Lifting table with height adjustment device

Abstract

A lifting table includes a top plate height adjustment device that performs a height adjustment of all support columns in a synchronized manner. The top plate is supported on the floor by of a leg structure provided with multiple support columns arranged in parallel. Top plate receiving structures attach a column to the top plate and change the length of the support columns. Push valves exposed on the inside of the top plate receiving structures are actuated, changing the length of gas springs provided inside of the support columns. By extending an operation rod unit into the top plate receiving structures from a single handle of an operation lever via a connection fitting, the push valves are operated the same amount and at the same time in all of the columns with a single operation, so that it is possible to smoothly raise and lower the top plate.

Claims

1. A lifting table provided with top plate height adjustment device, which comprises a top plate, and a leg structure with multiple support columns mutually arranged in parallel for supporting said top plate relative to the floor, characterized in that said each support column has a length-changeable gas spring installed therein and is attached to said top plate via a top plate receiving structure; said each gas spring has a push valve for changing a length of said support column exposed on an inside of said top plate receiving structure, said push valve operated by an operation lever to change the length of said support column, thus adjusting a height of said top plate from the floor; said operation lever comprises a single handle and operation rod units that extend respectively and individually to said all top plate receiving structures from said single handle; said all operation rod units or all the remaining said operation rod units except for one operation rod unit include multiple rod sections which are connected by connectors respectively; said each rod section extending to the inside of said top plate receiving structure has gas spring operation portion on its tip end for operating said push valve; said support columns for supporting said top plate consist of three support columns; said operation lever has two said operation rod units in order to operate gas springs installed in left and right support columns, each of said operation rod units includes, as multiple rods, a first rod section that extends horizontally from said handle, and a second rod section that extends along a direction perpendicular to said first rod section to the inside of the top plate receiving structure and has said gas spring operation portion on its tip end; said connectors are two L-shaped connectors which connect said first rod sections and said second rod sections respectively, so as to form two units each including said first rod section and said second rod section; said operation lever has also another one rod unit in order to operate a third gas spring installed in a column located in the central position, said another one rod unit is a third rod section that extends to the inside of said top plate receiving structure from said handle and has the gas spring operation portion on its tip end.

2. The lifting table provided with top plate height adjustment device according to claim 1, wherein said all top plate receiving structures comprise three top plate receiving structures, wherein said top plate is a rectangle top plate that is longer in lateral direction, two of said three top plate receiving structures are set closer to one lateral long side of said top plate than a remaining one top plate receiving structure, and the two of said three top plate receiving structures are arranged in a longitudinal direction respectively, the remaining one top plate receiving structure is set so as to form an isosceles triangle with said two of said three top plate receiving structures; with respect to said operation lever, said third rod section extends directly from said handle and intersects in a direction perpendicular to said one lateral long side edge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIGS. 1A, 1B, 1C, 1D and 1E are views of the first embodiment of a lifting table provided with a height adjustment device according to the present invention.

(2) FIGS. 2A and 2B are detail views of an operation lever of the height adjustment device mounted on the lifting table shown in FIG. 1.

(3) FIG. 3 is a perspective view of the second embodiment of a lifting table with height adjustment device according to the present invention.

(4) FIG. 4 is a perspective view of the third embodiment of a lifting table with height adjustment device according to the present invention.

(5) FIG. 5 is a perspective view of the fourth embodiment of a lifting table with height adjustment device according to the present invention.

(6) FIG. 6 is a perspective view of the fifth embodiment of a lifting table with height adjustment device according to the present invention.

(7) FIGS. 7A, 7B and 7C are perspective views of the sixth embodiment of a lifting table with height adjustment device according to the present invention.

(8) FIGS. 8A, 8B and 8C are perspective views of the seventh embodiment of a lifting table with height adjustment device according to the present invention.

DETAILED DESCRIPTION

(9) Referring now to the embodiments of the invention shown in the attached drawings, FIGS. 1A-1E show the first embodiment of a lifting table with height adjustment device according to the present invention, and FIGS. 2A and 2B the details of the operation lever of the height adjustment device mounted on the lifting table shown in FIGS. 1A-1E.

