chair

Abstract

This invention discloses a back support device that can stably hold the body even when the seated person tilts their upper body forward or backward. [Solution] The back support device 5 has a pad unit 14 and a lifting mechanism. The pad unit 14 has an upper pad 37 that supports the sitter's lower back, a lower pad 38 that supports the sacrum (or pelvis) of the sitter, and a base body 39 to which the lower pad is attached. The upper pad 37 has a main body 37a and left and right foot portions 37b and is formed in a gate shape, and the lower pad 38 is arranged in a state surrounded by the upper pad 37. The upper pad 37 can tilt backward against elasticity, and the main body 37a can be bent and deformed against elasticity. The posterior surface of a person's torso is connected in a continuous line at the sacrum and vertebrae, while the lower pad 38 and upper pad 37 are narrow in width, so the sitter is maintained in a stable posture even if their physique is different.

Description

Technical Field

[0001] The present invention relates to a chair having a back support device disposed behind a backrest.

Background Art

[0002] In chairs provided with a backrest, it has been proposed many times to provide a back support device that supports the lumbar region and pelvis of a seated person from behind. In particular, with respect to the driver's seat of an automobile, the back support device has also been devised so that a driver can drive for a long time without getting tired.

[0003] As an example, Patent Document 1 discloses a technique in which a lumbar support plate that supports a seated person at the height of the lumbar vertebra, a shoulder support plate that supports the shoulders of the seated person, and a pelvis support plate that supports the pelvis of the seated person are vertically separated and arranged inside a cushion material that constitutes a seat, and the shoulder support plate and the pelvis support plate are moved in the front-rear reverse direction by a handle operation.

[0004] In Patent Document 1, the left-right lengths of the lumbar support plate and the pelvis support plate are the same. When the seated person moves the shoulder support plate forward relative to the pelvis support plate, the upper body of the seated person is held in a posture of being slightly raised. When the shoulder support plate is moved backward relative to the pelvis support plate, the upper body of the seated person is held in a posture of being slightly reclined. And in any case, since the pelvis and the vertebra are supported, it can be said that the waist and the pelvis are held in a stable posture and fatigue can be suppressed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Now, when an office worker sits in an office chair and performs their duties, they may tilt their upper body to the left or right, or twist it horizontally. In a reclining office chair with a backrest that tilts backward, the upper body may also twist to the left or right while leaning back. While car drivers generally maintain the same posture while driving, office chairs are characterized by the fact that occupants often move their upper bodies significantly. Therefore, as part of improvements to office chairs, some designs are being made to allow the backrest to deform in accordance with the twisting motion of the body.

[0007] Furthermore, considering Patent Document 1 from the perspective of an office chair, in Patent Document 1, the left and right lengths of the lumbar support plate and the pelvis support plate are the same and are almost the same dimensions as the left and right width of the seat. Therefore, if it is applied as is to an office chair, there is a concern that the lumbar support plate and the pelvis support plate will press too hard against parts of the sitter's lower back and pelvis, making the sitter more likely to feel pressured.

[0008] Furthermore, the back of a person's torso has high resistance to pressure (compression resistance) at the vertebral region, but the resistance to pressure decreases as it moves towards the flank. Therefore, in configurations such as Patent Document 1, where the lumbar support plate and pelvis support plate extend across the entire length of most seats, if applied to a thin backrest structure such as a mesh-type backrest, a strong compressive force may be applied to the area near the flank on the back of the torso, potentially causing pain to the occupant.

[0009] Furthermore, considering the pelvis support described in Patent Document 1, when we look at the human skeleton, the vertebrae are connected to the sacrum, and the sacrum is located in the middle of the left and right sides of the pelvis and is supported by the pelvis. However, the vertebrae and sacrum are connected in a long vertical direction, and the posterior surfaces of the vertebral area and the posterior surface of the sacrum area are continuous and there is no individual difference in their anterior-posterior position. On the other hand, the posterior surface of the pelvis is located on both the left and right sides of the sacrum. Therefore, there is a concern that a gap may form between the pelvis support plate and the sacrum due to individual differences in the size and shape of the pelvis and the sacrum, as well as individual differences in the amount of flesh in the pelvic area and the sacrum area, resulting in incomplete support of the sacrum.

[0010] The present invention was made against this backdrop, and in particular with respect to office chairs, it aims to disclose a structure that can comfortably support the sitter from behind, even when the backrest is thin. [Means for solving the problem]

[0011] The present invention comprises many components, the typical of which is specified in each claim. Of these, the invention of claim 1 constitutes a broader concept. "A chair in which a back support device is positioned behind the backrest, capable of supporting the sitter at both the height of the pelvis and a height above it, The aforementioned back support device has a lower pad capable of supporting the sacrum or pelvis of the seated person, and an upper pad capable of supporting the seated person at the height of the vertebrae, with the left and right widths of the lower pad and the upper pad being different. This is the structure.

