ARM-REST DEVICE

Abstract: A device for supporting a forearm of a person comprises a support arrangement (7) with at least one support surface portion (25) which is movable in an endless path and designed to receive a part of the forearm resting thereon and arranged to move along the path, during motion of the forearm resting thereon in the direction of the extension of said forearm through the friction between the forearm and said portion, while moving its contact point with the forearm in opposite direction in relation to the forearm.

Description: ARM-REST DEVICE FIELD OF THE INVENTION AND PRIOR ART The present invention relates to a device for supporting a person's forearm. Such devices can be employed within different areas, but hereinafter such devices arranged on chairs and the problems connected therewith will be described with the object of elimi¬ nating but not delimiting the invention. As to chairs employed for the execution of different sorts of work, such at office duties, driving a truck, a crane or the like, it is highly important that the person sitting in the chair obtains a good support for his forearms, or at least the right hand fore¬ arm, if he right handed (otherwise the left hand forearm), as the person sits in the same chair and executes a relatively monotonous work during long periods day after day. Though a forearm may seem light and it therefor would not be too tragical if forearm supports are lacking during brief moments of such work, it has been shown that this suggestion not at all proper, but that after a certain number of years an important number of the persons executing a work which is seemingly easy for the body get serious problems with chronicle ache in the back, the shoulders, the forearms or the wrists, and sometimes swelling, particularly in the forearm. At first, such pains leεd to an increase of the number of sickness days for the person in question, whereby also increased costs arise for the employer as a substitute must be found or machines or the like will be standing unused. Later, the problems may lead to that not even rehabilitation measures will be enough to give back the per¬ son's health, the result being early retirement pension or, at best, re-education for another work. For a certain period of time, this problem has begun to become more and more noticed, and to solve it different sorts of arm supports that follow the person during his movements, to constantly give his forearm a support during the execution of different kinds of work, such as, by way of example, the handling of controls in a truck or timber machine, have been suggested. These arm supports then have, besides being pivotable around a generally vertical axle, presented a dis- placeability in relation to a frame of the chair, to be able to fol¬ low the forearm resting thereon in motions directed forwards, as the person in question wishes to stretch himself forward to execute for example a certain lever movement. However, these prior devices present a number of drawbacks. A major drawback consists in that, due to the displaceability often concerning a front part of the arm support, they sometimes will project considerably and be in the way and hit for example table edges. Another drawback is that they, when they have been projected and the person later leaves the contact with the arm support, imperatively have to remain in this projective position, thereby not just being in the way but also presenting a position which probably not at all is the position in which the person wishes to put his forearm next time he will sit down in the chair. These inconveniences of the prior devices easily lead the person who has not yet the abovementioned injury problems into temptation to "cheat" and at least now and then dispense from using the arm support, with the devastating consequences this might lead to. A healthy person may, namely, find these arm supports irritating and just being in the way. BRIEF DESCRIPTION OF THE INVENTION The object of the present invention is to considerably reduce the abovementioned drawbacks of a device for supporting a person's forearm, particularly at arm supports of chairs, but also in other applications. According to the invention, this object is obtained by providing such a device with a support arrangement with at least one support surface portion which is movable in an endless path and designed to receive a part of the forearm resting thereon and arranged to move in said path during motion of the forearm resting thereon in the direction of the extension of the latter through the friction between forearm and said support surface portion, while moving its point of contact with the forearm in op¬ posite direction in relation to the forearm. Thanks to this totally new approach within this field, i.e. to use a support arrangement with a support surface portion which is movable in an endless path for supporting at least a part of the forearm, it thus becomes possible to move the forearm in its lengthwise direction in a safe way while at the same time obtaining a constant support from the device, without the latter therefore being displaced itself, so that it will not project and be in the way and likewise will always have the same position, to make the person using the forearm support device always aware of the position th - of. This obvious improvement in relation to the prior devices of this type will lead to that not even fully health persons will find it as any burden to make use of the device, which will make them happily do this, whereby tensions in the back, the shoulders and arms can be brought down to a minimum level, thereby making them able to stay healthy. According to a preferred embodiment of the invention, the support arrangement comprises a carrier