JPH0429126B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary head tape recorder suitable for use in a PCM tape recorder.

Usually, a VTR1 with a rotating head is used.
Generally, PCM tape recorders can only record in one direction. That is, as shown in FIG. 1, a recording medium, for example, a magnetic tape T, is made to run in the direction shown by arrow D, and a rotating magnetic head (not shown) is made to run in the direction shown by arrow H. One field of information is recorded on the track _T1 , an audio track _T2 for analog video is recorded on the upper end of the tape T, and a track CTL for control signals is recorded on the lower end.

As described above, the conventional PCM tape recorder can basically only perform one-way recording, so its recording time is limited and it is not suitable for long-term recording.

In view of these points, this invention focuses on the fact that PCM recording is recording of digital signals and can compress the time axis, and it is possible to record and lengthen the recording by switching the signal according to the forward and reverse running of the recording medium. The present invention provides a PCM tape recorder that enables time recording.

Hereinafter, this invention will be explained in detail based on FIGS. 2 to 9.

This invention aims to provide a tape recorder with a tape feeding mechanism capable of moving in forward and reverse directions, thereby making it possible to use a reciprocating track. That is, as shown in FIG. 2, when the tape T moves in the forward direction, for example in the direction of arrow D _F , a rotating magnetic head (not shown) that moves in the direction shown by arrow H _F normally moves one field. One field's worth of information is time-base compressed and recorded on a track T _F , which is approximately half of the track on which information is recorded, and a control signal track _CTLF is recorded at the bottom end of the tape T. On the other hand, when the tape T moves in the opposite direction, for example in the direction of arrow D _R ,
When the head moves in the direction indicated by the arrow H _R , information for one normal field is compressed on the time axis and recorded on the remaining approximately half track _TR , and a control signal track CTL is recorded at the upper end of the tape T. _R
be recorded. In other words, if the tape winding range is approximately 180 degrees as shown in Figure 3, the range recorded in the forward direction is 90-GT/2, and the range recorded in the reverse direction is also 90-GT/2. Become. Here, GT stands for guard track. And a track T _F where information is recorded depending on the direction of tape travel.
The inclination angle and length of and T _R will be different. However, in reality, the tape speed is 2 cm/sec compared to 5 m/sec, so it can be seen that there is almost no difference.

Figure 4 shows the relationship between head travel and tape travel. In the figure, the solid line represents the head travel locus when the tape is stopped;
The broken line represents the trajectory of the head moving in the opposite direction to the tape running direction, that is, the case of the forward direction (D _F ) described above, and the broken line represents the head moving in the same direction as the tape running direction. The traveling trajectory of
In other words, they each represent the case of the above-mentioned reverse direction (D _R ). Although the angle and length of the track will continue to differ depending on the tape running direction, it is clear that there is no problem in practical use.

FIG. 5 shows the configuration of an embodiment of the present invention. In the figure, 1 and 2 are input terminals to which an L channel acoustic signal and an R channel acoustic signal are respectively supplied, and these signals are passed through line amplifiers 3 and 4, respectively, which perform signal level conversion and impedance conversion. and is supplied to one input terminal of adders 5 and 6. The output signal of the dither generation circuit 7 is supplied to the other input terminals of the adders 5 and 6. This dither generating circuit 7 is a circuit that generates noise in order to suppress the occurrence of high-order distortion due to quantization when the signal level is small. The output signals of the adders 5 and 6 are supplied to sample-and-hold circuits 10 and 11 via low-pass filters 8 and 9 for preventing so-called aliasing, which causes a type of distortion in the fundamental wave. These sample and hold circuits 10 and 11 sample and hold the signals, which are passed through the multiplexer 12 to the A/
The signal is supplied to the D converter 13. Here, the sampled analog signals are converted into codes corresponding to the respective sample values, that is, digital signals, and then written into a storage device at the next stage, such as the RAM 14. The signal from the RAM 14 is read out after a predetermined time, and redundant bits for error detection and error correction are added in the next stage correction code addition circuit 15 for error detection and error correction to correct code errors that occur during playback due to dropouts and the like. The output signal from the additional circuit 15 is subjected to FM modulation in an FM modulator 16, and then supplied to a recording-side rotating magnetic head 18 through a recording amplifier 17, where it is recorded as a PCM signal on a recording medium such as a tape (not shown).

