Patent Description:
The present invention relates to a chair that is suitably utilized in an office or the like and in which a seat is movable in front-rear, left-right, and diagonal directions.

<CIT> discloses a chair having the features of the preamble of claim <NUM>.

<CIT> discloses a chair having a seat on a vertical post. The seat comprises an upper plate. On the upper side of the vertical post a lower plate is provided opposite to the upper plate. Between the upper plate of the seat and the lower plate elastic bodies are provided. The upper plate of the seat can incline relative to the lower plate on a protrusion.

<CIT> discloses a stool having a platform and a seat surface supported by a ball on the platform. The ball is moveable along the platform. On the ball, the seat surface can tilt with respect to the platform. A collar connects the seat surface and the platform. Said collar is elastic.

Further examples of chairs having a seat that is movable in front-rear, left-right, and diagonal directions include the chairs described in Japanese Unexamined Patent Application Publication <CIT> and Japanese Unexamined Patent Application Publication <CIT> (hereinafter referred to as Patent Documents <NUM> and <NUM>).

Patent Document <NUM> describes a configuration in which a plurality of fluid bags are connected by a flow path and a seat is tilted when air moves.

Patent Document <NUM> describes a configuration in which a plurality of independent air cushions are covered with a cover member and fitted into a recess of a seat to provide a cushioning property to a person sitting in the chair.

In the configurations of Patent Documents <NUM> and <NUM>, the seat can move freely by the cushioning effect. However, the degree of freedom of deformation of the seat is too high for a seated person to hold his or her posture on the seat, and therefore, the seated person needs to follow a movement of the seat rather than the seat following a movement of the seated person. As a result, the conventional seats are not designed suitably for supporting a movement of the seated person continuously changing his or her posture while the seated person balances his or her load.

To solve such a problem, a configuration is conceivable in which an upper base unit that receives a load of the seated person move in a direction of <NUM> degrees along a predetermined trajectory via a movement mechanism with respect to a lower base unit that supports the upper base unit, and a seat is attached to the upper base unit.

However, when only such a movement mechanism is employed, the movement can be regular to a certain degree, but the degree of freedom of the seat is still too high. Thus, when a user changes his or her posture, the user has to support his or her own weight during moving, so that a burden to the user may be high.

The present invention has been accomplished in view of such a problem, and an object thereof is to realize an unprecedented chair which has a simple structure and in which a seat can follow a free movement of a seated person in front-rear, left-right, and diagonal directions, a burden from an operation by which the seated person balances his or her load can also be reduced, and a movement by which the seated person changes his or her posture stably and continuously can be suitably supported.

The above object is solved by a chair having the features of claim <NUM>. Further developments are subject matter of the further claims.

That is, a chair of claim <NUM> includes a movement mechanism that causes an upper base unit to swing in a direction of <NUM> degrees with respect to a lower base unit, and a seat attached to the upper base unit. The chair further includes a damper mechanism as a mechanism separate from the movement mechanism, at a position connecting the upper base unit and the lower base unit, and the damper mechanism operates by following a movement in a direction of <NUM> degrees.

According to such a configuration, the upper base unit can follow a free movement of a seated person in front-rear, left-right, and diagonal directions by the movement mechanism, and the seated person can easily find a weight balance while supporting his or her own weight, and can change his or her posture stably and continuously. In particular, instead of imparting resistance to the movement mechanism, the damper mechanism is provided as a mechanism separate from the movement mechanism, and thus, it is possible to adjust a working condition of the damper mechanism, without changing the basic performance of the movement mechanism.

In an example of a specific embodiment of the movement mechanism, the movement mechanism includes a rolling surface that is curved and provided in at least one of surfaces of the upper base unit and the lower base unit that face each other, and when the upper base unit rolls with respect to the lower base unit, the seat provided in the upper base unit swings.

Such a damper mechanism is especially suitable when applied to a chair that causes the upper base unit to tilt downward in a movement direction of the seat, as the seat moves away from a reference position, regardless of which direction of <NUM> degrees the seat moves in from the reference position.

To increase the degree of freedom in design and achieve an appropriate damper effect, it is desirable that the damper mechanism is arranged at a plurality of locations around a predetermined center of the seat, and operates in at least one direction or both directions of an operation of expanding or contracting a distance between the upper base unit and the lower base unit.

To obtain a damper mechanism that appropriately responds to the free movement of the seat, it is desirable that the damper mechanism is provided between the upper base unit and the lower base unit and connected by a non-directional joint to at least one of the upper base unit and the lower base unit.

To achieve a uniform and easily adjustable damper effect, according to the invention, the damper mechanism includes a hole unit provided in one of the upper base unit and the lower base unit, a columnar member provided in the other one of the upper base unit and the lower base unit and inserted into the hole unit, and a friction material arranged between the hole unit and the columnar member.

To ensure a stable operation, it is desirable that a relative movement of the damper mechanism is a sliding motion of the hole unit and the friction material along a longitudinal direction of the columnar member.

An example of an embodiment preferred in relation to the damper mechanism includes a configuration in which an elastic member being elastically deformable is provided between the upper base unit and the lower base unit, and the upper base unit moves while compressing the elastic member between the upper base unit and the lower base unit.

Another embodiment preferred in relation to the damper mechanism includes a configuration in which a return spring that returns the seat to a predetermined reference position is interposed between the upper base unit and the lower base unit.

The present invention has the configuration described above, and thus, it is possible to provide a novel, useful chair designed to follow a free movement of a seated person in front-rear, left-right, and diagonal directions, and to appropriately support a movement of the seated person continuously changing his or her posture while balancing his or her load.