on which a support member presenting said support surface portion is arranged, and the carrier is pivotably arranged in relation to a frame of the device around a generally horizontal axle which is generally perpendicular to the direction that the extension of a forearm is supposed to have as the latter rests on the support arrange¬ ment. Thanks to the arrangement of the support portion on the carrier and the pivotable arrangement of the latter, it is possible for the forearm to always get support from said support surface portion, even if its inclination in relation to the upper arm is to be changed, for example during handling of large control levers. According to another preferred embodiment of the invention the device comprises a band, in its lengthwise direction movably arranged around diverting members and arranged to provide said support surface portion. Hereby the weight of the forearm is very uniformly distributed on larger areas without any un¬ pleasant, concentrated point loads on the forearm while at the same time the latter can be brought back and forth along the support arrangement in a very convenient way. According to yet another preferred embodiment of the invention, which is applied to the use of the device as an arm support of a chair, the support arrangement is arranged with said movable support surface portion in the front part, i.e. the remote part as to a back support of the chair, of the arm support, and the device comprises a second support arrangement providing support surfaces for a person's forearm, said surfaces being translationally immovably arranged in the lengthwise direction of the arm support, said second arrangement being arranged in the rear part of the arm support located adjacent to a back support of the chair. Thanks to this design of the arm support with a translationally immovable rear part and a front part presenting the support surface portion which is movably ar¬ ranged in an endless path, a very advantageous device is obtained. Thanks to the translationally immovably arranged parts, the person using the chair, as he is sitting in a normal position, will always get a very stable support for his forearm as this fixed part gives the arm support device a firmness and in this position the impression of being completely immovable. When on the other hand the person wishes to move his forearm forwards, this can still be accomplished as if the arm support would be displaceable forwards thanks to the motion of the forearm over said support surface portion of the front part of the arm support, so that a continuously good support of the forearm is obtained without the arm support being projected for that reason. The combination of the two support arrangements according to the invention is thus very advantageous and implies a considerable portion of new thinking in relation to prior forearm supporting devices arranged on chairs. Further advantages and preferable characteristics of the invention will be seen in the following description and the remaining dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Below devices are described according to preferred embodi¬ ments of the invention, cited by way of example, with reference to the enclosed drawings, in which: Fig s a perspective view which schematically illustrates a device according to a first preferred embodiment of the inven¬ tion, applied to an arm support of a chair, Fig 2 is an enlarged, partly cut side view of the device of Fig 1 in a certain operational position, Fig 3 is a somewhat smaller view of the device of Fig 2, from above, in a second operational position, Fig 4 is a side view which schematically illustrates the use of the device of Fig 1 , Fig 5 is a simplified perspective view of the device according to a second preferred embodiment of the invention, Fig 6 is a partly cut side view of a device according to a third preferred embodiment of the invention, and Fig 7 is a perspective view of the device of Fig 6, which illus¬ trates how a support arrangement which forms a part thereof can be turned away to an inactive position. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In Fig 1 it is schematically shown how a device according to a preferred embodiment of the invention is arranged on a chair 1 in the shape of an arm support 2. Though only one arm support is illustrated in the Figure, the chair might of course present a second arm support, which can be similar to the one shown or a completely common arm support. The arm support 2 is prefer¬ ably adjustable as to height, which is here illustrated by means of displaceability of a bar 3, which carries the arm support, in a sleeve 4 which is fixed in relation to the chair. At the front part 6 of the arm support, which is the part most remote from the back support 5 of the chair, the latter is provided with a first support arrangement 7 presenting two rolls 9, 10 rotatably arranged around generally horizontal axles on a bogie-like carrier 8, said axles being generally perpendicular to the lengthwise direction of the arm support. The carrier 8 is in its turn pivotably arranged in relation to a frame 12 of the arm support around an axle 1 1 which is generally parallel to the rotational axles of the rolls, and it is, via a spring member which here is a torsion spring 29, spring loadedly arranged in relation to said frame 12, to be able to pivot towards a resting position which corresponds to an orientation of a line connecting the rotational axis of the rolls to be parallel with the lengthwise ex t ension of the arm support and is, as this spring force is defeated, activatable from this resting position by means of the application of lever forces thereon through the weight of a forearm resting or the mantle surfaces of the rolls 9, 10, which