JP2006149681A - Backrest structure of chair - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a seated person to stably work in various postures according to the personal difference in the body size. <P>SOLUTION: The backrest structure of a chair comprises a backrest frame 2 connected to a seat 1 in such a way as can be locked, and a backrest 3 supported to the backrest frame 2. The backrest 3 comprises a backrest main part 3a attached to the backrest frame 2 and a backrest lower part 3b connected to the lower side of the backrest main part 3a in such a way as oscillatable in the front/rear direction and can be held at an arbitrary angle. The connection position 4 of the backrest main part 3a to the backrest lower part 3b is set higher than a backrest point 5 and lower than the position equivalent to the lower part of the thoracic vertebrae 14 of the seated person, and the backrest point 5 is set at the middle of the backrest lower part 3b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chair backrest structure. More specifically, the present invention relates to a chair backrest structure that is divided into a plurality of members and each member is independently displaceable.

  2. Description of the Related Art Conventionally, for the purpose of optimizing the shape of a backrest corresponding to individual differences in the physique of a seated person, there has been proposed a system in which the backrest is divided at substantially backrest points (see Patent Document 1). This is the support (central support) of the seated person's lumbar-chest transition site (roughly, the back part from the 9th thoracic vertebra (T9) to the 2nd or 3rd lumbar vertebra (L2 / L3) from the top) Element 41) and a lumbar-sacral support (pelvic support element 71) and a pivot pin 72 extending horizontally near the deepest or backrest of the lumbar region of the spinal bone at the lower end of the lumbar-chest transition support Are pivotably connected in the front-rear direction. Thus, by allowing the pelvic support element 71 to move back and forth relative to the central support element 41, it applies to the lumbar lordosis and lumbar spine kyphosis, and any possible state therebetween. I have to. It is intended to optimally apply the backrest to the lumbar and chest shapes of each spine.

  In addition, a structure has been proposed in which the seat back can be folded at an arbitrary position according to individual differences and preferences of the seated person (see Patent Document 2). This seat back has a built-in feed screw mechanism for adjusting the folding position and a feed screw mechanism for pushing the upper part of the seat back forward to adjust the folding position (folding height) of the backrest. At the same time, it is intended to realize a seat back shape that matches the individual differences and preferences of the seated person by covering the upper part of the backrest so as to cover forward.

  Furthermore, since there are significant differences in the shape and body shape of the operator's spine, it is impossible to satisfy all workers with the same shape of the backrest. In addition, the desired level of waist area stiffness or support is different for each person, and responds to different demands when the sitting user is doing different jobs, reclining a chair, or getting tired. I can't. Therefore, in order to meet these demands, the backrest is divided into an upper portion that supports the back and a lower portion that supports the waist, and the back support member is pivotally supported by the backrest frame at the pivot connecting portion, while the waist support member is A torsion spring is attached so as to urge the seated person toward the waist, and the lower end of the back support member and the upper end of the waist support member are pivotally connected by a pivot / sliding connection portion, thereby the backrest point can be set. A backrest structure that is biased by a spring force in a forward direction is proposed (see Patent Document 3).

Special table 2003-522571 JP 2000-23780 Special table 2001-522618

  However, all the conventional backrest structures correspond to individual differences in the physique of the seated person, and the backrest structure cannot be changed to a shape suitable for work in various postures. That is, there is a situation that the position corresponding to the backrest point on the back of the seated person moves back and forth according to the difference in the posture such as the upright posture (back tilt angle small) and the reclining posture (large back tilt angle). The conventional backrest structure does not correspond to this, and the backrest point important for supporting the back cannot be moved back and forth in accordance with the above-described difference in posture. Therefore, the conventional backrest structure has a problem that a support that can stably work in various postures cannot be obtained.

  Moreover, in the folding seat of the patent document 2, since the lower part of the backrest is connected to the seat, the middle folding position (the middle folding height) of the backrest is adjusted, or the upper side of the backrest is covered forward. Although it can be put out like this, it cannot take a rocking posture in which the entire backrest is tilted backward.

