Expandable column for X-ray equipment

Abstract

The telescopic column for the X-ray imaging device includes a main column, a sub-column installed on one side of the main column so as to be able to rise and fall, and a weight compensation unit installed on the other side of the main column to compensate for the weight of the sub-column, the weight compensation unit including a cam formed so that a winding radius of a wire changes according to a lift height of the sub-column, and an elastic member that expands and contracts according to rotation of the cam and provides an elastic force to compensate for the weight of the sub-column.

Description

[Technical field]

[0001] The present invention relates to an extendable column for an X-ray imaging device that can be easily raised and lowered with a uniform force. [Background technology]

[0002] Recently, when X-rays are required for seriously ill patients who are difficult to move around in or during surgery, the patient does not go directly to the X-ray room, but instead moves the mobile X-ray device to the required location to take the X-ray. Examples of the mobile X-ray device are disclosed in KR10-2011-0062397A and KR10-2012-0095460A.

[0003] 1 is a diagram showing the configuration of a conventional mobile X-ray imaging device. The mobile X-ray imaging device includes a main body 1 on which a display 27 is mounted, a column 2 installed perpendicular to the main body 1, an arm 3 attached to the column 2, and an X-ray source 4 provided on the arm 3. The column 2 may include a main column 5 and a sub-column 6, and the arm 3 may include a plurality of unit arms 7, 8, 9 that can be extended and retracted in multiple stages. The lengths of the column 2 and the arm 3 can be shortened for safety during movement, and the lengths of the column 2 and the arm 3 can be extended to position the X-ray source 4 at an appropriate position during imaging.

[0004] Conventional mobile X-ray imaging devices are equipped with a separate driving source for extending or shortening the length (height) of the column 2, but since the column 2 cannot move quickly, it is difficult to position the X-ray source 4 at a location desired by the user within a short period of time.

[0005] As another example, a weight is used to compensate for the weight of the arm 3 and the sub-column 6 so that the length of the column 2 can be manually extended or shortened and the sub-column 6 together with the arm 3 can be raised and lowered with a small amount of force. However, when compensating for weight using a weight, the overall weight of the mobile X-ray imaging device increases, which causes a problem of reduced mobility. Summary of the Invention [Problem to be solved by the invention]

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an extendable column for an X-ray imaging device that can be manually positioned at a desired location quickly and easily without the need for a separate driving source or weight.

[0007] Another object of the present invention is to provide an expandable column for an X-ray imaging device, which can compensate for the weight of an arm and a sub-column by using the elastic force of an elastic member.

[0008] Another object of the present invention is to provide an extendable column for an X-ray imaging device that can raise and lower an arm and a sub-column with a uniform force, regardless of changes in the elastic force of an elastic member according to the lift height of the arm and the sub-column. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, there is provided an expandable column for an X-ray imaging device, comprising: a main column; a sub-column installed on one side of the main column so as to be able to rise and fall; and a weight compensation part installed on the other side of the main column to compensate for the weight of the sub-column, the weight compensation part including a cam formed so that a winding radius of a wire changes according to a rise and fall height of the sub-column, and an elastic member that expands and contracts according to rotation of the cam to provide an elastic force to compensate for the weight of the sub-column.

[0010] According to one feature, the weight compensation unit may include a first fixed pulley installed on the main column, a movable pulley installed to be movable up and down relative to the first fixed pulley, a first wire having one end connected to the main column and the other end connected to the sub-column via the movable pulley and the first fixed pulley, a cam unit installed to rotate in conjunction with the elevation and lowering of the movable pulley, and an elastic member that expands and contracts in conjunction with the rotation of the cam unit to provide an elastic force to the sub-column.

[0011] According to another feature, the weight compensation part may include a second wire having one end connected to one side of the movable pulley and the other end wound around one side of the cam unit, and a third wire having one end connected to the elastic member and the other end wound around the other side of the cam unit.

[0012] According to another feature, the cam unit may include a cam formed to change a winding radius of the second wire when rotated, and a cam pulley installed on one side of the cam to rotate integrally with the cam, around which the third wire is wound.

[0013] According to another feature, the torque of the cam corresponding to the vertical movement of the moving pulley can act as a reaction torque against the torque of the cam pulley corresponding to the expansion and contraction of the elastic member.

[0014] According to another aspect, the sub-column may include a first sub-column installed on one side of the main column to be movable up and down, and a second sub-column installed on one side of the first sub-column to be movable up and down.

[0015] According to another feature, the system may further include a linkage mechanism for causing the second sub-column to rise and fall in conjunction with the rise and fall of the first sub-column, and the linkage mechanism may include a second fixed pulley installed at an upper end of the first sub-column, and a fourth wire having one end coupled to the main column and the other end coupled to the second sub-column via the second fixed pulley.

[0016] According to another feature, the weight compensation part may include a third fixed pulley installed on one side of the elastic member, and the second wire may be wound around one side of the cam unit via the third fixed pulley.

[0017] According to another feature, the sub-column may include a first sub-column installed on one side of the main column to be able to rise and fall, and a second sub-column installed on one side of the first sub-column to be able to rise and fall, and may further include a linkage mechanism for causing the second sub-column to rise and fall in conjunction with the rise and fall of the first sub-column, and the linkage mechanism may include a fourth fixed pulley installed on an upper end of the first sub-column, and a fourth wire having one end coupled to one side of the main column and the other end coupled to one side of the second sub-column via the fourth fixed pulley. Effect of the Invention

