Tiltable chair

Abstract

A tiltable chair includes a flexible seat body including an integrally formed seat back and seat surface supported on a seat frame disposed on upper parts of legs, and the seat back connected to a back frame allowing tilting rearwards, the position of the connection being in an area around the upper part of the pelvis of a person seated thereon. A guide rail having an arc-shaped groove is fixed to the seat frame, and guide members which engage and roll in the arc-shaped grooves are pivotably supported on a shaft bracket of the rear surface of the seat surface. The arc-shaped groove has a high center so that the seat surface undergoes curved motion forward and upward such that the ischium is positioned lower than the lower part of the knees when the seat back tilts rearwards.

Claims

1. A tiltable chair comprising: legs; a flexible seat body in which a seat back and a seat surface are integrally formed; a back frame connected to an upper part of the legs with a back connector to allow a back portion of the seat back to tilt rearward in a region around an upper-pelvis area of a user; the seat back and the back frame being connected to each other by connectors allowing that the seat back to be movable in a vertical direction; a seat frame fixed to the upper part of the legs; a seat surface movement mechanism configured for causing the seat surface to move forward and upward with respect to the seat frame according to the rearward tilt of the seat back; the seat surface movement mechanism comprising two guide rails having arc-shaped structure with high centers being positioned on right and left sides of an underside of the seat surface, and respective guide members engaging the guide rails; the seat surface movement mechanism thus causing smooth movement of the seat surface according to a movement of the user when seated and leaning against the seat back to cause the seat back to flex with respect to the seat surface and tilt rearward, such smooth movement of the seat surface being forward and upward along a curved line such that an angle of the seat surface gradually increases and an ischium of the user sinks below lower parts of the knees of the user when the seat back tilts rearward; wherein the engagement of the guide rails with the guide members creates the curved line as a trochoid curve between a position of the seat surface when the seat back is upright and a most forward position of the seat surface, with the seat body being positioned inside a circle of a virtual arc and the virtual arc rolling for a predetermined angle on a horizontal of the seat surface; wherein the legs include pipe-shaped front legs and pipe-shaped rear legs and the seat frame comprises a front frame connecting the pipe-shaped front legs and a rear frame connecting the front frame with the pipe-shaped rear legs, the front frame including a sliding receiver, and a sliding member, configured for guiding a front portion of the seat surface, fixed to the seat surface.

2. The tiltable chair of claim 1, wherein the back frame includes integral armrests surrounding the seat surface to the left and right at a predetermined height.

3. The tiltable chair of claim 1, wherein the guide rails are configured as arc-shaped pipes and the guide members engage outer surfaces of the pipes.

4. The tiltable chair of claim 1, wherein the sliding receiver is made of synthetic resin, and the sliding member is fixed to an underside of the front portion of the seat surface.

5. The tiltable chair of claim 1, wherein the connectors connecting the back frame and the seat back include a first connector fixed to the back frame and a second connector fixed to the seat back with one of the connectors comprising a vertical arc groove and the other connector comprising a pin engaging the vertical arc groove.

6. The tiltable chair of claim 1, wherein the arc-shaped structures of the guide rails are grooves.

7. A tiltable chair comprising: legs; a flexible seat body in which a seat back and a seat surface are integrally formed; a back frame connected to an upper part of the legs and comprising a tilting device to allow a back portion of the seat back to tilt rearward in a region around an upper-pelvis area of a user; the seat back and the back frame being connected to each other by connectors allowing that the seat back is movable in a vertical direction; a seat frame fixed to the upper part of the legs; a seat surface movement mechanism configured for causing the seat surface to move forward and upward with respect to the seat frame according to the rearward tilt of the seat back; the seat surface movement mechanism comprising two guide rails having arc-shaped structure with low centers connected to the seat frame, and respective guide members connected to the seat body on right and left sides of an underside of the seat surface and engaging the guide rails; the seat surface movement mechanism thus causing smooth movement of the seat surface according to a movement of the user when seated and leaning against the seat back to cause the seat back to flex with respect to the seat surface and tilt rearward, such smooth movement of the seat surface being forward and upward along a curved line such that an angle of the seat surface gradually increases and an ischium of the user sinks below lower parts of the knees of the user when the seat back tilts rearward; wherein the engagement of the guide rails with the guide members creates the curved line as a trochoid curve between a position of the seat surface when the seat back is upright and a most forward position of the seat surface, with the seat body being positioned inside a circle of a virtual arc and the virtual arc rolling for a predetermined angle on a horizontal of the seat surface; wherein the legs include pipe-shaped front legs and pipe-shaped rear legs and the seat frame comprises a front frame connecting the pipe-shaped front legs and a rear frame connecting the front frame with the pipe-shaped rear legs, the front frame including a sliding receiver, and a sliding member, configured for guiding a front portion of the seat surface, fixed to the seat surface.

