hand, a guide frame 26 is formed on the front surface of the shell body 6, into which the guide protrusion 25 is fitted so as to be immovable in the left-right direction but movable up-down.

[0035] A guide groove 27 that is open above, below and to the rear is cut out and formed at the tip of the guide protrusion 25, while a guide rib 28 into which the guide groove 27 of the guide protrusion 25 fits freely is formed inside the guide frame 26, as shown in Figure 6, for example.

[0036] As shown in Figures 4(A) and 5(A), a square head portion 29 is formed at the upper front end of the lifting body 20, and a square boss portion 30 is protruded forward from the center of the head portion 29, while a square recess 30a into which the boss portion 30 fits is formed on the rear surface of the slider 22. The slider 22 is fixed to the head portion 29 with screws 21 with the boss portion 30 and the square recess 30a fitted together.

[0037] 4(A) and 5(A), the slider 22 is formed in a rectangular shape elongated from side to side, and has positioning protrusions 31 formed on both the left and right sides, while the catch 24 has a pair of engaging claws 32 in a generally V-shaped configuration, and the bases of the engaging claws 32 are embraced from the left and right by the positioning protrusions 31 of the slider 22. Furthermore, a rectangular protrusion 33 formed on the front surface of the slider 22 is fitted into a rectangular recess 30a formed in the catch 24.

[0038] Therefore, the engagement between the rectangular protrusion 33 and the rectangular recess 30a prevents the catch 24 from moving left or right or downward, and the left and right positioning protrusions 31 clamp the upper part of the catch 24 from the left and right, preventing the catch 24 from moving upward.

[0039] Furthermore, as shown in Figure 5 (B), for example, a hanging protrusion 34 having an upward hook-shaped tip is formed on the rear surface of a portion of the support pad 14 near the upper end, while a hanging frame 35 is formed on the upper front end of the catch 24, into which the hanging protrusion 34 of the support pad 14 fits from the front, and the fitting of these hanging protrusions 34 and hanging frame 35 allows the support pad 14 to rise and fall together with the lifting body 20.

[0040] For example, as shown in Figures 4(A) and 5(A), the guide body 23 is formed in a rectangular shape when viewed from the front, and a guide recess 36 is formed inside into which the slider 22 fits so as to be movable up and down. As shown in Figure 4(A), a front rib 38 and a rear rib 39 are formed on both the left and right sides of the guide recess 36, and the slider 22 is held between these front and rear ribs 38, 39 so as to be movable up and down. Also, as shown by the arrow X in Figure 4(A), the slider 22 and the catch 24 are fitted into the guide body 23 from above.

[0041] As shown in Fig. 4(A), downward hook-shaped claws 40 are formed on the left and right sides at the lower end of guide body 23, while upward ribs 41 onto which hook-shaped claws 40 hook from above are formed on shell body 6 as shown in Fig. 6, thereby preventing the lower end of guide body 23 from moving forward, while a flange 42 provided at the upper end is fixed to a fixing part 44 (see Fig. 8(B)) of shell body 6 with a screw 43. As shown in Fig. 7, a nut 45 (see also Fig. 3(A)) is arranged behind fixing part 44.

[0042] For example, as shown in Fig. 4(A)(C), a rack is formed by providing multiple engagement protrusions 48 for height adjustment on the left and right inner surfaces of the guide body 23, and the support pad 14 is held at a desired height by fitting the engagement claws 32 of the catch 24 into the recesses between the engagement protrusions 48 adjacent to each other vertically. The height can be adjusted by elastically deforming the engagement claws 32. As shown in Fig. 7, a resin sheet backing plate 46 can be interposed between the back cushion 7 and the support pad 14. As shown in Fig. 3(A), the support pad 14 is provided with ribs 14a that are shaped like a mountain when viewed from the side and located on both the left and right sides of the guide body 23.

[0043] As shown in Figures 4(A) and 5, the lifting body 20 has an inclined portion 49 extending downward from the head portion 29, and a boss body 50 with a square cross section protruding rearward from the lower end of the inclined portion 49. Meanwhile, the sleeve body 16 has a vertically elongated tubular portion 51 into which the boss body 50 is slidably fitted, and a flange 52 protruding outward from the rear end of the tubular portion 51, and as shown in Figure 8(A), the tubular portion 51 is fitted into an opening 53 formed in the shell main body 6. The edge of the skin material 13 is pressed and held by the flange 52.

[0044] 7, the shell body 6 is curved so that the part of the shell body 6 that contacts the lower back of a seated person is located at the frontmost position, and is curved so that the shell body 6 is concave in a frontward direction when viewed from the side. The support pad 14 is disposed at the part that protrudes forward in a side view, and the sleeve body 16 is also disposed at the curved part of the shell body 6.

[0045] The front surface of the cylindrical portion 51 and the rear surface of the flange 52 are straight and parallel to each other in a side view. The flange 52 is formed so that its thickness increases from front to rear toward the top, so that the sleeve body 16 can be gently tilted backward. setting is doing.

