Patent Publication Number: US-10306988-B2

Title: Moon chair

Description:
The present application claims the benefit of priority to Chinese patent application No. 201520194228.9 titled “MOON CHAIR”, filed with the Chinese State Intellectual Property Office on Apr. 1, 2015, the entire disclosure of which is incorporated herein by reference. 
     FIELD 
     The present application relates to the technical field of seats, in particular to a moon chair. 
     BACKGROUND 
     A moon chair is a leisure chair frequently used in the daily home life, and includes a chair frame and fabric. The fabric is fixed on the frame, and after a person seats on the fabric, the chair looks like a crescent when looking from one side, thus the chair is named as a moon chair. The chair frame of the moon chair includes a seat rod, a front foot rod and a rear foot rod. The front foot rod and the rear foot rod are used to support the seat rod and ensure the stability and height of the moon chair when it is unfolded. 
     In the conventional technology, the front foot rod and the rear foot rod of the moon chair are generally arranged crosswise and upper ends thereof are both fixed on the seat rod. When the chair is unfolded or folded, the front foot rod and the rear foot rod crosswise slide with respect to each other. In some moon chairs, the foot rods are further provided with hanger positioning elements, and an opening angle between the front foot rod and the rear foot rod can be chosen by coupling grooves of the hangers with the hanger positioning elements of the foot rod, to allow the seat rod of the moon chair to be arranged at different inclination angles and heights. However, for the moon chair with the above structure, it is required to position the hangers when the moon chair is to be unfolded and to press the hangers to unlock the hangers when the moon chair is to be folded, and the tubes are dispersed and not fixed after the moon chair is folded, therefore it is inconvenient to use the moon chair and the operation is complicated. 
     SUMMARY 
     For addressing the issue that the moon chair of a crossed structure in the conventional technology is inconvenient to use, a new moon chair is provided according to the present application. 
     The moon chair according to the present application includes a seat rod, a front foot rod and a rear foot rod, and the front foot rod and the rear foot rod are respectively articulated to the seat rod. The moon chair further includes a first supporting rod, a second supporting rod and a fixing member. The first supporting rod is respectively articulated to the seat rod and the fixing member. The second supporting rod is respectively articulated to the front foot rod and the fixing member. The fixing member is installed on the rear foot rod. The fixing member has a first working state and a second working state. In the case that the fixing member is in the first working state, the moon chair is in an unfolded state; and in the case that the fixing member is in the second working state, the moon chair is in a folded state. 
     The first supporting rod is connected to the seat rod and the fixing member on the rear foot rod, to form a stable triangular supporting structure. The second supporting rod is connected to the front foot rod and the fixing member on the rear foot rod, to form a stable triangular supporting structure. The moon chair can be unfolded or folded by switching the fixing member between the first working state and the second working state, which is very convenient. After the moon chair is folded, the fixing member is in the second working state, which ensures the stability of the folding state. 
     Preferably, the fixing member is a rotatable fixing member. The rotatable fixing member has one end articulated to the rear foot rod and another end articulated to the first supporting rod and the second supporting rod. One side of the rotatable fixing member is provided with a clamping groove. In the case that the rotatable fixing member is in the first working state and the moon chair is in the unfolded state, the clamping groove is configured to clamp the rear foot rod; and in the case that the rotatable fixing member is in the second working state and the moon chair is in the folded condition, the clamping groove is configured to clamp the seat rod. 
     With the rotatable fixing member, in the first working state, the first supporting rod is subjected to a force to allow the rotatable fixing member to tightly clamp the rear foot rod, and the second supporting rod ensures an opening angle between the front foot rod and the rear foot rod to keep constant, thereby ensuring the stability of the moon chair in the unfolded state. When it is required to fold the moon chair, the rotatable fixing member can be switched to the second working state from the first working state by pushing the second supporting rod, to allow the clamping groove to clamp the seat rod, therefore it is very convenient to fold the moon chair. 
     The rotatable fixing member is articulated to the rear foot rod by a first articulated shaft. The rotatable fixing member is articulated to the first supporting rod by a second articulated shaft. The first supporting rod is articulated to the seat rod by a third articulated shaft. The second articulated shaft is located in a connecting line connecting the first articulated shaft and the third articulated shaft at a side close to the front foot rod, or the second articulated shaft is located in the connecting line. 
     Since the second articulated shaft is located in the connecting line connecting the first articulated shaft and the third articulated shaft at a side close to the front foot rod, or the second articulated shaft is located in the connecting line, the pressure may be transferred from the first supporting rod to the rotatable fixing member, to allow the rotatable fixing member to tightly press against the rear foot rod. 
