Method for inclining a chair seat and chair having an inclinable seat

The disclosure relates to a method for inclining a chair seat and a chair having an inclinable seat for which maintenance can be easily carried out from outside the attaching frame of a chair, wherein the attaching frame is applicable to leg portions of various kinds of chairs. According to the method and the chair for inclining a backrest side of a seat by causing the backrest to be inclined rearwardly, the structure is such that by rearwardly inclining the backrest attached to a backrest attaching member pivotally supported so as to be inclined rearwardly at one side of an attaching frame opened downward and including a top plate 18 and side plates fixed at the upper end of a leg portion, a tip end protruding part of the backrest attaching member is caused to protrude above the attaching frame and is brought into contact with and pushes up the rear, backrest side of a seat receiving plate which is pressed toward said attaching frame and is inclinably attached to a front end of the attaching frame. In this manner, the backrest side of the seat attached to the seat receiving plate is inclined upward.

BACKGROUND OF THE INVENTION 
The present invention relates to a method for inclining a chair seat, by 
which the backrest side of a seat is upwardly inclined when being seated, 
and to a chair having an inclinable seat. 
Conventionally, a method for inclining a chair seat and a chair having an 
inclinable seat, which are disclosed in U.S. Pat. No. 5,605,376 (Feb. 25, 
1997) previously filed by the present applicant, have been known as an 
example of this kind of a chair seat. 
This example is such that a backrest attaching member is pivotally 
supported so as to be inclined at one side of the attaching frame opened 
upward and consisting of a bottom plate and side plates and is pressed to 
the bottom plate side of the attaching frame, wherein a seat receiving 
plate is inclinably pivotally supported at the other side of the attaching 
frame so that the back attached to the backrest attaching member is caused 
to incline rearwardly. Thereby a push-up member existing at the tip end of 
the backrest attaching member causes the seat attached to the seat 
receiving plate to be upwardly inclined along with the seat receiving 
plate. 
In conventional examples, since the attaching frame which is upwardly 
opened is used, in a case where attaching and tightening means such as 
bolts, nuts, screws, pins, etc. of components are loosened or come off, it 
is necessary that the seat is removed from the seat receiving plate and 
the seat receiving plate is further removed from the attaching frame, and 
thereafter the attaching and tightening means are tightened and fixed. 
That is, no maintenance can be carried out from the outside of the 
attaching frame, that is, as it is assembled. This would cause a problem 
in maintenance. 
Furthermore, a taper bushing or a straight bushing is welded to the 
attaching frame and is fixed there for fixing the tip end of the 
supporting column of the chair leg to the attaching frame. That is, this 
fixing member can meet the leg of only one kind of chair. It is impossible 
to replace the fixing member attached and fixed at the attaching frame, 
and it is impossible to meet the legs of various kinds of chairs having 
parts and supporting column, the sizes of which are different from each 
other. This would cause another problem. 
SUMMARY OF THE INVENTION AND ADVANTAGES 
In view of the foregoing shortcomings, it is therefore an object of the 
invention to provide a method for inclining a chair seat and chair having 
an inclinable seat, which is applicable to legs of various kinds of chairs 
and for which the maintenance can be easily carried out from outside of 
its attaching frame. 
That is, according to the invention the backrest side of a seat is inclined 
by causing the backrest to be rearwardly inclined. By rearwardly inclining 
the backrest attached to the backrest attaching member pivotally supported 
so as to be rearwardly inclined at one side of the attaching frame opened 
downward and including a top plate and side plates fixed at the upper end 
of the leg portion, the tip end protruding part of the backrest attaching 
member is caused to protrude through the top plate of the attaching frame 
and is brought into contact with and pushes up the rear, backrest side of 
a seat receiving plate pressed toward the top plate side of the attaching 
frame to thereby cause the backrest side of the seat attached to the seat 
receiving plate to be upwardly inclined. As necessary, a fixing member, 
the inner diameter of which corresponds to the leg portion, is detachably 
attached to the fixing portion of the leg portion and to the attaching 
frame. The fixing member can be replaced, in order to enable the attaching 
frame to be attached to a leg portion of various other chairs. 
A chair according to the invention is such that the backrest side of the 
seat is upwardly inclined by causing the backrest to be inclined 
rearwardly. An attaching frame opens downward, including a top plate and 
side plates and, is attached to the upper end of a supporting column 
extending from a leg portion, a backrest attaching plate, the tip end of 
which has a protrusion part is pivotally supported at one side of the 
attaching frame so as to be inclinable. A seat receiving plate is attached 
to the top plate at the other side of the attaching frame so as to be 
upwardly inclinable and to be pressed toward the top plate side of the 
attaching frame while the backrest is attached to the backrest attaching 
member and a seat is attached to a seat receiving plate. By causing the 
backrest to be rearwardly inclined, the tip end protrusion part of the 
backrest attaching frame is caused to protrude through an opening of the 
top plate of the attaching frame and is brought into contact with and 
pushes up the rear side of the seat receiving plate. In this manner the 
seat is inclined upwardly. As that as necessary, a fixing member, the 
inner diameter of which corresponds to the leg portion, is attached to the 
fixing portion of the leg portion and to the attaching frame. This fixing 
member can be replaced, in order to enable the attaching frame to be 
attached to a leg portion of various other chairs. 
