chair

Abstract

This invention discloses a back support device that offers superior support for the seated person. [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 sitter's sacrum (or pelvis), and a base body 39 to which the lower pad 37 is attached. The upper pad 37 has a main body 37a and left and right foot portions 37b, and the lower ends of the foot portions 37b are connected to the base body 39 so as to tilt backward against an elastic means. Furthermore, the upper pad 37 flexes and deforms under the pressure of the sitter's body. The lower pad 38 is positioned surrounded by the upper pad 37. The sacrum or pelvis of the person is firmly supported by the lower pad 38, while the lower back is softly supported by the rotatable upper pad 37.

Description

Technical Field

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

Background Art

[0002] In chairs with a backrest, many proposals have been made to provide a back support device that supports the waist and pelvis of a seated person from behind. In particular, for the driver's seat of an automobile, the back support device has also been devised so that the 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 constituting 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 and 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 kept 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 kept 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 kept 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] For example, when using a chair in an office, the user frequently changes their upper body posture, such as standing upright, leaning forward, or leaning backward. Therefore, it is necessary that the sacrum, pelvis, and lumbar spine are properly supported even when the upper body posture changes.

[0007] Therefore, considering Patent Document 1 from the perspective of an office chair, it can be said that in Patent Document 1, the lumbar support plate and pelvis support plate can only be changed in front-to-back position, and are not able to accurately support the pelvis and lumbar spine in accordance with changes in posture when the user changes the posture of their upper body.

[0008] The present invention was made against this backdrop, and in particular, with regard to office chairs, it aims to disclose a structure that can accurately support the back in accordance with changes in the user's posture. [Means for solving the problem]

[0009] 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 back support device is positioned behind the backrest to support the sitter, and the back support device has a lower pad that can support the sitter's sacrum or pelvis, and an upper pad that can support the sitter at the height of the vertebrae." In this basic configuration, "Only the upper pad moves against the elastic force due to the pressure applied by the seated person, Alternatively, both the upper and lower pads are set to move against the elastic force of the seated person's pressure, such that the amount of movement the upper pad can make is greater than the amount of movement the lower pad can make. This is the structure.

[0010] The invention of claim 2 is an extension of claim 1, "At least the upper pad is capable of tilting backward against the elastic means." This is the configuration. The elastic means include springs made of metal or rigid resin, or rubbery elastic bodies.

[0011] The invention of claim 3 is an extension of claim 2, "The upper pad is capable of bending and deforming to escape to the rearward side by the pressure applied by the seated person, while tilting backward against its elasticity." This is the structure.

[0012] The invention of claim 4 is an extension of claim 2 or 3, "The lower pad is permitted to flex and deform under the pressure of the seated person without tilting backward." This is the structure.

[0013] The invention of claim 5 is an extension of any of claims 1 to 3, "The aforementioned lower pad has a width that allows it to support only the sacrum of the seated person, The upper pad has a wider width than the lower pad. This is the structure.

[0014] The invention of claim 6 is also an example of any of claims 1 to 3, "The upper and lower pads are curved in a forward-bulging shape when viewed from the side." This is the structure.

[0015] The invention of claim 7 is also an example of any of claims 1 to 3. "The upper pad and the lower pad are provided on a common base body, and the base body is attached to the member that supports the backrest so as to be able to move up and down." This is the structure.

[0016] The invention of claim 8 is also an example of any of claims 1 to 3, "The lower pad is designed to have greater elastic resistance to the pressure applied by the seater than the upper pad." It is configured as such.

Advantages of the Invention

[0017] When a person is seated, the buttocks are resting on the seat surface, so the posture of the pelvis and the sacrum that make up the buttocks does not change much. However, the waist and the back continuous with it tilt significantly backward or forward. Therefore, the waist needs to be properly supported according to the degree of backward tilt. In addition, since individual differences such as differences in muscle mass are likely to occur in the waist, a function to absorb individual differences is also necessary. On the other hand, the back of the pelvis and sacrum is in a state where the skin is stretched over the bone and there are almost no individual differences such as differences in muscle mass. Also, since the height from the seat surface is low, the requirement for following the backward tilt when supporting is low. Rather, stability should be emphasized.