<FIG> illustrate an outer appearance of a chair according to the embodiment, and <FIG> and <FIG> illustrate views in which a part of a seat <NUM> is omitted. As illustrated in the drawings, in the chair, a movement mechanism <NUM> is provided as a movable support between the seat <NUM> and a leg <NUM>, a back <NUM> is attached to move integrally with the seat <NUM>, and arms <NUM> are attached not to move integrally with the seat <NUM> and the back <NUM>. <FIG> and <FIG> illustrate a state where the seat <NUM> is moved in a front-rear direction, and <FIG> illustrates a state where the seat <NUM> is moved in a left-right direction.

In the seat <NUM>, a circumference of a seat main body <NUM> is covered with upholstery <NUM>, and the seat <NUM> is attached to the movement mechanism <NUM> via a seat shell <NUM>. The seat shell <NUM> includes an inner seat shell <NUM> attached to a bottom surface of the seat main body <NUM> and an outer seat shell <NUM> that backs up the inner seat shell <NUM> and secures the connection to the movement mechanism <NUM>.

The leg <NUM> includes casters <NUM> at a lower end of a leg vane <NUM>, and a leg support post <NUM> erected from a center portion of the leg vane <NUM>, and the seat <NUM> is rotatably attached to an upper end side of the leg support post <NUM>. The leg support post <NUM> can be extended and contracted by a gas spring mechanism GS illustrated in <FIG> incorporated therein. In <FIG>, a reference numeral <NUM> indicates an operation lever for operating an operated unit 23a of the gas spring mechanism GS.

As illustrated in <FIG>, in the movement mechanism <NUM>, an upper base unit <NUM> and a lower base unit <NUM> are arranged to face each other, the lower base unit <NUM> is attached to the leg support post <NUM>, and the seat <NUM> is attached to the upper base unit <NUM>. An elastic member <NUM> is interposed between the upper base unit <NUM> and the lower base unit <NUM>. The periphery of the elastic member <NUM> is covered with a cover member <NUM>, as illustrated in <FIG>, <FIG>, <FIG>, and <FIG>, but the cover member <NUM> is omitted in the other drawings. Further, in <FIG>, <FIG>, and the like, the elastic member <NUM> is omitted.

The movement mechanism <NUM> supports the upper base unit <NUM> movably with respect to the lower base unit <NUM>, in the front-rear direction as illustrated in <FIG>, and in the left-right direction as illustrated in <FIG> and <FIG>, and further in directions of <NUM> degrees including these directions.

As illustrated in <FIG>, the upper base unit <NUM> includes a disk-shaped seat receiver <NUM> and a disk-shaped upper base plate <NUM> attached under the seat receiver <NUM>. The seat receiver <NUM> illustrated in <FIG>, and the like is illustrated as a single body, but the seat receiver <NUM> is actually integrally formed of a resin together with the outer seat shell <NUM> in the periphery thereof, as illustrated in <FIG> and the like. The upper base plate <NUM> is provided with high nuts <NUM>, and the seat receiver <NUM> is provided with boss holes <NUM> at positions corresponding to the high nuts <NUM>. In a state where a bottom surface of the seat receiver <NUM> abuts against a top surface of the high nuts <NUM>, the upper base plate <NUM> and the seat receiver <NUM> are coupled by bolts (not illustrated) inserted through the seat receiver <NUM> and the high nuts <NUM> from above.

As illustrated in <FIG>, the lower base unit <NUM> includes a disk-shaped support base unit <NUM> attached to the upper end of the leg support post <NUM> and a disk-shaped lower base plate <NUM> attached on the support base unit <NUM>. In <FIG>, reference numeral 322y indicates an engaging claw provided in the lower base plate <NUM>, and the engaging claw 322y engages with a peripheral edge portion of the support base unit <NUM> so that the lower base plate <NUM> and the support base unit <NUM> are integrated. As illustrated in <FIG> and <FIG>, a leg mounting unit 321a into which the leg support post <NUM> is fitted is provided in a bottom surface of the support base unit <NUM>, and the leg mounting unit 321a is reinforced by ribs 321b extending in a radial direction to increase the rigidity of the leg mounting unit 321a. The operated unit 23a used to operate a gas spring is provided at the upper end of the leg support post <NUM> and in a state where the leg support post <NUM> is inserted into the leg mounting unit 321a, the operated unit 23a is arranged at a position where the operated unit 23a can be operated by an operation unit <NUM>.

<FIG> is a schematic view of rolling surfaces constituting the movement mechanism <NUM>, in which the elastic member <NUM> is omitted. As illustrated in <FIG>, surfaces of the upper base unit <NUM> and the lower base unit <NUM> that face each other (in the present embodiment, a facing surface 312a of the upper base plate <NUM> constituting the upper base unit <NUM> and a facing surface 322a of the lower base plate <NUM> constituting the lower base unit <NUM>) form rolling surfaces that roll with respect to each other. In the present embodiment, the rolling surface 322a of the lower base plate <NUM> is composed of a flat surface, the rolling surface 312a of the upper base plate <NUM> is composed of a curved surface that bulges toward the rolling surface 322a of the lower base plate <NUM>, and a contact section between the upper base unit <NUM> and the lower base unit <NUM> changes according to a rolling operation, as illustrated by an imaginary line in <FIG>. Needlessly to say, the lower base plate <NUM> may be a curved surface, the upper base plate <NUM> may be a flat surface, and both the upper base plate <NUM> and the lower base plate <NUM> may be curved surfaces.

The curved surface has a substantially partial spherical shape or a substantially arc-shaped cross section, in other words, the curved surface has a bowl-shape or a convex R-shape, and the upper base unit <NUM> may move in directions of <NUM> degrees including the front-rear, left-right, and diagonal directions, while rolling on the lower base unit <NUM>. The curved surface may be implemented in various modes, such as a surface that is curved at a constant curvature, even at a position separated from a reference position N which is a contact position between the two base units <NUM> and <NUM> when no load is applied, a surface having a curvature that smoothly changes as the distance from the reference position N increases, a surface having different curvature in the front-rear and left-right directions, and a surface having different curvature between the front and the rear.