This is the configuration of the recording side of a commonly used PCM tape recorder.

On the other hand, the PCM signal reproduced from the tape by the rotary magnetic head 19 on the reproduction side is supplied to the FM demodulator 21 via the reproduction amplifier 20, where it is demodulated, and then sent to the correction circuit 22 to detect code errors caused by dropouts, etc. Corrections will be made. Further, the digital signal, which was compressed in the time axis during recording, is expanded in the storage device such as the RAM 23, and then the digital signal is converted into an analog signal in the D/A converter 24. The output signal of the D/A converter 24 is divided into an L channel signal and an R channel signal in a multiplexer 25, and is passed through a low pass filter 2.
6 and 27 to line amplifiers 28 and 29, and output terminals 30 and 3 on the output side thereof.
1, the reproduced original L channel and R channel audio signals are extracted.

This configuration is a configuration on the playback side of a commonly used PCM tape recorder.

Now, in the present invention, as mentioned above, it is necessary to record the information of one normal field by compressing the time axis to approximately half according to the forward and reverse directions of tape running. The frequency of the reference oscillator 32 is divided to 1/10 by the frequency divider 33 to obtain a clock signal φ ₀ of 50 kHz, and this clock signal φ ₀ is used to convert the signal supplied from the A/D converter 13 to the RAM 14. Write it down. Also, in this case, the A/D converter 13
The same clock signal φ ₀ is supplied to the sample and hold circuits 10 and 11, and a signal of φ ₀ whose frequency is further divided by 1/2 by a frequency divider 34 is supplied as a sampling signal.

On the other hand, the RAM 14 is read using a clock signal φ _H (2.5φ ₀ ) having a frequency obtained by dividing the frequency of the reference oscillator 32 into 1/4 by the frequency divider 35, that is, 125 kHz. Note that the relationship between the signals φ _H and φ ₀ is the third
As you can see from the figure, the length of the guard track is
36°, the frequency of clock signal φ _H is equal to the frequency of clock signal φ ₀ from 180/(90-GT/2) = 2.5.
It is set to be 2.5 times. This φ _H signal is supplied to the read terminal R of the RAM 14 through the AND circuit 36. On the other hand, the AND circuit 36 is selectively supplied with a signal corresponding to the forward or reverse direction of tape running. That is, a forward and reverse direction control circuit 37 is provided, and a forward direction command signal is sent to this control circuit 37 from a terminal 38 and a terminal 39.
When a command signal in the opposite direction is supplied, signals having an opposite phase relationship as shown in FIG. 6C and D are outputted to the output side, respectively. This signal is then supplied to the switch circuit 40 as a switching signal. This switch circuit 40 is connected to a terminal 41 which is connected to a vertical synchronizing signal, which is a reference signal for the drum servo during recording, and whose level is reversed from a high level to a low level approximately in the middle of one field as shown in FIG. 6E. A signal is supplied that will cause the When the tape is traveling in the forward direction, the switch circuit 40 is connected to the contact a side, and the terminal 41 sends a signal as shown in FIG.
2 as a control signal. That is, when the supplied control signal is at a high level, the AND circuit 3
As gate 6 opens, switch 40 closes,
When the control signal is at a low level, the operation is opposite to that described above. Therefore, when reading the RAM 14, the clock signal φ ₀ during writing is 2.5
It will be read out using the twice faster clock signal _φH . As a result, when writing to the RAM 14, an information signal as shown in FIG. 6A is stored, but when reading, a time-base compressed signal as shown in FIG. 6B is retrieved. . Then, this signal is supplied to the head 18 via the correction code addition circuit 15 etc. as described above, and the time-base compressed PCM
recorded on tape as a signal. In other words, the second
In the figure, the signal is compressed on the time axis and recorded on the track T _F of the tape T.

