System and method for cartridge detection and verification using signal comparison

A data storage drive comprising:

• a light source;
• a first photodetector;
• a second photodetector;
• and
• a microprocessor, said data storage drive adapted to receive a cartridge comprising:
• a body;
• a data storage medium on said body;
• and
• a marker on said body, said marker being a material which receives irradiance from said light source and transmits irradiance one of nondirectionally and directionally toward said first and second photodetectors for detection, said microprocessor determining a type of cartridge responsive to an output of said first photodetector and an output of said second photodetector.

The combination of a data storage drive and a cartridge for said drive, said drive comprising:

• a light source;
• a first photodetector;
• a second photodetector;
• and
• a microprocessor, said cartridge comprising:
• a body;
• a data storage medium on said body;
• and
• a marker on said body, said marker being a material which receives irradiance from said light source and transmits irradiance one of nondirectionally and directionally toward said first and second photodetectors for detection, said microprocessor determining a type of cartridge responsive to an output of said first photodetector and an output of said second photodetector.

A method of identifying a type of data storage cartridge having a marker, comprising the steps of:

• disposing a source of irradiance approximately directly beneath an edge of the marker;
• disposing a first photodetector approximately directly beneath the center of the marker;
• disposing a second photodetector adjacent to said source of irradiance;
• irradiating the marker with said source of irradiance;
• detecting irradiance transmitted from the marker at said first photodetector and said second photodetector;
• and
• determining the type of data storage cartridge responsive to said detected irradiance, comprising comparing said detected irradiance at said first photodetector with said detected irradiance at said second photodetector,
• wherein when said detected irradiance of said first photodetector has an intensity that is not less than an intensity of said detected irradiance of said second photodetector it is determined that said marker on the cartridge is transmitting irradiance nondirectionally, and when said intensity of said detected irradiance of said first photodetector is less than said intensity of said detected irradiance of said second photodetector it is determined that said marker on the cartridge is transmitting irradiance directionally.