[0018] According to the telescopic column for X-ray imaging equipment of the present invention, the length of the column can be extended or shortened manually, quickly and easily, by compensating for the weight of the arm and the sub-column using the elastic force of the elastic member, without a separate driving source or weight. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a diagram showing the configuration of a conventional mobile X-ray imaging device. [Diagram 2] FIG. 1 is a configuration diagram of an expandable column for an X-ray imaging apparatus according to a first embodiment of the present invention. [Diagram 3] FIG. 1 is a configuration diagram of an expandable column for an X-ray imaging apparatus according to a first embodiment of the present invention. [Figure 4] 3 is a cam profile calculated according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a side view of the cam according to the first embodiment of the present invention. [Figure 6] FIG. 1 is a perspective view of a telescopic column according to a first embodiment of the present invention. [Figure 7] FIG. 1 is a perspective view of a telescopic column according to a first embodiment of the present invention. [Figure 8] FIG. 2 is a side view of the telescopic column according to the first embodiment of the present invention. [Figure 9] FIG. 2 is a front view of the telescopic column according to the first embodiment of the present invention. [Figure 10] FIG. 2 is a rear view of the telescopic column according to the first embodiment of the present invention. [Figure 11]FIG. 4 is a partial enlarged view showing a sliding connection between a main column and a first sub-column according to the first embodiment of the present invention. [Figure 12] FIG. 4 is a partial enlarged view showing sliding coupling between a first sub-column and a second sub-column according to the first embodiment of the present invention. [Figure 13] FIG. 2 is a partial enlarged view of a main column showing a weight compensation portion according to the first embodiment of the present invention. [Figure 14] FIG. 2 is an exploded perspective view of a cam unit according to the first embodiment of the present invention. [Figure 15] FIG. 5 is a configuration diagram of an expandable column for an X-ray imaging apparatus according to a second embodiment of the present invention. [Figure 16] FIG. 5 is a configuration diagram of an expandable column for an X-ray imaging apparatus according to a second embodiment of the present invention. [Figure 17] FIG. 5 is a perspective view of a telescopic column according to a second embodiment of the present invention. [Figure 18] FIG. 5 is a perspective view of a telescopic column according to a second embodiment of the present invention. [Figure 19] FIG. 6 is a side view of a telescopic column according to a second embodiment of the present invention. [Figure 20] FIG. 6 is a front view of a telescopic column according to a second embodiment of the present invention. [Figure 21] FIG. 6 is a rear view of a telescoping column according to a second embodiment of the present invention. [Figure 22] FIG. 11 is a partial enlarged view showing a sliding connection between a main column and a first sub-column according to a second embodiment of the present invention. [Diagram 23] FIG. 11 is a partial enlarged view showing sliding coupling between a first sub-column and a second sub-column according to a second embodiment of the present invention. [Figure 24] FIG. 11 is a partial enlarged view of a main column showing a weight compensation portion according to a second embodiment of the present invention. [Diagram 25] FIG. 11 is a perspective view of a cam unit according to a second embodiment of the present invention. [Figure 26] FIG. 11 is a partial enlarged view of a first wire connecting a main column and a first sub-column according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments described below are merely for the purpose of explaining the invention in detail to the extent that a person having ordinary skill in the art to which the present invention belongs can easily carry out the invention, and are not intended to limit the scope of protection of the present invention. In addition, in describing various embodiments of the present invention, the same reference numerals are used for components having the same technical features.

[0021] The telescopic column for an X-ray imaging device according to the present invention includes a main column, a sub-column installed to be movable relative to the main column, and a weight compensation unit that compensates for the weight of the sub-column so that a user can easily move the sub-column up and down with a small force. In addition, the weight compensation unit includes a cam unit having a cam and a cam pulley so that the sub-column can be moved up and down with a uniform force regardless of changes in the lift height of the sub-column. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0022] 2 to 14 are views showing an expandable column for an X-ray imaging apparatus according to a first embodiment of the present invention.

[0023] As shown in FIGS. 2 and 3, the telescopic column 100 for an X-ray imaging apparatus includes a main column 200, a sub-column 300 that is installed so as to be movable up and down relative to the main column 200, and a weight compensation unit 400 that compensates for the weight of the sub-column 300.

[0024] The weight compensation unit 400 includes a first fixed pulley 410 and a movable pulley 420 installed in the main column 200, a first wire 430 connecting the main column 200 and the sub-column 300, a cam 450 in which the winding radius of a second wire 480 connected to the movable pulley 420 changes depending on the elevation height of the sub-column 300, and an elastic member 470 that expands and contracts in response to the rotation of the cam 450 and provides an elastic force to the sub-column 300 through a third wire 490.

[0025] According to the first embodiment of the present invention, the weight of the sub-column 300 is compensated for by the weight compensation unit 400, so that a user can easily raise and lower the sub-column 300 at a constant speed even with a small force. In addition, the weight compensation unit 400 applies a uniform force regardless of the height of the sub-column 300 when raising and lowering the sub-column 300, so that the sub-column 300 can be raised and lowered at a constant speed.

[0026] The main column 200 is installed vertically on the body (1, see FIG. 1) of the mobile X-ray imaging device, and a space is formed inside so that a weight compensation unit 400 including a number of pulleys and wires can be installed. At this time, the main column 200 can be installed on the body 1 of the mobile X-ray imaging device so as to be rotatable about an axis.

[0027] The sub-column 300 is installed to be movable up and down on one side of the main column 200. For example, a slide rail (not shown) may be formed on one side of the main column 200, and the sub-column 300 may be provided with a number of rollers (not shown) to slide up and down along the slide rail of the main column 200.

[0028] In addition, an arm (3, see FIG. 1) having an X-ray source (4, see FIG. 1) at its end may be installed on one side of the sub-column 300 so as to be movable up and down. In this case, the arm may be formed so as to be capable of multi-stage extension and contraction, and a weight compensation unit 400 compensates for the weight of the sub-column 300 including the X-ray source 4 and the arm 3.

[0029] The weight compensation unit 400 may include a first fixed pulley 410 rotatably installed at the lower end of the main column 200, a movable pulley 420 spaced apart from the upper part of the first fixed pulley 410 and movable up and down, and a first wire 430 connecting the main column 200 and the sub-column 300 via the first fixed pulley 410 and the movable pulley 420.

[0030] At this time, the number of the first fixed pulleys 410 and the movable pulleys 420 may be appropriately selected according to need. As an example, a pair of movable pulleys 420 may be installed side by side on top of one first fixed pulley 410. One end of the first wire 430 may be coupled to one side of the main column 200, and the other end may be coupled to the sub-column 300 after being wound around the movable pulley 420 and the first fixed pulley 410.

[0031] A first wire 430 connects the main column 200 and the sub-column 300 via a first fixed pulley 410 and a movable pulley 420, so that when the sub-column 300 moves up and down relative to the main column 200, the movable pulley 420 moves up and down relative to the first fixed pulley 410.

[0032] At this time, the sub-column 300 is manually raised and lowered by a user, and the weight compensation unit 400 serves to easily raise and lower the sub-column 300 at a constant speed with little force despite the weight of the sub-column 300.

