Armrest apparatus installed in chair for computer work

The present invention relates to an armrest apparatus installed in a chair for a computer work. An armrest member which is freely movable on a horizontal surface by a link apparatus is provided in an upper portion of an armrest body vertically installed at both sides of a seat of a chair. The armrest apparatus is used as a common armrest for a chair at a usual time on which a user's arms are placed in such a manner that an armrest member is closely contacted with an upper surface of an armrest body or is lifted upwardly. The armrest member is upwardly lifted at the height at which a keyboard work is conveniently performed during a computer work, so that a user's arms are freely movable on the armrest on a horizontal surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an armrest apparatus installed in a chair for a computer work, and in particular to an armrest apparatus installed in a chair for a computer work which may be used as an armrest in a chair and may be used as an armrest for a computer work when a user sits on a chair and performs a computer work.

2. Description of Related Art

When a user performs a computer work in a state that a user sits on a chair, the user's arms must be upwardly lifted above an upper surface of a table for operating a keyboard or mouse disposed on an upper surface of a table. When a keyboard and mouse are disposed in a keyboard drawer installed below an upper plate of a table, the user must operate a keyboard and mouse in a state that the user's arms are upwardly lifted, so that the user easily feels a fatigue.

Various armrests are developed for conveniently supporting the user's arms during a computer work in the conventional art. However, almost conventional armrests for a computer are fixedly installed in the table.

However, in the conventional armrest for a computer in which the armrest is fixedly installed in the table, left and right sides are separately fabricated, and a bracket, which supports and surrounds the front surface of the upper plate of the table in the upper and lower portions, is fixed by screws. In this case, the bracket may damage the upper plate of the table. In addition, in the case that a glass plate is provided on the upper surface of the table, when the bracket is fixed using the screws, the bracket may over-pressurize the glass plate, so that the glass plate may be broken.

In addition, when the installed computer is moved to another table, the armrest for a computer installed in the table must be disassembled and then is installed in another table again to which the computer is moved for thereby causing much inconvenience. When the armrest is installed again in the above manner, the table may be damaged or the glass plate provided on the upper surface of the table may be easily broken.

Almost chairs include an armrest for supporting the user's arms, and all armrests installed in the chair have a height lower than the upper plate of the chair which is generally used in office.

Therefore, when the user performs a computer work in a state that the user sits on the chair, since the user must upwardly lift his arms above the upper plate of the table, the armrests of the chair are not capable of efficiently supporting the user's arms. In addition, since the armrests of the chair are fixed to the chair, it is impossible to effectively support the user's arms.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide an armrest apparatus installed in a chair for a computer work which overcomes the problems encountered in the conventional art.

It is another object of the present invention to provide an armrest apparatus installed in a chair for a computer work which is capable of more efficiently using an armrest member of a chair.

It is another object of the present invention to provide an armrest apparatus installed in a chair for a computer work in which an armrest apparatus for a computer work is used as a common armrest when a user who sits on a chair does not work a computer work, and an armrest apparatus for a computer work is upwardly ejected, so that a user's arms are stably placed on an armrest member for thereby efficiently performing a computer work by providing an armrest apparatus for a computer work which also has an inherent armrest function at both sides of a seat of a chair.

It is another object of the present invention to provide an armrest apparatus installed in a chair for a computer work in which an armrest apparatus for a computer work installed in a chair is extended in a horizontal direction and is rotatable in all directions, so that the user's arms are freely movable during a computer work.

It is another object of the present invention to provide an armrest apparatus installed in a chair for a computer work in which when a user removes his arms from an armrest member for another work while a computer work is done using an armrest apparatus for a computer work, the armrest apparatus is not moved and maintains a previous current state, and when the user rotates the armrest apparatus in a certain direction, the armrest apparatus maintains a moved state, so that it is possible to prevent any disturbance by the armrest apparatus when changing the current work to another work, and it is possible to quickly restart the current work after the another work is finished.

