Self-locking mechanism and lift chair therewith

A self-locking mechanism includes a frame (1), a transmission member (3), a rotating member (2), and a locking rod (4), forming a four-bar linkage mechanism. A supporting member (6) is movable relative to the frame (1). The rotating member (2) has an upper end rotatably connected with the supporting member (6), a lower end provided with a guide slot (22), and a middle portion therebetween. The transmission member (3) has two ends rotatably connected with the frame (1) and the middle portion respectively. The locking rod (4) has an upper end rotatably connected with the frame (1), and a lower end provided with a guide rod (41) movable in the guide slot. The locking rod (4) is rotatable between multiple positions. When the locking rod (4) is in a locking position, the guide rod (41) abuts against the guide slot to prevent the supporting member (6) from moving upward.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This non-provisional application claims priority to and the benefit of, pursuant to 35 U.S.C. § 119(a), patent application Serial Nos. CN201922451035.8 and CN201911392482.9, both filed in China on Dec. 30, 2019. The disclosure of the above applications is incorporated herein in their entireties by reference.

FIELD

The present invention generally relates to a lift chair, and particularly to a self-locking mechanism and a lift chair therewith.

BACKGROUND

Currently, an electronic sofa or a seating furniture is formed by a lift chair metal frame, which functions as the main supporting structure, filled with a filler material (which may be a sponge material or other soft materials) and covered by a covering material (which may be a leather material such as cowhide or cattle hide, or other covering materials), which may be in a luxurious and sophisticated style, and may be widely used in any environment.

A conventional metal frame of an electronic sofa may be formed by a fixed base, a main frame, a supporting member, a backrest member, a footrest member, and a bar linkage mechanism. The main frame is movable relative to the fixed base. The supporting member, the backrest member and the footrest member are all mounted on the main frame through the bar linkage mechanism. By moving the supporting member among different positions relative to the main frame, the bar linkage mechanism may drive the backrest member and the footrest member to move to different positions and to extend or recline ergonomically, allowing the sofa to provide multiple different stances.

FIGS. 1-5shows a conventional lift chair metal frame in different stances. Specifically,FIG. 1shows the metal frame in an assisting stance, where the main frame910moves upward, the supporting member and the backrest member incline forward, and the footrest member moves to a stowed position to assist the user to stand up from the sofa.FIG. 2shows the metal frame in an initial stance, where the main frame910moves downward to a seating position, the supporting member moves to an initial position relative to the main frame910, the backrest member maintains a stowed and relatively vertical position, and the footrest member maintains the stowed position, allowing the user to sit on the sofa in a regular sitting stance.FIG. 3shows the metal frame in a footrest stance, where the footrest member moves to a reclined position, such that the user may put the legs on the footrest member while the upper body of the user maintains a relatively straight position, allowing the user to watch TV or read a book.FIG. 4shows the metal frame in a recreational stance, where the footrest member maintains the reclined position, and the backrest member inclines and extends backward to move to a reclined position, allowing the user to recline on the extended sofa in a reclining or half-lying position.

FIG. 5shows an exemplary bar linkage mechanism of the conventional metal frame. As shown inFIG. 5, the bar linkage mechanism includes a rear rotating member92, a rear transmission member93, a middle member96, a front transmission member97, and a front rotating member98. The rear rotating member92has an upper end rotatably connected with the supporting member91, and a lower end rotatably connected with an upper end of the rear transmission member93. The rear transmission member93has the upper end rotatably connected with the lower end of the rear rotating member92, a middle end rotatably connected with the frame910, and a lower end rotatably connected with the middle member96. The front rotating member98has an upper end rotatably connected with the supporting member91, and a lower end rotatably connected with an upper end of the front transmission member97. The front transmission member97has the upper end rotatably connected with the lower end of the front rotating member98, a middle end rotatably connected with the frame910, and a lower end rotatably connected with the middle member96. The middle member96has two ends rotatably connected with the lower ends of the rear transmission member93and the front transmission member97respectively. In other words, the supporting member91is mounted on the main frame910through the bar linkage mechanism formed by the rear rotating member92, the rear transmission member93, the middle member96, the front transmission member97, and the front rotating member98.

