JPH0437482B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to recording and reproducing information signals in a rotating head type magnetic recording and reproducing device.

[Background of the invention]

Conventionally, various attempts have been made to record PCM audio signals using rotating head type magnetic recording and reproducing devices. However, with these conventional devices, there are drawbacks such as it is difficult or impossible to record and play back audio signals due to reverse running, it is impossible to record and play back long programs, and it is not possible to quickly access the program you want to listen to. Ta.

[Purpose of the invention]

The object of the present invention is to compensate for the drawbacks of the prior art described above, and to provide a recording/reproducing machine for recording and reproducing audio signals during reverse running, multi-channel recording, or a high-quality audio signal recording/reproducing machine.
An object of the present invention is to provide a rotating head type magnetic recording/reproducing device that can be used also as a VTR.

[Summary of the invention]

A feature of the present invention is that in a rotating head type magnetic recording/reproducing device, the winding angle of the tape around the rotating magnetic head device (cylinder) is made small, and the level difference in the tape running system is made small, thereby stabilizing the reciprocating movement of the tape. The object of the present invention is to realize an audio signal recording device capable of reciprocating movement by increasing the number of rotating heads and simply switching the heads. Furthermore, by utilizing these rotating heads, it is possible to perform multi-channel recording or recording/playback of TV signals. Furthermore, since the tape running system is simplified, tape loading becomes easier, and the apparatus can be made smaller and lighter.

[Embodiments of the invention]

An embodiment of the present invention will be explained based on FIGS. 1 to 3. FIG. 1 shows the tape running system, FIG. 2 shows the head arrangement in the cylinder section, and FIG. 3 shows the tape pattern recorded on the magnetic tape.

In FIG. 1, 1 is a cassette in which a supply reel 2 and a take-up reel 3 are arranged.
The magnetic tape 4 (hereinafter simply referred to as tape) is placed in the guide 2 in the cassette before being loaded onto the cylinder 9.
0, 21 and is at position 4' in the figure.
Also, at this time, the entrance side pinch roller 14, the entrance side pinch roller guide 16, the entrance side width regulation guide 5, and the entrance side inclined guide 6 are respectively 14', 16', 5',
6', and the outlet pinch roller 15, outlet pinch roller guide 17, outlet width regulation guide 8, and outlet inclined guide 7 are located at 15', 17', 8', respectively.
It is located at the 7' position. By loading the tape into the cylinder 9, these tape guides move as shown by the arrows in the figure, forming a tape running path as shown in the figure. As shown in the figure, the tape 4 is spirally wound around the cylinder at a winding angle of just over 90°. In addition, 10 and 11 are an entry side fixed width regulation guide and an exit side fixed width regulation guide, 12 is an entry side capstan, 13 is an exit side capstan, 1
8 is the input side control erase head, 19
is the output side control erase head.
The input side pinch roller 14 and the output side pinch roller 15 are pressed onto the input side capstan 12 and the output side capstan 13, respectively, with appropriate pressing force, and these capstans are rotationally driven by a drive system (not shown). There is. The positions of the entrance-side inclined guide 6 and the exit-side inclined guide 7 are regulated by a position regulating member (not shown) to correct twisting of the tape caused by spirally wrapping the tape around the cylinder. The tape running system shown in the figure is of a double capstan drive type with the cylinder 9 at its center, and can run the tape at a constant speed with an appropriate tape tension using a well-known technique. Further, the difference in height between the tape on the entrance and exit sides of the cylinder due to the tape being wound spirally around the cylinder is corrected by tilting the cylinder, so that the tape enters and exits the cassette at the same height. Furthermore, as is clear from Figure 1, this tape running system has a nearly symmetrical shape with the cylinder at the center, and can run the tape at a constant speed in both forward and reverse directions with the same stability. can do. The cylinder 9 has four rotating heads 24 to 27.
is located. FIG. 2 shows the head arrangement of the cylinder section. Cylinder 9 is a fixed lower cylinder 22
and a rotating upper cylinder 23. The rotation mechanism, driving method, etc. of the upper cylinder are well known, and their explanation will be omitted here. The lower cylinder 22 is provided with a spiral tape guide portion 35, which guides the tape 4 at a wrapping angle of just over 90°, as described above. The rotating heads 24, 25, 26, 27 are
The rotating heads (hereinafter simply referred to as heads) 24 and 26 are arranged at 90° intervals, and as shown in the figure, are arranged with a certain step difference in the direction of the rotation axis. head 2
4 and 25 are at the same height in the direction of the rotation axis, heads 26 and 2
7 are also arranged at the same height in the direction of the rotation axis. Also, heads 24 and 26 have the same azimuth angle, and heads 25 and 26 have the same azimuth angle.
7 has the same azimuth angle with different angles than 24 and 26.

