METHOD AND APPARATUS FOR A MAGNETIC RECORDING/REPRODUCING

Abstract: A helical scan type magnetic tape recording/reproducing apparatus for recording/reproducing information, for exam­ ple, a large amount of time-compressed audio PCM signals on a plurality of information tracks disposed in parallel to the direction of the tape running. Each of the time-compressed audio PCM signals are recorded with one of four frequencies of a pilot signal on a selected information track, and each of the time-compressed audio PCM signals recorded on the information tracks can be selectively reproduced from the corresponding information track. The apparatus includes a circuit for generating a plurality of track indicating pulses which respectively correspond to the information tracks and are phase-locked to the rotation of the rotating heads, and a circuit for selecting one of the track indicating pulses, which is supplied to control time compressing/expanding of an audio signal.

Description: This invention relates to a helical scan type information recording/ reproducing apparatus, especially to a magnetic tape recording/ reproducing apparatus for recording/reproducing a large amount of information on a magnetic tape. Some prior art examples of a helical scan type information recording/ reproducing apparatus are a consumer-use VTR (video tape recorder) represented by the VHS format, a tape pattern of which is shown in Figure 1, and another consumer-use VTR, known as an 8 mm-Video, a tape pattern of which is shown in Figure 2. Examples of such apparatus may be seen from the Taniguichi et al U.S. Patent No. 4,303,950 and the Furumoto et al U.S. Patent No. 4,390,906. In Figure 1 a video tape 1 is provided with a video track 2 on which a video signal is recorded, a control track 3 on which a control signal is recorded, and an audio track 4 on which an audio signal is recorded. The tracing direction of a rotating head is indicated by the arrow 5 and the running direction of the video tape 1 is indicated by the arrow 6. The portions ϑ₁, ϑ₂ and ϑ₃, respectively, of the video track denote winding angles of the video tape wound around a rotating cylinder. The angles ϑ₁ and ϑ₃ are nearly equal to 5° and the angle ϑ₂ is nearly equal to 180°. The angle ϑ₂ corresponds to the duration of recording of the video signal, and the angles ϑ₁ and ϑ₃ correspond to the duration of the margin for maintaining an exchangeability of the two rotating heads. In Figure 2 video may be recorded on the track segment 2, while a track segment 7 is utilized for recording a time-compressed audio signal. The numeral 8 designates a first option track, and the numeral 9 designates a second option track. The time-compressed audio signal is produced by converting an audio signs to a PCM signal and compressing the PCM signal to about one-sixth time scale. The portions ϑ₁, ϑ₂, ϑ₃ and ϑ₄, respectively, of the video track denote winding angles of the video tape as it is wound around a rotating cylinder. The angles ϑ₁ and ϑ₃ are nearly equal to 5°. The angle ϑ₂ is nearly equal to 180°, and the angle ϑ₄ is nearly equal to 30°. The angle ϑ₄ responds to the duration of recording of the time-compressed audio signal. As can be seen from the above explanation of the prior art, there are only one or two kinds of information which can be recorded on one slant track with the prior art apparatus. Accordingly, the utilization range of the video tape with the prior art apparatus is very narrow. Another prior art example is given in the European parent application of SONY Corporation published under the number 0 085 578 on August 10, 1983. This prior art discloses a helical scan type recording/reproducing apparatus for recording an information signal comprising at least an analog audio signal in a plurality of successive slant tracks on a magnetic tape or for reproducing it therefrom. The apparatus includes a PCM processing circuit for converting an analog audio signal into a PCM audio signal, a video signal processing circuit for processing a video signal to produce an output video signal, a rotary magnetic head assembly for recording the output video signal and the PCM audio signal in the plurality of successive slant tracks on the tape , a switch assembly for supplying the output video signal and the PCM audio signal to the rotary magnetic head assembly and a control circuit for controlling the switch assembly to supply the output video signal and the PCM audio signal to the rotary magnetic head assembly during a video use mode so that the rotary magnetic head assembly records the output video signal in a main section of each track and to supply only the PCM audio signal to the rotary magnetic head assembly during an audio use mode so that the rotary magnetic head assembly records the PCM audio signal in different segments of the main section and overscan section of each slant track, the consecutive segments forming a track in the direction of the tape running. There is no defection of a tracking error signal in order to control the tape running It is an object of the present invention to provide a helical scan type magnetic recording/reproducing method and apparatus, which is able to record/reproduce a large amount of information on one slant track in order to enlarge the utilization range of the tape. Firstly, in accordance with the present invention, each slant track is divided into N segments in the head scanning direction. Here, the number N is more than 3. That is, the tape is divided into N information tracks which are disposed in parallel to the direction of the tape running. Each of a number of different information items may be independently recorded on each of the N information tracks, or the different information items may be sequentially recorded on the N information tracks along each slant track. One of the different information items can be recorded on the information track as voluntarily selected by the operator. Also, the information item can be reproduced from an information track voluntarily selected by the operator. The present invention provides a helical scan type magnetic recording/reproducing apparatus including means for selecting one of the N information tracks during the recording mode and the reproducing mode. The selecting means comprises a pulse generator for generating a number of track indicating pulses which are phase locked to the rotation of the rotating heads and a data selector connected to the pulse generator for selecting one of the track indicating pulses. The selected track indicating pulse is supplied to an information recording/ reproducing processor in order to determine the recording/reproducing timing of the information. Figure 1 is a schematic diagram of a tape pattern of the type used in the prior art; Figure 2 is a schematic diagram of another tape pattern of the type used in the prior art; Figure 3 is a schematic diagram of an embodiment of a tape pattern of the present invention; Figure 4 is a schematic diagram of another embodiment of a tape pattern of the present invention; Figure 5 is a block diagram of an embodiment of a magnetic recording apparatus of the present invention; Figure 6 is a schematic diagram of waveforms of the parts shown in