     Preferably, the fixing member is a rotatable fixing member; the rotatable fixing member has a first end articulated to the rear foot rod by a first articulated shaft and a second end articulated to the first supporting rod and the second supporting rod via a drum-shaped stopper. In the case that the rotatable fixing member is in the first working state and the moon chair is in the unfolded state, the drum-shaped stopper is configured to abut against the rear foot rod at a first position higher than the first articulated shaft; and in the case that the rotatable fixing member is in the second working state and the moon chair is in the folded condition, the drum-shaped stopper is configured to abut against the rear foot rod at a second position lower than the first articulated shaft. 
     Further, the drum-shaped stopper has a drum-shaped portion and a rod portion, the rod portion of the drum-shaped stopper is configured to pass through respective through holes in the second end of the rotatable fixing member, the first supporting rod and the second supporting rod, to allow the first supporting rod and the second supporting rod to be articulated to the rotatable fixing member; and the drum-shaped portion has a necked portion which is necked in the radial direction of the drum-shaped stopper and configured to cooperate with an outer surface of the rear foot rod. 
     Further, the first supporting rod is articulated to the seat rod by a second articulated shaft; and the drum-shaped stopper, by which the rotatable fixing member is articulated to the first supporting rod, is located in a connecting line connecting the first articulated shaft and the second articulated shaft at a side close to the front foot rod, or the drum-shaped stopper is located in the connecting line. 
     Further, a first seat-rod supporting tube and a second seat-rod supporting tube respectively configured to connect the front foot rod and the rear foot rod are symmetrically fixed below the seat rod at two sides of the seat rod, two ends of the first seat-rod supporting tube at a left side of the seat rod are fixed to the seat rod; and two ends of the second seat-rod supporting tube at a right side of the seat rod are fixed to the seat rod; the front foot rod is articulated to each of the first seat-rod supporting tube and the second seat-rod supporting tube at an inner side of the respective seat-rod supporting tube, and a first spacer is arranged between articulated ends of the front foot rod and the respective seat-rod supporting tube; the rear foot rod is articulated to each of the first seat-rod supporting tube and the second seat-rod supporting tube at an outer side of the respective seat-rod supporting tube, and a second spacer is arranged between articulated ends of the rear foot rod and the respective seat-rod supporting tube; and a third spacer is arranged between articulated ends of the first supporting rod and the second supporting rod. 
     The fixing member is a slidable fixing member. The slidable fixing member includes a main body and a pin. The main body is sleeved on the rear foot rod. The rear foot rod has a first fixing position and a second fixing position for fixing the slidable fixing member; and the main body is configured to be fixed at the first fixing position or the second fixing position by the pin. 
     In the case that the slidable fixing member is in the first working state and the moon chair is in the unfolded state, the main body is configured to be fixed at the first fixing position by the pin; and in the case that the slidable fixing member is in the second working state and the moon chair is in the folded condition, the main body is configured to be fixed at the second fixing position by the pin. 
     Preferably, the pin is a spring pin. 
     Preferably, the rear foot rod is provided with a plurality of the first fixing positions. 
     By using the pin to fix the slidable fixing member, the position of the moon chair is fixed by the pin when it is unfolded or folded, therefore the structure is stable and the operation is very convenient. 
     Preferably, the seat rod includes a first seat rod, a second seat rod and a seat rod reinforcement tube, and the first seat rod and the second seat rod are connected by the seat rod reinforcement tube. 
     The seat rod includes a foot rod connection strap, and the foot rod connection strap is articulated to the front foot rod and/or the rear foot rod. 
     Preferably, a bottom of the front foot rod and a bottom of the rear foot rod are each further provided with a foot sleeve. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic view showing a moon chair according to a first embodiment of the present application when the moon chair is unfolded; 
         FIG. 2  is a schematic view showing the moon chair according to the first embodiment of the present application when the moon chair is partially folded; 
         FIG. 3  is a schematic view showing the moon chair according to the first embodiment of the present application when the moon chair is completely folded; 
         FIG. 4  is a schematic view showing a moon chair according to a second embodiment of the present application when the moon chair is unfolded; 
         FIG. 5  is a schematic view showing the moon chair according to the second embodiment of the present application when the moon chair is partially folded; 
         FIG. 6  is a schematic view showing the moon chair according to the second embodiment of the present application when the moon chair is completely folded; and 
         FIG. 7  is a schematic view showing a moon chair according to a third embodiment of the present application when the moon chair is unfolded. 
       
