Ink ribbon cassette and method of replacing ink ribbon film

An ink ribbon cassette comprising:

• an ink ribbon unit having a supply bobbin, a take-up bobbin and an ink ribbon film that is wound around said supply bobbin and said take-up bobbin, said supply bobbin having a first pair of circular end portions and said take-up bobbin having a second pair of circular end portions;
• a first housing part having a pair of first semi-cylindrical bobbin housing portions, each of said first housing portions having two end portions, first portions of said supply and take-up bobbins being housed in said first pair of bobbin housing portions, respectively, such that said supply and take-up bobbins are parallel and spaced apart from each other at a predetermined interval;
• a second housing part having a pair of second semi-cylindrical bobbin housing portions, each of said second housing portions having two end portions, second portions of said supply and take-up bobbins being housed in said second pair of bobbin housing portions, respectively, such that said supply and take-up bobbins are parallel and spaced apart from each other at said predetermined interval;
• coupling mechanisms for coupling said second housing part to said first housing part so that said first pair of bobbin housing portions correspond with and are opposed to said second pair of bobbin housing portions, respectively;
• respective holding mechanisms arranged at said two end portions of each of said first bobbin housing portions or at said two end portions of each of said second bobbin housing portions, said holding mechanisms detachably holding said first pair and second pair of end portions of said supply bobbin and said take-up bobbin, respectively;
• each of said holding mechanisms including a bobbin holding portion, each of said bobbin holding portions including (i) a semicircular portion having substantially the same diameter as that of the corresponding end portion of said supply bobbin and said take-up bobbin;
• and (ii) a pair of extensions provided at two end portions of said semicircular portion, ends of said pair of extensions being spaced apart from each other to define a gap therebetween so that said corresponding end portion of said supply bobbin and said take-up bobbin can be inserted through said gap to be detachably held in the corresponding bobbin holding portion.