Mechanical extension device and movable chair unit for movable chairs

Abstract

The present invention relates to a mechanical extension device for a movable chair, the mechanical extension device comprising a seat frame for attaching a seat portion, a backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, and a leg extension device pivotally connected to the front of the seat frame. The mechanical extension device is convertible at least between a seated position and a supine position. Here, during the conversion process of the mechanical extension device from the seated position to the supine position, the rearmost end of the backrest bracket does not have a rearward movement component. According to the present invention, the backrest assembly further comprises a first backrest link and a second backrest link, the first backrest link pivotally connected to the front end of the backrest bracket at a first pivot point and pivotally connected to the seat frame at a second pivot point. The second backrest link pivotally connected to the rear end of the backrest bracket at a third pivot point and pivotally connected to the seat frame at a fourth pivot point. The present invention also relates to a movable chair unit.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 2023107922748 filed on June 30, 2023, and Chinese Patent Application No. 2023111595908 filed on September 8, 2023, and the disclosure content of the above Chinese patent applications is hereby incorporated by reference in its entirety as part of this application.

[0002] The present invention relates to a mechanical stretching device for a movable chair and a movable chair unit including the mechanical leg stretching device.

Background Art

[0003] In the prior art, various types of movable chairs are known, such as sofas or chairs equipped with a multi-position conversion function. With the improvement of people's living standards, the requirements for the comfort of sofas and chairs are also increasing. In known designs, a movable chair unit generally includes a mechanical stretching device, whereby it can be converted between a storage position, a leisure position (also called a TV position), and a lying position. When the chair is converted from the storage position to the leisure position, the footrest of the chair unit extends forward, and the angle between the backrest and the seat part basically does not change. When the chair unit is converted from the leisure position to the lying position, the footrest is lifted further forward and upward than the leisure position, and the backrest is significantly reclined.

[0004] However, with increasing user comfort requirements and a thorough pursuit of zero-wall settings, conventionally designed movable chairs have become insufficient to fully meet user needs. In particular, the complex connections of the mechanical structure and the large number of required parts result in high manufacturing costs, while also leading to stiffness in the mechanical structure during posture changes. Furthermore, such chair units in conventional technology cannot achieve true zero-wall functionality; that is, during the transition from a seated to a supine position, the rear end of the backrest moves backward, requiring a larger movable space behind the chair unit. In addition, during the deployment process of the chair unit, a gap is created between the backrest and the seat, causing the user's jacket to be pulled, thus failing to meet user comfort requirements. [Overview of the project]

[0005] The problem that the present invention aims to solve is to provide a mechanical extension device for a movable chair that is simple in structure and more comfortable, and a corresponding movable chair unit. The chair unit satisfies the user's spatial requirements for zero-wall setting of the movable chair, while also avoiding the occurrence of a gap between the rear edge of the seat and the lower edge of the backrest during the posture change process of the movable chair, thereby achieving a zero-gap design. Furthermore, it prevents the user's jacket from being pulled by an inappropriate relative displacement between the backrest and the seat when the chair is extended, thus providing a comfortable experience without chafing against the back.

[0006] To solve the above problems, the present invention provides a mechanical extension device for a movable chair. A mechanical extension device for a movable chair is A seat frame for attaching the seat, A backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, It includes a leg extension device pivotally connected to the front of the seat frame.

[0007] The mechanical extension device is convertible between at least a seated position and a supine position. In the seated position, the leg extension device is stored below the seat frame. In the supine position, the leg extension device is extended forward and upward, and the backrest bracket is tilted backward. During the conversion of the mechanical extension device from the seated position to the supine position, the rearmost end of the backrest bracket does not have a backward movement component. In some embodiments, the mechanical extension device may be convertible between a seated position, a TV position, and a supine position. In the TV position, the leg extension device is extended forward and upward, while no significant tilt occurs in the backrest bracket.

[0008] In one embodiment of the present invention, the backrest assembly further includes a first backrest link and a second backrest link, the first backrest link being pivotally connected to the front end of the backrest bracket at a first pivot point and pivotally connected to the seat frame at a second pivot point. Furthermore, during the process of converting the mechanical extension device from a seated position to a supine position, the first pivot point has a motion trajectory in the direction of the leg extension device.

[0009] In one selective embodiment of the present invention, the backrest assembly further includes a first backrest link and a second backrest link, the second backrest link being configured as a crank member, the crank member including three pivot points, which are a third pivot point, a fourth pivot point and a fifth pivot point. The third and fifth pivot points are located at the free ends of the upper and lower arms of the crank member, respectively, and the fourth pivot point is located between the third and fifth pivot points. The second backrest link is pivotally connected to the rear end of the backrest bracket at the third pivot point and to the seat frame at the fourth pivot point.

[0010] What needs to be explained here is that the "front-back direction" described in this application refers to the extension direction of the leg extension device of the chair unit or mechanical extension device. Specifically, "front" refers to the direction toward the leg extension device, and "rear" refers to the direction toward the backrest.

[0011] Preferably, the first backrest link and the seat frame form a first angle with the opening facing the leg extension device, and the first angle is smaller in the supine position than in the seated position.

[0012] Preferably, the backrest bracket and the horizontal plane form a second angle in which the opening faces the direction of the leg extension device, and the second angle is at least 20° larger in the supine position than in the seated position, preferably at least 30° larger.

[0013] Preferably, the leg extension device includes a footrest for attaching the footrest, and the footrest is raised 300mm to 400mm higher in the supine position than in the seated position, preferably 320mm to 380mm higher.

[0014] This significantly improves user comfort.

[0015] According to the inventive concept of the present invention, the first backrest link is pivotally connected to the backrest bracket and seat frame at its upper and lower ends, respectively. This additional degree of freedom allows the backrest bracket to move forward relative to the seat frame, thereby optimizing the distance between the mechanical extension device and the wall for the movable chair equipped with this mechanical extension device, and achieving a more thorough zero-wall design. Furthermore, the rear end of the backrest link is connected to the seat frame via only one component, the second backrest link, simplifying the mechanical structure and optimizing the motion characteristics.

[0016] Preferably, the seat frame includes a position regulating portion provided behind the first backrest link, the position regulating portion being capable of supporting the first backrest link so as to prevent the first backrest from swaying in the seated position.

[0017] In this embodiment, the position regulating portion provided on the seat frame effectively restricts or prevents the rearward rotation of the first backrest link. As a result, the rearward displacement component of the backrest bracket from the seated position to the TV position and the supine position is significantly restricted or eliminated, and unfavorable interference with the wall at the rear of the chair is avoided.

[0018] Preferably, the mechanical extension device includes a fixed plate that is fixedly connected to the armrest portion of the movable chair, the rear of which is pivotally connected to one end of a fixed plate link, and a second backrest link is further pivotally connected to the other end of the fixed plate link at a fifth pivot point.

[0019] More preferably, the seat frame is attached to the fixing plate so as to be movable forward and backward by a link mechanism.

[0020] According to the present invention, the link mechanism includes a main link assembly and a sub-link assembly, the main link assembly includes an intermediate link pivotally connected to the sub-link assembly, and during the process of converting the mechanical extension device from a seated position to a supine position, relative displacement occurs between the seat frame and the intermediate link, and between the intermediate link and the fixing plate, in that order.