         
           
             
                 
               
                 
                     
                 
               
              
                 
                   Reference Numerals in FIGS. 1 to 3: 
                 
              
             
             
                 
                 
                 
                 
              
                 
                   11 
                   seat rod, 
                   111 
                   first seat rod, 
                 
                 
                   112 
                   second seat rod, 
                   113 
                   seat rod reinforcement tube, 
                 
                 
                   12 
                   front foot rod, 
                   13 
                   rear foot rod, 
                 
                 
                   14 
                   first supporting rod, 
                   15 
                   second supporting rod, 
                 
                 
                   16 
                   rotatable fixing member, 
                   17 
                   foot rod connection strap, 
                 
                 
                   18 
                   foot sleeve, 
                   101 
                   first articulated shaft, 
                 
                 
                   102 
                   second articulated shaft, 
                   103 
                   third articulated shaft. 
                 
              
             
             
                 
              
                 
                   Reference Numerals in FIGS. 4 to 6: 
                 
              
             
             
                 
                 
                 
                 
              
                 
                   31 
                   seat rod, 
                   311 
                   first seat-rod supporting tube, 
                 
                 
                   312 
                   second seat-rod supporting 
                   32 
                   front foot rod, 
                 
                 
                     
                   tube, 
                 
                 
                   33 
                   rear foot rod, 
                   34 
                   first supporting rod, 
                 
                 
                   35 
                   second supporting rod, 
                   36 
                   rotatable fixing member, 
                 
                 
                   37 
                   drum-shaped stopper, 
                   38 
                   foot sleeve, 
                 
                 
                   39 
                   spacer, 
                   301 
                   first articulated shaft, 
                 
                 
                   302 
                   second articulated shaft. 
                 
              
             
             
                 
              
                 
                   Reference Numerals in FIG. 7: 
                 
              
             
             
                 
                 
                 
                 
              
                 
                   21 
                   seat rod, 
                   211 
                   first seat rod, 
                 
                 
                   212 
                   second seat rod, 
                   213 
                   seat rod reinforcement tube, 
                 
                 
                   22 
                   front foot rod, 
                   23 
                   rear foot rod, 
                 
                 
                   24 
                   first supporting rod, 
                   25 
                   second supporting rod, 
                 
                 
                   26 
                   slidable fixing member, 
                   27 
                   foot rod connection strap, 
                 
                 
                   28 
                   foot sleeve. 
                 
