Rotary head recording and reproducing apparatus

Abstract: A rotary head tape recording and reproducing apparatus drives a rotary drum (3) and a capstan (15) by a common driving motor (2). In the reproducing mode, rotary heads (12A, 12B) generate a scanning position detection signal by picking up an address signal indicating the current scanning position from a recording track, and the driving motor (2) is controlled so as to match the scanning position detection signal with a reference scanning position signal.

Description: This invention relates to rotary head recording and reproducing apparatus. As a rotary head recording and reproducing apparatus, there has been proposed a rotary head type magnetic tape recording and reproducing intended for recording and reproducing a digital audio signal and/or a digital video signal. In such apparatus, a rotary magnetic head mounted on a rotary drum scans a magnetic tape employed as a recording medium. The tape is advanced in a running direction lengthwise and the rotary magnetic head scans the tape slantwise (see Japanese laid-open patent publication 58/208915). This kind of rotary head recording and reproducing apparatus requires a tape loading mechanism to draw out a magnetic tape from a tape cassette, and a capstan to drive the magnetic tape around the rotary drum along a predetermined arc or wrap angle. Such a tape recorded driving system includes two motors, one for driving the capstan and the other for driving the rotary drum. In such a two-motor driving system, the motors are independent of each other, namely the drum motor for driving the rotary drum and the capstan motor for driving the capstan, and servo control of the drum motor and capstan motor is necessary to coordinate their operation. According to the present invention there is provided a rotary head tape recording and reproducing apparatus for recording or reproducing an information signal including address data on or from recording tracks formed on a magnetic tape across a longitudinal direction of said magnetic tape, the apparatus comprising: rotary head means; head drum means mounting the rotary head means and supporting a magnetic tape wound around the head drum means along a predetermined wrap arc, the rotary head means recording or reproducing the information signal on or from the magnetic tape; capstan means for driving the magnetic tape; transmission means connected to the head drum means and the capstan means; common motor means for driving the transmission means, the head drum means and the capstan means, at least the head drum means and the capstan means being driven in rotation; reference means for generating first and second reference signals; comparison means for comparing the first reference signal with a first output signal representing a rotational state of the rotary head to produce a first comparison signal and for comparing the second reference signal with a second output signal representing address data reproduced from the magnetic tape by the rotary head means to produce a second comparison signal; and servo control means operative in a recording mode for controlling the common motor means in accordance with the first comparison signal and in a reproducing mode for controlling the common motor means in accordance with the second comparison signal. The invention will now be described by way of example with reference to the accompanying drawings, throughout which like parts are referred to by like references, and in which: Figures 1 and 2 are block diagrams showing rotary head recording and reproducing apparatus typical of apparatus to which the present invention can be applied; Figure 3 is a block diagram representing one embodiment of a rotary head recording and reproducing apparatus according to this invention; Figure 4 is a schematic diagram showing an apparatus in the embodiment of Figure 3 for driving a rotary drum and a capstan; Figure 5 is a diagrammatic developed plan view showing a scanning path on a magnetic tape; Figure 6 is a block diagram showing a specific configuration of a recording/reproducing circuit; Figures 7A, 7B, 8 and 9 are block diagrams showing the detailed construction of the embodiment; Figures 10A to 10C are schematic diagrams showing a format of track data; Figure 11 is a schematic diagram showing scanning paths on a magnetic tape; and Figures 12A to 12C, 13A to 13C, and 14A to 14C are signal waveform diagrams serving for illustration of a servo operation for tracing scanning paths SCN1 to SCN3 of Figure 11. (1) Apparatus to Which the Invention can be Applied The present invention can be applied to recording and reproducing apparatus shown by way of example in Figures 1 and 2. In a two-motor driving device 1 shown in Figure 1, a magnetic tape 6 from a feed reel 5 of a tape cassette 4 is threaded around a rotary drum 3 driven by a drum motor 2 to a take-up reel 11. The tape 6 also passes around a pinch roller 7 and a guide roller 8 positioned on one side of the rotary drum 3 and a guide roller 9 and a pinch roller 10 positioned on the other side of the rotary drum 3. The magnetic tape 6 runs helically in a direction generally indicated by an arrow K1 around the rotary drum 3, and a pair of rotary magnetic heads 12A and 12B mounted on the rotary drum 3 rotate at high speed in the direction indicated by an arrow K2. Digital audio data supplied from a recording/reproducing circuit 13 at the time of recording are recorded on a recording track on the tape 6, and the digital audio data are picked up from the recording track at the time of reproducing and supplied as an input to the recording/reproducing circuit 13, thereby reproducing the audio signal. A phase comparator circuit 21 is provided on a driving system of the rotary drum 3. A detection pulse signals S1 indicating a rotary phase of the rotary drum 3 is generated by a pulse generator (PG) 22. The phase is compared with the phase of a reference pulse signal S REF at the phase comparator circuit 21. A phase error signal S2 is supplied by the phase comparator circuit 21 to a drive amplifier circuit 23, which generates a drive output S3 for adjusting the drum speed in such a manner as to remove the phase difference from the signal supplied to the drum motor 2. Thus the rotary drum 3 is rotated and driven at a rotary phase synchronized with the reference pulse signal S REF . A frequency comparator circuit 25 is provided in a driving system for a capstan 15. A frequency detection signal S5 is a pulse signal indicating the rotational speed of the capstan 15 and is generated by a frequency generator (FG) 26. The signal S5 is supplied to the frequency comparator circuit 25 through a switching input terminal REC of a switching circuit 27 during recording, so that the frequency is compared with a frequency of the reference pulse signal S REF . A frequency error signal S6 indicating the frequency