To achieve the above objects, there is provided an armrest apparatus installed in a chair for a computer work which includes an armrest body which is vertically fixedly installed at one side of a chair, an upper receiving space which is formed in an inner upper portion of the armrest body and is formed widely in front and rear sides in such a manner that the upper potion of the same is opened, a lifting and lowering guide space which is formed in a lower portion of the upper receiving space of the armrest body and is formed in a vertical direction in such a manner that the lifting and lowering guide space communicates with the upper receiving space, a link body which is received in the upper receiving space of the armrest body or which is ejected therefrom based on a lifting operation, a lifting and lowering guide member in which an inner rod is movable in upward and downward directions in the interior of an outer rod and is installed in a lifting and lowering guide space of the armrest body and is liftable therein, and an upper end of the outer rod is rotatably engaged to the lower link of the link body, and a lower end of the same is elastically supported by a main spring, and an upper end of the inner rod passes through an operation groove formed in the lower link of the link body in such a manner that the upper end of the same is movable in upward and downward directions, and a circular ring is elastically supported by a subsidiary spring installed in the operation groove, for thereby guiding a receiving operation and ejection operation of the link body, a first link member which is installed in such a manner that the first link member is horizontally movable in a slide moving space formed between the upper and lower links of the link body, a first pin member which includes upper and lower ends which pass through a rear end portion of the first link member and are horizontally movably and rotatably installed in upper and lower guide grooves which are opposite to each other in the lower and upper surfaces of the upper and lower links of the link body based on a horizontal movement and rotation, a second link member which is installed in a front end portion of the first link member and in an upper portion of the upper link of the link body, a second pin member which rotatably connects each rotation end of the second link member, and an armrest member which is rotatably connected with respect to a free end of the second pin member and is placed on an upper surface of the armrest body and is lifted for thereby opening and closing the upper receiving space and is used as an armrest on which a user's arms are placed at a usual time and is upwardly lifted during a computer work and is freely movable on a horizontal surface.

DETAILED DESCRIPTION OF PREFFERED EMBODIMENTS

FIG. 1is a side view illustrating a chair for describing an installation state of an armrest apparatus according to the present invention,FIG. 2is a side view illustrating a state of use of an armrest apparatus according to the present invention,FIGS. 3 and 4are views illustrating a state that an armrest apparatus is received in a body and a state that an armrest apparatus is extracted from a body according to the present invention,FIG. 5is a cross-sectional view taken along line A—A ofFIG. 3,FIG. 6is a cross-sectional view taken along line B—B ofFIG. 4,FIGS. 7 and 8are cross-sectional views for describing an operation state of a link body and a lifting and lowering guide member of an armrest apparatus according to the present invention,FIGS. 9 and 10are cross-sectional views illustrating an operation state of a first pin member which connects a link body and a second link member of an armrest apparatus according to the present invention,FIG. 11is a cross-sectional view taken along line C—C ofFIG. 9,FIGS. 12 and 13are cross-sectional views illustrating an operation state of a second pin member which connects a first link member and a second link member of an armrest apparatus according to the present invention, andFIG. 14is a cross-sectional view illustrating an assembled state and operation state of a third pin member which connects a first link member and an armrest member of an armrest apparatus according to the present invention.

In the drawings, reference numeral1represents a chair. In the above chair1, a seat12is provided on an upper portion of a leg support unit11which is integrally connected with a support leg (not shown) having wheels, and a backrest13is installed in a back side of the seat12.

In the present invention, an armrest apparatus for a computer work is installed in both sides of the seat12of the chair1. The armrest apparatus for a computer work is constructed in such a manner that the arms of the user who sits on the chair are comfortably supported by the armrest apparatus for a computer work. In addition, the armrest apparatus for a computer work may be installed in the inner sides of the armrests installed at both sides of the seat12of the chair1.

In the armrest apparatus for a computer work according to the present invention, an armrest body2is fixedly vertically installed at at least one side, preferably at both sides of the seat12of the chair1. The left and right wise width of an upper receiving space21of the armrest body2has wider front and rear portions of the same for thereby receiving a link portion therein.