                 
                     
                 
              
             
           
         
       
     
    
    
     DETAILED DESCRIPTION 
     For those skilled in the art to better understand technical solutions of the present application, the present application is further described in detail below in conjunction with drawings and embodiments. 
     First Embodiment 
       FIGS. 1 to 3  are schematic views respectively showing that a moon chair according to the first embodiment of the present application when the moon chair is unfolded, partially folded and completely folded. As shown in  FIGS. 1 and 2 , the moon chair according to the first embodiment includes a seat rod  11 , a front foot rod  12 , a rear foot rod  13 , a first supporting rod  14 , a second supporting rod  15  and a rotatable fixing member  16 . The front foot rod  12  and the rear foot rod  13  are each articulated to the seat rod  11 , a side of the rotatable fixing member  16  is provided with a clamping groove configured to clamp the rear foot rod  13  or the seat rod  11 . The rotatable fixing member  16  has one end articulated to the rear foot rod  13  and is rotatable around a first articulated shaft  101  which is connected to the rear foot rod  13 . Two ends of the first supporting rod  14  are respectively articulated to the seat rod  11  and the rotatable fixing member  16 , and two ends of the second supporting rod  15  are respectively articulated to the front foot rod  12  and the rotatable fixing member  16 . The rotatable fixing member  16  has two working states, including a first working state and a second working state. In the first working state, the rotatable fixing member  16  is rotated clockwise around the first articulated shaft  101  to allow the clamping groove to clamp the rear foot rod  13 . In the second working state, the rotatable fixing member  16  is rotated anticlockwise around the first articulated shaft  101  to allow the clamping groove to clamp the seat rod  11 . 
     In the case that the moon chair is unfolded, that is, the rotatable fixing member  16  is in the first working state, when a pressure is exerted on the seat rod  11  in a vertical direction, the front foot rod  12  tends to rotate forward (i.e. the anticlockwise direction in  FIG. 1 ) and drives the second supporting rod  15  to move forward, thus driving the rotatable fixing member  16  to tightly clamp the rear foot rod  13 . The second supporting rod  15  can ensure an opening angle between the front foot rod  12  and the rear foot rod  13  to reach a maximum value. 
     As shown in  FIG. 1 , when the rotatable fixing member  16  is in the first working state, the first articulated shaft  101  by which the rear foot rod  13  and the rotatable fixing member  16  are connected, a second articulated shaft  102  by which the rotatable fixing member  16  and the first supporting rod  14  are connected, and a third articulated shaft  103  by which the first supporting rod  14  and the seat rod  11  are connected are not in a straight line, and the second articulated shaft  102  is at a position close to the front foot rod  12 , therefore the second articulated shaft  102  passes beyond a dead center of the crank structure. When a pressure is exerted on the seat rod  11 , the pressure is transferred to the rotatable fixing member  16  by the first supporting rod  14 , thus the rotatable fixing member  16  is tightly pressed against the rear foot rod  13 . 
     Therefore, the stability of the whole moon chair in an unfolded state (as shown in  FIG. 1 ) can be ensured by the combined action of the first supporting rod  14  and the second supporting rod  15 . Of course, in other embodiments, the second articulated shaft  102  may also be in a line connecting the first articulated shaft  101  and the third articulated shaft  103 . For example, when a person is seated on the moon chair, if a transverse force exerted on the rotatable fixing member  16  by the second supporting rod  15  is greater than a transverse force exerted on the rotatable fixing member  16  by the first supporting rod  14 , the second articulated shaft  102  may also be in the line connecting the first articulated shaft  101  and the third articulated shaft  103  at a side away from the front foot rod  12 . 
