CHAIR

Abstract

A chair includes: a seat body having a seating surface which provides seating to a user; a support device that supports the seat body such that the seat body is movable along a front-to-rear direction of the chair within a predetermined range; and an urging device. When the seat body is located in an area between a front position and a first reference position, the support device supports the seat body such that the seat body is moved to the front position by own weight. When the seat body is located between a rear position and a second reference position, the urging device urges the seat body toward the front position, whereas, when the seat body is located between the second reference position and the front position, the urging device does not urge the seat body.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application No. 2011-003150 filed on Jan. 11, 2011 in the Japanese Patent Office, the disclosure of which is incorporated herein by reference.

BACKGROUND

This invention relates to a chair used in combination with a desk. More particularly, the present invention is related to a chair configured so as to be movable (swingable) between a front position and a rear position.

In a lecture room at school, for example, desks and chairs are disposed in alignment. Chairs used in such a place are configured so as to be movable (swingable) between a front position and a rear position so that people can easily move through between a desk and a chair. Specifically, the chair used in such a place is constituted in a manner that a seat body, which provides seating to a user, can be moved rearward, when a user is seated, and the seat body can be moved to the front position, when nobody is seated.

Such chair is preferably configured in a manner that, when nobody is seated, the seat body is reliably located at the front position. In order to move the seat body to the front position, the chair is provided with, in some cases, an urging device that urges the seat body of the chair, or that urges a support device supporting the seat body. However, in a chair provided with such urging device, when the seat body is moved to the front position, the seat body or the support device may collide against a stopper and the like, due to the urging force of the urging device. The chair may be broken because of the shock of the collision. Or loud collision noise may be generated and gives an unpleasant feeling to a user and other people.

In order to solve this problem, a chair is suggested (see publications of Unexamined Japanese Utility Model Publication No. 05-21745 and Unexamined Japanese Patent Publication No. 2008-272456) wherein a shock-absorbing device is provided so as to restrict the speed of a seat body moving to a front position. In such chair, the speed of the seat body moving to the front position is restricted by the shock-absorbing device, such as a damper or a compression spring. Therefore, the shock generated when the seat body is moved to the front position can be reduced.

SUMMARY

In the above-described conventional chair, the urging device constantly urges the seat body in a direction so as to move the seat body forward. Thus, even if a shock-absorbing device is provided, shock cannot be sufficiently reduced in some cases. Moreover, there has been a problem in that, when the movement of the seat body from the front position to the rear position is initiated, extremely large force is required so as to oppose the urging force.

A chair is preferably provided wherein the shock, generated when a seat body is moved to a front position, can be reduced, and the seat body can be easily moved.

The present invention, which is made in order to solve the above-described and other problems, provides a chair including: a seat body having a seating surface which provides seating to a user; a support device that supports the seat body such that the seat body is movable along a front-to-rear direction of the chair within a predetermined range; and an urging device.

When the seat body is located in an area between a front position, which is a limit in a front side of the predetermined range, and a first reference position, located behind the front position, the support device supports the seat body such that the seat body is moved to the front position by own weight.

When the seat body is located between a rear position, which is a limit in a rear side of the predetermined range, and a second reference position, located between the first reference position and the front position, the urging device urges the seat body toward the front position, whereas, when the seat body is located between the second reference position and the front position, the urging device does not urge the seat body.

The position of the seat body may be understood as a position of a center portion (center in the front-to-rear direction) of members constituting the seat body, or as a position of an entire portion of the seat body.

In the chair configured as above, when the seat body is located between the rear position and the second reference position, the seat body is urged by the urging device and moved at least to the second reference position. In this case, the seat body can be located at the first reference position, or in the front side of the first reference position. As a result, the seat body can be moved to the front position by own weight. In other words, in the above-described chair, as long as the seat body is free from external load, for example, manually pulling the seat body and the like, the seat body can be automatically moved to the front position.

The urging device stops urging the seat body, when the seat body is moved into the front side of the second reference position. That is, when the seat body is moved to the front position, the seat body is no longer under influence of the urging force of the urging device. Therefore, as compare to a case wherein the urging force is continuously applied to a seat body until the seat body is moved to the front position, in the chair according to the present invention, shock that can be generated when the seat body is moved to the front position can be reduced.

In the following, a case is considered wherein a seat body is moved from the front position to the rear position by, for example, manually pulling the seat body. In order to start moving the seat body from a stationary state of the seat body, larger force is initially required. That is because frictional coefficient becomes larger when the seat body is stationary. In addition, if urging force toward the front side is applied to the seat body by the urging device, even larger force is required so as to start moving the seat body. However, in the chair according to the present invention, the seat body does not receive the urging force of the urging device in vicinity of the front position as described above. Therefore, the present invention can inhibit the force, required so as to start moving the seat body, from being large. As a result, the movement of the seat body can be smoothly and easily initiated.

One of the characteristics of the chair according to the present invention is that, when the seat body is located in the front side of the first reference position, the seat body can move to the front position by own weight. Own weight is not only the weight of the seat body, but the weight of the support device supporting the seat body can be also included. Being moved by own weight means that the seat body moves to the front position, and can also means that the support device, supporting the seat body, moves (makes motion) together.

The position of the second reference position may be substantially equivalent to the first reference position. The structure of the chair is required merely to be such that when the seat body is moved forward from the rear position by the urging device, and reaches a position wherein the seat body is no longer urged by the urging device, the seat body is moved forward by own weight.