8. The tiltable chair of claim 7, wherein the back frame includes integral armrests surrounding the seat surface to the left and right at a predetermined height.

9. The tiltable chair of claim 7, wherein the guide rails are configured as arc-shaped pipes and the guide members engage outer surfaces of the pipes.

10. The tiltable chair of claim 7, wherein the sliding receiver is made of synthetic resin, and the sliding member is fixed to an underside of the front portion of the seat surface.

11. The tiltable chair of claim 7, wherein the connectors connecting the back frame and the seat back include a first connector fixed to the back frame and a second connector fixed to the seat back with one of the connectors comprising a vertical arc groove and the other connector comprising a pin engaging the vertical arc groove.

12. The tiltable chair of claim 7, wherein the arc-shaped structures of the guide rails are grooves.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 (a) is a side view showing the tilt chair embodied as a chair used in an office, and (b) is a perspective view of (a) from the back.

(2) FIG. 2 shows an office chair in an embodiment wherein (a) is a side view and (b) is a perspective view from the back.

(3) FIG. 3 is an exploded perspective view of components of the tiltable chair of FIG. 2.

(4) FIG. 4 is a perspective view showing a means for connecting a seat back with a back frame, wherein (a) shows an embodiment with an arc groove provided to a connector 22 of a back frame 3, and (b) shows a vertical, arc-shaped groove provided to a connector 1c of a seat back.

(5) FIG. 5 is a perspective view showing other embodiments of a connector for the seat back, wherein (a) shows a seat back connected to a back frame via an elastic body and (b) shows a seat back connected to a back frame via a spherical bearing.

(6) FIG. 6 shows an embodiment of the invention wherein (a) is an entire side view and (b) shows a cross-section A-A of (a).

(7) FIG. 7 is an exploded perspective view of components of the tiltable chair of FIG. 6.

(8) FIG. 8 is a side view showing an embodiment of the invention.

(9) FIG. 9 is an exploded perspective view of components of the tiltable chair of FIG. 8.

(10) FIG. 10 is a perspective view of a seat body fixed to the rear portion of a seat surface.

(11) FIG. 11 (a) is a side view of a tiltable chair using a seat body connected close to the lower end of a seat back and (b) is a rear view.

(12) FIG. 12 is a perspective view showing a chair, wherein the same piece is used for the seat body and back frame, and various legs are used. (a) shows a cantilever, (b) shows a reverse cantilever, (c) shows a cantilevered load caster, and (d) shows a so-called four-legged highchair.

(13) FIG. 13 is a perspective view showing an embodiment in which various legs equipped with center pillars are attached, wherein (a) shows a five-legged caster, (b) shows a five-legged highchair, and (c) shows a so-called four-legged type.

(14) FIG. 14 is an explanatory diagram for determining the movement trajectory of a seat surface.

(15) FIG. 15 is an enlarged view of the seat surface of FIG. 14.

(16) FIG. 16 is a side view of a chair equipped with an existing synchro-swinging mechanism.

EMBODIMENTS OF THE INVENTION

(17) An embodiment of the tiltable chair of the present invention is described with the example of an office chair having armrests.

(18) FIG. 2(a) is a side view of the tiltable chair, (b) is a perspective view seen from the back side, and FIG. 3 is an exploded perspective view of the components of that configuration.

