Patent ID: 7614697

Claim:
A coupling mechanism between a seat and a back of a chair to prevent the seat from tilting with reclining of the back, comprising a pair of opposite front pivotal ear parts and a pair of opposite rear pivotal ear parts secured on a joining base member on a bottom of a seat of a chair; each of the front and the rear pivotal ear parts having a through hole thereon; a joining member securely joined on a supporting tube for the seat; the joining member having two opposite lateral wall portions; each of the lateral wall portions having a sloping slot on each of front and rear portions thereof; the sloping slots each sloping downwards towards a rear end thereof; the seat being joined on the joining member in a movable manner with a first pivotal shaft being passed through the through holes of the front pivotal ear parts and the front sloping slots of the joining member, and with a second pivotal shaft being passed through the through holes of the rear pivotal ear parts and the rear sloping slots of the joining member; each of the lateral wall portions of the joining member having an adjustment slot between the front and the rear sloping slots thereof; a connecting member joined to the back; the connecting member having a fixing hole on a front portion thereof, and a sloping slot on a rear portion thereof; the sloping slot sloping upwards towards a rear end thereof; the connecting member and the joining member being joined together with a third pivotal shaft being passed through the adjustment slots of the joining member and the fixing hole of the connecting member, and with said second pivot shaft being passed through the sloping slot of the connecting member; the connecting member having a pivotal portion between the fixing hole and the sloping slot thereof; the connecting member being pivoted to the joining member at the pivotal portion thereof.