The urging device may be configured so as to urge the seat body by directly applying load, or by applying the load to the members connected to the seat body.

Moreover, various ways may be adopted in order to achieve the structure wherein the urging force of the urging device is not applied to the seat body when the seat body is moved in the front side of the second reference position.

In one example, the urging device may include a pressing portion that comes in contact with and comes away from a predetermined surface of the seat body or of the support device. The urging device may be constituted in such a manner that, when the seat body is located between the rear position and the second reference position, the pressing portion comes in contact with the predetermined surface and presses the predetermined surface so as to urge the seat body toward the front position, and that, when the seat body is located between the second reference position and the front position, the pressing portion comes away from the predetermined surface so as not to urge the seat body. In the chair constituted as above, when the seat body is moved in the front side of the second reference position, the pressing portion comes away from the predetermined surface, and no longer presses the predetermined surface. Therefore, the seat body can be urged forward only when the seat body is located in the back side of the second reference position.

The chair according to the present invention may include a shock-absorbing device that restricts moving speed of the seat body toward the front position.

According to this structure, the speed of the seat body moving to the front position can be small due to the shock-absorbing device (for example, a damper). Therefore, the shock that can be caused when the seat body is moved to the front position can be further reduced.

It is to be noted that the shock-absorbing device may be constituted so as to be able to restrict the moving speed of the seat body irrespective of the position of the seat body. The shock-absorbing device may be constituted so as to restrict the moving speed of the seat body, for example, throughout the movable range of the seat body, or only in one part of the range. For example, if the shock-absorbing device works between the rear position and the second reference position and the moving speed of the seat body is restricted, the shock, generated when the seat body is moved to the front position, can be reduced.

Moreover, the shock-absorbing device may be constituted so as to restrict the moving speed of the seat body toward the front position, only when the seat body is located in an area between the second reference position and the front position.

In the chair constituted as above, the shock-absorbing device does not work when the seat body is located in an area between the rear position and the second reference position. In other words, in a state wherein the seat body receives the urging force of the urging device, the shock-absorbing device does not work and the speed is not restricted by the shock-absorbing device. Thus, the seat body can be smoothly moved to the front position. On the other hand, when the seat body is located in an area between the second reference position and the front position, the shock-absorbing device works and the moving speed of the seat body, moving only by own weight, can be restricted in the vicinity of the front position. Because the shock-absorbing device works in the vicinity of the front position under the situation wherein the seat body is moved only by own weight, the shock that can be generated when the seat body comes to a stop can be extremely small.

The structure of the support device is not specifically limited, and various structures may be adopted.

In one example, the support device may include: a leg support installed on a floor surface; and a swing portion that supports the seat body and has one end thereof connected to the leg support so as to be swingable in the front-to-rear direction around where the one end is connected.

In the chair constituted as above, the seat body can be moved by the swinging of the swing portion.

It is to be noted that the shape of the swing portion is not specifically limited. Moreover, the swing portion may be constituted with one piece of columnar member, or with a plurality of columnar members.

Various members can be used as the urging device. In one example, the urging device may be a gas spring.

By using a gas spring as the urging device, the urging speed so as to urge the seat body can be easily and reliably controlled. That is, the moving speed of the seat body when the seat body is moved to the front position can be restricted and the shock can be reduced.

The chair according to the present invention may be configured as follows: the urging device is a gas spring; the support device includes a leg support installed on a floor surface, and a swing portion that supports the seat body and has one end thereof connected to the leg support so as to be swingable in the front-to-rear direction around where the one end is connected; the chair further includes a link arm having one end connected to one end of the gas spring via a first rotational shaft so as to be rotatable around the first rotational shaft, and another end connected to the swing portion via a second rotational shaft, disposed at a distance from the first rotational shaft, so as to be rotatable around the second rotational shaft; another end of the gas spring is connected to a third rotational shaft, disposed in a position in which a distance from the second rotational shaft changes corresponding to movement of the seat body, so as to be rotatable around the third rotational shaft; and the gas spring may urge the seat body to the front position by one of ways of extending and being compressed, when the seat body is located between the second reference position and the rear position.

According the above-described construction, the swing portion swings forward due to the gas spring extending or being compressed. Consequently, the seat body is moved forward (moved to the front position).

Moreover, the gas spring does not urge the seat body, when the seat body is located between the second reference position and the front position. Therefore, the shock that can be generated when the seat body is moved to the front position can be reduced.

Furthermore, one end of the gas spring is connected to the link arm. The link arm is connected to the swing portion. When the seat body is moved, the distance between the second rotational shaft and the third rotational shaft (to be also referred to as connection distance) changes. The above-mentioned connection distance can be changed even without the gas spring extending or being compressed, because one end of the gas spring is connected to the swing portion via the link arm, and the link arm is rotated with respect to the gas spring and the swing portion.

Therefore, when the seat body is moved between the second reference position and the front position, the connection distance can be changed without extending or compressing the gas spring. Due to this mechanism, the structure can be achieved wherein the gas spring does not urge the seat body when the seat body is located between the second reference position and the front position.

If one end of the gas spring is connected to the rotational shaft fixed to the swing portion and the gas spring is consistently extended/compressed corresponding to the movement of the seat body, the urging force of the gas spring is applied to the seat body whenever the seat body is moved irrespective of the position of the seat body.