[0021] More preferably, the link mechanism includes a seat frame connecting rod, the rear end of which is connected to an intermediate link, and the front end of which is connected to a leg extension device.

[0022] To solve the aforementioned problems, the present invention provides a mechanical extension device for a movable chair, A seat frame for attaching the seat, A backrest bracket connected to the rear of the seat frame, The present invention further provides a mechanical extension device, including a leg extension device connected to the front of the seat frame.

[0023] The mechanical extension device is convertible among a seating posture position, a TV posture position, and a lying posture position. In the seating posture position, the leg extension device is stored below the seat frame. In the TV posture position, the leg extension device is lifted forward and upward. In the lying posture position, the leg extension device is lifted forward and upward, the backrest bracket is tilted backward, and during the conversion of the mechanical extension device from the seating posture position to the TV posture position and to the lying posture position, the rearmost end of the backrest bracket has a forward movement component.

[0024] In one embodiment according to the present invention, the backrest bracket is connected to the seat frame via a first backrest link and a second backrest link. The upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear part of the seat frame at a second pivot point. During the conversion of the mechanical extension device from the seating posture position to the lying posture position, the first pivot point has a movement locus in the horizontal direction toward the direction of the leg extension device and a movement locus in the height direction from downward to upward.

[0025] In this embodiment, during the conversion from the seating posture position to the lying posture position, due to the action of the seat frame on the first pivot point, both the backrest bracket and the backrest attached thereto are moved together with the first pivot point in the direction of the leg extension device, that is, moved forward. Also, since the first pivot point has a stage of moving from downward to forward in the height direction, inappropriate separation movement between the backrest and the seat portion is avoided. As a result, there is no gap between the backrest and the seat portion, preventing the sandwiching of foreign objects, improving safety, while avoiding the user's upper garment being pulled by the backrest, and improving the comfort of use.

[0026] In one alternative embodiment according to the present invention, the backrest bracket is connected to the seat frame via a first backrest link and a second backrest link. The upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear part of the seat frame at a second pivot point. The distance between the first pivot point and the second pivot point is 80 mm to 150 mm, and a first included angle formed by the first backrest link and the seat frame, with the opening facing the direction of the leg extension device, is less than 90°.

[0027] Preferably, the distance between the first pivot point and the second pivot point is 100 mm to 140 mm, and particularly preferably, it is 115 mm to 120 mm.

[0028] In this alternative embodiment, from the aspects of structural design and connection relationship, the first backrest link is optimized. The included angle formed by the first backrest link and the seat frame, which faces the leg extension device, is always less than 90°, that is, it is always an acute angle. Therefore, when the first backrest link has appropriate dimensions, during the conversion process from the sitting position to the lying position, the first backrest link connected between the front end of the backrest bracket and the seat frame is further pushed down when the backrest bracket moves forward. That is, the upper end of the first backrest link is further tilted forward and inverted around the second pivot point. As a result, the forward movement of the backrest bracket is promoted, and thus a complete zero-wall is realized in the posture conversion process from the sitting position to the lying position. On the other hand, this also avoids jamming during the posture conversion process, so the operation becomes smoother and the functional reliability is improved.

[0029] Preferably, at the lying position, the first pivot point is higher than that at the sitting position.

[0030] Preferably, during the transition of the mechanical extension device from a seated position to a TV position, the first pivot point moves forward and downward, and during the transition of the mechanical extension device from a TV position to a supine position, the first pivot point moves forward and upward.

[0031] Preferably, the second pivot link is pivotally connected to the rear end of the backrest bracket at the third pivot point and to the rear of the seat frame at the fourth pivot point, with the fourth pivot point being located later than the second pivot point.

[0032] Preferably, during the process of converting the mechanical extension device from a seated position to a TV position, the rear end of the seat frame is lowered relative to the fixing plate, and during the process of converting the mechanical extension device from a TV position to a supine position, the seat frame is raised relative to the fixing plate.

[0033] More preferably, the second backrest link is configured as a crank member and further includes a fifth pivot point, the third and fifth pivot points being located at the free ends of the upper and lower arms of the crank member, respectively, the fourth pivot point being located between the third and fifth pivot points, and the second backrest link being directly or indirectly connected to the fixing plate at the fifth pivot point.

[0034] According to the present invention, the seat frame is attached to the fixed plate so as to be movable forward and backward by a main interlocking assembly and a sub-interlocking assembly, the seat frame is pivotally connected to the main interlocking assembly, and the sub-interlocking assembly is pivotally connected to the fixed plate.

[0035] More preferably, the main linkage assembly includes an intermediate link pivotally connected to a sub-linkage assembly, wherein during the conversion of the mechanical extension device from a seated position to a TV position, the rear end of the seat frame is moved downward and forward relative to the intermediate link by the main linkage assembly, the intermediate link has no relative displacement with respect to the fixed plate, and during the conversion of the mechanical extension device from a TV position to a supine position, the seat frame is moved forward and upward relative to the fixed plate together with the main linkage assembly by the sub-linkage assembly.

[0036] Preferably, the mechanical extension device according to the present invention is used in a movable chair with floor-standing armrests. However, selectively, the mechanical extension device can be applied to movable chairs of other structures in a reasonable manner.

[0037] In one preferred embodiment, the mechanical extension device further includes a linear electric actuator device. However, in an optional embodiment, the mechanical extension device may be manually operated, or a combination of manual and motor-driven operation.

[0038] To solve the above problems, the present invention provides a movable chair unit, It includes an armrest, a backrest, a seat, a footrest, and a mechanical extension device. The mechanical extension device is, A seat frame for attaching the seat, A backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, It includes a leg extension device pivotally connected to the front of the seat frame and for attaching the footrest, The mechanical extension device allows the chair unit to be converted between at least a seated position and a supine position, in the seated position the footrest is stored below the seat frame, and in the supine position the footrest is extended forward and upward and the backrest is tilted backward, and during the conversion process of the chair unit from the seated position to the supine position, the rearmost end of the backrest does not have a rearward movement component when viewed along the front-to-back direction of the chair unit.

[0039] In one embodiment of the present invention, the backrest assembly further includes a first backrest link and a second backrest link, the first backrest link being pivotally connected to the front end of the backrest bracket at a first pivot point and pivotally connected to the seat frame at a second pivot point, and during the process of converting the mechanical extension device from a seated position to a supine position, the first pivot point has a motion trajectory in the direction of the leg extension device.

[0040] In one selective embodiment of the present invention, the backrest assembly further includes a first backrest link and a second backrest link, the second backrest link being configured as a crank member, the crank member including three pivot points, which are a third pivot point, a fourth pivot point and a fifth pivot point. The third and fifth pivot points are located at the free ends of the upper and lower arms of the crank member, respectively, and the fourth pivot point is located between the third and fifth pivot points. The second backrest link is pivotally connected to the rear end of the backrest bracket at the third pivot point and to the seat frame at the fourth pivot point.

