Magnetic recording/reproducing apparatus

Abstract: In the apparatus preerase data (4E) is recorded in the area (ARE) erased extra by an erase magnetic head (6A), thereby surely extracting a regenerative clock at the reproducing time. The operation of the regenerative system can be stabilized, correspondingly.

Description: BACKGROUND OF THE INVENTION This invention relates to a magnetic recording/reproducing apparatus, and is more particularly suitably to apply to a floppy disc device for example. Hitherto, in this type of floppy disc device, the desired data are recordable and reproducible by use of an integrated control circuit 2 and a write/read circuit 4 illustrated in Fig. 3. To be specific, in a floppy disc device 1, a control command COMD is inputted to the control circuit 2 from, e.g., a computer, and, at the same time, input data DATA are also inputted thereto. The control circuit 2 herein changes over an operation mode of the floppy disk device 1 in conformity with the control command COMD and drives a mechanical drive circuit (unillustrated) according to the necessity. At this time, in the recording mode, the control circuit 2 causes a fall of an erase control signal XERS and outputs it to the write/read circuit 4, thereby driving an erase magnetic head 6A for a predetermined period. Further, the control circuit 2 simultaneously causes a fall of a write control signal XWGO and sets the write/read circuit 4 in the recording mode. Thereafter, the control circuit 2 sequentially outputs predetermined record data XWDO. Corresponding to this operation, the write/read circuit 4 supplies, when the erase control signal XERS has fallen, a predetermined DC current to the erase magnetic head 6A. The erase magnetic head 6A is herein constructed integrally with a recording/reproducing magnetic head 6B. The magnetic head 6A is arranged to scan a floppy disc in advance of the recording/reproducing magnetic head 6B, thereby erasing the recorded data beforehand with respect to an area scanned by the recording/reproducing magnetic head 6B during a falling period of the erase control signal XERS. Further, the write/read circuit 4 drives, when being set in the recording mode, the recording/reproducing magnetic head 6B by a record current IW determined by an externally attached record current setting resistor 8 in accordance with the record data XWDO sequentially inputted. In the floppy disc device 1, the input data DATA are sequentially thereby recordable in a predetermined format. Namely, as illustrated in Figs. 2A to 2D, in the floppy disc device 1, the input data are recorded on respective recording tracks TR (Fig. 2A) on the sector unit. At this time, predetermined gaps 2 and 3 are formed in front and in rear of the respective input data. Corresponding to this, in the floppy disc device 1, the erase magnetic head 6A is risen in an area of the gap 2, and simultaneously the recording/reproducing magnetic head is fallen in an area of the gap 2, by the falling of write control command WEN (Fig. 2B). With this operation, in the floppy disk device 1, after the erase magnetic head 6A has sequentially recorded the input data DATA in the area erased by the erase magnetic head 6A, the recording operation stops in an area of the gap 3 (Fig. 2C). New input data (indicated by a symbol ND) is recorded between the recorded data (indicated by a symbol OD). In the case of driving the magnetic heads 6A and 6B in this manner, however, the erase magnetic head 6B erases an extra non-record data area by scanning the area ARE in which the erase magnetic head 6A proceeds with respect to the recording/reproducing magnetic head 6B. Hence, it follows that the area in which any data is not recorded exists on the recording track TR. It is difficult to obtain a regenerative signal SRF from this area (Fig. 2D). For this reason, in the floppy disc device 1, a regenerative clock is hard to extract during a period for which the magnetic head 6B scans the above-mentioned area when effecting the reproduction. This presents such a problem that the operation of a regenerative system as a whole becomes unstable. A magnetic recording/reproducing apparatus according to the preamble of claim 1 is described in JP-A-59160513. SUMMARY OF THE INVENTION In view of the foregoing, an object of this invention is to provide a magnetic recording/reproducing apparatus capable of causing the regenerative system to stably operate. The foregoing object and other objects of the invention have been achieved by the features of claim 1. Further, according to the second aspect of the invention, the record current IW is gradually fallen down substantiality a 0 level when recording the erased data (4E). Moreover according to the third aspect of the invention in the magnetic recording/reproducing apparatus the data (4E) erased by the erase magnetic head 6A is recorded in the area ARE erased by the erase magnetic head 6A after stopping an erasing operation of the erase magnetic head 6A, subsequently erase data