Pinch preventing mechanism for a collapsible chair

A collapsible chair comprising:

• a backrest frame including two lateral sides each having a lower end,
• a seat frame including two lateral sides each having a front end and a rear end, the rear end of each said lateral side of the seat frame including a mounting block securely mounted thereon, the lower end of each said lateral side of the backrest frame being pivotally connected an associated said mounting block,
• two armrests each having a front end and a rear rend, the rear end of each said armrest being pivotally connected to an intermediate portion of an associated said lateral side of the backrest frame,
• two front legs each having an upper end and a lower end, the upper end of each said front leg being pivotally connected to the front end of an associated said armrest,
• two rear legs each having an upper end and a lower end, the upper end of each said rear leg being pivotally connected to an intermediate portion of the associated armrest,
• a pinch preventing mechanism including:
• a pin fixed to one of the rear legs,
• a sleeve slidably mounted around said one of the rear legs and including a locking member and a wedge, the sleeve including a compartment into which the pin extends, a spring being mounted in the compartment and attached between the pin and an end wall defining the compartment, thereby biasing the sleeve downward, the wedge including a bottom surface,
• an engaging device including an upper end pivotally connected to said lower end of an associated said lateral side of the backrest frame, the engaging device further including a lower end pivotally connected to said one of the rear legs in a position below the sleeve, the engaging device including a notch, the wedge being engaged in the notch of the engaging device when the collapsible chair is in an extended status, the locking member of the sleeve being biased by the spring to securely yet releasably engaged with the upper end of the engaging device when the collapsible chair is in the extended status, thereby preventing collapse of the collapsible chair,
• whereby when collapsing the collapsible chair, the sleeve is manually moved upward along said one of the rear legs to disengage the wedge from the notch, the spring exerts a downward force to the sleeve to make the bottom side of the wedge abut against the engaging device to thereby retain the sleeve at a level in which the locking member of the sleeve disengages from the upper end of the engaging device, thereby allowing collapse of the collapsible chair.