A lifting and lowering guide space22is longitudinally formed in the lower portion of the upper receiving space21of the armrest body2in the upper and lower directions. The upper portion of the lifting and lowering guide space22communicates with the upper receiving space21, and the lower portion of the same is closed.

The lifting and lowering guide member3is inserted into the lifting and lowering guide space22of the armrest body2in such a manner that the lifting and lowering guide member3is slidable therein in the upward and downward directions. The lifting and lowering guide member3is formed of an outer rod31formed in a pipe shape and an inner rod32which is inserted onto the outer rod in a upwardly and downwardly slidable method.

The channel-shaped link body4, in which the upper and lower links41and42are integrally formed, is installed in the upper receiving space21in such a manner that the channel-shaped link body4is received and extracted in the upward and downward directions. The link body4is engaged with the lifting and lowering guide member3.

Namely, in a rear lower portion of the link body4, an upper end of the outer rod31which forms the lifting and lowering guide member3is rotatably installed in a support bearing43installed in a rear lower portion of the link body4. An upper end of the inner rod32of the lifting and lowering guide member3passes through an operation groove44formed in a rear end of a lower link42of the link body4and is exposed through a sliding space45formed between the upper and lower links41and42. A circular ring33outwardly protruded from an upper portion of the inner rod32is received in the inner portion of the operation groove44and is elastically supported by a subsidiary spring34.

A main spring35is elastically installed in a lower portion of the outer rod31of the lifting and lowering guide member3for lifting the link body4in the upward direction of the armrest body2escaping from the upper receiving space21. A lifting control ring36is protruded at an intermediate portion of the outer rod31in a circular shape for preventing the lifting and lowering guide member3from being lifted when the link body4is escaped from the upper surface of the upper support member141.

In addition, when the lifting and lowering guide member3is lifted by an elastic force of the main spring35, it is preferred that the lifting and lowering guide member3is slowly lifted, not fast. In order to implement the above operation, a rack gear23is attached to one side of the lifting and lowering guide space22, and a lifting and lowering guide gear37engaged with the rack gear23is installed in the lifting and lowering guide member3. The lifting and lowering guide gear37is rotatably attached by a pin shaft38which is inserted into a hole which passes through the outer rod31and the inner rod32in a horizontal direction in a lower portion of the lifting control ring36and is installed in the inner rod32.

When the lifting and lowering guide member3finishes the lifting operation and lowering operation, it is needed to control the above operations. A lifting control pin24and lowering control pin25are installed in the portions of the lifting guide space22of the armrest body2in the opposite directions from each other. The lifting control pin24and the lowering control pin25are elastically exposed by the spring241and251.

A lifting control hole311and a lowering control hole312to which the lifting control pin24and lowering control pin25are alternately caught are formed in both sides of the outer rod31of the lifting and lowering guide member3.

In addition, a lifting protrusion321and a lowering protrusion322are formed in both sides of the inner rod32of the lifting and lowering member3for releasing the catching operations of the lifting and lowering control pins24and25which are alternately caught by the lifting and lowering control holes311and312.

The first and second link members5and6are assembled to the link body4in a connected state. The assembling construction of the first link member5will be described.

The first link member5is assembled movably and rotatably in a horizontal direction with respect to the sliding space45of the link body4.

The first pin member7which passes through the rear end portion of the first link member5in the vertical direction is rotatably and horizontally movably inserted into the upper and lower guide grooves411and421formed in the lower and upper surfaces of the upper and lower links41and42of the link body4.

The first pin member7is constructed in such a manner that upper and lower cylinders71and72are engaged. The upper cylinder71is horizontally movably and rotatably inserted into the upper guide groove411formed in the upper link41of the link body4and includes a lower end inserted into a through hole51formed in a rear end of the first link member5and being rotatable by a bearing52. The lower cylinder72of the first pin member7is horizontally movably installed in the lower guide groove421formed in the lower link42of the link body4and is inserted in such a manner that the lower cylinder72is movable in the upper and lower directions in the lower side of the through hole51and is engaged to a lower end of the upper cylinder71. The upper cylinder71engaged to an upper portion of the lower cylinder72is engaged in such a manner that the upper cylinder71is movable in the upward and downward directions and is elastically supported by the support spring73in a stably supported structure.

