JP7603407B2 - Chair backrest - Google Patents

Description

This invention relates to a chair backrest equipped with a lumbar support device.

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 constant, and a lifting type, in which the height of the support pad can be adjusted. However, the lifting type lumbar support device is equipped with an operating member, and so how to position the operating member becomes an issue.

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 where 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 operating knobs are exposed from these slits.

On the other hand, Patent Document 2 discloses that in a backrest whose back surface is formed from a back shell body, a 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.

JP 2002-191462 A JP 2019-103675 A

In Patent Document 1, the support pad is elongated in the left-right direction, and so operation 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 seat while seated, the user must reach behind them and spread both hands out to the left and right to place them on the knobs. This tends to cause the arms to bend unnaturally, which raises concerns about poor operability.

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

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 spreading one's arms while seated, making it easy to operate and user-friendly.

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 of the support pad and improved operability.

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.

In the invention of claim 1, in the above basic configuration,
"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 forward or backward within the long hole, and a knob that is provided on the lifting body and positioned on the outside of the back shell body .
The structure is as follows.

As the support pad rises and falls, the relative height between the support pad and the long hole changes, but the long hole should overlap or extend below the lifting area of the support pad when viewed from behind.

As an example of developing claim 1 , claim 2 is as follows:
"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 a vertically long mounting hole into which the sleeve body is fitted."
The structure is as follows.

Furthermore, claim 2 states:
"The lifting body has an insertion part arranged inside the sleeve body so as to be movable up and down, and a guide part located in front of the insertion part and engaged 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 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.

Furthermore, as an example of developing claim 2 , claim 3 states:
"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.

The support pad supports the lower back of a seated person, so if the support pad is at the same height as 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 extends partially below it, so that the operating member can be easily lifted and lowered without having to bend the arm unnaturally.

When the support pad is in its lowest position and the long hole is below the support pad, the exposed part of the lifting/lowering operation part (the finger hook) is located below the support pad, so the lifting/lowering operation can be performed with the arms held behind the back and with little bending. This is therefore particularly suitable.

Regarding the lifting operation unit, various types of knobs that a person places his/her finger on can be used, but if a knob that protrudes on both the left and right sides of the long hole is used as in claim 1 , the knob can be firmly grasped and force can be applied to move it up and down, further improving operability. In addition, the knob can also prevent the part of the lifting body that fits into the long hole (the insertion part) from slipping out forward, which also simplifies the structure of the lifting operation unit.

It is possible to form the spine shell body as a one-part structure and directly form the long hole in it, but as in claim 2 , if the spine shell body is formed of a shell main body and a sleeve body and a long hole is formed in the sleeve body, the sleeve body can be made of a material different from the shell main body, making it easier to raise and lower the lifting and lowering operation part, and it is easier to attach and guide the lifting and lowering operation part while facilitating the molding of the shell main body.Therefore, it is realistic.

When the configuration of claim 2 is adopted, the protruding portion (guide portion, flange) of the lifting body is surrounded by the shell body and the sleeve body, so that the lifting operation portion (lifting body) can be prevented from falling in the front-rear direction and can be raised and lowered smoothly, and since the sleeve body, which is fitted into the shell body from the rear, also serves as the guide means, molding of the shell body is easy. Therefore, the lifting operation portion can be raised and lowered smoothly without compromising the ease of molding of the shell body.

In chairs equipped with a back shell, the back is also covered with a skin material. In other words, the entire backrest is covered with the skin material. This configuration gives the backrest a high fashionability. The invention of claim 3 is applied to the covered type, but since the skin material can be held down by the sleeve body, the skin material can be kept in a tight state.

Furthermore, if the knob of the lifting/lowering operation part hits the skin material, the movement becomes sluggish and the skin material becomes easily worn away. However, in the invention of claim 3 , the knob of the lifting/lowering operation part does not hit the skin material, so that deterioration of the smoothness of the lifting/lowering movement and wear of the skin material can be prevented.

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. In other words, the lifting/lowering operation part is raised or lowered by placing a finger on its rear end, so the back shell body has a tendency to rotate in the front-to-back 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.

In this respect, by adopting the configuration of claim 1 , 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.

