Work Chair
An ergonomic work chair for activities requiring a bent-forward posture has the following features: a supporting cylinder which protrudes from a star base, a supporting column, which is mounted in the supporting cylinder such that it can be displaced in a vertical cylinder axis, for a base plate with a seat which is fixed on the base plate, a base arm which is fitted to the supporting column or to the base plate, and a pivoting arm, which is mounted on the base arm such that it can be rotated out of the seat region about a vertical axis, having a chest rest and side arm rests, and a support which has a star rest and is hinge-connected to the base plate via a lever mechanism which has fulcrums such that pressing down on the seat causes the star rest to move in the direction of the chest rest.
The present invention relates to an ergonomic work chair for the performance of activities in bent-forward posture.
PRIOR ARTIn manual activities which are practiced in seated position with slightly bent-forward posture, such as, for example, in dentistry, the musculature in the small of the back—the sacro spinalis—is permanently tensed in order to keep the spinal column straight and absorb the torque upon the backbone. This leads to an increasing fatigue of the musculature, resulting in painful muscular strains (for example lumbago). Furthermore, declining muscle strength of the sacro spinalis can no longer hold the spinal column upright, with the result that this deviates rearward and passes into the so-called lordosis posture. This produces a permanent overstraining of the lower vertebrae and causes the chronic lower back pains which are widespread in our civilization.
In a chair disclosed in EP-B-0 672 370, the lumbar rest is connected to the seat surface by a mechanism on the base of a parallelogram. A forward or rearward body movement performed by the sitting person leads to an oppositely directed movement of the lumbar rest.
An orthopedic work chair known from DE-A-44 16 964 has a rest disposed on a U-shaped supporting bracket. The seat surface is mounted rotatably by 180° on a ball bearing mounted swivel plate. The rest serves in a work position to support the chest and in a relax position to support the back. The rotatable seat surface allows a change to be made between the work and relax positions without altering the seat position.
JP-A-2004/049816 discloses a work chair having a chest support disposed on a laterally upward-projecting arm. A rotatable seat surface allows dismounting and standing up unimpeded by the chest support arrangement.
From EP-B-1 275 349, an arrangement with arm supports, which can be detachably fastened to a dentist's chair, is known.
REPRESENTATION OF THE INVENTIONThe object of the invention is to provide an ergonomic work chair of the type stated in the introduction, which also allows lengthy working in a bent-forward posture without overstraining of the dorsal musculature.
The object is achieved according to the invention, according to
Advantageous refinements of the invention are the subject of dependent claims.
Further advantages, features and details of the invention emerge from the following description of illustrative embodiments and on the basis of the drawing; this shows schematically in
A work chair 10 represented in
A bracket 28 having a lumbar rest 30 fitted thereto is secured to the rear side of the seat 26 pivotably about a horizontal rotation axis 32. The rotation axis 32 divides the bracket 28 into an angled-off long bracket arm 34, having the lumbar rest 30, and into a short bracket arm 36, the free end of which is connected by a compression spring element 38 to a sliding ring 39 that is disposed on the supporting cylinder 18 concentrically to the supporting column 20 and is mounted such that it is freely rotatable about the cylinder axis z.
To the supporting column 20, a base arm 40 is fastened beneath the base plate 24 by a first base arm part 42, which runs horizontally outward, is pivotable about the cylinder axis z and is lockable in any pivot setting. A second base arm part 44 projects vertically upward from that end of the first base arm part 42 which is remote from the supporting column 20. A chest rest 48 and two arm rests 50 are fitted to a swivel arm 46 mounted on the vertically upward projecting second base arm part 44 rotatably about a vertical axis z′ lying parallel to the cylinder axis z.
As can be seen from
Through the combination of these three measures, health-damaging loads which are generated when sitting with slightly bent-forward posture while practicing manual activities are largely eliminated as follows:
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- The weight of the bent-forward upper body is supported on the chair by the chest rest 48, so that the sacro spinalis no longer has to hold the upper body.
- The small of the back is pressed synchronously with said support by means of the chest rest 48 by a lumbar or lumbar rest 30, via an adjustable spring force, forward in the direction of the upper body or chest rest 48, so that the spinal column cannot deflect rearward into the lordosis posture.
- The arms of the sitting person, who is generally also holding tools or work items in their hands, can be supported on the forward-directed arm rests 50.
As a result of said measures, the musculature of the dorsal section is optimally relieved of the forward-acting torque.
In order that it is possible to sit on the seat 26 in the usual manner, the swivel arm 46, to which the chest rest 48 and the arm rests 50 are fastened, is mounted on the vertically upward projecting second base arm part 44 (
The angular setting of the base arm 40 and of the first base arm part 42 relative to the seat direction x lies roughly between 45° and 60°, so that the freedom of movement of the legs of a person sitting on the work chair 10 is not restricted by the base arm 40, while a torsional moment which is as low as possible acts upon the linkage consisting of base arm 40 and swivel arm 46.
