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1. 发明专利

JPH09219004A MAGNETIC HEAD DRIVING CIRCUIT 失效
公开(公告)号：JPH09219004A
公开(公告)日：1997-08-19
申请号：JP5246296
申请日：1996-02-14
申请人： HITACHI LTD , HITACHI COMPUTER ENG , HITACHI COMMUNICATION SYSTEM
发明人： NAGAYA YUJI , YOSHINAGA MAKI , HATANAKA NORIAKI , MOCHIZUKI TAKEO , MORIYA ATSUSHI
IPC分类号： G11B5/09 , G11B5/00 , G11B5/02 , G11B19/02
摘要： PROBLEM TO BE SOLVED: To obtain a magnetic head driving circuit which can write data at high speed by providing the circuit with an auxiliary current source passing a current transiently only at the initial stage at the time of switching a direction of a current flowing in a magnetic head. SOLUTION: Auxiliary current sources SC1, SC2 connected to head terminals X, Y are turned on and turned off by data signals D, the inverse of D in the same way as main current sources MC1, MC2. And when current detecting circuits CD1, CD2 detect a current started to flow in the main current sources MC1, MC2, the auxiliary current sources SC1, SC2 are quickly turned off. Thereby, a current can be increased transiently at the time of switching a direction of a current flowing in a magnetic head L at the time of writing data. Therefore, data can be written at high speed in a magnetic storage device by improving a variation rate of a writing current and shortening a switching time of a writing current.

2. 发明专利

JPH07153002A RECORDER/REPRODUCER CIRCUIT 失效
公开(公告)号：JPH07153002A
公开(公告)日：1995-06-16
申请号：JP29811793
申请日：1993-11-29
申请人： HITACHI LTD , HITACHI COMMUNICATION SYSTEM
发明人： NAGAYA YUJI , HASHIMOTO TAKASHI , MOCHIZUKI TAKEO , HIROSE TAKESHI
IPC分类号： G11B5/39 , G11B5/02
摘要： PURPOSE:To enhance reliability by monitoring a deteriorated state of a magnetoresistance effect type head (MR head) and immediately detecting occurrence of a disconnection or a short-circuit of the head. CONSTITUTION:A potential difference to be applied to a base of a differential transistor from a feedback circuit C.. provided in a memory reproducer 10 is detected, and amplified by a potential difference amplifier 21. This difference is a value responsive to a resistance value RMR of an MR head 1. The difference responsive to the value RMR is amplified and then sent to a short-circuit deciding comparator 23, a disconnection deciding comparator 24. These comparators 23, 24 compare the difference responsive to an aging change of the value RMR of the head 1 with voltage drops by resistance values r11, r12. When the head becomes a disconnection or a short-circuit by the comparison, its gist is detected by output terminals OUT3, OUT4.

3. 发明专利

JP2000268302A MAGNETIC DISK MEMORY DEVICE 失效
公开(公告)号：JP2000268302A
公开(公告)日：2000-09-29
申请号：JP7129599
申请日：1999-03-17
申请人： HITACHI LTD , HITACHI COMMUNICATION SYSTEM
发明人： HIROSE TAKESHI , MOCHIZUKI TAKEO , NAGAYA YUJI
IPC分类号： G11B5/09 , G11B5/02
摘要： PROBLEM TO BE SOLVED: To allow the S/N ratio to be improved by providing a bias circuit with a resistance value sufficiently larger than that of an MR head, and performing switching-control for first and second resistance elements which provide a first potential to an interconnection point, a first constant current source MOSFET that supplies a bias current to these elements, and a second MOSFET that supplies another bias current corresponding to the bias current. SOLUTION: In an MR head corresponding to another magnetic recording surface in which a readout signal is amplified by a read amplifier Amp and read out via a post amplifier and an output circuit, MOSFETs Q5, Q6 are set in the OFF condition so that no readout operation is performed. Since MOSFETs Q2, Q4 constituting a constant current are provided with resistor R2, R5 at their sources, respectively, their transconductance Gm as an amplifying element is lowered due to their negative feedback function. Accordingly, inductive gate noise components to be superposed over constant currents that are to be output from drains of the MOSFETs Q2, Q4 are made small.

4. 发明专利

JPH11195202A MINUTE SIGNAL AMPLIFYING DEVICE AND MAGNETIC DISK MEMORY USING THE SAME 失效
公开(公告)号：JPH11195202A
公开(公告)日：1999-07-21
申请号：JP25299898
申请日：1998-09-07
申请人： HITACHI LTD , HITACHI COMMUNICATION SYSTEM , HITACHI ULSI SYS CO LTD
发明人： HASHIMOTO TAKASHI , NAGAYA YUJI , YOSHINAGA MAKI , HATANAKA NORIAKI , MOCHIZUKI TAKEO , SONOYAMA KATSUYA
IPC分类号： G11B5/09 , G11B5/00 , G11B5/012 , G11B5/02 , G11B5/11 , G11B5/40 , G11B5/48 , G11B19/04 , G11B23/00 , H03F3/45
摘要： PROBLEM TO BE SOLVED: To amplify a minute signal over a wide band with a high sensitivity with a simple constitution by using a modified differential circuit consisting of two pieces of conduction type transistors. SOLUTION: A P type MOSFET-MP2 and an N type MOSFET-MN1 are made one pair and they are made a modified differential form by connecting their sources in series. An output signal is taken out from the load element provided between the MN1 and a power source ultage VDD by applying an input voltage signal on the control terminal of the MP2 and a DC bias on the control terminal of the MN1. The minute voltage signal read out from a magnetic disk by a voltage sensing system is directly applied between gates of the MP2 and the MN1 and an amplified signal is obtained by taking out a current correspondingly flowing through the load element. Thus, a highly sensitive amplifying operation having a high S/N ratio is made possible by directly amplifying the minute voltage signal by the modified differential circuit. Moreover, since power sources of this device, that is, an operating voltage VDD and a motor driving voltage VMO can be generated from one power source POW, the miniaturizing and the lowering of the cost of the device are attained.