(19) In this chair a back frame 3 is attached to the upper parts of four legs 5 that do not vertically expand or contract, a seat frame is attached to the upper parts of the legs 5. A seat body 1 in which a seat back 1b and a seat surface 1a are of one piece is assembled thereupon by means of a tilting device 10. In addition, in FIGS. 3, 2a and 2b are cushions.

(20) The back frame 3 is formed integrally with an armrest 3d, and is positioned on the back surface of the seat back 1b at about upper-pelvis height (here, it is set to about 19 cm from the seat surface), and at the right and left of the seat surface 1a at a prescribed height above the seat surface (here, about 22 cm).

(21) The seat frame 4 comprises a front frame 4a connected to the upper parts of coupled, pipe-shaped front legs 5, and a rear frame 4b that connects the front frame 4a and each of the back legs.

(22) The tilting device 10 is configured with a seat back connection means 10a and a seat-surface movement means 10b. Here, a seat body 1 made of one piece with a flexible synthetic resin is used. Further, the seat back 1b is formed, as shown in FIG. 2(a) in a side perspective, with a form that bulges in the downward and rearward directions from the point of connection with the back frame 3.

(23) As shown in FIG. 4(a), the seat back connection means 10a comprises connectors 22 which are fixed to the right and left of the back frame 3 and positioned in an area near the upper part of the pelvis on the back side of the seat back 1b, and are connected to connectors 1c that are fixed to the back surface of the seat back 1b.

(24) The connectors 1c of the seat back 1b provide a pin 6, and the connectors 22 of the back frame 3 comprise a vertical arc groove 22a. When the seat back 1b tilts, the pin 6 is able to move inside the vertical, arc-shaped groove 22 so that the seat back 1b tilts back smoothly. There is an opening in the lower part of this vertical arc groove 22a, and during assembly, the pin 6 of the connector 1c can simply be fitted to the lower part of the arc groove 22a while the seat back 1b of the seat body 1 is held.

(25) The seat-surface movement means 10b, as shown in FIGS. 2(a) and 3, has one guide rail 11 to the right and one to the left, with two arc-shaped grooves 11a formed in the front-to-back direction in the seat frame 4b. Guide members 12a, supported by shaft brackets 12 fixed to the underside of the seat surface 1a are engaging the curved grooves 11a in a pivotable manner. The arc-shaped grooves 11a are formed with having a high center.

(26) The shape of the arc-shaped groove 11a determines and creates a trajectory for the seat surface 1a to smoothly move forward and upward about 40 mm in the process of the seat back 1b tilting rearward 30 degrees, using the pin 6 of the connection means 10a as a fulcrum. Here, the arc-shaped groove 11a determines a trajectory (trochoid curve) which is the center line of the arc-shaped groove and is drawn by the starting point of a guide member 12a that is fitted into the arc-shaped groove when the seat body is positioned close to the periphery of a circle with a radius of 3000 mm, and the arc rolls for a prescribed distance over the horizontal surface of the upper surface.

(27) In addition, sliding receivers 13 are fixed to the front frame 4a of the seat frame 4, and a sliding member 14 is fixed near the front portion of the underside of the seat surface 1a. The sliding receivers 13 provide a synthetic resin wound in a semicircle around the frame 4a made of steel tubing. The shape of the lower end of the sliding member 14, like the above-described arc-shaped groove 11a, is determined by a trajectory (trochoid curve) traced by the point of contact between the sliding member 14 and the sliding receivers 13 when the seat body is placed close to the periphery of the circle of a virtual arc (e.g., 3000 R), and this arc rolls with a prescribed angle over the top surface.

(28) Further, one end of a return member 15 (here, a return spring is used) is locked to the seat frame 4 such that the reclined seat back 1b returns smoothly, and the other end is locked to the underside of the seat surface 1a. An addition, in FIG. 3, 16 is a cover provided.

(29) Because it is configured in this manner, the seat body 1 is in the rearmost position due to the return member 15, and the seat back 1b is more or less perpendicular when a seated person is not leaning back on the seat back.