The third diagram shows the pattern of traces recorded on the tape. That is, the heads 24 and 25 cover the upper half of the tape,
Heads 26 and 27 scan the lower half of the tape.
Therefore, in FIG. 3, when the tape runs in the direction of arrow 36 (assumed to be the positive direction), if the signals are recorded in the heads 24 and 25, then 1/4 of the upper cylinder 23
The head 24 scans the tape for a period slightly longer than the rotation period, and a record 28 is formed. During the subsequent period slightly longer than the 1/4 rotation period, signals are recorded in the head 25 and a record trace 29 is formed. The head track widths of heads 24 and 25 are recorded as 28 and 2.
The width is slightly larger than the width P of 9, and so-called azimuth overwriting recording is performed. At this time, a control signal is recorded on the control track 32 by the control erase head 19 for tracking the recorded trace. Similarly, when the tape 4 runs in the direction of the arrow 37 (in the opposite direction), the head 26 forms a recording trace 30 and the head 27 forms a recording trace 31, and the control signal is recorded on the control track 33 by the control erase head 18. Ru. A time code signal is recorded on the center track 34 and is used for searching for recorded programs. As mentioned above, the signal recording and playback period is only 1/2 rotation period per rotation, but when recording audio signals in PCM, time axis compression and time axis expansion during playback are well-known techniques. This is possible and does not pose a problem. In Figure 3, dimension A is the tape width, C ₁ , C ₂ are the control track widths, B ₁ ,
B ₂ are longitudinal signal recording and reproducing tracks 2 respectively.
The track width is 00,300, T is the time code track width, and _G1 to _G4 are the guard band widths between each track.

In this embodiment, the audio signal may be compressed for 1/2 time and recorded. A design example of this embodiment will be described below. Now the cylinder diameter is 40mm and the rotation speed is
Assuming 1800 rpm, the head tape relative speed is
It becomes 3.75m/s. When the stereo audio signal
Assuming a 44KHz, 16-bit sampling PCM signal, the bit rate will be approximately 1.4Mbit/sec. If this is compressed by 1/2 hour, the bit rate is 2.8Mbit/
s, and the recording wavelength per bit is 1.3μ.
This is possible with current magnetic recording and reproducing technology,
This is a value that can be recorded and played back. Now A=8mmC ₁ =C ₂ =
0.6mm, G ₁ = G ₂ = G ₃ = G ₄ = 0.1 mm, T = 0.3 mm, B ₁
= B ₂ = 3.05 mm, P = 10 μ, and the length of the tape wound around cassette 1 is 100 m, each round trip takes 4 hours,
A total of 8 hours of audio signal recording and playback is possible. Furthermore, since the tape wrapping angle around the cylinder is small, fast forwarding and fast reversing are possible while the tape is wound around the cylinder. At this time, the recorded program can be searched using the time code signal recorded on the time code track. Since the recorded program is erased using the overwriting method, it is also possible to use overwriting, and there is no need to provide an erasing head, but if complete erasing is particularly required, the control erase heads 18 and 19 are used. A front view of the heads 18 and 19 is shown in FIG. Part 38 of the control erase head 18 is a control track erasing gap part, 39 is a signal erasing gap part, 40 is a time code signal recording/reproducing gap part, and 41 is a part of the head 18.
42 is a signal erasing gap portion when used as a full-width erasing head, and 42 is a control signal recording/reproducing gap portion. A portion 43 of the head 19 is a control signal recording/reproducing gap portion, 44 is a signal erasing gap portion, and 45 is a control signal erasing gap portion.