In the conventional metal frame, the supporting member is only locked in the assisting stance as shown inFIG. 1and the initial stance as shown inFIG. 2. Specifically, as shown inFIGS. 1-4, an L-shaped supporting member95is provided between the backrest member and the frame910, and a position limiting pin94is formed at a rear end of the supporting member91. When the metal frame is in the initial stance as shown inFIG. 2, the supporting member91moves to the initial position, and the position limiting pin94hooks the L-shaped supporting member95, facilitating self-locking of the metal frame (where the supporting member91does not move upward, and the footrest member does not extend to the reclined position). When the metal frame is in the self-locking status, the frame910may be lifted to adjust the supporting member91to the assisting stance. In other words, the hook matching of the position limiting pin94and the L-shaped supporting member95allows the metal frame to facilitate self-locking in the initial stance and the assisting stance. However, when the metal frame is in the footrest stance as shown inFIG. 3or the recreational stance as shown inFIG. 4, the position limiting pin94is detached from the L-shaped supporting member95. In this case, if the supporting member91is subject to an upward external force (which may be generated by lifting the footrest member99or by pressing the backrest member), the supporting member91may move to a upward lifting and rotating position, which is not under control of the driving mechanism of the lift chair, creating a safety issue for the user.

SUMMARY

The present invention, in one aspect, relates to a self-locking mechanism used in a lift chair.

In one embodiment, the self-locking mechanism includes: a frame (1), configured to move relative to a base of the lift chair; a supporting member (6), configured to move relative to the frame (1) in a front-rear direction; a rear rotating member (2), having an upper end rotatably connected with the supporting member (6), a lower end provided with a guide slot, and a middle portion between the upper end and the lower end; a rear transmission member (3), having a first end rotatably connected with the frame (1), and a second end rotatably connected with the middle portion of the rear rotating member (2); and a locking rod (4), having an upper end rotatably connected with the frame (1), and a lower end provided with a guide rod (41), wherein the guide rod (41) is movable in the guide slot; wherein the frame (1), the rear transmission member (3), the rear rotating member (2) and the locking rod (4) form a four-bar linkage mechanism; and wherein the locking rod (4) is rotatable between a plurality of positions, the positions include a plurality of locking positions, and when the locking rod (4) is in each of the locking positions, the guide rod (41) abuts against a bottom end of the guide slot to prevent the supporting member (6) from moving upward.

In one embodiment, the first end of the rear transmission member (3) is rotatably connected with the frame (1) through a first rivet (51), the second end of the rear transmission member (3) is rotatably connected with the middle portion of the rear rotating member (2) through a second rivet (52), the upper end of the locking rod (4) is rotatably connected with the frame (1) through a third rivet (53), and axial directions of the first rivet (51), the second rivet (52) and the third rivet (53) are in parallel with one another.

In one embodiment, when the locking rod (4) is in each of the locking positions, the axial directions of the second rivet (52) and the third rivet (53) are collinear.

In one embodiment, the self-locking mechanism further includes a position limiting pin (7) fixed to the frame (1), and when the locking rod (4) is in each of the locking positions, the rear transmission member (3) is in contact with the position limiting pin (7) such that the position limiting pin (7) supports the rear transmission member (3).

In one embodiment, the locking positions include a first locking position and a second locking position; when the locking rod (4) is in the first locking position, the first rivet (51), the third rivet (53) and the guide rod (41) form a self-locking triangular structure, and the supporting member (6) is located at a front side relative to the frame (1); when the locking rod (4) is in the second locking position, the first rivet (51), the third rivet (53) and the guide rod (41) are all aligned along a same line perpendicular to the axial directions, and the supporting member (6) is located at a back side relative to the frame (1); and when the locking rod (4) is in a position between the first locking position and the second locking position, the locking rod (4) prevents the rear rotating member (2) from moving upward, and further prevents the supporting member (6) from moving upward.

In one embodiment, the positions further include an unlocking position, and the second locking position is between the first locking position and the unlocking position; and when the locking rod (4) is in the unlocking position, the axial directions of the second rivet (52) and the third rivet (53) are not collinear, the rear transmission member (3) is not in contact with the position limiting pin (7), and the guide rod (41) does not abut against the bottom end of the guide slot, and the first rivet (51), the third rivet (53) and the guide rod (41) are not all aligned along the same line and do not form the self-locking triangular structure.

In one embodiment, the supporting member (6) is movable between a first position, a second position, a third position and a fourth position; when the supporting member (6) is in the first position or the second position, the locking rod (4) is in the first locking position; when the supporting member (6) is in the third position, the locking rod (4) is in the second locking position; and when the supporting member (6) is in the fourth position, the locking rod (4) is in the unlocking position.