A plurality of control grooves73are formed in an outer circumferential surface of the upper cylinder71of the first pin member7at a regular interval in a circular shape. The rotation operation of the first link member5is elastically controlled in such a manner that a ball76which is elastically supported by a ball spring75is selectively elastically supported by one of a plurality of control grooves74at both sides of the through hole51of the first link member5. Namely, in the case that no load is applied to the first link member5(in the case that the computer user removes his arm from the armrest member), when the ball75is elastically inserted in the control groove74based on the upward movement of the upper cylinder71by an elastic force of the support spring73, the rotation operation of the first link member5is controlled by the ball75, so that the first link member5is not naturally rotated. On the contrary, in the case that a load is applied to the first link member5(in the case that the computer user rests his arm on the armrest member), the first link member5is slightly downwardly moved in the direction of the lower link42, and the upper cylinder71of the first pin member7is moved together with the first link member5, so that each control groove74is loosened from the ball76and is hidden in the inner side of the upper end of the lower cylinder72, so that the first link member5is freely rotated with respect to the first pin member7. In addition, in a state that the control groove74is hidden in the inner side of the upper end of the lower cylinder74, the ball76is elastically contacted with an outer circumferential surface of the upper cylinder71for thereby smoothly guiding the rotation operation of the first link member5.

The ball76which elastically supports an outer circumferential surface of the first pin member7is provided in more than two balls, so that more than two balls elastically support at the opposite positions.

A slit groove422is formed in a horizontal direction in an inner surface of both sides of the lower guide groove421of the lower link42in order for the first pin member7not to move when the first pin member7, which is horizontally moved in the upper and lower guide grooves411and412formed in the upper and lower links41and42, is horizontally moved, and a guide wing721is protruded from an outer circumferential surface of the lower cylinder72of the first pin member7and is slidably inserted into the slit groove422.

In addition, a slanted surface53and a pressing surface54are formed in a lower surface of a rear end portion5bof the first link member5for pressing the upper end of the inner rod32of the lifting and lowering guide member3. The slanted surface53presses the upper end of the inner rod32when the first link member5slidably moves in the sliding space45of the link body4, and the pressing surface54limits the upper end of the inner rod32pressed by the slanted surface53and prevents the lifting and lowering guide member3from being upwardly lifted.

The second pin member8which connects a front end5aof the first link member5and a rotation end6aof the second link member6will be described.

The upper cylinder81of the second pin member8is tight-inserted into a rotation end6aof the second link member6, and the lower cylinder82is rotatably installed by the bearing83installed in a support hole821formed in the front end portion5aof the first link member5. The lower end of the upper cylinder81is connected in such a manner that the lower end of the same surrounds the upper end of the lower cylinder82and is rotatable and movable. The above upper and lower cylinders are elastically installed by the support spring87.

A plurality of control grooves84are formed in an outer circumferential surface of the lower cylinder82at a regular interval in a circular shape. More than opposite two balls85are elastically supported by the ball spring86in the support hole82and are constructed in order for the control groove84to be elastically supported.

In the above construction, when a certain load is applied to the first link member (in the case that the computer user rests his arm on an armrest member), the first link member6is slightly downwardly moved by the applied load. The upper cylinder81of the first pin member8is downwardly moved together with the first link member6. The lower end of the same outwardly moves the ball85which elastically supports the control groove84and hides the control groove84. When the ball85elastically contacts with an outer circumferential surface of the lower portion of the upper cylinder81, the first link member6is smoothly rotated. On the contrary, when no load is applied to the first link member6(in the case that the computer user removes his arm from the armrest member), the upper cylinder81is upwardly moved by the elastic force of the support spring86for thereby exposing the control groove84, and the ball85elastically supports the control groove84, so that the first link6does not naturally rotate.