FIG. 5a shows a block diagram of the signal recording circuit, and FIG. 5b shows a block diagram of the signal reproducing circuit. In the figure, an input audio signal input to terminal a is converted into a PCM signal by an A/D converter 50, and then time-compressed by a 1/2 time compression circuit 51. This time compression is performed as shown in FIG. 6 based on a signal indicating the cylinder rotation phase from the cylinder tack generator 52. In other words, 1/2 of one cylinder rotation period
The signal portions 68 and 69 corresponding to are compressed by 1/2 time to become portions 70 and 71 of the 1/2 compressed signal,
The timing is determined so that this 1/4 period corresponds to the tape scanning period of the head 24. The next parts 72 and 73 of the PCM audio signal are also converted into parts 74 and 75 of the 1/2 compressed signal,
It is recorded on head 25. This is repeated below. The same applies to the heads 26 and 27. The 1/2 time compressed signal is modulated by a modulator 53 to be suitable for magnetic recording, and then input to a recording amplifier 54. The output of recording amplifier 54 is guided to heads 24-27 via switch circuits 55-58. Switch circuits 55 to 58 are the outputs of a cylinder tack generator 52 and a switch pulse generator 59 for selecting the recording head in response to a running mode signal (forward or reverse running).
It is turned ON and OFF to select the recording head.

During reproduction, the head currently performing reproduction is similarly selected from the output of switch pulse generator 59, selected by switch circuits 60 to 63, and input to preamplifier 64. Preamplifier 6
The output of 4 is demodulated into a 1/2 time compressed PCM signal by a demodulator 65, and then expanded in time by a double time expander 66 to become a reproduced audio PCM signal.
The converter 67 outputs a reproduced audio signal to terminal b. Although not shown in the figure, error correction bits are added to the recorded signal, and errors are corrected based on this during reproduction.

Next, we will discuss an example in which the device of this embodiment can be used as both an audio tape recorder and a video tape recorder.As mentioned above, since the audio signal is compressed by 1/2 time, the video signal If you compress it by 1/2 time, the audio signal will be in the upper half of the tape.
If a video signal is recorded in the lower half, it can be used as a video tape recorder. In this case, round-trip recording and playback is not possible. However, since the video signal has a wide band, the above-mentioned design example lacks the bandwidth of the reproduced signal. for that purpose,
Either increase the cylinder diameter or increase the cylinder rotation speed. For example, if the cylinder rotation speed is set to 3600 rpm, the bandwidth can be more than doubled. In such an embodiment, the video signal may be of the so-called segment recording method, and there is a head switching point in the center of the screen, and the tolerance for skew distortion is strict. However, in the present invention, since the tape winding angle at the cylinder portion is small, the increase in tape tension is small, and therefore the amount of skew is also small. Therefore, this can be corrected by a simple skew correction circuit. When time compression of the video signal is not performed, the video signal is recorded sequentially on the four heads 24, 26, 25, and 27, and the accompanying audio signal is sent to one of the control tracks or the time code track. Just record it. In this case, the reproduction sound quality of the audio signal accompanying the video cannot be expected to be very high, but there are few cases where high quality is required for both at the same time, and there is no problem in practical use. In this case, the basic function of the playback device is a PCM audio or television signal recording/playback device, and as an option,
A format that adds a television signal or PCM audio signal recording/playback adapter is practical. In the case of recording television signals using this method, recording and reproduction can be performed not only in the forward direction but also in the reverse direction due to the symmetry of the running system shown in FIG.

In any case, according to the present invention, there is a degree of freedom in which the number of heads to be used can be selected from two to four depending on the band of the signal to be recorded.

Next, another embodiment of the present invention will be described based on FIG. FIG. 7 shows the recording pattern on the tape of this embodiment. In this example, the audio signal is
After being converted to PCM, the time is compressed to 1/4 and recorded, and recording tracks are distinguished by whether the recording timing is in the first half or the second half of the tape scanning period of the head. A guard part is provided in the middle. This section may also be a separate longitudinal track. That is, recording and playback can be performed on two longitudinal tracks (tracks 76 and 77) when traveling in the forward direction, and on two longitudinal tracks (tracks 78 and 79) when traveling in the reverse direction. Of course, as the time compression ratio increases, the recording signal band also increases, so it is necessary to increase the relative speed of the head tape. The erase head is
Head 1 erase gap corresponding to each track.
This is possible by providing at 8 and 19. For example, the gap portion shown at 39 and 44 in FIG. 4 may be divided into two parts of equal size.