  Furthermore, in the method of Patent Document 3, since the backrest point is only urged by the spring in the direction to come forward, the backrest shape, particularly the angle, can be changed according to the state of the back of the seated person. Cannot be held, and when the seat is too large for the seated person or when the seat is shifted forward, there is a problem that the waist cannot be reliably supported.

  An object of the present invention is to provide a chair backrest structure that can cope with individual differences in the physique of a seated person and can stably work in various postures. It is another object of the present invention to provide a chair backrest structure that reliably supports the waist even when the seat is too large for a seated person or when the seat is shifted forward.

  In order to achieve such an object, the present inventor has conducted various studies and studies on chairs having a function of being able to perform various postures in order to cope with a variety of work in the office. As a result, the backrest and the backrest point of the thoracic vertebra part (fixed part) It is divided into lumbar parts (movable parts) that include the lumbar part, and by moving the lumbar part back and forth by rotating, it can respond to multiple postures and change the part of the lumbar part that corresponds to the seated person to cope with individual body type differences It came to know that is possible.

  That is, as shown in FIG. 3, the spine is composed of a cervical vertebra, a thoracic vertebra, a lumbar vertebra, a sacrum, and a coccyx, and these have various shapes depending on a person. The lumbar spine has a large movable range among the backbones related to the chair, and the thoracic vertebra has a low mobility because its movement is restricted by the rib cage. However, the eleventh and twelfth thoracic vertebrae on the lower side of the thoracic vertebra have a degree of freedom because they are in a free state. On the other hand, the first lumbar vertebra has the greatest mobility among the lumbar vertebrae, and attention was paid to the connecting portion between the thoracic vertebra and the lumbar vertebra when changing the posture.

  In addition, the lower part of the backrest is put forward to support the pelvis. It is possible to prevent the pelvis from being tilted backward and to keep the back of the pelvis and maintain a good posture. By lowering the lower part of the back to the person who is a short woman and has not used the back in the chair in the past, the depth of the seat surface is shortened, and it is possible to use the back effectively (FIG. 4D).

  Furthermore, by extending the lower back of the back and widening the body flexion, blood flow in the lower limbs is improved, fatigue is less likely, and swelling is prevented. Furthermore, a more relaxed feeling can be obtained than a normal backrest angle, and a resting posture can be taken. Furthermore, it is possible to support the body by filling the gap between the chair and the body by adjusting the lower part of the backrest even for the sliding sitting often seen in the sitting posture (FIG. 4 (e), (F)).

  Furthermore, by moving a portion (shoulder support) that supports the shoulder portion of the upper portion of the backrest, more postures are possible. The backrest structure that supports the shoulder by using a conventional back bend and mechanism makes it easier to work, but does not support resting posture or stretching, and feels cramped. Therefore, it is possible to cope with multiple postures by making the back upper part corresponding to the shoulder movable (FIGS. 4B and 4C).

  The present invention has been achieved on the basis of such knowledge, and in a chair back structure including a back frame that is rockably connected to a seat and a back supported by the back frame, the back is attached to the back frame. The main portion and a lower back portion connected to the lower side of the main back portion so as to be swingable in the front-rear direction and capable of being held at an arbitrary angle. The connecting position between the main back portion and the lower back portion is the backrest. The position is set above the point and below or below the position corresponding to the lower part of the seated person's thoracic vertebra, and the backrest point is set at an intermediate position below the backrest.

  Here, the connecting position of the main part of the backrest and the lower part of the backrest is set above the backrest point, but if the connecting position that is the axis of swing is too high, the amount of movement of the lower end of the backrest will be too large. So it's not realistic. Therefore, the connecting position is above the backrest point and corresponding to or below the seated person's lower thoracic vertebra, preferably from the third lumbar vertebra to the tenth thoracic vertebra, more preferably from the second lumbar vertebra to the eleventh. Between the thoracic vertebrae, most preferably near the boundary between the thoracic and lumbar vertebrae.

  Furthermore, the present invention preferably includes a backrest upper portion (shoulder support portion) connected to the upper side of the backrest main portion so as to be swingable in the front-rear direction.

