Magnetic tape cassette with tape protective sliding closure and lock mechanism for sliding closure

Abstract From the Canadian patent

A magnetic tape cassette is provided with a pivotal closure lid pivotably secured to opposite edges of a casing for movement between a closed position in, which the front opening of the casing through which a magnetic tape can be extracted for loading onto a rotary head while not in use, and an open position wherein the closure lid is pivoted away from said opening to allow access to the tape while in use, is also provided with a sliding closure member slidably mounted on one face of the casing and cooperative with the aforementioned pivotal closure lid, which sliding closure member is held either in a closed position while the pivotal closure lid is in its closed position to cover a bottom …