In one embodiment, the self-locking mechanism further includes a spring connecting the frame (1) and the supporting member (6), and when the locking rod (4) is in the unlocking position, the spring is configured to provide a downward elastic force on the supporting member (6) to prevent the supporting member (6) from moving upward.

In another aspect, the present invention relates to a lift chair. In one embodiment, the lift chair includes a base and a self-locking mechanism, and the self-locking mechanism includes: a frame (1), configured to move relative to a base of the lift chair; a supporting member (6), configured to move relative to the frame (1) in a front-rear direction; a rear rotating member (2), having an upper end rotatably connected with the supporting member (6), a lower end provided with a guide slot, and a middle portion between the upper end and the lower end; a rear transmission member (3), having a first end rotatably connected with the frame (1), and a second end rotatably connected with the middle portion of the rear rotating member (2); and a locking rod (4), having an upper end rotatably connected with the frame (1), and a lower end provided with a guide rod (41), wherein the guide rod (41) is movable in the guide slot; wherein the frame (1), the rear transmission member (3), the rear rotating member (2) and the locking rod (4) form a four-bar linkage mechanism; and wherein the locking rod (4) is rotatable between a plurality of positions, the positions include a plurality of locking positions, and when the locking rod (4) is in each of the locking positions, the guide rod (41) abuts against a bottom end of the guide slot to prevent the supporting member (6) from moving upward.

In one embodiment, the first end of the rear transmission member (3) is rotatably connected with the frame (1) through a first rivet (51), the second end of the rear transmission member (3) is rotatably connected with the middle portion of the rear rotating member (2) through a second rivet (52), the upper end of the locking rod (4) is rotatably connected with the frame (1) through a third rivet (53), and axial directions of the first rivet (51), the second rivet (52) and the third rivet (53) are in parallel with one another.

In one embodiment, the self-locking mechanism further includes a position limiting pin (7) fixed to the frame (1), and when the locking rod (4) is in each of the locking positions, the axial directions of the second rivet (52) and the third rivet (53) are collinear, and the rear transmission member (3) is in contact with the position limiting pin (7) such that the position limiting pin (7) supports the rear transmission member (3).

In one embodiment, the locking positions include a first locking position and a second locking position; when the locking rod (4) is in the first locking position, the first rivet (51), the third rivet (53) and the guide rod (41) form a self-locking triangular structure, and the supporting member (6) is located at a front side relative to the frame (1); when the locking rod (4) is in the second locking position, the first rivet (51), the third rivet (53) and the guide rod (41) are all aligned along a same line perpendicular to the axial directions, and the supporting member (6) is located at a back side relative to the frame (1); and when the locking rod (4) is in a position between the first locking position and the second locking position, the locking rod (4) prevents the rear rotating member (2) from moving upward, and further prevents the supporting member (6) from moving upward.

In one embodiment, the positions further include an unlocking position, and the second locking position is between the first locking position and the unlocking position; and when the locking rod (4) is in the unlocking position, the axial directions of the second rivet (52) and the third rivet (53) are not collinear, the rear transmission member (3) is not in contact with the position limiting pin (7), and the guide rod (41) does not abut against the bottom end of the guide slot, and the first rivet (51), the third rivet (53) and the guide rod (41) are not all aligned along the same line and do not form the self-locking triangular structure.

In one embodiment, the supporting member (6) is movable between a first position, a second position, a third position and a fourth position; when the supporting member (6) is in the first position or the second position, the locking rod (4) is in the first locking position; when the supporting member (6) is in the third position, the locking rod (4) is in the second locking position; and when the supporting member (6) is in the fourth position, the locking rod (4) is in the unlocking position.

In one embodiment, the self-locking mechanism further includes a spring connecting the frame (1) and the supporting member (6), and when the locking rod (4) is in the unlocking position, the spring is configured to provide a downward elastic force on the supporting member (6) to prevent the supporting member (6) from moving upward.

DETAILED DESCRIPTION

It will be understood that when an element is referred to as being “on,” “attached” to, “connected” to, “coupled” with, “contacting,” etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on,” “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature. As used herein, “around”, “about”, “substantially” or “approximately” shall generally mean within 20 percent, preferably within 10 percent, and more preferably within 5 percent of a given value or range. Numerical quantities given herein are approximate, meaning that the term “around”, “about” “substantially” or “approximately” can be inferred if not expressly stated.

