Method of assembling a tape cassette and securing a plate spring and shield plate therein

A method of assembling a magnetic tape cassette comprising;

• upper and lower cassette halves, a plate spring having a press pad attached thereto in the vicinity of a front opening in said cassette for receiving a magnetic head, said plate spring being located behind head pins, and a magnetic shield plate is disposed behind said plate spring, said method comprising the steps of:
• fittingly positioning the lower edge of said magnetic shield plate into a shield plate-groove formed on an inner surface of said lower cassette half;
• dropping both left and right ends of said plate spring into respective receiving grooves at the upper ends of a pair of projections formed on said lower cassette half;
• placing said upper cassette half, having resin ribs located thereon, on said lower cassette half so that said upper half and lower half mate and said ribs contact the upper edge of said magnetic shield plate and the upper edge of said plate spring;
• and
• melting said ribs by an ultrasonic welder to fix the position of said magnetic shield plate within said cassette and to hold said plate spring at least in the longitudinal direction of said cassette,
• wherein said projections formed on said lower cassette half are two in number, and said upper cassette half has two suspended portions at positions corresponding to said two projections, and wherein said step of placing said upper cassette half, comprises:
• positioning said upper half such that resin ribs on the bottom facing surfaces of said suspended portions contact the respective upper edges of said plate spring which are opposite the lower edges of said plate spring located in said receiving grooves, and
• further wherein the step of dropping both ends of said plate spring into receiving grooves, comprises:
• placing said plate spring above said receiving grooves of said projections such that the opposite ends of said plate spring slide down sloped walls of said receiving grooves to respective holding portions of said receiving grooves having vertical walls slightly wider apart than the thickness of said plate spring.