DS in which the polarity is changed over at a constant cycle is recorded in a state where the record current IW is gradually fallen, and the recording mode is thus ended. Further more, according to the fourth aspect of the invention, there is provided a magnetic recording/reproducing device 20 for recording predetermined input data DATA on a magnetic recording medium in a recording mode, reproducing the data recorded on the recording medium in a reproducing mode and outputting the data, which comprises: a recording/reproducing magnetic head 6B; record current control circuits 12, 14, and 16 for controlling a record current IW of the magnetic head 6B; and a write circuit 14 for outputting the record current IW to the magnetic head 6B by changing over a polarity of the record current IW and thereafter outputting the record current IW to the magnetic head 6B by changing over the polarity of the record current IW in accordance with demagnetization data DS for a predetermined period in the recording mode, the record current being gradually fallen down substantially to a 0 level during a period for which the demagnetization data DS are recorded with the result that the recording mode is ended. Furthermore, according to the fifth aspect of the invention, the record current control circuit 12, 14, and 16 hold the record current to a predetermined value at a rise of the record mode. After stopping the erasing operation of the erase magnetic head 6A, the data (4E) erased by the erase magnetic head 6A is recorded in the area ARE by the magnetic head 6B, and the recording mode is ended. The regenerative signal can be thereby obtained also from the area which is erased extra by the erase magnetic head 6A. The operation of the regenerative system can be stabilized, correspondingly. Further, at this time, the record current IW is gradually fallen down substantially to the 0 level, whereby the C/N ratio of the regenerative signal SRF can be improved. Besides, there are recorded not only the data (4E) erased by the erase magnetic head 6A but also the erase data DS in which the polarity is changed over at a constant cycle in a state where the record current IW is gradually fallen in the wake of the record of the data (4E). The operation of the regenerative system is thus stabilized, and the C/N ration of the regenerative signal can be improved. The record current IW is outputted to the magnetic head 6B by changing over the polarity of the record current IW in accordance with the input data DATA. Thereafter, the record current IW is outputted to the magnetic head 6B by changing over the polarity of the record current IW in accordance with the demagnetization data DS for a predetermined period. During a period for recording the demagnetization data DS, the record current IW is gradually fallen down substantially to the 0 level, and the recording mode is ended. It is therefore possible to surely demagnetize the magnetic head 6B. Further, at this time, upon a rise of the recording mode, the record current IW is held to a predetermined value. Even when demagnetizing the magnetic head, the data is surely recordable from the start of recording. The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a block diagram illustrating a floppy disc in one embodiment of the present invention; Figs. 2A to 2D are signal waveforms diagram of assistance in explaining the operation of a conventional floppy disc device; Fig. 3 is a block diagram illustrating a floppy disc of a conventional; Figs. 4A to 4F are diagrams, depicting signal waveforms, of assistance in explaining the operation thereof; Fig. 5 is a block diagram illustrating the floppy disc device in the second embodiment thereof; Fig. 6 is a signal waveform diagram showing record waveforms thereof; Fig. 7 is a signal waveform diagram illustrating record waveforms in the third embodiment; and Fig. 8 is a signal waveform illustrating the demagnetization data. DETAILED DESCRIPTION OF THE INVENTION Preferred embodiments of this invention will be described with reference to the accompanying drawings: First Embodiment A floppy disc device designated generally at 10 in Fig. 1 controls a write/read circuit 14 by a control circuit 11. Namely, as illustrated in Figs. 4A to 4F, in the control circuit 11, an erase control signal XERS (Fig. 4C) are outputted by a write control command WEN (Fig. 4B) at the same timing with the control circuit 11 (Fig. 1) to the recording tracks TR (Fig. 4A). The write/read circuit 14 is thereby controlled. Further, the control circuit 11 causes, after causing a fall of a write gate signal XWGO (Fig. 4D) concurrently with the write control command WEN, a rise of the write control command WEN and also causes, after a predetermined period has elapsed, a rise of the write gate signal XWGO. With this operation, in the floppy disc device 10, after stop-controlling the operation of the erase magnetic head 6A, the recording/reproducing magnetic head 6B is held in a recording state till the recording/reproducing