     When it is required to fold the moon chair, the rotatable fixing member  16  rotates around the first articulated shaft  101  anticlockwise to reach a position shown in  FIG. 2 . When the rotatable fixing member  16  continues to rotate, the rotatable fixing member  16  reaches the second working state, and the clamping groove clamps the seat rod  11 . In this case, the moon chair has been folded and reaches the position shown in  FIG. 3 . In conclusion, during a process of folding the moon chair, an external force is exerted on the front foot rod  12  towards the rear foot rod  13 , to drive the rotatable fixing member  16  to leave the first working state and rotate around the first articulated shaft  101  to finish the folding operation, and thus the operation is very convenient. 
     In this embodiment of the present application, the seat rod  11 , the front foot rod  12 , the rear foot rod  13 , the first supporting rod  14  and the second supporting rod  15  are all circular hollow tubes, which can decrease the weight of the whole moon chair and decrease edges and corners on the whole moon chair to avoid collision injuries. Of course, in other embodiments, the above parts may also be made of solid tubes and the rods may also have various cross-sectional shapes. 
     In this embodiment of the present application, the first supporting rod  14  and the second supporting rod  15  are articulated to the rotatable fixing member  16  by the same articulated shaft that is the second articulated shaft  102 . By using the same articulated shaft, the number of holes perforated on the rotatable fixing member  16  may be reduced, the strength of the rotatable fixing member  16  is improved and the structure of the rotatable fixing member  16  is simplified. 
     The seat rod  11  of the moon chair according to the embodiment of the present application may include a first seat rod  111 , a second seat rod  112  and a seat rod reinforcement tube  113 , and the seat rod reinforcement tube  113  is used to connect the first seat rod  111  to the second seat rod  112 . It can be understood that, the seat rod  11  can be formed by one rod element, or formed by several rod elements connected by welding, clamping or sleeving. The front foot rod  12 , the rear foot rod  13  and the first supporting rod  14  are all articulated to the seat rod reinforcement tube  113 , to be connected to the seat rod  11 . Of course, the front foot rod  12 , the rear foot rod  13  and the first supporting rod  14  may also be connected to the first seat rod  111 , the second seat rod  112  and the seat rod reinforcement tube  113 , respectively. The seat rod  11  of the moon chair in the embodiment of the present application is of a rectangular shape, and may also have other shapes in other embodiments, such as a circular shape or other personalized shapes. 
     In this embodiment, the seat rod  11  is provided with a foot rod connection strap  17 . The foot rod connection strap  17  is fixed on the seat rod reinforcement tube  113 , and the rear foot rod  13  is articulated to the foot rod connection strap  17 , to be connected to the seat rod  11 . Therefore, in this case, when the rear foot rod  13  rotates, the plane of the rotation of two lateral rods connected to the seat rod  11  is coplanar with two lateral rods of the seat rod  11 . The front foot rod  12  is arranged at an inner side of the seat rod  11 , the first supporting rod  14  is arranged at an inner side of the seat rod  11  and an inner side of the rotatable fixing member  16 , and the second supporting rod  15  is arranged at an inner side of the first supporting rod  14  and an inner side of the front foot rod  12 . Therefore, during the process of folding the moon chair, the first supporting rod  14 , the second supporting rod  15 , the front foot rod  12  and the rear foot rod  13  will not interfere with each other, and after the moon chair is folded, the front foot rod  12 , the first supporting rod  14  and the second supporting rod  15  are all located at the inner side of the seat rod  11  and the inner side of the rear foot rod  13 . Of course, other stacked structures can also be used to connect the parts of the moon chair according to this embodiment, to facilitate folding the moon chair. 
     For forming a stable supporting plane on the ground, the bottoms of the front foot rod  12  and the rear foot rod  13  are each further provided with a foot sleeve  18  in this embodiment. Of course, in other embodiments, the front foot rod  12  and the rear foot rod  13  may directly touch the ground without the foot sleeve  18 . 
     Second Embodiment 
