Abstract: In an optical disk apparatus for focusing a light beam on a track of an optical disk by using a tracking control loop to perform at least one of recording and reproducing operations upon the optical disk, a loop level calculating unit calculates loop levels of the tracking control loop. A control unit calculates a loop gain of the tracking control loop in accordance with the loop levels of the tracking control loop and compensates for a radial tilt of the optical disk in accordance with the calculated loop gain of the tracking control loop.

Abstract: A positioning control apparatus for controlling a moving member to trace the position of a target member which almost equally repeats the position shift at a predetermined period comprises a position detector for detecting a relative position error, a first adder for adding a delay signal and a position error signal, a signal delay unit for outputting the delay signal which is obtained by delaying an output signal of the first adder at a period corresponding to the position shift of the target member, a second adder for adding the position error signal and the delay signal, a third adder for adding an output of the second adder and the delay signal via a filter, a compensating unit for performing the compensation for offset and/or the compensation for stabilization of the positioning control apparatus based on an output of the third adder, a drive unit for driving the moving member based on an output of the compensating unit, and a delay-amount setting unit for setting the amount of delay of a signal delayed

Abstract: A tilt compensator in an optical disk drive detects an optimum tilt setting of the objective lens with respect to a reference plane of the optical head, which allows the optical head to obtain an optimum characteristic of a disk signal at a specified radial position of an optical disk. The optimum tilt setting is corrected at a desired track of the optical disk by using a difference between a first tilt angle of the reference plane with respect to the optical disk measured at the specified radial position and a second tilt angle of the reference plane measured at a desire track of the optical disk. The disk signal is a RF signal, a jitter of the encoded RF signal, a tracking error signal or a wobble signal.

Abstract: In an optical disk apparatus for focusing a light beam on a track of an optical disk by using a tracking control loop to perform at least one of recording and reproducing operations upon the optical disk, a loop level calculating unit calculates loop levels of the tracking control loop. A control unit calculates a loop gain of the tracking control loop in accordance with the loop levels of the tracking control loop and compensates for a radial tilt of the optical disk in accordance with the calculated loop gain of the tracking control loop.

Abstract: A positioning control apparatus for controlling a moving member to trace the position of a target member which almost equally repeats the position shift at a predetermined period comprises a position detector for detecting a relative position error, a first adder for adding a delay signal and a position error signal, a signal delay unit for outputting the delay signal which is obtained by delaying an output signal of the first adder at a period corresponding to the position shift of the target member, a second adder for adding the position error signal and the delay signal, a third adder for adding an output of the second adder and the delay signal via a filter, a compensating unit for performing the compensation for offset and/or the compensation for stabilization of the positioning control apparatus based on an output of the third adder, a drive unit for driving the moving member based on an output of the compensating unit, and a delay-amount setting unit for setting the amount of delay of a signal delayed

Abstract: A tile actuator of an object lens in an optical disk device is controlled by a tilt controller that includes a filter for stopping a signal with first resonance frequency of the tilt actuator, a filter for amplifying a signal with a frequency less than the rotational frequency of the disk, and a filter for restricting current for driving the tilt actuator.

Abstract: A turntable device of the present invention is applicable to, e.g., an optical disk drive and driven by a spindle motor while supporting an optical disk or similar disk-like recording medium thereon. A turntable assembly is made up of an upper turntable and a lower turntable. The upper turntable includes a projection having a tapered portion, and spring portions. The tapered portion and spring portions cooperate to surely obviate the eccentricity of the disk. The lower turntable includes a recess forming a space for accommodating the spring portions, thereby reducing the overall thickness of the assembly. The turntable device is therefore highly portable and small size.

Abstract: A disk supporting device has a spacer member which is placed close to the rim of a disk stored within a cartridge, and gently holds the rim of disk while the apparatus is put out of use; and a spacer releasing mechanism which, when the apparatus is put to use, is activated by a lever for opening/closing a shutter placed outside the cartridge, to displace the spacer member away from the disk in a radial direction of disk to separate the former from the latter. Further, the spacer member is so formed as to have a groove in the form of a rectangular indent on a side opposite to the disk for holding the latter. Through this constitution it is possible to obtain a disk supporting device which does not change its position with respect to the cartridge base whether the apparatus is put to use or out of use, and to produce a cartridge on the whole uniformly thin and allowing a good productivity.

Abstract: A stepping motor has Hall elements which detect the position of the rotor and which output detection signals that have the same period as the excitation period, and which leads the position of the rotor by 90 degrees. The stepping motor is driven by the output of a drive current that is obtained by multiplying the detection signals output from the Hall elements with a torque command signal that controls the output torque of the stepping motor.

Abstract: A method of controlling a transportation velocity of a printhead carriage of a serial printer is disclosed. The printhead carriage is driven by a motor via a timing belt. First, a characteristic equation, which includes a motor speed, a current applied to said motor, an equivalent disturbance indicating environmental variations affecting said motor speed, is discreted. Thereafter, the equivalent disturbance is estimated using the characteristic equation which has been discreted. A value of the equivalent disturbance is determined and subsequently, a value of the equivalent disturbance compensating level is calculated using a discrete low pass filter. Finally, a current to be applied to said motor is obtained by adding a compensating level of the controller to the level of the equivalent disturbance.