| 主权项 |
1. A height-adjustable backrest assembly comprising:
a backrest including a rear side having a coupling groove, with the coupling groove including an opening in a lower end thereof; a connecting member including an upper end coupled to the backrest, with the connecting member further including a lower end adapted to be coupled to a seat or a base, with the upper end of the connecting member received in the coupling groove of the backrest, with the connecting member further including a rear surface, with an abutment member provided on the rear surface of the connecting member, with the abutment member including an end having an outer side, with the abutment member including a first inclined guiding face protruding from the outer side towards a center of the end of the abutment member, with the end of the abutment member further including a first stop face at a side thereof, and with the first inclined guiding face and the first stop face extending beyond the rear surface of the connecting member; a positioning button pivotably mounted to the rear surface of the connecting member, with the positioning button including an axle portion having an axle hole, with a pivot extending through the axle hole and pivotably connected to the connecting member, with a positioning section protruding from the axle portion and including a second inclined guiding face and a second stop face, and with the axle portion further including a mounting section through which the axle hole extends; a spring including first and second tangs and a coil portion between the first and second tangs, with the coil portion mounted to the mounting section of the positioning button, with the pivot extending through the coil portion of the spring and connected to the connecting member, with the first tang abutting against the connecting member, and with the second tang abutting against the positioning button; and a positioning board mounted in a location outside of the coupling groove of the backrest, with the connecting member securely received in the coupling groove of the backrest and securely sandwiched between the backrest and the positioning board, with the positioning board including a movement groove extending in a vertical direction, with the movement groove including a rectilinear side corresponding to the axle portion of the positioning button, with the positioning board further including a plurality of positioning grooves spaced from each other in the vertical direction, with the positioning section of the positioning button releasably engaged in one of the plurality of positioning grooves, with each of the plurality of positioning grooves including an upper edge, a lower edge located below the upper edge in the vertical direction, and an inner edge between the upper edge and the lower edge, with the spring biasing the positioning button to pivot relative to the plurality of positioning grooves of the positioning board, with the positioning section of the positioning button abutting the inner edge of one of the plurality of positioning grooves, with an opening between the upper edge and the lower edge of each of the plurality of positioning grooves having a width larger than a width of the positioning section of the positioning button to provide room allowing movement of the positioning button, with the positioning section of the positioning button abutting the lower edge of one of the plurality of positioning grooves when the backrest is moved to adjust a height of the backrest relative to the connecting member, with a bottommost one of the plurality of positioning grooves including an extension extending from the lower edge thereof, with the positioning board further including a transfer groove formed below the bottommost one of the plurality of positioning grooves, with the transfer groove receiving the positioning button when the positioning section of the positioning button disengages from the plurality of positioning grooves, with the transfer groove including a first side connected to the rectilinear side of the movement groove, with the transfer groove further including a second side having a rectilinear guiding section connected to the extension of the bottommost one of the plurality of positioning grooves, with the positioning section of the positioning button guided by the rectilinear guiding section of the transfer groove while the positioning button is moving into the transfer groove, with the second inclined guiding face of the positioning button sliding along the first inclined guiding face of the abutment member, with the second stop face of the positioning button abutting against the first stop face of the abutment member to limit the positioning section of the positioning button in a position not aligned with the plurality of positioning grooves, with the movement groove further including a top end having an abutment protrusion, with the positioning section of the positioning button including a top end, and with the abutment section of the positioning button disengaging from the abutment member when the abutment protrusion of the movement groove presses against the top end of the positioning section of the positioning button. |