As illustrated in <FIG>, the upper base plate <NUM> and the lower base plate <NUM> constitute surfaces (rolling surfaces) 312a and 322a facing each other and moving relative to each other. The upper base plate <NUM> and the lower base plate <NUM> also serve as mounting members for mounting the cover member <NUM> for hiding a gap between the rolling surfaces 312a and 322a, as described later with reference to <FIG>. On the other hand, for example, in <FIG>, in a case where the upper base plate <NUM> and the lower base plate <NUM> are provided at positions that do not form surfaces facing each other, or in a case where the cover member <NUM> is attached to a position where a part of the movement mechanism <NUM> is concealed in another mode, and the like, the bottom surface of the seat receiver <NUM> and a top surface of the support base unit <NUM> may form surfaces (rolling surfaces) facing each other. In this case, the upper base plate <NUM> and the lower base plate <NUM> are not necessarily required.

As illustrated in <FIG> and <FIG>, the elastic member <NUM> is attached to the rolling surfaces 312a and 322a in a state where a top surface 33a and a bottom surface 33b contact the rolling surfaces 312a and 322a, respectively, and the elastic member <NUM> is formed of an elastic resin foam body to form a columnar shape when no load is applied. High-elastic urethane foam, low-elastic urethane foam, and the like may be adopted as the elastic resin foam body. High-elastic urethane foam instantly deforms upon receiving an external force, and thus exerts a buffering effect. Low-elastic urethane foam gradually deforms upon receiving an external force, and thus exerts a delay effect.

In the present embodiment, the high-elastic urethane foam is adopted, because high-elastic urethane foam has low temperature dependence and excellent durability. Needlessly to say, low-elastic urethane foam may be used for the elastic member, or a thin member such as an elastic sheet may be used.

When the upper base unit <NUM> receives a load and moves in any direction of <NUM> degrees including the front-rear, left-right, and diagonal directions with respect to the lower base unit <NUM>, as illustrated in <FIG>, <FIG>, <FIG>, and the like, the rolling surface 312a of the upper base plate <NUM> moves while compressing the elastic member <NUM> between the rolling surface 312a and the rolling surface 322a of the lower base plate <NUM>, and with this movement, the upper base plate <NUM> tilts downward in a movement direction. A swing operation in which the seat <NUM> tilts downward in the movement direction according to such a movement of a seated person is realized via the upper base unit <NUM>.

Generally, it is conceivable to use, as the movement mechanism, a guide mechanism composed of a cam and a follower between an upper base unit and a lower base unit, and a link mechanism connecting the upper base unit and the lower base unit. Compared to such a structure, the movement mechanism <NUM> of the present embodiment utilizes the rolling surfaces 312a and 322a to realize an operation of the seat <NUM> in which a tilting movement component is larger than a horizontal movement component. The chair of the present embodiment that performs such an operation is particularly easy to use in a situation where a person frequently sits down and stands up from a seat.

The curvatures of the rolling surfaces 312a and 322a are set so that a gravity center position G of the seat <NUM> is lifted to G' by the movement, as illustrated by a solid line and an imaginary line in <FIG>, and the rolling surfaces 312a and 322a constitute a gravity return mechanism GRM that generates, according to a body weight, a return force for returning the seat <NUM> to the reference position N, which is a position when no load is applied.

As illustrated in <FIG> and <FIG>, the movement mechanism <NUM> is provided with a first connection member <NUM> that fixes the upper base unit <NUM> to the lower base unit <NUM> so that the upper base unit <NUM> does not separate from the lower base unit <NUM>, and regulates a relative rotation, and a second connection member <NUM> for imparting a damper function to the movement mechanism <NUM>. The damper function is imparted to suppress an abrupt movement of the seat <NUM>, considering that the movement mechanism <NUM> of the present embodiment performs a rolling operation and high-elastic urethane foam that deforms quickly is adopted as the elastic member <NUM>.

In addition, in the upper base unit <NUM>, the lower base unit <NUM>, and the elastic member <NUM>, first holes 31P to 33P for inserting a pin <NUM> constituting the first connection member <NUM> are opened along a first line L1, and second holes 31Q to 33Q for inserting a shaft <NUM> constituting the second connection member <NUM> are opened along a second line L2. The holes 31P, 32P, 33P, 31Q, 32Q, and 33Q prevent the pin <NUM> and the shaft <NUM> from interfering with the rolling surfaces 312a and 322a and the elastic member <NUM>, and thus, are also referred to as "relief holes" herein.

The first connection member <NUM> is mainly composed of three of the pins <NUM>, and the pins <NUM> are formed as an integral member with a flange unit <NUM>. The pins <NUM> are inserted through the first hole 31P of the upper base unit <NUM> (that is, the first hole 31P of the seat receiver <NUM> and the first hole 31P of the upper base plate <NUM>), the first hole 33P of the elastic member <NUM>, and the first hole 32P of the lower base unit <NUM> (that is, the first hole 32P of the lower base plate <NUM>), respectively, and the pins <NUM> are fastened from below by bolts (not illustrated) at positions where the pins <NUM> abut against the support base unit <NUM> constituting the lower base unit <NUM>. <FIG> and the like illustrate the state described above. The first holes 31P of the seat receiver <NUM> are opened at three locations corresponding to the positions of the three pins <NUM>, whereas the first hole 31P of the upper base plate <NUM> is a large opening for receiving all the three pins <NUM>.