[0012] The invention of claim 2 is an extension of claim 1, "The lower pad is formed to be narrower than the upper pad." This is the structure.

[0013] As an example of the extension of claim 2, in claim 3, "The width of the aforementioned lower pad is such that it supports only the sacrum of the seated person and does not extend to the ilium." This is the configuration that is being adopted.

[0014] The invention of claim 4 is an extension of claim 2 or 3, "The upper pad has a main body that supports the seated person's body and left and right foot portions that extend downward from its left and right sides, and the lower pad is positioned between the left and right foot portions of the upper pad, with a gap between the main body of the upper pad and the lower pad." This is the structure.

[0015] The invention of claim 5 is an extension of any of claims 1 to 3, "The base end of the lower pad and the left and right foot portions of the upper pad are connected to a common base body, which is attached to the back support columns located in the left and right middle sections behind the backrest, either in a height-adjustable or non-height-adjustable manner." This is the structure.

[0016] The invention of claim 6 is also an example of any of claims 1 to 3, "The upper and lower pads, when viewed from the front, have a curved shape with their left and right side edges bulging outward, and their width narrows downwards." This is the structure.

[0017] The invention of claim 7 is an extension of claim 4, "The upper pad, including the main body and the foot portion, is curved in a forward-bulging shape when viewed from the side, so that the gap is at the very front." This is the structure. [Effects of the Invention]

[0018] The pain felt when a human body is subjected to an external force varies depending on the body part. The pressure resistance against a backward pressure is different between the lumbar region and the pelvic region. In the invention of claim 1, even when the backrest is thin and the contact feeling of the pad portion on the seated person is large, by making the left - right widths of the upper pad and the lower pad different, it is possible to accurately support the seated person without them feeling pain.

[0019] Now, when a seated person is performing office work such as operating a personal computer, they may adopt a posture where they lift their back off the backrest, a posture where they slightly recline their upper body and lean their back against the backrest, or a posture where they lean their upper body forward. In any case, it is preferable that the pelvis and the sacrum are maintained in a stable posture. That is, it is preferable that the pelvis and the sacrum are maintained in a posture upright from the seat surface regardless of the posture of the waist or the back. (Otherwise, it is likely to cause a burden on the vertebrae and lead to fatigue, low back pain, etc.).

[0020] As described above, the pressure resistance against an external force from the back is large (insensitive) at the dorsal part of the pelvis and the dorsal part of the sacrum, while at the dorsal part of the waist, the pressure resistance becomes smaller (more sensitive) towards the flanks. Therefore, as in claim 2, when the lower pad is made narrow and the upper pad is made wide, it is possible to accurately support without causing pain while making the back support device as compact as possible.

[0021] In particular, when adopting a configuration as in claim 3 where only the sacrum is supported by the lower pad, it is suitable because it can prevent the burden on the waist while firmly maintaining the posture of the pelvis and the sacrum even if the physique of the seated person varies.

[0022] When the upper pad is formed in a U - shape as in the invention of claim 4, while ensuring its function for the lower pad, it is possible to effectively utilize the dead space on both the left and right sides of the lower pad to make the back support device thinner. Also, since the left and right feet of the upper pad and the lower pad are arranged side - by - side in the left - right direction, it can present a neat appearance and contribute to improving the commercial value from the design aspect.

[0023] As described in claim 5, by deriving the lower pad and the upper pad from a common base body, the overall design can be made more compact, and the appearance can be made neater and more aesthetically pleasing.

[0024] As described in claim 6, by forming the upper and lower pads in a shape that tapers downwards when viewed from the front, the base body can be set to the minimum necessary width, promoting the compactness of the back support device, while the lower and upper pads can be given the necessary width to maintain their function. In addition, it presents a clean appearance and is aesthetically pleasing.

[0025] As described in claim 7, by curving the lower and upper pads in a side view, it is possible to prevent them from pressing against specific areas on the rear of the seated person, and they also offer excellent adaptability to changes in the seated person's posture and differences in body shape. [Brief explanation of the drawing]