[0033] For this reason, an elastic member 470 that provides an elastic force to the sub-column 300 is installed in the space of the main column 200. The elastic member 470 is installed to expand and contract in conjunction with the elevation and lowering of the moving pulley 420, and compensates for the weight of the sub-column 300 by providing an elastic force to the sub-column 300 together with the moving pulley 420. For example, when the elastic force provided by the elastic member 470 is balanced with the weight of the sub-column 300, the user can easily raise and lower the sub-column 300 at a constant speed with little force.

[0034] Although the drawings show an expandable tension spring as an example of the elastic member 470, this is only one embodiment, and various types of elastic member 470 that provide elastic force, such as a gas spring or a torsion spring, can be used as needed.

[0035] In addition, the elastic force provided by the elastic member 470 may change according to the elevation and lowering of the sub-column 300. For example, when a tension spring is used as the elastic member 470, the tension spring gradually expands as the sub-column 300 is lowered, increasing the elastic force, and therefore the force required by the user to lower the sub-column also gradually increases.

[0036] According to the first embodiment of the present invention, the cam unit 440 is provided so that the sub-column 300 can be raised and lowered with a uniform force regardless of the change in the lift height of the sub-column 300.

[0037] The cam unit 440 may be installed to rotate in conjunction with the elevation of the movable pulley 420. For example, one end of the second wire 480 may be coupled to one side of the movable pulley 420, and the other end may be wound around one side of the cam unit 440.

[0038] In addition, the elastic member 470 may be installed to expand and contract in conjunction with the rotation of the cam unit 440. For example, one end of the third wire 490 may be coupled to the elastic member 470, and the other end may be coupled to the other side of the cam unit 440.

[0039] More specifically, the cam unit 440 includes a cam 450 formed such that the winding radius of the second wire 480 changes when the cam unit 440 rotates, and a cam pulley 460 installed on one side of the cam 450 to rotate together with the cam 450 and around which the third wire 490 is wound. As an example, a pair of cam pulleys 460 are installed on both sides of the cam 450, and a pair of third wires 490 extending side by side from an upper end of the elastic member 470 may be wound around the pair of cam pulleys 460, respectively.

[0040] In this case, when the sub-column 300 rises, the tension spring is compressed, and the cam pulley 460 rotates to loosen the third wire 490. At this time, the cam 450 rotates together with the cam pulley 460, so that the second wire 480 is wound around the cam 450, and the second wire 480 pulls the movable pulley 420 upward, so that the movable pulley 420 moves to above the first fixed pulley 410.

[0041] Conversely, when the sub-column 300 descends, the movable pulley 420 descends together with the sub-column 300, and the cam 450 rotates to loosen the second wire 480. At this time, the cam pulley 460 rotates together with the cam 450, causing the third wire 490 to be wound around the cam pulley 460, and the tension spring is stretched by the third wire 490.

[0042] Here, a cam profile is formed in the cam 450 so that the winding radius of the second wire 480 changes when the cam 450 rotates. This is to allow the torque of the cam pulley 460 according to the expansion and contraction of the elastic member 470 and the torque of the cam 450 according to the elevation and lowering of the movable pulley 420 to act as a mutual reaction torque, so that the sub-column 300 can be raised and lowered with a uniform force regardless of the height of the sub-column 300.

[0043] FIG. 4 is a graph showing a cam profile according to the first embodiment of the present invention, which is obtained by calculating the spring force of the tension spring and the torque of cam pulley 460 according to the rotation angle of cam pulley 460, and then calculating the radius of cam 450 from the torque of cam 450 to compensate for this.

[0044] 5, the cam 450 has a shaft hole 451 for inserting a rotating shaft on one side, and has a shape in which the radius gradually increases in one direction along the circumferential direction within a predetermined angular section. Also, the cam 450 has a curved surface 452 formed in a spiral shape within a predetermined angular section corresponding to the ascending / descending section of the sub-column 300 as a whole, and a straight surface 453 formed in the direction of the rotating shaft at one end of the spiral curved surface 452. Furthermore, a second wire fixing part (454, not shown in FIG. 5 but shown in FIG. 14) to which the other end of the second wire 480 is fixed is formed on one side of the straight surface 453, and a first winding groove (456, not shown in FIG. 5 but shown in FIG. 14) for winding the second wire 480 is formed on the spiral curved surface 452 of the cam 450.

[0045] Therefore, when the sub-column 300 descends, the tension spring expands and the torque of the cam pulley 460 increases, and the winding radius of the second wire 480 of the cam 450 gradually increases, increasing the torque of the cam 450. Conversely, when the sub-column 300 ascends, the tension spring contracts and the torque of the cam pulley 460 decreases, and the winding radius of the second wire 480 of the cam 450 gradually decreases, decreasing the torque of the cam 450.

[0046] At this time, the torque of the cam 450 acts as a reaction torque against the torque of the cam pulley 460 to compensate for the difference in the elastic force of the tension spring and the weight of the sub-column 300, allowing the user to raise and lower the sub-column 300 with a uniform force regardless of the height of the sub-column 300 or the extension length of the tension spring.

[0047] The telescopic column 100 for the X-ray imaging device includes a main column 200, a sub-column 300 that is installed on one side of the main column 200 so as to be able to move up and down, and a weight compensation unit 400 that is installed on the main column 200 and compensates for the weight of the sub-column 300, which can be understood in more detail with reference to Figures 6 to 10.

[0048] A support plate 210 for supporting the main column 200 is connected to the lower end of the main column 200, and the support plate 210 may be connected to the body 1 of the mobile X-ray imaging device. Although a rectangular support plate 210 is shown in the drawings, this is only one example, and a circular support plate 210 may also be rotatably connected to the body 1 of the mobile X-ray imaging device.

[0049] The main column 200 includes a pair of main frames 220 vertically installed at a predetermined distance apart in the width direction of the support plate 210, an upper frame 230 coupled to the upper ends of the pair of main frames 220, a support frame 240 installed in parallel with the main frames 220 at a predetermined distance apart behind the main frames 220, and a coupling frame 250 coupling the upper ends of the support frames 240 to the rear ends of the main frames 220. As an example, the coupling frame 250 is formed by coupling four unit frames in a rectangular shape.

[0050] The main frame 220 serves to guide the sub-column 300 in the ascending and descending direction, and a number of pulleys and cam units 440 and elastic members 470 constituting the weight compensation part 400 are installed in the space between the main frame 220 and the support frame 240 .