The chair according to the present invention may be further provided with a rotary damper disposed on at least one of the first and the second rotational shafts so as to restrict the moving speed of the seat body toward the front position.

Due to this structure, the speed of the seat body when the seat body is moved to the front position can be small by the shock-absorbing effect of the rotary damper. Therefore, the shock that can be generated when the seat body is moved to the front position can be further reduced.

The position of the rotary damper is not specifically limited. Moreover, an alternative shock-absorbing device other than the rotary damper may be provided.

The chair according to the present invention may be constituted such that the swing portion is provided with an abutment surface pressed by one of the gas spring and the link arm when the gas spring extends. Due to this structure, the gas spring can urge the seat body by pressing the abutment surface.

Furthermore, in the chair according to the present invention may be constituted as follows: the urging device is a gas spring; the support device includes a leg support, installed on a floor surface, and a swing portion having one end thereof connected to the leg support and another end thereof connected to the seat body so as to be swingable around the leg support; one end of the gas spring is engaged with an elongate hole, formed on the swing portion, so as to be slidable in the elongate hole; and another end of the gas spring is attached to a rotational shaft so as to be rotatable around the rotational shaft. The rotational shaft is disposed in a position in which a distance from the elongate hole changes corresponding to movement of the seat body.

Due to this structure, the swing portion swings forward by the gas spring extending or being compressed. Consequently, the seat body is moved to the front position. The gas spring does not urge the seat body when the seat body is located between the second reference position and the front position. Therefore, the shock that can be generated when the seat body is moved to the front position can be reduced.

Moreover, in the chair according to the present invention, one end of the gas spring is engaged with the elongate hole formed on the swing portion. When the seat body is moved, the distance between the elongate hole and the rotational shaft disposed on the other end of the gas spring (connection distance) changes. The connection distance can be changed by one end of the gas spring sliding inside the elongate hole, without the gas spring extending or being compressed, because one end of the gas spring is engaged with the elongate hole.

Therefore, when the seat body is moved between the second reference position and the front position, the connection distance can be changed without extending/compressing the gas spring. As a result, the structure can be achieved wherein the gas spring does not urge the seat body when the seat body is located between the second reference position and the front position.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described below, by way of example, with reference to the accompanying drawings. However, it is to be noted that the embodiment described below is merely an example, and that the present invention can be carried out in various ways other than the embodiment explained below. In the drawings for the exemplary embodiment:

FIG. 1 is a side view showing a chair according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a front leg and a rear leg of the chair according to the embodiment;

FIGS. 3A-3D are side views explaining movement of a seat body of the chair according to the embodiment;

FIGS. 4A-4B are side views showing a chair according to a variation of the present invention;

FIGS. 5A-5C are side views showing a chair according to another variation of the present invention;

FIGS. 6A-6B are side views showing a chair according to a further variation of the present invention;

FIGS. 7A-7B are side views showing a chair according to a yet another variation of the present invention; and

FIGS. 8A-8B are side views showing a chair according to a still further variation of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) Entire Structure

As shown in FIG. 1, a chair 1 according to the present embodiment includes a seat body 10, a leg support 20 installed on a floor surface, a front leg 30, and a rear leg 40. One ends (lower ends) of the front leg 30 and the rear leg 40 are respectively connected to the leg support 20, whereas the other ends (upper ends) thereof are respectively connected to the seat body 10. The chair 1 is used in a place such as a lecture room, in combination with a desk 2, and a plurality of such combinations is aligned in a front-to-rear and a left-to-right directions of the room. It is to be noted that in FIGS. 1 and 3-7, some portions of the chair 1 are shown with solid lines in order to clearly show the constituents of the chair 1, although these portions are actually hidden behind some other portions and cannot be seen.

The seat body 10 is provided with a seating surface 11 and a backrest 12. In use of the chair 1, a user can manually pull (or lean on) the backrest 12 rearward so as to move the seat body 10 away from the desk 2, and be seated on the seating surface 11.

The seat body 10 is provided with a seat support 13 in a backside area opposite to the seating surface 11. The seat support 13 is provided with a first shaft 14, connected to the upper end of the front leg 30, and a second shaft 15, disposed behind the first shaft 14 (in the right direction in FIG. 1) and connected to the upper end of the rear leg 40.

The leg support 20 is provided with a third shaft 21, connected to the lower end of the front leg 30, and a fourth shaft 22, disposed behind the third shaft 21 (in the right direction in FIG. 1) and connected to the lower end of the rear leg 40.

The front leg 30 is configured in a manner such that one end thereof is rotatable with respect to the seat body 10 around the first shaft 14, and the other end thereof is rotatable with respect to the leg support 20 around the third shaft 21. The rear leg 40 is configured in a manner such that one end thereof is rotatable with respect to the seat body 10 around the second shaft 15, and the other end thereof is rotatable with respect to the leg support 20 around the fourth shaft 22. Therefore, the seat body 10 is swingable in the front-to-rear direction.

FIG. 2 shows the cross-section cut along II-II in FIG. 1. The lateral cross-sectional surfaces of the front leg 30 and the rear leg 40 are formed nearly in U-shapes. The front leg 30 and the rear leg 40 are disposed in such a manner that opening portions of the U-shapes face and loosely fit with each other.

Referring again to FIG. 1, in a space surrounded by the front leg 30 and the rear leg 40, a gas spring 50 that urges the seat body 10 forward, and a link arm 52 are provided.

