Lifting mechanism with support function

A lifting mechanism with support function includes pivot arm component composed of a first pivot arm and a second pivot arm parallel to each other. The first and second pivot arms each have two ends thereof pivotally connected to a fixation joint and an active joint respectively, and the pivotally connected points connecting the first link, the second link, the fixation joint and the active joint jointly define a parallelogram. One end of an adjustable damper pivotally connects to the pivot arm component, and the other end thereof pivotally connects to the fixation joint or the active joint via an adjustment component, so the adjustable damper can be controlled to extend/retract or be locked; the adjustment component includes a first pivot seat capable of relatively moving to change the support angle of the adjustable damper to adjust the damping support force provided from the adjustable damper.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a lifting mechanism with support function, in particular to a lifting mechanism which can be controlled to vertically extend/retract and revolve, and can be controlled to adjust its support.

2. Description of Related Art

An office chair with a gas cylinder is an example for devices that have a simple lifting mechanism that allows easy altitudinal adjustment. In a conventional office chair, a seat is connected to a caster-equipped base through a pneumatic device. The pneumatic device is operated by a switch to place the seat at different altitudes that meets various needs in use. However, such a structure can only realize altitudinal adjustment, and does not support displacement in other directions (such as forward/backward or leftward/right displacement), making its use limited.

There is also a mechanism having a post (or a plurality of links) connected to a loading platform (for receiving a keyboard and a monitor) through at least one pneumatic element (such as a gas cylinder). It is such designed that the support force forms the pneumatic element is slightly greater than the overall weight of the loading platform (plus the keyboard and the monitor), so that after the loading platform (plus the keyboard and the monitor) is adjusted to a desired position, it is held at that position and a balanced posture of the whole mechanism is formed. While this structure allows altitudinal and positional adjustment depending on the characteristics of the used post (or the plural links), the balance between the loading platform and the pneumatic element tends to be broken by external force (such as that from a user's palms pressing loading platform when operating a keyboard placed on the) in practical use. When the user operates the mechanism, the loading platform gradually descends; for the reason, the user should use his arm and hand to lift the loading platform, which will result in potential mental pressure; besides, the user may suffer from tendonitis if using the mechanism for a long time, which making it inconvenient to use.

In view of the shortcomings of the known lifting devices, the inventor of the present invention has made improvements thereto and creates the present invention.

SUMMARY OF THE INVENTION

The present invention is to use a pivot arm component to provide a linkage supporting between a preset loading component and a loading platform set, and a damping positioning mechanism is located between the linkage and the loading component, so that the damping positioning mechanism that can be controlled to extend or retract, and can automatically position the linked structure after operation, the loading platform set can be well positioned at its post-adjustment position.

The present invention is to make the damping positioning mechanism and the pivot arm component arranged between different loading components and loading platform sets as needed, so as to improve the application of the device and add value to the final products using the same.

The present invention can form a parallelogram by the linkage of the pivot arm component, the fixation joint of the loading component and the active joint of the loading platform set, so that the loading platform set can be freely moved upward/downward, forward/backward, or rightward/leftward in a certain angular area, while remaining horizontal, thereby providing convenient use.

The active joint and the fixation joint of the present invention can further work with a revolver so that the loading platform set is allowed to perform rotation in both directions in addition to relative movements, thereby improving its convenience in use.

Besides, the present invention is further to provide an adjustment component to the front end of the adjustment damper, so that the front end of the adjustment damper can be located at the first pivot seat; the support angle of the adjustment damper can be changed by adjusting the position of the first pivot seat so as to further change the adjustment damper's damping support forse provided for the loading platform set; in this way, the user can adjust the adjustment damper to the proper angle according to the loading weight so as to achieve balance and decrease the burden of the descending/ascending operation, which can increase the convenience.