Figure 5; Figure 7 is a block diagram of an embodiment of an audio signal recording processor shown in Figure 5; Figure 7A is a schematic diagram of the digital processor which forms part of the audio signal recording processor shown in Figure 7; Figure 7B is a schematic diagram of the pulse delay circuit which forms part of the audio signal recording processor shown in Figure 7; Figure 8 is a block diagram of an embodiment of a recording amplifying circuit shown in Figure 5; Figure 9 is a schematic diagram of a third embodiment of the tape pattern of this invention; Figure 10 is a schematic diagram of a fourth embodiment of the tape pattern of the present invention; Figure 11 is a block diagram of an embodiment of the essential part of the apparatus for recording the tape pattern shown in Figure 10; Figure 12 is a block diagram of an embodiment of a magnetic reproducing apparatus of the present invention; Figure 13 is a schematic diagram of waveforms of signals appearing at various points in the apparatus shown in Figure 12; Figure 14, 15 and 16, respectively, are block diagrams of other embodiments of the magnetic reproducing apparatus of the present invention; Figures 17, 18, 19 and 20, respectively, are tables for indicating the states of four switches shown in Figures 12, 13, 14 and 15; Figure 21 is a block diagram of an embodiment of a reproducing amplifier circuit shown in Figure 12; Figure 22 is a schematic circuit diagram of an embodiment of a sample and hold circuit shown in Figure 12; Figure 23 is a block diagram of an embodiment of an audio signal reproducing processor shown in Figure 12; Figures 24, 25A and 25B, respectively, are schematic diagrams for explaining an editing system of the present invention; Figure 26 is a flow chart of an embodiment of the editing system of the present invention; and Figure 27 is a block diagram of the embodiment for executing the flow chart shown in Figure 26. Figure 3 shows an example of a tape pattern recorded by the present invention, which is applied to the video tape recorder of the 8 mm Video tape. In Figure 3 each slant track is divided into seven segments 10 - 16 to provide seven information tracks (or channels) A - G. That is, the number N described above is equal to 7. In the tape pattern of Figure 3, the tape is wound around 220° of the rotating cylinder. The information tracks A and G are respectively wound around 35° thereof, and the information tracks B. C, D, E and F are respectively wound around 30° thereof. Figure 4 shows a specific example of the tape pattern shown in Figure 3; however, in this example, only one time-compressed audio PCM signal is recorded on the information track A selected from the information tracks A - G, and the recorded signal contains a plurality of track segments (A₁ ... A₇ ...). The apparatus of the present invention shown in Figure 5 is explained hereinafter, with reference to the tape patterns shown in Figures 3 and 4. In Figure 5, the numerals 22a and 22b denote input terminals from which a 2-channel (stereo) audio signal is applied to an audio signal recording processor 21, The audio signal recording processor 21 converts the audio signal into a PCM signal and compresses the audio PCM signal on the time scale. The compressed audio PCM signal is supplied to a recording amplifier circuit 20, in which the compressed audio PCM signal is mixed with a pilot signal P from a pilot signal generator 28. The output signals Ni or Oi of the recording amplifier circuit 20 are respectively supplied to the rotating heads 23a and 23b of the recording apparatus. The recording amplifying circuit 20 will be explained later in detail with reference to Figure 8. The rotating heads 23a and 23b are attached to the rotating cylinder 23 which is driven by the cylinder motor 26. The numerals 24a and 24b denote two magnets attached to the rotating cylinder 23 at diametrically-opposite points, and the numeral 25 designates a pick-up head. The pick-up head 25 produces a series of pulses H, as shown in Figure 6. In Figure 5, the magnet 24a, which is positioned a small distance ahead of the rotating head 23a in the rotating direction, produces a series of positive going pulses, and the magnet 24b, which is positioned a small distance ahead of the rotating head 23b in the rotating direction, produces a series of negative going pulses. The pulses H from the pick-up head 25 are shaped by a pulse generator 27, which may be provided in the form of a delay circuit, a wave-shaping circuit, etc., and produces output pulses I and Io. The signal level of the output pulse I is related to the rotating phase or position of the heads 23a and 23b. In Figure 5, when the head 23a is tracing on the information tracks B-G, the level of the output pulse I is high, and when the head 23b is tracking on the information track B-G, the level of the output pulse I is low. The output pulse I is supplied from the pulse generator 27 to the pilot signal generator 28. The pilot signal generator 28 sequentially generates a pilot signal P having frequencies of f₁, f₂, f₃ or f₄ in response to the level of the output pulse I. In case the level of the output pulse I is high, the frequency of the pilot signal P Is f₁ or f₃; and, on the other hand, when the level of the output pulse I is low, the frequency of the pilot signal P is f₂ or f₄, as seen in Figure 6, for example. Thus, the information tracks B-G for each slant track will be modulated at a different pilot frequency, as will be explained hereinafter. Responding to each change of the high and low levels, the pilot signal generator 28 varies the frequencies of the pilot signal P as indicated below. For example, the frequencies of the pilot signal P may be selected as follows: Next, a method for synchronizing the phase of the cylinder motor 26, that is, the rotation of the rotating heads 23a and 23b, with the positions of the information tracks is explained. The numeral 30 designates a phase detector that compares the output pulse Io from the pulse generator 27 with an output signal from a monostable multivibrator 33. The output pulse Io, which is not shown in Figure 6, has the same frequency as the output pulse I, but has a different phase from that of the output pulse I. A switch denoted by the numeral 31 is connected to the input terminal of the monostable multivibrator 33. The switch 31 selects either a vertical sync pulse J from a vertical sync pulse separator 32 or a pulse signal M from a delay circuit 35. For example, when the apparatus records the compressed audio PCM signal on the information track A, as shown in Figure 4, the switch 31 selects the pulse signal M, which is derived from an output pulse of a cyrstal oscillator 39 via dividers 40, 38 and 34. In response to the input pulse K, the divider 35 produces parallel output pulses L₁ - L₆, certain ones of which are shown in Figure 6. The parallel output pulses L₁ - L₆ are used for track indicating pulses Also, the output pulse L₁ is delayed by the delay circuit 35 and becomes the pulse signal M. The turning of the pulse signal M is compared with the output pulse Io in the phase detector 30. The monostable multivibrator 33 is provided to convert the vertical sync pulse J, which is 