U.S. patent application number 12/003791 was filed with the patent office on 2011-03-31 for chair.
Invention is credited to Isao Okamoto.
Application Number | 20110074197 12/003791 |
Document ID | / |
Family ID | 39278147 |
Filed Date | 2011-03-31 |
United States Patent
Application |
20110074197 |
Kind Code |
A1 |
Okamoto; Isao |
March 31, 2011 |
Chair
Abstract
A chair structure results in a proper counter force when an
occupant reclines on a back. The chair is composed of a pintle, a
base which is supported by the pintle, a back support which is
installed on the back, a seat support which is installed on a seat,
a first swaying pivot, a second swaying pivot which is located in
front of the first swaying pivot, a third swaying pivot which is
located between the first swaying pivot and the second swaying
pivot, and a sliding structure. The chair is provided with simple
structures, and can result in a constant counter force or maintain
a proper counter force depending on an angle of the back, when the
occupant reclines on the back.
Inventors: |
Okamoto; Isao; (Taishan
Township, TW) |
Family ID: |
39278147 |
Appl. No.: |
12/003791 |
Filed: |
December 31, 2007 |
Current U.S.
Class: |
297/300.6 ;
297/340 |
Current CPC
Class: |
A47C 1/03272 20130101;
A47C 1/03294 20130101; A47C 1/03238 20130101; A47C 1/03266
20130101; A47C 3/30 20130101; A47C 1/03255 20130101 |
Class at
Publication: |
297/300.6 ;
297/340 |
International
Class: |
A47C 1/032 20060101
A47C001/032 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 6, 2007 |
CN |
200720094311.4 |
Claims
1. A chair comprising a pintle; a base, which is supported by the
pintle; a back support, which is installed on a back; a seat
support, which is installed on a seat; a first swaying pivot, which
is located on the base, and is connected with the back support in a
manner that the back support is tilted rearwards; a second swaying
pivot, which is located in front of the first swaying pivot, is at
a same level as that of the first swaying pivot, is displaced
upwards or above the first swaying pivot, and connects the seat
support to the base in a manner that the seat support is tilted
upwards and downwards; a third swaying pivot, which is located
between the first swaying pivot and the second swaying pivot, is
displaced at a level higher than that of a connecting line that
connects the first swaying pivot and the second swaying pivot, so
as to connect the back support with the seat support to be tilted
upwards and downwards, and to be linked with rearward tilt of the
back support such that the third swaying pivot raises with the back
support; and a sliding structure, which is linked with rising of
the third swaying pivot, allowing the second swaying pivot to be
guided along a rear upper slant direction.
2. The chair according to claim 1, wherein the sliding structure
guides the second tilting structure in a straight line, or to be
protruded out of an arc at an underside.
3. The chair according to claim 1, wherein the base is provided
with a locking structure to fix the back support.
4. The chair according to claim 2, wherein the base is provided
with a locking structure to fix the back support.
5. The chair according to claim 3, wherein the locking structure is
provided with a swaying unit to fix the back support, a support arm
to sway the swaying unit, and an operating structure to displace
the support arm; on the support arm, and under a condition that
sway of the swaying unit is restricted, when the operating
structure being operated, and an elastic deformation being formed
to absorb a displacement of the sway of the swaying unit for
accumulating energy, thereby enabling the swaying unit to sway.
6. The chair according to claim 4, wherein the locking structure is
provided with a swaying unit to fix the back support, a support arm
to sway the swaying unit, and an operating structure to displace
the support arm; on the support arm, and under a condition that
sway of the swaying unit is restricted, when the operating
structure being operated, and an elastic deformation being formed
to absorb a displacement of the sway of the swaying unit for
accumulating energy, thereby enabling the swaying unit to sway.
Description
BACKGROUND OF THE INVENTION
[0001] a) Field of the Invention
[0002] The present invention relates to a chair, and more
particularly to a chair which is linked to rearward tilt of a chair
back, allowing a chair seat to be raised.
[0003] b) Description of the Prior Art
[0004] In spite that a chair which is linked to rearward tilt of a
chair back for lowering a chair seat is more and more popular, in
terms of a chair which is linked to sway of the chair back and
allows a chair seat to be displaced synchronously, on the contrary,
there is also a chair which is linked to the rearward tilt of the
chair back for raising the chair seat.
[0005] For the chair that is linked to the rearward tilt of the
chair back for raising the chair seat, there is an ergonomic chair
structure disclosed in an international patent publication No. WO
00/74531. As shown in FIG. 36 and FIG. 37, the chair includes the
pintle 101, the base 102 that is supported by the pintle 101, the
back support 104 that is installed on the back 103, the seat
support 106 that is installed on the seat 105, the horizontal pivot
point 107 that is connected on the base 102 to tilt the back
support 104 rearwards, the support arm 108 that is located on the
base 102 to connect the seat support 106, and the horizontal pivot
point 109 that connects the back support extension 112 of the back
support 104 to the seat support 106. After the back 103, which was
put upright as shown in FIG. 36, is tilted rearwards as shown in
FIG. 37, the horizontal pivot point 109 will be raised. Besides,
through the rising of the horizontal pivot point 109, the support
arm 108, which was tilted forwards, can be raised. As a result, the
linkage is generated with the rearward tilt of the back 103,
thereby allowing the seat 105 to be raised.
[0006] In this chair, the force that lowers the seat 105 becomes
the force for putting the back 103 upright. As a result, the weight
of the occupant who sits on the seat 105 will result in the
resistance against the rearward tilt of the back 103. Therefore,
the heavier the occupant is, the larger the force will be needed to
tilt the back 103 rearwards for resulting in the counter force,
which is formed when the back 103 is tilted rearwards, to be fitted
with the weight of the occupant.
[0007] However, there indeed exists following issues and
shortcomings required to be improved, upon using the aforementioned
chair.
[0008] For the conventional chair, when the seat 105 is raised, the
support arm 108 will rotate at the center through the horizontal
pivot point 110 at the underside, to change from the forward tilt
condition to the upright condition, as shown by a curve C in FIG.
27, which is a stage that the support arm 108 starts to be putted
upright. In other words, at the stage that the back starts to be
tilted rearwards, the seat 105 will be changed into the maximum
liftable condition. As shown by the curve C in FIG. 27, in the
process that the occupant tilts the back 103 rearwards, the counter
force at the initial stage of the process will be the largest, and
is then decreased. For this kind of chair, a larger force is
required when the back 103 starts to be tilted; whereas, the
occupant should recline hard on the back 103. Nevertheless, when
the back 103 is tilted to a certain extent, the counter force will
be weakened suddenly, allowing the back 103 to be easily tilted
abruptly. As a result, the counter force is not configured
appropriately.