deviation is supplied to a drive amplifier circuit 28. The drive amplifier circuit 28 supplies a drive output S7 to a capstan motor 14. Thus the rotational speed of the capstan 15, and accordingly the running speed of the tape 6, are controlled to a value determined by the frequency of the reference pulse signal S REF at the time of recording. That is, the tape running speed is adjusted by the capstan 15 in such a manner as to eliminate any frequency error indicated by the signal S6. During playback, a control signal (CTL signal) S8 recorded on the tape 6 is picked up by a fixed magnetic head 29, and thus a tape feed signal S9 comprising a pulse signal indicating the running state of the tape 6 is supplied to the frequency comparator circuit 25 through a switching input terminal PB of the switching circuit 27 during playback. The frequency comparator circuit 25 controls the rotational speed of the capstan 15 so as to synchronize the running state of the tape 6 with the reference pulse signal S REF . In the system described above, the two motors 2 and 14 are independent of each other. Thus the drum motor 2 and the capstan motor 14 respectively provided for driving the rotary drum 3 and the capstan 15 must be subjected to a servo operation by means of separate servo systems. The structure is therefore complicated and expensive. A one-motor driving device 31 shown in Figure 2 may be considered for solving the aforementioned problem. Parts of Figure 2 corresponding to those of Figure 1 are indicated by the same reference characters. An electromagnetic brake type transmission device 32 is provided instead of the capstan motor 14 of Figure 1 and the drive amplifier circuit 28 for driving it. The rotation of the rotary drum 3 is coupled to an input shaft of the transmission device 32 through a belt 33. An output shaft 34 is coupled to the capstan 15. The frequency error signal S6 of the frequency comparator circuit 25 is thus transformed into a drive output S11 at a drive amplifier circuit 35. A brake torque of the transmission device 32 is then controlled by the drive output S11 to modify the slippage of the belt 33, thus synchronizing the rotational speed of the output shaft 34 with the reference pulse signal S REF . With the construction illustrated in Figure 2, the capstan motor 14 (Figure 1) can be replaced by the electromagnetic brake type transmission device 32 (Figure 2) as compared with the construction of Figure 1, thereby reducing the size of the apparatus. However, the structure of Figure 2 is still not satisfactory for practical use in a case where the structure must be further miniaturized. US-A- 3,343,353 and JP-A-59-146 406 shows tape systems employing a single drive motor to drive both the capstan and the rotating head. Embodiments of the present invention provide a rotary head recording and reproducing apparatus that can be miniaturized and simplified further as compared with driving systems such as those shown in Figures 1 and 2. (2) First Embodiment In Figure 3, a rotational torque or a turning force applied to the rotary drum 3 by the drum motor 2 is transferred to the capstan 15 by a transmission means 30 formed of gears. The capstan 15 is thus driven at a speed reduced in accordance with the overall gear ratio of the gears to a rotational speed appropriate to that of the rotary drum 3. In this embodiment, the transmission means 30 shown schematically as a dotted line in Figure 3 include, as Figure 4 shows, a motor pinion gear 32′ rotated integrally with the rotary drum 3. The motor pinion gear 32′ engages a capstan gear 35′, rotating integrally with the capstan 15 through relay gears 33′ and 34′ having a predetermined reduction ratio. Further, in this embodiment, the relay gear 34′ engages a take-up reel gear 40 rotating integrally with the take-up reel 11 through relay gears 34X, 36, 37, 38, 39, 39X in that order, thereby taking up the tape 6. A rewind idler gear 41 is interposed between a coupling gear 42 engaging the relay gear 37 in the rewind mode and the reel base of the feed reel 5. A quick-traverse idler gear 43 couples the relay gear 37 and the reel base of the take-up reel 11 during the quick-traverse or fast-forward mode. When the tape cassette 4 is used upside down, a pinch roller 10 instead of the pinch roller 7 comes into contact with the capstan 15, so that the tape 6 can be played in either direction. The phase detection signal S1 (Figure 3) obtained from the pulse generator 22 during recording is supplied to an input terminal REC of a switching circuit 51 of a servo signal processing circuit 50. From there, it passes to a servo signal forming circuit 52, which generates a servo output signal S23. The servo output signal S23 corresponds to a servo phase setting signal S22 derived from a lock phase assigning signal S21. The signal S21 is generated by a drum lock phase assigning circuit 54 and is supplied through a switching input terminal REC of a switching circuit 53 during recording. The servo output signal S23 is transformed into a direct current drive output signal S24 through a drive amplifier circuit 55 and a low-pass filter 56. The drive output signal S24 is supplied to the drum motor 2. Thus in the recording mode, the servo signal processing circuit 50 drives the rotary drum 3 in rotation in a state locked to a phase corresponding to the lock phase assigning signal S21, and also drives the capstan 15 in rotation at a speed dictated by the reduction ratio of the driving gear train and corresponding to the rotational speed of the rotary drum 3. As a result, as Figure 5 shows, a signal supplied by the recording/reproducing circuit 13 of Figure 3 is recorded obliquely on the tape 6 by the magnetic heads 12A and 12B. The magnetic heads 12A and 12B scan in a head scanning direction K2 (Figure 5) obliquely with respect to the tape 6. Recording tracks 57 are formed in abutting relation to each other successively in the tape running direction K1. In this embodiment, track addresses ... n - 1, n, n + 1 ... are assigned to the recording tracks 57 (Figure 5). Each of the recording tracks 57 of the track addresses ... n - 1, n, n + 1 ... is divided into blocks BLK with block addresses ... m - 1, m, m + 1 ... assigned in the head scanning direction K2. Address data indicating the track address n (n = ... n - 1, n, n + 1 ...) and block data indicating the block address m (m = ... m - 1, m, m + 1 ...) are recorded in each block BLK together with information data. Thus when the magnetic heads 12A and 12B scan each block BLK in the reproducing mode, the track address and the block address are supplied to the recording/reproducing circuit 13 as a pick-up signal S26 (Figure 6) together with the information data. As Figure 6 shows, in the recording mode the recording/reproducing circuit 13 supplies a recording data signal S35 obtained from a recording signal processing circuit 