[0026] [Figure 1] The figure shows a chair according to an embodiment, where (A) is a perspective view seen from above and in front, (B) is a perspective view seen from below and behind with the back support device omitted, and (C) is a separated perspective view seen from above and behind. [Figure 2] (A) is a rear view, and (B) is a side view. [Figure 3] This is a front view of the separation. [Figure 4] This is a separated perspective view of the main part, seen from the front and above. [Figure 5] (A) is a separated perspective view of the main part seen from the front and below, and (B) is a separated perspective view of a part of the back support device seen from the rear and above. [Figure 6] (A) is a partial front view with the backrest omitted, (B) is a rear view of the back support device, and (C) is a perspective view of the pad unit from the rear and above. [Figure 7] This is a separate side view showing the relationship between the backrest, back support column, and back support device (the back support column is shown as a front view). [Figure 8] This is a longitudinal cross-sectional side view (the back support device is shown as a side view). [Figure 9] (A) is a separated perspective view of the pad unit 14, (B) is a perspective view of the pad unit set in the housing, (C) is a cross-sectional view of (A) from the CC viewing direction, (D) is a cross-sectional view of (A) from the DD viewing direction, and (E) is a side view of another example. [Figure 10] This is a perspective view showing an example of the separation structure of a pad unit. [Figure 11] This is a diagram showing another example. [Figure 12] Another example is shown in the figure. [Modes for carrying out the invention]

[0027] Next, embodiments of the present invention will be described based on the drawings. In the following, the terms front, back, left, and right will be used to specify directions, but these directions are specified as those viewed from a person who is normally seated. The front view direction is the direction opposite to the seated person.

[0028] (1) Overview of the chair This embodiment is applied to a reclining swivel chair commonly used in offices and other similar settings. As shown in Figures 1 and 2, the chair comprises, as its main components, a seat 1, a backrest 2, a back frame 3 to which the backrest 2 is attached, and a leg device 4 with casters. A back support device 5 is positioned behind the backrest 2. The backrest 2 is made of a resin plate that flexes and deforms like an elastomer, and numerous elongated rectangular cutouts are made in multiple rows and columns to facilitate flexing and backward bulging deformation.

[0029] For example, as shown in Figure 1, the base body 7 is fixed to the leg support column (gas cylinder) 6 located in the center of the leg assembly 4, and the back frame 3 is connected to the base body 7 via a joint arm 8 so as to be able to tilt backward. Therefore, the chair of this embodiment is a reclining chair in which the backrest 2 tilts backward against an elastic means.

[0030] The back frame 3 has vertically elongated back support columns 9 located in the middle of the left and right sides, horizontally rotatably mounted horizontally elongated upper supports 10 at the upper ends of the back support columns 9, and left and right lower supports 11 integrally provided at the lower ends of the back support columns 9. The left and right ends of the upper supports 10 and the tips of the lower supports 11 are free ends, and the corners of the backrest 2 are connected to the tips of the upper supports 10 and the tips of the lower supports 11. Therefore, the backrest 2 is attached to the back frame 3 in a four-point support configuration.

[0031] If the pressure applied by a seated person is unevenly distributed to either the right or left side of the backrest 2, the upper support 10 can rotate horizontally, causing the backrest 2 to twist and deform. Therefore, the backrest 2 twists and deforms in accordance with the user's body movements. The back support column 9 and the upper support 10 are made of synthetic resin. The back support column 9 and the lower support 11 have a complex structure with ribs and are covered from the rear by a cover.

[0032] As shown in Figure 1(C), the upper support 10 has a curved shape in plan view, indenting towards the front (and bulging towards the back), and the left and right ends of the backrest 2 are connected to its left and right ends. Therefore, there is a large space between the upper support 10 and the backrest 2. The existence of this space allows the upper end of the backrest 2 to stretch and deform backward due to the pressure (body pressure) of the seated person.

[0033] On the other hand, as clearly shown in Figure 1(C), for example, the lower support 11 is curved such that its upper and lower surfaces become higher towards the tip when viewed from the rear, and the lower surface formed by the lower surfaces of the left and right lower supports 11 and the lower surface of the back support 9 (i.e., the lower surface of the back frame 3) is also a curved surface that bulges downward. Therefore, the back frame 3 as a whole has a shape similar to an anchor.

[0034] The backrest 2 in this embodiment is a bare type made of resin plate, but various designs can be adopted. For example, a structure in which cushioning material is attached to the front (or both sides) of a synthetic resin back panel (back inner shell) and the entire front and back is covered with a bag-like outer material, or a structure in which mesh material is attached to a rectangular frame can also be adopted.

[0035] (2) Basic structure of the back support device of the main embodiment As shown in Figures 4 and 5, the back support device 5 includes a pad unit 14 that supports the seated person from behind, and a lifting mechanism for adjusting its height. The lifting mechanism includes a front holder 15 that overlaps the rear surface of the pad unit 14, a vertically elongated, strip-shaped rail member 16 positioned behind the front holder 15, a rear holder 17 that holds the rail member 16 which is integrally connected to the front holder 15, and a vertically elongated housing 18 that houses these members. The pad unit 14 is fixed to the rear holder 17 with four screws 19 on the top, bottom, left, and right.