is supposed to have happened at the obtaining of the position of Fig 2. Furthermore, the carrier 8 is provided with a projection 13 which, during the pivoting of the carrier 8 in an anticlockwise direction as seen in Fig 2, is arranged to turn against a stop member 14, which is arranged on the frame, for defining said resting position, which position will be taken with a certain pretension of the plate spring 29. Furthermore, the rotational axles 15 of the rolls are spring suspensϊoned in the carrier 8, to allow them to be pressed down from an unloaded resting position (Fig 1 ) as a spring force is overcome during the application of some of the weight of the forearm on the mantle surfaces thereof. Therefore springs 16 are suggested in Fig 2. At its rear part 17, which is located adjacent to the back support 5, the arm support comprises a second support arrangement 20 which provides support surfaces 18, 19 which are trans' ^tionally immovably arranged. This second support arrangement is arranged to receive the elbow and the portions adjacent to the elbow of a person's forearm resting on the support surfaces 18, 19 thereof as the person is sitting in the chair with his back resting against the back support and with his upper arm hanging generally straight downwards. Thereby a part of said support surfaces is formed by a turning disk 21 , which is rotatable around an axle which is generally perpendicular thereto, while the surrounding support surfaces 19 are completely fixed in re¬ lation to the frame of the arm support, the object of said disk being explained later. Furthermore, the arm support 2 is adjustable to different fixed inclination positions around a generally horizontal axle which is generally perpendicular to the lengthwise direction of the arm support and is located in the region of the part of the arm support adjacent to the back, which in Fig 2 is illustrated by means of a tap 22, which is spring-loadedly arranged on the arm support and supposed to snap into different recesses 23 of a circular arch portion of the bar 3 carrying the arm support. In this way it becomes possible to adjust the inclination of the arm support to the very position which is requested in a certain situation. In the front the arm support is provided with a nose 28 to be able to "climb" over an edge of a desk for example when confronting such a one. Furthermore, the arm support 2 is pivotably arranged in relation to the rest of the chair around an axle at its rear part adjacent to the back support, such as illustrated in Fig 3, said axle being generally perpendicular to the support plane of the arm support. This pivot axle conforms with the central axis of the bar 3 and preferably with the rotational axis of the turning disk 21 and the point where the forearm hinge of a person sitting in the above¬ mentioned normal position in the chair is supposed to be. The arm support is activated by way of a spring suspension to pivot around the axle 24 towards a resting position in which it points generally straight forward from the back support of chair. The mantle surface 25 of the rolls 10 are designed in a slightly concave way to make a swinging of a forearm resting on the arm support easier result in the arm support being entrained in a pivoting motion, illustrated in Fig 3, and a better retaining of the forearm against the arm support. The support surfaces 18 of the turning disk and the surrounding support surfaces 19 of the second support arrangement are preferably made of a some¬ what rough material, while the mantle surfaces 25 of the rolls can be made of a somewhat smooth*^ - material, such as leather or plastic. Prefer a bly the rolls are a, ranged in such a way that they can easily . lifted away from the carrier for exchange, maintenance or removal if the arm support is to be converted into a conventional arm support. The operation of the device described above is as follows: a person sitting in the chair 1 is in his normal position supposed to have the portions of his forearm adjacent to the elbow resting on the support surfaces 18, 19, which are translationally immovably arranged, and the portions of his forearm adjacent to the wrist resting on the mantle surfaces 25 of the rotatable rolls 9, 10. When this person wishes to execute some work with his hand, e.g. manoeuvre a control lever 30, such as illustrated in Fig 4, he can execute the following motions: the forearm can be moved in its lengthwise direction during rotation of the rolls 9 and 10 through the friction caused by the weight of the forearm to make the support surface portions provided by the mantle surfaces of the rolls move upwards along the arm, the forearm being provided with a good support from the rolls all the time. During such motion the weight of the forearm will successively be transferred from the support surfaces 18, 19, which are translationally immovably arranged, to the mantle surfaces of the rolls. Thereby the rolls 9, 10, through the springs 16, can be adjusted in height according to the force of the weight applied thereto. If by way of example the person in the position shown in Fig 4 wishes to press down said lever, the carrier 8 will be activated to pivot as illustrated in ™ ig 2 and thereby the forearm will continuously obtain a require, _ support from the mantle surfaces of the rolls. If a sideward motion of the lever is to be carried out, the person executes this lever motion and the arm support thereby follows the forearm in its motion by pivoting around the axle 24, as shown in Fig 3. Thereby, the turning disk 21 can facilitate such pivoting but it is also possible to omit it completely while the second support arrangement presents one single, continuous, fixed support surface. In addition thereto the base setting of