(10) The first embodiment of a lifting table with the height adjustment device (hereinafter referred to as “lifting table”) is shown in FIGS. 1A-1E; FIG. 1A is a perspective view of the lifting table, FIG. 1B is a front view of the lifting table, FIG. 1C is a side view of the lifting table, FIG. 1D is a top view of the lifting table and FIG. 1E is an enlarged view of the part encircled with circle E in FIG. 1B. The lifting table 1 comprises the top plate 2 and the table leg structure 3 supporting the top plate 2. The top plate 2 in the first embodiment is made of transparent glass, those in other embodiments are same, so that the table leg structure 3 can be seen through the top plate 2. The top plate 2 may be made of wood, resin, metal or other materials, and of course may be made of nontransparent materials.

(11) The top plate 2 in the first embodiment is of rectangle plate which is the most common in office table or working platform. The table leg structure 3 comprises a H-shaped base leg body 4, and two support columns 5, 5 which are placed on the base leg body 4 for supporting the top plate 2. The base leg body 4 includes side leg portions 6, 6 placed in the long side direction of top plate 2 and a central leg portion 7 which connects two side leg portions 6, 6 together in central part. Supporting feet 8, 8 are mounted on the lower surfaces of the front and rear ends of each side leg portion 6. In the lifting table 1, the top plate 2 is stably supported on the floor with four support feet 8 which are set on the floor of same or smaller area than that of top plate 2 through the support columns 5, 5 and the H-shaped base leg body 4. It is also allowed to install small casters with locking function on the support feet 8 so that the lifting table 1 could move on the floor.

(12) Each support column 5 comprises inner and outer cylinders which are telescopically engaged each other (outer cylinder 11 and inner cylinder 12 as air spring shield), a gas spring 13 is provided inside the inner cylinder 12. The outer cylinder 11 and the inner cylinder 12 may slide relatively along the longitudinal direction (the vertical direction in case of set up type) by means of sliding mechanism with longitudinal concave grooves and convex lines which is provided on a cap or a shield of upper end of outer cylinder 11. Although it is not indicated on the drawing, the lower end of the inner cylinder 12 may slide by virtue of the slider along the inner circumference surface of the outer cylinder 11. The lower end 14 of the outer cylinder 11 is supported by the central leg 7 of the base leg body 4. Receiving structure 20 (to be specified hereinafter) for supporting the top plate 2 is provided between lower surface of top plate 2 and upper end of each support column 5. The upper end 15 of inner cylinder 12 and the receiving structure 20 are made of iron or resin product like polypropylene reinforced with glass fibers, and may be fabricated in integrated form, or be assembled with parts which are fabricated separately and fixing parts like blind rivets.

(13) The air spring 13 provided inside the support column 5, which is not shown in the drawing, may be the one well known that is composed of a cylinder and the piston rod which moves in the cylinder. With regard to the air spring 13, the lower base end of the cylinder is fixed on the lower end 14 of outer cylinder 11, and the upper end of the piston rod is fixed on the upper end 15 of inner cylinder 12. The top plate 2 is supported by the receiving structures 20 directly so that the load applied on the top plate 2 would be transferred to the columns 5 through the receiving structures 20. Namely, with respect to each receiving structure 20, the load would be transferred from inner cylinder 12, and via air spring 13, outer cylinder 11, base leg body 4 and supporting feet 8, 8 to the floor. Two support columns 5, 5, including the air spring 13 and the receiving structure 20, have the same structure.

(14) For operating the air spring 13, the top end of the piston rod is fitted with one push valve 16 in the manner that it protrudes upwards from the piston rod. The push valve 16 is pushed with the operation lever 30 to control the flow of the gas in the air spring 13 so that the piston rod could move in and out of the air cylinder. With such function of the air spring 13, the inner and outer cylinders 11 and 12 could extend-retract to adjust the length of the columns 5, 5, namely the height of the top plate 2. The air pressure (5 kg, 8 kg, 10 kg or 20 kg) in the air spring 13 may be adjusted according to the weight applied on the top plate 2 of the table 1.

(15) The receiving structures 20 is composed of a central recess section 21 of a structure of substantially square dish-shape as a whole and formed in a manner surrounded by disc-form side walls and a bottom wall, and peripheral section 22 which is continuous with the recess section 21 and has a flat upper surface formed in a manner surrounding to the recess 21. The receiving structure 20 may be formed by integrating the recess 21 and peripheral section 22, or assembled with the parts which are fabricated separately and the fasteners like blind rivets etc. The receiving structure 20 is fixed on the back of the top plate 2 on appropriate position of the peripheral section 22 with appropriate fasteners 23 (only some parts are numbered) like blind rivet. The receiving structure 20 can be fixed on the top plate 2 by disposing the receiving structure 20 closely on the back of the top plate 2 and pressing the blind rivet through the peripheral section 22 into the back of the top plate 2 without protruding from the surface of the top plate 2.