[0009] On the other hand, as this kind of chair uses the support
arm 108 which connects the front half of the seat support 106 with
the base 102, more parts are required correspondingly. In other
words, the support arm 108 will become the necessary accessory, and
the horizontal pivot points 110, 111 should be also installed on
the support arm 108. Therefore, the parts will be increased,
manufacturing cost will be increased and a more complex structure
will be induced.
SUMMARY OF THE INVENTION
[0010] The primary object of the present invention is to provide a
chair which includes a pintle; a base which is supported by the
aforementioned pintle; a back support which is installed on a back;
a seat support which is installed on a seat; a first swaying pivot
which is located on the aforementioned base to connect with the
aforementioned back support; a second swaying pivot, which is
located in front of the aforementioned first swaying pivot, is at a
same level as that of the first swaying pivot, is displaced upwards
or above the first swaying pivot, and connects the aforementioned
seat support on the base in an upward or downward sway manner; a
third swaying pivot, which is located between the first swaying
pivot and the second swaying pivot, is displaced at a location
higher than a connecting line that connects the first swaying pivot
and the second swaying pivot, such that the aforementioned back is
support and the seat support can be connected to sway upwards and
downwards, and that the third swaying pivot can be linked with
rearward tilt of the back support to raise; and a sliding
structure, which is linked with rising of the aforementioned third
swaying pivot, allowing the second swaying pivot to be guided along
a rear upper slant direction.
[0011] Accordingly, when the back and the back support are tilted
rearwards with the first swaying pivot as a center, a rear side is
swayed immediately. Therefore, the third swaying pivot will be
raised, and the second swaying pivot will be displaced along the
rear upper slant direction, in association with the rising of the
third swaying pivot. As a result, the seat support, which is
supported by the second swaying pivot and the third swaying pivot,
will be raised entirely. Accordingly, weight of an occupant that
operates along a direction for lowering the seat support will
result in a counter force against the rearward tilt of the back.
Under this condition, the second swaying pivot will be guided to
move along the rear upper slant direction by a function of the
sliding structure. Hence, in a stage that the rearward tilt starts,
the seat support will not be raised significantly and then
slightly, and in an initial stage that the back is tilted
rearwards, the rising of the seat support will not be enhanced
quickly, thereby preventing from a condition that an extremely
large counter force occurs suddenly and then diminishes, at the
initial stage that the back is titled rearwards.
[0012] Another object of the present invention is that in a chair
of the present invention, the sliding structure will guide the
second swaying pivot along a straight line, or to be protruded out
of a circular arc at an underside. As a result, when the back
starts to be tilted rearwards, from the initial stage to a final
stage that the back is tilted rearwards; a rising rate of the
second swaying pivot will be equalized, and gradually increased
following the rearward tilt of the back. At this time, if a
rearward tilt angle of the back is increased by .theta., and a
rising distance of the second swaying pivot is assumed to be h,
then the rising rate of the second swaying pivot will be h/.theta..
Therefore, the rising of the seat will be equalized as shown by a
curve A, or be gradually increased as shown by a curve B, upon
tilting the back rearwards. Accordingly, the counter force will be
equalized as shown by the curve A, or be gradually increased as
shown by the curve B.
[0013] Still another object of the present invention is to provide
a locking structure on the base for fixing the back support. As a
result, the back support can be prevented from being tilted
rearwards by an operation of the locking structure, and after the
operation of the locking structure has been released, the back
support can be restored to a condition that it can be tilted
rearwards.
[0014] Yet still another object of the present invention is to
provide a locking structure which is provided with a swaying unit
to fix the back support, a support arm to sway the swaying unit,
and an operating structure to displace the support arm, such that
under a condition that sway of the swaying unit, which is located
on the support arm, is restricted, and when the operating structure
is operated, an elastic deformation is formed to absorb a
displacement of the swaying unit for accumulating energy, thereby
swaying the swaying unit.
[0015] Accordingly, by the operation of the operating structure,
the support arm will sway the swaying unit to fix the back support
or to release the fixing state. In other words, after the locking
structure has started to operate, the rearward tilt of the back
support will be prohibited; or the back support can be tilted
rearwards as the operation of the locking structure is released.
When the back support is titling rearwards, the sway of the swaying
unit is restricted due to the back support. Under this condition,
through controlling the operating structure, an elastic deformation
part which is disposed on the support arm will be deformed
elastically to absorb the displacement of the swaying unit for
accumulating energy, without swaying the swaying unit reluctantly.
Besides, once the back support, which was titled rearwards
originally, is putted upright, the swaying unit can sway.
Therefore, under a condition that the elastic deformation part is
restored to its original shape after being deformed elastically,
the swaying unit will sway.
[0016] To enable a further understanding of the said objectives and
the technological methods of the invention herein, the brief
description of the drawings below is followed by the detailed
description of the preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows a side view of a first embodiment of a chair of
the present invention, wherein a back is not tilted rearwards.
[0018] FIG. 2 shows a side view of a chair of the present
invention, wherein a back is tilted rearwards.
[0019] FIG. 3 shows cutaway views of a base, a back support, and a
seat support of a chair of the present invention, with (A) being a
state that the back support is not tilted rearwards, and (B) being
a state that the back support is titled rearwards.
[0020] FIG. 4 shows a plan view of a back support that is assembled
to a base.
[0021] FIG. 5 shows a cutaway view along a line V-V of FIG. 3, for
describing a height adjustment structure.
[0022] FIG. 6 shows a cutaway view of an enlarged installation part
of an operating rod of a height adjustment structure.
[0023] FIG. 7 shows a side view of a second embodiment of a chair
of the present invention.
[0024] FIG. 8 shows cutaway view of a locking structure of a chair
of the present invention, with (A) being a state that a back
support is not fixed, and (B) being a state that the back support
is fixed.
[0025] FIG. 9 shows a plan view of a locking structure of a chair
of the present invention.
[0026] FIG. 10 shows a turn-over unit of a locking structure of a
chair of the present invention, with (A) being a front view of a
state that a back support is not fixed, and (B) being a front view
of a state that a back support is fixed.
[0027] FIG. 11 shows a cutaway view of a swaying unit of a locking
structure of a chair of the present invention, wherein the swaying
unit is installed on a base.
[0028] FIG. 12 shows a front view of a seat installation part which
is fixed on a back support.
[0029] FIG. 13 shows a front view of an armrest installation part
which is fixed on a seat support.