An example of compression of a PCM audio signal in this embodiment is shown in the eighth example.
As shown in the figure. In other words, the time of the PCM audio signal is compressed to 1/4, and when recording on track 76, the time is compressed to 80',
8 for track 77 at time position 81'.
It is recorded by the head 24 as a signal at time positions 0'' and 81''. The same applies to other heads.

In this embodiment, the record trace 28 shown in FIG.
29, 30, and 31 were each divided into two parts,
This is not limited to two, but any number is fine. The compression ratio of the audio signal may be changed accordingly.

Next, an example in which the present invention is used as a television signal recorder/player will be described. In this embodiment, the audio signal accompanying the television signal is recorded in so-called overlap PCM. That is, the overlap of winding around the cylinder of just over 90 degrees shown in FIG. 1 is slightly increased, and a time-compressed PCM audio signal is recorded in this portion.
The recording tape pattern in this case is shown in FIG.

Head 24 first scans the tape and a video signal record 82 is formed. Immediately before this ends, the head 26 begins scanning the tape and the video signal record 8
4 is formed. The head 24 records the time-compressed PCM audio in the overlap area through the guard part 82' of the head and grip, and the recording trace 82'' is 82,8
It is formed on the extension of 2'. Immediately before the head 26 finishes recording the video signal, the head 25 scans the tape and a recording trace 83 is formed. Thereafter, the same process is repeated to form a tape pattern as shown in FIG. 86 is a control track, 87 is a time code track, and 88 is an auxiliary track, which is used for recording auxiliary audio signals and the like. In this embodiment, a design example for recording a digital video signal and a PCM audio signal will be described. Video signals are now processed using 7MHz, 8-bit sampling.
Assuming a PCM video signal, the bit rate is
It becomes 56Mbit/s. In addition, error correction bits are required, so even if various band compression techniques are used, a minimum speed of 50 Mbit/s is required. This is the bit rate of the PCM audio signal mentioned above, which is approximately
This is 17 times faster than 3Mbit/s. There is a considerable difference even when considering the required error correction ability, etc.

