Patent attributes
A backrest adjusting device includes a fixing plate fixed to a chair seat. A block is pivotably received in a groove in a coupling seat fixed to the fixing plate. A portion of the fixing plate is received in a recess of a positioning board including a vertical slot and a plurality of vertically spaced slanted positioning holes in communication with the vertical slot. A positioning peg on the coupling seat is biased by an elastic element into one of the positioning holes. An engaging board is received in the recess and includes a sliding groove for slideably receiving a guide plate through which the peg extends. A back board is fixed to the positioning board and to a backrest of the chair. The positioning board is vertically movable to adjust a height of the backrest.