  Moreover, it is preferable that this invention is provided with the fixing means which fixes the angle of the backrest lower part with respect to the backrest main part.

  Thus, the chair back structure according to the present invention is configured as described above, so that it is possible to cope with individual differences in the physique of the seated person and also to accommodate multiple positions of the seated person. Further, even when the seat is too large for the seated person or when the seat is shifted forward, the lower backrest can be moved forward to reliably support the waist. Because of these, not only can a person with a standard physique sit in a standard posture, but also a seat with a variety of physiques and various seating postures can be handled well, improving seating comfort and usability. Can be made. Moreover, it can be used in a state in which the bending angle of the backrest is adjusted to a desired angle, and this makes it possible to improve the comfort and usability of the chair.

  In this case, it is preferable to set the connecting position between the main portion of the backrest and the lower portion of the backrest between the third lumbar vertebra and the tenth thoracic vertebra, as in the chair backrest structure described in claim 2. The back can be supported more firmly, and the comfort and convenience of use can be further improved.

  Further, in the chair backrest structure according to claim 3, the backrest upper portion connected to the upper side of the main portion of the backrest so as to be swingable in the front-rear direction is provided, so that it is possible to cope with various physiques and sitting postures. Become.

  Furthermore, in the chair backrest structure according to claim 4, since the fixing means for fixing the angle of the lower backrest with respect to the main portion of the backrest is provided, the angle of the lower backrest can be more reliably fixed, and the usability is further improved. Can be made.

  Hereinafter, the configuration of the present invention will be described in detail based on the best mode shown in the drawings.

  1 and 2 show an embodiment of the chair backrest structure of the present invention. The chair backrest structure (hereinafter simply referred to as a backrest structure) includes a backrest frame 2 that is rockably coupled to a seat 1 and a backrest 3 that is supported by the backrest frame 2, and the backrest 3 is a backrest frame 2. A backrest main portion 3a attached to the backrest, and a backrest lower portion 3b connected to the lower side of the backrest main portion 3a so as to be swingable in the front-rear direction and to be held at an arbitrary angle. The backrest main portion 3a The connecting position 4 with the backrest lower part 3b is set above the backrest point 5 and at or below the position corresponding to the lower part of the thoracic vertebra 14 of the seated person, and the backrest point 5 is set at the intermediate position of the backrest lower part 3b. I am doing so. In the present embodiment, a backrest upper portion (for example, a shoulder support portion) 3c is provided on the upper side of the backrest main portion 3a so as to be swingable in the front-rear direction.

  The back frame 2 is attached to the seat receiving member 6 so as to be tiltable. The backrest main portion 3 a of the backrest 3 is fixed to the backrest frame 2. Here, the backrest main portion 3a is fixed to the backrest frame 2 by welding or the like. However, there is no reason to be necessarily fixed, and in some cases, it may be supported to some extent, such as being pivotably attached by a pivot bearing or the like.

  Note that the backrest point 5 is defined in JIS, but is generally "a point that is most forward in the vicinity of the lumbar portion of the backrest surface", and generally the vicinity of the third lumbar vertebra 15b of the seated person. Refers to the position to support.

  In this embodiment, the backrest frame 2 and the main portion 3a of the backrest supported by the frame 2 are fixed. However, depending on the case, the vertical position of the entire backrest 3 can be adjusted, and the difference in the physique of the seated person can be adjusted. Accordingly, it is preferable that the height of the backrest point 5 can be adjusted.

  As means for connecting the backrest lower portion 3b to the backrest main portion 3a so as to be swingable in the front-rear direction, for example, a hinge 7 is employed. The hinge 7 is fastened via a washer or the like with a bolt (not shown) penetrating in a state where a frame-shaped frame 8 and an I-shaped frame 9 accommodated in the frame 8 are overlapped. A plate 10 for attachment is welded to each of the frames 8 and 9, and the plate 10 portion is fixed to the backrest main portion 3a or the backrest lower portion 3b using fixing means such as rivets and bolts. .