[0030] FIG. 14 shows a side view of an embodiment, excluding a
sliding structure.
[0031] FIG. 15 shows a side view of an embodiment, excluding a
counter force structure.
[0032] FIG. 16 shows a side view of a counter force structure and
another embodiment.
[0033] FIG. 17 shows a bottom view of a first type of a
representative installation structure of a seat.
[0034] FIG. 18 shows a cutaway view along a line A-A of FIG.
17.
[0035] FIG. 19 shows a cutaway view along a line B-B of FIG.
17.
[0036] FIG. 20 shows a bottom view of a second type of a
representative installation structure of a seat.
[0037] FIG. 21 shows a cutaway view along a line A-A of FIG.
20.
[0038] FIG. 22 shows a bottom view of a third type of a
representative installation structure of a seat.
[0039] FIG. 23 shows a side view of an installation structure of
FIG. 22.
[0040] FIG. 24 shows a front view of an installation structure of
FIG. 22.
[0041] FIG. 25 shows a top view of a fourth type of a
representative installation structure of a seat.
[0042] FIG. 26 shows a cutaway view along a line A-A of FIG.
25.
[0043] FIG. 27 shows a graph of variations between a rearward tilt
angle of a back and a seat height of the prior art.
[0044] FIG. 28 shows a graph of variations between a rearward tilt
angle of a back and a resulted counter force.
[0045] FIG. 29 shows a cutaway view of another embodiment of an
installation structure of an operating rod of a height adjustment
structure.
[0046] FIG. 30 shows a cutaway view of a locking structure and
another embodiment wherein a back support is not fixed.
[0047] FIG. 31 shows a cutaway view of a locking structure wherein
a back support is fixed.
[0048] FIG. 32 shows a plan view of a locking structure.
[0049] FIG. 33 shows a cutaway view along a line X-X of FIG.
32.
[0050] FIG. 34 shows a cutaway view along a line Y-Y of FIG.
33.
[0051] FIG. 35 shows a cutaway view along a line Z-Z of FIG.
33.
[0052] FIG. 36 shows a side view of a conventional chair of the
prior art, wherein a back is not tilted rearwards.
[0053] FIG. 37 shows a side view of a chair of the prior art,
wherein a back is tilted rearwards.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0054] Referring to FIGS. 1 to 6, showing a first embodiment of a
chair of the present invention, a chair is provided with a pintle
1; a base 2, which is supported by the pintle 1; a back support 4,
which is installed on a back 3; a seat support 6, which is
installed on a seat 5; a first swaying pivot 7, which is connected
at the base 2 to tilt the back support 4 rearwards; a second
swaying pivot 8, which is connected at the base 2 to sway the seat
support 6 upwards and downwards; a third swaying pivot 9, which
connects the back support 4 and the seat support 6 to sway the back
support 4 and the seat support 6 upwards and downwards, and which
is linked to rearward tilt of the back support 4, such that the
third swaying pivot 9 can be raised along with the back support 4;
and a sliding structure 10, which is linked to rising of the third
swaying pivot 9 to guide the second swaying pivot 8 along a rear
upper slant direction.
[0055] The base 2 is latched on a top of the pintle 1, and a bottom
plate 2a of the base 2 is provided with a cylinder 2b, a diameter
of which is gradually reduced from bottom to top. In addition, an
interior of the pintle 1 is provided with a pneumatic spring 18 to
adjust height, a top of this pneumatic spring 18 is protruded out
of an upper end of the pintle 1, and a circumference at an upper
part of the pneumatic spring 18 is a slant surface with a diameter
being gradually reduced from bottom to top. As a result, the base 2
can be installed on the top of the pintle 1 by inserting the upper
part of the pneumatic spring 18 into the cylinder 2b from top to
bottom. Rear half parts of left and right side plates 2c, 2b of the
base 2 are provided with through-holes for transfixing with the
first swaying pivot 7, and front half parts are provided with
through-holes for transfixing with the second swaying pivot 8. In
this embodiment, the through-hole of the second swaying pivot 8 is
a long hole to serve as the sliding structure 10. In addition, the
long hole will be described as the sliding structure 10,
hereafter.
[0056] As the seat support 6 supports the seat 5, it can freely
sway and be freely installed slidingly on the base 2. The seat
support 6 is constituted by an upper plate 6a above the base 2, and
a pair of left and right side plates 6b, 6c that are hung down from
two side edges of the upper plate 6a. These parts are formed by
bending a piece of board material. In terms of the seat 5, the seat
5 is installed on the upper plate 6a by screws. In addition, the
left and right side plates 6b, 6c are disposed at exterior sides of
the side plates 2c, 2d of the base 2, and central positions of the
left and right side plates 6b, 6c of the seat support 6 are
provided with through-holes for transfixing with the third swaying
pivot 9, whereas front half parts are provided with through-holes
for transfixing with the second swaying pivot 8.
[0057] The back support 4 is to support the back 3, and hence, the
back support 4 can be installed on the base 2 in a manner that it
can sway freely. The back support 4 is constituted by the side
plates 2c, 2d of the base 2, a pair of left and right side plates
4a, 4b between the side plates 6b, 6c of the seat support 6, and a
support plate 4c between the left and right side plates 4a, 4b. A
front half and a rear half of the support plate 4c are formed with
an elevation difference, with the front half being higher, and the
rear half lower. The rear half of the support plate 4c is loaded
with loadings 4d at the rear halves of the left and right side
plates 4a, 4b, and the loadings 4d are fixed by welding or like. By
this configuration, the loadings 4d will be integrally formed with
the left and right side plates 4a, 4b, as well as the support plate
4c. By welding or like, an installation plate 11 which is fixed on
the back 3 is fixed on the rear half of the support plate 4c by
bolts or like. The front half of the support plate 4c is extended
to a level higher than that of the rear half, and is disposed above
the base 2. Central positions of the left and right side plates 4a,
4b of the back support 4 are provided with through-holes for
transfixing with the first swaying pivot 7, and the front halves
are provided with through-holes for transfixing with the third
swaying pivot 9.
[0058] The first swaying pivot 7 is transfixed into the
through-holes of the base 2, and the through-holes located at the
back support 4, to connect the back support 4 at the base 2, and to
allow the back support 4 to be tilted rearwards. A front end of the
first swaying pivot 7 is latched with a pull preventer 12. The
second swaying pivot 8 is transfixed into the sliding structures 10
of the base 2, and the through-holes located at the seat support 6,
to connect the base 2, such that the seat support 6 can sway
upwards and downwards. A front end of the second swaying pivot 8 is
latched with the pull preventer 12. The third swaying pivot 9 is
transfixed into the through-holes of the seat support 6, and the
through-holes located at the back support 4, to connect the seat
support 6 with the back support 4, allowing the seat support 6 and
the back support 4 to sway. A front end of the third swaying pivot
9 is latched with the pull preventer 12.