[0046] For example, as shown in Fig. 4, the shell body 6 is formed with a forward opening groove 54 into which the inclined portion 49 of the lifting body 20 is loosely fitted so as to be able to move up and down. On the other hand, as shown in Figs. 4(A) and 7, for example, engagement holes 55 are formed on both the left and right sides and the upper end of the tubular portion 51 of the sleeve body 16, and as shown in Fig. 8(A), engagement claws 56 (see also Fig. 6) formed on the widened portion 54a of the forward opening groove 54 are fitted into the engagement holes 55, thereby lifting the sleeve body 16 backward. move It is impossible to hold.

[0047] The boss body 50 of the lifting body 20 has a protruding portion 50a exposed behind the sleeve body 16, and the knob 15 is fitted into the protruding portion 50a from behind and fixed with a screw 57 inserted / screwed in from below.

[0048] For example, as shown in FIG. 4, a flange-shaped protrusion 58 protruding to the left and right is provided as a guide portion at the lower end of the inclined portion 49 of the lifting body 20, and the rear surface of the protrusion 58 abuts or is in close contact with the front surface of the tubular portion 51 of the sleeve body 16, while as can be seen from FIGS. 6 and 7, the left and right side surfaces of the protrusion 58 abut or are in close contact with the left and right inner surfaces of the forward-facing opening groove 54.

[0049] In this case, as shown in Figs. 6 and 7, a forward step 54b is formed in a portion of the forward opening groove 54 below the widened portion 54a, while a rearward step 54c is formed as shown in Figs. 6, 7 and 9. The protruding portion 58 of the lifting body 20 is sandwiched between the front surface of the sleeve body 16 and the rearward step 54c, thereby guiding the up and down movement of the lifting body 20 (the lifting body 20 is To Guide to prevent falling Being raised and lowered That is, the protruding portion 58 of the lifting body 20 is inserted into the groove formed by the sleeve body 16 and the rearward step portion 54c. As a result, the lift body 20 is guided so as to move up and down without tipping over in the forward and backward directions.

[0050] 6 and 7, the vertical length (height) of the overhanging portion 58 is slightly smaller than the combined vertical length of the widened portion 54a and the vertical length of the forward step portion 54b in the forward opening groove 54. Therefore, when the overhanging portion 58 is inserted into the forward opening groove 54 with the lifting body 20 positioned at the lowest end without the sleeve body 16 attached, and the overhanging portion 58 is raised after it hits the forward step portion 54b, the overhanging portion 58 is positioned behind the rear step portion 54c. Therefore, when the sleeve body 16 is attached in this state, the lifting body 20 cannot descend to the lowest stage, and the overhanging portion 58 is held sandwiched between the sleeve body 16 and the rear step portion 54c from the front and rear.

[0051] (3) Summary In the above configuration, as shown in Fig. 7, when the support pad 14 is in the lowest position, the sleeve body 16 is located at a position overlapping the support pad 14 in a rear view, and therefore the knob 15 is located at the same height as the lower end of the support pad 14. Therefore, when a seated person operates the knob 15 with their back hand to raise or lower the support pad 14, the person can operate the knob 15 in a natural position with almost no bending of the arm. Therefore, the support pad 14 can be raised or lowered by smoothly moving the knob 15 up and down.

[0052] Since the support pad 14 and the knob 15 are spaced apart in the front-rear and up-down directions, if there is only one guide, the lifting body 20 will tend to tip over in the front-rear direction when the knob 15 moves up and down. do However, in this embodiment, the lifting body 20 can be raised and lowered smoothly without any kinking because the protruding portion 58 at the lower end of the inclined portion 49 and the head portion 29 at the lower end are held so as to be unable to move back and forth but can move up and down.

[0053] It is also possible to insert the boss body 50 of the lifting body 20 from the front into the long hole formed in the shell main body 6 without using the sleeve body 16, but using the sleeve body 16 and forming the long hole 17 in the sleeve body 16 as in this embodiment has the advantage that the lifting body 20 can rise and fall more smoothly by forming the sleeve body 16 from a material with a low friction coefficient, and the skin material 13 can be held down by the sleeve body 16.

[0054] As described above, the protruding portion 58 of the lifting body 20 fits into a groove formed by the rearward step portion 54c of the shell main body 6 and the sleeve body 16, preventing the lifting body 20 from tipping forward or backward (eliminating twisting) and allowing for smooth lifting and lowering operations.

[0055] For example, as shown in Fig. 4(A), the lower end of the guide frame 23 is formed of a lower frame 23a. As described above, the slider 22 of the lifting body 20 is inserted into the guide frame 23 from above, and as shown in Fig. 7, the slider 22 hits the lower frame 23a of the guide frame 23, thereby defining the lower limit of the slider 22.