[0036] As shown in Figures 4 and 5, a recess 20 is formed on the front surface of the back support column 9 into which the housing 18 fits snugly. A downward projection 21 is formed on the lower surface of the housing 18, while an engagement hole 22 is formed on the lower surface of the recess 20 of the back support column 9 into which the downward projection 21 fits. Furthermore, an engagement recess 23 that is recessed toward the front is formed on the rear surface of the upper end of the housing 18, while an engagement step 24 is formed in the recess 20 of the back support column 9 into which the engagement recess 23 overlaps. In addition, a head portion 16a in a backward-tilting position is formed on the upper end of the rail member 16, which fits into the engagement recess 23 of the housing 18, and the head portion 16a and the housing 18 are fastened together to the engagement step 24 of the back support column 9 with a single screw 28.

[0037] As shown in Figures 4 and 5, a roughly T-shaped locking projection 26, having left and right wing plates 25, is provided projecting backward from the lower end of the rail member 16, while a roughly T-shaped engagement groove 27 into which the locking projection 26 fits is formed at the bottom of the housing 18. Therefore, the lower end of the rail member 16 is held in place relative to the lower end of the housing 18 in a way that prevents displacement in any direction, front, back, left, or right.

[0038] As shown in Figures 4 and 5, the rear holder 17 is formed in a frame shape with a forward-facing opening, having left and right forward-facing side plates 17a and upper and lower forward-facing ribs. The front holder 15 is fitted inside the rear holder 17 and held in a position where it cannot shift up, down, left, or right. In this state, the front holder 15 and the rear holder 17 hold the rail member 16 so that it can move up and down.

[0039] As shown in Figure 5(B), a number of engaging protrusions 30 are formed on the back of the rear holder 17 in a vertical direction as part of the first height adjustment means. On the other hand, the rear holder 17 is configured to hold the rail member 16 from the front, and left and right locking claws 31 that engage and disengage with the engaging protrusions 30 are provided protruding inward to the left and right at the rear ends of the side plates 17a that sandwich the rail member 16 from the left and right. Therefore, the height of the pad unit 14 can be adjusted by engaging and disengaging the engaging protrusions 30 with the left and right locking claws 31.

[0040] Furthermore, in this embodiment, as part of the second height adjustment means, as shown in Figure 5(B), a pair of movable engagement protrusions 32 projecting backward are arranged vertically on the rear surface of the rear holder 17, while a multi-stage group of pairs of fixed engagement protrusions 33, with which the movable engagement protrusions 32 engage and disengage, is formed on the bottom surface of the housing 18. The movable engagement protrusions 32 of the rear holder 17 are arranged on both sides of a vertically elongated guide rib 34, and the guide rib 34 slides between the left and right fixed engagement protrusions 33. Note that either the first height adjustment means or the second height adjustment means may be formed alone.

[0041] (3) Pad Unit For example, as shown in Figures 4-6, the pad unit 14 comprises an upper pad 37 that supports the lower back of the sitter, a lower pad 38 that supports the sacrum of the sitter, and a base body 39 fixed to the rear holder 17 with screws 19. The base body 39 is generally plate-shaped and has mounting holes 40 through which the screws 19 used to fix it to the rear holder 17 pass.

[0042] The upper end of the base body 39 has knobs 41 protruding from both sides for the user to grasp when adjusting the height. The knobs 41 have a wedge shape, with the thickness decreasing towards the tip when viewed from the front. The base body 39 is slightly narrower in width than the width of the back support column 9, but the knobs 41 protrude outwards to the left and right of the back support column 9. Therefore, the user can easily grasp the knobs 41 with their hands behind them.

[0043] A forward-facing block section 39a is provided at the lower end of the base body 39, and the lower pad 38 rises from the forward-facing block section 39a. For example, as clearly shown in Figure 8, the lower pad 38 is inclined as a whole so that its height increases towards the front, and the front surface is curved in a forward-bulging manner when viewed from the side. Also, for example, as shown in Figure 6(A), the lower pad 38 has a shape that widens from top to bottom (narrows at the bottom) when viewed from the front, so that its width increases from left to right as it goes up, and it has a shape that is close to a heart shape when viewed from the front. The top is the widest, but the width from left to right is such that it only supports the sacrum of the seated person (i.e., it does not extend to the back of the ilium of the seated person).

[0044] For example, as shown in Figure 9(A), the upper pad 37 consists of a main body 37a positioned above the lower pad 38 to support the sitter from behind, and left and right foot portions 37b extending downward from both ends of the main body 37a, and is connected to the forward-facing block portions 39a of the base body 39 on both the left and right sides of the lower pad 38. Therefore, the upper pad 37 as a whole has a gate-like shape when viewed from the front, and there is a horizontally elongated gap 42 between the lower end of the main body 37a and the upper end of the lower pad 38.