13D to the magnetic heads 12A and 12B as the recording signal S25 through a recording amplifier circuit 13E and a head switching circuit 13A. The recording/reproducing circuit 13 supplies the pick-up signal S26 coming from the magnetic heads 12A and 12B in the reproducing mode to a demodulator circuit 63 through the head switching circuit 13A and a reproducing amplifier circuit 13B in that order, and supplies the demodulated data output S27 to an error detection and data separation circuit 64. The error detection and data separation circuit 64 sends the information data S28 including error detection information to a temporary memory 65 for time base correction (TBC) by means of an audio data detection code signal included in the demodulation data output S27. The separation circuit 64 also supplies a write address data signal S29 comprising the track address n and the block address m to the temporary memory 65 through a selector 66. An information data signal S28 is written in the memory address assigned by the track address n and the block address m. Thus when the magnetic heads 12A and 12B supply the pick-up signal S26, every block BLK (Figure 5) is reproduced and stored in the temporary memory 65. A read address data signal S30 is formed by a read address forming circuit 67 and supplied to the temporary memory 65 through the selector 66, and the information data stored in the temporary memory 65 are read from the data of the first block successively at a predetermined data transmission rate at every track address n (n = ... n - 1, n, n + 1 ...). As a result, the temporary memory 65 generates a reproducing output signal S32 comprising information data S28 corrected for time base errors. The data thus read out and corrected are sent as the reproduced output signal S31 through an output circuit 68 comprising a digital/analogue converter circuit (not shown in Figure 6). In this embodiment, since a track servo system is not provided for controlling the capstan 15, the magnetic heads 12A and 12B effectively run, as indicated by a scanning path SCN in Figure 5, according to a scanning system (called a non-tracking system) such as will permit scanning across a plurality of the recording tracks 57 between a running-in point and a breakaway point. (The magnetic heads 12A and 12B make contact with the tape 6 at a running-in-point and scan the tape 6 to a breakaway point, where they leave the tape 6.) If the magnetic heads 12A and 12B scan on the scanning path SCN, then the scan path crosses the recording tracks successively in the order of track addresses ... n + 1, n, n - 1, ..., and scan the blocks BLK in the order of block addresses m = 0, 1 ... m - 1, m, m + 1 ... M - 1, M. Accordingly, the write address data S29 obtained from the error detection and data separation circuit 64 has a content increasing continuously as the track address n and the block address m, and the content of the track address n of the write address data S29 indicates a scanning position while the magnetic heads 12A and 12B scan the tape 6. Thus track address data (comprising an upper bit portion of the demodulation data output S27) indicating the track address n of the write address data S29 is supplied to a track address comparator circuit 69 (Figure 3) from the recording/reproducing circuit 13 as a scanning position detection signal S29X. In addition, track address data corresponding to the read address data S30 supplied by the read address forming circuit 67 in the recording/reproducing circuit 13 (Figure 6) is supplied to a track address comparator circuit 69 as a scanning position reference signal S30X (Figure 3). The track address comparator circuit 69 generates an address difference detection signal S33. The signal S33 indicates the differential addresses between a reference track address assigned by the scanning position reference signal S30X and a detection track address of the recording track scanned concurrently, which is indicated by the scanning position detection signal S29X. The signal S33 is supplied to the servo signal forming circuit 52 by way of a switching input terminal PB of the switching circuit 51 (Figure 3) during playback. A servo output signal S23 corresponding in magnitude to the address difference is supplied by the servo signal forming circuit 52. In the playback mode, an offset position assigning signal S34 of an offset position assigning circuit 70 is supplied to the servo signal forming circuit 52 through an input terminal PB of a switching circuit 53. The servo output S23 thus indicates a head scanning position offset by the offset position assigning signal S34. The magnetic heads 12A and 12B are thus in a servo controlled state to scan the tape 6 as set to a scanning position assigned by the offset position assigning signal S34. In the recording mode of the structure described above, the drum motor 2 (Figure 3) operates to rotate the rotary drum 3 in such a manner that the phase detection signal S1 obtained from the pulse generator 22 coincides in phase with the lock phase assigning signal S21 of the drum lock phase assigning circuit 54, and the capstan 15 is driven in rotation at a predetermined reduction ratio with respect to the rotary drum 3. Thus, the magnetic heads 12A and 12B scan in the head scanning direction K2 at a rotary phase assigned by the look phase assigning signal S21 and also at a predetermined rotational speed, the tape 6 is run at the same time at a speed determined by a gear ratio of the driving gears, and finally the recording tracks 57 are formed on the tape 6. During playback, the address difference detection signal S33 obtained from the recording/reproducing circuit 13 in accordance with the pick-up signal S26 of the magnetic heads 12A and 12B is offset by the offset position assigning signal S34, and the drum motor 2 is in a servo-controlled operating state wherein the magnetic heads 12A and 12B scan the track address position offset by an offset track address indicated by the offset position assigning signal S34. The magnetic heads 12A and 12B are offset to an address indicated by the read address data S30, and the capstan 15 operates so as to interlock with the rotary drum 3 at a rotational speed determined by the reduction gear ratio. If the track address S30X of the read address data S30 of the read address forming circuit 67 (Figure 6) increases, then the magnetic heads 12A and 12B are controlled to scan a track address position displaced by the offset position assigning S34, and thus audio recording data are read out of all the blocks BLK of the recording tracks 57 formed on the tape 6 and can be written in the temporary memory 65. In such state the rotary drum 3 rotates stably at a speed following the scanning position reference signal S30X, and the capstan 15 also rotates stably. Thus, even if the rotary head recording and reproducing apparatus becomes