(16) With respect to the gas spring 13 of the support column 5, the upper end 15 of inner cylinder 12 is connected to the receiving structure 20 in a manner running through the bottom wall of the recess 21 of the receiving structure 20. The push valve 16 of the air spring 13 penetrates through the upper end 15 of the inner cylinder 12 and is exposed in the inner space of the recess 21 of the receiving structure 20, and is disposed so as to be pushed down by the air spring operating part of the operation lever 30. The air spring 13 and the receiving structure 20 also could be combined with blind rivets.

(17) In order to operate two air springs 13, 13 in the support columns 5,5 with one operation lever, this invention utilizes an operation lever 30 of a special structure. The operation lever comprises a single handle 31 having a shape protruding toward front side so as to be convenient for the user to hold, and operation rod units 32 which extend from the handle section 31 toward all top plate receiving structures 20 individually so as to operate the air springs 13 respectively. The operation rod unit 32 includes the first rod sections 33a, 33a which extend linearly along the left and right lateral directions on both sides of the handle section 31, L-shaped connectors 34, 34, as the connectors, mounted on the top ends of the first rod sections 33a, 33a and the second rod sections 33b, 33b which extend linearly from the connectors 34, 34 in the longitudinal direction (namely in the direction orthogonal to the first rod sections 33a, 33a) into the top plate receiving structure 20. The first rod sections 33a, 33a and the seconds rod sections 33b, 33b form multiple rod sections (all of which are numbered generally as “33”) which are connected with the connectors 34, 34. The height adjustment device in the lifting table 1 includes the air springs 13, 13 which are provided inside the support columns 5, 5 and are connected to the top plate receiving structure 20,20, and the operation lever 30 which is used to operate the push valves 16, 16 of the air springs 13, 13. Each operation rod unit 32 is supported to the receiving structure 20 so as to swing with the lever fulcrum portion 35 of the second rod section 33b as a fulcrum.

(18) FIG. 2 shows the details of the operation lever for height adjustment device provided with the lifting table. FIG. 2A is the perspective view of the operation lever and the receiving structure as a whole, and FIG. 2B is the partially sectional view showing the details of the L-shaped connector. As shown in FIG. 2A (also in FIG. 1B and FIG. 1C), the structure of the operation lever 30 is to ensure the axes of the handle 31 and operation rod unit 32 including the first rod sections 33a, 33a, the connectors 34, 34 and the second rod sections 33b, 33b to be on same plane. The structure of the operation lever 30 is to ensure the axes to be on same plane so that it could reduce the structure error and the occurrence of looseness and increase the operation accuracy of the operation lever 30. Each second rod section 33b runs through the side wall of the receiving structure 20 and extends into the recess 21, and the tip end portion of each second rod section 33b in the recess 21 becomes the air spring operating portion 36 which is machined into flat form. The second rod section 33b could tilt up and down relatively to the receiving structure 20 at the lever fulcrum portion 35 in the middle of the length. When the handle 31 is held, and the operation lever 30 is swung toward the direction of the top plate 2, the air spring operating portions 36, 36 would contact with and push down the push valves 16, 16 of the air springs 13, 13 at the same time so that two air springs 13, 13 would be started.

(19) As shown in FIG. 2B, in the first rod section 33a and the second rod section 33b is formed holes 34a, 34a into which two end portions of L-shaped connector 34 may be inserted. The inner diameter of the holes 34a, 34a is sufficient for the first rod section 33a and the second rod section 33b to be inserted; sufficient gaps Ga, Gb for adjustment are reserved between the end faces of the first rod section 33a and the second rod section 33b and hole bottoms. There are opening-type screw holes 34b, 34b crossing with the holes 34a, 34a on the connector 34. The small screws 34c, 34c are screwed into the screw holes 34b, 34b so that the top ends of the small screws 34c, 34c could contact with the first rod section 33a and the second rod section 33b inserted in holes 34a, 34a, and the first rod section 33a and the second rod section 33b could be fixed on the connector 34 as per this position and attitude. For ensuring the rigidity and strength without substantial deformation under the effect of general operating force, and preventing the thread grooves of screw holes 34b, 34b from being scratched easily, the connector should be made of metals or resin products like nylon or (glass fiber reinforced) polypropylene etc. (integrated forming).

