Patent ID: 7364235

Claim:
A chair comprising: a seat; a backrest connected pivotally to said seat; an armrest disposed at a lateral side of said seat, and having a receiving portion; a positioning unit provided in said receiving portion of said armrest, and including a first positioning block formed with a first stop portion, and a second positioning block formed with a second stop portion and spaced apart from said first positioning block in a first direction, each of said first and second stop portions having a height in a second direction substantially transverse to the first direction, the height of said second stop portion being greater than that of said first stop portion; a positioning member retained movably on a rear side of said backrest, and having one end that is extended into said receiving portion of said armrest and that is disposed to abut against a selected one of said first and second stop portions; an operating unit connected to said positioning member and operable to drive movement of said positioning member relative to said backrest and said positioning unit in said receiving portion of said armrest for disengaging said one end of said positioning member from said first and second stop portions and for subsequently engaging said one end of said positioning member with the selected one of said first and second stop portions; and a safety mechanism including a first limit component provided on said backrest, and a second limit component provided on said operating unit, said safety mechanism being operable in one of a limiting state, where said first limit component cooperates with said second limit component so that said one end of said positioning member is displaceable in the second direction in response to operation of said operating unit by a shorter distance sufficient to move past the height of said first stop portion but insufficient to move past the height of said second stop portion, and a non-limiting state, where said first and second limit components permit displacement of said one end of said positioning member in the second direction in response to operation of said operating unit by a longer distance that is longer than the shorter distance and that is sufficient for said one end of said positioning member to move past the height of said second stop portion.