In this embodiment, even if the overlap is assumed to be 1/10 of the video image, there is no problem with this because of the above-mentioned relationship. In other words, an overlap of approximately 9° is sufficient, and the increase in tape winding is negligible. In this case, the time compression of the audio signal is 1/10. If a cylinder with a diameter of 40 mm as described in the first embodiment of the present invention is used and the cylinder rotation speed is 7200 rpm,
At 50 Mbit/s, each bit corresponds to a recording wavelength of 0.3 microns, and recording and playback is possible if the characteristics of the head, tape, etc. are improved. In this case, if the above-mentioned cassette is used and the track pitch P is also set to 10μ, approximately one hour of television signal recording and playback will be possible. Of course, the larger the cylinder diameter, the lower the rotation speed. If you want to convert the video signal to a digital signal and record it,
The aforementioned skew at the time of head switching is not a problem. Further, when this device is used as a dedicated audio signal recording/reproducing device, the video signal recording traces 82, 83, 84, 85
All you have to do is divide it into several tracks. In this embodiment, in principle, it is possible to divide the track into 10 tracks, each with 5 tracks on the top and 5 on the bottom. That is, forward running 5
track, 5 tracks in the opposite direction, 1 hour each, total
Can be a 10-hour PCM audio recording and playback device.
Also, as is clear from the above explanation, 5 channels or
Simultaneous recording and playback of 10 channels is possible. In this case, the signal erase gap of the control erase head is set to one track width.
The erase head structure can be simplified by moving the control/erase head in accordance with the track position to be erased. In this case, the recording timing of the time-compressed PCM signal may be changed from that in the case of television signal recording. Figure 10 a, b
In this example, the video signal is recorded as a PCM signal,
A block diagram of a recording/reproducing circuit during reproduction is shown. The input video signal input to terminal V is A/
The D converter 86 converts it into a PCM signal. If necessary, the video signal is divided into a luminance signal and a color difference signal, A/D converted, and time-axis multiplexed.
Next, an error check bit adding circuit 87 adds an error check bit, and a modulating circuit 88 modulates the signal into a signal format suitable for magnetic recording. Modulation circuit 8
The output of 8 is input to the switch circuit 89, and the output of the tack pulse generator 90 is used to control the heads 24, 2.
Only the signals for the recording period of 5 are output. The input audio signal input to the output terminal a is converted into a PCM signal by the A/D converter 96, and then time-base compressed by the time compression circuit 97. The time base compression is performed by using the output of the tack pulse generator 90 so that the time base compression signal exists only for a period corresponding to the overlap period. After an error check bit is added to the time axis compressed PCM audio signal in an error check bit adding circuit 118, it is modulated in a modulation circuit 98 suitable for magnetic recording, and then a switch circuit 99 determines the recording period of the heads 24 and 25. signal is output. The outputs of the switches 89 and 99 are added together in an adder circuit 91 and then supplied to the heads 24 and 25 via a recording amplifier 92. The heads 26 and 27 are also similar to the heads 24 and 25. During reproduction, the reproduction heads 24 and 25 are activated by the switch 10 by the output of the tack pulse generator 90.
At step 1, the head currently scanning the tape and reproducing the signal is selected, and the reproduced signal is amplified by the preamplifier 102, and then received by gates 103 and 104 to receive the output of the tack pulse generator 90, and is converted into a video signal and an audio signal. Separated. For the video signal, the signals from the heads 26 and 27 are added by an adder circuit 109, the original PCM signal is demodulated by a demodulator circuit 110, the error is corrected by an error correction circuit 111, and then the signal is sent by a D/A converter 112. converted into a playback video signal. The reproduced audio signal is similarly added with the signals from heads 26 and 27 by an adder circuit 113, demodulated by a demodulator circuit 114, error corrected by an error correction circuit 115, and then restored to its original time by a time expansion circuit 116. The D/A converter 117 converts the signal into a reproduced audio signal. The same applies to heads 26 and 27 as well as heads 24 and 25.
The reproduced audio signal has a considerable delay compared to the reproduced video signal, but this is about 1/4 of the period of one rotation of the cylinder, and this is a serious problem, especially in a high-speed rotating cylinder like the one in this embodiment. do not become. When using this embodiment as a PCM audio signal recorder, the signal from the tack pulse generator 90 should be output in accordance with the audio signal recording track position, and the output timing of the time compressed audio signal from the time compression circuit 97 should be changed. For example, an audio signal can be recorded at a desired track position. In the case of reproduction, the signal from the desired audio track can be reproduced by changing the time position of the output pulse from the tack pulse generator 90.

Next, another embodiment of the present invention will be described based on FIG. 11. This embodiment is a suitable example in which the present invention is applied to an apparatus that serves both as an audio tape recorder and a video tape recorder. The recording pattern on the tape of this example is shown in FIG. The difference in head arrangement between this embodiment and the previous embodiment is that head 2
The difference in level between 4, 25 and 26, 27 is even larger than that in Fig. 2, and the head 24, 25 has a rotation rate of 1/2 per rotation.
The tape should be scanned in less than four revolutions. For example, if this period is approximately 1/8 revolution, the audio signal will be compressed by 1/4 time and
4 and 25 are recorded as recording traces 119 and 120 on the tape in the longitudinal direction track 123. The video signal is compressed for 1/2 time and recorded as in the previous embodiment, and is recorded as recording traces 121 and 122 on the tape in the longitudinal track 124 portion. Since the video signal band is usually wider than the audio signal band, it is reasonable to use this embodiment in which the video signal recording portion is wider than the audio signal recording portion when overlapping recording of audio signals is not performed. When this embodiment is used as a PCM recording-only device, the recording traces 121 and 122 may be divided into two to create two audio signal recording tracks, as described in the previous embodiments. In this example, the ratio of the upper and lower tracks 123 and 124 is 1:2.
However, by changing the head height difference, this ratio can be changed arbitrarily depending on the required bands for both audio and video signals. In this case, the time compression ratio of the audio signal may be changed depending on the ratio. In the embodiments described so far, a control signal was used to control the tape running, but of course, as a substitute for the control signal, it is also possible to use a tracking pilot signal by frequency multiplexing each recording trace. More self-explanatory. In this case, as described above, since the audio signal can be erased by overwriting, the control and erase heads 18 and 19 can be eliminated, and the tape running system can be extremely simplified. Further, in the embodiments described above, the tape running system was driven by a double capstan, but since the tape running system has good symmetry, sufficiently stable running is possible with a conventional single capstan drive. In addition, in Figure 2, the number of heads at the same height position is set to 2 at 180° intervals, but for example, this could be set to 3 heads at 120° intervals and with different azimuth angles, for a total of 6 heads. The angle at which the tape is wrapped around the cylinder may be a little more than 60°. It is also possible to arrange four heads at 90° intervals, for a total of eight heads, and make the tape wrapping angle around the cylinder 45°. It is generally possible to arrange a plurality of heads in the same manner. Also, in Figure 3, the tape is
Although the upper and lower two longitudinal signal recording/reproducing tracks are divided into two, it is also possible to divide this into three longitudinal signal recording/reproducing tracks: upper, middle, and lower. In this case, they are at the same height and 180 degrees apart. The heads of three pairs of heads with different azimuths arranged at intervals can be placed at different heights, and the tape can be wound around the cylinder at an angle of more than 60 degrees.

