Sony Corporation

Other

Michiya Sako

Keiji Narusawa

Norio Shoji

Kazue Takayoshi

Shinichi Watanabe

Hiroshi Takeuchi

Masatoshi Kitada

Shang-Ching Dong

Soon-Gil Jung

Kazue Tokuchida

The present technology relates to a measurement circuit, a driving method, and an electronic instrument capable of reducing power consumption. In the measurement circuit, irradiation light is emitted from the light emitting unit toward the object, and light from the object is received to measure pulse waves or the like. The measurement circuit includes: a light receiving unit that receives light from an object; an integrating unit that performs integration of a current generated in accordance with the reception of the light by the light receiving unit and generates a voltage according to the amount of reception of the light; and a pulse generating unit that generates a pulse signal having a pulse width corresponding to the amount of reception of the light on the basis of the voltage. The present technology can be applied to electronic instruments such as wearable devices, for example.

Measurement circuit, driving method, and electronic instrument

The present invention provides a magnetic recording and reproducing apparatus having an amplifier apparatus, which is switched from a recording state to a readout state based on a control signal, reads out a signal containing a servo signal by the signal readout means, and includes the amplifier apparatus for amplifying the signal with an amplifier and outputting the amplified signal. In addition, the amplifier apparatus filters the signals by the filtering means that allows the high frequency portion of signals to pass through with a first cutoff frequency during a first prescribed time period after the readout state has been initiated; a second cutoff frequency that is lower than the first cutoff frequency during a second prescribed time period after the first prescribed time period has passed; and a third cutoff frequency that is lower than the second cutoff frequency after the second prescribed time period has passed.

Amplifier apparatus and magnetic recording and reproducing apparatus having the same

A write driver circuit for driving a magnetic head applicable to a variety of magnetic heads or magnetic storage media is disclosed. The circuit includes a write current generating section for generating plural types of write current for magnetizing a predetermined area of a magnetic storage medium in a predetermined direction; a switching signal generating section for generating a switching signal for switching among the write currents; a switching section for changing the direction of magnetization through the magnetic head by switching among the write currents based on the switching signal; and an overshoot current generating section for generating an overshoot current for instantaneously increasing the write current when the direction of magnetization is changed by the switching section; wherein the circuit further includes an overshoot current generation signal producing section, and is designed so that the overshoot current is generated based on an overshoot current generation signal produced thereby.

Write driver circuit for driving a magnetic head

A bias circuit for a magneto-resistive head having a bias current output circuit for flowing a bias current through a magneto-resistive head, and a feedback circuit for controlling the bias current from a bias current output circuit by detecting voltage variation across the magneto-resistive head so that a voltage across the magneto-resistive head becomes a predetermined value. The bias current output circuit comprises a regulating circuit for regulating an operation of the bias current output circuit in the bias current output circuit, a control circuit for controlling the regulating circuit to be in a predetermined condition, and a switching circuit for switching a read/write condition for activating the control circuit for the regulating circuit in a non-read condition of the magneto-resistive head. The regulating circuit includes an oscillation suppressing capacitor; and the control circuit for the regulating circuit is a charging circuit for the oscillation suppressing capacitor.

Bias circuit for magneto-resistive head

In order to solve a problem that it takes a long time to shift from a write mode to a read mode when there is a cross talk of an output signal of a recording head to a reproducing amplifier side, there is provided a reproducing amplifier including an amplifier circuit portion having a differential pair of transistors is provided with a switching circuit comprised of switches connected with resistors, which supply a bias voltage to each base of the differential pair of transistors, respectively in parallel. The switching circuit turns on for a write mode period and for a fixed period after a change from the write mode to a read mode to decrease the input impedance of the reproducing amplifier for the periods.