60 Hz, to a frame pulse of 30 Hz. However, the monostable multivibrator 33 has no influence on the pulse signal M, which is already 30 Hz. The output signal of the phase detector 30 is amplified by an amplifier 29 and controls the rotating phase of the cylinder motor 26. As a result, the rotation of the rotating heads 23a and 23b is phase locked to the track indicating pulses L₁ - L₆. The track indicating pulses L₁ - L₆ are also supplied to a data selector 36, which has an input terminal 37 for receiving a track select signal. One of the track indicating pulses L₁ - L₆ selected by the data selector 36 is supplied to the control terminal of the audio signal recording processor 21 via a switch 48. When the compressed audio PCM signal is to be recorded on the information track A, the data selector 36 selects the track indicating pulse L₁ in response to the track select signal applied to terminal 37. The numeral 45 denotes a capstan motor. In order to maintain the speed of the tape 1 constant, a phase detector 43 is used to control the speed of the capstan motor 45. One of the input signals to the phase detector 43 comes from the crystal oscillator 39. In this regard, the output pulses of the divider 40 is further divided by a divider 41 and supplied to the phase detector 43. A frequency generator 46, which is attached to the capstan motor 45, and a pick-up head 47 form a generator for a pulse signal, which is applied to a divider 42. The output pulse of the divider 42 is supplied to a phase detector 43. A phase error signal from the phase detector 43 is amplified by a motor driving amplifier 44 and drives the capstan motor 45. The terminals (N) of the switches 31 and 48 are used in the apparatus to record the tape pattern shown in Figure 2. The switches 31 and 48 are controlled by a manual labor. The numeral 18 denotes a video signal recording processor, and the numeral 17 denotes an input terminal which receives the video signal. The video signal recording processor 18 converts the chrominance signal of the video signal into a low frequency range signal and the luminance signal into an FM signal. In the case where the video signal and the compressed audio PCM signal are recorded as shown in Figure 2, the vertical synchronous pulse J is supplied to the monostable multivibrator 33 via the switch 31. The monostable multivibrator 33 produces the frame pulse, which is compared with the output pulse Io in the phase detector 30. In this case, the audio is compressed and recorded on the information track A. Referring to Figure 6, Q designates a time axis. As the time varies from period (a) to period (g), the head 23a traces the information tracks A - F, as shown in Figure 3. In the middle of the period (g), the head 23b begins to trace the information track A. Both of the heads 23a and 23b track simultaneously on the tape during at least part of the periods (g), (h) and (i). In the same manner, both of them trace on the tape during at least part of the periods (a), (b) and (c), and (m), (n) and (o). When the head 23a is tracing on the information track A, the head 23b traces on the information tracks F and G. This is due to the fact that the tape is wound on the cylinder for more than 180°, as already described. It is desirable that the pilot signal generator 28 is simple, so that when both of the heads 23a and 23b simultaneously record, the frequency of the pilot signal does not vary. Next, the timing for compressing the audio PCM signal will be explained. In Figure 4, the time-compressed audio PCM signal recorded on the track segment A₁ is obtained from the audio signal during periods up to and including the period (a) and is modulated by PCM and compressed in the audio signal recording processor 21. Similarly, the signal recorded on the track segment A₂ corresponds to the audio signal during the periods (b) - (g), and the signal recorded on the track segment A₃ corresponds to the audio signal during the periods (h) - (m). Figure 7 shows an embodiment of the audio signal recording processor 21 shown in Figure 5. In Figure 7, the numerals 97a and 97b denote analog compressors, the numerals 98a and 98b denote analog-digital converters, and the numeral 99 denotes a digital signal processor which operates to perform time compressing, error compensation and other operations on the received digital signals. The numerals 100, 101 and 102 respectively denote a phase detector, a voltage controlled oscillator and a divider, which elements form a phase locked loop. The numeral 103 denotes a pulse delay circuit using the output pulses from the divider 102 to convert the pulse I or the track indicating pulse Li having the frame frequency into a gate pulse Gi, shown in Figure 6. The gate pulse Gi is used in the recording amplifying circuit 20. The divider 102 shown in Figure 7 generates several trains of pulses having the the frequencies 2Fh, 16 Fh, 184 Fh, and 368 Fh. The A/D converters 98a and 98b shown in Figure 7 receive the pulse having the frequency 16 Fh and convert the analog signals from the analog compressor 97a and 97b to digital signals of 8 bits. As seen in Figure 7A, the digital processor 21 has random access memories (RAMs 1, 2, 3 and 4) 99A - 99D for time-compressing the digital signals at 1/23 compressing rate. That is, during the high level period of the pulse Li shown in Figure 6, the RAMs 1 and 3 write the digital signals by using the clock pulse having the frequency 16 Fh, and the RAMs 2 and 4 read the digital signals by using the clock pulse having the frequency 368 Fh. On the other hand, during the low level period of the pulse Li shown in Figure 6, the RAMs 1 and 3 read the digital signals by using the clock pulse having the frequency 368 Fh, and the RAMs 2 and 4 write the digital signals by using the clock pulse having the frequency 16 Fh. The numerals 99E and 99F designate modulating circuits in which the time compressed digital signals are converted to new digital signals which are easy to record on the magnetic tape, that is, "1" level signals are converted to pulses having the frequency 368 Fh and "0" level signals are converted to pulses having the frequency 184Fh. The numeral 99G denotes a matrix circuit in which two converted digital signals from the modulating circuits 99E and 99F, and an error compensation signal (an error correction signal), generates the output signal Ai/Bi/Ci. The pulse delay circuit 103 shown in Figure 7 is made up of a 1/2 divider 103a and a pulse count type monostable multivibrator 103b, as seen in Figure 7B. The monostable multivibrator 103b produces an output having the delay time 215/Fh to the pulse I or Li and a pulse width 44/Fh. Returning to Figures 5 and 6, the frequency of the timing pulse K is explained hereinafter. In the tape pattern shown in Figure 3, the slant track corresponding to 180° of the wound angle is divided into six track segments B - F and a part of segment G, i.e., involve periods (c) through (h). The 180° of the wound angle correspond to the pulse width of the output pulse I shown in Figure 6. Accordingly, for the timing pulse K, it is necessary to use a pulse which is phase-locked to the output pulse I and has twelve times the frequency thereof. In the 8 mm