The armrest member9assembled to a free end6bof the second link member6will be described.

The armrest member9is formed in a longitudinal shape in such a manner that a user's arm is supported by and properly placed on an upper surface of the armrest body2which is vertically installed at both sides of the chair1. The arm support member9is rotatably engaged to a spherical portion911of an upper end of the third pin member91fixedly attached to an upper surface of the free end6bof the second link member6and is capable of adjusting the position by rotating the armrest member9in a horizontal direction and implements a tilting operation in all directions.

In the above description, the third pin member91is freely tiltable in all directions by the spherical portion911. However, the above construction is not limited thereto. In another preferred embodiment of the present invention, as shown inFIGS. 12 and 13, the ball85, the support spring86and the control groove84may be identically constructed. Therefore, the third pin member91may be rotatably connected to the free end91, and the armrest member9may be fixed to an upper end of the third pin member91. The armrest member9may be rotatable on the horizontal surface by a movement of arm placed on the armrest member9. When an external force is not applied, the armrest member9is not rotated based on the stopper function of the ball85.

In addition, when the computer is not used, the armrest member9is lowered. The opened upper portion of the upper receiving space21of the armrest body2is closed and fixed in a horizontal state, so that the arms of the user who sits on the chair1are stably supported. When the user uses the computer. The armrest member9is upwardly lifted at the same height as the height of the upper plate of the table in which the computer is installed for thereby stably supporting the arms of the user who uses the computer.

An elastic support member27is installed in a front upper end of the upper receiving space21of the armrest body2for elastically supporting a rotation end6a(or an upper link of the link body) of the second link member6which is elastically supported using the spring26. When the first and second link members5and6are received in the upper receiving space21of the armrest body2, it is possible to continuously maintain a state that the pressing surface formed in the rear end5bof the first link member5continuously presses an upper portion of the inner rod32of the lifting and lowering guide member3based on a supporting operation in which the elastic support member27elastically pushes the second link member6. In addition, in the case that the armrest member9is forwardly moved in the direction of the elastic support member27, the second link member6elastically supports the elastic support member27, so that the pressing surface54and the slanted surface53formed in the rear end5bof the first link member5are loosened at the upper end of the inner rod32of the lifting and lowering guide member3, whereby it is possible to eject the armrest apparatus according to the present invention from the armrest body2.

In addition, a permanent magnet61is embedded in a lower surface of the free end6bof the second link member6for easily inputting the armrest apparatus into the upper receiving space21of the armrest body2, and a permanent magnet46may be embedded in a rear side upper surface of the upper link41of the link member4. At this time, the permanent magnets61and64are embedded at the positions in which two permanent magnets embedded in the second link member6and the upper link41pull each other in the upper and lower vertical directions when the second link member6is rotated in parallel with respect to the upper portion of the upper link41. In addition, two opposite permanent magnets47and55are embedded in the inner end portion of the sliding space45of the link body4and the end of the rear end portion5bof the first link member5for thereby pulling each other. Therefore, when inserting the first link member5into the sliding space45of the link body4, it is possible to implement an easier insertion operation of the first link member5based on a magnetic force between the permanent magnets47and55. It is possible to implement an efficient operation that the slanted surface53formed in the lower surface of the rear end portion5bof the first link member presses the upper end of the inner rod32of the lifting and lowering guide member3based on the magnetic forces of the permanent magnets47and55.

The operation of the present invention will be described with reference to the accompanying drawings.

FIG. 1is a view illustrating a state that the chair1is used in usual. As shown therein, the armrest apparatus, namely, the link member4and the first and second link members5and6are received in the upper receiving space21of the armrest body2as shown inFIG. 3, and the armrest member9is placed on the upper surface of the armrest body2in a horizontal direction, so that the arms of the user who sits on the chair1are stably supported by the armrest member9.