magnetic head 6B completely scans the area erased by the erase magnetic head 6A. Further, the control circuit 11 outputs the input data in a predetermined format during a falling period of the write control command WEN, generates predetermined data inwardly during a period from a rising of the write control command WEN to a falling of the write gate signal XWGO, and outputs the data generated inwardly following the input data DATA. With this operation, in the floppy disc device 10, the erase magnetic head 6A performs the record in the area erased by the erase magnetic head 6A without exception. A discontinuity of the regenerative signals SRF is thereby prevented. More specifically, the write/read circuit 14 inwardly generates the data (corresponding to the input data of a value 4E in this embodiment) to be recorded in the gap 3 as the relevant data. The data concerned is thus recorded (Fig. 4E). With this operation, in the floppy disc device 10, the pre-erase data is rerecorded in the area which is erased extra by the precedent erase magnetic head 6A, and the generation of an unrecorded portion is effectively prevented. Hence, in the regenerative system also, even when extracting the regenerative clock from the regenerative signal SRF, the regenerative signals can be also obtained from the area which is erased extra by the erase magnetic head 6A. The regenerative clock can be thereby surely control operation of the floppy disc device 10. Based on the construction given above, the data recorded in the area concerned is rerecorded in the area erased extra by the precedent erase magnetic head. The regenerative signal is also thereby obtainable from the area erased extra by the erase magnetic head, thereby stabilizing the operation of the whole of the regenerative system by surely extracting the regenerative clock. Second Embodiment As depicted in Fig. 5, in accordance with this embodiment, a floppy disc device 20 supplies a power supply Vcc to a record current setting resistor 8 through a transistor 12. Further, in the floppy disc device 20, a capacitor 13 is connected between a base and a collector of the transistor 12, whereby the power supply Vcc is supplied via a resistor 16 to the base. With this operation, in the floppy disc device 20, a terminal voltage of the record current setting resistor 8 is fallen at a predetermined time constant in accordance with an OFF operation of the transistor 12. Corresponding to this, the control circuit 22 rises a signal level of a demagnetizing control signal DMAG during a period for which the recording/reproducing magnetic head 6B scans the area which is erased extra by the erase magnetic head 6A. With this operation, in the floppy disc device 20, when recording the pre-erase data (i.e., indicated by 4E in Fig. 6) in the area erased extra by the erase magnetic head 6A, the terminal voltage of the record current setting resistor 8 is gradually fallen. The record current IW is fallen down substantially to a 0 level just before completing the scan over the relevant area. Hence, in the floppy disc device 20, the record current IW is gradually fallen, whereby a residual magnetization of the recording/reproducing magnetic head 6B can be reduced. The recording/reproducing magnetic head 6B can be thereby demagnetized by effectively utilizing the area erased extra by the erase magnetic head 6A. As a matter of fact, in this type of floppy disc device, when improving the recording density by decreasing the record wavelength, a C/N ratio of the regenerative signal is deteriorated, correspondingly. It is difficult to correctly reproduce the data. In this case, when demagnetizing the recording/reproducing magnetic head 6B as in this embodiment, it has proven that the C/N ratio can be improve; and simultaneously a peak shift and an asymmetrical property of the regenerative signal can be also ameliorated. Based on the construction of Fig. 5, the operation of the regenerative system is stabilizing by causing the gradual fall of the record current and rerecording the pre-erase data in the extra-erased area. Simultaneously, the C/N ratio of the regenerative signal can be improved. Third Embodiment As illustrated in Fig. 7, in accordance with this embodiment, the pre-erase data (4E) is recorded for a predetermined period in the area erased extra by the erase magnetic head 6A. Thereafter, the predetermined erase data DS is subsequently recorded. At this time, in the write/read circuit, the record current is inverted at a clock cycle of the record data, thereby generating the data having a duty ratio of 50 [%]. The data is recorded as the record data DS on the floppy disc. Thus, in the floppy disc device, the demagnetization data having duty ratio of 50 [%] as shown in Fig. 8 is generated in this way and recorded while causing the gradual fall of the record current. The recording/reproducing magnetic head 6B can be thereby surely demagnetized. The C/N ratio of the regenerative signal can be improved, correspondingly. Further, the