To achieve the foregoing objectives and effects, the present invention implements the following technical scheme: a fixation joint; an active joint, connecting to a loading platform set; a pivot arm component installed between the fixation joint and the active joint, including a first pivot arm and a second pivot arm, wherein one end of the first pivot arm and one end of the second pivot arm are pivotally connected to the fixation joint, and the other end of the first pivot arm and the other end of the second pivot arm are pivotally connected to the active joint, the relation position of the first pivot arm, the second pivot arm, the pivot shaft of the fixation joint and the pivot shaft of the active joint substantially form a parallelogram, whereby the first pivot arm and the second pivot arm are able to pivot within a certain range, and the active joint descends or ascends relative to the fixation joint; a damping positioning mechanism, including an adjustable damper and a switch, wherein one end of the adjustable damper is installed on the pivot arm component, and the other end of the adjustable damper connects to the fixation joint or the active joint via an adjustment component; and the adjustable damper is connected to the switch via a control cord, and able to be controlled by the switch to be the adjustable status or the locked status; the adjustable damper is able to extend or retract and provides some damping support forse during the adjustable status, so the active joint is able to pivot relative to the fixation joint via the pivot arm component; the adjustable damper is able to fix the angle between the pivot arm component, and the active joint or fixation joint during the locked status for positioning; further, the adjustment component includes a first pivot seat capable of relatively moving, and the end of the adjustable damper pivotally connects to the first pivot seat, and the support angle of the adjustable damper is able to be changed by adjusting the position of the first pivot seat so as to adjust the damping support forse provided from the adjustable damper to support the loading platform set.

Thereby, the damper can provide proper damping support forse, and can sue the adjustment component to achieve balance in accordance with the total load born by the loading platform set. In addition, the switch controls the damper to extend or retract or get locked from extending or retracting. A user can easily move the loading platform set by pressing the switch an applying a minor force to reposition the loading platform set to a desired position. During the movement, the user does not need to hold and bear the loading platform set, and when moved to the desired position, the loading platform set can be easily positioned by the user's releasing the switch which locks the damper. The loading platform set is thus secured from being moved under external force, thereby significantly improving convenience in use.

In the configuration discussed above, the end of the adjustable damper connects to the first pivot arm or the second pivot arm via a second pivot seat.

In the configuration discussed above, the adjustment component further includes a lead screw, and the first pivot seat is mounted on the lead screw; when the lead screw revolves, the first pivot seat is able to move toward to lead screw.

In the configuration discussed above, the adjustment component further connects to an indicator mechanism for displaying the measurement of the damping support forse provided for the loading platform set.

In the configuration discussed above, the indicator mechanism includes a gear set connecting to the lead screw; the gear set is able to revolve by being linked to the lead screw, and display the measurement of the damping support forse provided for the loading platform set via an opening externally exposed to outside.

In the configuration discussed above, the indicator mechanism includes an indicator connecting to the first pivot seat, and the indicator is able to move with the first pivot seat, and display the measurement of the damping support forse provided for the loading platform set via a front end protruding outward.

In the configuration discussed above, the first pivot arm and the second pivot arm pivotally connect to an inner position and an outer position respectively via a plurality of shaft sleeves; the first pivot arm and the second pivot arm have lateral walls capable of overlapping with each other, whereby the lateral walls are able to partially overlap with each other when the first pivot arm and the second pivot arm are in operation.

In the configuration discussed above, wherein the active joint further includes a connection board and a locking sheet, and the first pivot arm and the second pivot arm are pivotally installed between the connection board and the locking sheet.

In the configuration discussed above, the locking sheet is fixed on the connection board via three points substantially form a triangle; the first pivot arm and the second pivot arm respectively pivotally connect to one of the three points.

In the configuration discussed above, the fixation joint is fixed at a base, a clamping base or a revolver.

In the configuration discussed above, the active joint connects to a platform or a pivot holder.