FIG. 2is a view illustrating a state that the armrest apparatus is ejected from the armrest body2in order for the user to perform a computer work. When ejecting the armrest apparatus, the armrest member9ofFIG. 3is forwardly moved in the forward direction of the chair1, and the rotation end6aof the second link member6connected to the armrest member9by the third pin member91elastically pushes the elastic support member27. Therefore, the first link member5connected with the rotation end6aof the second link member6is forwardly moved in the direction from the sliding space45of the link body4by the second pin member8, so that the pressing surface54formed in the lower portion of the rear end portion5bof the first link member5is released from the upper portion of the inner rod32of the lifting and lowering guide member3. At this time, since the lifting operation of the outer rod31of the lifting and lowering guide member3is controlled by the lifting control pin24, the link body4and the first and second link members5and6received in the upper receiving space21are not lifted upwardly, and only the inner rod32of the lifting and lowering guide member3is upwardly lifted by an elastic force of the subsidiary spring34as shown in FIG.8. In the inner rod32which is upwardly lifted by the elastic force of the subsidiary spring34, the circular ring33is lifted up to the inner end of the operation groove44, and the lifting protrusion321formed in an outer circumferential surface of the inner rod32is upwardly lifted and pushes the lifting control pin24, so that the lifting control pin24is released from the lifting control hole311.

When the lifting control pin24is released from the lifting control hole311by the lifting operation of the lifting protrusion321, the elastic force of the main spring35is applied to the outer rod31, so that the lifting and lowering guide member3is elastically lifted in the upward direction for thereby upwardly lifting the link member4as shown in FIG.4. At this time, the lifting and lowering guide gear37installed at an intermediate portion of the inner rod32slides in a state that it is engaged with the rack gear23and guides the lifting operation of the lifting and lowering guide member3, so that the lifting and lowering guide member3is slowly lifted. Therefore, the link member4and the armrest member9are slowly lifted, so that it is possible to prevent any accident when the user ejects the armrest apparatus in a state that the user sits on the chair.

The lifting and lowering guide member3which upwardly lifts the link body4is upwardly lifted until the lifting control ring36contacts with the upper end of the lifting and lowering guide space22. When the lifting operation of the lifting and lowering guide member3is completed, the lowering control pin25elastically installed in a portion opposite to the lifting control pin24is elastically inserted into the lowering control hole312formed in the outer rod31of the lifting and lowering guide member3, so that the lowering operation of the lifting and lowering guide member3is controlled by the lowering control pin312as shown in FIG.6.

In a state that the lifting operation of the lifting and lowering guide member3is completed, the lower portion of the lower link42is fully escaped from the upper portion of the armrest body2. The height of the armrest member9, which is fully escaped from the armrest body2, is the same as the height at which the computer user conveniently uses the keyboard and mouse placed on the table.

When the link body4is fully exposed from the upper side of the upper receiving space21of the armrest body2, the user holds the armrest member9and rotates the second link member6in the forward direction and forwardly moves the same, so that the first link member5is escaped from the sliding space45of the link body4. In this state, the computer user is capable of freely moving the armrest member9in all directions by putting his arms on the armrest member9.

In addition, when the user performs a computer work in a state that the link body4and the first and second link members5and6are ejected from the armrest body2and the user's arms are placed on the armrest member9, the weight of the arm applied to the armrest member9is applied to both the second link member6and the first link member5. Therefore, the upper cylinders81and71of the second pin member8and the first pin member7are lowered and release the balls85and76from the control grooves84and74, so that the second link member6and the first link member5become a freely rotatable state. Therefore, the computer user freely moves in a state that the user's arms are placed on the armrest member9and performs a computer work as shown inFIGS. 10 and 13.