The angular setting between the base arm 40 and the swivel arm 46 in the locking position can be adapted to the body size of the person sitting in the work chair 10, as is explained in greater detail below with reference to
Within the tubular second base arm part 44, a tubular hinge 56 for the rotatable mounting of the likewise tubular swivel arm 46 is arranged. The hinge 56 is fixed by a clamping force acting radially against the inner wall of the second base arm part 44. To this end, the lower part of the hinge 56, which is disposed in the second base arm part 44, is provided with a longitudinal slit 58. A first screw nut 60 is fixed to the inner wall of the hinge 56, for example, with a welding spot 61. A threaded rod 64 engaging in the thread of the first screw nut 60 is led in the axial direction z′ out of the second base arm part 44 and is provided outside the base arm 40 with a handwheel 62. To the threaded rod 64, a second screw nut 66 is fixed beneath the first screw nut 60 such that it is non-displaceable on the threaded rod 64. Between the two screw nuts 60, 66 there is arranged an expanding ring 68. Through rotation of the handwheel 62 and thus of the threaded rod 64, the expanding ring 68 is applied to the first screw nut 60 and, upon continued rotation of the handwheel 62, is compressed by the second screw nut 66 such that it expands toward the inner wall of the tubular hinge 56 provided with a longitudinal slit 58. The hinge 56 is hereupon radially expanded owing to the longitudinal slit 58 and is braced against the inner wall of the second base arm part 44. In this way, the angular setting of the locked swivel arm 46 relative to the base arm 40 is altered by releasing the clamping joint between the hinge 56 and the second base arm part 44, and the base arm 40 can be fixed in the new angular setting of the locked swivel arm 46 by renewed clamping of the hinge 56 in the second base arm part 44.
With the hability of the swivel arm 46 with chest rest 48 and arm rests 50 to swing away to the side, the work chair 10 can also be used conventionally when no activity is performed with bent-forward posture, the sitting person requires space which is unoccupied to the front, or simply wishes to stand up.
The arm rests 50 are secured by means of a fixable ball joint 82 on a radial arm 80, which latter is adjustably fitted to a clamping sleeve 84 on the swivel arm 46 (
The chest rest 48 is fitted in a height-adjustable manner by means of a clamping bracket 90 and a clamping screw 92 to a bar 88 (
The chest rest 48 is configured in a heart shape or is equipped with a rest part 49 supporting the sternum, so that female users of the work chair 10 can lean comfortably against it.
In order to make it easier to sit down and get up, the lumbar rest 30 is designed such that it opens rearward by an angle of about 10° to 20° when the seat 26 is empty (
In the arrangement shown in
In the arrangement shown in
The configuration of lumbar rest 30, chest rest 46 and arm rests 50 also allows an additional use of standard arm rests on the sides of the seat.
For comfortable leaning back, the lumbar rest 30 can be bridged with a second lumbar rest 31 which partially encloses it (
There are manual activities in which the sitting person must lean further forward. This is the case, for example, in dental treatments in which the treating dentist must get very close to the mouth of the patient.
An adjusting lever 126 is hinge-connected, by two arms 128, 130 forming a bell crank mechanism, to respectively one of the two parts 42a, b of the first base arm part 42. A first arm 128 is articulately attached directly to the rotatable part 42b, the second arm 130 to a sliding ring 132 rotatably mounted on the fixed part 42a. The two points of attachment of the arms 128, 130 to the two parts 42a, b are mutually connected by a spring element 134 under tensile stress.
By pressing down the adjusting lever 126, the two parts 42a, b of the first base arm part 42 are drawn apart at the step-shaped dividing point 124 such that the two parts 42a, b detach from their toothing. By leaning forward and applying force to the chest rest, the sitting person can turn the part 42b sliding on the hinge 43 and angle the second base arm part 44 forward counter to the force of a restoring spring—in
The second base arm part 44 supporting the swivel arm 46 is detachably fastened in a clamp 138 disposed on the free end of the part 42b, which clamp can be tightened with a clamping screw 140. This arrangement allows a height adjustment of the entire chest link mechanism, whereby the geometry can be adapted to different body sizes. In addition, the angular setting of the second base arm part 44 can be adapted.