(30) When a seated person leans back on the seat back, the pin 6 in the connector 1c of the seat back 1b engages with the arc groove 22a of the connector 22 of the back frame 3 and, using this as a fulcrum, the upper side tilts rearward from the back frame 3 of the seat back 1b. As this happens the curved portion of the seat back 1b, between the connection point (connector 1c) and the seat surface 1a, bends, and the seat surface 1a moves forward and upward, guided by the guide rail 11. Thus, the chair enters a reclining state.

(31) FIG. 2(a) shows the state of movement of the seat body 1 when the seat back 1b of the tilt chair tilts rearward. Straight lines indicate a state in which the seat back is upright, and dotted lines indicate a state in which the chair is at maximum tilted rearwards. The weight of the seated person becomes the reaction force for the rearward tilt of the seat back, so almost no difference in sitting comfort is experienced due to differences in weight.

(32) Next, different embodiments of the connecting means 10a for the seat back are explained with reference to FIG. 4(b).

(33) Here, the connecting means is used for the backrest 1b and provide a connector 3a fixed to the left and right sides of the back frame 3 on the back of the seat back 1b and being coupled to the connector 1c by a pin 6. The connector 1c is fixed to the back surface of the seat back 1b. A vertical arc groove 1d is formed in the connector 1c and, because the pin 6 is able to move inside the vertical arc groove 1d when the seat back 1b tilts rearward, the seat back 1b tilts rearward smoothly. The function of the connection means 10a is the same as in the case of FIG. 4(a).

(34) A different embodiment of the seat back connection means 10a is explained with reference to FIGS. 5(a) and 5(b).

(35) In FIG. 5(a), the connection means 10a provides a connector 24 on the back frame 3, with a pin 25 and an elastic rubber body 24b melted or glued between the pin 25 and an outer tube 24a. The pin 25 is fixed to a connector 23 on the seat back 1b. The point of connection can be only at the center of the back frame 3 in the right-left direction, or the connection can also be provided to the left and right of the seat back, as above. The connector 23 is formed with a pinhole 23a that opens in the horizontal direction, and fits to the pin 25 with having flat upper and lower surfaces, the pin 25 being secured by a screw. Because it is configured in this way, the upper part of the seat back 1b tilts rearward when the seat back 1b is leaned upon and the elastic body 24b deforms. The ability of the elastic body 24b to return to shape helps it to return with a light movement.

(36) The seat back connection means 10a in FIG. 5(b) connects the seat back 1b to the back frame 3 by way of a spherical bearing 27. The shaft part of a mounting member 26 fixed to the seat back 1b fits into the spherical bearing 27 and is secured with a retaining pin 29, and this fits into a mounting part 28 provided to the back frame 3, with the outer ring of the spherical bearing 27 secured by a pin 28a.

(37) There can be a point of connection only at the center between left and right of the back frame 3 or, as with the above seat back 1b, points of connection can be provided to the left and right of the seat back 1b. If a seated person turns to look behind or does a spinal stretch, etc., the seat back follows the movement according to the flexibility of the spherical bearing 27 and the seat back 1b.

(38) Next, a different embodiment of the seat-surface movement means 10b is explained with reference to FIGS. 6 and 7.

(39) In the seat-surface movement means 10b shown in FIG. 6(a), one pipe-shaped guide rail 17 (in this example also serving as a rear frame 4b) is fixed to the right side and one is fixed to the left side, and a guide member 17b sectioned into two pieces, upper and lower, engages in a slidable manner with the outside of the guide rail 17. The guide member 17b is connected by a pin 17c to a shaft bracket 17a fixed to the underside of the seat surface 1a.

(40) Here, the guide rail 17 is formed in a curve such that the trajectory on which the pin 17c moves is the trochoid curve mentioned above. The pin 17c is connected in such a way that it can freely pivot. With this device, as with the movement means 10b of the seat surface of the above embodiment, when the seat back 1b tilts rearward, the seat surface 1a moves under the guidance of the guide rail 17.

(41) Another embodiment of the seat-surface movement means 10b is explained based on FIGS. 8 and 9. This is similar to the above embodiment (FIG. 2, 3) with the difference that a guide rail 18 is fixed to the underside of the seat surface 1a, and a guide member 19a for engaging with and rolling in an arc-shaped groove 18a is supported by a shaft 19 fixed to a seat frame 4. In this case, the guide rail 18 moves with the rearward tilt of the seat back. Here, the arc-shaped groove 18a is formed with a low center, unlike the above case.