[0041] Preferably, the first backrest link and the seat frame form a first angle with the opening facing the leg extension device, and the first angle is smaller in the supine position than in the seated position.

[0042] Preferably, the backrest bracket and the horizontal plane form a second angle in which the opening faces the direction of the leg extension device, and the second angle is at least 20° larger in the supine position than in the seated position, preferably at least 30° larger.

[0043] Preferably, the leg extension device includes a footrest for attaching the footrest, and the footrest is raised 300mm to 400mm higher in the supine position than in the seated position, preferably 320mm to 380mm higher.

[0044] Preferably, the seat frame includes a position regulating portion provided behind the first backrest link, the position regulating portion being capable of supporting the first backrest link so as to prevent the first backrest link from swaying in the seated position.

[0045] Preferably, the mechanical extension device includes a fixed plate fixedly connected to the armrest portion, the rear of which is pivotally connected to one end of a fixed plate link, and a second backrest link is further pivotally connected to the other end of the fixed plate link at a fifth pivot point.

[0046] Preferably, the seat frame is attached to the fixing plate so as to be movable forward and backward relative to the armrest portion by a link mechanism.

[0047] Preferably, the link mechanism includes a main link assembly and a sub-link assembly, the main link assembly includes an intermediate link pivotally connected to the sub-link assembly, and during the process of converting the chair unit from a seated position to a supine position, relative displacement occurs between the seat frame and the intermediate link, and between the intermediate link and the fixing plate, in that order.

[0048] Preferably, the link mechanism includes a seat frame connecting rod, the rear end of which is connected to an intermediate link, and the front end of which is connected to a leg extension device.

[0049] To solve the above problems, the present invention provides a movable chair unit, It includes an armrest, a backrest, a seat, a footrest, and a mechanical extension device. The mechanical extension device is, A seat frame for attaching the seat, A backrest bracket for attaching the backrest, The present invention further provides a movable chair unit, which includes a leg extension device pivotally connected to the front of the seat frame and for attaching a footrest.

[0050] The mechanical extension device allows the chair unit to be converted between a seated position, a TV position, and a supine position. In the seated position, the footrest is stored below the seat frame. In the TV position, the footrest is raised forward and upward. In the supine position, the footrest is raised forward and upward, and the backrest is tilted backward. During the process of the chair unit being converted from the seated position to the TV position and then to the supine position, the rearmost end of the backrest has a forward movement component.

[0051] In one embodiment of the present invention, the backrest bracket is connected to the rear of the seat frame via a first backrest link and a second backrest link, the upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear of the seat frame at a second pivot point, and during the process of converting the chair unit from a seated position to a supine position, the first pivot point has a horizontal motion trajectory toward the leg extension device and a vertical motion trajectory toward downward and then upward.

[0052] In one selective embodiment of the present invention, the backrest bracket is connected to the rear of the seat frame via a first backrest link and a second backrest link, the upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear of the seat frame at a second pivot point, the distance between the first pivot point and the second pivot point is 80 mm to 150 mm, and the first angle formed by the first backrest link and the seat frame, the first angle in which the opening faces the direction of the leg extension device, is less than 90°.

[0053] Preferably, the first pivot point is higher in the supine position than in the seated position.

[0054] Preferably, during the transition of the chair unit from a seated position to a TV viewing position, the first pivot point moves forward and downward, and during the transition of the chair unit from a TV viewing position to a supine position, the first pivot point moves forward and upward.

[0055] Preferably, the second pivot link is pivotally connected to the rear end of the backrest bracket at the third pivot point and to the rear of the seat frame at the fourth pivot point, with the fourth pivot point being located later than the second pivot point.

[0056] Preferably, the mechanical extension device includes a fixing plate that is fixedly connected to the armrest portion of the movable chair, the rear end of the seat frame is lowered relative to the fixing plate, and the seat frame is raised relative to the fixing plate during the process of converting the chair unit from a TV posture position to a supine posture position.

[0057] Preferably, the second backrest link is configured as a crank member and further includes a fifth pivot point, the third and fifth pivot points being located at the free ends of the upper and lower arms of the crank member, respectively, the fourth pivot point being located between the third and fifth pivot points, and the second backrest link being directly or indirectly connected to the fixing plate at the fifth pivot point.

[0058] Preferably, the seat frame is attached to the fixed plate so as to be movable forward and backward by a main interlocking assembly and a sub-interlocking assembly, the seat frame is pivotally connected to the main interlocking assembly, and the sub-interlocking assembly is pivotally connected to the fixed plate.

[0059] Preferably, the main interlocking assembly includes an intermediate link pivotally connected to a sub-interlocking assembly, and during the process of converting the chair unit from a seated position to a TV position, the rear end of the seat frame is moved downward and forward relative to the intermediate link by the main interlocking assembly, the intermediate link has no relative displacement with respect to the fixed plate, and during the process of converting the chair unit from a TV position to a supine position, the seat frame is moved forward and upward relative to the fixed plate together with the main interlocking assembly by the sub-interlocking assembly.

[0060] Preferably, the chair unit is a floor-standing chair unit with armrests.

[0061] Preferably, the chair unit further includes a linear electric actuator device.

[0062] The advantages described above regarding the mechanical extension device also apply to a movable chair unit having the same mechanical extension device. [Brief explanation of the drawing]

[0063] Embodiments of the present invention will be described in detail below with reference to the drawings. [Figure 1] This is a schematic diagram showing a mechanical extension device for a movable chair according to one embodiment of the present invention, with the mechanical extension device in a seated position. [Figure 2] A mechanical extension device for a movable chair according to one embodiment of the present invention is schematically shown in another perspective view as a mechanical extension device in a seated position. [Figure 3] Figure 2 is a schematic perspective view showing the TV posture position of the mechanical extension device. [Figure 4] Figure 2 is a schematic perspective view showing the supine position of the mechanical extension device. [Figure 5] This diagram schematically shows the seated position of a mechanical extension device according to one embodiment of the present invention in the form of a side view. [Figure 6]Figure 5 schematically shows the TV posture position of the mechanical extension device in a side view. [Figure 7] Figure 5 schematically shows the supine position of the mechanical extension device in a side view. [Figure 8] This is a schematic partial side view showing a mechanical extension device according to one embodiment of the present invention. [Figure 9] This diagram schematically illustrates the seated position of a mechanical extension device with a backrest in a movable chair. [Figure 10] This diagram schematically shows the supine position of a mechanical extension device with a backrest for a movable chair. [Figure 11] This diagram shows a schematic representation of the posture change mechanism of the mechanical extension device according to the present invention.

[0064] The following describes the technical aspects of embodiments of the present invention clearly and completely with reference to the drawings of the embodiments of the present invention, but it is clear that the embodiments described are only some, and not all, embodiments of the present invention. Any other embodiments that can be obtained without creative work by those skilled in the art based on the embodiments of the present invention are all included within the scope of the protection of the present invention.