Reproducing amplifier and magnetic recording and reproducing apparatus employing the reproducing amplifier

A write amplifier circuit in a magnetic storage system has a cross coupling circuit and an active damp circuit to supply an improved write current to the head writing the data onto the media within the magnetic storage system. The inclusion of the cross coupling circuit decreases a rise time and a fall time associated with the write current. The active damp circuit reduces the undershoot and ringing of the write current. Thus, the write amplifier circuit is suitable for high speed data storage writing applications requiring minimal distortion of the data written to a magnetic medium. The write amplifier circuit achieves these improvements in the waveform of the write current by incorporating circuit elements and using both a negative feedback path and a feedforward path. In particular, the cross coupling circuit provides a feedforward path within the write amplifier circuit to a first current which creates a second current that is proportional and greater than the first current such that the second current increases the write current available for the head. Similarly, the active damp circuit provides a negative feedback path from the output terminals of the write amplifier circuit to a third current which creates a fourth current that is proportional and greater than the third current such that the fourth current damps an undershoot and ringing associated with the write current.

Architecture for a hard disk drive write amplifier circuit with damping control

A reproducing circuit for a MR head is proposed, wherein a MR head is interposed between a pair of current source circuits and a feedback amplifier is provided for controlling the current of the pair of the current source circuits so that a terminal voltage of the MR head becomes a predetermined value. Reproduced output from the MR head is derived from an amplifier having balanced input terminals for canceling noises and ripple components included in a power source.

Magnetic reproducing apparatus and reproducing circuit to be applied to the apparatus

The overvoltage applied on a head during switching of the head is prevented. At the time when the head switching signal changes, a switch S for turning on/off an operational amplifier Gm is turned off, and the operational amplifier Gm is turned off. Simultaneously, the switch S is turned on, the current source I is connected to a capacitor C , and the capacitor C is discharged. Then, switches S and S for switching the MR head are switched. Finally, the switch S is turned off and the switch S is turned on, thus the switching of the MR head is finished.

Reproduction amplifier circuit of hard disk drive

A magnetic-head short-circuit detector for correctly detecting an electrical short-circuit between coil terminals of a magnetic head. Terminals H.sub.X and H.sub.Y of the magnetic head are connected to the bases of a pnp-transistors P.sub.1 and P.sub.2 respectively. Current sources I.sub.1 and I.sub.2 are inserted between power supply V.sub.CC and the emitters of the transistors P.sub.1 and P.sub.2 respectively. The emitter of the transistor P.sub.1 is connected to the (-) input terminal of a comparator 1 through a resistor R.sub.1 and directly to the (+) input terminal of a comparator 2. The emitter of the transistor P.sub.2 is connected to the (+) input terminal of the comparator 1 through a resistor R.sub.2 and directly to the (-) input terminal of the comparator 2. A current source I.sub.3 is connected between the (-) input terminal of the comparator 1 and GND. A current source I.sub.4 is connected between the (input terminal of the comparator 2 and GND. Based on results of the comparison by the comparator 1 and the comparator 2, a short-circuit on the magnetic head is detected.

Magnetic-head short-circuit detector

A current generating circuit which has a current source, two switches connected in serial between one of the output terminals and a first or second transistor, and a control signal generating circuit that generates a control signal for operating the first and second transistors out of phase. A write current is generated between the output terminals by direct switching of a current supplied to the first and second transistors by the two switches. The dynamic range of the output voltage for a magnetic head in a recording apparatus connected to the output terminals can be made large, and the rising and falling times of the write current can be shortened to result in an improved high speed recording.

Current generating circuit for read/write head

A write current setting circuit of a magnetic recording apparatus which can be reduced in the number of IC pins and enables the increase of the IC pins accompanying an increase in the number of modes to be kept to a minimum. The external resistance elements for generating the sub-mode correction current are connected to a single IC pin. The IC is provided with a current generation circuit and a voltage follower for holding the output voltage at a predetermined value and is provided with a sub-mode switch circuit for switching the connection between the IC pin and the internal power source line and output terminal of the voltage follower in accordance with the input of a correction current control signal. Due to this, while six external resistance elements are required, (2.times.n) modes can be set by (n+1) IC pins of the integrated circuit.

Growing community of inventors

Kagoshima, Japan

Michiya Sako