[0051] The sub-column 300 includes a first sub-column 310 installed on one side of the main column 200 so as to be movable up and down, and a second sub-column 320 installed on one side of the first sub-column 310 so as to be movable up and down.

[0052] The first sub-column 310 is installed in a vertically movable manner on the front of the main column 200, and includes a pair of sub-frames 311 connected to the front of the pair of main frames 220 so as to be able to slide vertically, and a pair of movable frames 312 installed in parallel with the sub-frames 311 on the inner rear side of the pair of sub-frames 311. At this time, the pair of sub-frames 311 and the pair of movable frames 312 are integrally connected by cover frames 313 connected to the upper and lower ends, respectively.

[0053] The second sub-column 320 is installed in front of the first sub-column 310 so as to be movable up and down. The second sub-column 320 includes a pair of lift frames 321 respectively coupled to the inside of the pair of sub-frames 311 so as to be able to slide up and down, a lift plate 322 coupled to the front of the pair of lift frames 321 and disposed in front of the sub-frames 311, and an arm support bracket 323 coupled to the front of the lift plate 322. Although not shown in the drawings, the arm support bracket 323 can be extended and retracted in multiple stages, and an arm 3 having an X-ray source 4 at its end can be coupled thereto.

[0054] Hereinafter, the structure for moving the first sub-column 310 and the second sub-column 320 relative to the main column 200 will be described in detail with reference to FIGS.

[0055] 11, the first sub-column 310 is provided with a number of first rollers 314 on the outer side of a pair of movable frames 312, and the first rollers 314 are slidably coupled to first slide grooves 221 formed on the inner side of the main frame 220 of the main column 200. Therefore, when the first sub-column 310 moves up and down relative to the main column 200, the first rollers 314 of the movable frames 312 move along the first slide grooves 221 of the main frame 220.

[0056] 12, the second sub-column 320 is provided with a number of second rollers 324 on the outer side of a pair of lifting frames 321, and the second rollers 324 are slidably coupled to second slide grooves (not shown) formed on the inner side of the sub-frame 311 of the first sub-column 310. Therefore, when the second sub-column 320 moves up and down relative to the first sub-column 310, the second rollers 324 of the lifting frames 321 move along the second slide grooves of the sub-frame 311.

[0057] 13 is a partially enlarged view of the main column showing the weight compensation unit, but for convenience of explanation, the support frame is omitted. As shown in the figure, a first fixed pulley 410 is installed at the lower end of the main column 200. The first fixed pulley 410 can be rotatably supported by a support bracket 411 coupled to the upper side of the support plate 210.

[0058] In addition, a cam unit 440 is rotatably installed on the coupling frame 250 at the upper end of the support frame 240. The cam unit 440 may be rotatably supported by, for example, a rotation shaft penetrating the coupling frame 250 in the front-rear direction.

[0059] 14, the cam unit 440 includes a cam 450 formed to change the take-up radius, and at least one cam pulley 460 installed on one side of the cam 450 to rotate integrally with the cam 450. The drawing shows an example in which a pair of cam pulleys 460 are coupled, one on each side of the cam 450. The cam 450 and the cam pulley 460 may be formed integrally, or as another example, the cam 450 and the cam pulley 460 may be formed as separate members and then coupled to be rotatable integrally.

[0060] 5, the cam 450 has a curved surface 452 formed in a spiral shape within a predetermined angle section corresponding to the ascending / descending section of the sub-column 300 as a whole, and a straight surface 453 formed in the direction of the rotation axis at one end of the spiral curved surface 452. In addition, a second wire fixing part 454 having a groove 455 is formed on one side of the straight surface 453 so that the other end of the second wire 480 is fixed, and a first winding groove 456 for winding the second wire 480 is formed on the spiral curved surface 452 of the cam 450.

[0061] In addition, a second winding groove 461 is formed along the outer circumferential surface of the cam pulley 460, and a third wire fixing portion 462 is formed on one side of the cam pulley 460. One end of a third wire 490 is coupled to the third wire fixing portion 462, so that the third wire 490 is wound around the second winding groove 461 of the cam pulley 460 when the cam pulley 460 rotates.

[0062] 13, a pair of movable pulleys 420 are installed to be movable up and down and rotatable on the lower part of the cam unit 440. For example, the rotation shafts of the pair of movable pulleys 420 may be coupled to the lower end of an inverted U-shaped lift bracket 421.

[0063] At this time, one end of the second wire 480 is coupled to the upper end of the lifting bracket 421, and the other end of the second wire 480 passes through the first winding groove 456 of the cam 450 and is coupled to the second wire fixing part 454. Therefore, when the moving pulley 420 moves up and down, the second wire 480 is wound or unwound around the cam 450.

[0064] A first fixed pulley 410 is installed under the movable pulley 420. For example, the first fixed pulley 410 may be rotatably supported on an upper end of a “U” shaped support bracket 411 coupled to an upper surface of the support plate 210.

[0065] A first wire 430 is connected between a first fixed pulley 410 and a pair of movable pulleys 420, with one end of the first wire 430 being connected to one side of the main column 200 and the other end being connected to one side of the first sub-column 310 via the pair of movable pulleys 420 and the first fixed pulley 410.

[0066] To this end, a first fixture 222 is connected to one side of the lower part of the main frame 220 and protrudes rearward, a fixture bracket 315 is connected across the pair of moving frames 312, and a second fixture 316 is connected to the center of the fixture bracket 315 and protrudes rearward.

[0067] At this time, one end of the first wire 430 is connected to the first fixture 222, and the other end is connected to the second fixture 316 via a pair of movable pulleys 420 and a first fixed pulley 410, thereby connecting the main column 200 and the sub-column 300 by the first wire 430.

[0068] An elastic member 470 is installed on one side of the first fixed pulley 410. In this embodiment, a tension spring is shown as the elastic member 470, but this is only one example, and various types of elastic members 470 that provide elastic force, such as a gas spring or a torsion spring, can be used as needed.

[0069] The elastic member 470 is connected to the pair of cam pulleys 460 by a pair of third wires 490. For example, a third fixture 471 may be provided at the upper end of the elastic member 470, and one end of a pair of third wires 490 may be coupled to each end of the third fixture 471. The other end of the third wire 490 passes through the second winding groove 461 of the cam pulley 460 and is coupled to the third wire fixing portion 462, so that the third wire 490 is wound around the cam pulley 460 when the cam pulley 460 rotates.