  The connecting position 4 between the backrest main portion 3 a and the backrest lower portion 3 b is set above the backrest point 5. Here, if the connection position 4 is too high, the amount of movement of the lower end of the backrest 3 becomes too large, which is not realistic. Therefore, the connecting position 4 is located above the backrest point 5 and below or below the seated person's thoracic vertebra 14, more specifically between the third lumbar vertebra 15b to the tenth thoracic vertebra 14c, preferably The second lumbar vertebra 15c to the eleventh thoracic vertebra 14a are most preferably near the boundary between the thoracic vertebra 14 and the lumbar vertebra 15 (FIG. 3).

  These positions are determined based on, for example, a standard sitting posture of a seated person having a standard physique. However, since the positions of the thoracic vertebra 14 and the lumbar vertebra 15 do not change greatly even if the seated person's physique and sitting posture are different, the connection position 4 is determined based on the standard sitting method of the seated person of the standard physique. There is no inconvenience.

  The backrest structure has a fixing means 11 for fixing the angle of the backrest lower portion 3b with respect to the backrest main portion 3a. The fixing means 11 is, for example, a lock mechanism that connects the backrest lower portion 3 b to the backrest frame 2. As the lock mechanism, in the case of this embodiment, a known lock mechanism generally called a mechanical lock device is used. Although the detailed structure of this mechanical lock is not shown, the movement of the rod is constrained by tightening a coil spring that winds around a rod that can freely enter and exit the housing, and the positional relationship between the rod and the housing. It is a mechanism to fix. One of the housing and the rod is rotatably connected to the backrest frame 2, while the other is rotatably connected to the backrest lower part 3b, so that it can be fixed to the backrest main portion 3a at an arbitrary angle. Yes. Here, the coil winding and relaxation are performed by lever operation via a wire of the control cable. The operation lever is attached to, for example, the lower right corner, the lower left corner of the backrest lower portion 3b or the vicinity thereof in order to facilitate the operation in the sitting state. By operating the lever, the movement of the rod of the lock mechanism is restricted or released, so that the expansion and contraction is allowed or fixed. The backrest lower part 3b swings forward by extending the lock mechanism, and the backrest lower part 3b swings rearward by contracting the lock mechanism. The backrest lower portion 3b can be held at an arbitrary angle with respect to the backrest main portion 3a by fixing the lock mechanism to an arbitrary length.

  The locking mechanism is not limited to the locking mechanism of the present embodiment, and for example, a mechanism that also serves as a reaction force mechanism such as a gas spring with a locking mechanism can be employed.

  The backrest lower part 3b is bent so that the center in the vertical direction is located at the forefront. This most forward point is the backrest point 5. As shown in FIGS. 5 and 6, when the backrest lower part 3b is swung forward, the lower part of the backrest lower part 3b can favorably support the seated person's waist. Although the bending angle of the backrest lower part 3b may be fixed, as shown in FIG. 8, the bending angle of the backrest lower part 3b may be adjustable.

  Similarly to the backrest lower portion 3b, the backrest upper portion 3c is coupled to the backrest main portion 3a by, for example, a hinge 7 so as to be swingable in the front-rear direction. Like the hinge 7 of the lower backrest 3b, the hinge 7 is a bolt (not shown) penetrating through a gate-shaped frame 8 and an I-shaped frame 9 accommodated in the frame 8 via a washer or the like. And tightened. A plate 10 for attachment is welded to each of the frames 8 and 9, and the plate 10 portion is fixed to the backrest main portion 3a or the backrest upper portion 3c using fixing means such as riveting and bolting. .

  The backrest upper portion 3 c is held at an arbitrary angle with respect to the backrest main portion 3 a by the frictional force of the hinge 7. That is, the angle adjustment of the backrest upper part 3c is performed by overcoming the frictional force of the hinge 7 and swinging the backrest upper part 3c. However, the angle may be fixed by connecting to the backrest frame 2 using the same fixing means 11 as the backrest lower part 3b.

  The backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c are curved so that the left and right sides protrude forward and the center retracts backward as viewed from the top and bottom, and can be supported so as to wrap the back of the seated person. it can.