Video type of NTSC format, the frequency of the cylinder motor 26 is about 30 Hz. So, in the case where the frequency of the crystal oscillator 39 is 3.58 MHz, to obtain a frequency of 30 Hz, N₁ x N₂ xN₃ ≒ 119,448 The output signal M from the delay circuit 35 is synchronized in phase to the output pulse Io. So, by setting the dividing ratio N₃ = 12, the timing pulse K is obtained. The divider 34 divides the timing pulse K to one twelfth, and produces the parallel output pulses L₁ - L₆ having six different phases; that is, 0 degree, 30 degrees, 60 degrees, 90 degrees, 120 degrees, and 150 degress. As described before, the data selector 36 selects one of the parallel output pulses L₁ - L₆ as the track indicating pulse, for example, the pulse L₁ in the case where the signal is recorded on the information track A, and the pulse L₂ in case that the signal is recorded on the information track B. The dividing ratios N₁ and N₂ of the dividers 38 and 40 are explained. As N₃ equals 12, N₁ x N₂ ≒ 9954 By reason of simplifying the servo system of the capstan motor 45, N₄ = N₅ = 1 In this case, if N₂ equals 1, the output frequency of the divider 41 becomes about 360 Hz, and N₁ equals about 9954. Figure 8 shows an embodiment of the recording amplifying circuit 20 shown in Figure 5. In Figure 8 the numeral 149 denotes a mixing circuit for the video signal and the pilot signal and the numeral 150 denotes a mixing circuit for the compressed audio PCM signal and the pilot signal. The numerals 151 and 152 designate switches for switching the signals, and the numerals 153 and 154 denote switches for squelching. When the levels of the control signals applied to the switches 151, 152, 153 and 154 are low, the terminals V and N thereof are selected. On the other hand, when they are high, the terminals A and S thereof are selected. The numerals 155 and 156 denote driving amplifiers and the numeral 157 designates 2-channel rotary-transformers. The numerals 159, 160, 161 and 162 denote AND CIRCUITS. As already indicated, the time for recording the compressed audio PCM signal is determined by the signal Gi from the audio recording processor 21, and the signal Gi along with the pulse I, Li (depending on switch 48) control the gates 159 - 162 to operate the switches 151 - 154 to selectively supply the video and compressed audio signals to the heads 23a and 23b with the proper timing. Next, the recording of the tape pattern shown in Figure 9 is explained. Figure 9 shows a tape pattern wherein another audio signal is recorded on the information track B of the tape after another audio signal has been already recorded on the information track A. This may occur when the tape is run in one direction to record the track A, and then is run in the opposite direction to record the track B, for example. On the other hand, after recording the track A by running the tape in the direction 6, for example, the tape may be rewound and run in the direction 6 again to record the track B, or vice versa. When the signal is recorded on the information track B, the data selector 36 shown in Figure 5 selects the track indicating pulse L₂. Accordingly, the audio signal corresponding to the periods up to and including the period (b) is recorded on the track segment B₁, the audio signal corresponding to the periods (c) - (h) is recorded on the track segment B₂, and the audio signal corresponding to the periods (i) - (n) is recorded on the track segment B₃ and so forth. The pilot signal recorded on the track segment B₁ has the frequency f₁ or f₃, and in Figure 6 it is shown as f₁. So, the pilot signals of the frequency f₃, f₄ f₁, f₂,f₃.,f₄ and f₁ are respectively recorded on the track segments B₁, B₂, B₃, B₄, B₅, B₆ and B₇. Referring to Figure 9, there is the difference of about half pitch between the center of the track segment A, and the center of the track segment B₁. As both of the information tracks A and B are not simultaneously recorded, the relative position of the track segments A₁ and B₁ cannot be controlled exactly. However, as there is little possibility that the signals will be simultaneously reproduced from the information tracks A and B shown in Figure 9, the difference in position between the track segment A₁ and the track segment B₁ will cause no problem in the reproduction of the recorded information. Namely, in the case of reproducing only the information track A, it is necessary to detect the pilot signal when the heads 23a and 23b track the information track A. Accordingly, the pilot signal recorded on the information tracks, except for the information track A, does not disturb the tracking servo system. A magnetic reproducing apparatus of this invention will be explained later in detail by reference to Figures 12 through 22. Figure 10 shows another specific example of the tape pattern shown in Figure 3. In Figure 10, seven time-compressed audio PCM signals T₁ - T₇ are respectively recorded on the information tracks A - G. All segments T₁₁, T₁₂, T₁₃ ... of the time-compressed audio PCM signal T₁ is recorded on the information track A. Seven segments on each slanting track, for example, T₁₁, T₂₁, T₃₁, T₄₁, T₅₁, T₆₁ and T₇₁, are recorded in sequence. Accordingly, the same pilot signal f₂ is recorded on the seven segments T₂₁, T₃₁, T₄₁, T₅₁, T₆₁, T₇₁ and T₁₂. The numeral 117 denotes the tracking pulse recorded on the second option track 9, which tracking pulse is used for the tracking servo similarly to the pilot signal. The reason for this is that one type of reproducing apparatus can only reproduce the tracking pulse for the tracking servo and another type of reproducing apparatus can only reproduce the pilot signal. Figure 11 is a block diagram of an essential part of the apparatus for recording the tape pattern shown in Figure 10. The block diagram corresponds to the audio processor 21 and the recording amplifying circuit 20 shown in Figure 5. The numerals 121a and 121b to 127a and 127b denote the input terminals for seven stereo audio signals. The numerals 131 - 137 designate audio processors producing the time-compressed audio PCM signals. The numeral 144 denotes a switch-group which has a control terminal 143. A control pulse supplied to the control terminal 143 is generated by a flip-flop 142, having an input terminal 141 for receiving a pulse, for example, the gate pulse G₁ shown in Figure 6. The numerals 145, 146 and 147 denote mixers. The control pulse generated from the flip-flop 142 has the same form as the pulse L₁ shown in Figure 6. In addition, the audio processors 131 - 137 are each provided with an information track selecting signal Li which provides for a time separation of the output signals T₁ - T₇, i.e., each of the time-compressed audio PCM signals T₁ - T₇ is produced in a respective one of the tracks A - G. Thus, the signals T₂ - T₆ can be applied through the mixer 145 to the respective mixers 146 and 147 without interference. At the same time, the switch group 144 changes the state X or Y at the rate of 60 Hz. The mixers 146 and 147 mix the time-compressed audio PCM signals T₁ - T₇ and the pilot signal. The output signals of the mixers 146 and 147 are respectively amplified by the recording amplifiers 148 and 138 and are supplied to the