The invention as well as a preferred mode of use, further objectives and advantages thereof will be best understood by reference to the following detailed description of illustrative embodiments when read in conjunction with the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is majorly based on the pivot mechanism formed by two parallel pivot arms; the present invention can have many modes according to actual applications, but all of which are based on the same basic structure and operation principle. As shown inFIG. 1AandFIG. 1B, the pivot arm component P3is pivotally installed between a fixation joint P11and an active joint P211. The fixation joint P11is usually the fixation end for forming a fixation support point; on the contrary, the active joint P211is usually the active end for connecting to a platform capable of ascending/descending. Besides, the pivot arm component P3has a first pivot arm P31and a second pivot arm P32parallel to each other, and the pivot shaft connection line between both ends of which, and the fixation joint P11and the active joint P211can just from a parallelogram, such that when the first and second pivot arms P31, P32revolve, the active joint P211can keep a constant angle displacement, and the platform connected to which can also horizontally ascend or descend. As shown inFIG. 1A, the pivotal connection position of the first and second pivot arms P31, P32is slope (the included angle of the pivot shaft connection line of them and the horizontal plane is about) 45°, so they are suitable for 0˜90° ascending/descending operations. As shown inFIG. 1B, the pivotal connection position of the first and second pivot arms P31, P32is vertical, so they are suitable for −45˜45° ascending/descending operations. In other words, many application modes can be provided according to the relation position of the first and second pivot arms P31, P32.FIG. 1AandFIG. 1Bjust show the preferred application modes of the present invention, which have the same structure of the pivot arm component P3and the pivot operation principle.

Referring toFIGS. 2 and 3, according to the first embodiment of the lifting mechanism with support function of the present invention, the disclosed mechanism comprises: a loading component1, a loading platform set2, a pivot arm component3, and a damping positioning mechanism4. Therein, the loading component1is locally provided with a fixation joint11, and the fixation joint11contains therein a first pivot seat12.

In the present embodiment, the loading component1is a flat base, which can be stably placed on a predetermined plane, and the joint11and the first pivot seat120are installed on the base.

The loading platform set2is composed of a first loading platform21and a second loading platform22. The first and second loading platform21,22are connected to each other by means of an extension support23, so that the first and second loading platforms21,22are mutually parallel and have an altitudinal difference therebetween. The first loading platform21is provided with an active joint211.

The pivot arm component3is composed of a first pivot arm31and a second pivot arm32that are parallel to each other. The first and second pivot arms31,32each have one end pivotally connected to the fixation joint11of the loading component1by means of a pin A or B, and each have an opposite end pivotally connected to the active joint211of the loading platform set2by means of a pin C or D, so that the corresponding ends of the pins A, B, C and D jointly define a parallelogram. The first pivot arm31is provided with a second pivot seat311.

In the present embodiment shown in the drawings, the first and second pivot arms31,32are telescoped, so as to eliminate the risk of mutual interference therebetween in practical operation. In general, the first and second pivot arms31.32can have the lateral walls capable of overlapping with each other; shaft sleeves can be installed on the pivot shafts, so the lateral walls of the first and second pivot arms31,32can be located the inner side and the outer side respectively, and will not interfere with each other during the pivot process; besides, the lateral walls can keep a partially overlapping status during the pivot operation, such that the fingers of the user will not be hurt because of being clamped by the arms.

The damping positioning mechanism4is composed of an adjustable damper41(that may be a gas cylinder with locking function) and a switch42. The adjustment damper41is pivotally connected between the second pivot seat311of the first pivot arm31and the first pivot seat120of the loading component1, and the adjustable damper41is connected to the switch42by means of a control cord43. The switch42may be placed at one side of the second loading platform22and may have an operatable paddle421. When the paddle421is operated, the switch42controls the adjustable damper41to allow it to extend or retract in response to an external force. When the paddle421is released, the adjustable damper41locks itself from extending and retracting.

Referring toFIG. 4, according to the first embodiment of the present invention, during the positional adjustment, when the paddle421is operated, the second loading platform22can be pushed or pressed at the same time by a user, so that the loading platform set2drives the first and second pivot arms31,32to rotate relatively. Throughout the process of the rotation, the imaginary line connecting the pins C and D remains parallel to the imaginary line connecting the pins A and B (holding the parallelogram), so the loading platform set2is restricted to move forward/backward and upward/downward while remaining parallel to the loading component1. With the pivotal movement of the first pivot arm31, the adjustable damper41receives force and is driven to extend or retract.