  The backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c are made of, for example, a flexible material. In this embodiment, these are shape | molded, for example with resin, such as a polypropylene and nylon. However, the resin that becomes the backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c is not limited to these, and the backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c may be formed of a material other than the resin. . Further, the material may not be a flexible material.

  In the present embodiment, as shown in FIG. 2, the division of the backrest 3 is performed by a linear dividing line. However, the present invention is not limited to this, and depending on the case, a slightly curved dividing line may be used. good.

  In this backrest structure, as described below, the backrest 3 can be adjusted according to various postures taken by the seated person, and can correspond to the physique difference of the seated person.

  The angle of the backrest lower portion 3b relative to the backrest main portion 3a can be arbitrarily changed by pushing or pulling the backrest lower portion 3b forward or rearward with the operation lever of the lock mechanism opened. And the position of the backrest lower part 3b is fixed by releasing the operation lever of the lock mechanism at an arbitrary position. Similarly, when the backrest 3c is also provided with a locking mechanism, the backrest 3c can be moved by operating the operation lever so that the backrest 3c swings in the front-rear direction around the connecting portion near the upper end edge of the backrest main portion 3a. It can be fixed after being set to an arbitrary position. As a result, coupled with the locking operation of the back frame 2 with respect to the seat 1, the backrest shape is changed according to various postures such as an upright posture, a rocking posture, and a stretching posture in addition to a normal working posture, and further, a seated person The backrest point 5 is appropriately moved in accordance with individual differences in the physiques, and changes according to individual differences are made possible.

  Further, regardless of the inclination of the backrest frame 2, the bending angle of the backrest lower portion 3b can be maintained by operating the lock mechanism. For this reason, the bending angle with respect to the backrest main portion 3a can be adjusted to a desired angle or an optimum angle.

  As shown in FIG. 3, the spine 12 includes a cervical vertebra 13, a thoracic vertebra 14, a lumbar vertebra 15, a sacrum 16, and a tailbone 17, which have various shapes depending on a person. The lumbar spine 15 has a large movable range among the backbones 12 related to the chair, and the movement of the thoracic vertebra 14 is limited because the movement is restricted by the rib cage. However, since the eleventh and twelfth thoracic vertebrae 14a and 14b below the thoracic vertebra 14 are in a free state, there is a degree of freedom. On the other hand, the first lumbar vertebra 15a has the greatest mobility among the lumbar vertebrae 15, and attention is paid to the connecting portion between the thoracic vertebra 14 and the lumbar vertebra 15 in changing the posture. Dividing the backrest 3 into a backrest main portion 3a corresponding to the thoracic vertebra 14 and a backrest lower portion 3b corresponding to the lumbar vertebra 15 and moving the backrest lower portion 3b back and forth by swinging can cope with multiple postures. Furthermore, it is possible to cope with the physique difference of the seated person by moving the backrest lower part 3b back and forth by swinging (FIGS. 4A to 4F, etc.).

  Furthermore, the pelvic support is provided by swinging the lower backrest 3b forward. It is possible to prevent the pelvis from being tilted backward and to keep the back of the pelvis and maintain a good posture. Even if you are a low-profile woman and you have not used your back in the chair 3 so far, swinging the lower back 3b forward reduces the depth of the seat 1 and effectively reduces the back 3. It can be used (FIGS. 4D and 5). At this time, the backrest lower portion 3b has a bent or curved shape (a shape of a dogleg) projecting forward at an intermediate portion in the vertical direction so as to form a backrest point 5 in the middle of the backrest main portion 3a. Therefore, the lower part of the backrest 3b below the backrest point 5 hits and supports the lumbar vertebra 15 part. In the present embodiment, the bending angle of the backrest lower part 3b is fixed, but it is more preferable that the bending angle of the backrest lower part 3b is adjustable (FIG. 8).