One aspect of the present invention relates to a self-locking mechanism used in a lift chair. For example,FIGS. 6-13schematically shows a self-locking mechanism according to certain embodiments of the present invention. Specifically,FIGS. 6 and 7show the self-locking mechanism in a first stance (which is an assisting stance, similar to the assisting stance as shown inFIG. 1).FIGS. 8 and 9show the self-locking mechanism in a second stance (which is an initial stance, similar to the initial stance as shown inFIG. 2).FIGS. 10 and 11show the self-locking mechanism in a third stance (which is a footrest stance, similar to the footrest stance as shown inFIG. 3).FIGS. 12 and 13show the self-locking mechanism in a fourth stance (which is a recreational stance, similar to the recreational stance as shown inFIG. 4).

As shown inFIGS. 6-13, the self-locking mechanism includes a frame (1), a rotating member (2), a transmission member (3), a locking rod (4), a supporting member (6) and a position limiting pin (7). Specifically, the frame (1), the rear transmission member (3), the rear rotating member (2) and the locking rod (4) collectively form a four-bar linkage mechanism. It should be noted that the self-locking mechanism may include other additional components for assisting and/or limiting the movement or the rotation of each of the components of the self-locking mechanism, and details of these additional components are not hereinafter elaborated.

The frame (1) is movable relative to a base (82) of the lift chair. In one embodiment, a driving mechanism (84), which may be formed by a linear motor fixed on the base (82) and a driving cylinder connecting the linear motor to the frame (1), is provided to drive the frame (1) to move relative to the base of the lift chair in an obliquely vertical direction (seeFIG. 6).

The supporting member (6) is movable relative to the frame (1) in a substantially front-rear direction, and is used to support the seating portion of the lift chair. In one embodiment, a driving mechanism (not shown) is provided to drive the supporting member (6) to move relative to the frame (1), and the driving mechanism may be similar to the driving mechanism (84) for driving the frame (1), which may include a linear motor and a driving cylinder. In certain embodiments, the supporting member (6) is movable between a first position as shown inFIGS. 6 and 7, a second position as shown inFIGS. 8 and 9, a third position as shown inFIGS. 10 and 11, and a fourth position as shown inFIGS. 12 and 13. In other words, when the supporting member (6) is in the first position, the lift chair is correspondingly in the first stance; when the supporting member (6) is in the second position, the lift chair is correspondingly in the second stance; when the supporting member (6) is in the third position, the lift chair is correspondingly in the third stance; and when the supporting member (6) is in the fourth position, the lift chair is correspondingly in the fourth stance. The first position and the second position are relatively located at a front side relative to the frame (1), and the third position and the fourth position are relatively located at a back side relative to the frame (1).

The rear transmission member (3), the rear rotating member (2) and the locking rod (4) are components of the bar linkage mechanism of the self-locking mechanism.

Specifically, the rear rotating member (2) has an upper end rotatably connected with the supporting member (6), a lower end provided with a guide slot, and a middle portion between the upper end and the lower end. The rear transmission member (3) has a first end rotatably connected with the frame (1) through a first rivet (51), and a second end rotatably connected with the middle portion of the rear rotating member (2) through a second rivet (52). The locking rod (4) has an upper end rotatably connected with the frame (1) through a third rivet (53), and a lower end provided with a guide rod (41). The guide rod (41) is movable in the guide slot, such that the locking rod (4) and the rear rotating member (2) are rotatably and slidably connected through the matching of the guide rod (41) and the guide slot. In one embodiment, axial directions of the first rivet (51), the second rivet (52) and the third rivet (53) are in parallel with one another.

In one embodiment, when the driving mechanism (not shown) drives the supporting member (6) to move relative to the frame (1), the supporting member (6) consequently drives the rear rotating member (2) to rotate, and the rear rotating member (2) drives the rear transmission member (3) and the locking rod (4) to respectively rotate relative to the frame (1). In this case, the frame (1), the rear transmission member (3), the rear rotating member (2) and the locking rod (4) collectively form the four-bar linkage mechanism.

The position limiting pin (7) is fixed to the frame (1) to provide support for the rear transmission member (3) when the self-locking mechanism performs the self-locking function. Specifically, when the self-locking mechanism facilitates self-locking as shown inFIGS. 6-11, the position limiting pin (7) is in contact with the rear transmission member (3) to support the rear transmission member (3), as shown inFIGS. 6, 8 and 10. When the self-locking mechanism is released from self-locking, the position limiting pin (7) is not in contact with the rear transmission member (3), as shown inFIG. 12.