[0045] The main body portion 37a and the foot portion 37b that constitute the upper pad 37 can be manufactured entirely from the same resin, or they can be made from different materials. The boundary position when they are made from different materials is illustrated by reference numeral 37e in Figure 9(A).

[0046] When the main body 37a and the foot portion 37b are made of different materials, the design can be improved by making their colors different. It is also possible to make the foot portion 37b colored and the main body portion 37a transparent or translucent, in which case the novelty is enhanced, further improving the design and increasing the product value. By making the foot portion 37b from a highly rigid material and the main body portion 37a from a highly elastic material, the overall strength can be ensured while facilitating the bending deformation of the main body portion 37a, thereby improving the comfort of the seated person. Combining differences in both mechanical properties and colors is even more beneficial.

[0047] When the main body 37a and the foot portion 37b are made of different materials, the means of joining them can include a method of integrally molding them by two-color molding or insert molding, a method of manufacturing them as separate components and then bonding them together, a method of forming a boss portion on one side and a cylindrical portion on the other side and then fitting them together, a method of manufacturing them as separate components and then fixing them with screws, or a method of manufacturing them as separate components and then welding them together by vibration welding or the like.

[0048] When the upper pad 37 is made of different materials, the position of the boundary 37e is not limited to the position shown in Figure 9(A), but can be set to any position. For example, the boundary 37e may be located on the main body 37a or the foot portion 37b. That is, for example, the upper half of the main body 37a may be made of a soft material (or a highly elastic material), and the lower half of the main body 37a and the foot portion 37b may be made of a hard material, or the lower half of the foot portion 37b may be made of a hard material, and the upper half of the foot portion 37b and the main body 37a may be made of a soft material (or a highly elastic material).

[0049] It is also possible to construct the lower part of the main body 37a and the foot portion 37b from a rigid material, and the majority of the main body 37a from a soft or highly elastic material. In any case, combining differences in color in accordance with differences in function is preferable as it improves the design. The upper pad 37 being made of different materials can also be applied to other embodiments and can also be applied to the lower pad 38.

[0050] For example, as clearly shown in Figures 6(A) and 6(B), in a front view, the foot portions 37b of the upper pad 37 are of equal width on both sides and conform to the left and right lateral edges of the foot portions 37b. Therefore, the left and right foot portions 37b are curved and inclined so that the distance between them narrows downwards (widens upwards), and in a front view, the lower ends (bases) of the foot portions 37b overlap with the back support 9. Consequently, in a back view of the chair, the bases of the foot portions 37b are hidden behind the back support 9.

[0051] Furthermore, as clearly shown in Figures 6(A) and 6(B), for example, the side edge of the main body portion 37a of the upper pad 37 is smoothly continuous with the outer edge of the foot portion 37b, and is slightly inclined to widen upwards while curving slightly outwards. In addition, the upper surface of the main body portion 37a is slightly curved upwards when viewed from the front, and the upper corners on the left and right are rounded.

[0052] For example, as clearly shown in Figures 4, 6(C), and 7, the foot portion 37b constituting the upper pad 37 decreases in width (thickness) from the base upwards, and the majority of the main body portion 37a is in the form of a thin plate. In addition, the upper pad 37 is curved in a forward-bulging shape when viewed from the side, with the connecting portion between the main body portion 37a and the foot portion 37b located at the very front (that is, the entire upper pad, including the main body portion and the foot portion, is curved in a forward-bulging shape when viewed from the side, so that the gap is at the very front). Because the main body portion 37a is in the form of a plate, it is allowed to bend backward due to the pressure (body pressure) of the person sitting on it.

[0053] For example, as shown in Figure 6(C), the left and right middle sections of the main body 37a that make up the upper pad 37 are recessed toward the rear. In other words, the left and right middle sections of the main body 37a are recessed relief grooves 43 that are recessed toward the rear. This is to prevent the seated person's lumbar spine from making contact with the pad.

[0054] (4) Elastic support means for body pressure For example, as can be seen from Figure 9, the upper pad 37 is rotatable backward using the lower ends of the left and right foot portions 37b as pivot points, and the lower ends of the left and right foot portions 37b are connected to the forward-facing block portion 39a of the base body 39 by damper pins 45.

[0055] The damper pin 45 has a movable cylinder 46 that penetrates the foot portion 37b of the upper pad 37 from the left and right directions, a fixed cylinder 47 that penetrates the forward-facing block portion 39a of the base body 39 from the left and right directions, and a central shaft 49 fixed to the movable cylinder 46 via a sleeve 48. The movable cylinder 46 is fixed to the foot portion 37b of the upper pad 37 with screws (not shown), and the fixed cylinder 47 is fixed to the forward-facing block portion 39a of the base body 39 with screws (not shown).