  Furthermore, the lower backrest 3b is swung forward and the bending angle of the body (the angle indicated by the curved arrows in FIGS. 4 (e) and 4 (f)) is widened to improve blood flow in the lower limbs, prevent fatigue and prevent swelling. effective. Furthermore, a relaxed feeling can be obtained from the normal angle of the backrest 3, and a resting posture can be taken. Furthermore, by adjusting the position of the backrest lower part 3b, which is often seen in a sitting position, the gap between the chair and the body can be filled and the body can be supported (FIG. 4 ( e), (f)).

  Furthermore, by moving a portion (shoulder support) that supports the shoulder portion of the backrest upper portion 3c, more postures are possible. The backrest structure that supports the shoulder by using a conventional back bend and mechanism makes it easier to work, but does not support resting posture or stretching, and feels cramped. In the present invention, it is possible to cope with multiple postures by making the backrest upper portion 3c corresponding to the shoulder movable (FIGS. 4B and 4C).

  In addition, the position corresponding to the backrest point 5 on the back of the seated person moves back and forth according to the difference in the posture such as the upright posture (small backward tilt angle) and the reclining posture (large backward tilt angle). If it is the structure of invention, since the backrest point 5 important for support of a back can be moved back and forth, it can respond also to differences, such as an upright attitude | position and a reclining attitude | position.

  Further, as shown in FIG. 7, by moving the backrest lower portion 3b back and forth, it is possible to cope with an S-shaped person or an I-shaped person with a spine 12 shape. In FIG. 7, the case where the spine 12 shape corresponds to an S-shaped person is indicated by a solid line, and the case where the spine 12 corresponds to an I-shaped person is indicated by a two-dot chain line.

  Here, FIG. 9 shows a conventional backrest structure of a chair. (A) shows a basic posture and (b) shows a reclining posture. In this backrest structure, as shown in (c), a seated person with a small physique cannot use the backrest because the back does not reach the backrest. Further, as shown in (d), even when the back reaches the backrest, there is a gap between the backrest and the waist when sliding and sitting. Further, as shown in (e), if the back is warped, there is no shoulder support and a burden is applied to the neck and shoulder. On the other hand, as shown in (f), it is difficult to stretch those with shoulder support. That is, it corresponds to two or three kinds of postures, but does not correspond to more postures.

  On the other hand, in the present invention, as shown in FIG. 10, first, by widening the bending angle of the body ((a) → (b)), abdominal compression is reduced, breathing is facilitated, Blood flow also improves. Conventional chairs could only be widened by reclining the bending angle. Moreover, as shown in (c), the burden on the waist can be reduced by supporting the pelvis and the lumbar spine 15 by the lower backrest 3b.

  Further, by moving the backrest upper portion 3c, more postures are possible. For example, it is possible to support (1) shoulder support in a personal computer working posture during uprighting or reclining, (2) stretching posture, and (3) resting posture.

  For example, when working on a PC with the backrest 3 tilted backward, the shoulder is bent forward (FIG. 11 (a)) compared to when the backrest 3 has a small backward tilt (FIG. 11 (a)). This can be accommodated by moving 3c forward (FIG. 11 (b)). Then, the bending angle can be further widened to facilitate the work (FIG. 11 (c)). Furthermore, it can also correspond to a stretch posture (Fig. 12 (a)) that extends to the back, and further, the backrest frame 2 is tilted backward from this state, the lower backrest 3b is moved further forward, By using the backrest upper part 3c as a headrest, it is possible to cope with a resting posture (FIG. 12B). Thus, it can cope with various postures satisfactorily.

  In addition, by using the chair with the flexion angle of the backrest 3 increased, for example, when the backrest frame 2 is tilted and the entire backrest 3 is reclined, the back muscles can be stretched more, and the back stretching effect can be further enhanced. Obtainable.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention.

  For example, in the above description, although not shown, a cushion material is attached to the front surface of the backrest 3 as necessary, and the top is covered with a skin member. Of course, the backrest 3 may be composed of a frame material and a material such as a mesh or film stretched inside, and the mesh and frame material may be covered with a skin material, or in some cases a cushion material may be used. Sometimes it is packed.