[0070] Meanwhile, according to the first embodiment of the present invention, a linking mechanism for linking the elevation of the first sub-column 310 and the second sub-column 320 may be included, which will be described with reference to FIGS.

[0071] 7 and 9, a second fixed pulley 500 is rotatably installed on the upper end of the first sub-column 310. The second fixed pulley 500 is rotatably supported by a rotating shaft installed across the upper ends of the pair of moving frames 312, and a fourth wire 510 connects the main column 200 and the second sub-column 320 through the second fixed pulley 500.

[0072] At this time, a fourth fixture 223 is coupled to the lower part of the main column 200 across the pair of main frames 220, and one end of a fourth wire 510 is coupled to the fourth fixture 223. The other end of the fourth wire 510 is coupled to a fifth fixture 325 coupled to the lower end of the lift plate 322 of the second sub-column 320.

[0073] At this time, a pair of winding grooves may be formed in the second fixed pulley 500, spaced apart from each other at a predetermined interval, and a pair of fourth wires 510, one for each winding groove, may be coupled to the fourth fixture 223 of the main column 200 and the fifth fixture 325 of the second sub-column 320 via the second fixed pulley 500, respectively.

[0074] The lifting and lowering operation of the telescopic column 100 for an X-ray imaging apparatus according to the first embodiment of the present invention will be described in detail below.

[0075] When the first sub-column 310 and the second sub-column 320 are raised to their maximum relative to the main column 200, the user presses down on the second sub-column 320 to lower it, and the fourth wire 510, one end of which is connected to the lift plate 322 of the second sub-column 320, presses the second fixed pulley 500 to lower the first sub-column 310. When the first sub-column 310 is lowered, the first wire 430 causes the movable pulley 420 to lower toward the first fixed pulley 410, and the second wire 480 wound around the cam 450 is released, causing the cam 450 to rotate, and the cam pulley 460, which rotates together with the cam 450, winds up the third wire 490 to stretch the elastic member 470.

[0076] Conversely, when the user raises the second sub-column 320 upward in a state in which the first sub-column 310 and the second sub-column 320 are lowered to their maximum relative to the main column 200, the first sub-column 310 rises together with the second sub-column 320. At this time, the third wire 490 wound around the cam pulley 460 is loosened by the elastic restoring force of the elastic member 470, causing the cam pulley 460 to rotate. Then, the cam 450 rotates together with the cam pulley 460, winding up the second wire 480 to raise the movable pulley 420, thereby lifting the first sub-column 310.

[0077] At this time, the elastic force of the elastic member 470 compensates for the weight of the first and second sub-columns 310 and 320, allowing the user to easily move the first and second sub-columns 310 and 320 up and down with less force. Also, as described above, when the elastic force of the elastic member 470 changes, the torque of the cam 450 acts as a reaction torque against the torque of the cam pulley 460 to compensate for the elastic force of the elastic member 470 and the weight difference between the first and second sub-columns 310 and 320.

[0078] In the above-described embodiment, an interlocking telescopic column in which the second sub-column 320 moves up and down in conjunction with the movement of the first sub-column 310 has been described as an example. However, the weight compensation unit 400 including the cam 450 and the elastic member 470 according to the first embodiment of the present invention may also be applied to a non-interlocking telescopic column configured such that the first sub-column 310 moves up and down after the second sub-column 320 moves up and down, or the second sub-column 320 moves up and down after the first sub-column 310 moves up and down.

[0079] 15 to 26 are diagrams showing an expandable column for an X-ray imaging apparatus according to a second embodiment of the present invention. The expandable column for an X-ray imaging apparatus 1000 includes a main column 2000, a sub-column 3000 that is installed so as to be movable up and down relative to the main column 2000, and a weight compensation unit 4000 that compensates for the weight of the sub-column 3000.

[0080] The weight compensation unit 4000 includes a first fixed pulley 4100 and a movable pulley 4200 installed on the main column 2000, a first wire 4300 connecting the main column 2000 and the sub-column 3000, a cam 4410 whose winding radius changes depending on the elevation height of the sub-column 3000, and an elastic member 4500 that expands and contracts in response to the rotation of the cam 4410 to provide elastic force.

[0081] The main column 2000 can be installed vertically on the body (1, see FIG. 1) of the mobile X-ray imaging device, and a space is formed inside so that a weight compensation part 4000 including a number of pulleys and wires can be installed.

[0082] The sub-column 3000 is installed to be movable up and down on one side of the main column 2000. For example, a slide rail (not shown) may be formed on one side of the main column 2000, and the sub-column 3000 may be provided with a number of rollers to slide up and down along the slide rail.

[0083] In addition, an arm (3, see FIG. 1) having an X-ray source (4, see FIG. 1) at its end may be installed to be able to rise and fall on one side of the sub-column 3000. In this case, the arm may be formed to be able to be extended and retracted in multiple stages, and a weight compensation unit 4000 compensates for the weight of the sub-column 3000 including the X-ray source and the arm.

[0084] The weight compensation part 4000 may include a first fixed pulley 4100 rotatably installed on the upper end of the main column 2000, a movable pulley 4200 spaced apart from the lower part of the first fixed pulley 4100 and movable up and down, and a first wire 4300 connecting the main column 2000 and the sub-column 3000 via the first fixed pulley 4100 and the movable pulley 4200.

[0085] At this time, the number of the first fixed pulley 4100, the movable pulley 4200, and the first wire 4300 may be appropriately selected according to need. Also, as an example, one end of the first wire 4300 may be coupled to the upper end of the main column 2000, and the other end may be coupled to the sub-column 3000 after being wound around the movable pulley 4200 and the first fixed pulley 4100 several times.

[0086] A first wire 4300 connects the main column 2000 and the sub-column 3000 via a first fixed pulley 4100 and a moving pulley 4200 , so that when the sub-column 3000 moves up and down relative to the main column 2000 , the moving pulley 4200 moves up and down relative to the first fixed pulley 4100 .

[0087] At this time, the sub-column 3000 is manually raised and lowered by a user, and the weight compensation unit 4000 serves to enable the sub-column 3000 to be easily raised and lowered with little force despite the weight of the sub-column 3000.