5. 发明专利

JPH08138201A LEAD AMPLIFIER, REPRODUCING CIRCUIT AND MAGNETIC DISK DEVICE 失效
公开(公告)号：JPH08138201A
公开(公告)日：1996-05-31
申请号：JP29889194
申请日：1994-11-08
申请人： HITACHI LTD , HITACHI COMMUNICATION SYSTEM
发明人： NAGAYA YUJI , HASHIMOTO TAKASHI , HIROSE TAKESHI , YOSHINAGA MAKI , HATANAKA NORIAKI , MOCHIZUKI TAKEO
IPC分类号： G11B5/027 , G11B5/02 , G11B5/09 , G11B5/39
摘要： PURPOSE: To reduce the influence of a differential amplifier gain on a resistance value in a MR head by coupling the control terminal of a first transistor with one end of the MR head and differentially coupling a second transistor with the first transistor. CONSTITUTION: A reproducing circuit is formed of a first transistor Q17 having a control terminal coupled with one end of an MR head, a second transistor Q18 to be differentially coupled with the first transistor and a feedback circuit 13 for sending feedback to the other end of the MR head and the control terminal of the second transistor Q18. In this case, a lead amplifier of a current bias voltage sensing type is realized and therefor the influence of the reduced value in the MR head on a differential amplifier gain is reduced.

6. 发明专利

JPH06274805A READ/WRITE INTEGRATED CIRCUIT 失效
公开(公告)号：JPH06274805A
公开(公告)日：1994-09-30
申请号：JP8543093
申请日：1993-03-19
申请人： HITACHI LTD , HITACHI COMMUNICATION SYSTEM
发明人： YOSHINAGA MAKI , NAGAYA YUJI , HIROSE TAKESHI , HATANAKA NORIAKI , HIRAI TOMOAKI , MOCHIZUKI TAKEO
IPC分类号： G11B5/00 , G11B5/012 , G11B5/02 , G11B5/40 , G11B5/455 , G11B5/48 , G11B19/02 , G11B19/04 , G11B20/18 , H03F3/45 , H03F3/72
摘要： PURPOSE:To speed up write operation by respectively providing the damping resistors of a magnetic head driving circuit between both ends of a magnetic head and a clamping part. CONSTITUTION:The damping resistor Rd is connected between the magnetic head 5 and a clamping circuit. In such a constitution, since the level of a magnetic head terminal is equal to that of the clamping circuit, a current ID flowing through the resistor Rd becomes nearly zero, and the head voltage of the magnetic head 5 is returned to a stationary level when the switching of the current is finished, and the current flows through the resistor Rd to suppress the overshoot. The voltage V is increased, and the resistor Rd is decreased since the unwanted current ID at the time of switching the current becomes nearly zero. In such a manner, the current shunted from the write current is formed by a transistor Q18, and the logical operation is performed with the shunted current and a mode switching signal formed by an OR gate circuit G3 by the transistor Q27, and a malfunction where the write current flows at a read mode time is detected.

7. 发明专利

JPH10269510A READ AMPLIFIER CIRCUIT AND SEMICONDUCTOR INTEGRATED CIRCUIT 失效
公开(公告)号：JPH10269510A
公开(公告)日：1998-10-09
申请号：JP7600597
申请日：1997-03-27
申请人： HITACHI LTD , HITACHI INFORMATION TECHNOLOGY , HITACHI COMMUNICATION SYSTEM , HITACHI VLSI ENG
发明人： HIROSE TAKESHI , NAGAYA YUJI , HASHIMOTO TAKASHI , YOSHINAGA MAKI , HATANAKA NORIAKI , SOGA YUJI , MORIYA ATSUSHI , MOCHIZUKI TAKEO , KAMEYAMA SADAFUMI
IPC分类号： G11B5/09 , G11B5/02 , H03F3/68
摘要： PROBLEM TO BE SOLVED: To reduce the parasitic capacitance to be connected to each emitter and the noise caused by the base resistance of the transistors for a cascade connection by plurally dividing the cascade connected transistors and connecting a few transistors for a head bias to each emitter. SOLUTION: The collectors of five transistors are connected to the emitter of an upper stage cascade connection transistor Q1. The parasitic capacitance associated with the emitter of the transistor Q1 is 5×Cb and the parasitic capacitance associated with the emitters of lower stage cascade connection transistors Q11 to Q15 becomes 5×CA. Noises generated by the base resistances of the transistors Q1 and the transistors Q11 to Q15 are equal and set to Vn. If the sizes of the transistors Q11 to Q15 and head bias transistors Qb1 to Qb10 are the same and parasitic capacitances of the emitters are CA=Cb, the noise in the read amplifier is reduced to an approximately 1/2 value and the noise reduction effect is obtained at a higher frequency band.