With such a structure, for example, a relative position (distance L) between the flange unit <NUM> of the first connection member <NUM> and the support base unit <NUM> in <FIG> and <FIG> is fixed. In <FIG> and <FIG>, the elastic member <NUM> is omitted, and the upper base unit <NUM> descends almost to the maximum extent as illustrated by a solid line and approaches the lower base unit <NUM>. However, if the elastic member <NUM> is interposed and a small load is applied, the upper base unit <NUM> rises to a position indicated by the imaginary line in <FIG> and <FIG>.

When the seat <NUM> swings in the front-rear direction as illustrated in <FIG> and <FIG>, or in the left-right direction as illustrated in <FIG>, the upper base unit <NUM> is movable between the flange unit <NUM> constituting the first connection member <NUM> and the support base unit <NUM> (specifically, in a range of the distance L between the flange unit <NUM> and the lower base plate <NUM>). The upper base unit <NUM> moves while compressing the elastic member <NUM>, and thus, when the applied load is released, the upper base unit <NUM> rises by a return force of the elastic member <NUM> as illustrated in <FIG> and <FIG>, and as indicated by the imaginary line, the upper base unit <NUM> is prevented from rising further at a position where a part of the upper base unit <NUM> abuts against the flange unit <NUM>. The flange unit <NUM> prevents the upper base unit <NUM> from being detached upward, and also restricts a tilt angle when the upper base unit <NUM> is tilted to the front, rear, left, right, or diagonally.

In the present embodiment, as illustrated in <FIG>, <FIG>, and <FIG>, the flange unit <NUM> is provided inclined in the front-rear direction, so that a front end 342a is higher than a rear end 342b. That is, as illustrated in <FIG>, when the upper base unit <NUM> tilts forward, the rear end 342b of the flange unit <NUM> restricts a forward tilt angle of the upper base unit <NUM>, whereas as illustrated in <FIG>, when the upper base unit <NUM> tilts rearward, the front end 342a of the flange unit <NUM> restricts a rearward tilt angle of the upper base unit <NUM>, and a larger rearward tilt angle than the forward tilt angle is permitted. As illustrated in <FIG> and <FIG>, a left end 342c and a right end 342d of the flange unit <NUM> are at the same height position at the left and right, so that inclination of the upper base unit <NUM> is possible to the left direction and the right direction at the same angle.

As illustrated in <FIG>, <FIG>, and the like, the three pins <NUM> are each fixed to the support base unit <NUM>, and the pins <NUM> are inserted through the upper base plate <NUM> and the seat receiver <NUM>. Therefore, the upper base unit <NUM> which is a combination of the upper base plate <NUM> and the seat receiver <NUM>, is prevented from rotating with respect to the lower base unit <NUM> which is a combination of the support base unit <NUM> and the lower base plate <NUM>, and the elastic member <NUM> through which the pins <NUM> are inserted is also prevented from twisting clockwise or counterclockwise in a plan view. Needlessly to say, the number of pins is not limited to three.

As described above, the second connection member <NUM> imparts a damper effect to the operation of the movement mechanism <NUM>. Specifically, as illustrated in <FIG> and the like, the second connection member <NUM> is mainly composed of seven of the shafts <NUM> which are columnar members, and a damper mechanism DM, which is a braking mechanism, is formed by hole units 311b into which the shafts <NUM> are inserted and O-rings <NUM> made of a friction material that are arranged between the shafts <NUM> and the hole units 311b. In the present embodiment, the hole units 311b correspond to recessed units of ribs provided by forming projections and recesses at a bottom wall of the seat receiver <NUM> constituting the upper base unit <NUM>, and shaft holes <NUM> through which the shafts <NUM> pass are opened at hole bottoms of the hole units 311b. Seven sets of the shafts <NUM>, the hole units 311b, and the O-rings <NUM> are provided. Needlessly to say, the number of sets is not limited thereto.

Each of the shafts <NUM> is a bolt-shaped shaft having a large-diameter proximal end unit 351a at a lower end. In a state where the upper end side of the shafts <NUM> is inserted through the second hole 32Q of the support base unit <NUM> from the bottom surface side of the support base unit <NUM>, the proximal end unit 351a is accommodated in a recessed unit 355a of a cocoon-shaped (see <FIG>, <FIG>, and the like) abutting plate <NUM> via an elastic plate <NUM>. In this state, the abutting plate <NUM> abuts against the bottom surface of the support base unit <NUM> and is fixed with screws (not illustrated), so that the shafts <NUM> are attached in a state of protruding upward from the support base unit <NUM>, as illustrated in <FIG>.

As illustrated in <FIG>, <FIG>, <FIG>, and the like, the proximal end unit 351a has a spherical or flat spherical shape, and combined with the elastic deformation of the elastic plate <NUM> interposed between the proximal end unit 351a and the abutting plate <NUM>, the shaft <NUM> is connected to the support base unit <NUM> of the lower base unit <NUM> to be swingable around the proximal end unit 351a. That is, the proximal end unit 351a of the shaft <NUM>, the elastic plate <NUM>, and the recessed unit 355a of the abutting plate <NUM> form a non-directional joint UJ (see <FIG>). Needlessly to say, another configuration such as a ball joint may be employed as a non-directional joint in which the shaft <NUM> is swingable around the proximal end.

The shafts <NUM> protrude upward via the second hole 32Q of the lower base unit <NUM> (that is, the second hole 32Q of the support base unit <NUM> and the second hole 32Q of the lower base plate <NUM>), the second hole 33Q of the elastic member <NUM> (not illustrated in <FIG>), and the second hole 31Q of the upper base unit <NUM> (that is, the second hole 31Q of the upper base plate <NUM> and the second hole (shaft hole) 31Q of the seat receiver <NUM>). The shafts <NUM> constitute the damper mechanism DM.

