Abstract:
A two-stage adjusting member for adjusting slope of a seat back formed by a first stage adjusting member and a second stage adjusting member is disclosed. A user operates the first stage adjusting member so that the seat back reclines from 90 degrees to 70 degrees to the horizontal. Then the users operates the second stage adjusting member so as to make the seat back further incline backward such as 10 degrees more to another slope. Thus the seat back slope is adjusted in two stages and such design is much more safer for users and can prevent danger or harm caused by suddenly reclining.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to an adjusting member for adjusting seat back slope, especially to a two-stage adjusting member for adjusting seat back slope that the user can operate a first stage adjusting member to make the seat back recline a certain angle. Then by a second stage adjusting member, the seat back further reclines such as 10 degrees more and becomes more close to a horizontal position. Thus the adjustment of the seat back is more safer. 
         [0002]    There are various designs of adjustment mechanisms on office chairs such as height adjustment mechanism for armrests, height adjusting member for seats, seat slope adjusting member, seat back slope adjusting member, height adjusting member for seat backs, or waist support adjusting member, as prior arts disclosed in Taiwanese patent M321261, M326807, M308687, M3281531, M272463, M270739, M244008, M244006, M244008, 1227118, Taiwanese publication No. 00480961, 00312709, 00219466, 00148174, 00051473, 0578518, 00444555, 306219, 296582, Chinese patent No. ZL99235672.5 and U.S. Pat. No. 6,994,400 etc. The seat height adjustment mechanism and/or seat back slope adjustment mechanism are/is disposed in a main frame (first frame) of a base on bottom surface of the seat. Then by a control rod extending from the base to the edge of the bottom surface of the seat and on the left/right sides of the seat, the user can operates the mechanisms by left or right hand according to their needs. 
         [0003]    Now the reclining function of the office chair is getting more important for users, especially for persons who sit on the seat for long period of time such as computer users. The office chair is not only a task chair but also for multiple purposes such as lounge chairs and recliner chairs. Thus the seat back of the office chair requires at least two kinds of slopes for users to choose. Generally, most of the seat back slope adjusting member available now is one-stage adjustment. That means the user adjusts the slope of the seat back only once. While adjusting the chair, the users recline and decide which slope of the seat back they require. However, the base of the office chair is disposed with rolling wheels. Thus the user may recline suddenly a large angle or to an almost flat position, fall backward and get hurts. 
       SUMMARY OF THE INVENTION 
       [0004]    Therefore it is a primary object of the present invention to provide a two-stage adjusting member for adjusting seat back slope that includes a first frame whose top surface is fastened on the bottom surface of the seat, a second frame, a first stage adjusting member and a second stage adjusting member. A bottom surface of the first frame connects with a supporting mount. The rear end of the first frame is pivoted and connected with the second frame. The first stage adjusting member in the two-stage adjusting member for adjusting seat back slope is used to adjust the slope of the seat back to a first stage slope. The front end of the second frame is pivoted and connected with the first frame while the rear end of the second frame is fastened and connected with the seat back. The second stage adjusting member is disposed between the first frame and the second frame. The user operates the first stage adjusting member so as to make the seat back recline an angle for users to lie face up. Furthermore, the user operates the second stage adjusting member so that the seat back reclines from the first stage slope to the second stage slope. Thus the two-stage adjustment of the seat back is much more safer for users. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  is an embodiment of the present invention assembled on an office chair; 
           [0006]      FIG. 2  is a perspective view of an embodiment according to the present invention; 
           [0007]      FIG. 3  is a partial enlarged view of the embodiment in  FIG. 2 ; 
           [0008]      FIG. 4  is an explosive view of an embodiment according to the present invention; 
           [0009]      FIG. 5  is an explosive view of a seat back depth adjusting member of an embodiment according to the present invention; 
           [0010]      FIG. 6  is a schematic drawing showing a usage of an embodiment according to present invention; 
           [0011]      FIG. 7  shows an embodiment of the present invention recline to a first stage slope; 
           [0012]      FIG. 8  shows an embodiment of the present invention recline to a second stage slope; 
           [0013]      FIG. 9  shows a user lying face up in the embodiment in  FIG. 8 ; 
           [0014]      FIG. 10  shows a status before adjustment of an embodiment according to the present invention; 
           [0015]      FIG. 11  shows a status after adjustment of the embodiment in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0016]    Refer from  FIG. 1  to  FIG. 4 , a two-stage adjusting member for adjusting seat back slope  1  according to the present invention includes a first frame  20 , a second frame  30  and a second stage adjusting member  40 . The two-stage adjusting member for adjusting seat back slope  1  is disposed on a bottom surface  11  of a seat  10  and a rear end thereof extends to and fastened with a seat back  13  so that a certain angle formed between the seat  10  and the seat back  13 , as shown in  FIG. 6 . 