  Further, the lock mechanism is not limited to a means with linear displacement, and for example, a cam mechanism or a link structure may be used, or a smooth movement may be obtained by using these together with a return spring. . In the lock mechanism using the cam structure, the bending angle of the backrest lower portion 3b with respect to the backrest main portion 3a can be adjusted steplessly by allowing the rotation angle of the cam plate to be fixed at an arbitrary angle. Further, by making the shape of the cam portion of the cam plate a polygon, the bending angle can be changed stepwise.

  Further, in the above description, the backrest frame 2 is tilted backward to incline the entire backrest 3, and the bending angle of the lower backrest 3b is increased so that, for example, reclining, the seated person's back muscles can be further extended. It can also be made to be able to obtain the back stretch effect more.

  In the above description, the backrest 3c is a member that supports the scapula portion of the seated person, but may be a member that supports the scapula to the head, or a headrest that supports the head. good.

  Furthermore, in the above description, the backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c are each constituted by separate members, but in some cases, these may be integrally formed by the same member. In this case, it is conceivable to make the backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c swingable by a resin hinge. In addition, as the resin hinge, for example, a resin hinge formed by using a resin that is integrally formed with the backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c and that is more flexible than the resin that is the material thereof. In addition, it is possible to apply a hinge that is formed integrally with the backrest main portion 3a, the backrest lower portion 3b, and the backrest upper portion 3c, and is made flexible by making the wall thickness thinner than these.

  In this embodiment, the locking mechanism is operated by an operation lever provided at a position where the seated person can easily operate, so that the position of the lower backrest 3b or the upper backrest 3c is fixed. An electric motor may be provided, and the fixed position may be changed by adjusting the displacement amount of the lock mechanism electrically by starting and stopping the electric motor by a switch operation.

  In addition, a bag that expands and contracts by a fluid is provided as a locking mechanism, and the bag is interposed between the backrest frame 2 and the backrest lower portion 3b or the backrest upper portion 3c, so that fluid such as air is injected into the bag or The bag may be inflated or contracted by suction to tilt the backrest lower part 3b or the upper part, that is, change the bending angle.

  In the chair according to the present embodiment, the seat 1 and the back frame 2 are swingably attached to the seat receiving member 6 provided on the pedestal 19, while the back frame 2 and the seat receiving member 6 are interposed between them. Is provided with a reaction force mechanism 18 and tiltable by interlocking the seat 1 and the backrest 3. In the case of the present embodiment, the backrest 3 includes a backrest main portion 3a attached to the backrest frame 2, a backrest lower portion 3b attached to a lower end of the backrest main portion 3a so as to be swingable in the front-rear direction, and an upper end of the backrest main portion 3a. It is divided into three members with a backrest upper portion 3c attached to be swingable in the front-rear direction. Here, the backrest upper part 3c that supports the upper part of the thoracic vertebra 14 is provided. However, the backrest upper part 3c is not necessarily required, but it is preferable to provide it in correspondence with various postures.

  A front portion of the seat 1 is attached to a seat receiving member 6 fixed to the pedestal 19 by a connecting pin 20 so as to be swingable. Further, the lower end of the backrest frame 2 is attached to the center of the seat receiving member 6 by a connecting pin 21 so as to be swingable. A reaction force mechanism 18 such as a compression coil spring is provided in a compressed state between the front portion of the seat receiving member 6 and the lower end of the backrest frame 2, and constantly urges the backrest frame 2 to stand up. Further, a gas spring 22 with a lock mechanism is provided between the rear end portion of the seat receiving member 6 and the center portion of the backrest frame 2. The gas spring 22 is connected to the rear end portion of the seat receiving member 6 by a connecting pin 23 and to the central portion of the backrest frame 2 by a connecting pin 24. The gas spring 22 constitutes a triangular link mechanism together with the seat receiving member 6 and the backrest frame 2, and when the length of the gas spring 22 can be changed, the backrest frame 2 can tilt, but the gas spring 22. When the length is fixed, the backrest frame 2 cannot be tilted. That is, the angle of the backrest 3 can be locked by fixing the length of the gas spring 22. The length of the gas spring 22 is fixed or released by operating a lever (not shown).

