Elevating mechanism for flat-panel display monitor and pneumatic cylinder used for elevating mechanism

[0001] 1. Field of the Invention

[0002] The present invention generally relates to elevating mechanisms, and particularly, to an elevating mechanism for a flat-panel display monitor and a pneumatic cylinder for adjusting the height of the elevating mechanism.

[0003] 2. Discussion of the Related Art

[0004] Display devices of the computers come in a variety of sizes, shapes, and weights. Flat-panel display monitors, such as liquid crystal display (LCD) monitors, are widely used because of their thin bodies and light weight.

[0005] LCD monitors can also be versatile. Generally, the height of the flat-panel display monitor can be adjusted via an elevating mechanism.

[0006] Referring to FIG. 7, a typical elevating mechanism 100 includes a support member 10, a mounting bracket 20, and a coil spring 30. The support member 10 includes an elongated main portion (not labeled), and two side portions (not labeled) extending from opposite sides of the elongated main portion. The main portion and the side portions cooperatively define a receiving groove 11 for mounting the mounting bracket 20. Two guide rails 12 are formed on opposite inner surfaces of the side portions. The support member 10 further defines two fixing holes 13 adjacent to top ends of the side portions.

[0007] The mounting bracket 20 includes a middle portion (not labeled), two sliding portions (not labeled) extending from opposite sides of the middle portion, and a connecting portion 21 connected to an end of the middle portion. The middle portion defines two threaded holes 22 in another end of the middle portion opposite to the connecting portion 21. The two sliding portions are configured to engage in the guide rails 12 of the support member 10 so that the mounting bracket 20 is slidable in the receiving groove 11.

[0008] The coil spring 30 includes a first end coiled to a shaft 31 and a second end opposite to the first end defining two through holes 32. The shaft 31 defines two fixing holes 311 in opposite ends of the shaft 31. The shaft 31 is fixed to the support member 10 by using screws 33 to pass through the fixing holes 311 and screwed into the two corresponding fixing holes 13 of the support member 10. The second end of the coil spring 30 is fixed to the mounting bracket 20 by using screws 36 to pass through the through holes 32 and screwed into the corresponding threaded holes 22.

[0009] The connecting portion 21 of the mounting bracket 20 supports a flat-panel display (not shown). To lower the height of the flat-panel display, an external force is applied to the flat-panel display causing the mounting bracket 20 to slide downwards relative to the support member 10. When the mounting bracket 20 slides to a desired position, the external force is released. The mounting bracket 20 with the flat-panel display remains in the desired position by an elastic force from the coil spring 30 and a friction force created between the mounting bracket 20 and the support member 10. To raise the height of the flat-panel display, another external force is applied to the flat-panel display for lifting the mounting bracket 20 to slide upwards relative to the support member 10 to another desired position.

[0010] However, the support member 10 and the mounting bracket 20 are generally heavy. In addition, the conventional elevating mechanism 100 has a relatively short usage life because the coil spring 30 damages easily when it is frequently operated. Furthermore, a user needs to exert great force to the flat display to overcome the friction force created between the mounting bracket 20 and the support member 10.

[0011] Therefore, a new elevating mechanism for a flat-panel display monitor is desired to overcome the above-described shortcomings.

[0012] An elevating mechanism used for a flat-panel display monitor includes a support structure, a sliding structure, and a pneumatic cylinder. The support structure includes a pair of guide rails. The sliding structure is mounted to the support structure and is capable of sliding along the guide rails.

[0013] The pneumatic cylinder includes a cylinder body, a piston shaft, and a first piston. The cylinder body is connected to the support structure. The piston shaft includes a first end received in the cylinder body, and a second end opposite to the first end connected to the sliding structure. The first piston is positioned in the cylinder body and partitions the cylinder body into two chambers. The two chambers are filled with gas. The first piston is fixed to the first end of the piston shaft and defines a through hole for communicating the two chambers.

[0014] Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0023] Reference will now be made to the drawings to describe embodiments of the present elevating mechanism in detail.

[0024] Referring to FIG. 1, a flat-panel display monitor 40 includes a flat-panel display 50, an elevating mechanism 60, and a base member 70. The elevating mechanism 60 adjustably connects the flat-panel display 50 and the base member 70.

[0025] Referring to FIGS. 2 and 3, the elevating mechanism 60 includes a support structure 61, a sliding structure 63, a first linking module 64, a pneumatic cylinder 65, a second linking module 66 and a plurality of fixing members (not shown).

[0026] Referring also to FIG. 4, the support structure 61 includes a mounting bracket 610, two guide rails 611, two friction members 612, and a support bracket 613. The mounting bracket 610 includes a main portion 614 and two side portions 615 perpendicularly extending from opposite sides of the main portion 614. Each of the side portions 615 defines a plurality of fixing holes 616 adjacent to a center of the side portion 615, a plurality of positioning holes 6151 adjacent to an end of the side portion 615, and a rectangular hole 617 between the fixing holes 616 and the positioning holes 6151. Each of the side portions 615 includes a rectangular block piece 618 extending inwards from an edge of the rectangular hole 617.