The gas spring 50 can be compressed by applying external force. When the external force compresses the gas spring 50, the gas spring 50 is provided with constant repulsive force in a stretching direction opposite to the compressing direction. This repulsive force is generated by fluid (gas) sealed inside of the gas spring 50. Depending on pressure and other factors of the gas sealed inside, force required for compression, repulsive force to be generated, stretching speed and the like of the gas spring 50 can be determined.

The link arm 52 is connected to one end (upper end) of the gas spring 50 via a first rotational shaft 54 so as to be rotatable with respect to the upper end of the gas spring 50. Moreover, the link arm 52 is connected to the front leg 30 via a second rotational shaft 56, disposed in a position which is a predetermined distance away from the connecting position of the link arm 52 and the upper end of the gas spring 50 (the position of the first rotational shaft 54). The link arm 52 can be rotated around the second rotational shaft 56.

The second rotational shaft 56 is provided with a rotary damper 58, which restricts rotational speed of the link arm 52 when the link arm 52 is rotated with respect to the front leg 30 in a predetermined direction.

The other end (lower end) of the gas spring 50 is connected to the rear leg 40 via a third rotational shaft 60 disposed on the rear leg 40. The gas spring 50 can be rotated around the third rotational shaft 60.

Inside the front leg 30, a stopper block 62 is provided. Depending on the position of the seat body 10, the stopper block 62 comes in contact with, or comes away from the upper end of the gas spring 50 and the link arm 52.

(2) Movement of Chair 1

The seat body 10 of the chair 1 is supported by the front leg 30, the rear leg 40, and the leg support 20 so as to be movable (swingable) in the front-to-rear direction. The change in the state of the seat body 10 caused by the swing movement in the front-to-rear direction is shown in FIGS. 3A-3D. FIG. 3A illustrate a state wherein the seat body 10 is moved rearward (to the right direction in FIG. 3) to a maximum extent (the state wherein the seat body 10 is located in a rear position). FIG. 3D shows a state wherein the seat body 10 is moved forward (to the left direction in FIG. 3) to a maximum extent (a state wherein the seat body 10 is located in a front position). The rear position may be the position of the seat body 10 or the position of the chair 1, when a user is seated on the chair 1. The front position may be the position of the seat body 10 or the position of the chair 1, when nobody is seated on the chair 1 and the chair 1 is moved to the closest proximity to the desk 2.

The position of the seat body 10 may be understood as the position of the center portion (the center in the front-to-rear direction) of the members constituting the seat body 10, or as the position of the entire portion of the seat body 10. In the present embodiment, the center portion of the members constituting the seat body 10 is defined as the position of the seat body 10.

Two drawings are further presented (see FIGS. 3B and 3C) and illustrate the state of the seat body 10 located between the rear position (FIG. 3A) and the front position (FIG. 3D). When the seat body 10 is located in the front side of the seat body 10 shown in FIG. 3B, the seat body 10 can be moved forward by own weight. The position of the seat body 10 or the position of the chair 1 shown in FIG. 3B corresponds to the first reference position according to the present invention. The first reference position can be understood as a border (reference, in other word) between the states whether or not the seat body 10 is moved forward by own weight. In the state shown in FIG. 3C, the forward urging by the gas spring 50 with respect to the seat body 10 has finished. The position of the seat body 10 or the position of the chair 1 shown in FIG. 3C corresponds to the second reference position according to the present invention. The second reference position can be understood as a border (reference, in other word) between the states wherein whether or not the forward urging by the gas spring 50 with respect to the seat body 10 has finished.

Rear positions, first reference positions, second reference positions, and front positions to be referred in variations, which will be explained later, are respectively identical to the rear position, the first reference position, the second reference position, and the front position described above.

When the seat body 10 is located between the rear position (FIG. 3A) and the second reference position (FIG. 3C), the seat body 10 is urged forward by the urging force of the gas spring 50. In this case, unless external force (for example, some force toward a direction opposite to the direction of the urging by the gas spring 50) is applied to the seat body 10, the seat body 10 can be moved at least to the second reference position (FIG. 3C). Moreover, when the seat body 10 is located between the first reference position (FIG. 3B) and the front position (FIG. 3D), the seat body 10 can be moved forward by own weight as described above.

In the manner described above, the seat body 10 can be moved forward: only by the urging force applied by the gas spring 50 between the rear position (FIG. 3A) and the first reference position (FIG. 3B); by the urging force of the gas spring 50 and the own weight between the first reference position (FIG. 3B) and the second reference position (FIG. 3C); and only by the own weight between the second reference position (FIG. 3C) and the front position (FIG. 3D). That is, unless external force (for example, some force urging the seat body 10 rearward) is applied to the seat body 10, the seat body 10 is automatically moved to the front position (FIG. 3D).

The following will describe this movement more in detail.

When the seat body 10 is located in the rear position (FIG. 3A), one end (the upper end) of the gas spring 50 is pressed by the stopper block 62, and the gas spring 50 is in a compressed state. The length of the gas spring 50 in this state is represented by L1, and the angle between the floor surface and the lateral surface of the rear leg 40 is represented by θ1.