On the other hand, as illustrated in <FIG>, <FIG>, <FIG>, and the like, a return spring <NUM> serving as a third connection member is interposed around an outer periphery of the shaft <NUM> to be interposed between the upper base unit <NUM> and the lower base unit <NUM> and connect the upper base unit <NUM> and the lower base unit <NUM>. In the present embodiment, the return spring <NUM> is a coil spring. In three of the seven second holes 31Q to 33Q described above, a recessed retainer unit 322R that supports a lower end of the return spring <NUM> in a positioned state is formed on the lower base plate <NUM> of the lower base unit <NUM>, and the second holes 33Q (R) and 31Q (R) opened at three locations of the elastic member <NUM> and the upper base plate <NUM> have a larger diameter than the return spring <NUM>. A recessed retainer unit 311R that accommodates an upper end of the return spring <NUM> in a positioned state is formed in three corresponding locations among the seven locations where the second holes 31Q are provided in the bottom surface of the seat receiver <NUM> constituting the upper base unit <NUM>.

The return spring <NUM> is arranged at a plurality of locations (three locations in the present embodiment) over a range of <NUM> degrees or more (for example, <NUM> degrees) around a center position (reference numeral O in <FIG>) of the movement mechanism <NUM>. Therefore, if the upper base unit <NUM> is tilted in any direction including the front-rear, left-right, and diagonal directions, the return spring <NUM> on the tilted side is compressed, and the return spring <NUM> assists the return force for returning the upper base unit <NUM> to the reference position N when no load is applied. The back <NUM> is integrally attached to the seat <NUM>, and thus, the return spring <NUM> also supports a load of a movable portion including the seat <NUM> and the back <NUM>. A structure in which the return spring <NUM> on the side opposite to the tilted side is pulled may be adopted as the configuration of the return spring <NUM>.

As described above, the second connection member <NUM> has a configuration in which the O-rings <NUM> made of a friction material are fitted between the shafts <NUM>, which are columnar members, and the hole units 311b.

Specifically, as illustrated in <FIG>, the shaft holes <NUM> open in a bottom wall 311a of the seat receiver <NUM> constituting the upper base unit <NUM>, and the periphery of the bottom wall 311a constitutes the hole units 311b that have a tapered shape and open upward.

On the other hand, as illustrated in <FIG>, <FIG>, <FIG>, <FIG>, and the like, a pressing tool <NUM> has a C-shape in a plan view. The pressing tool <NUM> includes an end unit 356a facing the bottom wall 311a, and a periphery of the end unit 356a constitutes a projecting unit 356b that has a tapered shape and protrudes downward.

An inner diameter of the O-rings <NUM> is chosen so that the O-rings <NUM> fit with the shafts <NUM> with a predetermined sliding resistance, and the predetermined sliding resistance is chosen so that a required damper effect can be obtained when the seat <NUM> swings. In the present embodiment, NBR rubber is used for the O-rings <NUM>. However, the material is not limited thereto, and various materials may be adopted as the material for realizing the sliding resistance.

The shafts <NUM> are passed through the shaft holes <NUM> and fitted to the O-rings <NUM> from above, and the pressing tool <NUM> is pushed from above to fit the projecting unit 356b into the hole unit 311b. Thus, the O-rings <NUM> are pressed against the bottom wall 311a of the seat receiver <NUM> by the end unit 356a to realize the assembled state illustrated in <FIG>, <FIG>, and the like. In this state, the pressing tool <NUM> is fastened to a top surface of the seat receiver <NUM> by bolts V1 illustrated in <FIG>, <FIG>, and the like, so that the O-rings <NUM> are fixed to the seat receiver <NUM> and therefore the upper base unit <NUM>, as illustrated in <FIG>. At this time, the O-ring <NUM> illustrated in <FIG> is deformed into a flat elliptical shape, and abuts against the outer periphery of the shaft <NUM> not at a point, but at a surface having an area of a certain size or more.

If the upper base unit <NUM> swings, as illustrated in <FIG>, <FIG>, and the like, the O-rings <NUM>, which are friction members fitted to the shafts <NUM> while being attached to the seat receiver <NUM> of the upper base unit <NUM>, change a fitting position with respect to the shafts <NUM>, which are columnar members in which the proximal end unit 351a is swingably attached to the lower base unit <NUM>, while sliding along the shafts <NUM> together with the hole units 311b. The shafts <NUM> swing in response to the swinging of the O-rings <NUM> and follow the change in angle of the upper base unit <NUM> with respect to the lower base unit <NUM>. At this time, a relative movement of the hole units 311b and the O-rings <NUM>, which are friction members, with respect to the shafts <NUM>, which are columnar members constituting the damper mechanism DM, is a sliding motion along a longitudinal direction of the shafts <NUM>. The shafts <NUM> may be formed of a bendable and flexible material. In this case, the hole units 311b and the O-rings <NUM> can move along the longitudinal direction of the shafts <NUM>, without swingably supporting the shafts <NUM>.

That is, the damper mechanism DM is arranged at a plurality of locations around a center position of the upper base unit <NUM> over a range of <NUM> degrees or more (for example, <NUM> degrees). Therefore, if the seat <NUM> moves in any direction of <NUM> degrees, the shafts <NUM> and the O-rings <NUM> operate while following the movement of the seat <NUM> and sliding relative to each other, and exert a damper action by a sliding resistance in both directions of an operation in which a distance between the upper base unit <NUM> and the lower base unit <NUM> is expanded or contracted.