heads 23a and 23b. Figure 12 shows a block diagram of an embodiment of a reproducing apparatus of the present invention. In Figure 12 the numeral 49 denotes a reproducing amplifying circuit, the numeral 50 denotes a video signal reproducing processor, the numeral 51 designates an output terminal for the reproduced video signal, and the numeral 52 denotes an audio signal reproducing processor. The audio signal reproducing processor 52 receives a reproduced PCM signal Si and the timing pulses I', Li' and produces 2-channel audio signals to output terminals 53 and 54. The numeral 55 denotes a linear amplifier, the numeral 56 denotes a switch, the numeral 57 denotes a bandpass filter, and the numerals 58 and 59 denote gate circuits. The numeral 60 denotes a converter which produces the product of the output signals of the gate circuits 58 and 59. The numerals 61, 62 and 63 respectively denote a gate circuit, a bandpass filter having a central frequency f h and a high Q-factor, and a bandpass filter having a central frequency 3fh and a high Q-factor. The numerals 64 and 65 denote amplitude detectors, the numeral 66 denotes a differential amplifier, the numeral 67 denotes an inverter and the numeral 68 denotes a switch. The numerals 28, 60, 62, 63, 64, 65, 66, 67 and 68 form a tracking-error detecting circuit for a tracking system having four pilot signals of different frequency. The numeral 69 denotes a sample hold circuit, and the numeral 70 denotes a delay circuit having a delay time longer than the delay circuit 35 shown in Figure 5. The numerals 71, 72 and 73 respectively denote an inverter, a switch and a divider having 1/9954 dividing rate. The numeral 74 designates a divider having one sixth and one twelfth dividing rates, and which produces the track indicating pulses Li' and the gate pulses Gi'. The numerals 75 and 76 respectively denote a data selector and a switch. Referring to the apparatus shown in Figure 12, there are three operating modes as described below: (1) to simultaneously reproduce the video signal recorded on the information tracks B - G and the compressed audio PCM signal recorded on the information track A; (2) to reproduce the compressed audio PCM signal recorded on one of the information tracks B - G; (3) to reproduce the compressed audio PCM signal recorded on the information track A. Figure 17 shows the operating position of the switches 48, 72, 76 and 56 for each of the above-listed operating modes. In the first operating mode, the reproduced signals from the heads 23a and 23b are the signals N₁', O₁' shown in Figure 13. The video signal R₁ and the compressed audio PCM signal S₁ are produced from the reproducing amplifying circuit 49. The pilot signal P' contained in the video signal R₁ is pulled out by the BPF 57 and is supplied to the tracking servo system. In this case, during all periods when the level of the gate pulse Gi' of the data selector 75 is high, the gates 58, 59 and 61, and the sample hold circuit 69 are in the ON-state. It is sufficient that one of the gates 58, 59 and 61, and the sample hold circuit 69 is inserted into the signal path. However, it is desirable that one of the gates 58, 59 and 61 may be used together with the sample hold circuit 69. In Figure 17 the description N/A means that either the terminal N or the terminal A is selected. In the second operating mode, for example, reproducing the compressed audio PCM signal from the information track B, the reproducing signals are the signals N₂,, O₂'. The output signal from the reproducing amplifying circuit 49 is the compressed audio PCM signal S₂. In order to detect a tracking error from the pilot signal, in the compressed audio PCM signal S₂, the gate pulse G₂' is applied to the gates 58, 59 and 61, and the sample hold circuit 69. In the third operating mode, the apparatus reproduces the pilot signals f₂ and f₄ recorded by the head 23a, and the pilot signals f₁ and f₃ recorded by the lead 23b. So the switch 76 selects the terminal A. Figure 14 shows a block diagram of the second embodiment of the reproducing apparatus of the present invention. The main difference from the apparatus shown In Figure 12 is that a switch denoted by the numeral 77 is provided instead of the switch 76. Figure 18 shows the motion of the switches 48, 72, 77 and 56. Figure 15 shows a block diagram of the third embodiment of the reproducing apparatus of the present invention. The main difference from the apparatus shown in Figure 12 is that an inverter denoted by the numeral 79 and a switch denoted by the numeral 78 are provided instead of the switch 72. Figure 19 shows the motion of the switches 48, 78, 77 and 56. Figure 16 shows a block diagram of the fourth embodiment of the reproducing apparatus of the present invention. The main difference from the apparatus shown in Figure 12 is that the inverter 79 and the switch 78 are provided instead of the switch 76. Figure 20 shows the motion of the switches 48, 72, 78 and 56. Figure 21 shows a block diagram of an embodiment of the reproducing amplifying circuit 49 shown in Figure 12. The numerals 81 and 82 denote input terminals, the numeral 83 denotes an output terminal for the compressed audio PCM signal recorded on the information tracks B - G and the video signal, the numeral 84 denotes an output terminal for the compressed audio PCM signal, the numeral 85 denotes an input terminal for the pulses I' and Li', the numerals 86 and 87 denote head amplifiers, the numerals 88 and 89 denote switches, the numeral 90 denotes an inverter, and the numerals 91 and 92 denote buffer amplifiers. In general, the gain of the buffer amplifier 91 is about 10 dB larger than that of the buffer amplifier 92. Any leakage of the compressed audio PCM signal to the video signal becomes a visual interference, but leakage of the video signal to the compressed audio PCM signal produces no problem if the level of the video signal is smaller than a predetermined threshold level. Further, it is desirable to produce as large a chrominance signal or pilot signal as possible. Therefore, the linear amplifier 55, which is provided in the apparatus shown in Figures 12, 14, 15 and 16 to amplify the pilot signal obtained from the signal at the output terminal 34. Figure 22 shows a diagram of an embodiment of the sample and hold circuit 69 used in the apparatus of the present invention. In Figure 22, the numerals 92, 93, 94 and 95 respectively denote an input terminal, a control terminal receiving the gate pulse Gi', an output terminal and a condenser. During the time when the level of the gate pulse Gi' at the control terminal 93 is high, the signal supplied to the input terminal 92 is straight-forwardly transferred to the output terminal 94. On the other hand, when the level thereof is low, the voltage indicative of the tracking error is held at the condenser 95. All the gates 58, 59 and 61 shows In Figures 12, 14, 15 and 16 transfer the input signal, when the gate pulse G1' is high, and block the input signal, when the gate pulse Gi' is low. There are many positions which the gates 58, 59 and 61 are inserted. However, it is desirable to insert the gates into the input sides of the BPFs 62 and 63 in consideration of the DC offset. Figure 