[0065] The terms "one embodiment" or "embodiment" as used herein refer to specific features, structures, or characteristics that may be included in at least one realization of the present invention. In the description of the present invention, it should be understood that orientations or positional relationships indicated by terms such as "up," "down," "left," "right," "top," and "bottom" are based on the orientations or positional relationships shown in the drawings and are used to facilitate the description of the present invention and simplify the explanation, but do not indicate or imply that the indicated devices or elements must have a specific orientation or must be constructed and operated in a specific orientation, and should not be understood as limitations on the present invention. Furthermore, the terms "first" and "second" are for descriptive purposes only and do not indicate or imply relative importance, nor do they implicitly indicate the quantity of the indicated technical features. Therefore, features limited by "first" and "second" may explicitly or implicitly include one or more such features. Moreover, terms such as "first" and "second" are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The data used in this manner are interchangeable with each other in appropriate circumstances, and it should be understood that the embodiments of the present invention described herein can be implemented in an order other than that illustrated or described herein.

[0066] Figures 1 to 4 show a perspective view of the mechanical extension device 1 for a movable chair according to the present invention, which includes a multi-link mechanism and is structured to allow the movable chair to be converted between a seated position, a TV position, and a supine position. However, the present invention is not limited thereto. In other embodiments not shown, the movable chair may be converted only between the stowed position and the TV position, or only between the stowed position and the supine position.

[0067] As shown in Figures 1 to 4, the mechanical extension device is constructed for use in a floor-mounted movable chair with armrests and includes two mechanical extension device halves, one on each side, arranged symmetrically in a mirror image. Each mechanical extension device half has a fixed plate 12 that extends vertically along the front-to-back direction of the movable chair, and each mechanical extension device half is set via its respective fixed plate 12 to an inner plate of the armrest section (not shown in Figure 1). Each fixed plate 12 is attached via a fixed tab 51 to a common fixed crossbeam 52, which is located on the backrest side, i.e., at the rear of the movable chair. The bottom of the armrest section is directly supported by the ground, so the mechanical extension device is supported above the ground in a "suspended" manner.

[0068] The mechanical extension device 1 further includes a seat frame 10, a backrest assembly 2 pivotably connected to the rear of the seat frame 10, and a leg extension device 3 pivotably connected to the front of the seat frame 10.

[0069] The seat frame 10 is for supporting the seat portion of a movable chair, and the seat frame 10 includes a rear extension portion 11 that is fixedly provided at its rear end and extends upward. The rear extension portion 11 may be integrally molded with the seat frame 10, or it may be fixedly connected to the seat frame 10 as a separate part, and may be fixedly attached to the seat frame 10 by methods such as welding or riveting.

[0070] The backrest assembly 2 includes a backrest bracket 21, a first backrest link 22, and a second backrest link 23 for attaching the backrest of the movable chair. The backrest bracket 21 has a substantially L-shaped structure, with its front end pivotably connected to the upper end of the first backrest link 22 at a first pivot point P1, and the lower end of the first backrest link 22 pivotally connected to the rear of the seat frame 10 at a second pivot point P2. The second backrest link 23 is configured as a crank member and has three pivot points, one in the middle of the crank member and one at the ends of both arms. Specifically, the second backrest link 23 is pivotally connected to the rear end of the backrest bracket 21 at a third pivot point P3 via its upper end, and the second backrest link 23 is pivotally connected to the upper end of the rear extension 11 of the seat frame at a fourth pivot point P4 via its middle. The fourth pivot point P4 is located after the second pivot point P2. This forms a single four-link mechanism with the backrest bracket 21, the seat frame 10, and the first backrest link 22 and second backrest link 23 connecting the two. The lower end of the second backrest link 23 is pivotably connected to the upper end of the fixed plate link 24 at the fifth pivot point P5, and the lower end of the fixed plate link 24 is pivotably connected to the rear of the fixed plate 12.

[0071] Figure 8 shows a side view detailing the backrest assembly. The distance L between the first pivot point P1 and the second pivot point P2 of the first backrest link 22 is in the range of 80 mm to 150 mm, preferably 100 mm to 140 mm, and in the embodiments shown in Figures 1 to 8, a particularly preferred choice is that the distance L between the first pivot point P1 and the second pivot point P2 is selected to be 115 mm to 120 mm. The first backrest link 22 and the seat frame 10 form a first angle α whose opening faces the leg extension device 3, and this first angle is acute. Furthermore, the distance between the third pivot point P3 and the fourth pivot point P4 of the second backrest link 23 may be 45 mm to 90 mm, and in this embodiment, it may be selected to be 60 mm to 80 mm. The distance between the fourth pivot point P4 and the fifth pivot point P5 may be 85 mm to 200 mm, and in this embodiment, it may be selected to be 120 mm to 160 mm.

[0072] As described above, the fixing plate 12 of the mechanical extension device 1 is fixedly attached to an armrest (not shown). The seat frame 10 is movably connected to the fixing plate 12 via a link assembly. The link assembly includes a main linkage assembly and a sub-linkage assembly, the main linkage assembly including at least a front swing rod 13, a rear swing rod 14, and an intermediate link 15, and the sub-linkage assembly including at least a sub-front swing rod 17, a sub-rear swing rod 18, and a sub-intermediate link 19a. The main linkage assembly is for moving the seat frame 10 back and forth relative to the intermediate link 15 during the process of the chair unit being converted between a seated position and a TV position, while the intermediate link 15 remains essentially unchanged in position relative to the armrest. The sub-linkage assembly is for moving the seat frame back and forth relative to the armrest together with the main linkage assembly during the process of the chair unit being converted between a TV position and a supine position. Specifically, the main linkage assembly drives the seat frame 10 to move forward and downward relative to the intermediate link 15 during the process of converting the chair unit from a seated position to a TV position, and at the same time, the intermediate link 15 has basically no relative movement with respect to the armrest portion and the fixing plate 12. The secondary linkage assembly drives the seat frame 10 to move forward and upward relative to the armrest portion together with the main linkage assembly during the process of converting the chair unit from a TV position to a supine position.

[0073] The upper ends of the front swing rod 13 and the rear swing rod 14 are pivotally connected to the seat frame 10, and the intermediate link 15 is pivotally connected between the front swing rod 13 and the rear swing rod 14. Furthermore, the seat frame connecting rod 16 is pivotally connected between the front end of the intermediate link 15 and the seat frame 10. Thus, the seat frame 10, the front swing rod 13, the rear swing rod 14, and the intermediate link 15 constitute a single four-link mechanism. When the leg extension device 3 begins to extend from the seated position by the action of the linear electric drive device, the seat frame 10 moves forward, and the front swing rod 13 and the rear swing rod 14 are tilted forward around their respective pivot points on the intermediate link 15.

[0074] The lower ends of the sub-front swing rod 17 and the sub-rear swing rod 18 are pivotally connected to the fixing plate 12. The upper end of the sub-front linking rod 17a is pivotally connected to the upper end of the sub-front swing rod 17, and the lower end is pivotally connected to the front of the intermediate link 15. The upper end of the sub-rear linking rod 18a is pivotally connected to the upper end of the sub-rear swing rod 18, and the lower end is pivotally connected to the rear of the intermediate link 15.