In order to keep the seat body 10 in the rear position (FIG. 3A), the gas spring 50 needs to be kept compressed by, for example, a user sitting on the chair 1. When the external load, applied in order to keep the seat body 10 in the state at the rear position (FIG. 3A), is removed by, for example, the user getting up from the chair 1, the gas spring 50 starts extending. The upper end of the gas spring 50 and the link arm 52 press the stopper block 62. The gas spring 50 keeps extending until the seat body 10 passes the first reference position (FIG. 3B) and is moved to the second reference position (FIG. 3C).

The length of the gas spring 50 when the seat body 10 is located at the first reference position (FIG. 3B) is represented by L2, and the angle between the floor surface and the lateral surface of the rear leg 40 is represented by θ2. The length of the gas spring 50 when the seat body 10 is located at the second reference position (FIG. 3C) is represented by L3, and the angle between the floor surface and the lateral surface of the rear leg 40 is represented by θ3. Moreover, when the seat body 10 is located at the front position (FIG. 3D), the angle between the floor surface and the lateral surface of the rear leg 40 is represented by θ4, and the length of the gas spring 50 becomes the same in FIG. 3C and FIG. 3D. That is, the length of the gas spring 50 when the seat body 10 is located at the front position (FIG. 3D) becomes L3. L3 is the length of the gas spring 50 when the gas spring 50 extends to the maximum extent. In other words, the stopper block 62 is not any further pressed by the upper end of the gas spring 50 from the state wherein the seat body 10 is located at the second reference position (FIG. 3C). Therefore, the relation L3>L2>L1, and also the relation θ4>θ3>θ2>θ1 can be true.

Once the seat body 10 is urged by the gas spring 50 and moved to the second reference position (FIG. 3C), the seat body 10 can be moved forward by own weight. From the second reference position (FIG. 3C) to the front position (FIG. 3D), the length of the gas spring 50 does not change, and the link arm 52 is rotated around the first rotational shaft 54 and the second rotational shaft 56. Consequently, the upper end of the gas spring 50 and the link arm 52 come away from the stopper block 62.

The rotary damper 58, provided to the second rotational shaft 56, shows the shock-absorbing effect after the seat body 10 is moved to the second reference position (FIG. 3C). While the gas spring 50 and the link arm 52 are in contact with the stopper block 62, the link arm 52 is displaced so as to maintain the same positional relation with respect to the front leg 30 (see FIGS. 3A-3C), and is not rotated around the second rotational shaft 56.

In other words, while the upper end of the gas spring 50 and the link arm 52 are in contact with the stopper block 62, the rotary damper 58 is disabled. When the upper end of the gas spring 50 and the link arm 52 come away from the stopper block 62, the rotary damper 58 becomes functional.

The rotary damper 58 is constituted so as to show the shock-absorbing effect only when the seat body 10 is moved forward, and not to show the shock-absorbing effect when the seat body 10 is moved rearward. Therefore, the seat body 10 can be moved to the front position (FIG. 3D) at restricted (controlled) speed. On the other hand, when the seat body 10 is moved rearward, the moving speed of the seat body 10 is not restricted by the rotary damper 58.

In order to move the seat body 10 from the front position (FIG. 3D) to the rear position (FIG. 3A), external force that works toward the rear side of the seat body 10 needs to be applied by, for example, manually pushing the seat body 10 rearward. Corresponding to the rearward movement of the seat body 10, the gas spring 50 and the link arm 52 perform reverse movement opposite to the movement when the seat body 10 is moved forward. That is, when the seat body 10 is moved from the front position (FIG. 3D) to the second reference position (FIG. 3C), the gas spring 50 does not extend or contract, but the link arm 52 is rotated. When the seat body 10 is moved from the second reference position (FIG. 3C) to the rear position (FIG. 3A), the upper end of the gas spring 50 contacts with the stopper block 62, and the gas spring 50 is pressed and gradually compressed.

(3) Effect of the Invention

In the chair 1 according to the present embodiment, the gas spring 50 stops urging the seat body 10 when the seat body 10 is moved further from the second reference position (FIG. 3C) toward the front position (FIG. 3D). Therefore, the shock that can be generated when the seat body 10 is moved to the front position (FIG. 3D) can be reduced.

Moreover, the rotary damper 58 restricts the moving speed of the seat body 10 when the seat body 10 is moved beyond the second reference position (FIG. 3C) toward the front position (FIG. 3D). Therefore, the shock that can be generated at the front position (FIG. 3D) can be further reduced. In addition, the rotary damper 58 does not restrict the moving speed of the seat body 10, until the seat body 10 is moved beyond the second reference position (FIG. 3C) toward the front position (FIG. 3D). Therefore, the seat body 10 can be smoothly moved to the front position (FIG. 3D).

Furthermore, in the chair 1, when the seat body 10 is located at the front position (FIG. 3D), the urging force of the gas spring 50 is not exerted. In addition, the rotary damper 58 does not reduce the moving speed when the seat body 10 is moved rearward. Thus, when the seat body 10 is moved from the front position (FIG. 3D) to the rear position (FIG. 3A) by, for example, manually pushing the seat body 10 rearward, the seat body 10 does not receive reaction force from the gas spring 50 and the rotary damper 58 at the front position (FIG. 3D). As a result, the force required to start the rearward movement of the seat body 10 becomes small, and the seat body 10 can be smoothly moved rearward.

(4) Corresponding Relations

The front leg 30 and the rear leg 40 correspond to one example of the swing portion according to the present invention. One end (the upper end) of the gas spring 50 corresponds to one example of the pressing portion according to the present invention.