8. 发明专利

JPH08124102A WRITE DRIVER CIRCUIT 失效
公开(公告)号：JPH08124102A
公开(公告)日：1996-05-17
申请号：JP28449094
申请日：1994-10-24
申请人： HITACHI LTD , HITACHI COMPUTER ENG
发明人： HASHIMOTO TAKASHI , HATANAKA NORIAKI , YOSHINAGA MAKI , NAGAYA YUJI , HIROSE TAKESHI , SOGA YUJI , KACHI TADAO
IPC分类号： G11B5/027 , G11B5/00 , G11B5/012 , G11B5/035 , G11B5/09 , G11B5/455 , G11B5/596 , G11B19/02 , G11B19/04 , G11B33/12 , H03K17/615 , H03K17/66
摘要： PURPOSE: To provide a write driver circuit capable of speedily operating the writing even under a low power source voltage. CONSTITUTION: This circuit is provided with first and second PNP input transistors QP1, QP2 whose bases are supplied with a pair of complementary input signals respectively and first and second NPN output transistors Q1, Q2 in inverted Darlington state. A first resistance elements R1 is provided between the emitter of the PNP transistor and the collector of corresponding NPN output transistor and a second resistance element Ra is provided between the collector common for the first and the second NPN output transistors Q1, Q2 and a power source. Clamping voltages are supplied to collectors of the first and the second PNP transistors QP1, QP2 and third and fourth NPN output transistors Q3, Q4 connected respectively to the first and second NPN output transistors Q1, Q2 in serial and complementarily subjected to switch-controls are provided. Thus, an inductive head is driven by consituting a bridge circuit.

9. 发明专利

JPH08160092A SEMICONDUCTOR INTEGRATED CIRCUIT 失效
公开(公告)号：JPH08160092A
公开(公告)日：1996-06-21
申请号：JP29743994
申请日：1994-11-30
申请人： HITACHI LTD , HITACHI COMPUTER ENG
发明人： HIROSE TAKESHI , NAGAYA YUJI , HASHIMOTO TAKASHI , YOSHINAGA MAKI , HATANAKA NORIAKI , SOGA YUJI , MORIYA ATSUSHI
IPC分类号： G01R31/26 , G01R31/02 , H01L21/66 , H01L21/822 , H01L27/04
摘要： PURPOSE: To surely detect head opening abhormality by counting the time during which the voltage between head terminals is lower than a prescribed slicing level and comparing the count value with a preset value. CONSTITUTION: When head opening abnormality occurs, a voltage waveform in which the time during which the flyback voltage between head terminals becomes lower than a slicing level becomes longer than that obatined when no head opening abnormality occurs is obtained. A sense circuit detects the voltage waveform and the input transistor Q51 of a buffer circuit 22 is turned on by, for example, making an electric current to flow to the transistor Q51 from an output terminal IUX, Consequently, the output of the circuit 22 becomes 'L' and the differential transistor Q62 of a timer circuit 23 is turned off, and then, a capacity is charged by means of a collector-side transistor Qp62 and the potential at a node N11 rises. When such a state becomes longer than a preset pariod of time, the potential at the node N11 becomes higher than the reference voltage VR3 of a level discriminated circuit 25 and the output of the circuit 24 is inverted to αHβ from αLβ. The output VOPN which latches 25 the output of the circuit 24 changes to αHβ and the head abnormality detecting signal of a logical gate circuit changes. Therefore, the head opening abnormality can be detected surely.

10. 发明专利

JPH08288765A LIGHT AMPLIFIER AND MAGNETIC DISK DEVICE 失效
公开(公告)号：JPH08288765A
公开(公告)日：1996-11-01
申请号：JP11634195
申请日：1995-04-18
申请人： HITACHI LTD , HITACHI COMPUTER ENG
发明人： NAGAYA YUJI , MORIYA ATSUSHI , MOCHIZUKI TAKAMITSU , HATANAKA NORIAKI , HIROSE TAKESHI , HASHIMOTO TAKASHI
IPC分类号： G11B5/027 , H03F3/30 , H03F3/68
摘要： PURPOSE: To shorten the switching time of a magnetic head. CONSTITUTION: A 1st transistor(TR) pair 21 is constituted of pnp type bipolar TRs Q1, Q2 and a 2nd TR pair 22 is constituted of npn type bipolar TRs Q3, Q4. Thereby restriction due to voltage resistance between the emitters and bases of TRs when the 1st TR pair 21 is formed by npn type bipolar TRs can be removed and high voltage can be impressed between the terminals of the magnetic head 20. Consequently the switching time of the magnetic head 20 can be shortened.

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