With a method for inclining a chair seat and chair having an inclinable 
seat according to the invention, in a case where a fixing means such as 
bolts, nuts, screws, pins, etc., of the respective components are loosened 
or come off, it is possible to easily carry out maintenance from the 
outside (downward) of the attaching frame as they are assembled, without 
removing the seat receiving plate from the attaching frame since the 
attaching frame to which a seat inclining means is internally provided is 
opened downward. 
Furthermore, since a seat inclining mechanism is of a simple structure 
consisting of an attaching frame, a seat receiving plate pressed toward 
the attaching frame side, and a backrest attaching member, the number of 
steps of production can be decreased, and the production time can be 
shortened, whereby the production cost can be remarkably decreased. 
Further more, since the backrest of the seat is upwardly inclined in line 
with a rearward inclination of the backrest, the backbone of a person 
being seated is straightened and elongated and the heels of the person are 
not caused to float above the floor level. Therefore, the calves can be 
freed from any strain and the load of a person being seated can be 
dispersed to the entirety of the rear side of the femoral region. 
Therefore, a sense of pressure at the rear side of the femoral region in 
the vicinity of the knees can be cancelled to cause the circulation of the 
blood to be much improved and sensitivity to the cold to be eliminated. 
Since a fixing member, the inner diameter of which corresponds to the 
supporting column of the leg portion, is detachably attached to the fixing 
portion of the leg portion and attaching frame, only replacement of the 
fixing member causes the attaching frame to be applicable to a leg portion 
of various kinds of chairs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A chair having an inclinable chair seat according to the invention is such 
that a backrest 10 is made rearwardly inclinable. As shown in FIG. 1 
through FIG. 20, the chair is composed as described below. 
A leg portion 12 of the chair used for the invention internally has an 
elevation and lowering mechanism such as a gas spring, a screw mechanism, 
etc. 
An attaching frame 22 opened downward and consisting of a plate-like top 
plate 18 on which an opening 16 is formed, and plate-like side plates 20 
attached onto the upper end of a supporting column 14 extending from the 
leg portion 12. 
A protrusion portion 36 at the tip end of a backrest attaching member 38 is 
caused to protrude through the opening 16 of the top plate 18 and is 
brought into contact with the rear side of a seat receiving plate 42. The 
protrusion portion 36 pushes up the seat receiving plate 42 to thereby 
Cause a seat 52 attached to the seat receiving plate 42 to be upwardly 
inclined. A guide piece 50 secured at the seat receiving plate 42, which 
is used for guiding the seat receiving plate when inclining the same 
upwards, is inserted into the opening 16 of the top plate 18. 
As shown in FIG. 13 through FIG. 17, a fixing member 34 is such that an 
attaching hole 30 is provided in the vertical direction a second 
cylindrical member 26 of a body 28 consisting of a first cylindrical 
member 24 and the second cylindrical member 26, located below the first 
cylindrical member 26. The diameter of the second cylindrical member 26 is 
larger than that of the first cylindrical member 24, and a removing hole 
32 is drilled in the vertical direction of the connection part connecting 
the first cylindrical member 24 with the second cylindrical member 26. The 
fixing member 34 is attached to the fixing potion of the leg portion 12 
and attaching frame 22. 
In this example, in a case where the fixing member 34 is attached to the 
attaching frame 22, a screw 31 is inserted into the attaching hole 30, and 
the attaching frame is screwed therein. In a case where the fixing member 
34 is removed from the attaching frame 22, after the screw 31 is removed 
from the attaching frame 22, the screw 31 is screwed in the removing screw 
hole 32 of the fixing member 34, whereby the fixing member 34 inserted 
into and fitted to the attaching frame 22 is spaced and removed from the 
attaching frame 22. 
By replacing this fixing member 34, it is possible to apply the attaching 
frame 22 to the leg portion 12 of various kinds of chairs even though the 
diameters of the supporting column 14 of the leg portion 12 are different. 
That is, if a plurality of fixing members having different inner diameters 
are prepared, it is possible to apply the attaching frame 22 to a leg 
portion 12 of a number of chairs (See FIG. 17). 
The backrest attaching member 38 having the protrusion portion 36 formed at 
its tip end is pivotally supported at one side of the attaching frame 22 
so as to be inclinable rearwardly. 