oscillatory as a whole, a track pitch and a scanning pitch will not fluctuate (the speed ratio of the rotary drum 3 and the capstan 15 is constant). Accordingly, as indicated by the scanning path SCN in Figure 5, the magnetic heads 12A and 12B operate to reproduce recording data on the recording tracks 57 while shifting their scanning position sequentially in such a direction as to coincide with the tape running direction K1 and as to maintain a predetermined angle of inclination with respect to the recording tracks 57. With the construction described above, a common driving motor is provided for driving the rotary drum 3 and the capstan 15, and a single servo system suffices to control the driving motor. Therefore, a driving system that is simplified and miniaturized is realizable. Moreover, the recording and reproducing of information data on and from the tape 6 undergoes no deterioration. (3) Concrete Construction of the Embodiment The rotary head recording and reproducing apparatus described above with reference to Figures 3 to 6 may be shown in Figures 7A to 10C. A speed detection signal S40 (Figure 7A) produced by a frequency generator (FG) 81 coupled to a rotating shaft of the rotary drum 3 is supplied to a speed comparison circuit 83 (Figure 7B). The speed comparison circuit 83 generates speed detection data S41 indicating any deviation from a predetermined reference speed and supplies it as speed data S42 to an addition circuit 85 through a speed gain circuit 84. An addition output S43 of the addition circuit 85 is supplied to a digital/pulse width modulator circuit 86. The digital/pulse width modulator circuit 86 modulates the width of a carrier pulse having a predetermined carrier frequency (for example 256 kHz) to a duty ratio corresponding to a digital numeric value indicated by the addition output S43 and supplies it to a drive amplifier circuit 87 (Figure 7A) and a carrier filter 88 as a servo output signal S44. The signal S44 is transformed to a direct current in the carrier filter 88 and supplied to the drum motor 2 as a drive output S45, thereby driving the rotary drum 3 at a predetermined reference speed. The phase detection signal S1 obtained from the pulse generator 22 (Figure 7A) is supplied to a phase comparison circuit 91 (Figure 7B) of a servo signal processing circuit 82. The phase comparison circuit 91 samples a reference phase counting signal S46 obtained from a reference counting circuit 92 according to the phase detection signal S1 and supplies detection phase data S47 indicating the difference between the rotary phase of the rotary drum 3 and the counting phase of the reference counting circuit 92. The phase detection data S47 is supplied to an addition circuit 94 through an input terminal REC of a switching circuit 93 during recording. In the case of this embodiment, the reference counting circuit 92 forms the reference phase counting signal S46 by counting a clock pulse of a clock signal S49 generated by a clock signal generation circuit 90. The lock phase assigning signal S21 generated by the drum lock phase assigning circuit 54 is supplied to the addition circuit 94 through an input terminal REC of a switching circuit 96 during recording. The addition circuit 94 is thus capable of setting a lock phase of the rotary drum 3 by adjusting the detection phase data S47 according to the lock phase assigning signal S21 during recording. As a result, position difference data S48 indicating the phase difference (indicated as a track address) with respect to a reference phase position (namely a scanning position of the magnetic heads 12A and 12B on the tape 6) of the rotary drum 3 is obtained at an output terminal of the addition circuit 94. The position difference data S48 is supplied to the addition circuit 85 as position data S50 through a phase gain circuit 97 and an input terminal REC of a switching circuit 98 during recording. In the case of this embodiment the reference phase counting circuit 92 generates a rotary phase when the rotary drum 3 rotates at a reference speed as the reference phase counting signal S46. This is represented as numeric data by counting the clock signal S49 generated by the clock signal generation circuit 90 during the period corresponding to the time during which the rotary drum 3 rotates one turn at the reference speed. The phase comparison circuit 91 samples a value of the reference phase counting signal S46 according to the phase detection signal S1 obtained from the pulse generator 22 (Figure 7A) when the rotary drum 3 comes to a predetermined rotation position, thereby transmitting the detection phase data S47 indicating any difference between the rotary phase of the rotary drum 3 and the reference phase counting signal S46. The drum lock phase assigning circuit 54 assigns one of the count values included in the counting width of the reference phase counting signal S46 as a drum lock phase, thus obtaining data indicating any deviation between the rotary phase of the rotary drum 3 during recording the drum lock phase. Any such difference is locked as the position difference data S48. As a result, in a state where the rotary drum 3 is rotated and driven at a rotational speed corresponding to the speed data S43 obtained from the speed detection circuit 83, the drum motor 2 drives the rotary drum 3 so as to obtain a servo operating state where the value of the phase data S50 becomes "0". Thus the rotary phase of the rotary drum 3 will be locked to a phase shifted in accordance with the track address of the lock phase assigning signal S21. As Figure 8 shows, the recording signal processing circuit 13D of the recording/reproducing circuit 13 receives a recording audio signal S IN in an encoder 112 through an analogue/digital converter circuit 111, and encodes it as synchronizing with track address data DTA, block address data DBA and word address data DWA generated in an address generation circuit 113. The address generation circuit 113 is timed by the clock signal S49. In an address addition circuit 114, a track address TA and a block address TB are added to audio data D REC generated in the encoder 112. The track address TA and block address TB are obtained from the track address data DTA and the block address data DBA. A synchronizing signal SYNC and an error correction code CRCC are added in a synchronizing signal/error correction code (SYNC/CRCC) addition circuit 115 subsequently thereto. The circuit 115 supplies a track data output D TR to a modulator circuit 115, and recording outputs S REC thus obtained from the modulator circuit 116 are supplied to the magnetic heads 12A and 12B alternately as the recording signal S25 and S26 from the recording signal processing circuit 13D through the recording amplifier circuit 13E and the head switching circuit 13A (Figure 7A). Thus the track data D TR are recorded successively on the recording tracks 