1A is a perspective view seen from the front with the skin material omitted, FIG. 1B is a perspective view seen from the rear, and FIG. 1C is a side view showing an embodiment. 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 from the rear. FIG. 2A is a perspective view of a lumbar support device, and FIG. 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. (A) is an exploded perspective view of the entire lumbar support device viewed 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. FIG. 2 is a separated perspective view of the lifting body and the shell main body. FIG. 1A is a plan cross-sectional view taken at the middle portion between the top and bottom of the knob, and FIG. 1B is an exploded perspective view showing the lifting/lowering operation unit. FIG. 9 is a cross-sectional plan view taken along line IX-IX of FIG. 7 . FIG.

(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, etc., and as shown in Figure 1, comprises as basic elements a leg device 1, a seat 2, and a backrest 3. 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.

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 located on the front of it. An upwardly curved crescent-shaped lower bracket 8 and a back cover 9 located on top of it are located on the lower rear surface of the shell body 6. Furthermore, side covers 10 are attached to the rear surfaces of both the left and right ends of the lower bracket 8.

As shown in FIG. 2(C), the shell body 6 is formed in the shape of a shallow tray that opens forward, and has many reinforcing ribs formed inside. The back cushion 7 is placed 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.

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 the lifting and 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 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 that it can move up and down freely. Therefore, the back shell body is constituted by the shell body 6 and the sleeve body 16.

(2) Lumbar Support Device Next, the lumbar support device will be described. As shown in Figures 3 to 5, the lumbar support device includes the support pad 14 described above and a lifting/lowering operation unit 19 for moving it 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 a 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.

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 in side view and plan view. For example, as shown in Fig. 3(A) and (B), rearward-facing guide protrusions 25 are formed at four positions on the top, bottom, left, and right of the rear surface of the support pad 14, while a guide frame 26 into which the guide protrusions 25 fit is formed on the front surface of the shell main body 6 so as to be immovable left and right but movable up and down.

The guide grooves 27 that are open to the top, bottom, and rear are cut out and formed at the tips of the guide protrusions 25, while guide ribs 28 into which the guide grooves 27 of the guide protrusions 25 slide freely are formed inside the guide frame 26, as shown in FIG. 6, for example.

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 protrudes 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. With the boss portion 30 and the square recess 30a fitted together, the slider 22 is fixed to the head portion 29 with screws 21.

As shown in Figures 4(A) and 5(A), the slider 22 is formed in a rectangular shape that is long from side to side, and has positioning protrusions 31 on both the left and right sides, while the catch 24 has a pair of engaging claws 32 that are shaped like a V-shape, 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.

Therefore, the engagement between the rectangular projection 33 and the rectangular recess 30a keeps the catch 24 immovable to the left and right and immovable downward, and the left and right positioning projections 31 clamp the upper part of the catch 24 from the left and right, keeping the catch 24 immovable upward.

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

For example, as shown in Figures 4(A) and 5(A), the guide body 23 is formed in a square 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.

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

For example, as shown in Figures 4(A) and (C), a rack is formed by providing multiple engagement protrusions 48 for height adjustment on the left and right inner sides of the guide body 23, and the support pad 14 is held at the 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 Figure 7, a resin sheet backing plate 46 can be interposed between the back cushion 7 and the support pad 14. As shown in Figure 3(A), the support pad 14 has protruding ribs 14a that are shaped like a mountain when viewed from the side, located on both the left and right sides of the guide body 23.

As shown in Figures 4(A) and 5, the lifting body 20 has an inclined portion 49 that extends downward from the head portion 29, and a boss body 50 with a square cross section that protrudes rearward from the lower end of the inclined portion 49. On the other hand, the sleeve body 16 has a vertically elongated tubular portion 51 into which the boss body 50 slides freely, and a flange 52 that protrudes 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 held down by the flange 52.

For example, as shown in FIG. 7, the shell body 6 is curved in a forward-facing bulge in side view so that the part of the shell body that comes into contact with the lower back of a seated person is located at the very front, and is curved in a forward-facing concave shape in plan view. The support pad 14 is generally positioned in a part that juts out forward in side view, and the sleeve body 16 is also positioned in the curved part of the shell body 6.