[0056] Multiple inward-facing pieces 50 are integrally formed on the inner surface of the fixed cylinder 47, arranged circumferentially apart. On the central axis 49, an outward-facing piece 51 is integrally provided, back-to-back with the inward-facing pieces 50, and a rubbery elastic body 52 is interposed between the inward-facing pieces 50 and the outward-facing piece 51. Therefore, when the upper pad 37 tilts backward, the central axis 49 and the outward-facing piece 51 rotate, compressing the elastic body 52. ​​In other words, when the backward pressing force (body pressure) of the seated person acts on the upper pad 37, the upper pad 37 tilts backward against the elasticity of the elastic body 52.

[0057] As illustrated in Figure 9(C), the upper pad 37 is set to hit the forward-facing block portion 39a of the base body 39 when it rotates by a certain angle. That is, as shown by the dashed line in Figure 8, the upper pad 37 is restricted from rotating any further once it has tilted backward to a certain extent, and when the seated person's body pressure is applied to the upper pad 37 while its backward tilt is restricted, the upper pad 37 is set to bend and deform backward against its own elasticity. It is also possible to use the compression deformation of the elastic body 52 as a means of restricting the backward tilt angle. That is, it is possible to restrict the backward tilt angle of the upper pad 37 by fully compressing the elastic body 52, and it is also possible to provide a stopper portion on the fixed cylinder 47 that the outward-facing piece 51 hits.

[0058] Therefore, when a seated person applies body pressure to the upper pad 37, a relatively light resistance can be applied to the lumbar region up to a certain point, and then a stronger resistance can be applied after the rotation of the upper pad 37 stops. This prevents a feeling of being constricted by the upper pad 37 while firmly supporting the lumbar region.

[0059] In another example shown in Figure 9(E), in a basic configuration in which the lower ends of the left and right foot portions 37b are connected to the forward-facing block portion 39a of the base body 39 by a pivot shaft 57, a bracket 53 is positioned straddling the upper surfaces of the left and right foot portions 37b, and this bracket 53 is fixed to the left and right foot portions 37b with screws 54. A compression coil spring 55 is positioned between the upright portion 53a provided in the middle of the left and right of the bracket 53 and the base body 39. Although not shown, the rotation range of the foot portions 37b is predetermined by front and rear stoppers. A spring receiver 56 can also be used as a stopper to restrict the backward tilting posture.

[0060] As a means of providing elastic resistance to the rearward tilting of the upper pad 37, in addition to rubber damper pins 45 and coil springs, rod-shaped torsion bars, leaf springs, and torsion coil type torsion springs can also be used. Oil-type rotary dampers can also be used.

[0061] In this embodiment, the upper pad 37 is tiltable backward and elastically deformable, while the lower pad 38 is set to elastically deform in response to the seater's body pressure. However, it is also possible to connect the lower pad 38 to the base body 39 so as to be able to tilt backward and tilt it backward against the elastic body, but in this case, it is preferable to set the elastic resistance to a value greater than the resistance to the upper pad 37.

[0062] The upper pad 37 (and lower pad 38) can also be configured to undergo only elastic deformation without tilting backward due to the seater's body pressure. In this case, the pad unit 14 can be made entirely of synthetic resin, but it can also be manufactured in multiple parts and joined together for ease of molding and improved functionality. An example of a pattern in which multiple parts are manufactured and then assembled is shown in Figure 10.

[0063] Specifically, in the example shown in (A) of Figure 10, the base body 39 and the upper pad 37 are molded as a single unit from, for example, polypropylene or polycarbonate, while the lower pad 38 is molded as a separate component from polypropylene or the like, and the lower pad 38 is fixed to the base body 39 by screws 58 running lengthwise. In this case, it is preferable that the lower pad 38 and the base body 39 interlock to increase the fixing strength. The single unit consisting of the base body 39 and the upper pad 37 can be easily molded using a mold (cavity and core) that moves relative to each other in the direction indicated by the arrow 59 in (A).

[0064] In the example shown in Figure 10(B), the base body 39 and the lower pad 38 are molded as a single unit, while the upper pad 37 is molded as a separate component. The foot portion 37b of the upper pad 37 is fixed to the base body 39 and the forward-facing block portion 39a with left and right long screws 60. The base end of the foot portion 37b is formed in a side-view angular shape to prevent rotation.

[0065] The base body 39 and the lower pad 38 can be manufactured inexpensively using a general-purpose resin such as PP, while the upper pad 37 can be manufactured using a resin material with excellent flexibility. This allows for the lowest possible cost while maintaining the functionality of each component. In either example, the integrated product consisting of the base body 39 and the lower pad 38 can be easily molded using a mold that moves relative to (A) in the direction indicated by the arrow 59.