In a chair having such a configuration, in a state where no seating load is applied, the gravity return mechanism GRM mentioned above attempts to return the chair to a position (reference position) where the center of gravity of the movable portion including the upper base unit <NUM>, the seat <NUM>, and the back <NUM> is lowest. At that time, a restoring force of the elastic member <NUM> and an auxiliary restoring force of the return spring <NUM> act together, and thus, the chair stops at the overall most stable position. <FIG> illustrate a state where the seat <NUM> is in the reference position N.

The seat <NUM> of the chair can swing from the reference position N in any direction of <NUM> degrees including the front-rear, left-right, and diagonal directions, when the upper base plate <NUM> performs a rolling operation with respect to the lower base plate <NUM>.

In the rolling surfaces performing such a rolling operation, the upper base plate <NUM> and the lower base plate <NUM>, which are surfaces facing each other, include the first holes 31P and 32P for passing the pins <NUM> constituting the first connection member as illustrated in <FIG>, the second holes 31Q and 32Q for passing the shafts <NUM> constituting the second connection member as illustrated in <FIG>, the recessed retainer unit 322R (see <FIG> and <FIG>) for accommodating the return spring <NUM> which is the third connection member, a return spring insertion hole in the upper base plate <NUM>, and the like. In particular, the first hole 31P in the upper base plate <NUM> illustrated in <FIG> is a hole having a large opening to avoid interference with the three pins <NUM>, and the second holes 31Q and 32Q illustrated in <FIG> are provided for each of the shafts <NUM>, so that the number of the second holes 31Q and 32Q is large. As illustrated in <FIG>, <FIG>, and the like, three of the second holes 31Q and 32Q have a large diameter so that the return spring <NUM> can also pass through.

In the holes 31P, 32P, 31Q, 32Q, and the like, regions having different so-called curvatures are formed and the continuity of the rolling surfaces 312a and 322a is impaired. Therefore, if the upper base plate <NUM> constituting the upper base unit <NUM> rolls directly on the lower base plate <NUM> constituting the lower base unit <NUM>, the upper base unit <NUM> is likely to rattle due to the change in the curvature. The rattling propagates as a rattling of the seat <NUM>.

On the other hand, in the present embodiment, the elastic member <NUM> is interposed between the above-described region in one of the upper base unit <NUM> and the lower base unit <NUM> and a corresponding region in the other one of the upper base unit <NUM> and the lower base unit <NUM>. The elastic member <NUM> lowers the stability when opening peripheral edges of the holes 31P, 31Q, and the like existing in the rolling surface 312a of the upper base unit <NUM> abut against the rolling surface 322a of the lower base unit <NUM> facing the rolling surface 312a, and lowers the stability when opening peripheral edges of the holes 32P and 32Q existing in the rolling surface 322a of the lower base unit <NUM> abut against the rolling surface 312a of the upper base unit <NUM> facing the rolling surface 322a. That is, the elastic member <NUM> facilitates rolling between the rolling surfaces 312a and 322a at a place where the curvature of the rolling surfaces 312a and 322a changes and smooths the change of the curvature. Needlessly to say, even in a place where no hole is formed, and also a place where the surface of the rolling surfaces 312a and 322a is irregular or deteriorated, the elastic member has an effect of reducing the rattling caused by the irregular or deteriorated surface.

As illustrated in <FIG>, <FIG>, and the like, the distance between the upper base unit <NUM> and the lower base unit <NUM>, which are rolling surfaces facing each other, is smaller on the side to which the upper base unit <NUM> is tilted and larger on the opposite side. The elastic member <NUM> is interposed between the upper base unit <NUM> and the lower base unit <NUM>, and thus, the elastic member <NUM> is elastically restored on the larger side and the elastic member <NUM> is compressed on the smaller side, until a thickness of the elastic member <NUM> is very small. The elastic member <NUM> accommodates the pins <NUM> that form the main body of the first connection member <NUM> and the shafts <NUM> that form the second connection member <NUM> in the first holes 33P and the second holes 33Q, and thus the elastic member <NUM> conceals the pins <NUM> and shafts <NUM> as viewed sideways. However, the elastic member <NUM> does not hide a gap between the upper base unit <NUM> and the lower base unit <NUM>, and thus, does not include a function of preventing foreign bodies from entering the gap. Unlike between the rolling surfaces 312a and 322a, there is no direct or indirect contact, however, it is also necessary to hide a region between a pair of swinging surfaces including surfaces facing each other, and thus the circumstance is common.

Therefore, in the present embodiment, as illustrated in <FIG>, <FIG>, and the like, the elastic member <NUM> is arranged at a portion extending from the vicinity of outer peripheral edges 312z and 322z of both swinging surfaces 312a and 322a facing each other to the inside thereof, and a stretchable sheet material <NUM> is provided between the outer peripheral edges 312z and 322z to conceal a gap between the swinging surfaces 312a and 322a facing each other, including the elastic member <NUM>.

Specifically, grooves 312x and 322x extending along the outer peripheral edges 312z and 322z and opening in opposite directions are provided in the vicinity of the outer peripheral edges 312z and 322z of the swinging surfaces 312a and 322a facing each other, and in the cover member <NUM>, deformable strips <NUM> and <NUM> are attached to edge portions of the stretchable sheet material <NUM>. As illustrated in <FIG>, the strips <NUM> and <NUM> are sequentially pushed into the grooves 312x and 322x to be mounted to the grooves 312x and 322x. As a result, the cover member <NUM> conceals a gap between the upper base plate <NUM> and the lower base plate <NUM>, which form facing swinging surfaces. The strips <NUM> and <NUM> may be mounted to the grooves 312x and 322x in any order.

