Connection control circuit and information storage apparatus
View Patent ↗A connection control circuit having the function of controlling connection and disconnection of an information storage apparatus to and from a transmission line is constructed such that it uses a comparator to determine whether or not the level of operating clock signal output from a controller of the information storage apparatus is within a predetermined range, and if it is detected that the level of the operating clock signal departs from the predetermined range, the connection control circuit outputs a control signal to a by-pass circuit to disconnect the information storage apparatus from the transmission line loop. This enables the information storage apparatus to be disconnected from the loop even if the controller of the information storage apparatus does not function normally due to an abnormality of the clock or an abnormality of the power supply.
1. A connection control circuit which controls connection and disconnection of an information storage apparatus to and from a transmission line, said connection control circuit comprising a comparator which compares the level of a given signal generated in accordance with a state of an occurrence of an operating clock signal of a controller of said information storage apparatus with a threshold level and, in accordance with a result of the comparison, generates a connection control signal for connection or disconnection of said information storage apparatus to or from the transmission line.
2. A connection control circuit according to claim 1 , wherein said connection control circuit comprises a low pass filter for smoothing said operating clock signal of said controller in a stage preceding said comparator.
3. A connection control circuit according to claim 1 , wherein an operating power supply for said controller is different from an operating power supply for said comparator.
4. A connection control circuit which controls connection and disconnection of an information storage apparatus to and from a transmission line wherein, when said connection control circuit detects that a range of a level of a given signal generated in accordance with a state of an occurrence of an operating clock signal of a controller of said information storage apparatus has been deviated from a predetermined range, due to an abnormality in said operating clock signal of said controller of said information storage apparatus or an abnormality in a power supply, said connection a control circuit that outputs a control signal for disconnecting the information storage apparatus from a loop of said transmission line.
5. An information storage apparatus comprising:
an interface unit for inputting and outputting data from and to a transmission line;
a storage medium for storing said data;
a head for reading out or writing information from or into said storage medium;
a controller for performing positioning control of said head relative to said storage medium; and
a connection control circuit for outputting a control signal, to disconnect said interface unit from said transmission line, when it is detected that a range of a level of a given signal generated in accordance with a state of an occurrence of an operating clock signal of said controller has been deviated from a predetermined range, due to an abnormality in said operating clock signal of said controller or an abnormality in a power supply.