pre-erase data is rerecorded in combination,thus stabilizing the operation of the regenerative system. Further, when completing the demagnetization while rising the signal level of the control signal DMAG during the output period of the demagnetization data DS, a capacitor 13 is charged with the electricity for standing by the record of the subsequent record data. The data immediately after starting the record can be surely recorded, correspondingly. With this operation, the C/N ratio of the regenerative signal can be improved without deteriorating the data just after starting the record. Besides, a peak shift of the regenerative signal and an asymmetrical property can be improved. Other Embodiments Note that the embodiments discussed above have dealt with the case where the magnetic head is demagnetized by use of the demagnetization data in which the signal level is inverted at the clock cycle of the record data. The present invention is not, however, limited to this case. Various data are applicable to the demagnetization data according to the necessity. Moreover, the embodiment discussed above has dealt with the case where the present invention is applied to the floppy disc device in which the demagnetization magnetic head and the recording/reproducing magnetic head are integrally formed. The present invention is not, however, limited to this. The present invention is applicable to various floppy disc devices and further widely to a variety of recording/reproducing devices such as hard disc devices without being limited to the floppy disc devices. As discussed above, according to the present invention, the pre-erase data is rerecorded in the area erased extra by the erase magnetic head, thereby surely extracting the regenerative clock at the reproducing time. The operation of the regenerative system can be stabilized, correspondingly.

Claims: A magnetic recording/reproducing apparatus comprising: an erase magnetic head (6A) which scans an area (ARE) on a magnetic data recording medium in a recording mode, a subsequent recording/reproducing magnet head (6B) which scans the area (ARE), a write/read circuit (14), which generates data for erasing by said erase magnetic head (6A) and which writes and/or reads information using said recording/reproducing magnetic head (6B), wherein a predetermined record current (IW) is at the time of scanning of said recording/reproducing magnetic head (6B) supplied to said recording/reproducing magnetic head (6B) by changing over a polarity of the record current (IW) in accordance with input data, and the input data (DATA) is recorded on a predetermined recording medium through said recording/reproducing magnetic head (6B), characterized in that said write/read circuit (14) comprises means for writing data (4E) by said recording/reproducing magnetic head (6A) in an area of said medium being erased extra by the precedent erase magnetic head (6A), so that an unrecorded portion is prevented and during reproduction of said data a regenerated clock signal is obtained. The magnetic recording/reproducing apparatus according to claim 1, wherein the record current (IW) is gradually falling down substantially to a 0 level when recording the erased data. The magnetic recording/reproducing apparatus of claims 1 or 2, wherein: data erased by said erase magnetic head (6A) is recorded in an area erased by said magnetic head (6A) after stopping an erasing operation of said erase magnetic head (6A), subsequently erase data in which the polarity is changed over at a constant cycle is recorded in a state where the record current (IW) is gradually falling, and the recording mode is thus ended. The magnetic recording/reproducing apparatus of any of the preceding claims further comprising: a record current control circuit (11) for controlling the record current (IW) of said recording/reproducing magnetic head (6B); and wherein the write circuit (14) outputs the record current (IW) to said recording/reproducing magnetic head (6B) by changing over a polarity of the record current (IW) and thereafter outputs the record current (IW) to said magnetic head (6B) by changing over the polarity of the record current (IW) in accordance with demagnetization data for a predetermined period in the recording mode, the record current (IW) being gradually falling down substantially to a 0 level during a period for which the demagnetization data are recorded with the result that the recording mode is ended. The magnetic recording/reproducing apparatus according to claim 4, wherein said record current control circuit (11) and said write/read circuit hold the record current (IW) to a predetermined value at a rise of the recording mode.

Inventors: FUJIMOTO YOSHIHIRO, GOTO SATOSHI, TAGUCHI KEIICHI, YANAGA MASAHARU, YANAGIYA KEIICHI, FUJIMOTO, YOSHIHIRO, GOTO, SATOSHI, TAGUCHI, KEIICHI, YANAGA, MASAHARU, YANAGIYA, KEIICHI
Applicants: SONY CORP, SONY CORPORATION
Application year: 1992
Main classification: G11B5
IPC codes: G11B5, G11B20, G11B19