(20) In the process of fabricating the operation lever 30, would occur machining errors that handle 31 and the first rod sections 33a, 33a and the second rod sections 33b, 33b are not on the correct positions in the same plane, or the first rod sections 33a, 33a are not arranged in same straight line, or the second rod sections 33b, 33b are not parallel. In such cases, it would be very difficult to synchronize the actions of push valves 16, 16 of air springs 13, 13 merely by operating the handle section 31—i.e. it would be relatively difficult to operate at the same time and in the same amount. Besides, when fabricating the first rod sections 33a, 33a and the second rod sections 33b, 33b only with rod material rather than connectors 34, 34, it would be very difficult to ensure that the first and the second rod sections 33a,33b in one unit are in the same plane to those of in another unit. When operating the operation lever 30, it would produce big deformation like bending or twisting etc. on the bending part from the first rod section 33a to the second rod section 33b, the operation of the handle 31 of the operation lever 30 could not be transferred to the second rod sections 33b, 33b, and the push valves 16, 16 of two air springs 13, 13 could not work synchronously. In such case, it would be unable to finish the height adjustment of the top plate 2.

(21) The connector 34 used in this height adjustment device is allowed to rotate relatively around two axes to the first rod section 33a and the second rod section 33b before fixing state (rotate by 0 around the axis of the first rod section 33a and by δ around the axis of the second rod section). Besides, in same state before fixing, it may move along the axis direction X of the first rod section 33a and the axis direction Y of the second rod section within the allowable scope of the gaps Ga and Gb. For realizing such rotational motion and movement, the handle section 31 of the function lever 30 is operated after loosening the small screws 34c, 34c, and the insertion amount and angle of the first rod sections 33a, 33a and the second rod sections 33b, 33b corresponding to the connectors 34, 34 are adjusted so as to make the air spring operating portions 36, 36 on the tip ends of the second rod sections 33b, 33b contact with the push valves 16, 16 of the air springs 13, 13 (only contact, without inward pushing), and tighten the small screws 34c, 34c in this state for the purpose of fixing the first rod sections 33a, 33a and the second rod sections 33b, 33b on the connectors 34, 34 and integrating the function lever 30. The operation lever still could be assembled on the receiving structures 20, 20 in the state that the fabrication error is absorbed, even though the handle 31, the first rod sections 33a, 33a and the second rod sections 33b, 33b were not arranged accurately and parallel to each other in the process of fabrication; when the operation lever 30 is operated by the user after being assembled, the single operation of the handle 31 would not be absorbed in the mid-way but could be transferred to air spring operating portions 36, 36 of the second rod sections 33b, 33b due to the rigidity of the connectors 34, 34 against the bending and twisting deformation, so that the operations of the push valves 16, 16 of two springs 13, 13 could be synchronized—i.e. they would contact with the push valves 16, 16 at the same time and push them in the same amount.

(22) All operation rod units 32 extended into the receiving structures 20 are not of such structure utilizing the connector 34. It also may be of the structure with one operation rod unit 32 without the connector 34 extending to the receiving structure 20 (the third rod unit) directly and the rest operation rod units 32 utilizing the connectors 34. The operation rod unit 32 extending directly to the receiving structure 20 is used as the benchmark operation rod unit for other operation rod units 32 maintaining synchronous. After loosening the small screws 34c, 34c on all connectors, the operation lever 30 is operated and the third rod unit extending to the receiving structure 20 directly is made contact with the push valve 16 of the air spring 13. In this state, the insertion amount and angle of the first rod section 33a and the second rod section 33b to the connector 34 are adjusted in the operation rod unit 32 so as to make the air spring operating portion at the tip end of the second rod section 33b contact with the push valve 16 of the air spring 13 (only contact, without inward pushing). In such state, the small screws 34c, 34c in all connectors 34 are tightened to fix the first rod section 33a and the second rod section 33b on the connector 34 and the operation lever 30 is assembled in an integrated state. After assembling, the operation lever 30 is operated, then in all the operation rod units 32 including the third rod section, the amount of a single operation at the handle 31 would not be absorbed in the mid-way but could be transferred to all air spring operating portions 36, and synchronize the operations of the push valves 16 of all air springs 13.