[0018] However, in the present invention, at least the upper pad retreats due to the pressing force (body pressure) of the seated person, so it can accurately support the waist following the backward movement of the upper body and can also absorb individual differences such as differences in muscle mass. On the other hand, since the lower pad does not retreat or retreats less than the upper pad, the pelvis and sacrum can be maintained in a stable posture.

[0019] Therefore, in the present invention, the pelvis and sacrum can be stably held to prevent or suppress the occurrence of low back pain and fatigue, and can support with high fitness without giving a feeling of tightness even when the upper body is tilted backward. Note that since the pressure resistance of the back of a person's torso is very high at the location of the pelvis and sacrum, even if the lower pad does not retreat or retreats less than the upper pad due to the body pressure of the seated person, it does not give a feeling of tightness to the location of the pelvis and sacrum and can stably support the pelvis and sacrum.

[0020] When the upper pad is tilted backward (rotated) as in claim 2, the body pressure of the seated person acts as a moment on the upper pad, so it can be ensured that the upper pad escapes and moves due to the body pressure. Therefore, the followability of the upper pad with respect to the backward movement of the seated person can be enhanced, and high fitness can be ensured.

[0021] The elastic resistance to the backward tilt of the upper pad can be arbitrarily set by adjusting the resistance of the elastic body. However, if the upper pad is configured to only tilt backward against the elastic body, larger individuals may perceive the resistance as low (the spring as too soft). Conversely, if the stiffness of the elastic body is adjusted to suit larger individuals, smaller individuals may perceive the spring as too stiff, potentially reducing the tolerance for differences in body size.

[0022] In contrast, as described in claim 3, when the upper pad is tilted backward and deformed by bending, if the person is large in build and exerts a lot of body pressure, elastic resistance can be provided by deforming the upper pad by bending after it has fully tilted backward. Therefore, even if the person is large in build, a feeling of tightness can be eliminated and a high level of fit can be provided.

[0023] Furthermore, there are two ways in which a seated person uses a chair with their upper body leaning backward: one is to work in a reclined posture with the backrest tilted backward while keeping the head upright to operate a computer on a desk (or look at a monitor), and the other is to adopt a relaxed posture with the head tilted back. With the configuration of claim 2, in the reclined working posture, the upper pad is tilted backward to provide stable support to the lower back, while in the relaxed posture, the upper pad is allowed to flex and deform in response to the curvature of the upper body to ensure a good fit to the body (eliminating any feeling of tension).

[0024] When a seated person leans their upper body backward, the pelvis and sacrum do not remain completely still, so it is possible to adopt a structure in which the lower pad tilts backward against a spring mechanism. However, since the backward tilting movement of the pelvis and sacrum is slight, adopting a configuration in which the lower pad moves out of the way due to flexural deformation, as in claim 4, allows for the necessary function to be ensured with a simple structure.

[0025] The sacrum is connected to the pelvis and vertebrae, but since the sacrum is located in the middle of the body and there are no individual differences in width, etc., adopting a configuration that supports only the sacrum with a lower pad as in claim 5 allows for stable support of the pelvis and sacrum regardless of individual differences, thereby eliminating strain on the lower back. On the other hand, because the upper pad is wide, the lower back can be supported softly without causing a feeling of tension.

[0026] As described in claim 6, by curving the lower and upper pads in a forward-bulging shape when viewed from the side, it is possible to prevent pressure on specific areas of the seated person's rear, and it is also excellent in accommodating changes in the seated person's posture and differences in body shape.

[0027] Claim 7 allows the lower and upper pads to be set to heights appropriate to the wearer's physique, thereby further improving the support function.