the inclination of the arm support can be adjusted when so is needed by pulling the arm support 2 upwards or downwards and thereby snapping the tap 22 into any of the recesses 23. The person using the arm support can thus obtain a perma¬ nently good support for his forearm and thereby relieve muscles therein and in the upper arm, the back, and in the back of the head and shoulder portions during the use of the device accord¬ ing to the invention. This is obtained without any part of the arm support being projected and risking to be in the way and hitting different objects, such as, by way of example, an edge of a desk. There is also provided a possibility to easily move the forearm in its lengthwise direction as it rests upon the arm support, without the arm support tending to slip away and make a holding of the forearm in normal position more difficult, as the arm support presents the translationally immovable second support arrangement. Another important quality of this device is the fact that the arm support, during the lack of a forearm resting thereon, will always take the basic position shown in Fig 1 with the arm support pointing straight ahead, thanks to the spring suspension around the axle 24, the support portion, provided by the mantle surfaces 25, pointing generally parallel to the support surfaces 18, 19 thanks to the spring loading of the carrier 8 towards its resting position, and the mobility of the first support arrangement in relation to the forearm without any displacement in relation to the rest of the chair, thanks to the arrangement of the rolls 9, 10 in accordance with the invention. Normally, the total weight of the forearm does nc, rest on an arm support of this kind, but maybe 30-80 % of it, which is just what is needed to enable the person in question to sit and be relaxed in the groups of muscles concerned. In Fig 5 a forearm supporting device according to a second preferred embodiment of the invention is illustrated, which device is supposed to be applied to a table 26 in the region of an edge 27 of the table top. Also this device presents a carrier 8' with rolls 9', 10' rotatably arranged therein in a way similar to the one shown in Fig 2. The carrier 8' is thus pivotably arranged around an axle generally parallel to the rotational axle of the rolls from the resting position shown in Fig 5 to different positions in relation to the table edge 27, with its end adjacent to the table edge pointing downwards. In addition thereto, the carrier 8' is turnably arranged in relation to the table, around its generally horizontal centre axis. This device can be used by persons sitting by a desk and needing to be able to incline their forearm towards the table during execution of some sort of work, e.g. on a keyboard. Thereby, the forearm may rest upon the mantle surfaces of the rolls, making the forearm mobile in its lengthwise direction under constant support from the rolls. The inclination of the arm in relation to the horizontal plane as well as its direction can also be varied, thanks to the pivotable arrangement of the carrier 8' and its turnability around its centre axis. The device according " ■ the embodiment shown in Figs 6 and 7 presents a plurality of . . .Is 31 which are rotatably arranged be¬ side each other around axles that are parallel to each other, and arranged to form a support for a band 32, which is placed around these and diverted by means of the two outer rolls, said band being arranged to provide with support surface portions for the forearm of a person using the chair. The rolls 31 are ar¬ ranged on a carrier not shown which in its turn is pivotably arranged around a horizontal axle 33 which is generally parallel to the axles of the rolls. Around the axle 33 the carrier is activated by means of spring loading towards a resting position which generally corresponds to the normal extension of a forearm resting on the band. The first support arrangement, formed by the rolls 31 and the band 32, is pivotably arranged around an axle 35 in relation to a second support arrangement 34 which is adjacent to the back support and fixedly arranged in relation to the rest of the chair, said axle being generally perpendicular to the support plane of the second support arrangement and located at the rear part of the arm support adjacent to the back support. Said first support arrangement is also pivotably arranged in relation to the second support arrangement downwards from an active support position around a generally horizontal axle to a retracted position, as illustrated in Fig 7. Thanks to the arrangement of an endless band 32, which is placed around rotatably arranged rolls, as a member for providing a support surface portion for the forearm, the forearm can rest very conveniently on this support surface portion and be moved along the latter as the weight of the part of the forearm in question is evenly distributed on the band. The invention is of course not in any way delimited to the preferred embodiments described above, but a plurality of possibilities of modifications thereof should be obvious for a man skilled in the art without diverging from the scope of the in¬ vention. By way of example a single or more than two rolls could be used in the first support arrangement. Instead of one roll it would also be possible to arrange an endless band, which provides a support surface portion which is movable in an endless path, and on which band the forearm would then rest and which would be movable in its path like a conveyor band through affection from a friction force from the forearm. The patent claim definition "support plane" of the arm support is here referred to as the plane in which a forearm is supposed to get support while it is resting on the arm support.

