Abstract: An object of the present invention is to minimize an overhead attributable to internal control and to provide a CDR type disk unit in which even when a head moves over a zone boundary, a sector pulse indicating a destination sector can be generated reliably without waiting for an index pulse. The disk unit includes a processing unit; a sector pulse generation unit which generates a sector pulse according to a signal written in the servo information on medium surface; and a format control unit which starts the formatting control when said sector pulse is received after a activating command is received from said processing unit; a target sector detection unit which detects the instant when said head reaches the target sector. The sector pulse generation unit stops outputting the sector pulses to the format control unit from when the access operation starts until a target pulse is received from the target sector detection unit.

Abstract: An FSK signal receiving device is constituted by a first phase shifting circuit for applying a first phase shift to a first reception base band signal of first and second reception base band signals having orthogonal phases to generate a third base band signal, and generating a fourth base band signal having a phase orthogonal to the phase of the third base band signal, a second phase shifting circuit for applying the first phase shift to the second base band signal to generate a fifth reception base band signal, and a logical gate circuit for performing an exclusive OR operation on the third and fourth base band signals to obtain a first output signal, on the third and fifth base signals to obtain a second output signal, and on the first and second output signals to generate a detection signal.

Abstract: A magnetic disk drive which releases adhesion between a magnetic head and a magnetic disk by radially moving the head before the disk begins to rotate. The head movement is accomplished by compressing an elastic stopper by driving a head actuator motor with drive current which flows at half of the voltage previously applied to a motor drive circuit. This is accomplished by grounding one terminal of the motor and forcing all of the motor drive transistors OFF except for one transistor in the motor drive circuit. This provides the benefit that smaller and cheaper transistors can be used and power consumption is considerably reduced, thus contributing to a smaller, cheaper drive circuit which consumes less power.

Abstract: A motor rotation speed control circuit fabricated in an LSI, a first counter which, after being reset by each rotation of the motor, begins counting clock pulses. Bit-outputs of the first counter are led out of the LSI package of the LSI, and are selectively connected to external input lead terminals of a plurality of gate circuits, each of which detects when the first counter has counted a number determined by sum of the input bit-outputs. One gate circuit detects a first reference count-number N.sub.a, which is smaller than a probable least count-number corresponding to, for example, a lower limit of tolerance of the motor speed, considering future possible changes of the motor speed. After being reset by a reset signal corresponding to the first refernece number N.sub.a input thereto, a second counter, preset with a second reference count-number N.sub.b, starts to count the clock pulses. The second reference count-number N.sub.b is chosen so that N.sub.a +N.sub.b =N.sub.0, N.sub.

Abstract: An apparatus for measuring the quantities of chemical substances contained in a solution to be assayed by using a chemical-substance sensitive sensor consists of a potentiometric electrode which responds selectively to chemical substances, and a liquid-junction type reference electrode including a tube, a porous thread member housed in the front end opening of the tube and having a pore capacity of 0.2 cc/g or more and at least the surface of which is hydrophilic, a silver-silver chloride wire is provided and housed in the tube so that at one end of the wire is in contact with the thread member and the wire which extends along the tube. The wire is connected to a connector at the other end opening of the tube, an electrical insulating resin fills said tube, at least at the front end portion thereof, for fixing both the silver-silver chloride wire and the thread member by contact therewith and for stopping said tube. An internal solution is retained by suction in said porous thread member.