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 front-to-rear thickness increases upward, thereby setting the sleeve body 16 in a gently backward-inclined position.

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 Fig. 4(A) and Fig. 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 to hold the sleeve body 16 immovable backward.

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.

For example, as shown in FIG. 4, a flange-shaped protruding portion 58 that protrudes 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 protruding portion 58 abuts or is in close contact with the front surface of the tube 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 protruding portion 58 abut or are in close contact with the left and right inner surfaces of the forward opening groove 54.

In this case, as shown in Figures 6 and 7, a forward-facing step 54b is formed in a portion of the forward-facing opening groove 54 below the widening portion 54a, while a backward-facing step 54c is formed as shown in Figures 6, 7 and 9, and the protruding portion 58 of the lifting body 20 is sandwiched between the front surface of the sleeve body 16 and the backward-facing step 54c, thereby guiding the up and down movement of the lifting body 20 (the lifting body 20 is guided as it rises and falls so as not to tip over in the front-to-back direction). In other words, by inserting the protruding portion 58 of the lifting body 20 into the groove formed by the sleeve body 16 and the backward-facing step 54c, the lifting body 20 is guided so as to rise and fall without tipping over in the front-to-back direction.

6 and 7, the vertical length (height) of the overhang 58 is slightly smaller than the combined vertical length of the widened portion 54a and the forward step 54b in the forward opening groove 54. Therefore, when the overhang 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 overhang 58 is raised after it hits the forward step 54b, the overhang 58 is positioned behind the rear step 54c. Therefore, when the sleeve body 16 is attached in this state, the lifting body 20 cannot descend to the lowest step, and the overhang 58 is held sandwiched between the sleeve body 16 and the rear step 54c from the front and rear.

(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 and lowered by smoothly moving the knob 15 up and down.

Because the support pad 14 and the knob 15 are separated in the front-to-back and up-down directions, if there were only one guide, the lifting body 20 would tend to tip over in the front-to-back direction when the knob 15 moves up and down, which could cause distortion and make it difficult to raise and lower smoothly. However, in this embodiment, the lifting body 20 can be raised and lowered smoothly without distortion 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 forward and backward but able to move up and down.

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 be lifted and lowered 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.

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

For example, as shown in FIG. 4(A), the lower end of the guide frame 23 is formed by the 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.

The slider 22 hits the lower frame 23a of the guide frame 23, determining the maximum lowering height of the lifting body 20. In this state, as shown in FIG. 7, the boss body 50 of the lifting body 20 is positioned 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 in a position that prevents it from slipping out of the forward direction.

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 then 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 can be attached first.

As in this embodiment, providing guide protrusions 25 on the support pad 14 prevents the support pad 14 from tipping forward and backward, allowing the support pad 14 to 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 is prone to problems. However, providing guide protrusions 25 allows the support pad 14 to be raised and lowered smoothly, regardless of the mounting height position relative to the lifting body 20.

In the above embodiment, the long 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 on the knob 15 that covers the long hole 17. In this way, as the knob 15 moves up and down, the cover portion 15a also moves up and down, so the long 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.

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 circle can be adopted. Also, the lifting operation unit does not necessarily need to have an inclined portion. The height adjustment means is not limited to stepwise height adjustment using an engaging claw as in the embodiment, but a stepless height adjustment mechanism using a damper or the like can also be adopted.

The present invention can be embodied in a backrest equipped with a lumbar support device. Therefore, it can be used industrially.

LIST OF REFERENCE NUMERALS 3 Backrest 6 Shell body 7 Back cushion 13 Cover material 15 Knob 16 Sleeve body 17 Slotted hole 19 Lifting operation section 20 Lifting body 22 Slider 23 Guide body constituting guide section 24 Catch body 29 Head 32 Engagement claw 48 Engagement protrusion 49 Inclined section 50 Boss body 51 Cylinder section 52 Flange 53 Opening of shell body 54 Forward opening groove 54a Widened section of forward opening groove 54b Forward step section 54c Rearward step section 58 Projecting section

Claims (3)

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. The back shell body includes a vertically long 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 a vertically long mounting hole 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. The back 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 an edge portion 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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