The locking rod (4) is rotatable between multiple positions. In certain embodiments, the positions includes a plurality of locking positions as shown inFIGS. 6-11and at least one unlocking position as shown inFIGS. 12 and 13. Specifically, when the locking rod (4) is in each of the locking positions, the guide rod (41) abuts against a bottom end of the guide slot to prevent the supporting member (6) from moving upward, the axial directions of the second rivet (52) and the third rivet (53) are collinear, and the rear transmission member (3) is in contact with the position limiting pin (7), allowing the self-locking mechanism to facilitate self-locking. When the locking rod (4) is in the unlocking position, the axial directions of the second rivet (52) and the third rivet (53) are not collinear, the rear transmission member (3) is not in contact with the position limiting pin (7), and the guide rod (41) does not abut against the bottom end of the guide slot, and the first rivet (51), the third rivet (53) and the guide rod (41) are not all aligned along the same line and do not form the self-locking triangular structure, such that the self-locking mechanism is released from the self-locking status.

In one embodiment, the locking positions include a first locking position and a second locking position. Specifically, the second locking position is between the first locking position and the unlocking position. When the supporting member (6) is in the first position as shown inFIGS. 6 and 7or the second position as shown inFIGS. 8 and 9, the locking rod (4) is in the first locking position. When the supporting member (6) is in the third position as shown inFIGS. 10 and 11, the locking rod (4) is in the second locking position. When the supporting member (6) is in the fourth position as shown inFIGS. 12 and 13, the locking rod (4) is in the unlocking position.

Specifically, when the lift chair is in the first stance (i.e., the assisting stance) as shown inFIGS. 6 and 7, the frame (1) moves obliquely upward, and the footrest member moves to a stowed position to assist the user to stand up from the lift chair. In this case, the supporting member (6) is in the first position, which is located at a front side relative to the frame (1), and the locking rod (4) is in the first locking position. As shown inFIG. 7, the axial directions of the second rivet (52) and the third rivet (53) are collinear. In other words, the rotation axis of the rear transmission member (3) relative to the rear rotating member (2) and the rotation axis of the locking rod (4) relative to the frame (1) align with each other to form a collinear rotation axis for both the locking rod (4) and the rear transmission member (3). Further, the guide rod (41) abuts against the bottom end of the guide slot to prevent the supporting member (6) from moving upward, and the rear transmission member (3) is in contact with the position limiting pin (7). Thus, the first rivet (51), the third rivet (53) and the guide rod (41) form a self-locking triangular structure, allowing the self-locking mechanism to facilitate self-locking.

When the lift chair is adjusted to the second stance (i.e., the initial stance) as shown inFIGS. 8 and 9, the frame (1) moves downward to a seating position, and the footrest member remains in the stowed position. In this case, the supporting member (6) is in the second position, which is located at a front side relative to the frame (1), and the locking rod (4) remains in the first locking position relative to the frame (1). As shown inFIG. 9, the axial directions of the second rivet (52) and the third rivet (53) remain collinear. In other words, the rotation axis of the rear transmission member (3) relative to the rear rotating member (2) and the rotation axis of the locking rod (4) relative to the frame (1) remain aligning with each other to form a collinear rotation axis for both the locking rod (4) and the rear transmission member (3). Further, the guide rod (41) remains abutting against the bottom end of the guide slot to prevent the supporting member (6) from moving upward, and the rear transmission member (3) is in contact with the position limiting pin (7). Thus, the first rivet (51), the third rivet (53) and the guide rod (41) maintain the self-locking triangular structure, allowing the self-locking mechanism to facilitate self-locking.

When the lift chair is adjusted to the third stance (i.e., the footrest stance) as shown inFIGS. 10 and 11, the footrest member extends and moves to a reclined position, allowing the user to put the legs on the footrest member. In this case, the supporting member (6) correspondingly moves backward to the third position, which is located at a back side relative to the frame (1), and the locking rod (4) rotates counterclockwise to be in the second locking position relative to the frame (1). As shown inFIG. 11, the axial directions of the second rivet (52) and the third rivet (53) remain collinear. In other words, the rotation axis of the rear transmission member (3) relative to the rear rotating member (2) and the rotation axis of the locking rod (4) relative to the frame (1) remain aligning with each other to form a collinear rotation axis for both the locking rod (4) and the rear transmission member (3). Further, the guide rod (41) remains abutting against the bottom end of the guide slot to prevent the supporting member (6) from moving upward, and the rear transmission member (3) is in contact with the position limiting pin (7). Since the locking rod (4) rotates, the first rivet (51), the third rivet (53) and the guide rod (41) are all aligned along a same line perpendicular to the axial directions, allowing the self-locking mechanism to maintain self-locking. In other words, the second locking position of the locking rod (4) is the final locking position.