[Variation]

The above explained an embodiment of the present invention. However, it should be understood that the present invention is not limited to the above-described embodiment, and can be carried out in various ways within the technical scope of the present invention.

For example, in the above-described embodiment, one exemplary structure is presented wherein the upper end of the gas spring 50 and the link arm 52 both contact with the stopper block 62. An alternative structure may be adopted wherein only one of the upper end of the gas spring 50 and the link arm 52 contacts with the stopper block 62.

Moreover, a structure without using the link arm 52 may be also possible. However, since the link arm 52 works so as also to restrict the movable range of the gas spring 50 by being connected to the upper end of the gas spring 50, restricting the movement of the gas spring 50 corresponding to the movement of the seat body 10 becomes difficult, if the link arm 52 is simply removed from the chair 1 according to the embodiment. Therefore, in the alternative structure, the movable range of the upper end of the gas spring 50 should be preferably controlled. For example, a structure as shown in FIGS. 4A and 4B may be adopted wherein an elongate hole 64 is formed on the front leg 30, and an engaging piece 68, provided on one end of a gas spring 66, is engaged with the elongate hole 64 so as to be slidable in the elongate hole 64.

FIG. 4A shows a state wherein the seat body 10 is located at a rear position. FIG. 4B shows a state wherein the seat body 10 is located at a front position. The other end (lower end) of the gas spring 66 may be connected to the rear leg 40 as shown in FIGS. 4A and 4B, or may alternatively be connected to a constituent other than the rear leg 40. The gas spring 66 only needs to be attached so as to be rotatable around a rotational shaft disposed in a position in which the distance from a predetermined position in the elongate hole 64 changes corresponding to the movement of the seat body 10 (for example, the wall surface of the upper end of the elongate hole 64 (see FIG. 4A) on which the engaging piece 68 abuts when the gas spring 66 extends, or the center point of the elongate hole 64, and so on). In the case of FIGS. 4A and 4B, the position in which the other end (lower end) of the gas spring 66 is connected may be arbitrary decided except on the front leg 30. The other end (lower end) of the gas spring 66 may be attached to, for example, the leg support 20.

In a case wherein the elongate hole 64 is provided as described above, the elongate hole 64 may be formed in such a manner that the front leg 30 is pressed by the engaging piece 68 contacting with an end portion of the elongate hole 64 as shown in FIG. 4A. That is, the end portion of the elongate hole 64 may be an alternative to the stopper block 62.

In the above-described embodiment, the structure is explained as an example wherein the gas spring 50 is used as the urging device that urges the seat body 10 forward. However, the urging device is not limited to a gas spring, but various components may be alternatively used. Moreover, the urging device may be attached in various positions.

A coil spring may be used as an urging device other than a gas spring. Moreover, in the above-described embodiment, a gas spring, which is extended by reactive force when the spring is compressed by applying external force, is used as an example. Alternatively, a gas spring which contracts by reactive force when the spring is extended by applying external force, may be used.

The disposition of a gas spring is not limited to the position in the above-described structure, wherein one end (upper end) of the gas spring 50 is connected to the front leg 30 via the link arm 52 and the other end (lower end) of the gas spring 50 is connected to the rear leg 40. One end and the other end of a gas spring may be respectively connected at various positions, for example, at any two points between which a distance to each other (the distance between the two points) changes corresponding to the movement of the seat body 10.

For example, in a case wherein the front leg 30 corresponds to the swing portion according to the present invention, rotational shafts may be provided respectively to the front leg 30 and the seat body 10 (or the seat support 13 instead of the seat body 10), and a gas spring may be attached so as to connect the rotational shafts. The same applies to a case wherein the front leg 30 and the rear leg 40 correspond to the swing portion according to the present invention.

In a case wherein the front leg 30 and the leg receiver 20 correspond to the swing portion according to the present invention, rotational shafts may be provided respectively to the rear leg 40 and the seat body 10 (or the seat support 13 instead of the seat body 10), and a gas spring may be attached so as to connect the rotational shafts. The same applies to a case wherein the rear leg 40 corresponds to the swinging portion according to the present invention.

In a case wherein the front leg 30 and the rear leg 40 correspond to the swing portion according to the present invention, rotational shafts may be provided respectively to the rear leg 40 and the seat body 10 (the seat support 13), and a gas spring may be attached so as to connect the rotational shafts. The rear leg 40 and the seat body 10 (the seat support 13), or the rear leg 40 and the leg receiver 20 may be respectively provided with rotational shafts, and a gas spring may be attached so as to connect the rotational shafts.

In the above-described embodiment, a structure is explained as an example, wherein the moving speed of the seat body 10 is restricted by the rotary damper 58 provided on the second rotational shaft 56. However, the rotary damper 58 may be disposed somewhere else other than on the second rotational shaft 56. For example, the rotary damper 58 may be disposed in the position of the first rotational shaft 54. Alternatively, other shock-absorbing device may be used instead of the rotary damper 58.

Moreover, in the above-described embodiment, a structure is explained as an example, wherein the rotary damper 58 shows the shock-absorbing effect between the second reference position (FIG. 3C) and the front position (FIG. 3D). However, the structure may be such that the shock-absorbing effect is shown when the seat body 10 is located at some other positions, for example, in the entire area between the rear position (FIG. 3A) and the front position (FIG. 3D).