[0027] Each guide rail 611 includes a base wall 619 and two side walls 620 perpendicularly extending from opposite sides of the base wall 619. The base wall 619 defines a plurality of through holes 621 corresponding to the fixing holes 616, such that the guide rails 611 can be fixed to the inner sides of the corresponding side portions 615 by fixing members, such as screws.

[0028] Each friction member 612 includes a base portion 623 and two side portions 624 perpendicularly extending from opposite sides of the base portion 623. Each friction member 612 includes a plurality of ball-shaped protrusions (not labeled) positioned at opposite surfaces of each side portion 624.

[0029] The support bracket 613 defines a rectangular mounting groove 625 in a top portion. The support bracket 613 includes a pair of parallel first side walls 626 and a pair of parallel second side walls 628 surrounded the mounting groove 625. Each first side wall 626 is longer than each second side wall 628 and defines a through hole 627 in a middle. Each second side wall 628 defines a plurality of fixing holes 629 corresponding to the positioning holes 6151 so that the mounting bracket 610 can be connected to the support bracket 613 by fixing members, such as screws.

[0030] The sliding structure 63 includes a sliding bracket 630 and two slide rails 631. The sliding bracket 630 includes a rectangular base 632, two side walls 633 perpendicularly extending from opposite sides of the base 632, and a top cover 634 perpendicularly extending from a top side of the base 632. The top cover 634 is also perpendicularly connected to the side walls 633. Each side wall 633 defines a plurality of fixing holes 635. The sliding bracket 630 further includes a plurality of connecting pieces 636 extending outwards from the base 632 configured for connecting the flat-panel display 50 to the sliding structure 63. Each of the slide rails 631 includes a rectangular base wall 637 and two side walls 638 perpendicularly extending from opposite sides of base wall 637. The base wall 637 defines a plurality of through holes 639 corresponding to the fixing holes 635 so that the slide rails 631 can be fixed to the corresponding side walls 633.

[0031] The first linking module 64 includes a shaft 641, two sleeves 642, and a connecting member 643. The shaft 641 is cylindrical. The sleeves 642 are hollow cylinders and can be sleeved on the shaft 641. The connecting member 643 defines a shaft hole 644 extending through a side portion for the shaft 641. The connecting member 643 also defines a threaded hole (not labeled) in a bottom portion. A central axis of the threaded hole is substantially perpendicular to a central axis of the shaft hole 644.

[0032] Referring also to FIG. 6, the pneumatic cylinder 65 includes a piston shaft 651, a cylinder body 652, a connecting portion 653 (see FIG. 2), a first piston 654, a second piston 655, and a ring seal 656. The first piston 654 and the second piston 655 are positioned in the cylinder body 652 and partition the cylinder body 652 into three chambers A, B, and C. The chambers A and B are filled with gas to a predetermined pressure, and the chamber C is filled with oil for preventing the gas from escaping out of the chambers A and B. The first piston 654 defines a through hole 657 extending through so the chamber A is in fluid communication with the chamber B. The piston shaft 651 is partially received in the cylinder body 652 from an end of the cylinder body 652 adjacent to the chamber C. The connecting portion 653 is a threaded portion extending from an end of the cylinder body 652 adjacent to the chamber A. The first piston 654 is fixed to an end of the piston shaft 651, and the second piston 655 is movably sleeved on the piston shaft 651. The first piston 654 includes a spherical portion 658 formed at an end surface, extending towards the first chamber A. The spherical portion 658 is configured to prevent the whole end surface of the first piston 654 from abutting an inner bottom surface of the cylinder body so that the volume of the gas in the chamber A can never be zero. The ring seal 656 is sleeved on the piston shaft 651 and abuts an end of the cylinder body 652 adjacent to the chamber C, thereby preventing the oil from leaking out of the chamber C.

[0033] The second linking module 66 includes a connecting member 662 and a pin 663. The connecting member 662 is similar in principle to the connecting member 643. The connecting member 662 defines a threaded hole 664 in a top portion and a pin hole 665 extending through a side portion for the pin 663. A central axis of the threaded hole 664 is substantially perpendicular to a central axis of the pin hole 665. The threaded hole 664 is configured for engaging with the connecting portion 653 of the pneumatic cylinder 65.