It should be noted that the positions of the locking rod (4) between the first locking position as shown inFIGS. 6-9and the second locking position as shown inFIGS. 10 and 11form a 90° fan-shaped area, and the self-locking mechanism remains self-locked when the locking rod (4) is located in this 90° fan-shaped area. In other words, any position in this 90° fan-shaped area is a locking position for the locking rod (4). When the locking rod (4) is in a locking position position within this 90° fan-shaped area, the locking rod (4) prevents the rear rotating member (2) from moving upward, and further prevents the supporting member (6) from moving upward. In other words, the locking rod (4) prevents the supporting member (6) from moving upward when the self-locking mechanism is in the first stance (i.e., the assisting stance), the second stance (i.e., the initial stance) or the third stance (i.e., the footrest stance).

When the supporting member (6) is driven to move further backward from the third position to the fourth position, the lift chair is adjusted to the fourth stance (i.e., the recreational stance) as shown inFIGS. 12 and 13, the footrest member maintains in the reclined position, allowing the user to put the legs on the footrest member and the backrest member inclines and extends backward to move to a reclined position, allowing the user to recline on the lift chair in a reclining or half-lying position. In this case, the supporting member (6) is in the fourth position, which is located at a back side relative to the frame (1), and the locking rod (4) further rotates counterclockwise to be in an unlocking position relative to the frame (1). As shown inFIG. 11, as the locking rod (4) further rotates, the first rivet (51), the third rivet (53) and the guide rod (41) are released from being located on the same line, the axial directions of the second rivet (52) and the third rivet (53) are not collinear. In other words, the rotation axis of the rear transmission member (3) relative to the rear rotating member (2) and the rotation axis of the locking rod (4) relative to the frame (1) becomes two different rotation axes. Further, the guide rod (41) is also released from and is thus not in contact with the bottom end of the guide slot (22), and the rear transmission member (3) is not in contact with the position limiting pin (7). Thus, a moving gap exists for the rear rotating member (2), and the self-locking mechanism is released from the self-locking status. In other words, if an upward external force is applied to the supporting member6, the supporting member6may move upward. In one embodiment, the self-locking mechanism further includes a spring (not shown) connecting the frame (1) and the supporting member (6). Thus, when the locking rod (4) is in the unlocking position as shown inFIG. 11, the spring may provide a downward elastic force on the supporting member (6) to prevent the supporting member (6) from moving upward, allowing the supporting member (6) to remain stable in the fourth stance.

In the embodiments as described above, the supporting member (6) may be driven to move between the first position, the second position, the third position and the fourth position in a sequential order, thus switching the lift chair between the first stance (assisting stance), the second stance (initial stance), the third stance (footrest stance) and the fourth stance (recreational stance). Further, the first and second locking positions of the locking rod (4) correspond to the first, second and third stances of the lift chair. In each of the first, second and third stances, the self-locking mechanism remains in the self-locking status, preventing the supporting member (6) from moving upward. Compared to the conventional lift chair style electronic sofa, the self-locking mechanism according to certain embodiments of the present invention further enables self-locking in the third stance when the footrest member extends, allowing the supporting member (6) to remain stable.

In another aspect of the present invention, a lift chair may utilize the self-locking mechanism as described above. As discussed, the lift chair may be switchable between the first stance (assisting stance), the second stance (initial stance), the third stance (footrest stance) and the fourth stance (recreational stance) by driving the supporting member6to move between the first, second, third and fourth positions. In each of the first, second and third stances, the self-locking mechanism remains in the self-locking status, preventing the supporting member (6) from moving upward. Compared to the conventional lift chair style electronic sofa, the lift chair according to certain embodiments of the present invention further enables self-locking in the third stance when the footrest member extends, allowing the supporting member (6) to remain stable.

It should be noted that the lift chair may include other additional components for providing other functions of the lift chair. For example, the lift chair may include a seating portion, a footrest member and a backrest member. Details of these additional components of the lift chair are not hereinafter elaborated.