[0088] For this reason, an elastic member 4500 that provides an elastic force to the sub-column 3000 is installed in the space of the main column 2000. The elastic member 4500 is installed to expand and contract in response to the elevation and lowering of the moving pulley 4200, and compensates for the weight of the sub-column 3000 by providing an elastic force to the sub-column 3000 together with the moving pulley 4200. For example, when the elastic force provided by the elastic member 4500 is balanced with the weight of the sub-column 3000, the user can easily raise and lower the sub-column 3000 with little force.

[0089] Meanwhile, the elastic force provided by the elastic member 4500 may change according to the elevation of the sub-column 3000. For example, when a tension spring is used as the elastic member 4500, the tension spring gradually expands as the sub-column 3000 is lowered, increasing the elastic force, and therefore the force required by the user to lower the sub-column also gradually increases.

[0090] The cam unit 4400 is provided so that the sub-column 3000 can be raised and lowered with a uniform force regardless of changes in the raised and lowered height of the sub-column 3000. The cam unit 4400 may be installed to rotate in conjunction with the raising and lowering of the movable pulley 4200. For example, one end of the second wire 4600 may be coupled to one side of the movable pulley 4200, and the other end may be wound around one side of the cam unit 4400. In this case, the second wire 4600 may be wound around one side of the cam unit 4400 via a third fixed pulley 4700 installed on one side of the elastic member 4500 as necessary.

[0091] In addition, the elastic member 4500 may be installed to expand and contract in conjunction with the rotation of the cam unit 4400. For example, one end of the third wire 4800 may be coupled to the elastic member 4500, and the other end may be coupled to the other side of the cam unit 4400.

[0092] More specifically, the cam unit 4400 includes a cam 4410 that is formed so that the winding radius of the second wire 4600 changes when the cam unit 4400 rotates, and a cam pulley 4430 that is installed on one side of the cam 4410 so as to rotate integrally with the cam 4410 and around which the third wire 4800 is wound.

[0093] In this case, when the sub-column 3000 rises, the tension spring is compressed, and the cam pulley 4430 rotates to loosen the third wire 4800. Then, the cam 4410 rotates together with the cam pulley 4430, and the second wire 4600 is wound around the cam 4410, and the second wire 4600 pulls the movable pulley 4200 downward.

[0094] Conversely, when the sub-column 3000 descends, the movable pulley 4200 rises, and the cam 4410 rotates to loosen the second wire 4600. Then, the cam pulley 4430 rotates together with the cam 4410, whereby the third wire 4800 is wound around the cam pulley 4430, and the tension spring is stretched by the third wire 4800.

[0095] At this time, a cam profile (profile0) is formed so that the winding radius of the second wire 4600 changes when the cam 4410 rotates (see FIG. 4). This is to allow the torque of the cam pulley 4430 according to the expansion and contraction of the elastic member 4500 and the torque of the cam 4410 according to the elevation and lowering of the movable pulley 4200 to act as a mutual reaction torque, so that the sub-column 3000 can be elevated and lowered with a uniform force regardless of the height of the sub-column 3000. For example, the spring force of the tension spring according to the rotation angle of the cam pulley 4430 and the torque of the cam pulley 4430 are calculated, and the radius of the cam 4410 is calculated from the torque of the cam 4410 to compensate for this, and a cam profile according to the rotation angle of the cam pulley 4430 can be derived.

[0096] The cam 4410 has a shape in which the radius gradually increases in one direction along the circumferential direction, and has an outer peripheral surface formed in a spiral shape within a predetermined angle section corresponding to the ascending and descending section of the sub-column 3000 as a whole, and a straight surface formed at the end of the spiral outer peripheral surface. In addition, a winding groove (4420, see FIG. 25) for winding the second wire 4600 is formed on the spiral outer peripheral surface of the cam 4410, and a fixing part for fixing the second wire 4600 is formed on one side of the straight surface.

[0097] Therefore, when the tension spring expands during the descent of the sub-column 3000 and the torque of the cam pulley 4430 increases, the winding radius of the second wire 4600 of the cam 4410 gradually increases, increasing the torque of the cam 4410. At this time, the torque of the cam 4410 acts as a reaction torque against the torque of the cam pulley 4430 to compensate for the elastic force of the tension spring and the weight difference of the sub-column 3000, and the user can raise and lower the sub-column 3000 with a uniform force regardless of the height of the sub-column 3000 or the extension length of the tension spring.

[0098] The telescopic column 1000 for an X-ray imaging device includes a main column 2000, a sub-column 3000 that is installed on one side of the main column 2000 so as to be movable up and down, and a weight compensation unit 4000 that is installed on the main column 2000 and compensates for the weight of the sub-column 3000, which can be understood in more detail with reference to Figures 17 to 21.

[0099] A support plate 2100 for supporting the main column 2000 is connected to the lower end of the main column 2000, and the support plate 2100 can be connected to the body of the mobile X-ray imaging device.

[0100] The main column 2000 includes a pair of main frames 2200 vertically installed at a predetermined distance apart in the width direction of the support plate 2100, an upper frame 2300 connected to the upper ends of the pair of main frames 2200, and a pair of support frames 2400 installed parallel to the main frames 2200 at a predetermined distance apart behind the main frames 2200.

[0101] The main frame 2200 serves to guide the sub-column 3000 in the ascending and descending direction, and a number of pulleys constituting the weight compensation unit 4000 are installed on the support frame 2400.

[0102] The sub-columns 3000 include a first sub-column 3100 installed on one side of the main column 2000 so as to be movable up and down, and a second sub-column 3200 installed on one side of the first sub-column 3100 so as to be movable up and down.

[0103] The first sub-column 3100 is installed in front of the main column 2000 so as to be movable up and down, and includes a pair of sub-frames 3110 each connected to the front of the pair of main frames 2200 so as to be slidable up and down, and a pair of movable frames 3120 installed in parallel with the sub-frames 3110 on the inner rear side of the pair of sub-frames 3110. At this time, the pair of sub-frames 3110 and the pair of movable frames 3120 are integrally connected by a cover frame 3130 connected to the upper ends and a lower frame 3140 connected to the lower ends.