When the user removes his arms from the armrest member9in a state that the armrest member9is maintained for performing another work while the user performs a computer work in a state that the user places his arms on the armrest member9or when the user is moved out of the chair, no load is applied to the armrest member9. Therefore, the upper cylinders71and81are upwardly moved by the elastic force that the support springs73and83of the first pin member7and the second pin member8are returned to their original states, so that the control grooves74and84are exposed, and the balls76and85which are elastically supported by the ball springs75and86elastically support the control grooves74and84. Therefore, the rotation operations of the first and second link members5and6are controlled by the balls76and85which elastically support the control grooves74and84, so that the armrest member9is maintained at the position in which the user performs a computer work as shown inFIGS. 9 and 12.

When the armrest apparatus which is ejected from the armrest body2installed in the chair1and stably supports the user's arms during a computer work is received into the armrest body2, the first link member5is slide-inserted into the sliding space45of the link body4, and the upper end of the inner rod32of the lifting and lowering guide member3protruded in the sliding space54of the link body4receives a pressing pressure by the slanted surface53formed in the lower surface of the rear end portion5bof the second link member5, so that the inner rod32is lowered by the height of the slanted surface as shown in FIG.7. When the inner rod32is lowered by the slanted surface53, the lowering protrusion322pushes the lowering control pin25which is engaged to the lowering control hole312as shown inFIG. 6, and the lifting and lowering guide member3becomes operable, and the computer user holds the armrest member9and pushes the link body4in the direction of the upper receiving space21of the armrest body2. Therefore, the lifting and lowering guide member3elastically presses the main spring35and is received into the lifting and lowering guide space22. In addition, the link body4is received in the upper receiving space21, and the armrest member9is placed on the upper surface of the armrest body2.

When the lowering and embedding operation of the lifting and lowering guide member3into the lifting and lowering guide space22is completed, the lifting control pin24is elastically inserted into the lifting control hole311for thereby controlling the lifting operation of the lifting and lowering guide member3as shown in FIG.5. Since the pressing surface54formed in the lower surface of the rear end portion5bof the second link member5received in the sliding space45of the link body4presses the upper portion of the inner rod32of the lifting and lowering guide member3, the lifting and lowering guide member3, the link body4and the first and second link members5and6are stably inserted into the interior of the armrest body2. In addition, the armrest member9is closely contacted with the upper surface of the armrest body2for thereby stably supporting the user's arms.

When the link body4is received in the upper receiving space21of the armrest body2, the elastic support member27elastically installed in the front portion of the upper receiving space21elastically pushes the rotation end6aof the second link member6, and a pulling force is generated between the permanent magnet61installed in the free end6aof the second link member6and the permanent magnet46embedded in the upper link41of the link body4, so that the first and second link members5and6are not escaped from the link body4. The permanent magnet47embedded in the inner end portion of the sliding space45of the link body4pulls the permanent magnet55embedded in the rear end portion5bof the first link member5.

Therefore, the link body4received in the upper receiving space21of the armrest body2, the first link member5inserted in the sliding space45of the link body and the second link member6installed in parallel with the upper surface of the upper link41are stably received in the upper receiving space21together with the link body4by the magnetic force of each permanent magnet and the elastic supporting force of the elastic supporting member27.

As described above, in the present invention, the chair according to the present invention is used as a common chair at a usual time in such a manner that the armrest body having the armrest member is installed at both sides of the seat of the chair as an armrest. When the chair according to the present invention is used for a computer work, the user who sits on the chair ejects the armrest apparatus from the armrest body installed at both sides of the chair and places his arms on the armrest member which is freely movable in a horizontal direction for thereby enhancing a workability of a computer work. When the user lifts his arms from the armrest member for performing another work during a certain computer work using the armrest apparatus or the user is moved out of the chair, the first and second link members connected to the link body of the armrest apparatus are not freely moved, but maintains its current state by the stopper mechanism formed on the ball and springs, so that the user fast restarts his work from the previous state work for thereby saving the working time and enhancing a convenience. In particular, in the present invention, the user's arms are stably supported at a certain height at which the user easily handles the keyboard and mouse of the computer, so that it is possible to decrease the fatigue of the user's arms. In addition, the user can perform a computer work in a right posture in the chair, so that it is possible to prevent a computer related symptom.