23 shows a block diagram of an embodiment of the audio reproducing processor 52 shown in Figure 12. In Figure 23, the numeral 104 denotes a digital signal processor constructed by a time-expand circuit, an error compensating circuit, etc., the numerals 105a and 105b denote a digital-analog converter, and the numerals 106a and 106b denote analog expand circuits which have a reverse characteristic to the analog compressors 97a and 97b. The numerals 107, 108 and 109 respectively denote a phase detector, a voltage control oscillator and a divider. The detail explanation of the analog expanders 106a and 106b and the D/A converters 105a and 105b, is omitted too, since they are well known to persons having ordinary skill in the art. The digital signal processor 104 performs a function which is the inverse of that performed by the digital signal processor 21, described in detail in conjunction with Figure 7A. Next, a new editing system of this invention is explained. Figure 24 shows a schematic diagram for explaining the new editing system. Referring to Figure 24 the numeral 171 denotes a part of the information track A in which a digital signal is recorded. The numeral 173 denotes a part of the information track C in which another digital signal is recorded. The editing system transfers the digital signal recorded on the part 171 to the part 173 via a memory denoted by the numeral 172. In general, a unit of the digital signal is called a word. As each of the words is successively recorded on the tape, a synchronous signal is inserted every plurality of words in order to know the heading of each word. The group of the words with the synchronous signal is called a block. Also, a block code for distinguishing the block and other data are recorded on the part in which the synchronous signal is recorded, and which is called a pre-block. Further, a post-block is provided as well. The editing system using the block codes is explained by using Figures 25A and 25B, which show schematic diagrams of the information track. Now it is assumed that the quantity of the digital signal recorded on the part 171 shown in Figure 25A is larger than the capacity of the memory 173. An initial block code of the part 171 recorded on the information track is BC - IA, and a last block code thereof is BC - EA. A small part denoted by the numeral 171-3 is a data block having the block code BC - EA. Also, the numerals 171-1, 171-2 and 171-4 denote data blocks. In the editing operation, the block codes BC - IA and BC - EA are assigned. Thus, the quantity of data of the part 171 is compared with the capacity of the memory 172. If the former is larger than the latter, the part 171 is divided into the small parts 171-1 and 171-2. The block code BC - MAE is the last block code of the small part 171-1 and the block code BC - MAI is the first block code of the small part 171-2. That is, the part 171 is divided into small parts, each of which is capable of being stored in the memory 173, and transferred to the information track C. In Figures 25A and 25B, P and R respectively denote the reproducing data and the recording data. The data code BC - IC is for the data recorded on the information track C and is indicated in order to record the part 171 on the next part of the information track C. Accordingly, the block code BC - IC, the small part 171-1, the block code BC - MAE and the small part 171-4 are respectively recorded in the positions of the block code BC - IA', the part 171-1', the block code BC - MAE' and the part 171-4' shown in Figure 25B. Similarly, the block code BC - MAIE, the part 171-2, the block BC - EA and the part 171-3 are transferred. In this case, for detecting the necessary block codes, the tape is properly supplied and taken up. This tape carrying operation can be automatically performed by detecting the block codes as well. Further, the block codes are generally a series of the sequential numbers. Therefore, each of the block codes recorded after the block code BC - IC on the information track C can be exchanged for the sequential numbers of the block code BC - IC. Figure 26 shows a flow chart of an embodiment of the editing system of this invention explained by Figures 24, 25A and 25B, and Figure 27 shows a block diagram thereof. Referring to Figure 26, at the starting point (1 ○ ), the name of the information track, the initial block code and the last block code of the reproduced part are input (2 ○ ). Before the data of the reproduced part is stored in a RAM, it is executed to check whether the data overflows the capacity of the RAM (3 ○ ). If the data overflows it, the data is divided into smaller sizes than the capacity (4 ○ ). Dividing points obtained by the upper step are stored until the edigint is over (5 ○ ). Next, the initial block code and the last block code of the first small part of the divided data is read out and temporarily stored (6 ○ ). Then, the recording/reproducing apparatus is set to the reproducing state, and searches the initial block code (7 ○ ). After the initial block code is detected, the data is stored in the RAM until the last block code (8 ○ ). Further, it is necessary to record the data stored in the RAM on the recording information track. So, firstly, the name of the recording information track and the initial block code are input ( ). The initial block code is stored in the add register ( ). Next, by reproducing the recording information track, the initial block code is detected (9 ○ ). If the initial block code is detected, from the next block the apparatus is set to the recording state and the data of the RAM is recorded. By the steps aforementioned, editing the data of the first part of the reproducing information track is over. Next, the initial block code and the last block code of the second part of the reproducing information track is read out (6 ○ ). Further, the number of blocks which have been recorded at the former steps is added to the content of the add register. The resultant of this addition becomes the initial block code of the next part of the recording information track. After tha, the above float is repeated until the remaining part becomes zero. Referring to Figure 27, the numeral 201 denotes the recording/ reproducing apparatus of this invention. The numerals 202 - 206 designate terminals for the state indication. The numeral 207 denote a key board for editing, by which the names of the reproducing information track and the recording information track are input. The names are stored in a register denoted by the numeral 208, and supplied to a sequence logic circuit denoted by the numeral 209. Similarly, the initial block code and the last block code are supplied and stored. Next, in means for deciding the length of the data denoted by the numeral 201, the length of the data is compared with the number of the blocks corresponding to the capacity of the RAM 218, which is stored in the RAM size memory 211. Further, if the length of the data is longer than the capacity of the RAM 218, the means 210 divides the data into a proper length smaller than the capacity of the RAM 218, and generates an intermediate block code corresponding to dividing points, which is stored in a code register denoted