       FIGS. 4 to 6  are schematic views respectively showing that a moon chair according to the second embodiment of the present application when the moon chair is unfolded, partially folded and completely folded. As shown in  FIGS. 4 and 5 , the moon chair according to the second embodiment includes a seat rod  31 , a front foot rod  32 , a rear foot rod  33 , a first supporting rod  34 , a second supporting rod  35  and a rotatable fixing member  36 . The front foot rod  32  and the rear foot rod  33  are each articulated to the seat rod  31 , the rotatable fixing member  36  has a first end articulated to the rear foot rod  33  and is rotatable around a first articulated shaft  301  which is connected to the rear foot rod  33 , and has a second end provided with a drum-shaped stopper  37  configured to abut against the rear foot rod  33 . Two ends of the first supporting rod  34  are respectively articulated to the seat rod  31  and the rotatable fixing member  36 , and two ends of the second supporting rod  35  are respectively articulated to the front foot rod  32  and the rotatable fixing member  36 . The rotatable fixing member  36  has two working states, including a first working state and a second working state. In the first working state, the rotatable fixing member  36  is rotated clockwise around the first articulated shaft  301  to allow the drum-shaped stopper  37  to abut against the rear foot rod  33  at a first position higher than the first articulated shaft  301 . In the second working state, the rotatable fixing member  36  is rotated anticlockwise around the first articulated shaft  301  to allow the drum-shaped stopper  37  to abut against the rear foot rod  33  at a second position lower than the first articulated shaft  301 . 
     As shown in  FIGS. 4 to 6 , the rotatable fixing member  36  is embodied as an elongated plate, and the first end of the rotatable fixing member  36  is articulated to the rear foot rod  33  at the inner side of the rear foot rod  33  via the first articulated shaft  301 . The second end of the rotatable fixing member  36  is provided with a first through hole, the end of the first supporting rod  34  that is articulated to the rotatable fixing member  36  is provided with a second through hole, the end of the second supporting rod  35  that is articulated to the rotatable fixing member  36  is also provided with a third through hole. The drum-shaped stopper  37  has a drum-shaped portion and a rod portion, and the rod portion of the drum-shaped stopper  37  passes through the first through hole, the second through hole and the third through hole, and the rotatable fixing member  36 , the first supporting rod  34  and the second supporting rod  35  are rotatable around the drum-shaped stopper  37 , thus the first supporting rod  34  and the second supporting rod  35  are each articulated to the rotatable fixing member  36  via the drum-shaped stopper  37 . The drum-shaped portion of the drum-shaped stopper  37  has a necked portion which is necked in the radial direction of the drum-shaped stopper  37 , and when the drum-shaped stopper  37  is pressed against the rear foot rod  33 , the necked portion cooperates with the outer surface of the rear foot rod  33  to limit the movement of the rear foot rod  33 . 
     In the case that the moon chair is unfolded, that is, the rotatable fixing member  36  is in the first working state, when a pressure is exerted on the seat rod  31  in a vertical direction, the front foot rod  32  tends to rotate forward (i.e. the anticlockwise direction in  FIG. 4 ) and drives the second supporting rod  35  to move forward, thus driving the drum-shaped stopper  37  at the second end of the rotatable fixing member  36  to tightly abut against the rear foot rod  33  at the first position. The second supporting rod  35  can ensure an opening angle between the front foot rod  32  and the rear foot rod  33  to reach a maximum value. 
     As shown in  FIG. 4 , when the rotatable fixing member  36  is in the first working state, the first articulated shaft  301  by which the rear foot rod  33  and the rotatable fixing member  36  are connected, the drum-shaped stopper  37  by which the rotatable fixing member  36  and the first supporting rod  34  are connected, and a second articulated shaft  302  by which the first supporting rod  34  and the seat rod  31  are connected are not in a straight line, and the drum-shaped stopper  37  is at a position close to the front foot rod  32 , therefore the drum-shaped stopper  37  passes beyond a dead center of the crank structure. When a pressure is exerted on the seat rod  31 , the pressure is transferred to the drum-shaped stopper  37  by the first supporting rod  34 , thus the drum-shaped stopper  37  at the second end of the rotatable fixing member  36  is tightly pressed against the rear foot rod  33 . 