For example, the stretchable sheet material <NUM> is formed by using a material obtained by knitting polyester fibers. In the present embodiment, the stretchable sheet material <NUM> is sewn or formed into a cylindrical shape, and the strips <NUM> and <NUM> made of resin and having an annular thin plate shape are integrally provided at the upper end and the lower end of the stretchable sheet material <NUM>. The size and elasticity of the stretchable sheet material <NUM> are chosen so that no wrinkles are generated when the gap is most narrow and so that the stretchable sheet material <NUM> does not hinder the operation of the swinging surface when the gap is widened. The relationship between the grooves 312x and 322x and the strips <NUM> and <NUM> is one-to-one, and each of the strips <NUM> and <NUM> corresponds to the entire area of one of the grooves 312x and 322x, and the strips <NUM> and <NUM> are provided having a length that surrounds the grooves 312x and 322x. Needlessly to say, the material of the stretchable sheet material <NUM> is not limited to the above-described materials, and various materials such as cloth, upholstery, woven fabric, and knitted items can be used, as long as the material can be stretched and contracted and covers the inside. The stretchable sheet material <NUM> that can hide the inside is used, but the stretchable sheet material <NUM> may be a material through which the inside is slightly visible.

As illustrated in <FIG>, <FIG>, and the like, when the upper base unit <NUM> moves with respect to the lower base unit <NUM>, the cover member <NUM> follows the movement by deforming, in addition to stretching and contracting, according to the movement of the gap between the rolling surfaces 312a and 322a and continues to conceal the gap expanding and contracting between the upper base unit <NUM> and the lower base unit <NUM>.

As illustrated in <FIG>, the back <NUM> is provided with a back main body <NUM> at an upper end of a back support rod <NUM>, and is attached to the seat <NUM> to swing together with the seat <NUM> as described above. Specifically, as illustrated in <FIG>, a rear edge 132a of the outer seat shell <NUM> is provided with a flat insertion port 132b that opens rearward. On the other hand, a lower end front edge 41a of the back support rod <NUM> constituting the back <NUM> has a shape in accordance with the rear edge 132a of the outer seat shell <NUM>, and an insertion unit 41b that can be inserted into the insertion port 132b of the outer seat shell <NUM> is provided. The insertion unit 41b is inserted into the insertion port 132b, and then bolts (not illustrated) are inserted into bolt holes 132c and 41c to join the insertion unit 41b and the insertion port 132b. A wooden material is used for the back main body <NUM> of the present embodiment.

As illustrated in <FIG>, the arms <NUM> are provided with arm rests <NUM> at upper ends of an arm rod <NUM>, and are attached not to swing with respect to the seat <NUM> and the back <NUM> as described above. Specifically, as illustrated in <FIG> and <FIG>, an arm mounting location <NUM> is set at a rear portion of the bottom surface of the support base unit <NUM> where the cocoon-shaped abutting plate <NUM> is not provided. On the other hand, the left and right arm rests <NUM> are connected by the arm rod <NUM>, and a proximal end of the arm rod <NUM> is attached to a common bracket <NUM>. The bracket <NUM> is arranged at the arm mounting location <NUM>, and a bolt (not illustrated) is fastened through a hole 53a of the bracket <NUM> and a hole <NUM> provided in the bottom surface of the support base unit <NUM> from below. The arm rod <NUM> extends from this position to the left or right along the bottom surface of the seat <NUM>, rises upward from the vicinity of the rear edge of the seat <NUM>, and then extends forward. The arm rests <NUM> are arranged at the portions of the arm rod <NUM> extending forward.

As described above, the chair of the present embodiment includes the movement mechanism <NUM> that causes the upper base unit <NUM> to swing in a direction of <NUM> degrees with respect to the lower base unit <NUM>, and the seat <NUM> attached to the upper base unit <NUM>. Further, the chair of the present embodiment is provided with the damper mechanism DM that may operate by following a movement in a direction of <NUM> degrees, as a mechanism separate from the movement mechanism <NUM>, at a position connecting the upper base unit <NUM> and the lower base unit <NUM>.

According to such a configuration, the upper base unit <NUM> can follow a free movement of the seated person in the front-rear, left-right, and diagonal directions by the movement mechanism <NUM>, and the seated person can easily find a weight balance while supporting his or her own weight, and can change his or her posture stably and continuously. In particular, instead of imparting resistance to the movement mechanism <NUM>, the damper mechanism DM is provided as a mechanism separate from the movement mechanism <NUM>, and thus, it is possible to adjust a working condition of the damper mechanism DM, without changing the basic performance of the movement mechanism <NUM>.

Specifically, in the movement mechanism <NUM>, the surface 312a, which is one of the surfaces 312a and 322a of the upper base unit <NUM> and the lower base unit <NUM> facing each other, forms a curved rolling surface, and the upper base unit <NUM> rolls with respect to the lower base unit <NUM>, so that the seat <NUM> provided in the upper base unit <NUM> swings.

Thus, the upper base unit <NUM> rolls on the lower base unit <NUM> using the rolling surfaces 312a and 322a, and thus, the upper base unit <NUM> can tilt while rolling continuously and smoothly in the front-rear, left-right, and diagonal directions according to the movement of the seated person. The seated person can perform a stable tilting motion while balancing a load of the seated person on the rolling surfaces 312a and 322a, and thus, the safety is also ensured.

The movement mechanism <NUM> of the present embodiment causes the upper base unit <NUM> to tilt downward in the movement direction of the seat <NUM>, as the seat <NUM> moves away from the reference position N, regardless of which direction of <NUM> degrees the seat <NUM> moves in from the reference position N.

In such a configuration, a rolling movement is easily generated particularly by a load applied in the movement direction, and thus, the damper mechanism DM of the present embodiment is an effective damper mechanism.

The damper mechanism DM of the present embodiment can be arranged at a plurality of locations around a predetermined center O of the seat <NUM>, and may operate in at least one direction or both directions of an operation in which the distance between the upper base unit <NUM> and the lower base unit <NUM> expands or contracts.