[0059] The sliding structure 10, such as the long through-hole
extended linearly along the rear upper slant direction, is latched
with push buttons 13 made by polyacetal at its peripherals,
allowing the second swaying pivot 8 to smoothly slide. An angle of
the sliding structure 10 is preferably toward the rear upper slant
direction, for example, tilting by about 40.degree.-70.degree.,
with the best configuration being tilting along the rear upper
slant direction at about 55.degree.. Moreover, the length of the
sliding structure 10 will be 25 mm under the condition that it is
tilted along the rear upper slant direction at 55.degree., and the
second swaying pivot 8, for example, will be raised by about 20
mm.
[0060] The second swaying pivot 8 is disposed in front of the first
swaying pivot 7, and is at a level higher than that of the first
swaying pivot 7. The second swaying pivot 8, following the
displacement of the third swaying pivot 9, is guided and displaced
to the sliding structure 10, with its range of displacement being
in front of the first swaying pivot 7 and above the first swaying
pivot 7. However, if the second swaying pivot 8 is disposed in
front of the first swaying pivot 7, and is at a same level as that
of the first swaying pivot 7, then it can be also guided from this
position to the sliding structure 10 along the rear upper slant
direction. Besides, even under this condition, the second swaying
pivot 8 will be displaced in front of the first swaying pivot 7.
Moreover, the third swaying pivot 9 is disposed between the first
swaying pivot 7 and the second swaying pivot 8, and is located
above a connecting line L that connects the first swaying pivot 7
and the second swaying pivot 8. The third swaying pivot 9 will be
displaced following with rearward tilt of the back support 4, with
its range of displacement being located between the first swaying
pivot 7 and the second swaying pivot 8, and above the connecting
line L that connects the first swaying pivot 7 and the second
swaying pivot 8.
[0061] On the other hand, when the second swaying pivot 8 is at the
range below the first swaying pivot 7, no displacement will occur.
As a result, the second swaying pivot 8 can be smoothly raised
along with the rearward tilt of the back support 4. Assuming that
the second swaying pivot 8 is disposed below the first swaying
pivot 7, when the third swaying pivot 9 is above the connecting
line L that connects the first swaying pivot 7 and the second
swaying pivot 8, and is below the first swaying pivot 7, the third
swaying pivot 9 will sway toward the rear upper slant direction
with the first swaying pivot 7 as an axis, following with the
rearward tilt of the back support 4. Therefore, a force of forward
operation will be developed on the second swaying pivot 8,
prohibiting the second swaying pivot 8 from sliding toward the rear
upper slant direction, and allowing the range of displacement of
the second swaying pivot 8 to be above the first swaying pivot 7 or
at the same level as that of the first swaying pivot 7, so as to
avoid the aforementioned condition and to enable the second swaying
pivot 8 to be smoothly raised following with the rearward tilt of
the back support 4.
[0062] A counter force structure 14 is disposed between the base 2
and the back support 4. By exerting a force on a top of the back
support 4, the counter force structure 14 will press the back
support 4 to restore to an original position when the back support
4 is tilted rearwards. Referring to FIG. 3, the counter force
structure 14 is constituted by a coil spring 15 and spring plates
16 at two ends of the coil spring 15. The spring plate 16 at an
upper side is folded and latched into a periphery of an axis 17 in
the spring plate 16 at a lower side, and a distance between the
upper side spring plate 16 and the lower side spring plate 16 will
be changed following an extension or compression of the coil spring
15. The lower side spring plate 16 is provided with a concaved part
16a, and the upper side spring plate 16 is provided with a convex
part 16b. By latching the concaved part 16a into a convex part 2g
of the base 2, and inserting the convex part 16b into a concaved
part 4g on the back support 4, the counter force structure 14 can
be installed between the base 2 and the back support 4. The counter
force structure 14 is disposed at a rear side of the first swaying
pivot 7, and once the back support 4 is tilted rearwards, the coil
spring 15 will be compressed, thereby resulting in the counter
force.
[0063] Furthermore, as the pneumatic spring 18, which is used to
adjust the height, has been used very commonly, it will not be
described further. The pneumatic spring 18 operates through a
height adjustment structure 19. The height adjustment structure 19
in this embodiment is composed of an operating rod 20 and an
installation tool 21 which is installed at the base 2 to sway the
operating rod 20. The operating rod 20 includes an operating stick
which is bended into a crank shape, an extension part 20a which is
extended along a breadth direction of the chair for installing an
operating plate 22, an shaft branch 20b which is extended toward a
rear side from the extension part 20a, and an operating part 20c
which is extended toward the breath direction of the chair from a
front end of the shaft branch 20b. The shaft branch 20b and the
operating part 20c are collected in the base 2, and the extension
part 20a is protruded out of an exterior side of the base 2 from a
long through-hole 2h on the right side plate 2c of the base 2. By
two pieces of relieving arches 2i disposed at the base 2, and the
installation tool 21 of the relieving arch 2j which is disposed
between the relieving arches 2i, the shaft branch 20b can be
supported and turned over. In other words, concaved locations of
the two relieving arches 2i, and concaved locations of the
installation tool 21 will clamp the shaft branch 20b from top to
bottom, so as to constitute a bearing. The operating part 20c is
stuffed into the convex part 18a of the pneumatic spring 18 to form
an operable state. The long through-hole 2h of the base 2 forms a
swaying shape for the operating rod 20. As shown by a solid line in
FIG. 5, the operating rod 20 presses down the extension part 20a by
its weight, thereby rising up the operating part 20c.
[0064] Once an occupant has reclined on the back 3, the coil spring
15 of the counter force structure 14 is compressed, and in a mean
time, the back 3 and the back support 4 are tilted rearwards with
the first swaying pivot 7 as a center. As a result, the third
swaying pivot 9 will be raised. In addition, linkage is formed
along with the rising of the third swaying pivot 9, allowing the
second swaying pivot 8 to be guided to the sliding structure 10 and
be displaced along the rear upper slant direction. In other words,
as the second swaying pivot 8 and the third swaying pivot 9 are
raised, the seat support 6 and the seat 5 are raised too. As the
seat is taken by the occupant, and the weight of the occupant
becomes a force to restrain the rising of the seat 5, a force that
tilts the back 3 rearwards will correspondingly become a counter
force.