[0075] The rear end of the sub-intermediate link 19a is pivotally connected to the middle part of the sub-rear connecting rod 18a, the front end of the sub-intermediate link 19a is pivotally connected to the top end of the sub-front swing rod 17, and a driven link 19b is pivotally connected between the middle part of the sub-intermediate link 19a and the top end of the sub-rear swing rod 18.

[0076] As a result, the intermediate link 15 is lifted and supported by the fixing plate 12 so that it can move back and forth, by the sub-front swing rod 17, sub-front connecting rod 17a, and sub-rear swing rod 18, and sub-rear connecting rod 18a.

[0077] When the seat frame linkage rod 16 is moved forward to its limit position, that is, when it reaches the TV posture position shown in Figure 3, if the linear electric drive continues to act in the same direction, the intermediate link 15 is moved forward together with the seat frame 10, and as a result, the sub-front swing rod 17 and the sub-rear swing rod 18 pivot forward and tilt around their lower ends and the pivot point of the fixing plate 12, respectively.

[0078] The leg extension device 3 includes a first extension section 31, a second extension section 32, and a footrest 33 for attaching the footrest section. The first extension section 31 includes a first link 311 and a second link 312. The second link 312 is provided with a position regulating groove 3120. The second extension section 32 includes a third link 321 and a fourth link 322. The fourth link 322 includes a position regulating pin 3220. The first link 311 is rotatably connected to the fourth link 322, and the second link 312 is rotatably connected to the third link 321. The footrest 33 includes a connecting end face 331 and an end face 332. Of these, both the first link 311 and the second link 312 are rotatably mounted on the seat frame 10, and the pivot point between the first link 311 and the seat frame 10 is located behind the pivot point between the second link 312 and the seat frame 10. The footrest 33 is pivotally connected to the third link 321 and the fourth link 322. When the leg extension device 3 is deployed, that is, in the TV posture position shown in Figure 2 and the supine posture position shown in Figure 3, the second link 312 is extended forward of the first link 311.

[0079] As shown in Figures 2 and 3, a return spring device may be further provided between the link assembly and the inner plate to assist in returning to the original position after a change in attitude.

[0080] The mechanical extension device 1 further includes a linear electric actuator device 4, which includes a motor head 41 and a motor push rod 42 that is extendable and retractable relative to the motor head 41. The motor head 41 is mounted so as to be fixed in position relative to the armrest portion. For example, in the embodiments shown in Figures 1 to 4, the motor head 41 is pivotably connected to a motor head bracket 41a, which is fixedly mounted to a fixed crossbeam 52. Here, the motor head bracket 41a does not have a forward-reverse motion component during the process of the chair unit being converted between a seated position and a supine position, but is capable of pivoting around an axis that is lateral to the forward-reverse direction. The motor push rod 42 acts on a front drive pipe 44 that is laterally connected between the second links 312 of the leg extension device 3. Of course, in embodiments not shown, the positions of the motor head 41 and the motor push rod 42 may be reversed. As shown in Figure 1, the motor push rod 42 is attached to the front drive pipe 44 via the motor bracket 43, the motor push rod 42 is pivotally connected to the motor bracket 43, and the motor bracket 43 is fixedly connected to the front drive pipe 44.

[0081] If you want to change the chair unit from the seated position shown in Figures 2 and 5 to the TV position shown in Figures 3 and 6, the mechanical extension device 1 begins to extend due to the action of the linear electric actuator device 4, and the motor push rod 42 extends relative to the motor head 41, pushing the second link 312 of the leg extension device 3 forward, thereby moving the seat frame 10 forward, tilting the front swing rod 13 and rear swing rod 14 forward, and as a result the TV position shown in Figures 3 and 6 is achieved. In this process, as the seat frame 10 moves horizontally toward the leg extension device 3, that is, forward, the first backrest link 22 pivots slightly backward around the second pivot point P2 at its lower end, that is, tends to rotate clockwise in the figures. To this end, the seat frame 10 is provided with a first position restricting section 101 located behind the first backrest link 22, which allows the first backrest link 22 to be supported from the rear, preventing the first backrest link 22 from swaying in the seated position and maintaining stable support for the backrest bracket 21. In this case, the backrest bracket 21, the first backrest link 22, and the second backrest link 23 move forward horizontally together with the seat frame 10 and the rear extension section 11 of the seat frame, causing the fixing plate link 24 to rotate forward around its lower end and the pivot point of the fixing plate 12. At the same time, the front swing rod 13 and the rear swing rod 14 are tilted forward, causing the seat frame 10, particularly the rear end of the seat frame 10, to descend along the height direction.

[0082] Furthermore, during the transition from a seated position to a TV position, the entire backrest bracket 21 is moved forward by the seat frame 10, so the rearmost endpoint of the backrest bracket 21 has a forward movement component. At the same time, the first pivot point P1 between the backrest bracket 21 and the first backrest link 22 has a forward movement trajectory in the horizontal direction. Also, since the rear end of the seat frame 10 descends along the height direction, the first pivot point P1 also has a downward movement trajectory in the height direction.

[0083] If you want to change the chair unit from the TV posture position shown in Figures 3 and 6 to the reclining posture position shown in Figures 4 and 7, the motor push rod 42 is further extended relative to the motor head 41, the seat frame 10 is moved forward by the leg extension device 3, the front swing rod 13 and rear swing rod 14 are tilted forward to their limit positions, and the intermediate link 15 is moved forward together with the seat frame 10 and simultaneously lifted upward, thereby causing the sub-front swing rod 17 and sub-rear swing rod 18 to pivot forward and tilt around their lower ends and the pivot point of the fixing plate 12, respectively. Furthermore, the second backrest link 23 rotates counterclockwise around the fifth pivot point P5, to which its lower end is hinged to the fixed plate link 24, and tilts toward the direction of the leg extension device. This reduces the height difference between its upper end and the fourth pivot point P4 in the middle, further pushing the entire backrest bracket 21 forward and tilting the upper part of the backrest bracket 21 further backward, reducing the angle between the first backrest link 22 and the seat frame 10. As a result, the reclining position shown in Figures 4 and 7 is achieved. In this process, the backrest bracket 21 reclines and pivots clockwise around the third pivot point P3. However, while the seat frame 10 itself moves forward, the backrest bracket 21 also moves forward relative to the seat frame 10 simultaneously through the coordinated action of the first backrest link 22 and the second backrest link 23. Therefore, both the first pivot point P1 of the backrest bracket 21 and the furthest rearmost endpoint of the backrest bracket 21 have a forward movement trajectory.

[0084] Figures 9 and 10 schematically show embodiments of a chair unit in a seated and supine position, respectively. For simplification, only the mechanical extension mechanism and backrest of the chair unit are shown, and the wall located behind the chair unit and the horizontally oriented ground are schematically shown.

[0085] During the transition from the seated position shown in Figure 9 to the supine position shown in Figure 10, the rearmost end of the backrest bracket 21 moves significantly forward when viewed along the front-to-back direction of the chair unit, while the rearmost end of the backrest does not move backward and always remains in close contact with the wall behind it. Therefore, during this process, the backrest only descends in the height direction. On the other hand, in possible embodiments not shown, the rearmost end of the backrest may move forward during the transition from the seated position to the supine position.