         [0017]    A top surface of the first frame  20  is fastened on the bottom surface  11  of the seat  10  while a bottom surface of the first frame  20  connects with a supporting mount  12  standing on the ground. By a pivot  50 , the first frame  20  is pivoted with the second frame  30 . A first stage adjusting member  21  is disposed on the first frame  20  and the second frame  30  is pivoted backward to a certain angle (about 20 degrees) around the pivot  50  by operation of a first adjustment rod  211 . Thus the seat back  13  on top of the second frame  30  also reclines an angle A, as shown in  FIG. 7 . This is the first stage adjustment. 
         [0018]    A front end of the second frame  30  is pivoted and connected with the first frame  20  by the pivot  50  while a rear end of the second frame  30  is fastened with the seat back  13 . Refer from  FIG. 6  to  FIG. 10 , an elastic device  14  is formed by a spring and is used to adjust supporting strength of the seat back  13  while the seat back reclining. That&#39;s elastic returning strength of the seat back  13  that enables the seat back  13  to turn back. Moreover, a seat back depth adjusting member  60  is disposed on the second frame  30 . The seat back depth adjusting member  60  makes the seat back  13  move from an anterior position, as shown in  FIG. 10 , to a rearward position, as shown in  FIG. 11 . In this embodiment, the seat back depth adjusting member  60  is formed by an upper housing and a lower housing ( 60 ). A top surface  61  thereof is disposed with two vertical serrated slots  62  and stopping surfaces  63 , as shown in  FIG. 4  &amp;  FIG. 5 . The seat back depth adjusting member  60  corresponds to a stage control device  64 . The stage control device  64  includes an adjusting rod  65  that inserts through and locates between two holes  33  of the second frame  30 . Two sets of positioning rings  66  and cams  67  are arranged on the adjusting rod  65 , respectively and symmetrically on the right and left sides. That means each one side of the adjusting rod  65  is disposed with one positioning ring  66  and one cam  67 . Through an insertion hole  34  on the second frame  30 , the positioning ring  66  and one cam  67  correspond to and work with the serrated slots  62  and the stopping surface  63 . When the positioning ring  66  and one cam  67  are respectively released from the serrated slot  62  and the stopping surface  63 , the seat back  13  is able to be adjusted forward or backward for changing depth. After moving to a certain depth, rotate the adjusting rod  65  so that the two sets of positioning rings  66  and cams  67  rotate synchronously and the positioning ring  66  locks into one of the serrated slots  62  while the cam  67  presses against on the stopping surface  63  so as to finish operation of the seat back depth adjusting member  60 . Thus the space for seating or reclining of the seat is adjusted for improving comfort of the chair. Furthermore, a fixing member  68  is further disposed between the upper and the lower housing ( 60 ), as shown in  FIG. 5 . Thus the fastening strength of the seat back depth adjusting member  60  with the seat back  13  is improved. 
         [0019]    Refer to  FIG. 4 , the second stage adjusting member  40  is arranged between the first frame  20  and the second frame  30 . As shown in  FIG. 7 , when the seat back  13  reclines a certain angle A by the adjustment of the first stage adjusting member  21 , the seat back  13  can recline a further angle B such as 10 degrees, as shown in  FIG. 8 . Thus the user can lie face up and take a good rest, as shown in  FIG. 9 . The second stage adjusting member  40  includes a pin  41  formed by an inner end  411  and an outer end  412  and being disposed between left and right holes  23  of the first frame  20 . The second frame  30  includes left and right holes  31   a - 31   b  corresponding to the left and right holes  23  of the first frame  20 . 
         [0020]    Moreover, the inner end  411  of the pin  41  connects to a handle  42  while the handle  42  is connected with a guide pin  46  which is disposed in a guiding hole  32  of the second frame  30  moveably. The pin  41  is arranged with an elastic member  43  such as spring and is restricted by a stopping block  44  so that the pin  41  can turn back automatically by elasticity of the elastic member  43  after movement. Furthermore, a projective rod  45  on the pin  41  moves freely inside the hole  31   a  of the second frame  30 . Thereby, when the handle  42  is pulled outward horizontally by guiding of the guide pin  46 , the outer end  412  of the pin  41  and the projective rod  45  synchronously move outward and release from the hole  31   b  and the hole  31   a  of the second frame  30  respectively. Now the second frame  30  further reclines an angle such as ten degrees from the slope of the first stage so that the slope of the second stage is achieved. In comparison, the conventional adjusting member only has one stage adjustment and the chair may recline from a vertical position to almost a flat position suddenly. This may cause danger or harm to users. Instead, the present invention adjusts the slope of the seat back  13  in two stages. By two-stage adjustment, the chair becomes much more safer. In addition, the second-stage slope can automatically turn back by elasticity of the spring of the elastic member  14 , as shown from  FIG. 6  to  FIG. 10 . Thus it&#39;s convenient for users to adjust the slope of the chair from the second stage back to the first stage. And the pin  41  also turns back to the original position-into the holes  31   b ,  31   a  automatically by the elasticity of the elastic member  43 . 
         [0021]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, and representative devices shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.