57 (Figure 5) by the magnetic heads 12A and 12B. In the case of this embodiment the track data D TR comprises a predetermined number of block data BL0, BL1,... BLM successively, as shown in Figure 10A, on every recording track 57. Each of the block data BLm (m=0, 1... M) comprises, as Figure 10B shows, successive synchronizing data SYNC, address data AD, parity check data PC, audio data DATA and error correction code data CRCC. In the case of this embodiment the synchronizing data SYNC and the address data AD comprise data for one word each, the parity check data PC comprise data PC1 to PC4 for four words for detecting errors of the synchronizing data SYNC and the address data AC, the audio data DATA comprise data for sixteen words, and the error correction code data CRCC comprise data CRCC1 and CRCC2 for two words for correcting errors of the synchronizing data SYNC to the audio data DATA. The address data AD added to the block data BLm (m=0 to M) comprises, as Figure 10C shows, track address data TA indicating the track address n of the recording tracks 57 (Figure 5) on which the block data BLm are recorded, and block address data BA indicating the block address m of the block data BLm. In this embodiment, the block address data BA comprises word data BA0 to BA6 for seven words, and the track address data TA comprise word data TA0 to TA5 for six words. Thus, when the block data BLm are picked up from the magnetic heads 12A and 12B scanning blocks BLK on the recording tracks 57 in the reproducing mode, positions scanned by the magnetic heads 12A and 12B are ensured by the track address data TA and the block address data BA. Figure 9 shows details of the reproducing signal processing circuit of Figure 7A. The reproduced input S PB from the reproducing amplifier circuit 13B passes through an equalizer circuit 121 and a phase locked loop (PLL) circuit 122. The latter separates it into a data signal S51 and a clock signal S52, both of which are demodulated by a demodulation unit circuit 123. The circuits 121 to 123 together form the demodulator circuit 63. The demodulation unit circuit 123 supplies reproducing track data S53, which is the track data D TR shown in Figure 10A, to a data separation circuit 124 together with a reproducing clock signal S54 corresponding to the clock signal S52. The data separation circuit 124 separates the parity check data PC and the error correction code data CRCC included in each data block PLm (m=0 to M) arriving as the reproduced track data S53 and supplies them to an error check circuit 125 for error detection and correction processing of the reproduced track data S53. The circuit 124 also transmits an error flag EFG to a time base correction memory 126, as occasion demands. Thus the data separation circuit 124 supplies the audio data DATA included in the reproduced track data S53 to the time base correction memory 126, and writes it in the time base correction memory 126 according to an address signal S55 obtained from a switching circuit 127. In this embodiment the data separation circuit 124 generates a word clock signal ECK whenever a data word of the data block BLm arrives as the reproducing track data S53, supplies it to a word address counter 128 to form a word address WA to provide to the switching circuit 127, separates the block address data BA and the track address data TA from the address data AD and supplies them to the switching circuit 127. The switching circuit 127 supplies the word address WA, the block address BA and the track address TA to the time base correction memory 126 as the address signal S55 in the writing mode, thereby writing the audio data DATA in a memory area assigned by the address signal S55. The audio data DATA thus written in the time base correction memory 126 is read when a read word address RWA, a read block address RBA and a read track address RTA generated in a read address forming circuit 129 are supplied to the time base correction memory 126 through the switching circuit 127 as the address signal S55. The circuit 126 supplies an output to a decoder 130 as a read audio data WDATA and a read error flag WEFG. In order to correct errors by means of the read error flag WEFG as occasion demands, the decoder 130 restores reproduced audio data S57 according to the read audio data WDATA, and then sends it as a reproduced audio signal S OUT through a digital/analogue converter circuit 131. In this embodiment, the clock signal S49 of the clock signal generation circuit 90 (Figure 7B) and a reference synchronizing signal S60 obtained from the reference counting circuit 92 are received by the read address forming circuit 129 (Figure 9) as reference signals for obtaining the reproduced audio signal S OUT . In the latter signal, the time base is corrected through the storage of data in the time base correction memory 126. In accordance with the clock signal S49 and reference synchronizing signal S60 corresponding to the synchronizing data SYNC (Figure 10B) of each data block BLm (Figure 10A), the read word address RWA, the read block address RBA and the read track address RTA are generated by the read address forming circuit 129. A timing generation circuit 132 receives the clock signal S49 and generates a timing signal S58, which is supplied to the switching circuit 127, the time base correction memory 126, the decoder 130 and the analogue/digital converter circuit 131. The reproduced audio signal S OUT corresponding to the read audio data WDATA and the read error flag WEFG of the time base correction memory 126 is formed in accordance with the reference clock signal. In addition, a track address comparator circuit 140 in the reproduced signal processing circuit 13C (Figure 9) compares the track address TA separated by the data separation circuit 124 and the read track address RTA formed in the read address forming circuit 129. The track address comparator circuit 140 generates a detection address signal S61 indicating the deviation between the two input signals and sends the signal S61 through a bus interface 141 of the reproducing signal processing circuit 13C, which generates a corresponding output signal S62. The signal S62 is provided to the addition circuit 94 (Figure 7B) through a reproducing input terminal PB of the switching circuit 93 by way of a bus interface 142 of the servo signal processing circuit 82. An offset position signal S63 (Figure 7B) generated by an offset position assigning circuit 143 is supplied to the addition circuit 94 through an input terminal PB of the switching circuit 96 during reproducing. The position difference data S48 indicating a track address which is the sum of the offset track address indicated by the offset position signal S63 and the track address indicated by the position difference detection signal S62 is obtainable at an output terminal of the addition circuit 94. The drum motor 2 (Figure 7A) is driven in accordance with the position difference data S48 (Figure 7B) through the phase gain circuit 97, an address difference smoothing circuit 99, the addition circuit 85, the digital/pulse width modulator circuit 86, the drive amplifier circuit 87 (Figure 7A) and the carrier filter 88, which produces the signal S45. The rotary drum 3 is thus driven in a servo operating state wherein the position difference data S48 becomes "0". As a result, the rotational position of the rotary drum 3 (namely the scanning position of the magnetic heads 12A and 12B with respect to the tape 6) is offset in that the read track address RTA is modified by the track address of the offset position signal S63. In the construction of Figures 7A to 10C, the switching circuits 93, 96 and 98 of the servo signal processing circuit 82 are kept engaged with the respective input terminals PB during reproducing. Therefore, the rotary drum 3 is subjected to a servo control substantially in accordance with the track address data TA (Figure 10C) of the address data AD (Figure 10B) included in the pick-up signal S26 obtained from the magnetic heads 12A and 12B. The scanning position of the magnetic heads 12A and 12B on the tape 6 is set by the offset position signal S63 supplied by the offset position assigning circuit 143. That is, the pick-up signal S26 is taken into a reproducing signal processing circuit 13c through the head switching circuit 13A and the reproducing amplifier circuit 13B of the recording/reproducing circuit 13. Therefore, when the audio data DATA are written in the time base correction memory 126 from the data separation circuit 124 (Figure 9) and also read by the read address forming circuit 129, the track address TA separated in the data separation circuit 124 is compared with the read track address RTA obtained from the read address forming circuit 129 in the track address comparator circuit 140. The detection address signal S61 indicating the deviation is supplied to the servo signal processing circuit 82 (Figure 7B) as the position difference detection signal S62. The servo signal processing circuit 82 is therefore controlled to a servo operating state where the position difference data S48 becomes "0". If the tape cassette 4 recorded by means of a plurality of plug-compatible machines comprising the rotary head recording and reproducing apparatus constructed as shown in Figures 7A and 7B is reproduced interchangeably, then there may be a case where the angle of the scanning path of the rotary magnetic heads with respect to the recording tape in each plug-compatible machine does not coincide with the recording track. This can result because of a difference in structure of the tape running system. In that case, a rotary magnetic head 12A (or 12B) scans across the recording track 57 slantwise as shown in Figure 11. That is, when the angle of the scanning path SCN1 of the magnetic head 2A (or 2B) coincides with the recording path of the recording track 57, the magnetic head 2A (or 2B) scans the nth recording track 57 whereat the azimuth angle coincides. The magnetic head 2A (or 2B) thus picks up recording data from the nth recording track 57. When the scanning angle of the magnetic head 2A (or 2B) does not coincide with a recording path of the recording track, the magnetic head 12A (or 12B) scans the nth recording track 57 slantwise, and if the deviation of the scanning angle is large enough, the magnetic head 2A (or 2B) also scans the neighbouring recording tracks where the azimuth angle coincides, namely the (n+2)th and the (n-2)th recording tracks 57, as indicated by scanning paths SCN2 and SCN3 in Figure 11. Thus the magnetic head 12A (or 12B) picks up recording data not only from the nth recording track 57 but also at least from the (n-1)th and the (n+1)th recording tracks 57 on opposite sides of the nth track. In a scanning state wherein, for example, the offset phase signal S63 of the offset position assigning circuit 143 (Figure 7B) has been set to an offset-free state, the following operation takes place. In a first scanning state in which the scanning path SCN1 is followed, the read address forming circuit 129 (Figure 9) sends the read track address RTA for reading audio data of the recording tracks 57 of the reference track addresses n - 1, n, n + 1, as shown in Figure 12A, from the time base correction memory 126 (Figure 9) in accordance with the reference synchronizing signal S60 of the reference counting circuit 92 (Figure 7B). The track address TA separated from the data separation circuit 124 (Figure 9) in accordance with the pick-up signal S26 of the magnetic head 12A (or 12B) of the rotary drum 3 is then ready for the magnetic head 12A (or 12B) to scan the track of address n during the whole scanning period. When the read track address RTA assigns the track addresses n - 1, n, n + 1 successively (Figure 12A), it operates to provide the track address TA obtained from the identical track addresses n - 1, n, n + 1 to the track address comparator circuit 140 (Figure 9), as shown in Figure 12B. Accordingly, an "0" level signal as an address difference between the read track address RT and the track address TA is appropriated, as shown in Figure 12C, to the position difference detection signal S62 supplied to the switching circuit 93 of the servo signal processing circuit 82 (Figure 7B) by way of the bus interfaces 141 and 142 and in accordance with the detection address signal S61 of the track address comparator circuit 140. Thus when the "0" level position difference detection signal S62 is supplied to the servo signal processing circuit 82, a value of the position data S50 to be added to the speed data S42 at the addition circuit 85 is "0", and the drum motor 2 causes the rotary drum 3 to rotate at a speed such as to make the tape 62 draw the first scanning path SCN1. However, in such an operating state, if the rotational position of the rotary drum 3 is shifted, the track address TA obtained from a pick-up signal S24 of the magnetic heads 12A and 12B when the read track address RTA (Figure 12A) assigns the track addresses n - 1, n, n + 1 is shifted towards the preceding or following track. Hence the position difference detection signal S62 is shifted from the "0" level state of Figure 12C to the "+1" (positive) signal level or the "-1" (negative) signal level. In this case the position data S50 corresponding to the shift added to the speed data S42 in the addition circuit 85 (and therefore the driving speed of the drum motor 2) is modified in the direction removing the shift, and the scanning position of the magnetic head 12A (or 12B) is brought back to the track addresses n-1, n, n+1 assigned by the read track RTA. When the tape cassette 4 scanning thus on the first scanning path SCN1 is installed, the rotary drum 3 is controlled to a position servo state where the magnetic