by the numeral 212. The initial block code of the recording information track is transferred to an add register denoted by the numeral 213 and supplied to the sequence logic circuit 209. The block codes of the reproducing information track are produced from a terminal denoted by the numeral 214 of the apparatus 201, supplied to a code coincident circuit denoted by the numeral 215, and compared with the output of the code register 212 or the add register 213 for detecting the coincidence, which is supplied to the code coincident circuit 215 via the sequence logic circuit 209. The numerals 216 and 217 respectively denote the output terminal of the reproducing data and the input terminal of the recording data, which are connected to the RAM 218. For the sequence logic circuit 209, a PLA (program logic circuit), a microcomputer, etc., are used. As was mentioned above, the present invention can provide a recording/reproducing apparatus which is able to record/reproduce a large amount of information in/from the tape. Further, this invention has useful functions. For example, it is possible for this invention to record the same information on two information tracks in order to have high reliability. If the error rate of the data by recording the information on one information track is about 10⁻³, the error rate of the data by recording the information on two information tracks becomes about 10⁻⁶. Similarly, it is possible for this invention to have high faithfulness in the reproduction of the information. As the lower eight bits of the audio PCM signal are recorded on one information track, the higher eight bits thereof can be recorded on another information track. It is possible for the apparatus of the present invention to record/ reproduce auto reversely. For example, in Figure 3, after the information track A is recorded, the information track C is recorded under the condition that the direction of tape running is reverse. That is, the information tracks A - G are sequentially recorded without rewinding the tape.

Claims: A method for recording information on a tape (1) by rotating heads (23a,23b) in helical scan type magnetic recording apparatus, comprising the steps of: (a) generating a plurality of N track indicating pulses which are phase-locked to the rotation of the rotating heads, each of which corresponds in time to the tracking time by the rotating heads of a respective one of a plurality of N information tracks (A.....G) disposed in parallel of the direction of the tape running; (b) selecting one of said N track indicating pulses; (c) supplying an information signal to the heads in time with the selected track indicating pulse; and (d) generating a pilot signal (P) which sequentially and repeatedly varies in frequency between a number of predetermined frequencies (f₁....f₄) response to the rotation of the heads, and is mixed with said information signal. A recording method according to claim 1, wherein said information signal is a time-compressed PCM audio signal and the timing of time-compressing the PCM audio signal is determined by said selected track indicating pulse. A recording method according to claim 1, wherein said pilot signal has four predetermined frequencies. A helical scan type magnetic tape recording apparatus including a capstan for moving a tape (1), rotating heads (23a,23b) for recording information on the tape (1), a cylinder (23) for rotating the heads, and a cylinder motor (26) for rotating the cylinder (23), comprising: (a) means (39,40,38,34) for generating a plurality or N track indicating pulses, each of which respectively corresponds in time to the tracking time by said rotating heads of a plurality of N information tracks (A.....G) disposed in parallel to the direction of the tape running; (b) means (29,30) for phase-locking said N track indicating pulses to the rotation of the heads; (c) means (36) for selecting one of said N track indicating pulses; (d) means (99G) coupled to said selecting means (36) for supplying an information signal to the heads in time with the selected track indicating pulse; (e) means (28) for generating a pilot signal (P) which sequentially and repeatedly varies in frequency between a number of predetermined frequencies (f₁....f₄) in response to the rotation of the heads; and (f) means (20) for mixing said pilot signal (P) with said information signal. An apparatus according to claim 4, wherein said pilot signal (P) has four predetermined frequencies. An apparatus according to claim 4, further comprising: (g) means (99A.99D) connected to said selecting means (36) for converting an audio signal into a time-compressed PCM audio signal in response to the timing of said selected track indicating pulse and means (99E,((F) for-applying said time-compressed PCM audio signal to said supplying means (99G) as said information signal. An apparatus according to claim 4, wherein the heads (23a,23b) serve for recording the information signal supplied thereto onto one of said N information tracks corresponding respectively to the selected track indicating pulse. An apparatus according to claim 4, wherein the information signal is a time-compressed PCM audio signal and said N information tracks are provided for storing said time-compressed audio PCM signal, said N information tracks being disposed over at least a central portion of the tape in a direction transverse to the tape running direction. An apparatus according to claim 4, wherein two rotating heads (23a,23b) are provided, said two rotating heads (23a,23b) simultaneously tracing at least one of said N information tracks. An apparatus according to claim 9. wherein said two rotating heads (23a,23b) record said pilot signal (P) having the same frequency during the simultaneous tracking of said at least one of said N information tracks. A method for reproducing an information signal from a tape (1) by means of rotating heads (23a,23b) in helical scan type magnetic reproducing apparatus, comprising the steps of: (a) generating a plurality of N track indicating pulses corresponding respectively in time to the tracking time by said rotating heads of a plurality of N respective information tracks (A.....G) disposed in parallel to the direction of the tape running which pulses are phase-locked to the rotation of the rotating heads; (b) selecting one of said N track indicating pulses corresponding to one of said N information tracks having the information signal recorded thereon; (c) reading out from the tape the information signal at the time indicated by said selected track indicating pulse; (d) selecting a pilot signal (P) which is frequency-multiplexed to said read out information signal; (e) detecting a tracking-error signal in accordance with said pilot signal; and (f) using said tracking-error signal in order to control the tape running. A helical scan magnetic tang reproducing apparatus including a capstan for moving a tape (1), rotating heads for reproducing information from the tape (1), a -cylinder (23)for rotating the heads, and a cylinder motor (26) for rotating the cylinder (23), comprising. (a) means (39,73,74) for generating a plurality of N track indicating pulses, each of which respectively corresponds in time to