When the loading platform set2moves to a desire position, the user may release the paddle421, so that the adjustable damper41is locked and prevented from extending and retracting, making the loading platform set2positioned. Thereby, even if the loading platform set2(the first and second loading platforms21and22) receives external force (such as that from a user's palms pressing the second loading platform22when operating a keyboard placed on the second loading platform22), it is unlikely to have unintentional displacement, making its use more convenient.

In general, when the user operates the paddle421, the adjustable damper41usually generates certain damping support forse to the loading platform set2so as to support the weight on the loading platform set2, such that the force for lifting or pressing down provided by the user can be reduced; thus, the user can easily operate the loading platform set2to ascend or descend. Moreover, as shown inFIGS. 5 and 6, the adjustable damper41can further connect to the loading component1or the fixation joint11via an adjustment component12. The adjustment component12majorly includes a first pivot seat120and a lead screw121. The lead screw121is fixed at the loading component1and the first pivot seat120is installed on the lead screw121. By means of the rotation of the lead screw121, the first pivot seat can have relative displacement; when the first pivot seat121moves, the support angle of the adjustable damper41can be changed, so its damping support forse to the loading platform set2can be adjusted. Therefore, the use can adjust the damping support forse according to the load of the loading platform set2to achieve balance between them. In this way, when the user operates the paddle421, the user has no need to lift (the table is too heavy) or press down (the table is too light), such that the use can perform the ascending/descending operations without difficulty.

In a feasible embodiment, the adjustment component12can further connect to an indicator mechanism for showing the adjustable damper41's damping support forse to the loading platform set2as the indicator for the user to adjust. Moreover, the pivotal connection position of the active joint211, and the first and second pivot arms can be further installed with a locking sheet213with three fixation points, which can concentrate the stress and fix the relative position of them. For the reason, the loading platform set2will not be unstable because the arms intersect with each other or due to the stress difference. The following embodiments will provide more detailed description about the technical features of the indicator mechanism and the locking sheet.

Please refer toFIG. 7˜FIG. 11, which shows the second embodiment of the lifting mechanism with support function of the present invention; the mechanism also includes a loading component1′, a loading platform set2′, a pivot arm component3′ and a damping positioning mechanism4, etc. The major difference is that the shape of the pivot arm component3′ is changed, and the loading component1′ has a clamping base14′ capable of being fixed at a default plane or carrier.

More specifically, the loading component1′ is connected to a fixation joint11′ and the loading platform set2′ is connected to an active joint211′. The pivot arm component3′ has a first pivot arm31′ and a second pivot arm32′ parallel to each other. One end of the first and second pivot arms31′,32′ is pivotally connected to the fixation joint11′ and the other end thereof is pivotally connected to the active joint211′; the positions of the pivotal connection shafts can form a parallelogram.

In the embodiment, the loading component1′ include a clamping base14′ and a fixation joint11′; please also refer toFIG. 14, the clamping base14′ can clamp and be fixed at a default object, and have a plurality of arranged locking connection holes140′, such that the fixation joint11′ can connect to the proper position of the clamping base14′ to increase its usability. The loading platform set2′ includes a first loading platform21′, a second loading platform22′ and an extension holder23′ connecting them with each other, so the first and the second loading platforms21′,22′ can be parallel to each other, and have a height difference; the active joint211′ can stably connect to the bottom of the first loading platform211′.

The first and second pivot arms31′,32′ of the pivot arm component3′ are arranged adjacent to each other and sleeved with each other to form an inner hollow space; as shown inFIGS. 8 and 9, the inner sides or the outer sides of the pivotal connection shafts of the first and the second pivot arms31′,32′ are installed with a plurality of shaft sleeves33′, such that the lateral walls310′,320′ of the first and second pivot arms31′,32′ can overlap with each other without interfering with each other during the pivot operation. Further, the lateral walls310′,320′ thereof can keep partially overlapping with each other during the pivot operation, which can prevent foreign objects from entering inside the first and the second pivot arms31′,32′ in order to prevent the user from being accidentally hurt because of being clamped by them. Moreover, so as to increase the stability of the mechanism, a locking sheet213′ can be further installed on the pivotal connection position of the active joint211′, and the first and second pivot arms31′,32′. The locking sheet213′ are fixed at connection board212′ of the active joint211′ by using three pins as the fixation points. The first and second pivot arms31′,32′ are pivotally installed between the connection board212′ and the locking sheet213′, and located at two of the fixation points respectively, such that the stress can be concentrated to fix the relative position; in this way, the loading platform set2′ will not be unstable because the pivot arms intersect with each other or the stress is changed.