(23) FIG. 3-FIG. 6 are the perspective views of the embodiments 2-5 of the lifting table with height adjustment device according to this Invention. In those embodiments, the lifting tables are different only on aspects of the shapes of the top plates and the table leg structures supporting the top plates. There is no substantial difference between the support columns and the receiving structures. On aspect of the operation lever, although it is changed correspondingly according to the shapes of top plate as well as the setting differences of the support columns and receiving structures, but their fundamental structures are same. Therefore, although the top plates, table leg structures and operation levers are marked with the symbols “a”-“d” for identification in the embodiments, but the details of support columns, receiving structures and operation levers are of the same structure to those of the first embodiment fundamentally, and the same symbols to those of the first embodiment are used, the detailed explanation about them is not repeated. Besides, on aspect of the connectors, as in the case of the first embodiment, when all the air spring operation portions 36 contact with the push valves 16 of the air springs 13, all the rod sections 33 may be fixed on the corresponding connectors 34 so that the single operation of the handle 31 may be transferred to individual air spring operation portion 36 but would not be absorbed in the mid-way. Therefore, the explanation about such function is not repeated.

(24) In the second embodiment shown in FIG. 3, the elements and the positions with different structures and settings from those of the first embodiment are marked with the symbol “a”. The lifting table 1a has a rectangle top plate 2a with long side on lateral direction, and the receiving structures 20, 20 are arranged in the area close to one side in the lateral length direction of said top plate 2a and are set apart along longitudinal direction. With respect to the Leg structure 3a, the central leg portion 7a is set on the side close to the side leg portions 6a, 6a according to the set positions of corresponding support columns 5, 5 of the receiving structures 20, 20. The function lever 30a has the mechanisms corresponding to the arrangement of the receiving structures 20, 20, which mechanisms include the handle 31, the connectors 34, 34 and the second rod sections 33b, 33b which are same to those of the first embodiment, in addition to the shorter first rod sections 33a, 33a. Namely, the handle 31 is set at the corresponding central location of the short longitudinal edge of the top plate 2a, the first rod section 33a extends along the short longitudinal edge of the top plate 2a and the second rod section 33b extends orthogonally to the short longitudinal edge through the connector 34. The surface of the top plate 2a is of rectangle with long side on lateral direction, which is the most common. However, the top plate receiving structures 20, 20 are close to one side in the lateral length direction of the top plate 2a and are set separately on longitudinal direction. Thus, the lifting table 1a applies to the situation that the article on the top plate 2a is tending to one side (toward the direction with top plate receiving structures 20, 20) or that the space below the top plate is to be used effectively.

(25) In the third embodiment shown in FIG. 4, the elements and the positions with different structures and settings from those of the first embodiment are marked with the symbol “b”. The lifting table 1b has a L-shaped top plate 2b with a curved inner edge on inner side, and the receiving structures 20, 20 are arranged relatively spaced apart on the left and the right sides of the top plate 2b with the curved inner edge interposed therebetween. Therefore, the receiving structures 20, 20 are tilting to the linear edges of the top plate 2b. The operation lever 30b is of a structure corresponding to the arrangement and placement of the receiving structures 20, 20, and includes the connectors 34, 34 and the second rod sections 36b, 36b (orthogonal to the first rod sections 33a, 33a) same to those of the first embodiment; but the handle 31 extends along the inner curved edge of said top plate 2b. The table leg structure 3b has a long central leg portion 7b subject to the set position of the support columns 5, 5 corresponding to the receiving structure 20, 20. This lifting table 1b is suitable for the user to seat on the chair along the inner curved edge and use the office table or working platform with the L-shaped top plate 2b being placed in the right-angle corner of a room.