In this example, the backrest attaching member 38 is roughly L-shaped, and 
a supporting pin 40 is used to pivotally support the backrest attaching 
member 38 on the attaching frame 22. 
The seat attaching plate 42 is attached onto the top plate 18 at the other 
side of the attaching frame 22 and simultaneously is pressed toward the 
top plate 18 side of the attaching frame 22. 
In this example, the seat receiving plate 42 is attached to the top plate 
18 of the attaching frame 22 by causing an L-shaped engaging piece 46, 
which protrudes to the rear side of the seat receiving plate 42, to be 
fixed in a slit-like engaging hole 44 formed in the top plate 18. 
By the attaching means, the clearance between the upper surface of one side 
of the attaching frame 22 and the rear side at one side of the seat 
receiving plate 42 is minimized, whereby the inclination distance (height) 
from the top plate 18 of the attaching frame 22 to the seat receiving 
plate 42 can be controlled so as to be decreased. 
Furthermore, by causing the rear side at one side of the seat receiving 
plate 42 to be brought into contact with the upper surface of one side of 
the attaching frame 22, the upward inclination of the seat receiving plate 
42 is caused to stop, whereby the seat receiving plate 42 is prevented 
from further upward inclination. 
In this example, a means for pressing the seat receiving plate 42 toward 
the top plate 18 side of the attaching frame 22 is a coil spring 48. 
Furthermore, A guide piece 50 is caused to protrude downward at a position 
corresponding to the opening 16 of the top plate 18 of the attaching frame 
22 of the seat receiving plate 42. 
A backrest 10 is attached to the backrest attaching member 38, and a seat 
52 is attached to the seat receiving plate 42. 
Still furthermore, in the drawings, 54 is a supporting bolt, 56 is a fixing 
nut, 58 is a cap, 60 is an elevating and lowering lever, and 62 is a lever 
knob. 
A description will be given of a method for inclining a chair seat 
according to this example. 
By causing the backrest 10 to be rearwardly inclined against a pressing 
force (resiliency of the coil spring 48) acting toward the top plate 18 
side of the attaching frame 22 of the seat receiving plate 42, the 
protrusion part 36 at the tip end of the backrest attaching member 38 
protrudes through the opening 16 of the top plate 18 of the attaching 
frame by the lever principle, and the protrusion portion 36 at the top end 
of the backrest attaching member 38 is brought into contact with and 
pushes up the rear side of the seat receiving member 42 at the backrest 10 
side. In this manner the seat receiving member 42 and seat 52 are upwardly 
inclined about 3 degrees (the angle considered to be the most suitable) 
with the axial supporting part of the attaching frame 22 made a fulcrum, 
and the angle of the back becomes a conventional 8 to 10 degrees, thereby 
further improving a seating comfort of a person being seated with his back 
fitted to the backrest. 
Furthermore, since the seat receiving plate 42 is pressed toward the top 
plate 18 side of the attaching frame 22 when the backrest 10 is rearwardly 
inclined, the protrusion portion 36 at the tip end of the backrest 
attaching member 38 to which the backrest 10 is attached is pressed to the 
attaching frame 22 side, wherein the backrest 10 is pressed forward, and 
the heavier the weight of a person being seated is, the stronger the 
resiliency, which results from a forward pressing of the backrest 10. 
Thereby, the operating force (load of the back) of the backrest against 
the back of a person being seated is increased, and the lighter the weight 
of a person being seated is, the less the resiliency operates to cause the 
operating force (the load of the back) of the backrest against the back of 
a person being seated to be decreased. Therefore, since the operating 
force of the backrest against the back of a person being seated fixedly 
operates in response to the weight of a person being seated, he will never 
feel that the backrest is too soft or too hard. Accordingly, the seating 
comfort is remarkably improved. 
Therefore, since the backbone of a person being seated can be straightened 
and elongated and the person's heel is not caused to float above the floor 
level, the calves can be freed from any strain and the load of a person 
being seated can be dispersed to the entirety of the rear side of the 
femoral region. Therefore, a sense of pressure at the rear side of the 
femoral region in the vicinity of the knees can be cancelled to cause the 
circulation of the blood to be much improved and sensitivity to the cold 
to be eliminated. 
Still furthermore, in this example, a pivotal supporting means of the seat 
receiving plate 42 and attaching frame 22 is such that an L-shaped 
engaging piece 46 projecting from the rear side at one side of the seat 
receiving plate 42 is engaged in a slit-like engaging hole 44 secured at 
the top plate 18 of the attaching frame 22. However, a pin may be employed 
instead thereof, and other pivotally supporting means by which the seat 
receiving plate 42 is inclinable upwards with respect to the attaching 
frame 22 may also be employed. 
Still furthermore, a seat rear cover may be freely attached downward of the 
outside of the attaching frame 22.