REFERENCE SYMBOL LIST p0 10 work chair
- 12 star base
- 14 radial arm
- 16 casters
- 18 supporting cylinder
- 20 supporting column
- 22 spring element
- 24 base plate
- 26 seat
- 28 bracket
- 29 second bracket
- 30 lumbar rest
- 31 second lumbar rest
- 32 rotation axis
- 34 long bracket arm
- 36 short bracket arm
- 38 compression spring element
- 39 sliding ring
- 40 base arm
- 42 first base arm part
- 42a fixed part of 42
- 42b rotatable part of 42
- 43 hinge
- 44 second base arm part
- 46 swivel arm
- 48 chest rest
- 49 narrow chest rest part
- 50 arm rests
- 52 clamp-type mounting
- 54 clamping screw
- 56 hinge
- 58 longitudinal slit
- 60 first screw nut
- 61 welding spot
- 62 handwheel
- 64 threaded rod
- 66 second screw nut
- 68 expanding ring
- 70 bolt
- 72 first bore
- 74 locking bore
- 76 leaf spring
- 80 radial arm
- 82 ball joint
- 83 swivel joint
- 84 clamping sleeve
- 86 clamping screw
- 88 bar
- 90 clamping bracket
- 92 clamping screw
- 94 clamping sleeve
- 96 first pivot point
- 98 second pivot point
- 100 third pivot point
- 102 sliding rail
- 104 slide
- 106 adjusting screw
- 108 spring element
- 110 intermediate cylinder
- 112 column
- 114 auxiliary bracket
- 116 compression spring element
- 118 swivel joint
- 120 intermediate bracket
- 122 spring element
- 124 step-shaped interface
- 126 adjusting lever
- 128 first arm of a bell crank
- 130 second arm of a bell crank
- 132 sliding ring
- 134 spring element
- 136 torsion spring
- 138 clamp
- 140 clamping screw
- x seat direction
- z supporting cylinder axis
- z′ vertical axis
Claims
1-12. (canceled)
13. A work chair, comprising a supporting cylinder projecting upward from a star base, a supporting column for a base plate with a seat secured on the base plate, which supporting column is mounted in the supporting cylinder displaceably in a vertical cylinder axis, a base arm, which is fitted to the supporting column or to the base plate, and a swivel arm, which has a chest rest and lateral arm rests and is mounted on the base arm such that it is rotatable out of a region of the seat about a vertical axis, and a bracket, which has a lumbar rest and is articulately attached to the base plate, via a lever mechanism having pivot points, such that pressing down the seat causes the lumbar rest to move in the direction of the chest rest.
14. The work chair as claimed in claim 13, wherein the base arm is detachably fitted to the supporting column or to the base plate.
15. The work chair as claimed in claim 13, wherein the swivel arm is mounted on a tubular hinge secured in the base arm, and a resiliently mounted bolt, in a locked usage setting of the swivel arm, passes through a first bore in the hinge and a locking bore in the swivel arm and can be pressed in counter to a spring force to release the locking.
16. The work chair as claimed in 15, wherein the tubular hinge can be radially expanded toward an inner wall of the base arm by means of an expansion device and forms with the base arm a detachable clamping joint.
17. The work chair as claimed in claim 13, wherein the chest rest having a narrow rest part is fitted to the swivel arm such that it can be adjusted in height and pivoted in a seat direction.
18. The work chair as claimed in claim 13, wherein the arm rests are fastened to a radial arm by means of a fixable ball joint, and the radial arm is secured via a swivel joint to a clamping sleeve arranged adjustably on the swivel arm.
19. The work chair as claimed in claim 13, wherein the bracket is fastened to the base plate at a first pivot point rotatably about a horizontal rotation axis, and a second pivot point on the bracket is connected by a spring element to a third pivot point on a sliding ring, which is disposed on the supporting cylinder concentrically to the supporting column and such that it is freely rotatable about the cylinder axis.
20. The work chair as claimed in claim 19, wherein the second pivot point on the bracket is disposed, such that it is adjustable in its position, on a slide guided in a slide rail.
21. The work chair as claimed in claim 13, wherein the seat is mounted via a column in an intermediate cylinder such that it is displaceable in the cylinder axis, the bracket is articulately attached via a second pivot point to an auxiliary bracket fastened to the intermediate cylinder, and a third pivot point on a free end of the bracket is connected by a compression spring element to a first pivot point on the base plate.
22. The work chair as claimed in claim 13, wherein the base plate is fitted to a front side of the seat via a swivel joint on an intermediate bracket and is supported by a spring element, the bracket is articulately attached via a second pivot point on the rear side of the seat to the intermediate bracket, and a third pivot point on the free end of the bracket is connected by a compression spring element to a first pivot point on the base plate.
23. The work chair as claimed in claim 13, wherein the lumbar rest is bridged by a second lumbar rest particularly enclosing it and can be moved through this.
24. The work chair as claimed in claim 13, wherein the base arm has a first base arm part and a second base arm part projecting vertically upward from this and supporting the swivel arm, and the first base arm part is divided into a fixed first part and a rotatable second part, wherein the two parts can be drawn apart at a step-shaped dividing point by means of an adjusting lever and, following rotation of the second part, can be fixed at a preselected tilt setting of the second base arm part.
Type: Application
Filed: Mar 30, 2007
Publication Date: Nov 12, 2009
Inventor: Hans Jurgen Ulrich (Schaffhausen)
Application Number: 12/295,147
International Classification: A47C 7/00 (20060101);