[0066] In the example shown in Figure 10(C), the upper pad 37, the lower pad 38, and the base body 39 are manufactured as separate components, and the three are fixed together with screws 58 and 60 to form the pad unit 14. This example has the advantage of simplifying the mold structure.

[0067] (4) Summary As shown in Figures 7 and 8, the backrest 2 is gently curved in a forward-projecting shape in a longitudinal lateral view, based on an adult with a standard height of approximately 160-170 cm, so that the height of the third or fourth lumbar vertebra of the seated person is roughly at the furthest forward position. In a plan view, it is gently curved in a forward-concave shape, and the degree of curvature in the plan view decreases towards the top (it becomes flatter towards the top).

[0068] As shown in Figures 7 and 8, with the pad unit 14 positioned at approximately an intermediate height, the upper end of the lower pad 38 is set to be at approximately the same height as the front end of the backrest 2. In other words, if the sitter is an adult of standard height, the upper end of the lower pad 38 is set to be at approximately the same height as the upper end of the sitter's sacrum. Therefore, the main body 37a of the upper pad 37 is approximately at the height of the sitter's second to fifth lumbar vertebrae.

[0069] While the shape of the posterior surface of the lumbar region and pelvic region varies from person to person and is not uniform, when looking at the left-right middle section, the posterior surface from the sacrum to the lumbar spine is smoothly continuous. In this embodiment, the lower pad 38 has a width sufficient to support the sacrum, while the upper pad 37 has a width that primarily supports the area closer to the lumbar spine. Therefore, regardless of individual differences, the sacrum and lumbar spine can be firmly supported. Consequently, it offers excellent adaptability to differences in body size.

[0070] For example, when a seated person is performing tasks such as operating a PC, the posture of the pelvis and sacrum remains constant regardless of whether they are standing upright, leaning backward, or leaning forward, whereas the posture of the vertebrae (lumbar and thoracic vertebrae) changes significantly. Therefore, if the upper pad 37 is a rigid flat plate, when the upper body leans backward, the upper pad 37 may press against the waist and back, potentially causing discomfort to the seated person.

[0071] In contrast, in this embodiment, firstly, the main body portion 37a of the upper pad 37 can tilt backward and bend due to the pressure of the seated person's body, thus preventing strong pressure on the narrow area of ​​the lower back. To add further, since the backrest 2 in this embodiment is made of elastomer, it bends and deforms gently when supported from behind by the upper pad 37, so that the lower back is supported by the wide area of ​​the backrest 2 while the upper pad 37 bends and deforms.

[0072] Next, because the main body portion 37a of the upper pad 37 is gently curved so as to bulge forward in a side view, the backrest 2 maintains a gently curved state in a longitudinal side view. As a result, the person's lower back is supported over as wide an area as possible through the backrest 2, and in this respect as well, the sitter's lower back does not experience any upward thrusting.

[0073] Furthermore, in this embodiment, as described above, the main body portion 37a of the upper pad 37 is gently curved, but it slopes upward so as to move away from the backrest 2. As a result, the bracing phenomenon at the upper end of the main body portion 37a does not occur, and even when the sitter leans against the backrest 2, the backrest 2 can be gently curved, preventing the bracing phenomenon caused by the bending of the backrest 2. Therefore, even in a reclined state with the backrest 2 tilted backward, the sitter does not feel any bracing in the lower back and can enjoy a comfortable and relaxed state.

[0074] As mentioned earlier, the sacrum, lumbar vertebrae, and thoracic vertebrae are covered from behind by the erector spinae muscles, so the lumbar and thoracic vertebrae have high resistance to pressure from behind. However, the flanks lack support (bones) and have more fat, so they have low resistance to pressure from behind, and even weak pressure can cause pain or discomfort.

[0075] On the other hand, in this embodiment, the maximum width of the main body portion 37a of the upper pad 37 is about 10 to 15 centimeters, which is a width sufficient to support the erector spinae muscles, so the sitter does not feel any pressure and is comfortable. To add further, since the backrest 2 of this embodiment has some degree of lumbar support, the backrest 2 elastically deforms even in a plan view when supported by the main body portion 37a of the upper pad 37, so the backrest 2 deforms to fit the sitter's lumbar region, thereby ensuring a high level of comfort. The advantage of the relief groove portion 43 in the left and right middle portions of the main body portion 37a has already been described.

[0076] As in the embodiment, by providing a handle portion 41 on the base body 39, the distance between the handle portion 41 and the front holder 15 and rear holder 17 is small, allowing the pad unit 14 to be raised and lowered without twisting.

[0077] Figure 8 shows the upper pad 37 with its main body 37a in contact with the backrest 2. However, in a neutral position where the seated person's body is not in contact with the backrest 2, there may be a gap between the backrest 2 and the main body 37a (and the lower pad 38). In other words, the backrest 2 may be configured to deform slightly under body pressure before contacting the main body 37a (and the lower pad 38).