heads 12A and 12B are made to scan successively on the same recording track. When the magnetic heads 12A and 12B trace the scanning path SCN2 across the recording track slantwise, as shown in Figure 11, so that the read track address RTA of the read address forming circuit 129 assigns the track addresses n-1, n, n+1 in that order as shown in Figures 13A, 13B and 13C corresponding to Figures 12A, 12B and 12C, the track addresses TA obtained fro the data separation circuit 124 in accordance with the pick-up signal of the magnetic head 12A (or 12B) are (n-2, n-1, n), (n-1, n, n+1), (n, n+1, n+2) as shown in Figure 13B. Thus when the scanning path SCN2 crosses the track addresses n - 1, n, n + 1, the azimuth angle scans the identical neighbouring recording tracks on the running-in side and breakaway side of the magnetic head 12A (or 12B). In this case the position difference detection signal S62 supplied to the switching circuit 93 of the servo signal processing circuit 82 in accordance with the detection address signal S61 indicating an address deviation between the read track address RTA and the track address TA in the track address comparator circuit 140 becomes "0", as shown in Figure 13C, when the track address TA is equal to the read track address RTA. The timing is such that the track address TA becomes unequal to the read track address RTA before and after it is equal thereto. A negative deviation signal DN1 and a positive deviation signal DP1 indicating the address deviation are generated. When such position difference detection signal S62 is supplied to the addition circuit 85 as the position data S50, the servo output signal S44 for averaging the deviation signals DN1 and DP1 is obtained through a system comprising the digital/pulse width modulator circuit 86, the drive amplifier circuit 87 and the carrier filter 88. The drum motor 2 is thus in a driving state such as not to modify the rotational speed (which is assumed to be free from deviation) when the deviation signals DN1 and DP1 are equal to each other. If scanning positions of the magnetic heads 12A and 12B are shifted, the times for the rotary magnetic heads 12A and 12B to scan the adjacent recording tracks become unequal, and thus the times for the position difference detection signal S62 to generate the deviatlon signals DN1 and DP1 become unequal to each other. In this case the drum motor 2 has its rotational speed controlled in such a direction that the deviation signals DN1 and DP1 are equal to each other, and finally is driven in a servo control state wherein a mean value of the position difference detection signal S62 becomes "0". Sometimes the magnetic heads 12A and 12B will trace a scanning path running in from the succeeding recording track and crossing the preceding recording track as indicated by a scanning path SCN3 in Figure 11. In this case, the read track address RTA (Figure 14A) of the read address forming circuit 129 assigns the track addresses n-1, n, n+1, and the track address TA separated from the data separation circuit 124 in accordance with the pick-up signal S24 of the magnetic heads 12A and 12B generates track addresses indicating that the adjacent recording tracks are scanned before and after the identical track addresses n-1, n, n+1. As Figure 14C shows, the position difference detection signal S62 corresponding thereto is such that deviation signals DP2 and DN2 equal in duration to each other are generated as in the case of the deviation signals DN1, DP1 of Figure 13C except that curvatures of the signal level are reversed. In this case, when the phase data S50 corresponding to the phase difference detection signal S62 is supplied to the addition circuit 85, the drum motor 2 has its rotational speed controlled so as to make the durations of the deviation signals DP2 and DN2 equal to each other. If for any reason the scanning phase of the magnetic heads 12A and 12B is shifted from such servo state to the recording track on a preceding side or to the recording track on a succeeding side, then an unbalanced position difference detection signal S62, in which the duration of the deviation signal DP2 or DN2 becomes longer in accordance with the magnitude of the shift, is generated, and the position data S50 corresponding thereto is supplied to the addition circuit 85. The drum motor 2 thus corrects its rotational position in such a direction as to remove the imbalance. Thus in the case of the scanning path SCN3, scanning positions of the magnetic heads 12A and 12B can simply be subjected to a servo control. (4) Other Embodiments 1. In the embodiment described in detail above, the construction is such that the address signal indicating a scanning position of the magnetic heads 12A and 12B is obtainable from recording the track addresses and the block addresses on the recording tracks 57 (Figure 5) together with the information data comprising blocked digital data. However, the track addresses and the block addresses comprising a digital signal each may be recorded instead together with an analogue information signal. The recording track 57 will then be arranged in blocks BLK, and the address signal is ready for picking up from each block. 2. In the embodiment described in detail above, a digital signal is used as the address signal. However, a similar effect can be obtained by recording a control signal (or so-called CTL signal), a pilot signal and the like along the recording track 57 instead of a digital address signal, and subjecting the driving motor to a servo control using the CTL and pilot signals, etc. as an address signal during reproducing. 3. In the embodiment described in detail above, the rotary drum 3 is driven by the drum motor 2 (Figure 3), and the driving force is transferred to the capstan 15 through the transmission means 30. However, the driving system is not necessarily limited thereto. For example, a capstan motor may be employed and the driving force of the capstan motor may be transferred to the rotary drum 3, or a common single driving motor may be provided for the rotary drum 3 and the capstan 15, and the rotary drum 3 and the capstan 15 may be driven by the common driving motor through a transmission system and so forth. In short, by using a single driving motor to drive the rotary drum 3 and the capstan 15 at a predetermined speed ratio, the running speed of the tape 6 during reproducing will be controlled so as to lock the scanning track address of the rotary magnetic head with respect to the reference address position. 4. In the embodiment described in detail above, the phase detection signal S1 during recording is obtained from the pulse generator 22 provided at the rotary drum 3. However, the pulse generator 22 is not necessarily positioned at the rotary drum 3. The phase detection signal S1 may be taken instead from the driving system for the rotary drum 3 and the capstan 15.