[0028] The pelvis and sacrum rarely tilt backward, and in fact, it is preferable to support them from behind to prevent excessive backward tilting. Furthermore, there are few pain-sensing nerves in the pelvis and sacrum area, and they have high compression resistance, so even if the elastic resistance to backward tilting is high, it will not cause discomfort to the sitter. Therefore, as in claim 8, by keeping the lower pad in a somewhat rigid state, the pelvis and sacrum can be stably supported without causing discomfort to the sitter, contributing to fatigue prevention and lower back pain prevention. [Brief explanation of the drawing]

[0029] [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]

[0030] 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.

[0031] (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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] (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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] (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.

[0045] 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.

[0046] 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).

[0047] 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.

[0048] 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).

[0049] 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.

[0050] 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.

[0051] 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).

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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 lumbar spine or vertebrae of the person sitting from coming into contact with the pad.

[0057] (4) Means for imparting elastic resistance 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.

[0058] 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).

[0059] 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.

[0060] As illustrated in Figure 9(C), the upper pad 37 is set to rotate by a certain angle so that the stopper 37c hits the forward-facing block portion 39a of the base body 39. In other words, 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. When the backward tilting of the upper pad 37 is restricted, and the seater's body pressure is applied to the upper pad 37, the upper pad 37 is set to bend and deform backward against its own elasticity (it deforms so that its upper end recedes).

[0061] 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.

[0062] As a means of restricting the backward tilt angle, it is also possible to utilize the compressive deformation of the elastic body 52 instead of the stopper 37c. That is, it is also possible to restrict the backward tilt angle of the upper pad 37 by fully compressing the elastic body 52. ​​Alternatively, it is also possible to provide a stopper portion on the fixed cylinder 47 that the outward-facing piece 51 contacts.

[0063] 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.

[0064] 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. Rotary dampers such as oil-type dampers can also be used.

[0065] 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.

[0066] 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.

[0067] 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).

[0068] 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.

[0069] 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.

[0070] 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.

[0071] (4) Summary When a person uses a chair, if the upper body is upright, the weight of the upper body acts directly on the pelvis and sacrum from above, so there is no strain on the pelvis, sacrum, or muscles, thus preventing fatigue and lower back pain. Therefore, regardless of the posture of the upper body, it is preferable that the sacrum and the first lumbar vertebra are connected in a straight position (it is preferable that the sacrum and the first lumbar vertebra are not flexed), and to achieve this, the pelvis and sacrum need to be held in a stable position without being tilted too far backward.

[0072] On the other hand, there are several ways in which the chair can be used, such as performing work like operating a PC with the upper body upright, performing work like operating a PC with the upper body leaning forward, performing work like operating a PC with the upper body leaning backward and reclining while keeping the head and shoulders upright, and performing work like operating a PC with the upper body leaning backward and reclining while tilting the head and shoulders backward (comfortable posture). In all of these cases, the sacrum is supported by the lower pad 38, which allows the pelvis and sacrum to be held in a stable posture.

[0073] On the other hand, when the upper body leans backward, the backrest 2 bulges and deforms backward, and backward body pressure acts on the upper pad 37 via the backrest 2. However, since the upper pad 37 tilts backward using its lower end as a pivot point, the upper pad 37 rotates to escape and supports the lower back via the backrest 2. Therefore, the upper pad 37 does not press against the sitter's lower back, and the user can enjoy a high level of fit.

[0074] If the upper pad 37 tilts too far back, it loses its function as lumbar support. In particular, when operating a PC with the head and shoulders raised while reclined, it is necessary to prevent the lower back from sinking too much. In this embodiment, since the tilt angle of the upper pad 37 is restricted, it is possible to prevent the lower back from sinking too much and to prevent strain on the connection between the sacrum and lumbar vertebrae. As a result, PC operation in a reclined position can be performed without fatigue or lower back pain.