From the description of the embodiments described above, it is easy and obvious to extend them to systems having more heads or tracks.

Furthermore, in the description of the embodiments so far, the recording signal has been limited to an audio signal or a television signal, but it may also be used to record any other information signal, such as a digital data signal used in a computer. , it is self-evident.

〔Effect of the invention〕

According to the present invention, a high-density magnetic recording and reproducing device can be realized with an extremely simple tape running system and cylinder structure, and the device can be made smaller and lighter.
This makes it possible to lower prices. In addition, constant-speed tape running in both forward and reverse directions can be achieved with the same running stability, and signals can be easily divided and recorded, so the functions of the device can be expanded, such as recording and reproducing television signals and recording and reproducing by reciprocating. Multi-track capable of
The present invention makes it possible to realize a device that has the functions of recording and reproducing PCM audio signals.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a tape running system according to an embodiment of the present invention, FIG. 2 is a diagram showing the head arrangement in the cylinder part, FIG. 2 a is a plan view, and FIG. 2 b
is a front view, FIG. 3 is a diagram showing the recording pattern on the tape, FIG. 4 is a front view of the control/erase head, FIGS. 5 a and b are block diagrams of the recording/reproducing circuit, and FIG. 6 is the signal FIG. 7 is a diagram showing the recording pattern on the tape according to another embodiment of the present invention. FIG. 8 is a diagram showing the time axis compression of the signal. FIG. 9 is a diagram showing the time axis compression of the signal. FIGS. 10a and 10b are block diagrams of the recording/reproducing circuit, and FIG. 11 shows a recording pattern on the tape according to still another embodiment of the present invention. FIG. 1... Tape cassette, 4... Magnetic tape, 9
... Cylinder, 12 ... Entry side capstan, 13
...Output side capstan, 18...Input side control erase/combined head, 19...Outside control erase/control head, 24, 25, 26, 27
... Rotating magnetic head, 32, 33 ... Control track, 51 ... 1/2 time compression circuit, 200,
300...Signal recording track.

Claims (1)

[Scope of Claims] 1. In a helical scan type magnetic recording and reproducing device that can run a magnetic tape in two directions, forward and reverse, 2n (where n is an integer of 2 or more) rotating magnetic heads are arranged at equal intervals. Approximately 360°/
The magnetic tape runs in contact over 2n, and the 2n rotating magnetic heads sequentially scan the magnetic tape, and divide the magnetic tape into first and second regions in the width direction. and set the first area to 2n
When every other rotating magnetic head of the plurality of rotating magnetic heads scans the second area, every other rotating magnetic head scans the second area, and a narrowband signal is recorded. In the case of recording a broadband signal by compressing the time axis and recording only in the corresponding one of the first and second areas according to the forward and reverse rotation of the magnetic tape, A magnetic recording/reproducing apparatus characterized in that recording is performed in both the first and second areas by running the magnetic tape in one direction.