[0065] A chair, a counter force of which as shown by a curve A or a
curve B in FIG. 28, can almost have an equalized counter force
without a limitation to a rearward tilt angle of the back 3, or can
have a counter force which is gradually increased as the rearward
tilt angle of the back 3 increases. After the occupant has reclined
on the back 3 and tilted the back 3 to a maximum extent, the back 3
will not be easily tilted suddenly, thereby improving
comfortableness while being seated. As a result, it is preferably
to configure the counter force as that of the curve A or B in FIG.
28.
[0066] In the chair of this embodiment, the sliding structure 10
will guide the second swaying pivot 8 toward the rear upper slant
direction in a straight line. In addition, the third swaying pivot
9 will be displaced toward the rear upper slant direction along a
circumference with the first swaying pivot 7 as a center.
Accordingly, a relationship between an increment .theta. of the
rearward tilt angle of the back 3 and a rising distance h of the
second swaying pivot 8 will be constant, and from the back 3 starts
to be tilted rearwards, to an initial stage and to a final stage of
the rearward tilt, all of the rising rates (h/.theta.) of the
second swaying pivot 8 will be equalized. To put it another way,
the positions of the first, second, third swaying pivots 7, 8, 9
and the tilt angle of the sliding structure 10 will equalize the
rising rates (h/.theta.) of the second swaying pivot 8 when the
back support 4 is tilted rearwards. Therefore, as shown by the
curve A in FIG. 27, as the tilt angle of the back support 4
increases, the seat support 6 and the seat 5 will be slowly rising
at a certain distance, and the resulted counter force will become a
constant. As a result, at a moment when the occupant tilts the back
3 rearwards, there will be no large change to the counter force,
and the back 3 can be tilted rearwards continuously with almost the
same force. That is to say, for the chair as shown in FIG. 36, the
back will be easily tilted due to that the counter force is
weakened suddenly, after the back has been tilted to a certain
extent; whereas, for the chair of the present invention, this
condition can be prevented, thereby improving comfortableness in
using the chair.
[0067] Referring to FIGS. 1 to 6, in terms of the positions of
first, second, third swaying pivots 7, 8, 9, and the tilt angle of
the sliding structure 10, when the back support 4 starts to be
tilted rearwards, the rising rate (h/.theta.) of the second swaying
pivot 8 will become equalized. In other words, under a condition
that the back support 4 is not tilted rearwards, the third swaying
pivot 9 is disposed at about 40.degree. in a front upper slant
direction of the first swaying pivot 7, and the second swaying
pivot 8 is disposed at about 7.degree. in a front upper slant
direction of the first swaying pivot 7, if viewing from a side of
the chair. Moreover, viewing from the side of the chair, the third
swaying pivot 9 is disposed at about 10.degree. in a rear upper
slant direction of the second swaying pivot 8. In addition, viewing
from the side of the chair, the sliding structure 10 is tilted
about 55.degree. toward the rear upper slant direction. Under this
condition, once the back support 4 is tilted rearwards, the third
swaying pivot 9 will be displaced to a position within about
60.degree. in the front upper slant direction of the first swaying
pivot 7, and the second swaying pivot 8 will be displaced to a
position within about 15.degree. in the front upper slant direction
of the first swaying pivot 7. However, the relationship among the
positions of first, second, third swaying pivots 7, 8, 9, and the
tilt angle of the sliding structure 10 is not limited to the
aforementioned angles, as long as that when the back support 4 is
tilted rearwards, the rising rate (h/.theta.) of the second swaying
pivot 8 can be equalized.
[0068] On the other hand, once the occupant stops reclining on the
back 3 and gets up, the coil spring 15 of the counter force
structure 14 will be extended, allowing the back support 4 to be
putted up forwards.
[0069] This chair is constituted through the sliding structure 10
to guide the third swaying pivot 9, allowing the chair to be
composed simply, and thereby controlling an increase of
manufacturing cost.
[0070] The adjustment of height of the seat 5 is disclosed
hereafter. As shown by a solid line in FIG. 5, under a condition
that the operating rod 20 is not operated by the occupant, the
operating rod 20 will lower down the extension part 20a by its
weight, thereby raising the operating part 20c. As a result, the
convex part 18a of the pneumatic spring 18 will not operate, its
length cannot be changed, the length of the pintle 1 will remain at
a constant, and the height of the seat 5 will also remain at a
constant.
[0071] Once the occupant puts lifts up the operating plate 22 of
the operating rod 20, the operating rod 20 will sway with the shaft
branch 20b as a center, as shown by a dotted line in FIG. 5. At
this time, the operating part 20c will be pressed down into the
convex part 18a of the pneumatic spring 18. As a result, the length
of the pneumatic spring 18 can be adjusted, and the length of the
pintle 1 can be changed to adjust the height of the seat 5. Next,
after the occupant has released the operating rod 20, the operating
rod 20 will be restored to a non-operating state by its weight.
[0072] A second embodiment of the present invention is described
hereafter. Besides, in this detailed description and drawings, as a
same part is marked by a same numeral, the repeated description
will be omitted. Referring to FIGS. 7 to 13, the base 2 is provided
with a locking structure 23 to fix the back support 4. The locking
structure 23 is provided with a swaying unit 45 to fix the back
support 4, a support arm 46 to sway the swaying unit 45, and an
operating structure 44 to displace the support arm 46. The
operating structure 44, such as a turn-over unit (called the
turn-over unit 44 hereafter) is connected to the support arm 46
which sways and displaces the swaying unit 45. However, the
operating structure is not limited to the turn-over unit 44, and
any structure is acceptable as long as that it enables the support
arm 46 to be displaced forwards and rearwards (omitting the
drawings). In addition, in this embodiment, an operating plate 47
of the turn-over unit 44 is provided.
[0073] The turn-over unit 44 is disposed between the left side
plate 2d and a wall plate 2n of the base 2, is latched into an axis
48, and cannot be turned over correspondingly. A spring 49 which
can press the turn-over unit 44 toward the wall plate 2n is
disposed between the side plate 2d and the turn-over unit 44. The
axis 48 is supported on the side plate 2d of the base 2, and is
protruded outwards from the left side plate 2d, in a manner that it
can turn over freely. The operating plate 47 is installed on the
protruded portion of the axis 48.