[0075] On the other hand, when the user is in a relaxed position with their head and shoulders tilted backward, the upper pad 37 flexes and deforms to curve backward from its fully reclined position, as shown by the dotted line in Figure 8. This allows the user to enjoy a relaxed state without feeling any tension.

[0076] 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.

[0077] 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.

[0078] 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 tensioning phenomenon at the upper end of the main body portion 37a does not occur, and even when the seated person leans deeply against the backrest 2 in a relaxed position, the backrest 2 can be gently curved, preventing the tensioning phenomenon caused by the bending of the backrest 2. Therefore, a comfortable and relaxed state can be enjoyed.

[0079] 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.

[0080] 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 lumbar support, the backrest 2 is supported by the main body portion 37a of the upper pad 37 and elastically deforms even in a plan view, so the backrest 2 deforms to fit the sitter's lumbar region, thereby ensuring a high level of comfort. If the left and right middle portions of the main body portion 37a are relief grooves 43, it prevents the lumbar spine from being pressed hard, which is comfortable.

[0081] It is beneficial to prevent excessive posterior tilting of the human pelvis and sacrum and to maintain stable support. Furthermore, since both the sacrum and pelvis have high compression resistance, even with firm support, the person will not feel any discomfort or tightness. Therefore, the resistance of the lower pad 38 to posterior tilting of the sacrum is set to be greater than the resistance of the upper pad 37 to posterior tilting of the lumbar region.

[0082] 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.

[0083] 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).

[0084] 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.

[0085] (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.

[0086] 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.

[0087] 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.

[0088] In this example, since the bracket plate 37d is positioned behind the lower pad 38, it is also possible to extend the lower pad 38 in the lateral direction to support the sitter's iliac crest with the lower pad 38.

[0089] 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.

[0090] 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.

[0091] Although many configurations are disclosed in this embodiment, each configuration can be an independent invention separate from the claims. For example, a gate-shaped upper pad (lumbar pad), a lower pad that supports only the sacrum (pelvis support), the front-to-back arrangement of the back support, base body, and upper or lower pad, and a structure in which the lumbar pad or pelvis support rises from the lower end of the base body, forming an overall U-shape. [Industrial applicability]

[0092] The present invention can be embodied in a chair equipped with a back support device. Therefore, it is industrially applicable. [Explanation of Symbols]

[0093] 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 45 Damper pin that serves both as a link and an elastic resistance provider. 52 Elastic body

Claims

1. A chair is provided with a back support device positioned behind the backrest that can support the sitter, and the back support device has a lower pad that can support the sitter's sacrum or pelvis, and an upper pad that can support the sitter at the height of the vertebrae, Only the upper pad moves against the elastic force of the seated person's pressure, Alternatively, both the upper and lower pads are set to move away from the seated person's pressure, resisting elasticity, while the amount of movement the upper pad can move away from is greater than the amount of movement the lower pad can move away from. chair.

2. At least the upper pad is capable of tilting backward against the elastic means, The chair described in claim 1.

3. The aforementioned upper pad is capable of bending and deforming to escape to the rearward side due to the pressure applied by the seated person, while tilting backward against its elasticity. The chair described in claim 2.

4. The aforementioned lower pad is allowed to flex and deform under the pressure of the seated person without tilting backward. The chair according to claim 2 or 3.

5. The aforementioned lower pad has a width that allows it to support only the sacrum of the seated person, The upper pad has a wider width than the lower pad. A chair as described in any one of claims 1 to 3.

6. The upper and lower pads are curved in a forward-bulging shape when viewed from the side. A chair as described in any one of claims 1 to 3.

7. The upper and lower pads are provided on a common base body, and the base body is attached to the member that supports the backrest so as to be able to move up and down. A chair as described in any one of claims 1 to 3.

8. The lower pad is designed to have greater elastic resistance to the pressure applied by the seater than the upper pad. A chair as described in any one of claims 1 to 3.

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