Please refer toFIG. 10˜FIG. 13, the damping positioning mechanism4′ mainly includes an adjustable damper41′ and a switch42′; more specifically, one end of the adjustable damper41′ pivotally connects to the second pivot seat311′ of the first pivot arm31′, and the other end thereof pivotally connects to the adjustment component12′ of the fixation joint11′; further, the adjustable damper42′ can connect to the switch42′ via a control cord43′. The adjustment component12′ majorly includes a first pivot seat120′ capable of relatively moving and a lead screw121′ capable of driving the first pivot seat120′. The first pivot seat120′ is installed on the lead screw121′, and the lead screw121′ can be installed in a slot way122′. The lead screw121′ can revolve to drive the first pivot seat120′ to move toward the lead screw121′. The adjustable damper41′ pivotally connects to the first pivot seat120′, so the support angle of the adjustable damper41′ can be changed (as shown inFIG. 11) when the first pivot seat120′ relatively moves so as to change the damping support forse of adjustable damper41′ provided for the loading platform set2′.

When actually using the mechanism, the user can touch the switch42′ to make the adjustable damper41′ be the adjustable status; then, the user can operate the loading platform set2′ to drive the first and second pivot arms31′,32′ to relatively revolve. Besides, during the pivot process, the parallelogram formed by the arrangement of the pivot shafts can make the loading platform set2′ horizontally ascend or descend (as shown inFIG. 12andFIG. 13). After reaching the proper position, the user can release the switch42′ to lock the adjustable damper41′, so the loading platform set2′ can be well positioned. In addition, during the usage process, the user can adjust the lead screw121′ according to the requirements in order to make the damping support forse provided for the loading platform set2′ reach balance with the load. In this way, when performing the ascending/descending operations, the user has no need to apply the lifting force (the table is too heave) or pressing-down force (the table is too light), so the user can easily and conveniently operate the mechanism.

In a feasible embodiment, the adjustment component12′ can connect to an indicator mechanism13′ so as to show the corresponding damping support forse for the user to observe and adjust. In the embodiment, as shown inFIG. 10, the indicator mechanism13′ majorly includes a gear set130′ composed of a first gear131′, a second gear132′ and a third gear133′. The lateral side of the third gear133′ can have a force meter, and which can expose from an opening110′ at the relative position for the user to perform the adjustment according the shown force (corresponding to the load).

Please refer toFIG. 15˜FIG. 18, which show the third embodiment of the lifting mechanism with support function of the present invention; the major changes are the shape of the pivot arm component3″ and the pivotal connection position of the adjustable damper41″. As shown in these figures, the main structure includes a loading component1″, a loading platform set2″, a pivot arm component3″ and a damping positioning mechanism4″.

The loading component1″ is basically a horizontal frame, which can be installed on and fixed at the surface of a common table, or a default carrier; the right side and the left side of which extend upward respectively to form a fixation joint11″ for the pivot arm component3″ to pivotally connect to. The loading platform set2″ includes a first loading platform21″ capable of horizontally load an object, and a second loading platform22″ connecting to the first loading platform21″ via the extension holder23″ to form a height difference. The two sides of the bottom of the first loading platform21″ connect to an active joint211″ for the pivot arm component3″ to connect to.

The pivot arm3″ includes two first pivot arms31″ and two second pivot arms32″ located at two sides thereof respectively. One end of each of the first and second pivot arms31″,32″ connects to the fixation joint11″, and the other end of each of them connects to the active joint211″. The positions of the pivotal connection shafts can substantially form a parallelogram.