[0074] The turn-over unit 44 is provided with an arm 44a and a
brake 44b. Referring to FIG. 8(A) and FIG. 10(A), the turn-over
unit 44 is turned over from an initial position toward a locking
position as shown in FIG. 8(B) and FIG. 10(B). As a result, the
turn-over unit 44 will enable the arm 44a to be folded toward a
tilted surface 51 of the wall plate 2n and to be turned over at a
same time. At this time, the tilted surface 51 will be protruded
toward the side plate 2d from an initial position where the arm 44a
is in touch with and a locking position where the arm 44a is in
touch with, so as to press the turn-over unit 44, compress the
spring 49, and move toward the side plate 2d. The arm 44a is
connected to the support arm 46 which can sway. Once the turn-over
unit 44 is restored to an original position from the locking
position, the brake 44b will find tune the side plate 2d to prevent
the turn-over unit 44 from excessively turning over.
[0075] The swaying unit 45 includes left and right side plates 45a,
45b, and a connection plate 45c that connects the two side plates
45a, 45b. The left and right side plates 45a, 45b are provided with
shafts 45d, concaved parts 2p on the base 2 are inserted with the
shafts 45d, a cover plate 52 is enclosed at a top and is fixed on
the base 2 by screws 53. The swaying unit 45 is installed on the
base 2 in a manner that it can sway with the shafts 45d as centers.
An upper end of the swaying unit 45 is located in front of the
shafts 45d. As a result, when the swaying unit 45 sways at a rear
side, the upper end of the swaying unit 45 will be raised and
latched into a concaved part 4h of the back support 4. Under this
condition, the upper end of the swaying unit 45 will enter into a
range of rearward tilt of the back support 4.
[0076] Referring to FIG. 8(A), under a condition that the turn-over
unit 44 is restored to the initial position, the support arm 46
will pull up the swaying unit 45 toward a front side, and the upper
ends of the side plates 45a, 45b will be moved out from the
concaved part 4h of the back support 4. In other words, as the side
plates 45a, 45b are moved out of the range of rearward tilt of the
back support 4, the back support 4 can be tilted rearwards. To put
it differently, the back 3 will not be locked.
[0077] On the other hand, as shown in FIG. 8(B), once the turn-over
unit 44 has been turned over to the locking position, the support
arm 46 will allow the swaying unit 45 to sway rearwards. As a
result, the upper ends of the side plates 45a, 45b will be latched
into the concaved part 4h of the back support 4. In other words,
the side plates 45a, 45b will enter into the range of rearward tilt
of the back support 4, thereby restricting the rearward tilt of the
back support 4. To put it another way, the back 3 is locked.
[0078] On the other hand, in this embodiment, a support plate 4c of
the back support 4 is divided into a front half 4ca and a rear half
4cb. The front half 4ca is formed by bending a piece of board
material, and the rear half 4cb is integrally formed with the left
and right side plates 4a, 4b. In other words, the rear half 4cb and
the side plates 4a, 4b are formed by bending the board material,
and the front half 4ca is integrally fixed with the left and right
side plates 4a, 4b by welding or like.
[0079] Furthermore, in this embodiment, as shown in FIG. 6 and FIG.
29, the shaft branch 20b of the operating rod 20 of the height
adjustment structure 19 is emplaced in the concaved locations of
the two relieving arches 2i, and at a same time, the location
between the relieving arches 2i is clamped by the plan-shape
installation tool 21 from top to bottom, so as to support the
operating rod 20 in a manner that the operating rod 20 can be
turned over.
[0080] Seat installation parts 37, for example, are fixed by
welding or like on a top of the seat support 6. The seat
installation parts 37 are provided at a front and a rear place. A
seat shell 38 is fixed by the seat installation parts 37, and the
seat 5 is installed on the seat support 6 with screws, for example.
Moreover, on the seat support 6 is provided with armrest
installation parts 39 to install the armrests which are fixed by
welding or like. Besides, as seen by the chair of this embodiment,
the armrests do not need to be installed even there are the armrest
installation parts 39.
[0081] Even that the chair of this embodiment is the same as that
in FIG. 1, when the occupant starts to tilt the back 3 rearwards,
there will be no condition that the counter force will be increased
in the middle of tilting, and the back 3 can be tilted continuously
almost with the same force, thereby increasing comfortableness in
using the chair. Moreover, by using the sliding structure 10 to
guide the third swaying pivot 9, the chair can be constituted
simply, thereby controlling the increase of the manufacturing
cost.
[0082] On the other hand, the aforementioned embodiment is only one
of the proper embodiments of the present invention, and is not the
necessary embodiment of the present invention. As long as they will
not deviate from the features of the present invention, all kinds
of variations can be available within the range.
[0083] For example, in the aforementioned description, although the
sliding structure 10 guides the second swaying pivot 8 along a
straight line, it can also guide non-linearly. As shown in FIG. 14,
the second swaying pivot 8 is guided to an underside in a protruded
arc-shape manner. In other words, the sliding structure 10 of the
base 2 can be also formed as the underside protruded arc-shape
structure. Under this condition; the rising rate (h/q) of the
second swaying pivot 8 will be gradually increased following the
rearward tilt of the back 3. As a result, referring to the curve B
in FIG. 27, the rising of the seat 5 will be gradually enlarged
following the increase of the rearward tilt angle of the back 3.
Therefore, as shown by the curve B in FIG. 28, the resulted counter
force will be gradually enlarged. Even under this condition, when
the occupant reclines on the back 3 to tilt the back 3 rearwards,
he or she can feel comfortable, thereby increasing comfortableness
while being seated. Under this condition, as long as the positions
of first, second, third swaying pivots 7, 8, 9, and the shape and
curvature of the sliding structure 10 can allow the rising rate
(h/q) of the second swaying pivot 8 to be increased gradually when
the back support 4 is tilted rearwards, then there will be no
special limitation.
[0084] Furthermore, in the aforementioned description, if the
counter force structure 14 cannot adjust the intensity of the
resulted counter force, then it is still acceptable as long as that
the intensity of the resulted counter force is adjustable.
Referring to FIG. 15 or FIG. 16, on a top of the bottom plate 2a of
the base 2 is provided with adjustment screws 40. By changing
amounts of protrusion at front ends of the adjustment screws 40, a
pre-stress of the coil spring 15 of the counter force structure 14
is adjusted, and the intensity of the resulted counter force can be
adjusted. This way is acceptable. Under this condition, as shown in
FIG. 15, on a top of a handle 41 is provided with the adjustment
screws 40. Through the handle 41 to turn over and operate, the
amounts of protrusion of the adjustment screws 40 can be adjusted
without stages, or the intensity of the counter force can be
adjusted. On the other hand, as shown in FIG. 16, at a base end of
an operating rod 42 is provided with the adjustment screws 40.