[0078] Regarding the relationship between the upper pad 37 and the lower pad 38, various configurations can be adopted, such as when the sitter is in a standard upright posture with their upper body upright, the lower pad 38 and upper pad 37 lightly touching the sitter; when the sitter is in a standard posture with their upper body upright, neither pad touches the sitter; or when only the lower pad 38 lightly touches the sitter. Since there are individual differences in how the upper pad 37 and lower pad 38 touch the sitter, with some people preferring a stronger touch and others not, it is also possible to make the front-to-back position of either the upper pad 37 or the lower pad 38, or both, adjustable.

[0079] (5) Variations and Others Figure 11 shows a modified example of the pad unit 14. In this embodiment, the lower pad 38 has approximately the same width from left to right throughout its entire height. On the other hand, the upper pad 37 has a single foot portion 37b located behind the lower pad 38, and the foot portion 37b is fixed to the forward-facing block portion 39a of the base body 39 by a screw 61 inserted from below.

[0080] In this modified example, the foot portion 37b deforms to bend backward against its elasticity. Consequently, the entire main body portion 37a of the upper pad 37 retracts against the elasticity of the foot portion 37b. It is also possible to configure the upper part of the foot portion 37b as a hinge portion that bends against elasticity, so that the main body portion 37a tilts backward with respect to the hinge portion.

[0081] In the example shown in Figure 12, the upper pad 37 has a main body 37a positioned above the lower pad 38 and a bracket plate 37d that is integrally connected to the upper end of the main body 37a and extends downward. The lower end of the bracket plate 37d is fixed to the base body 39 with screws, or it is connected via a support shaft so as to be able to tilt backward. In this example, the upper pad 37 may be moved backward by utilizing the elastic deformation of the bracket plate 37d, or the backward tilting and bending deformation of the bracket plate 37d may be used in combination.

[0082] In this embodiment, the bracket plate 37d of the upper pad 37 is positioned behind the lower pad 38, so it is also possible to extend the lower pad 38 to the left and right to support the iliac crest of the seated person.

[0083] The embodiments of the present invention have been described above, but the present invention can be implemented in various other ways. For example, the target chair is not limited to swivel chairs, but can also be applied to non-height adjustable chairs such as pipe chairs, fixed chairs such as theater chairs, or sofas. The backrest can also be of mesh type or cushion type.

[0084] The upper and lower pads can be formed to have the same width, or the lower pad can be made wider than the upper pad. In the latter case, the lower pad can be configured to extend in a continuous line from side to side, or to be separated into left and right sections to support the ilium. In this embodiment, the back support device is attached to the back support column, but the back support device can also be attached to other types of back frames to which the backrest is attached, or to a dedicated support column that rises up behind the seat. [Industrial applicability]

[0085] The present invention can be embodied in a chair equipped with a back support device. Therefore, it is industrially applicable. [Explanation of Symbols]

[0086] 1 seat 2 Backrest 3 Backframe 5. Back support device 9 Back strut 10 Upper Support 11 Lower Support 14 Pad Unit 15 Front Holder 16 Rail members 17 Rear Holder 18 Housing 20 recesses 37 Upper pad 37a Main body 37b Foot 38 Lower pad 39 Base 39a Forward-facing block section 41. Thumb part 42 gaps

Claims

1. A chair having a back support device positioned behind the backrest that can support the sitter at both the height of the pelvis and a height above it, The aforementioned back support device has a lower pad capable of supporting the sacrum or pelvis of the seated person, and an upper pad capable of supporting the seated person at the height of the vertebrae, with the left and right widths of the lower pad and the upper pad being different. chair.

2. The lower pad is formed to be narrower than the upper pad. The chair described in claim 1.

3. The width of the aforementioned lower pad is such that it supports only the sacrum of the seated person and does not extend to the ilium. The chair described in claim 2.

4. The upper pad has a main body that supports the seated person's body and left and right foot portions that extend downward from its left and right sides, and the lower pad is positioned between the left and right foot portions of the upper pad, with a gap between the main body of the upper pad and the lower pad. The chair according to claim 2 or 3.

5. The base end of the lower pad and the left and right foot portions of the upper pad are connected to a common base body, which is attached to the back support columns located in the left and right middle sections behind the backrest, either in a height-adjustable or non-height-adjustable manner. A chair as described in any one of claims 1 to 3.

6. The upper and lower pads, when viewed from the front, have a curved shape with their left and right side edges bulging outward, and their width narrows downward as they taper downwards. A chair as described in any one of claims 1 to 3.

7. The upper pad, including the main body and foot portion, is curved in a forward-bulging shape when viewed from the side, such that the gap is at the very front. The chair described in claim 4.

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