In order to keep the stability of the structure, the active joint211″ has a locking sheet213″, and the locking sheet213″ connects to the connection board212″ of the active joint211″ by using three shafts as the fixation points. In this way, the first and second pivot arms31″,32″ can form the intersecting and overlapping status without interfering with each other during the pivot operation, and both of them can keep partially overlapping with each other during the pivot operation so as to reduce the accidents. The locking sheet213″ can concentrate the stress on the pivotal connection point and fix the relative position, so the loading platform set2″ will not be unstable because the arms intersect with each other or due to the stress difference. Similarly, the fixation joint11″ further includes a locking sheet111″ for enhancing the stability between the fixation joint11″, and the first and second pivot arms31″,32″.

In the embodiment, the two sides are respectively installed with a damping positioning mechanism4″, which majorly include an adjustable damper41″ and a switch42″. One end of the adjustable damper41″ is installed on the second pivot arm32″ of the pivot arm component3″, and the other end thereof connects to the active joint211″ via an adjustment component12″. The switch42″ connects to the adjustable damper41″ via a control cord43″ to control the adjustable damper41″ to be the adjustable status or the locked status. The adjustment component12″ mainly includes a first pivot seat120″ and a lead screw121″. The first pivot seat120″ is installed on the lead screw121″, and the adjustable damper41″ connects to the first pivot seat120″. The lead screw121″ can be installed in a slot way122″ and the slot way122″ is fixed at the active joint211″ for further fixation. The lead screw121″ can revolve to drive the first pivot seat120″ to relatively move, and then change the support angle of the adjustable damper41″ connecting to the first pivot seat120″, such that the damping support forse (vertical force component) of the adjustable damper41″ provided for the loading platform set2″ can be adjusted so as to achieve balance with the load and decrease the burden of the descending/ascending operation.

As shown inFIGS. 17 and 18, which show the mechanism is positioned at the high position and the low position respectively. In actual operation, when the switch42″ is operated, the adjustable damper411″ can be adjusted to be the adjustable status (i.e. the adjustable damper41″ can freely extend or retract); at this time, the user can freely operate the loading platform set2″ to ascend or descend so as to adjust it to the desired height; after the adjustment is done, the user can stop pressing the switch42″, and then the adjustable damper41″ returns to the locked status (i.e. the adjustable damper41″ cannot freely extend or retract) in order to fix the loading platform set2″ at the desired height.

According to the previous embodiments, one end of the adjustable damper41″ can be freely and selectively to installed on one of the first pivot arm31″ and the second pivot arm32″ of the pivot arm component3″, and the other end thereof can freely and selectively connect to the loading platform set2″ or the loading component1″.

Further referring toFIGS. 19-23, which show the fourth embodiment of the present invention, the main structure comprises: a loading component5, a loading platform set6, a pivot arm component7and a damping positioning mechanism8. Therein, the loading component5is composed of a guiding post51, a revolver52and a retainer53. The guiding post51has its one end provided with a clamp54configured to hold an external article or table and position the self-positionable lifting device with respect to the article or table. The revolver52and the retainer53are mounted around the middle part of the guiding post51, and the retainer53is fixed below the revolver52. With the retaining force from the retainer53, the revolver52is rotatably positioned at the set altitude on the guiding post51. The revolver52has a fixation joint521and an inner pivot shaft522, and a first pivot seat523is pivotally connected to the inner pivot shaft522.

The loading platform set6is composed of a first loading platform61, a second loading platform62, a pivotable support64and a pivotal connector66. The first and second loading platforms61and62are mutually connected by means of an extension support63, so that the first and second loading platforms61and62are parallel to each other and have an altitudinal difference therebetween.

The pivotal connector66has an active joint661and a pivotal shaft662parallel to the guiding post51. The pivotable support64has its one end connected to the first loading platform61(or the second loading platform62). At the middle part of the pivotable support64, a connector641and an adjustable holder651are provided. The connector641is pivotally mounted around the pivotal shaft662, and the adjustable holder651is adjustablty fixed to the middle part of the pivotable support64. The adjustable holder651is pivotally provided with a mount65that is configured to hold an external device (such as an LCD).

In a feasible embodiment, the first loading platform61is pivotally connected to the terminal of the pivotable support64by means of a first pivot611. The extension support63may be combined with the first loading platform61. The second loading platform62is pivotally connected to the terminal of the extension support63by means of a second pivot621.