It is a conceptual diagram which shows an example of embodiment of the backrest structure of this invention. It is a rear view which shows a backrest. It is a figure for demonstrating the structure of a spine. It is a figure for demonstrating that it can respond | correspond to various attitude | positions, (a) is a figure which shows a basic attitude, (b) is a figure which shows a mode that the backrest upper part is rock | fluctuated forward and a shoulder part is supported in a backward inclination attitude | position. (C) is the figure which shows the state which rock | fluctuated the backrest upper part back so that the upper part of the backrest did not become obstructive in a stretch posture, (d) is rocking | fluctuating the lower backrest part forward with respect to the seated person with small physique The figure which shows a mode of supporting a waist part, (e) is a figure which shows a mode of swinging a backrest lower part and a backrest upper part forward, and supporting a waist part and a shoulder part in the state of sliding, (f) is a backrest in a reclining posture It is a figure which shows a mode that a lower part and a backrest upper part are rock | fluctuated forward, and a waist | hip | lumbar part and a shoulder part are supported. The figure shows a case where a seated person with a small physique is used, (a) is a view before adjusting the position of the lower backrest, and (b) is a state of supporting the waist by swinging the lower backrest forward. FIG. A case where the seated person is slidingly sitting is shown, (a) is a state before adjusting the position of the lower backrest, (b) is a state where the lower backrest is swung forward to support the waist. FIG. It is a side view which shows a mode that the backrest lower part is rock | fluctuated and the shape as the whole backrest is changed. It is a side view which shows a mode that the bending angle of the backrest lower part was made adjustable. The conventional backrest structure is shown, (a) is a diagram showing a basic posture, (b) is a diagram showing a reclining posture, (c) is a diagram showing how a seated person with a small physique is used, and (d) is a sliding seat The figure which shows a mode that it is doing, (e) is a figure for demonstrating a mode that there is no support of a shoulder part in a reclining attitude | position, (f) is a figure which shows a stretch attitude | position. It is a figure for demonstrating that it can respond to various attitude | positions, (a) is a figure which shows a basic attitude, (b) is a figure which shows a mode that the bending angle was expanded, (c) is a mode that supports a waist | hip | lumbar part by a backrest lower part FIG. It is a figure for demonstrating that it can respond to various attitude | positions, (a) is a figure which shows a back leaning attitude | position, (b) is a figure which shows a reclining attitude | position, (c) expands a bending angle further from the state of (b). FIG. It is a figure for demonstrating that it can respond to various attitude | positions, (a) is a figure which shows a stretch attitude | position, (b) is a figure which shows a resting attitude | position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Seat 2 Backrest frame 3 Backrest 3a Backrest main part 3b Backrest lower part 3c Backrest upper part 4 Connection position 5 Backrest point 11 Fixing means 14 Thoracic vertebra 14
14c 10th thoracic vertebra 15b 3rd lumbar vertebra

Claims (4)

  A backrest structure of a chair comprising a backrest frame that is rockably coupled to a seat and a backrest supported by the backrest frame, wherein the backrest is attached to the backrest frame, and a backrest main portion that is attached to the backrest frame and a lower side of the backrest main portion. A lower backrest connected to be swingable in the front-rear direction and held at an arbitrary angle, and the connecting position of the main backrest and the lower backrest is above the backrest point and below the thoracic vertebra of the seated person The chair backrest structure is characterized in that the backrest point is set at a position corresponding to or below the position and the backrest point is set at an intermediate position below the backrest.   2. The chair backrest structure according to claim 1, wherein a connecting position between the backrest main portion and the lower backrest portion is set between the third lumbar vertebra and the tenth thoracic vertebra.   The chair backrest structure according to claim 1 or 2, further comprising a backrest upper portion connected to an upper side of the main backrest portion so as to be swingable in the front-rear direction. The chair backrest structure according to any one of claims 1 to 3, further comprising fixing means for fixing an angle of the lower portion of the backrest with respect to the main portion of the backrest.

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