     Therefore, the stability of the whole moon chair in an unfolded state (as shown in  FIG. 4 ) can be ensured by the combined action of the first supporting rod  34  and the second supporting rod  35 . Of course, in other embodiments, the drum-shaped stopper  37  may also be in a line connecting the first articulated shaft  301  and the second articulated shaft  302 . For example, when a person is seated on the moon chair, if a transverse force exerted on the drum-shaped stopper  37  by the second supporting rod  35  is greater than a transverse force exerted on the drum-shaped stopper  37  by the first supporting rod  34 , the drum-shaped stopper  37  may also be in the line connecting the first articulated shaft  301  and the second articulated shaft  302  at a side away from the front foot rod  32 . 
     When it is required to fold the moon chair, the rotatable fixing member  36  rotates around the first articulated shaft  301  anticlockwise to reach a position shown in  FIG. 5 . When the rotatable fixing member  36  continues to rotate, the rotatable fixing member  36  reaches the second working state, and the drum-shaped stopper  37  at the second end of the rotatable fixing member  36  abuts against the rear foot rod  33  at the second position. In this case, the moon chair has been folded and reaches the position shown in  FIG. 6 . In conclusion, during a process of folding the moon chair, an external force is exerted on the front foot rod  32  towards the rear foot rod  33 , to drive the rotatable fixing member  36  to leave the first working state and rotate around the first articulated shaft  301  to finish the folding operation, and thus the operation is very convenient. 
     In this embodiment of the present application, the seat rod  31 , the front foot rod  32 , the rear foot rod  33 , the first supporting rod  34  and the second supporting rod  35  are all circular hollow tubes, which can decrease the weight of the whole moon chair and decrease edges and corners on the whole moon chair to avoid collision injuries. Of course, in other embodiments, the above parts may also be made of solid tubes and the rods may also have various cross-sectional shapes. 
     In this embodiment of the present application, the first supporting rod  34  and the second supporting rod  35  are articulated to the rotatable fixing member  36  by the same member that is the drum-shaped stopper  37 . By using the same member, the number of holes perforated on the rotatable fixing member  36  may be reduced, the strength of the rotatable fixing member  36  is improved and the structure of the rotatable fixing member  36  is simplified. 
     The seat rod  31  of the moon chair according to the embodiments of the present application may have various shapes, for example the rectangular shape shown in  FIGS. 1 to 3 and 7 , or the circular shape shown in  FIGS. 4 to 6 , and the shape of the seat rod  31  is not limited to the above described shapes. 
     The seat rod  31  is described hereinafter by taking the circular shape in  FIGS. 4 to 6  as an example, a first seat-rod supporting tube  311  and a second seat-rod supporting tube  312  are symmetrically fixed below the circular seat rod  31  at two sides of the circular seat rod  31 . Two ends of the first seat-rod supporting tube  311  at the left side of the circular seat rod  31  are fixed to the circular seat rod  31 , by screws or bolts; and two ends of the second seat-rod supporting tube  312  at the right side of the circular seat rod  31  are fixed to the circular seat rod  31 , by screws or bolts. The first seat-rod supporting tube  311  and the second seat-rod supporting tube  312  are configured to connect the front foot rod  32  and the rear foot rod  33 . 
     The connection relationship between the front foot rod  32 , the rear foot rod  33  and the first and second seat-rod supporting tubes  311  and  312  is described by taking the first seat-rod supporting tube  311  at the left side as an example. The front foot rod  32  is articulated to the first seat-rod supporting tube  311  at the inner side of the first seat-rod supporting tube  311 , and a spacer  39  is arranged between the articulated ends of the front foot rod  32  and the first seat-rod supporting tube  311 ; and the rear foot rod  33  is articulated to the first seat-rod supporting tube  311  at the outer side of the first seat-rod supporting tube  311 , and a spacer  39  is also arranged between the articulated ends of the rear foot rod  33  and the first seat-rod supporting tube  311 . In addition, a spacer  39  may be further arranged between the articulated ends of the first supporting rod  34  and the second supporting rod  35 , that is, the rod portion of the drum-shaped stopper  37  also passes though the spacer  39 . With the arrangement of the spacers  39 , during the process of folding the moon chair, the first supporting rod  34 , the second supporting rod  35 , the front foot rod  32 , the rear foot rod  33  and the first seat-rod supporting tube  311  will not interfere with each other. And when the moon chair is folded, as shown in  FIG. 6 , the rear foot rod  33 , the first seat-rod supporting tube  311  and the front foot rod  32  are in parallel with each other, thus the thickness of the folded moon chair is further reduced, and the moon chair according to this embodiment has a small package size, which also reduces the package cost. 
