Cassette detecting and discriminating arrangement in a cassette transport mechanism for loading and unloading tape cassettes of varying sizes and cassettes for use therewith

A cassette transport mechanism for loading and unloading tape cassettes of various sizes into a recording and/or playback unit, said transport mechanism comprising:

• cassette transport means for transporting a first type grooveless tape cassette having a width L and a height T, a second type tape cassette having said height T and a width L' greater than said width L and provided with a pair of grooves formed in an exterior bottom of said second type tape cassette, a third type grooveless tape cassette having said width L and a height T+A greater than said height T, and a fourth type tape cassette having said height T+A and said width L' and provided with a pair of grooves formed in an exterior bottom of said fourth type tape cassette, individually from a first loading position to a second position for a recording or playback operation, said cassette transport means including a cassette tray provided with a pair of projecting portions formed thereon as first and second guide rails in a depthwise direction corresponding to a cassette insertion direction for guiding each cassette, a cassette insertion slot having approximately said height T+A for receiving each of said tape cassettes, said projecting portions being positioned apart widthwise by said width L for guiding either said first or third type grooveless tape cassette between said guide rails or said second or fourth type tape cassette over said guide rails within said grooves of said second or fourth type tape cassette into said cassette insertion slot, and a plurality of cassette detecting means provided at an upper inner portion of said cassette insertion slot for providing detection signals for determining the correct position of said cassette inserted into said cassette insertion slot before loading of said cassette into said recording and/or playback unit, said plurality of cassette detecting means comprising first, second and third cassette detectors provided at said upper inner portion of said cassette insertion slot, said first cassette detector being spaced directly above said first guide rail, said second cassette detector being spaced directly above said second guide rail, and said third cassette detector being located between said first cassette detector and said second cassette detector, wherein said cassette transport means further includes discrimination means for discriminating whether a cassette has been incorrectly inserted into said cassette tray by means of said detection signals obtained from said plurality of cassette detecting means, whereby one of said first and second cassette detectors is activated when one of said tape cassettes having said height T is incorrectly inserted into said insertion slot, and said first and second cassette detectors are not activated when said one of said tape cassettes having said height T is correctly inserted into said insertion slot.