the tracking time by said rotating heads of a plurality of N information tracks disposed in parallel to the direction of the tape running; (b) means (29,30) for phase-locking said N track indicating pulses to the rotation of the heads; (c) means (36) for selecting one of said N track indicating pulses ; (d) means (49,48,72,76,56) coupled to said selecting means (36) for extracting a corresponding information signal from information signals reproduced by heads in time with said selected track indicating pulse; (e) pilot signal selecting means (57) coupled to said extracting means (49,48,72,76,56) for selecting a pilot signal (P' being frequency-multiplexed to said corresponding information signals; (f) detecting means (28,60,62-68) coupled to said pilot signal selecting means for detecting a track-error signal in accordance with said pilot signal; and (g) feedback means coupled to said detecting means (28,60,62-68) for feeding back said tracking-error signal to the capstan. An apparatus according to claim 12, further comprising: sample-hold means (69) disposed between said detecting means (28,60,62-68) and said feedback means for sampling and holding said tracking-error signal during a period other than a period determined by said selected track indicating pulse. An apparatus according to claim 12, further comprising: transmitting means (58,59,61) disposed between said pilot signal (P') selecting means and said detecting means (28,60,62-68) for transmitting said pilot signal during a period determined by said selected track indicating pulse. A method for magnetically recording/reproducing an information signal with a plurality of rotating heads (23a,23b) for recording/reproducing information on/from an oblique track of a magnetic tape (1) wherein a cylinder (23) carries the plurality of rotating heads and a wrapping angle of the magnetic tape around the cylinder is larger than 180°, comprising the steps of: (a) selecting a first mode for recording/reproducing an information signal in the form of a video signal and an audio signal and a second mode for recording/reproducing only an audio signal; (b) upon selecting the first mode, converting the video signal to a frequency modulated video signal and the audio signal to a time-compressed PCM audio signal; (c) generating a pilot signal (P); (d) mixing the pilot signal with the frequency modulated video signal and the time-compressed audio PCM signal for recording therewith; (e) recording the frequency-modulated video signal on a central part of the oblique track of the magnetic tape and the time-compressed PCM audio signal on one of the ends of the oblique track which ends are proximate to an edge of the tape; and (f) upon selecting the second mode, converting the audio signal to a time-compressed PCM audio signal; (g) generating a pilot signal (P); (h) mixing the pilot signal with the time-compressed PCM audio signal for the recording therewith; and (i) recording the time-compressed PCM audio signal on one of a plurality of information segments of the oblique track disposed at least at a central part of the oblique track. A helical scan type magnetic tape recording/reproducing apparatus including a capstan for moving a tape (1), control means for controlling the capstan, a plurality of heads (23a,23b) for recording/reproducing information on respective slant tracks of the tape (1) scanned by said heads, a cylinder (23) for carrying the heads, means including a cylinder motor (26) for rotating the cylinder (23) to effect rotation of the heads, and pulse generator means (27) for generating a pulse in time with the rotation of the heads, comprising: (a) means (39,73,74) for generating a plurality of N track indicating pulses, each of which respectively corresponds in time to the tracking time by said rotating heads of a plurality of N information tracks disposed in parallel to the direction of the tape running; (b) means (36) for selecting one of said N track indicating pulses; (c) means (22a,22b) for receiving an audio signal; (d) means (21) connected to said audio signal receiving means (22a,22b) for converting said audio signal to a time-compressed PCM audio signal; (e) means (17,18) for receiving a video signal; (f) means (32) connected to said video signal receiving means (17,18) for separating a vertical synchronizing signal from said video signal; (g) first switching means (31) for selecting said vertical synchronizing signal or the selected one of said tracking indicating pulses; (h) means (30) for phase-locking the output of said first switching means (31) to the output pulse of said pulse generator means (27); (i) second switching means (48) for selecting the output pulse of said pulse generator means (27) or said selected track indicating pulse and for supplying the selected pulse to said converting means for controlling the timing of the compressing of said audio signal; (j) recording amplifying means (20) connected to said converting means and said video signal receiving means (17,18) for amplifying the output signals thereof and for supplying said amplified signals to the heads; and (k) means (28) connected to said pulse generator means (27) for generating a pilot signal (P) which sequentially and repeatedly varies its frequencies between a number of predetermined frequencies (f₁....f₄) in response to the output pulse of said pulse generator means (27) and for supplying said pilot signal to said recording amplifying means (20). An apparatus according to claim 16. further comprising: (l) reproducing amplifying means (49) for amplifying a reproduced signal reproduced by the heads; and (m) means (52) connected to said reproducing amplifying means (49) for converting a reproduced time-compressed PCM audio signal, contained in said reproduced signal, into a reproduced audio signal in response to an output pulse of said second switching means (48). An apparatus according to claim 17, further comprising: (n) means (28,60,62-68) connected to said reproducing amplifying means (49) for extracting a reproduced pilot signal (P') contained in said reproduced signal, for generating a tracking error signal in response to said reproduced pilot signal (P') and for supplying said tracking error signal to said control means (44) for controlling the capstan. An apparatus according to claim 18, further comprising: (o) means (39,73,79) for generating N gate pulses which are phaselocked to the rotation of the heads; and (p) means (75) for selecting one of said N gate pulses,which correspond to said selected track indicating pulse and for supplying said selected gate pulse to said extracting means for gating a part of said reproduced pilot signal (P'). An apparatus according to claim 19, further comprising: (q) oscillating means (39) for generating a timing signal, wherein said means (39,73,74) for generating N track indicating pulses and said means (39,73,74) for generating N gate pulses include a divider (73) connected to said oscillating means (39) for dividing the output thereof.

Inventors: OHASHI, SHINICHI, SHIBATA, AKIRA
Applicants: HITACHI VIDEO ENGINEERING, INC., HITACHI, LTD.
Application year: 1983
Main classification: G11B5
IPC codes: H04N5, G11B15, H04N9, G11B27, G11B20, G11B5