(42) If a seat body becomes one piece by connecting separate members, it can be manufactured by a small-scale manufacturing facility. An embodiment of this case is explained with reference to FIGS. 10 and 11.

(43) FIG. 10 shows the seat connections from slightly behind and from the side of a seat surface 1a. A projecting part 1h is formed at the rear part of the seat surface 1 the area of a joint 1g, and is attached to the forward part 1a of the seat surface 1 by fitting into the recessed part formed thereon. A rib 1j having flexibility is formed on the underside of the seat surface 1a.

(44) Further, in FIG. 11, below the connector that connects the seat back 1b with the back frame 3, connections are made with a connecting member 1e formed e.g. by elastic rubber. Because it is configured in this way, when the seat back 1b is leaned upon it bends more at the connecting member 1e. For this reason, a material that is somewhat lacking in flexibility can be used for the seat body.

(45) Next, an embodiment of a chair having various leg types, in which the seat body and back frame are one piece is explained with reference to FIGS. 12 and 13.

(46) In the above explanations of embodiments, the configuration had four legs that could not raise or lower or rotate the seat surface, but it is possible to install various types of legs. Here, the back frame 3 is the same for various types of legs 5.

(47) FIG. 12(a) shows what is called a cantilever type in which the front legs bend rearwards at the lower end, where the seat frame 4 is fixed to the top parts of legs 5a, and the back frame 3 is connected to the top parts of legs 5a. Further, FIG. 12(b) shows what could be called a reverse cantilever in which the rear legs bend forward at the lower end, and the upper end of a leg 5b connects to the back frame 3. In FIG. 12(c) caster wheels are provided to the legs 5b of 12(b) configured such that luggage can be placed on the leg surface.

(48) In addition, in FIG. 12(d) the four legs 5 shown in FIG. 2(a), (b) extend to adapt to a high desk or table.

(49) In FIG. 13 a seat surface 1a can be raised or lowered and rotated.

(50) FIG. 13(a) shows a five-legged chair with caster wheels, with a seat frame 4 being fixed to an upper part of a center pillar comprising the five legs 5e having caster wheels thereon. Further, FIG. 13(b) shows what might be called a five-legged highchair, with the center pillar of FIG. 13(a) extended, and a leg rest 5f provided thereto. FIG. 13(c) shows what can be called a four-legged type, equipped with four legs 5g not provided with caster wheels.

(51) The tilt chair of the present invention can, of course, be used not only as an office chair but anywhere, such as in meeting rooms or conferences.

(52) While the above embodiments of the present invention are described with specific measurements, this is for ease of understanding the invention, and the invention is not limited thereto.

LIST OF REFERENCE SIGNS

(53) 1 Seat body 1a Seat surface 1b Seat back 1c Connector 1d Vertical arc groove 1e Connecting member 1g Joint 1h Projecting part 1j Rib 2a Cushion 2b Cushion 3 Back frame 3a Connector 3b Pin hole 3d Armrest 4 Seat frame 4a Forward frame 4b Rear frame 5, 5a-5g Legs 6 Pin 10 Tilt device 10a Connection means of seat back 10b Movement means of seat surface 11 Guide rail 11a Arc-shaped groove 12 Shaft bracket 12a Guide member 13 Sliding receiver 14 Sliding member 15 Tension spring 16 Cover 17 Guide rail 17a Shaft bracket 17b Guide member 17c Pin 18 Guide rail 18a Arc-shaped groove 19 Shaft 19a Guide member 22 Connector 22a Arc groove 23 Connector 23a Pin hole 24 Connector 24a Outer tube 24b Elastic body 25 Pin 26 Mounting member 27 Spherical bearing 28 Mounting part 28a Pin 29 Retaining pin 31 Leg 32 Base 33 Seat back 34 Back support body 35 Seat 36 Seat support body 37 First swing center axis 38 Second swing center axis 39 Third swing center axis 40 Slide mechanism