Claims: Claims 1. A device for supporting a person's forearm, characterized in that it comprises a support arrangement (7) with at least one support surface portion (25, 25', 32) which is movable in an endless path and designed to receive a part of the forearm resting thereon, and arranged to move along the path during motion of the forearm resting thereon in the direction of the ex¬ tension of the latter through the friction between forearm and said support surface portion, while moving its contact point with the forearm in opposite direction in relation to the forearm. 2. A device according to claim 1 , characterized in that the support arrangement comprises a carrier (8, 8') on which a support member (9, 10, 9', 10', 32) presenting said support surface portion is arranged, and in that the carrier, in relation to a frame (12, 26) of the device, is pivotedly arranged around a generally horizontal axle (33) which is generally perpendicular to the direction that an extension of a forearm is supposed to have while resting upon the support arrangement. 3. A device according to claim 1 or 2, characterized in that it comprises a band (32), which in its lengthwise direction is arranged around diverting members (31 ) and arranged to provide said support surface portion. 4. A device according to claim 3, characterized in that it comprises a plurality of rolls (31) which are rotatably arranged beside each other around axles that are parallel to each other and arranged to form supports for said band (32), which is arranged around the latters in a generally tense way. 5. A device according to claim 1 or 2, characterized in that it comprises a rotatable roll (9, 10, 9', 10') which is arranged to provide said support surface portion by means of its mantle surface (25, 25'). 6. A device according to claim 5, characterized in that the roll presents a concave mantle surface. 7. A device according to claim 5 or 6, characterized in that the rotating axle (15) of the roll is spring suspensioned for allowing the roll to get pressed down from an unloaded resting position, as a spring force is overcome during application of some of the weight of a forearm on the mantle surface (25, 25') thereof. 8. A device according to claim 5, characterized in that the sup¬ port arrangement comprises a plurality of rolls (9, 10, 9', 10'), arranged one after another and also arranged to receive por¬ tions of a forearm resting thereon, said portions following each other in said direction. 9. A device according to claim 2 and 8, characterized in that the support arrangement comprises two rolls arranged on the carrier (8, 8') in a bogie-like way. 10. A device according to claim 2, characterized in that the carrier (8, 8') is springloadedly arranged in a pivotable way towards a resting position in relation to said frame (12, 26) and is activatable from this resting position by overcoming a spring force through application of lever forces thereon by means of the /eight of the forearm resting on said support surface portion. 11. A device according to any of claims 1-10, characterized in that it is arranged as an arm support (2) of a chair. 12. A device according to claim 11 , characterized in that the support arrangement (7) is arranged with said movable support surface portion in the front part (6) of the arm support remote from a back support of the chair and in that the device comprises a second support arrangement (20, 34) which provides support surfaces (18, 19) for a person's forearm, which surfaces are translationally immovably arranged in the length¬ wise direction of the arm support, and which is arranged in the rear part (17) of the arm support adjacent to a back support (5) of the chair. 13. A device according to claim 12, characterized in that the first support arrangement is pivotably arranged in relation to the second support arrangement (34) around an axle (35) localized at the rear part of the arm support adjacent to the back support, said axle (35) being generally perpendicular to the support plane of said second support arrangement. 14. A device according to claim 12 or 13, characterized in that the first support arrangement is pivotably arranged in relation to the second support arrangement (34) from an active support position and downwards, around a generally horizontal axle, to a retracted position. 15. A device according to any of claims 12-14, characterized in that the rear, second support arrangement (20, 34) is arranged to receive the elbow and the portions adjacent to the elbow of a person's forearm resting upon its support surfaces (18, 19), as the person is sitting in the chair with his back resting against the back support and as his upper arm hanging virtually straight down, and the front, first support arrangement (7) is arranged to receive the portions of the person's forearm adjacent to the wrist to rest upon said support surface portion (25, 32), with the person in said position. 16. A device according to claim 12, characterized in that at least a part of said support surfaces (18, 19) of the second support arrangement (20) are provided by a disk (21), which is turnably arranged around an axle which is generally perpen¬ dicular to the support plane of the arm support, the turning point of the disk being arranged generally at the location intended to receive the elbow of a person sitting in the chair with his back resting against the back support and his upper arm hanging generally straight down. 17. A device according to claim 1 1 , characterized in that the arm support (2) is pivotably arranged in relation to the rest of the chair around an axle located at its rear part (17) adjacent to the back support, the axle being generally perpendicular to the support plane of said support, and that the arm support is activated through spring loading to pivot around said axle (24) toward a resting position, in which it points generally straight forward from the back support of the chair. 18. A device according to claim 11 , characterized in that the arm support (2) is adjustable into different, fixed inclination po¬ sitions around a generally horizontal axle which is generally perpendicular to the lengthwise direction of the arm support and is located in the region of the part of the arm support adjacent to the back. 19. A device according to claim 10 and 11 , characterized in that said resting position of the carrier (8) corresponds to an orientation of said support surface portion (25) generally parallel with the lengthwise direction of the arm support, and in that it comprises stop members (13, 14) arranged to inhibit the carrier from pivoting in relation to the frame (12) from this resting position with its portions most adjacent to the back sup¬ port of the chair downwards.

Inventors: PETTERSSON BOERJE AHSTON, PETTERSSON, BOERJE, AHSTON
Applicants: PETTERSSON BOERJE AHSTON, SITTAB STOL AB, PETTERSSON, BOERJE, AHSTON
Application year: 1995
Main classification: A47C7
IPC codes: A47C1, A47C7