(26) In the fourth embodiment shown in FIG. 5, the elements and the positions with different structures and settings from those of the first embodiment are marked with the symbol “c”. The lifting table 1c has a fan-shaped top plate 2c, and the receiving structures 20, 20 are arranged relatively spaced apart on left side and the right side along the chord direction of the fan-arc edge of the fan-shaped top plate 2c. Thus, the receiving structures 20, 20 are set tilting to the linear edge sections of the top plate 2c. The operation lever 30c is of a structure corresponding to the arrangement and placement of the receiving structures 20, 20, the handle section 31 is set along the fan-arc edge of the top plate 2c and includes the first rod sections 33a, 33a, connectors 34, 34 and the second rod sections 33b, 33b similar to the first embodiment. The first rod sections 33a, 33a extend along the direction parallel to the chord direction of the fan-arc edge, and the second rod sections 33b, 33b extend orthogonally to the first rod sections 33a, 33a through the L-shaped connectors 34, 34. The table leg structure 3c has side leg portions 6c, 6c and a central leg portion 7c as in the case of the first embodiment, subject to the set position of the support columns 5, 5 corresponding to the receiving structure 20, 20. This lifting table 1b is suitable for the user to seat on the chair along the fan-arc edge and use the office table or working platform with the L-shaped top plate 2b being placed in the right-angle corner of a room. Besides, four lifting tables 1c could be combined into one round table. The height of the top plate 2c could be adjusted according to the situation of the people seating around the round table.

(27) In the fifth embodiment shown in FIG. 6, the elements and the positions with different structures and settings from those of the first embodiment are marked with the symbol “d”. The lifting table 1d has a rectangle top plate 2d with long side on lateral direction and three top plate receiving structures 20. In those three top plate receiving structures, the left and the right receiving structure 20, 20 are close to the long lateral side of the top plate 2d and set separately, and the remaining one receiving structure 20 is set separately from the aforesaid two so as to form a isosceles triangle, those three receiving structures 20 support the top plate 2d in a wide range. With regard to the operation lever 30d, as the operation rod units 32, in addition to the first rod sections 33a, 33a, the connectors 34, 34 and the second rod sections 33b, 33b in symmetry, the third longitudinal rod section 33d extends from the handle 31, orthogonally to the long lateral edge and directly into the top plate receiving structure 20. Besides, with respect to the structure of the base leg body 4d of the table leg structure 3d, the side leg portions 6d, 6d are longer while the central leg portion 7d is shorter. According to the area of the top plate 2d, four supporting legs 8 are set separately and support the top plate 2d stably on the floor. Thus, the top plate 2d of the lifting table 1d has a wide area and could bear the heavy articles. It is very suitable for big tables.

(28) FIGS. 7A-7C are perspective views of the sixth embodiment of the lifting table with height adjustment device according to this Invention. FIG. 7A is the overall perspective view of the lifting table, FIG. 7B is the left side view of the lifting table and FIG. 7C is the enlarged view of the part indicated with F in the FIG. 7B. The biggest difference in this embodiment from the fifth embodiment shown in FIG. 6 is that the operation lever is not of swinging type but is of lateral sliding type. However, the shapes and the structures of the top plates and the table leg structures of the lifting table are not different substantially including those three support columns 5. Therefore, the top plates, table leg structures and the operation levers are marked with the symbol “e” for identification; the details of the support columns 5, receiving structures 20 and the operation levers are fundamentally same to those of the fifth embodiment, and are marked with same symbols, so that the detailed description will not be repeated.

(29) With respect to the lifting table 1e of the sixth embodiment, the operation lever 30e is not of swinging type operated to swing in a manner of approaching the back surface of the top plate 2e but of sliding type operated to move along the back surface of the top plate 2e as shown in FIG. 7A and FIG. 7B. In other words, the operation lever 30e is composed of the first rod sections 33a, 33a extended from the left and the right of the handle 31, as two operation rod units 32, 32, and the L-shaped connectors 34, 34 which are connected to the tip ends of the handle 31. The second rod sections 33b, 33b are connected to the connectors 34, 34 along the direction orthogonal to the first rod sections 33a, 33a (the direction parallel to the top plate 2e). The second rod sections 33b, 33b bends upwards directly to approach the top plate 2e, bends again to get parallel to the top plate 2e and extends into corresponding receiving structures 20, 20 under the guidance of the guiding devices 35e, 35e. In addition to the first rod sections 33a, 33a, the operation lever 30e also includes the third rod section 33e which extends directly into the top plate receiving structure 20 provided in the center back of the top plate as the third operation rod 32. The third rod section 33e extends from the handle 31 and orthogonally to the long lateral edge and in the direction parallel to the top plate 2e before bending upwards directly to approach the top plate 2e; then, it bends again until being parallel to the top plate 2e, and extends into the corresponding receiving structure 20 in center back under the guidance of the third guiding device 35e.