     For forming a stable supporting plane on the ground, the bottoms of the front foot rod  32  and the rear foot rod  33  are each further provided with a foot sleeve  38  in this embodiment. Of course, in other embodiments, the front foot rod  32  and the rear foot rod  33  may directly touch the ground without the foot sleeve  38 . 
     Third Embodiment 
       FIG. 7  is a schematic view showing a moon chair according to a third embodiment of the present application when the moon chair is unfolded. As shown in  FIG. 7 , the whole structure of the moon chair presenting this embodiment is similar to the structure of the moon chair in the first embodiment, and the differences between the two embodiments are described in detail below. 
     The moon chair in this embodiment employs a slidable fixing member  26 . The slidable fixing member  26  includes a pin and a main body sleeved on a rear foot rod  23 . The main body is provided with a through hole, the rear foot rod  23  includes a first fixing position and a second fixing position, and the rear foot rod  23  is provided with through holes respectively at the first fixing position and the second fixing position. In a first working state, the pin passes through the through hole in the main body and the through hole at the first fixing position of the rear foot rod  23 , to fix the slidable fixing member  26  at the first fixing position, and in a second working state, the pin passes through the through hole in the main body and the through hole at the second fixing position of the rear foot rod  23 , to fix the slidable fixing member  26  at the second fixing position. When the pin is at the first fixing position, the moon chair is unfolded. When the pin is in the second fixing position, the moon chair is folded. It can be understood that, in this embodiment, the rear foot rod  23  may be provided with multiple first fixing positions, to provide various choices for the opening height of the moon chair and the opening angle between a front foot rod  22  and the rear foot rod  23 , to adapt to various application environments. It should be noted that, since this embodiment employs the pin to fix the slidable fixing member  26 , there is no need to consider the dead center. 
     In this embodiment, the pin may be a spring pin. A pin shaft of the spring pin may be pulled outwards to allow the slidable fixing member  26  to be switched between the first working state and the second working state, and after the switching of the working states is realized, the pin shaft of the spring pin can automatically retract into the through hole in the respective fixing position. Of course, ordinary pins may also be used in other embodiments. 
     By using the slidable fixing member  26 , a first supporting rod  24  and a second supporting rod  25  are respectively arranged at two sides of the slidable fixing member  26  and the rear foot rod  23 , thus two sides of the main body of the slidable fixing member  26  in this embodiment are respectively provided with articulated shafts respectively connected to the first supporting rod  24  and the second supporting rod  25 . Furthermore, unlike the first embodiment, a foot rod connection strap  27  employed in this embodiment is articulated to both the front foot rod  22  and the rear foot rod  23 . 
     The moon chair according to the embodiments of the present application is described in detail hereinbefore. The principle and the embodiments of the present application are illustrated herein by specific examples. The above description of examples is only intended to help the understanding of the technical solution of the present application. It should be noted that, for the person skilled in the art, a few of modifications and improvements may be made to the present application without departing from the principle of the present application, and these modifications and improvements are also deemed to fall into the scope of the present application defined by the claims.