[0104] The second sub-column 3200 is installed in a liftable manner on the front of the first sub-column 3100. The second sub-column 3200 includes a pair of lift frames 3210 respectively coupled to the inside of the pair of sub-frames 3110 so as to be able to slide vertically, a lift plate 3220 coupled to the front of the pair of lift frames 3210 and disposed in front of the sub-frames 3110, and an arm support bracket 3230 coupled to the front of the lift plate 3220. Although not shown in the drawings, the arm support bracket 3230 can be extended and retracted in multiple stages, and an arm having an X-ray source at its end can be coupled thereto. Hereinafter, the structure for moving the first sub-column 3100 and the second sub-column 3200 relative to the main column 2000 will be described in detail with reference to FIGS.

[0105] 22, the first sub-column 3100 is provided with a number of first rollers 3150 on the outer side of a pair of movable frames 3120, and the first rollers 3150 are slidably coupled to first slide grooves 2210 formed on the inner side of the main frame 2200 of the main column 2000. Therefore, when the first sub-column 3100 moves up and down relative to the main column 2000, the first rollers 3150 of the movable frames 3120 move along the first slide grooves 2210 of the main frame 2200.

[0106] 23, the second sub-column 3200 is provided with a number of second rollers 3240 on the outer side of a pair of lifting frames 3210, and the second rollers 3240 are slidably coupled to second slide grooves 3160 formed on the inner side of the sub-frame 3110 of the first sub-column 3100. Therefore, when the second sub-column 3200 is lifted or lowered relative to the first sub-column 3100, the second rollers 3240 of the lifting frames 3210 move along the second slide grooves 3160 of the sub-frames 3110.

[0107] 24, the first fixed pulley 4100 and the cam unit 4400 are rotatably installed on the upper end of the support frame 2400 of the main column 2000. At this time, the first fixed pulley 4100 and the cam unit 4400 are coupled on the same axis, but rotate independently of each other. That is, the cam unit 4400 is rotatably coupled to the rotation shaft of the first fixed pulley 4100 by, for example, a bearing (not shown).

[0108] 25, the cam unit 4400 includes a cam 4410 formed to change the take-up radius, and at least one cam pulley 4430 installed on one side of the cam 4410 to rotate integrally with the cam 4410. The cam 4410 and the cam pulley 4430 may be integrally formed, or as another example, the cam 4410 and the cam pulley 4430 may be formed as separate members and then coupled to be integrally rotatable.

[0109] 24 again, a plurality of first guide pulleys 4900 are rotatably installed on a rotary shaft below the first fixed pulley 4100 and the cam unit 4400. The first guide pulleys 4900 serve to guide the winding direction of the wire wound around the cam 4410 and the wire wound around the cam pulley 4430.

[0110] A movable pulley 4200 is installed below the first guide pulley 4900 so as to be movable up and down, and a “U” shaped wire fixing bracket 4210 is coupled to the rotation shaft of the movable pulley 4200 .

[0111] A third fixed pulley 4700 is installed under the movable pulley 4200. For example, the third fixed pulley 4700 may be rotatably supported by a first support bracket 4710 coupled to an upper surface of the support frame 2400.

[0112] A second guide pulley 5000 may be rotatably installed between the movable pulley 4200 and the third fixed pulley 4700 by a second support bracket 5100. The second guide pulley 5000 has one end connected to the wire fixing bracket 4210 and serves to guide the moving direction of the second wire 4600 extending upward through the third fixed pulley 4700.

[0113] A first wire 4300 connects the main column 2000 and the first sub-column 3100 via a first fixed pulley 4100 and a movable pulley 4200. Referring to Fig. 26 together with Fig. 24, one end of the first wire 4300 is coupled to the upper frame 2300 of the main column 2000 by a fixture, and the other end is wound around the movable pulley 4200 and the first fixed pulley 4100 several times and then coupled to the movable frame 3120 of the first sub-column 3100 by a fixture. Therefore, when the first sub-column 3100 is raised or lowered, the movable pulley 4200 rises or lowers relative to the first fixed pulley 4100.

[0114] 24 again, a second wire 4600 is connected between the movable pulley 4200 and the cam unit 4400 so that the cam unit 4400 rotates in conjunction with the elevation and lowering of the movable pulley 4200. In detail, one end of the second wire 4600 is coupled to the wire fixing bracket 4210, and the other end is coupled to one side of the winding groove 4420 of the cam 4410 via a third fixed pulley 4700, so that the second wire 4600 is wound or unwound around the cam 4410 when the movable pulley 4200 is elevated or lowered.

[0115] In addition, the cam pulley 4430 and the elastic member 4500 are connected by a third wire 4800, one end of which is connected to the upper end of the elastic member 4500 and the other end of which extends upward and is wound around the cam pulley 4430. Therefore, when the cam pulley 4430 rotates together with the cam 4410 when the cam 4410 rotates, the elastic member 4500 may expand and contract in conjunction with the rotation of the cam 4410, and the cam 4410 may rotate together with the cam pulley 4430 in conjunction with the expansion and contraction of the elastic member 4500.

[0116] In addition, according to the second embodiment of the present invention, a linkage mechanism may be included that allows the second sub-column 3200 to be raised and lowered in conjunction with the raising and lowering of the first sub-column 3100, which will be described with reference to Figures 20 and 21.

[0117] 20 and 21, a fourth fixed pulley 5200 is rotatably installed on the upper end of the first sub-column 3100, and a fourth wire 5300 passes through the fourth fixed pulley 5200 of the first sub-column 3100 to connect the main column 2000 and the second sub-column 3200.

[0118] Here, the fourth fixed pulley 5200 determines the stroke ratio of the second sub-column 3200 to the first sub-column 3100 when the second sub-column 3200 ascends and descends in conjunction with the ascending and descending of the first sub-column 3100. To this end, for example, the fourth fixed pulley 5200 may be configured as a two-stage radius pulley having two different radii.

[0119] At this time, one end of the fourth wire 5300 is connected to a fixed bracket 5400 installed on the upper side of the support plate 2100 at the bottom of the main column 2000, and the other end is connected to the lifting frame 3210 of the second sub-column 3200 via the fourth fixed pulley 5200 of the first sub-column 3100 (see FIG. 23).

[0120] The lifting and lowering operation of the telescopic column 1000 for an X-ray imaging apparatus according to the second embodiment of the present invention will be described in detail below.

[0121] When the first sub-column 3100 and the second sub-column 3200 are raised to their maximum relative to the main column 2000, and the user pushes down on the second sub-column 3200 to lower it, the fourth wire 5300, one end of which is connected to the lifting frame 3210 of the second sub-column 3200, pushes the fourth fixed pulley 5200, causing the first sub-column 3100 to lower.