(30) The second rod sections 33b, 33b and the third rod section 33e have air spring operation portions 36e with tapered surfaces 36t formed at the tip ends respectively in the corresponding receiving structure 20. The handle 31 of the operation lever 30e is hold, and is pushed in the direction along the back surface of the top plate 2e, the second rod sections 33b, 33b and the third rod section 33e will be guided by the guiding device 35e respectively, the air spring operation portions 36e at the tip end will push the push valves 16 of the air springs 13 with its tapered surface 36t, and operate synchronously. The connectors 34, 34 operate with same function as those of the connectors in the fifth embodiment so that the detailed description will not be repeated.

(31) FIGS. 7A-7C are schematic views of the seventh embodiment of the lifting table with height adjustment device according to this Invention. FIG. 8A is the front view of the lifting table, FIG. 8B is the side view of the lifting table and FIG. 8C is the side view of the lifting table. The biggest difference in this embodiment from the fifth embodiment shown in FIG. 6 is that the three support columns 5 are arranged in a straight line along the long side direction in the center so that the load on big table could be supported evenly. However, the shapes and the structures of the top plates and the table leg structure of the lifting table are not different substantially including those three support columns 5. Therefore, the top plates, table leg structure and the operation levers are marked with the symbol “f” for identification; the details of the support columns 5, receiving structures 20 and the operation levers are fundamentally same to those of the fifth embodiment, and are marked with same symbols, so that the detailed description will not be repeated.

(32) In the seventh embodiment, with regard to the three support columns 5 supporting the top plate 2f, the handle and the three operation rod units 32 are connected by the connectors interposed between their connecting portions. In other words, in the seventh embodiment, the handle 31f also serves as the T-shaped connector. With respect to the operation rod units 32, 32 extended from the handle (T-shaped connector) 31f in the left and the right direction, the handle 31f is connected to the first rod sections 33a, 33a, and the handle 31f is also connected to the third rod section 33f from the center in a manner orthogonal to the first rod sections 33a, 33a. The third rod section 33f is connected to the handle section 31f in the same way to the connector 34, which allows the rod section rotate around the axis and move along the axis direction. The first rod sections 33a, 33a also may be connected to the handle section 31f in the same way to the third rod section 33f. In the state that the air spring operation portions 36 provided at the tip ends of the second rod sections 33b, 33b and the third rod section 33f contact with the push valves 16 of all air springs 13, the small screws are screwed into the connectors 31f, 34, 34 so that the operation lever 30f will be integrated. Then, all the air spring operation portions 36 in the individual receiving structure 20 could push the push valves 16 to realize the synchronized movements of all air springs 13 by operating the handle 31f.

(33) For the convenience of assembling and disassembling, the top plate 2 of table 1 and table leg structure 3 should be of assembly type and be fitted with fixing parts which could be disassembled. When assembly type lifting table is utilized, the lifting table with height adjustment device according to this Invention may be applied to the existing tables, television bench, writing desk or other articles with lifting function. Besides, the receiving structure 20 and the table leg structure 3 may be of embedded resin structure or be made of aluminum or iron etc. for the purpose of ensuring the function and improving the strength of the air spring support. They shall be fabricated with the materials selected according to the required strength and used flexibly according to the purposes etc. As a production example, in the case of mainly resin, there can be mentioned pp (polypropylene) to which glass fiber, nylon, aluminum and iron are added. In addition, the table legs (wood, iron or stainless steel products) may be inserted into the air spring receiving structures as general table legs. After the table legs are inserted into the air spring receiving structure made of resin, they also may be fixed with fastening screws.

(34) TABLE-US-00001 1. lifting table 2. top plate 3. table leg structure 4. base leg body 5. support column 6. side leg 7. central leg portion 8. supporting foot 11. outer cylinder 12. inner cylinder 13. air spring 14. lower end section of outer cylinder 11 15. upper end section of inner cylinder 12 (bearing section) 16. push valve 20. receiving structure 21.recess 22. peripheral section 23. fixing part 30. operation lever 31. handle 32. operation rod unit 33. rod section 33a. first rod section 33b. second rod section 34. connector 34a. hole 34b. screw hole 34c. small screw 35. lever fulcrum 35e. guiding device 36, 36e. air spring operation portion 36t. tapered surface Ga, Gb. Gaps X, Y directions θ, δ angles