[0086] Figure 11 schematically illustrates the posture changes between the seated, TV-watching, and supine positions of the mechanical extension device according to the present invention. The fixing plate 12 is fixedly attached to the armrest portion of the chair unit. For a clearer illustration, the vertical plane where the rearmost end of the fixing plate 12 is located is designated as the first horizontal reference plane E1, and the horizontal plane where the lower region of the fixing plate 12 is located is designated as the second reference plane E2. During the posture change process, both the first reference plane E1 and the second reference plane E2 remain fixed in position relative to the floor-standing armrest portion of the chair unit. Figure 8 shows the seated position of the mechanical extension device in the upper section, the TV-watching position of the mechanical extension device in the middle section, and the supine position of the mechanical extension device in the lower section.

[0087] The front side of the first backrest link 22 forms a first angle α facing forward with the top surface of the seat frame 10, that is, a first angle α opening toward the direction of the leg extension device, the backrest bracket 21 and the second reference plane E2 form a second angle β facing forward, and the first pivot point P1 between the backrest bracket 21 and the first backrest link 22 has vertical heights of H1, H2, and H3 from the second reference plane E1 in the seated position, TV position, and supine position, respectively.

[0088] During the transition from a seated position to a supine position, the first included angle α decreases significantly, while the second included angle β increases significantly, with the second included angle β increasing by at least 20°.

[0089] In one preferred embodiment, during the transition from a seated position to a supine position, the first included angle α is always less than 90°, and furthermore, the first included angle α is significantly smaller in the supine position than in the seated position, while the second included angle β is significantly larger.

[0090] The footrest is raised 300mm to 400mm higher in the supine position than in the seated position, preferably 320mm to 380mm higher. This significantly improves the user's comfort.

[0091] During the transition from the seated position to the TV position, the front swing rod 13 and rear swing rod 14 pivot forward, while the intermediate link 15 has no relative movement with respect to the fixed plate 12. As a result, the seat frame 10 moves forward, while the rear end of the seat frame 10 is lowered. Simultaneously, the first pivot point P1 moves forward horizontally, while it is lowered vertically along with the rear end of the seat frame 10. Therefore, the height H2 of the first pivot point P1 in the TV position is smaller than its height H1 in the seated position.

[0092] During the transition from the TV viewing position to the supine position, the intermediate link 15 moves forward and upward relative to the fixing plate 12 together with the seat frame 10, and the backrest bracket 21 moves forward and upward using the first backrest link 22. As a result, the first pivot point P1 moves forward and upward, so that the height H3 of the first pivot point P1 in the supine position is greater than the height H2 in the TV viewing position. By selecting an appropriate length for the first backrest link 22, the height H3 of the first pivot point P1 in the supine position can be made greater than its height H1 in the seated position. In this process, since the first angle α is less than 90°, it is advantageous for the first backrest link 22 to be inverted and tilted forward counterclockwise around the second pivot point P2, while not interfering with or hindering the lifting of the seat frame 10.

[0093] The above description has already sufficiently presented specific embodiments of the present invention. It should be noted that any modifications made by those skilled in the art to specific embodiments of the present invention do not depart from the scope of the claims of the present invention. Accordingly, the scope of the claims of the present invention is not limited to the specific embodiments described above. [Explanation of Symbols]

[0094] 1 Mechanical stretching device 10 seat frames 101 First position regulation section 11 Seat frame rear extension 12 Fixed plate 13 Front Swing Rod 14 Rear swing rod 15 Intermediate Links 16 Seat frame connecting rod 17. Sub-front swing rod 17a Sub-front connecting rod 18. Sub-rear swing rod 18a Sub-rear connecting rod 19a Sub-intermediate link 19b Driven link 2 Backrest Assembly 21 Backrest Bracket 22 First backrest link 23 Second backrest link 24 Fixed plate links 3 Leg extension device 31 First extension part 311 First Link 312 Second Link 3120 Positioning groove 32 Second extension part 321 Third Link 322 Fourth Link 3220 Positioning pin 33 Foot Total 331 Connection end face 332 End surface 4. Linear Electric Actuator Device 41 Motorhead 41a Motor head bracket 42 Motor pushrod 43 Motor bracket 44 Front drive pipe 51 Fixed tabs 52 Fixed crossbeam P1 First pivot point P2 Second pivot point P3 Third pivot point P4 Fourth pivot point P5 Fifth pivot point E1 First reference plane E2 Second reference plane

Claims

1. A mechanical extension device for a movable chair, A seat frame for attaching the seat, A backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, It includes a leg extension device pivotally connected to the front of the seat frame, The mechanical extension device is convertible between at least a seated position and a supine position, in the seated position the leg extension device is stored below the seat frame, in the supine position the leg extension device is raised forward and upward and the backrest bracket is tilted backward, and during the conversion process of the mechanical extension device from the seated position to the supine position the rearmost end of the backrest bracket does not have a rearward movement component, in a mechanical extension device for a movable chair, A mechanical extension device for a movable chair, wherein the backrest assembly further includes a first backrest link and a second backrest link, the first backrest link being pivotally connected to the front end of the backrest bracket at a first pivot point and pivotally connected to the seat frame at a second pivot point, and the first pivot point having a motion trajectory toward the leg extension device during the process of converting the mechanical extension device from a seated position to a supine position.

2. A mechanical extension device for a movable chair, A seat frame for attaching the seat, A backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, It includes a leg extension device pivotally connected to the front of the seat frame, The mechanical extension device is convertible between at least a seated position and a supine position, in the seated position the leg extension device is stored below the seat frame, in the supine position the leg extension device is raised forward and upward and the backrest bracket is tilted backward, and during the conversion process of the mechanical extension device from the seated position to the supine position the rearmost end of the backrest bracket does not have a rearward movement component, in a mechanical extension device for a movable chair, A mechanical extension device for a movable chair, characterized in that the backrest assembly further includes a first backrest link and a second backrest link, the second backrest link being configured as a crank member, the crank member including three pivot points which are a third pivot point, a fourth pivot point and a fifth pivot point, the third and fifth pivot points being located at the free ends of the upper and lower arms of the crank member, respectively, the fourth pivot point being located between the third and fifth pivot points, and the second backrest link being pivotally connected to the rear end of the backrest bracket at the third pivot point and pivotally connected to the seat frame at the fourth pivot point.

3. The mechanical extension device according to claim 1 or 2, characterized in that the first backrest link and the seat frame form a first angle with the opening facing the leg extension device, and the first angle is smaller in the supine position than in the seated position.

4. The mechanical extension device according to claim 1 or 2, characterized in that the backrest bracket and the horizontal plane form a second angle with the opening facing the leg extension device, and the second angle is at least 20° larger in the supine position than in the seated position.

5. The mechanical extension device according to claim 1 or 2, wherein the leg extension device includes a footrest for attaching a footrest, and the footrest is raised 300 mm to 400 mm higher in the supine position than in the seated position.

6. The mechanical extension device according to claim 1 or 2, characterized in that the seat frame includes a position regulating portion provided behind the first backrest link, and the position regulating portion is capable of supporting the first backrest link so as to prevent the first backrest link from swaying in the seated position.