Through a swaying operation of the operating rod 42, the amounts of
protrusion of the adjustment screws 40, or the intensity of the
counter force, can be adjusted in, for example, three stages.
Besides, on the bottom plate 2a of the base 2, a bottom plate 43
with screw through-holes 43a can be fixed by welding or like. The
adjustment screws 40 are latched into the screw through-holes 43a,
and are protruded from the through-holes 2m of the bottom plate 2a
toward the spring plate 16 at the lower side of the counter force
structure 14.
[0085] Moreover, the locking structure 23 can be also a type which
is provided with a spring part in a mechanism and keeps its own
functions. Referring to FIGS. 30 to 35, on the support arm 46, and
under a condition that the sway of the swaying unit 45 is limited,
when the operating structure 44 is operated, an elastic deformation
is formed to absorb and accumulate energy that sways and displaces
the swaying unit 45. At a same time, once the sway of the swaying
unit 45 is possible, an elastic deformation part (or a spring part)
56 can be also designed to develop a function for swaying the
swaying unit 45. In this embodiment, the configuration disposed is
to bend a middle part of the support arm 46 into the U-shape
elastic deformation part 56. Nevertheless, the shape of the elastic
deformation part 56 is not only limited to this shape, as described
hereafter, as long as that the shape can absorb the displacement
energy accumulated to sway the swaying unit 45, and can develop the
swaying energy, then there will be no special limitation.
[0086] In this embodiment, the turn-over unit 44 of the operating
structure is disposed between the left side plate 2d and the wall
plate 2n of the base 2, and is latched into the axis 48 to prohibit
from being turned over. In other words, by inserting the convex
part 48a which is located at the axis 48 into the concaved part 44d
which is located at the through-hole 44c of the turn-over unit 44,
the turn-over unit 44 will be latched into the axis 48 without
being turned over. A fixing part 57 is located between the
turn-over unit 44 and the bottom plate 2a of the base 2, and is
formed by an elastic material, such as resin, which enables the
convex part 57d between the concaved parts 57a, 57b to be pressed
down by installing the through-hole 57c, to latch the convex part
44e at a bottom of the turn-over unit 44 into the concaved part 57a
or 57b of the fixing part 57. In this manner, the turn-over unit 44
will be fixed at the initial position, as shown in FIG. 30, or
fixed at the locking position, as shown in FIG. 31. By pressing
down the concaved part 57d, the convex part 44e of the turn-over
unit 44 can move between the concaved parts 57a and 57b. As a
result, the turn-over unit 44 can be turned over between the
initial position and the locking position. The fixing part 57 is
latched into the concaved part 2t of the bottom plate 2a of the
base 2.
[0087] The arm 44a is disposed on the top of the turn-over unit 44.
The support arm 46 is connected at the place close to the front end
of the arm 44a in a manner that the support arm 46 can sway. The
other end of the support arm 46 is connected at the side plate 45b
of the swaying unit 45, in a manner that the support arm 46 can
sway.
[0088] The axis 48 is inserted into the through-hole 58 on the side
plate 2d of the base 2, and the through-hole 61 on the wall plate
2n, such that an inner end of the axis 48 can be supported by a
wall plate 2w and the operating rod 20 with the installation tool
21 which can sway, in a manner that the axis 48 can be turned over
freely. The axis 48 is provided with a convex part 48b, and the
convex part 48b is inserted into the concaved part 58a of the
through-hole 58 of the side plate 2d, so as to allow the axis 48 to
be turned over by an angle, and to allow the convex part 48b to
move from a side of the concaved part 58a to the other side. In
other words, the turn-over unit 44 will be restricted from being
turned over to the locking position (as shown in FIG. 34) from the
initial position. If the base 2 is made by a metal, then it will
exceed the range of turning over, allowing the force of reluctantly
turning over to be fed into the axis 48, and the through-hole 58 or
the concaved part 58a will still not be expanded, thereby limiting
the turning-over angle of the axis 48. As a result, the turn-over
unit 44 can be prevented from excessively turning over, the swaying
unit 45 can be prevented from excessively swaying, and the
installation part at the inner end of the axis 48 can be prevented
from being loaded.
[0089] As shown in FIG. 35, the inner end of the axis 48 is loaded
on a top of a section 59 of the wall plate 2w. Close to the inner
end of the axis 48 is formed with a trench 48c on which is inserted
with a fixing piece 21a of the installation tool 21 from top. By
this way, the inner end of the axis 48 can be supported through the
wall plate 2w and the installation tool 21, in a manner that the
axis 48 can sway. Moreover, through inserting the fixing piece 21a
into the trench 48c, the axis 48 can be prevented from withdrawing.
The axis 48 is supported by the operating rod 20 with the
installation tool 21, in a manner that the axis 48 can sway, which
can reduce an amount of parts, and can reduce an assembly
engineering, thereby reducing the manufacturing cost.
[0090] The operating handle 60 is fixed at an exterior end of the
axis 48. Holding the operating handle 60 and turning it over, can
turn over the turn-over unit 44. However, if the operating handle
60 is changed into the operating rod (not shown in the drawings)
that is installed at the axis 48, then the turn-over unit 44 can be
operated by the operating rod.
[0091] In this embodiment, a top of the back support 4 is provided
with a convex part 4i, allowing the swaying unit 45 to be located
outside the swaying range under a condition that the back support 4
is not tilted rearwards, and to the swaying unit 45 will be located
outside the swaying range, and enter into the swaying range once
the back support 4 is tilted rearwards.
[0092] Referring to FIG. 30, when the turn-over unit 44 is restored
to the initial position, the support arm 46 will guide the swaying
unit 45 to the front, and the upper ends of the side plates 45a,
45b will be escaped from the concaved parts 4h of the back support
4. Hence, as shown by an arrow T in FIG. 30, the back support 4 can
be tilted rearwards. In other words, the back 3 is not locked.
[0093] On the other hand, as shown in FIG. 31, once the turn-over
unit 44 is turned over to the locking position, the support arm 46
will sway the swaying unit 45 toward the rear side. As a result,
the upper ends of the side plates 45a, 45b will be latched into the
concaved parts 4h of the back support 4. Under this condition, when
the back support 4 is to be tilted rearwards, the back support 4
will be in touch with the swaying unit 45, thereby prohibiting the
back support 4 from being tilted rearwards. In other words, the
back 3 is locked.