Various components may be used as the support device that supports the seat body 10. In the above-described embodiment, a structure is explained as an example wherein the seat body 10 is supported by two legs: the front leg 30 and the rear leg 40. Alternatively, the seat body 10 may be supported by, for example, one leg. A chair 84, having a seat body 82 supported by one leg 80, is shown in FIGS. 5A-5C. The seat body 82 is provided with a seating surface 81 and a backrest 83. FIG. 5A shows a state wherein the seat body 82 is located in a rear position. FIG. 5B shows a state wherein the seat body 82 is located at a second reference position. FIG. 5C shows a state wherein the seat body 82 is located at a front position. It is to be noted that a first reference position exists between the rear position (FIG. 5A) and the second reference position (FIG. 5B).

In the chair 84, an upper end of a leg 80 is fixed to the seat body 82. A lower end of the leg 80 is pivotally supported by a leg support 86. Inside of the leg 80 is configured in a hollow state. Moreover, inside the leg 80, a stopper block 88 and the gas spring 90 are disposed. One end (upper end) of the gas spring 90 is connected to the leg 80 via a link arm 92, and the other end (lower end) of the gas spring 90 is connected to the leg support 86. A shock-absorbing device, such as a rotary damper, may be provided.

In the chair 84 shown in FIGS. 5A-5C, the movement of the seat body 82 is different from the movement of the seat body 10 of the chair 1 shown in the above-described embodiment (FIGS. 3A-3D). On the other hand, in the chair 84, the same mechanism and effect as in the chair 1 can be achieved.

Moreover, a chair according to the present invention may be constituted as a chair 100 shown in FIGS. 6A and 6B. The chair 100 includes a seat body 110 which is provided with a seating surface 111 and a backrest 112. In the chair 100, a front leg 102 may be fixed so as not to swing, and a rear leg 104 may be configured so as to swingable. In the example shown in FIGS. 6A and 6B, the front leg 102 is fixed almost in an upright standing state. FIG. 6A shows a state wherein the seat body 110 (or the chair 100) is disposed at a rear position, while FIG. 6B shows a state wherein the seat body 110 (or the chair 100) is disposed at a rear position. A first and a second reference positions exist between the rear position (FIG. 6A) and the front position (FIG. 6B).

In the chair 100, a seat support 106 is provided with an elongate hole 108 that engages with a shaft 102a disposed in the upper end side of the front leg 102. Corresponding to the movement of the seat body 110, the shaft 102a of the front leg 102 is relatively moved (slided) inside the elongate hole 108. It is to be noted that an urging device may be provided so as to urge the seat body 110 from the rear position to the second reference position. Moreover, a shock-absorbing device may be provided so as to restrict the moving speed of the seat body 110.

Furthermore, a chair according to the present invention may be constituted as a chair 120 shown in FIGS. 7A and 7B. FIG. 7A shows a state wherein a seat body 122 (or the chair 120) is disposed in a rear position, while FIG. 7B shows a state wherein the seat body 122 (or the chair 120) is disposed in a front position. A first and a second reference positions exist between the rear position (FIG. 7A) and the front position (FIG. 7B).

The chair 120 includes the seat body 122 which is provided with a seating surface 123 and a backrest 124. The chair 120 may be configured in such a manner that the seat body 122 is slidable in the front-to-rear direction on a supporting base 124.

Specifically, a bracket 125 is provided on a back surface of the seat body 122. To the bracket 125, slide shafts 125a and 125b are secured.

On the supporting base 124, an elongate hole 130 is formed. The elongate hole 130 includes a horizontal portion 131 extending almost horizontally, and an inclined portion 132 slanted so as to drop forward.

The slide shafts 125a and 125b engage with the elongate hole 130 so as to be slidable inside the elongate hole 130. As the slide shafts 125a and 125b slide inside the elongate hole 130, the seat body 122 can be moved in the front-to-rear direction. Due to the inclined portion 132 of the elongate hole 130, the front end of the seat body 122 slants downward in the front position.

It is to be noted that, in FIGS. 7A and 7B, an urging device may be provided so as to urge the seat body 122 forward up to the first reference position where the seat body 122 becomes capable of moving forward by own weight. Moreover, a shock-absorbing device may be provided in order to restrict the moving speed of the seat body 122.

A support device that support the seat body 122 may be disposed on somewhere else other than a floor surface, for example, on a wall surface, desk, and so on.

Although the above-described embodiment explained a structure as an example wherein the stopper block 62 comes in contact with the gas spring 50 and the link arm 52, a structure without using the stopper block 62 may be adopted. One example of a chair constituted in such a manner is illustrated in FIGS. 8A-8D.

The positions of a chair 130 are shown in the drawings, in the same manner as the chair 1 illustrated in FIGS. 3A-3D, in which FIG. 8A shows a rear position, and FIG. 8D shows a front position. Between the above-mentioned rear position (FIG. 8A) and the front position (FIG. 8D), a first reference position (FIG. 8B) and a second reference position (FIG. 8C) are respectively determined from the rear side.

Since the chair 130 is not provided with a stopper block, the mechanism so as to compress the gas spring 50 is different from the mechanism of the chair 1.

The lower end 50b (see FIG. 8A) of the gas spring 50 is connected to the third rotational shaft 60, whereas the upper end 50a (see FIG. 8A) is connected to the link arm 52 so as to be connected to the rotational shaft 56 via the link arm 52. Therefore, when the distance between the second rotational shaft 56 and the third rotational shaft 60 (alternatively, to be simply referred to as the above-described distance) is shortened by a predetermined value or larger, the gas spring 50 is rendered in the compressed state.