7. The mechanical extension device according to claim 1 or 2, wherein the mechanical extension device includes a fixed plate fixedly connected to the armrest portion of a movable chair, the rear portion of the fixed plate is pivotally connected to one end of a fixed plate link, and a second backrest link is further pivotally connected to the other end of the fixed plate link at a fifth pivot point.

8. The mechanical extension device according to claim 7, characterized in that the seat frame is attached to the fixing plate so as to be movable forward and backward by a link mechanism.

9. The mechanical extension device according to claim 8, wherein the link mechanism includes a main link assembly and a sub-link assembly, the main link assembly includes an intermediate link pivotally connected to the sub-link assembly, and during the process of converting the mechanical extension device from a seated position to a supine position, relative displacement occurs between the seat frame and the intermediate link, and between the intermediate link and the fixing plate, in that order.

10. The mechanical extension device according to claim 9, characterized in that the link mechanism includes a seat frame connecting rod, the rear end of the seat frame connecting rod is connected to an intermediate link, and the front end of the seat frame connecting rod is connected to a leg extension device.

11. A mechanical extension device for a movable chair, A seat frame for attaching the seat, A backrest bracket connected to the rear of the seat frame, Includes a leg extension device connected to the front of the seat frame, The mechanical extension device is convertible between a seated position, a TV position, and a supine position, and in the seated position, the leg extension device is stored below the seat frame, in the TV position, the leg extension device is raised forward and upward, and in the supine position, the leg extension device is raised forward and upward, the backrest bracket is tilted backward, and in the process of converting the mechanical extension device from the seated position to the TV position and then to the supine position, the rearmost end of the backrest bracket has a forward movement component, in a mechanical extension device for a movable chair. A mechanical extension device for a movable chair, characterized in that the backrest bracket is connected to the seat frame via a first backrest link and a second backrest link, the upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear of the seat frame at a second pivot point, and during the process of converting the mechanical extension device from a seated position to a supine position, the first pivot point has a motion trajectory in the horizontal direction toward the leg extension device and a motion trajectory in the vertical direction toward downward and then upward.

12. A mechanical extension device for a movable chair, A seat frame for attaching the seat, A backrest bracket connected to the rear of the seat frame, Includes a leg extension device connected to the front of the seat frame, The mechanical extension device is convertible between a seated position, a TV position, and a supine position, and in the seated position, the leg extension device is stored below the seat frame, in the TV position, the leg extension device is raised forward and upward, and in the supine position, the leg extension device is raised forward and upward, the backrest bracket is tilted backward, and in the process of converting the mechanical extension device from the seated position to the TV position and then to the supine position, the rearmost end of the backrest bracket has a forward movement component, in a mechanical extension device for a movable chair. A mechanical extension device for a movable chair, characterized in that the backrest bracket is connected to the seat frame via a first backrest link and a second backrest link, the upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear of the seat frame at a second pivot point, the distance between the first pivot point and the second pivot point is 80 mm to 150 mm, and the first angle formed by the first backrest link and the seat frame, the first angle in which the opening faces the direction of the leg extension device, is less than 90°.

13. The mechanical extension device according to claim 11 or 12, characterized in that the first pivot point is higher in the supine position than in the seated position.

14. The mechanical extension device according to claim 13, characterized in that during the process of changing the mechanical extension device from a seated position to a TV position, the first pivot point moves forward and downward, and during the process of changing the mechanical extension device from a TV position to a supine position, the first pivot point moves forward and upward.

15. The mechanical extension device according to claim 11 or 12, characterized in that the second backrest link is pivotally connected to the rear end of the backrest bracket at a third pivot point and pivotally connected to the rear of the seat frame at a fourth pivot point, the fourth pivot point being located later than the second pivot point.

16. The mechanical extension device according to claim 15, characterized in that the mechanical extension device includes a fixing plate that is fixedly connected to the armrest portion of a movable chair.

17. The mechanical extension device according to claim 16, characterized in that during the process of converting the mechanical extension device from a seated position to a TV position, the rear end of the seat frame is lowered relative to the fixing plate, and during the process of converting the mechanical extension device from a TV position to a supine position, the seat frame is raised relative to the fixing plate.

18. The mechanical extension device according to claim 16, wherein the second backrest link is configured as a crank member and further includes a fifth pivot point, the third and fifth pivot points are located at the free ends of the upper and lower arms of the crank member, respectively, the fourth pivot point is located between the third and fifth pivot points, and the second backrest link is directly or indirectly connected to the fixed plate at the fifth pivot point.

19. The mechanical extension device according to claim 16, wherein the seat frame is attached to the fixed plate so as to be movable forward and backward by a main interlocking assembly and a sub-interlocking assembly, the seat frame is pivotally connected to the main interlocking assembly, and the sub-interlocking assembly is pivotally connected to the fixed plate.

20. The mechanical extension device according to claim 19, wherein the main linkage assembly includes an intermediate link pivotally connected to the sub-linkage assembly, and during the process of converting the mechanical extension device from a seated position to a TV position, the rear end of the seat frame is moved downward and forward relative to the intermediate link by the main linkage assembly, the intermediate link has no relative displacement with respect to the fixed plate, and during the process of converting the mechanical extension device from a TV position to a supine position, the seat frame is moved forward and upward relative to the fixed plate together with the main linkage assembly by the sub-linkage assembly.

21. The mechanical extension device according to claim 1, 2, 11, or 12, characterized in that it is used in a movable chair with floor-standing armrests.

22. The mechanical extension device according to claim 1, 2, 11, or 12, further comprising a linear electric actuator device.

23. A movable chair unit, The armrest section, The backrest and, The seat and, Footrest and A mechanical extension device, including The mechanical extension device is A seat frame for attaching the seat, A backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, It includes a mechanical extension device, which is pivotally connected to the front of the seat frame and includes a leg extension device for attaching a footrest, The chair unit is convertible between at least a seated position and a supine position by the mechanical extension device, in the seated position the footrest is stored below the seat frame, in the supine position the footrest is extended forward and upward and the backrest is tilted backward, and in the process of converting the chair unit from the seated position to the supine position the rearmost end of the backrest does not have a rearward movement component, A movable chair unit characterized in that the backrest assembly further includes a first backrest link and a second backrest link, the first backrest link being pivotally connected to the front end of the backrest bracket at a first pivot point and pivotally connected to the seat frame at a second pivot point, and during the process of converting the mechanical extension device from a seated position to a supine position, the first pivot point has a motion trajectory in the direction of the leg extension device.