Therefore, the damper mechanism DM can be surely operated, regardless of which direction of <NUM> degrees the seat <NUM> swings in. In particular, a degree of freedom in design can be obtained by utilizing at least one of the operations of expanding or contracting the distance between the upper base unit <NUM> and the lower base unit <NUM>, and if both operations are utilized, the damper effect can be doubled.

The damper mechanism DM is provided between the upper base unit <NUM> and the lower base unit <NUM>, and connected by a non-directional joint UJ at least to the lower base unit <NUM>.

Therefore, the damper mechanism DM can follow the front-rear and left-right movements of the seat <NUM> from the reference position N, but also a movement in a rotation direction, so that the damper mechanism DM can appropriately adapt to a free movement of the seat <NUM>.

The damper mechanism DM includes the hole units 311b provided in any one of the upper base unit <NUM> and the lower base unit <NUM>, the shafts <NUM> which are columnar members provided in the other one of the upper base unit <NUM> and the lower base unit <NUM> and inserted into the hole units 311b, and the O-rings <NUM> which are friction materials arranged between the hole units 311b and the shafts <NUM>.

According to such a configuration, if the upper base unit <NUM> moves relative to the lower base unit <NUM>, the O-rings <NUM> slide with respect to the shafts <NUM> at a predetermined sliding resistance, and thus, it is easy to apply a uniform damper effect. The sliding resistance can be adjusted by adapting the shape of the O-rings <NUM>.

The relative movement of the damper mechanism DM of the present embodiment is a sliding motion of the hole units 311b and the O-rings <NUM> along the longitudinal direction of the shafts <NUM>.

Thus, the operation of the damper mechanism DM is simplified, so that stable operation can be ensured for a long period of time.

In the present embodiment, the elastic member <NUM> that can be elastically deformed is provided between the upper base unit <NUM> and the lower base unit <NUM>, and the upper base unit <NUM> moves while compressing the elastic member <NUM> between the upper base unit <NUM> and the lower base unit <NUM>.

With such a configuration, as compared to a case where the upper base unit <NUM> rolls directly on the lower base unit <NUM>, it is possible to obtain a softer sitting feel and it is also possible to prevent generation of undesirable noise. The elastic member <NUM> is compressed with the movement of the upper base unit <NUM>, and thus, even in a structure in which the upper base unit <NUM> easily rolls via the rolling surfaces 312a and 322a, the elastic member <NUM> attenuates an abrupt operation of the upper base unit <NUM>. Therefore, the elastic member <NUM> is useful for ensuring safety, and the elastic member <NUM> can prevent a situation where the upper base unit <NUM>, when returning to the reference position N, does not easily return from a position after the rolling movement due to the damper effect of the damper mechanism DM.

In the present embodiment, the return spring <NUM> for returning the upper base unit <NUM> toward the predetermined reference position N is interposed between the upper base unit <NUM> and the lower base unit <NUM>.

If the return spring <NUM> is provided, the return spring <NUM> prevents the upper base unit <NUM> from moving abruptly when moving away from the reference position N, and the return spring <NUM> can prevent a situation where the upper base unit <NUM>, when returning to the reference position N, does not easily return from a position after the rolling movement due to the damper effect of the damper mechanism DM.

In the present embodiment, the gravity return mechanism GRM that generates a return force toward the reference position N by raising the position of the center of gravity of the movable portion including the upper base unit <NUM>, according to the movement of the upper base unit <NUM> from the reference position N, is provided between the upper base unit <NUM> and the lower base unit <NUM>.

Thus, as compared with a case where the return force toward the reference position N depends only on a spring, it is possible to generate an appropriate return force according to the body weight. Moreover, adopting the gravity return mechanism GRM when the effect achieved by the damper mechanism DM alone is insufficient, makes it possible to appropriately suppress the movement of the seat, because the mechanism GRM also has a damper function. The gravity return mechanism GRM can prevent a situation where the upper base unit <NUM>, when returning to the reference position N, does not easily return from a position after the rolling movement due to the damper effect of the damper mechanism DM.

Provided is an unprecedented chair which has a simple structure and in which a seat can follow a free movement of a seated person in front-rear, left-right, and diagonal directions, a burden from an operation by which the seated person balances his or her load can also be reduced, and a movement by which the seated person changes his or her posture stably and continuously can be suitably supported.

Claim 1:
A chair comprising:
a movement mechanism (<NUM>) that causes an upper base unit (<NUM>) to swing in a direction of <NUM> degrees with respect to a lower base unit (<NUM>); and
a seat (<NUM>) attached to the upper base unit (<NUM>), wherein
the chair further comprises a damper mechanism (DM) as a mechanism separate from the movement mechanism (<NUM>), at a position connecting the upper base unit (<NUM>) and the lower base unit (<NUM>), the damper mechanism (DM) operating by following a movement in a direction of <NUM> degrees;
characterized in that
the chair further comprises
a gravity return mechanism (GRM) that generates a return force toward a reference position (N) by raising a position of a center of gravity of a movable portion including the upper base unit (<NUM>), in accordance with a movement of the upper base unit (<NUM>) from the reference position (N), wherein the gravity return mechanism (GRM) is provided between the upper base unit (<NUM>) and the lower base unit (<NUM>),
wherein the damper mechanism (DM) includes a hole unit (311b) provided in one of the upper base unit (<NUM>) and the lower base unit (<NUM>), a columnar member (<NUM>) provided in the other one of the upper base unit (<NUM>) and the lower base unit (<NUM>) and inserted into the hole unit (311b), and a friction material (<NUM>) arranged between the hole unit (311b) and the columnar member (<NUM>).