[0056] The slider 22 hits the lower frame 23a of the guide frame 23 to determine the lower limit height of the lifting body 20, but in this state, as shown in Figure 7, the boss body 50 of the lifting body 20 is located slightly above the lower end of the sleeve body 16, and the protruding portion 58 of the lifting body 20 is engaged with the rearward facing step portion 54c of the forward opening 54. Therefore, the boss body 50 is held so that it cannot slip out forward.

[0057] The lumbar support device can be assembled, for example, in the following procedure. That is, the catch 24 is attached to the slider 22 and set in the guide frame 23, while the sleeve body 16 is removed and the protruding portion 58 of the lifting body 20 is inserted from the front into the lower end of the forward opening groove and raised, the slider 22 is fixed to the head 29 of the lifting body 20 with a pin 21, the knob 15 is fixed to the protruding portion 50a of the boss body 50 of the lifting body 20 with a screw 57, the support pad 14 is engaged with the suspension frame 35 of the catch 24, and the guide protrusion 25 of the support pad 14 is fitted into the guide frame 26 of the shell body 6. Either the knob 15 or the support pad 14 may be attached first.

[0058] When the guide protrusions 25 are provided on the support pad 14 as in this embodiment, the support pad 14 is prevented from falling forward or backward, and the support pad 14 can be raised and lowered smoothly. In particular, when the upper part is attached to the lifting body 20, the upward movement may be smooth, but the downward movement may be easily strained. However, when the guide protrusions 25 are provided, the support pad 14 can be raised and lowered smoothly regardless of the mounting height position with respect to the lifting body 20.

[0059] In the above embodiment, the elongated hole 17 of the sleeve body 16 is exposed, but as shown in Fig. 10 as another embodiment, it is also possible to form a vertically elongated cover portion 15a in the knob 15 that covers the elongated hole 17. In this way, as the knob 15 moves up and down, the cover portion 15a also moves up and down, so that the elongated hole 17 can be kept always covered, and it is possible to prevent fingers or foreign objects from being pinched, or to prevent dust and dirt from entering.

[0060] Although the embodiment of the present invention has been described above, the present invention can be embodied in various other ways. For example, the support pad is not limited to a horizontally elongated oval shape as shown in the figure, and various shapes such as a square or a circle can be adopted. Also, the lifting operation unit does not necessarily need to be provided with an inclined portion. The height adjustment means is not limited to a stepwise height adjustment using an engagement claw as in the embodiment, but a stepless height adjustment mechanism using a damper or the like can also be adopted. [Industrial Applicability]

[0061] The present invention can be embodied in a backrest equipped with a lumbar support device, and therefore has industrial applicability. [Explanation of symbols]

[0062] 3. Backrest 6 Shell body 7 Back cushion 13 Skin material 15 Picking 16 Sleeve body 17 Slot 19 Lifting operation unit 20 Lifting body 22 Slider 23 Guide body constituting the guide section 24 Catch Body 29 Head 32 Engagement claw 48 Engagement protrusion 49 Slope 50 Boss Body 51 Cylinder part 52 Flange 53 Shell body opening 54 Forward opening groove 54a Widened portion of forward opening groove 54b Forward step 54c Backward step 58 Overhang

Claims

1. The seatback includes a back shell body that constitutes a back portion of the backrest, a back cushion disposed in front of the back shell body, and a lumbar support device that supports a seated person from behind via the back cushion. The lumbar support device has a support pad arranged between the back cushion and the back shell body so as to be movable up and down, and a lifting operation unit that adjusts the height of the support pad from behind the back shell body, The back shell body is formed with a vertically long hole through which a part of the lifting operation unit passes so as to be movable up and down, and a plurality of guide parts that guide the vertical movement of the lifting operation unit at least at two points, the front and the rear, and at least one of the plurality of guide parts is provided with a locking means that holds the height of the support pad and the lifting operation unit in a stepped or stepless manner, Furthermore, the lifting operation unit has a lifting body that is guided so as not to fall in the forward and backward directions in the long hole, and a knob that is provided on the lifting body and positioned outside the back shell body. Chair backrest.

2. The back shell body comprises a vertically elongated sleeve body in which the long hole is formed, and a shell body to which the sleeve body is attached, and the shell body has vertically elongated mounting holes into which the sleeve body is fitted, the lifting body has an insertion part disposed inside the sleeve body so as to be movable up and down, and a guide part located in front of the insertion part and engaging with the shell main body directly or via a guide body so as to be immovable forward and backward and to be liftable, The guide portion has a protruding portion that protrudes laterally beyond the insertion portion, and the protruding portion is engaged with a groove formed between a rearward opening edge of the shell main body and a rear edge of the sleeve body. A chair back according to claim 1.

3. The back surface of the shell body is covered with a skin material, the skin material has an opening through which the sleeve body penetrates, and the edge of the skin material surrounding the opening is covered from behind by the sleeve body. A chair back according to claim 2.

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