24. A movable chair unit, The armrest section, The backrest and, The seat and, Footrest and A mechanical extension device, A seat frame for attaching the seat, A backrest assembly pivotally connected to the rear of the seat frame, the backrest assembly including a backrest bracket for attaching the backrest, It includes a mechanical extension device, which is pivotally connected to the front of the seat frame and includes a leg extension device for attaching a footrest, The chair unit is convertible between at least a seated position and a supine position by the mechanical extension device, in the seated position the footrest is stored below the seat frame, in the supine position the footrest is extended forward and upward and the backrest is tilted backward, and in the process of converting the chair unit from the seated position to the supine position the rearmost end of the backrest does not have a rearward movement component, A movable chair unit characterized in that the backrest assembly further includes a first backrest link and a second backrest link, the second backrest link being configured as a crank member, the crank member including three pivot points which are a third pivot point, a fourth pivot point and a fifth pivot point, the third and fifth pivot points being located at the free ends of the upper and lower arms of the crank member, respectively, the fourth pivot point being located between the third and fifth pivot points, and the second backrest link being pivotally connected to the rear end of the backrest bracket at the third pivot point and pivotally connected to the seat frame at the fourth pivot point.

25. The chair unit according to claim 23 or 24, characterized in that the first backrest link and the seat frame form a first angle with an opening facing the direction of the leg extension device, and the first angle is smaller in the reclining position than in the sitting position.

26. The chair unit according to claim 23 or 24, characterized in that the backrest bracket and the horizontal plane form a second angle with the opening facing the direction of the leg extension device, and the second angle is at least 20° larger in the supine position than in the seated position.

27. The chair unit according to claim 23 or 24, characterized in that the leg extension device includes a footrest for attaching a footrest, and the footrest is raised 300 mm to 400 mm higher in the supine position than in the seated position.

28. The chair unit according to claim 23 or 24, characterized in that the seat frame includes a position regulating portion provided behind the first backrest link, and the position regulating portion is capable of supporting the first backrest link so as to prevent the first backrest link from swaying in the seated position.

29. The chair unit according to claim 23 or 24, characterized in that the mechanical extension device includes a fixed plate fixedly connected to the armrest portion, the rear of the fixed plate pivotally connected to one end of a fixed plate link, and a second backrest link further pivotally connected to the other end of the fixed plate link at a fifth pivot point.

30. The chair unit according to claim 29, characterized in that the seat frame is attached to the fixing plate so as to be movable forward and backward relative to the armrest portion by a link mechanism.

31. The chair unit according to claim 30, wherein the link mechanism includes a main link assembly and a sub-link assembly, the main link assembly includes an intermediate link pivotally connected to the sub-link assembly, and during the process of converting the chair unit from a seated position to a supine position, relative displacement occurs between the seat frame and the intermediate link, and between the intermediate link and the fixing plate, in that order.

32. The chair unit according to claim 31, characterized in that the link mechanism includes a seat frame connecting rod, the rear end of the seat frame connecting rod is connected to an intermediate link, and the front end of the seat frame connecting rod is connected to a leg extension device.

33. A movable chair unit, The armrest section, The backrest and, The seat section and, Footrest and A mechanical extension device, A seat frame for attaching the seat, A backrest bracket for attaching the backrest, It includes a mechanical extension device, which is pivotally connected to the front of the seat frame and includes a leg extension device for attaching a footrest, The chair unit is convertible between a seated position, a TV position, and a supine position by the mechanical extension device, in the seated position the footrest is stored below the seat frame, in the TV position the leg extension device is raised forward and upward, and in the supine position the footrest is raised forward and upward and the backrest is tilted backward, and in the process of the chair unit being converted from the seated position to the TV position and then to the supine position the rearmost end of the backrest has a forward movement component, A movable chair unit characterized in that the backrest bracket is connected to the rear of the seat frame via a first backrest link and a second backrest link, the upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear of the seat frame at a second pivot point, and during the process of converting the chair unit from a seated position to a supine position, the first pivot point has a horizontal motion trajectory toward the leg extension device and a vertical motion trajectory toward downward and then upward.

34. A movable chair unit, The armrest section, The backrest and, The seat section and, Footrest and A mechanical extension device, A seat frame for attaching the seat, A backrest bracket for attaching the backrest, It includes a mechanical extension device, which is pivotally connected to the front of the seat frame and includes a leg extension device for attaching a footrest, The chair unit is convertible between a seated position, a TV position, and a supine position by the mechanical extension device, in the seated position the footrest is stored below the seat frame, in the TV position the leg extension device is raised forward and upward, and in the supine position the footrest is raised forward and upward and the backrest is tilted backward, and in the process of the chair unit being converted from the seated position to the TV position and then to the supine position the rearmost end of the backrest has a forward movement component, A movable chair unit characterized in that the backrest bracket is connected to the rear of the seat frame via a first backrest link and a second backrest link, the upper end of the first backrest link is pivotally connected to the front end of the backrest bracket at a first pivot point, and the lower end of the first backrest link is pivotally connected to the rear of the seat frame at a second pivot point, the distance between the first pivot point and the second pivot point is 80 mm to 150 mm, and the first angle formed by the first backrest link and the seat frame, where the opening faces the direction of the leg extension device, is less than 90°.

35. The chair unit according to claim 33 or 34, characterized in that the first pivot point is higher in the supine position than in the seated position.

36. The chair unit according to claim 33 or 34, characterized in that during the process of changing the chair unit from a seated position to a TV-watching position, the first pivot point moves forward and downward, and during the process of changing the chair unit from a TV-watching position to a supine position, the first pivot point moves forward and upward.

37. The chair unit according to claim 33 or 34, characterized in that the second backrest link is pivotally connected to the rear end of the backrest bracket at a third pivot point and pivotally connected to the rear of the seat frame at a fourth pivot point, the fourth pivot point being located later than the second pivot point.

38. The chair unit according to claim 37, characterized in that the mechanical extension device includes a fixing plate that is fixedly connected to the armrest portion of the movable chair.

39. The chair unit according to claim 38, characterized in that during the process of converting the chair unit from a seated position to a TV-watching position, the rear end of the seat frame is lowered relative to the fixing plate, and during the process of converting the chair unit from a TV-watching position to a supine position, the seat frame is raised relative to the fixing plate.

40. The chair unit according to 38, wherein the second backrest link is configured as a crank member and further includes a fifth pivot point, the third and fifth pivot points are located at the free ends of the upper and lower arms of the crank member, respectively, the fourth pivot point is located between the third and fifth pivot points, and the second backrest link is directly or indirectly connected to the fixing plate at the fifth pivot point.

41. The chair unit according to claim 37, characterized in that the seat frame is attached to a fixed plate so as to be movable forward and backward by a main interlocking assembly and a sub-interlocking assembly, the seat frame is pivotally connected to the main interlocking assembly, and the sub-interlocking assembly is pivotally connected to the fixed plate.

42. The chair unit according to claim 41, wherein the main interlocking assembly includes an intermediate link pivotally connected to the sub-interlocking assembly, and during the process of converting the chair unit from a seated position to a TV position, the rear end of the seat frame is moved downward and forward relative to the intermediate link by the main interlocking assembly, the intermediate link has no relative displacement with respect to the fixed plate, and during the process of converting the chair unit from a TV position to a supine position, the seat frame is moved forward and upward relative to the fixed plate together with the main interlocking assembly by the sub-interlocking assembly.

43. The chair unit according to claim 23, 24, 33, or 34, characterized in that the chair unit is a floor-standing chair unit with armrests.

44. The chair unit according to claim 23, 24, 33, or 34, further comprising a linear electric actuator device.

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