[0122] When the first sub-column 3100 descends, the first wire 4300 causes the movable pulley 4200 to rise toward the first fixed pulley 4100, and the second wire 4600 wound around the cam 4410 is released, causing the cam 4410 to rotate, and the cam pulley 4430, which rotates together with the cam 4410, winds up the third wire 4800, stretching the elastic member 4500.

[0123] Conversely, when the user raises the second sub-column 3200 upward in a state in which the first sub-column 3100 and the second sub-column 3200 are lowered to their maximum relative to the main column 2000, the second sub-column 3200 rises together with the first sub-column 3100, and the third wire 4800 wound around the cam pulley 4430 is loosened by the elastic force of the elastic member, causing the cam pulley 4430 to rotate. At this time, the cam 4410 rotates together with the cam pulley 4430, winding up the second wire 4600 and lowering the movable pulley 4200.

[0124] At this time, the stroke ratio of the second sub-column 3200, which rises and falls in conjunction with the rise and fall of the first sub-column 3100, is determined by the fourth fixed pulley 5200, which is composed of a two-stage radius pulley. The elastic force of the elastic member 4500 compensates for the weight of the first and second sub-columns 3100 and 3200, allowing the user to easily lower the first and second sub-columns 3100 and 3200 with little force.

[0125] Also, as described above, when the elastic force of the elastic member 4500 changes, the torque of the cam 4410 acts as a reaction torque against the torque of the cam pulley 4430 to compensate for the elastic force of the elastic member 4500 and the weight difference between the first and second sub-columns 3100 and 3200.

[0126] Although the embodiments of the present invention have been described above, it will be understood that the present invention can be embodied in various modified forms without departing from the scope of the claims, by anyone having ordinary skill in the art to which the present invention pertains. [Industrial Applicability]

[0127] According to the telescopic column for an X-ray imaging device of the present invention, the length of the column can be extended or shortened manually, quickly and easily without a separate driving source or weight.

Claims

1. Main column: a sub-column installed on one side of the main column in a vertically movable manner; a weight compensation unit provided on the other side of the main column to compensate for the weight of the sub-column; the weight compensation unit includes a cam formed so that a winding radius of the wire changes according to a lifting height of the sub-column; and an elastic member that expands and contracts according to a rotation of the cam to provide an elastic force to compensate for the weight of the sub-column, The cam has a shape in which the radius gradually increases in one direction along the circumferential direction within a predetermined angle section, The weight compensation unit is a first fixed pulley installed on the main column; a movable pulley installed so as to be movable up and down with respect to the first fixed pulley; a first wire having one end connected to the main column and the other end connected to the sub-column via the movable pulley and the first fixed pulley; a cam unit installed to rotate in conjunction with the elevation and lowering of the movable pulley; and an elastic member that expands and contracts in conjunction with the rotation of the cam unit to provide an elastic force to the sub-column.

2. 2. The telescopic column for an X-ray imaging apparatus according to claim 1, wherein the sub-columns include a first sub-column installed on one side of the main column so as to be movable up and down, and a second sub-column installed on one side of the first sub-column so as to be movable up and down.

3. a linking mechanism for linking the lifting and lowering of the second sub-column with the lifting and lowering of the first sub-column, 3. The telescopic column for an X-ray imaging apparatus according to claim 2, wherein the interlocking mechanism includes a second fixed pulley installed at an upper end of the first sub-column, and a fourth wire having one end connected to the main column and the other end connected to the second sub-column via the second fixed pulley.

4. Main column: a sub-column installed on one side of the main column in a vertically movable manner; a weight compensation unit provided on the other side of the main column to compensate for the weight of the sub-column; The weight compensation unit is a first fixed pulley installed on the main column; a movable pulley installed so as to be movable up and down relative to the first fixed pulley; a first wire having one end connected to the main column and the other end connected to the sub-column via the movable pulley and the first fixed pulley; a cam unit installed to rotate in conjunction with the elevation and lowering of the movable pulley; an elastic member that expands and contracts in conjunction with the rotation of the cam unit to provide an elastic force to the sub-column; a second wire having one end connected to one side of the movable pulley and the other end wound around one side of the cam unit; and a third wire having one end connected to the elastic member and the other end wound around the other side of the cam unit.

5. 5. The telescopic column for an X-ray imaging apparatus according to claim 4, wherein the cam unit includes a cam formed so that a winding radius of the second wire changes when the cam unit rotates, and a cam pulley installed on one side of the cam to rotate integrally with the cam and around which the third wire is wound.

6. 6. The telescopic column for an X-ray imaging apparatus according to claim 5, wherein a torque of the cam corresponding to the vertical movement of the moving pulley acts as a reaction torque against a torque of the cam pulley corresponding to the expansion and contraction of the elastic member.

7. 5. The telescopic column for an X-ray imaging device according to claim 4, wherein the weight compensation part includes a third fixed pulley installed on one side of the elastic member, and the second wire passes through the third fixed pulley and is wound around one side of the cam unit.

8. the sub-columns include a first sub-column installed on one side of the main column so as to be movable up and down, and a second sub-column installed on one side of the first sub-column so as to be movable up and down, a linking mechanism for linking the lifting and lowering of the second sub-column with the lifting and lowering of the first sub-column, 8. The telescopic column of claim 7, wherein the linkage mechanism includes a fourth fixed pulley installed at an upper end of the first sub-column, and a fourth wire having one end coupled to one side of the main column and the other end coupled to one side of the second sub-column via the fourth fixed pulley.

9. Main column: a sub-column installed on one side of the main column in a vertically movable manner; a weight compensation unit provided on the other side of the main column to compensate for the weight of the sub-column; the sub-columns include a first sub-column installed on one side of the main column so as to be movable up and down, and a second sub-column installed on one side of the first sub-column so as to be movable up and down, a first wire having one end coupled to the main column and the other end coupled to the sub-column via the movable pulley and the first fixed pulley; a cam installed to rotate in conjunction with the elevation of the movable pulley; a pair of cam pulleys installed on both sides of the cam to rotate integrally with the cam; a second wire having one end coupled to one side of the movable pulley and the other end wound around the cam; an elastic member that expands and contracts in conjunction with the rotation of the cam pulley to provide an elastic force to the sub-column; a third wire having one end wound around the cam pulley and the other end coupled to the elastic member;

Images