[0034] Referring also to FIG. 5, the elevating mechanism 60 is assembled by fixing the guide rails 611 to the corresponding inner sides of the side portions 615 with fasteners, such as screws. An end of each guide rail 611 should abut the block piece 618. The friction members 612 are slidably received in the corresponding guide rails 611, and the base portion 623 of each friction member 612 abuts the corresponding base wall 619. The slide rails 631 are fixed to the corresponding side walls 633 of the sliding bracket 630. The shaft 641 is passed through the shaft hole 644 of the connecting member 643, and the two sleeves 642 are sleeved on the shaft 641 adjacent to opposite sides of the connecting member 643. Opposite ends of the shaft 641 are passed through the fixing holes 635 and latched in the corresponding through holes 639. The slide rails 631 are latched to the corresponding friction members 612, and the base wall 637 of each slide rail 631 is positioned adjacent to the base portion 623 of the corresponding friction member 612. Thus each slide rail 631, together with the corresponding friction member 612, is capable of sliding in the corresponding guide rail 611. An end of the piston shaft 651 is screwed into the threaded hole of the connecting member 643 to connect the sliding structure 63 to the pneumatic cylinder 65. The connecting portion 653 of the pneumatic cylinder 65 is screwed into the threaded hole 664 of the connecting member 662. The connecting member 662 is received in the mounting groove 625 of the support bracket 613. The pin 663 is passed through the through holes 627 and the pin hole, to fixedly connect an end of the pneumatic cylinder 65 to the support bracket 613. The flat-panel display 50 is fixed to the connecting pieces 636 so that the flat-panel display 50 moves with the sliding structure 63 relative to the support structure 61.

[0035] The principle and work process of the pneumatic cylinder 65 will be illustrated in detail.

[0036] In the following description, P₀ represents the pressure of the gas in the chambers A and B, S₀ represents an area of a cross-section of the piston shaft 651, S₁ represents an area of a cross-section of the first piston 654, S₂ represents an area of an surface of the first piston 654 in the chamber B. The pressure P₀ is actually much larger than the atmospheric pressure, thus the effect of the atmospheric pressure on the pneumatic cylinder 65 does not need to be considered. According to the theory of physics,
F₁=P₀S₁,
F₂=P₀S₂,

[0037] wherein F₁ represents a pressure force on the first piston 654 created by the gas in the chamber A and F₂ represents a pressure force on the first piston 654 created by the gas in the chamber B.

[0038] The relations of the area S₀, the area S₁, and the area S₂ are as follows:
S₂=S₁−S₀, thus
F₂=P₀S₂=P₀(S₁−S₀)

[0039] If ΔF represents a difference value between the pressures of the two sides of the first piston 654, thus,

[0040] $\begin{array}{c}\Delta F=F_1-F_2\\ =P_0{S}_1-P_0{S}_2\\ =P_0\left(S_1-S_2\right)\\ =P_0\left[S_1-\left(S_1-S_0\right)\right]\\ =P_0{S}_0\end{array}$

[0041] The above formulas shows that, if the chambers A, B is filled with gas having a predetermined pressure P₀, a pressure force ΔF will be created on the first piston 654. The pressure force ΔF is determined by the pressure P₀ of the gas in the chambers A and B and the area S₀. Thus, the pressure force ΔF can be adjusted by adjusting the pressure P₀ and the area S₀.

[0042] The elevating mechanism 60 utilizes the principle and work process of the pneumatic cylinder. The chamber A communicates with the chamber B via the through hole 657 of the first piston 654, so the pressure of the gas in the chambers A and B are equal at a predetermined pressure, P₀. If the position of the second piston 655 does not change, the total volume and pressure of the gas in the chambers A and B will remain the same, and the pressure force ΔF is changeless. To lower the flat-panel display 50 relative to the base member 70, an external force is applied on the flat-panel display monitor pressing the sliding structure 63 to slide downwards relative to the mounting bracket 610. Because the piston shaft 651 is connected to the sliding structure 63, the piston shaft 651 moves with the first piston 654, and the volume of the chamber A is accordingly decreased because of the motion of the first piston 654. When the sliding structure 63 slides downwards to a desired position, the external force is released, the pressure force ΔF and a fiction force created between the guide rails 611 and the slide rails 631 counter-balance the weight of the sliding structure 63 and the flat-panel display 50. Thus, the sliding structure 63 with the flat-panel display 50 can be retained at the predetermined position by the pressure force ΔF and the fiction force. Similarly, to raise the flat-panel display 50 relative the base member 70, another external force is applied on the flat-panel display monitor 50 for lifting the sliding structure 63 to slide upwards relative to the mounting bracket 610 to another desired position.

[0043] The pressure P₀ can be changed by changing the position of the second piston 655 to increase or decrease the total volume of the gas in the chambers A, B, thereby adjusting the pressure force ΔF. Therefore, the elevating mechanism 60 can be used for flat-panel display monitors having different weights by adjusting the pressure force ΔF. Alternatively, the second piston 655 can be omitted, and the pressure P₀ can be adjusted by further injecting gas into the chambers A, B.

[0044] The pneumatic cylinder 65 of the elevating mechanism 60 has a relatively small size and weight, thereby decreasing the overall size and weight of the elevating mechanism 60. In addition, the pneumatic cylinder 65 of the elevating mechanism 60 generally has a longer usage life than a coil spring. Furthermore, when the elevating mechanism 60 is used for flat-panel display monitors having different weights, the pressure force ΔF created by the pneumatic cylinder 65 can be conveniently adjusted by the second piston 655.

[0045] It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.