[0094] When the turn-over unit 44 is at the initial position, the
swaying unit 45 is pulled back to the front, as shown by the arrow
T in FIG. 30, and the back support 4 is tilted rearwards, the
convex part 4i of the back support 4 will enter into the swaying
range of the swaying unit 45. Under this condition, after the
operating handle 60 is controlled to sway the swaying unit 45
toward the rear side a little, the swaying unit 45 will be in touch
with the convex part 4i, and cannot sway rearwards further. At this
condition, the operating handle 60 is controlled to further turn
over the swaying unit 45, and the elastic deformation part 56 of
the support arm 46 will be deformed elastically, to absorb the
accumulated displacement energy that sways the swaying unit 45. As
a result, under this condition, once the back support 4, which has
been tilted rearwards, is put upright, the convex part 4i will be
escaped from the swaying range of the swaying unit 45, and the
swaying unit 45 can sway rearwards. The elastic deformation part
56, which was deformed elastically, will be restored to its
original shape, and at a same time, develop its accumulated energy
to sway the swaying unit 45 rearwards. Accordingly, under a
condition that the back 3 is not able to be locked, the swaying
unit 45 cannot still sway even by conducting the locking operation.
Therefore, the structures can be prevented from being damaged.
Moreover, even that the swaying unit 45 cannot sway, the operation
that turns over the turn-over unit 44 can be still conducted, and
the swaying unit 45 can sway automatically when it is able to sway.
Hence, one can conduct the operation without needing to care
whether the back support 4 is tilted rearwards. As a result, the
chair can be used more freely.
[0095] Moreover, when the back 3 is locked by using the locking
structure 23 (as shown by a state in FIG. 31), and once the
occupant reclines on the back 3, the swaying unit 45 will sway
rearwards immediately. Under a condition that the upper ends of the
side plates 45a, 45b are latched into the concaved parts 4h of the
back support 4, when the back support 4 is to be tilted rearwards,
the support plate 4c of the back support 4 will be in touch with
the swaying unit 45. As a result, the support plate 4c is changed
into a state of pressing the swaying unit 45 which is not able to
be pulled back to the front. Under this condition, when the
operating handle 60 is controlled to turn over the turn-over unit
44 to the initial position, the elastic deformation part 56 of the
support arm 46 will be deformed elastically to absorb the
accumulated displacement energy that sways the swaying unit 45.
Hence, at this condition, once the occupant stops reclining on the
back 3, the support plate 4c will be escaped from the swaying unit
45, allowing the swaying unit 45 to be pulled back to the front.
Accordingly, the elastic deformation part 56, which was deformed
elastically, will be restored to its original shape, and develop
the accumulated energy to pull back the swaying unit 45 to the
front. Therefore, under a condition that the back 3 is not able to
be released form the locking state, the swaying unit 45 cannot
still sway even by conducting the unlocking operation. As a result,
the structures can be prevented from being damaged. In addition,
even that the swaying unit 45 cannot sway, the operation to turn
over the turn-over unit 44 can be still conducted, and the swaying
unit 45 can sway automatically when it can. Accordingly, one can
conduct the operation without needing to care whether the back
support 4 is tilted rearwards, and the chair can be used more
freely.
[0096] Furthermore, referring to FIGS. 17 to 19, on a seating
accessory of the seat support 6, the seat shell 38 can be also
fixed with screws. In other words, on a top of a concaved position
38a of the seat shell 38 is disposed with the seat support 6, and
screws 54 can be used to fix the seat shell 38 and the seat support
6.
[0097] Moreover, referring to FIG. 20 and FIG. 21, on the seating
accessory of the seat support 6, in addition to that the screws are
used to fix the seat shell 38, armrest installation accessories 39
can be also fixed on the seat support 6 by welding or like. In
other words, the top of concaved position 38a of the seat shell 38
is disposed with the seat support 6, and at a same time when the
screws 54 are used to fix the seat shell 38 and the seat support 6,
the armrest installation accessories 39 can be disposed to install
the armrests.
[0098] Moreover, referring to FIGS. 22 to 24, on the seating
accessory of the seat support 6, the seat installation part 37 can
be also fixed by welding or like; whereas, at a same time, a
seating plate 55 can be fixed at the seat installation part 37 with
screws.
[0099] Moreover, referring to FIG. 25 and FIG. 26, the second
swaying pivot 8 and the third swaying pivot 9 can be also extended,
and the second swaying pivot 8 can be connected with the third
swaying pivot 9 by a seat enhancement accessory of the seat support
6. At a same time, a hook 38b is formed on the seat shell 38, to
hook at the first swaying pivot 8 and the third swaying pivot 9,
thereby assembling the seat shell 38 at the seat support 6.
[0100] The present invention is provided with following advantages:
[0101] 1. At the stage that the back starts to be tilted, the
operation that the seat rises significantly and then rises slightly
can be prevented. As a result, the condition that the back is easy
to be tilted by the quick weakening of the counter force after the
back is tilted from a certain extent can be avoided, thereby
improving the comfortableness in using the chair. Besides, by using
the sliding structure to guide the third swaying pivot, the chair
can be constructed simply to reduce the manufacturing cost. [0102]
2. The sliding structure guides the second swaying pivot in a
straight line or to be protruded out of the circular arc at the
underside. As a result, at the moment that the back is tilted
rearwards, the rising of the seat will be equalized as shown by the
curve A in FIG. 27, or be enlarged gradually as shown by the curve
B in FIG. 27. As a result, almost the equalized counter force can
be acquired disregarding the rearward tilt angle as shown by the
curve A in FIG. 28. On the other hand, as shown by the curve B in
FIG. 28, when the rearward tilt angle of the back increases, the
counter force can be changed. Therefore, when the occupant reclines
on the back to tilt the back rearwards, a constant counter force
can be maintained, or a proper counter force can be maintained
depending on the angle of the back, thereby improving the
comfortableness while being seated. [0103] 3. The chair of the
present invention is provided with the elastic deformation part
that absorbs the relative displacement between the operating
structure and the swaying unit to accumulate as energy. As a
result, when the sway of the swaying unit is restricted, the
swaying unit will not sway reluctantly, thereby preventing the
structures from being damaged. In addition, even that the swaying
unit cannot sway; the operation can be still conducted through the
operating structure. Under the condition that the swaying unit
cannot sway, the operating structure is controlled and when the
swaying unit can sway, it will sway automatically. Therefore, the
operation of the operating structure can be conducted without
needing to care whether the back is tilted rearwards, and the chair
can be used more freely.
[0104] It is of course to be understood that the embodiments
described herein is merely illustrative of the principles of the
invention and that a wide variety of modifications thereto may be
effected by persons skilled in the art without departing from the
spirit and scope of the invention as set forth in the following
claims.
* * * * *