Patent ID: 6515946
Filing Date: 2003-02-04
Classification: G11B,Y10S

Abstract:
A medium controller storing a plurality of media therein, having a medium transfer unit to take a medium in and out of a storage place to read or write information on the medium and to transfer the medium to a place where reading and writing information is possible, and managing information about media in storage, comprising:slots for storing media; sensors, each mounted in each of the slots, for detecting whether or not there is a medium in said slot; a sensor manager for holding a log of status of said sensors in a period when media are likely to be taken in or out manually and deciding changes in the status of said sensors; a medium information reader for reading medium information, which identifies a medium, from the medium, wherein when it is decided from a decision result by said sensor manager that the medium has been replaced, medium information is read by said medium information reader to thereby update medium storage information, or when it is decided that the medium has not been replaced, said medium storage information is not updated; a door open detector for detecting that the door is open at the medium storage place of the medium controller; a door closed detector for detecting that the door is closed; a first memory for storing medium management information showing what media are stored in which slots; a second memory for storing medium management information showing what media are stored in which slots at the moment when said door close detector detects that said entry/exit door is closed; wherein said medium storage information is updated by writing said medium information, read in by said medium information reader, in the first and second memories; wherein said sensor manager comprises a sensor status holder for storing current sensor status of the respective slots; a log tracer for holding a log of the sensor status of the respective slots when it is found from contents of the sensor status holder that said entry/exit door is closed; and a log trace determiner for checking status changes in sensors from contents of said log tracer; and wherein with a sensor status that a medium exists being designated as ON and a sensor status that a medium does not exist being designated as OFF, when a decision result of the sensor status decision unit is OFFâ†’ON or ONâ†’ON, said medium information is read in by said medium information reader and when a decision result is ONâ†’OFF, said medium information is erased and when a decision result is OFFâ†’ONâ†’OFF or that the sensor status remains unchanged, said medium information is not read in by said medium information reader.