The above-described distance changes depending on the position of the seat body 10. When the seat body 10 is located at the rear position (FIG. 8A), the above-described distance becomes the shortest. The above-described distance becomes longer in the following order: when the seat body 10 is located at the first reference position (FIG. 8B); at second reference position (FIG. 8C); and at the front position (FIG. 8D). That is, when the seat body 10 is located at the rear position (FIG. 8A), the gas spring 50 is in the most compressed state. When a seated person (a user) gets up, for example, and external load so as to keep the seat body 10 at the rear position (FIG. 8A) is removed, the gas spring 50 extends, renders the above-described distance longer, and, as a result, urges the seat body 10 toward the first reference position (FIG. 8B). The gas spring 50 keeps extending until the seat body 10 passes the first reference position (FIG. 8B) and reaches the second reference position (FIG. 8C). The length of the extended gas spring 50 becomes L3′>L2′>L1′.

When the seat body 10 is urged by the gas spring 50 and moved to the second reference position (FIG. 8C), the seat body 10 is moved forward by own weight. Consequently, the above-described distance becomes longer, but the length of the gas spring 50 does not change any more. Alternatively, the link arm 52 is rotated around the first and the second rotational shafts 54, 56 so as to follow the change in the above-described distance. During this movement, the rotary damper 58 shows the shock-absorbing effect.

In order to move the seat body 10 from the front position (FIG. 8D) to the rear position (FIG. 8A), external force needs to be applied to the seat body 10 by, for example, manually pulling (or putting) the seat body 10 rearward, in the same manner as the chair 1. As described above, the chair 130 can perform the same movement as the chair 1 shown in FIGS. 3A-3D.

Although a specific embodiment has been illustrated and described herein, it is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiment and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention includes any other applications in which the above structures are used. Accordingly, the scope of the invention should only be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

Claims

1. A chair comprising:

a seat body having a seating surface which provides seating to a user;

a support device that supports the seat body such that the seat body is movable along a front-to-rear direction of the chair within a predetermined range; and

an urging device,

wherein, when the seat body is located in an area between a front position, which is a limit in a front side of the predetermined range, and a first reference position, located behind the front position, the support device supports the seat body such that the seat body is moved to the front position by own weight, and

wherein, when the seat body is located between a rear position, which is a limit in a rear side of the predetermined range, and a second reference position located between the first reference position and the front position, the urging device urges the seat body toward the front position, whereas, when the seat body is located between the second reference position and the front position, the urging device does not urge the seat body.

2. The chair according to claim 1,

wherein the urging device comprises a pressing portion that comes in contact with and comes away from one of the seat body and a predetermined surface of the support device, and

wherein, when the seat body is located between the rear position and the second reference position, the pressing portion comes in contact with the predetermined surface and presses the predetermined surface so as to urge the seat body toward the front position, and when the seat body is located between the second reference position and the front position, the pressing portion comes away from the predetermined surface so as not to urge the seat body.

3. The chair according to claim 1 further comprising a shock-absorbing device that restricts moving speed of the seat body toward the front position.

4. The chair according to claim 3, wherein the shock-absorbing device restricts the moving speed of the seat body toward the front position, only when the seat body is located in an area between the second reference position and the front position.

5. The chair according to claim 1, wherein the support device comprises:

a leg support installed on a floor surface; and

a swing portion that supports the seat body and has one end thereof connected to the leg support so as to be swingable in the front-to-rear direction around where the one end is connected.

6. The chair according to claim 1, wherein the urging device is a gas spring.

7. The chair according to claim 1,

wherein the urging device is a gas spring,

wherein the support device comprises: a leg support installed on a floor surface; and a swing portion that supports the seat body and has one end thereof connected to the leg support so as to be swingable in the front-to-rear direction around where the one end is connected,

wherein the chair further comprises a link arm having: one end connected to one end of the gas spring via a first rotational shaft so as to be rotatable around the first rotational shaft; and another end connected to the swing portion via a second rotational shaft, disposed at a distance from the first rotational shaft, so as to be rotatable around the second rotational shaft,

wherein another end of the gas spring is connected to a third rotational shaft, disposed in a position in which a distance from the second rotational shaft changes corresponding to movement of the seat body, so as to be rotatable around the third rotational shaft, and

wherein the gas spring urges the seat body to the front position by one of ways of extending and being compressed, when the seat body is located between the second reference position and the rear position.

8. The chair according to claim 7 further comprising a rotary damper disposed on at least one of the first and the second rotational shafts so as to restrict moving speed of the seat body toward the front position.

9. The chair according to claim 7, wherein the swing portion comprises an abutment surface pressed by one of the gas spring and the link arm, when the gas spring extends.

10. The chair according to claim 1,

wherein the urging device is a gas spring,

wherein the support device comprises: a leg support installed on a floor surface; and a swing portion having one end thereof connected to the leg support and another end thereof connected to the seat body so as to be swingable around the leg support, and

wherein one end of the gas spring is engaged with an elongate hole, formed on the swing portion, so as to be slidable in the elongate hole, and another end of the gas spring is attached to a rotational shaft, disposed in a position in which a distance from the elongate hole changes corresponding to movement of the seat body, so as to be rotatable around the rotational shaft.