Claims: A rotary head tape recording and reproducing apparatus for recording or reproducing an information signal including address data on or from recording tracks formed on a magnetic tape (6) across a longitudinal direction of said magnetic tape (6), the apparatus comprising: rotary head means (12A, 12B); head drum means (3) mounting the rotary head means (12A, 12B) and supporting a magnetic tape (6) wound around the head drum means (3) along a predetermined wrap arc, the rotary head means (12A, 12B) recording or reproducing the information signal on or from the magnetic tape (6); capstan means (15) for driving the magnetic tape (6); transmission means (30) connected to the head drum means (3) and the capstan means (15); common motor means (2) for driving the transmission means (30), the head drum means (3) and the capstan means (15), at least the head drum means (3) and the capstan means (15) being driven in rotation; characterised by reference means (22, 26) for generating first and second reference signals; comparison means (69) for comparing the first reference signal with a first output signal representing a rotational state of the rotary head (12A, 12B) to produce a first comparison signal and for comparing the second reference signal with a second output signal representing address data reproduced from the magnetic tape (6) by the rotary head means (12A, 12B) to produce a second comparison signal; and servo control means (52) operative in a recording mode for controlling the common motor means (2) in accordance with the first comparison signal and in a reproducing mode for controlling the common motor means (2) in accordance with the second comparison signal. Apparatus according to claim 1 wherein the first output signal is a phase signal generated in accordance with the rotation of the rotary head means (12A, 12B). Apparatus according to claim 2 further comprising a pulse generator (22) and wherein the first output signal is a pulse signal generated by the pulse generator (22). Apparatus according to claim 1 wherein the first reference signal comprises a reference phase signal. Apparatus according to claim 1 wherein the first reference signal comprises a reference clock signal. Apparatus according to claim 1 wherein the second output signal comprises a reproduced block address data signal. Apparatus according to claim 1 wherein the second reference signal comprises a reference address data signal. Apparatus according to claim 6 further comprising memory means (65) for temporarily memorizing an information signal reproduced by the rotary head means (12A, 12B) and wherein the second reference signal comprises a read address data signal for reading the information signal. Apparatus according to claim 1 further comprising means (84) for generating a third reference signal and adder means (94) for the first comparison signal and the third reference signal to produce a first addition signal and wherein, in a recording mode, the servo control means (52) controls the common motor means (2) in accordance with the first addition signal. Apparatus according to claim 9 further comprising a drum lock phase assigning circuit (54) and wherein the third reference signal comprises a drum lock phase assigning signal produced by the drum lock phase assigning circuit (54). Apparatus according to claim 1 further comprising means (76, 143) for generating a fourth reference signal and adder means (94) for adding the second comparison signal and the fourth reference signal to produce a second addition signal and wherein, in a reproducing mode, the servo control means (52) controls the common motor means (2) in accordance with the second addition signal. Apparatus according to claim 11 further comprising an offset position assigning circuit (70, 143) and wherein said fourth reference signal comprises offset position assigning address data generated by the offset position assigning circuit (70, 143). Apparatus according to claim 1 wherein the servo control means (52) comprises a speed comparison circuit that generates a third comparison signal which is a function of the rotation of the rotary head means (12A, 12B), and the servo control (52) controls the common motor means by a third addition signal which is the sum of the first or second comparison signal and the third comparison signal. Apparatus according to claim 1 wherein the common motor means (2) comprises a drum motor (2) integrated with the head drum means (3). Apparatus according to claim 1 wherein the common motor means (2) comprises a capstan motor integrated with the capstan means (15). Apparatus according to claim 1 wherein the transmission means (30) comprises a rotational driving gear mechanism. Apparatus according to claim 1 wherein the common motor means (2) also drives a take-up reel base which winds the magnetic tape (6).

Inventors: TANAKA MASATO C O PATENT DIVIS, TANAKA, MASATO, C/O PATENT DIVISION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1990
Main classification: G11B15
IPC codes: G11B15