The pivot arm component7is composed of a first pivot arm71and a second pivot arm72that are parallel to each other. The first and second pivot arms71and72each have one end pivotally connected to the fixation joint521of the loading component5by means of a E or F, and each have an opposite end pivotally connected to the active joint661of the loading platform set6by means of a pin G or H. The corresponding ends of the pins E, F, G and H jointly define a parallelogramic area. The first pivot arm71is provided with a second pivot seat711.

In the present embodiment shown in the drawings, the first and second pivot arms71,72are telescoped, so as to eliminate the risk of mutual interference therebetween in practical operation.

The damping positioning mechanism8is composed of an adjustable damper81(that may be a gas cylinder with locking function) and a switch82. The adjustable damper81is pivotally connected between the second pivot seat711of the first pivot arm71and the first pivot seat523of the loading component5, and the adjustable damper81is connected to the switch82by means of a control cord83. The switch82may be placed at one side of the second loading platform62and may have an operatable paddle821. When the paddle421is operated, the switch82controls the adjustable damper81to allow it to extend or retract in response to an external force. When the paddle821is released, the adjustable damper81locks itself from extending and retracting.

Referring toFIGS. 21, 22 and 24, according to the fourth embodiment of the present invention, during the positional adjustment, when the paddle821is operation, the second loading platform62can be pushed or pressed at the same time by a user, so that the loading platform set6drives the first and second links71,72to rotate relatively. Throughout the process of the rotation, the imaginary line connecting the pins G and H remains parallel to the imaginary line connecting the pins E and F (holding the parallelogramic area), so the loading platform set6is restricted to move forward/backward and upward/downward while remaining parallel to the loading component5. With the pivotal movement of the first link71, the damper81receives force and is driven to extend or retract.

When the loading platform set6moves to a desire position, the user may release the paddle821, so that the adjustable damper81is locked and prevented from extending and retracting, making the loading platform set6positioned. Thereby, even if the loading platform set6(the first and second loading platforms61and62) receives external force (such as that from a user's palms pressing the second loading platform62when operating a keyboard placed on the second loading platform22), it is unlikely to have unintentional displacement, making its use more convenient.

In practical use, the second loading platform62be folded by pivoting it upward on the second pivot621(as shown inFIG. 21), and the first loading platform61may also be folded by pivoting it upward on the first pivot611(not shown), thereby minimizing the space required for storing the collapsed structure.

In the process that the first and second loading platforms61and62are pushed to move leftward (or rightward), with the pivotable support64(i.e. the connector641) that pivots with respect to the pivotal connector66, and the revolver52that pivots with respect to the guiding post51, the first and second loading platforms61and62can remain facing forward (its initial orientation) without deviating with the pivot arm component7, further improving the convenient use of the present invention.

In a feasible embodiment, the inner pivot shaft522can be a lead screw, and the combination of which and the first pivot seat523can form the adjustment component for adjusting the damping support forse. The inner pivot shaft522can revolve to drive the first pivot seat523to move upward and downward in order to change the support angle of the adjustable damper81connecting to the first pivot seat523, such that the damping support forse of the adjustable damper81provided for the loading platform set6can be adjusted to achieve balance with the load, which can decrease the burden of the descending/ascending operation. Furthermore, as shown inFIGS. 25 and 26, an indicator mechanism55can be provided to connect to the adjustment component, which includes an indicator511connecting to the first pivot seat523and can move upward and downward. The indicator551has a front end552protruding outward, which can show the damping support forse for the user to observe.

To sum up, the mechanism of the present invention can be more convenient, strength-saving and of higher operation stability; besides, the mechanism can freely adjust the damping support forse according to different load requirements, so can significantly increase the convenience in use. The present invention has been described with reference to the preferred embodiments and it is understood that the embodiments are not intended to limit the scope of the present invention. Moreover, as the contents disclosed herein should be readily understood and can be implemented by a person skilled in the art, all equivalent changes or modifications which do not depart from the concept of the present invention should be encompassed by the appended claims.