On the other hand, when a switching signal as shown in FIG. 6D is supplied from the control circuit 37 to the switch circuit 40 based on a signal instructing the tape running direction to be reversed, the switch circuit 70 switches to the contact b side, The signal from 41 passes through the contact b side of the switch circuit 40,
The signal is inverted by an inverter 43 and supplied to an AND circuit 36 and also to a switch circuit 42 .
Therefore, in this case as well, the time-base compressed PCM signal is recorded on the tape via the head 18 in the same manner as described above. In other words, in FIG. 2, the signal is compressed in the time axis and recorded on the track _TR of the tape T. 44 is a capstan servo control signal generating circuit which generates a signal for controlling the capstan servo system in forward and reverse directions in response to an output signal from the control circuit 37 corresponding to the tape running direction.

On the other hand, in the case of reproduction, the switch circuit 45 is controlled by the output signal from the control circuit 37. That is, when the tape is running in the forward direction, the switch circuit 45 is connected to the contact a side, and when the tape is running in the reverse direction, it is connected to the contact b side. Also terminal 4
6 supplies a control signal similar to the signal shown in FIG. 6E to the common terminal of the switch circuit 45. Therefore, when the switch circuit 45 is connected to the contact a side, that is, when the tape is running in the forward direction, the high level of the control signal from the terminal 46 opens the gate of the AND circuit 48 and closes the switch circuit 47. When the control signal is at a low level, the operation is opposite to that described above. The other input terminal of the AND circuit 48 is connected to the clock signal φ _H obtained as described above.
That is, a clock signal 2.5 times faster than the clock signal φ ₀ is now supplied as a write signal.
Therefore, the signal reproduced from the head 19 is
The data is written to the RAM 23 at the same speed as when it is read during recording.

The information written in the RAM 23 in this way is read out by the clock signal φ ₀ from the frequency divider 33, that is, the recorded information is extracted with time axis expansion and converted into an analog signal by the D/A converter 24. After that, the signals are outputted as L channel and R channel acoustic signals to the output terminals 30 and 31 via the multiplexer 25 and the like as described above.

On the other hand, when the tape is running in the opposite direction, the output signal from the control circuit 37 causes the switch circuit 45 to switch to the contact b side, and the control signal from the terminal 46 is inverted by the inverter 49 and then supplied to the AND circuit 48. The signal is supplied to the switch circuit 47. Therefore, in this case as well, the signal reproduced by the head 19 is written to the RAM 23 at the same speed as the reading speed during recording, and is read out at the same speed as the writing speed during recording. In other words, information recorded with time axis compression is time axis expanded and reproduced as the original signal. The signals from the RAM 23 are outputted as L channel and R channel audio signals to the output terminals 30 and 31 via the D/A converter 24, multiplexer 25, etc. as described above.

7 to 9 show other embodiments of the present invention, and in each figure, each reference numeral used in FIG. 2 has the same meaning.

First, in the embodiment shown in FIG. 7, the control track recorded in advance in the forward direction is used in the reverse direction.
Take the timing while reading the control signal from CTL _F. In this case, it is necessary to record the forward direction first. If you stop the tape recorder midway in the forward direction and want to start recording again, there is an inconvenience that the control signal of the control track CTL _F will not be connected to the track in the reverse direction. In such cases, there is no problem.

In addition, in the embodiment shown in FIG. 8, a PCM signal of, for example, 2 megabits/second is divided into four tracks and recorded, considering that a transmission rate of about 8 megabits/second is currently possible. That is, in the figure, when the tape T is running in the forward direction (D _F ), the first PCM signal is recorded on the track T _F1 and the second PCM signal is recorded on the track T _F2 . Further, control signals are recorded on control tracks CTL _F1 and CTL _F2 on the lower side of the tape T in accordance with the first and second PCM signals, respectively.

On the other hand, when the tape is running in the reverse direction (D _R ), the first PCM signal and the second PCM signal are recorded on tracks T _R1 and T _R2 , respectively. Along with this, control signals are recorded on the control tracks CTL _R1 and CTL _R2 on the upper side of the tape T, respectively.

Further, in the embodiment shown in FIG. 9, normally the L channel signal and the R channel signal are recorded alternately and continuously within one field, but here, the L channel signal and the R channel signal are recorded alternately and continuously within one field. The signal is divided and recorded. That is, in the figure, when the tape T is running in the forward direction (D _F ), the L channel signal is recorded on the track T _FL and the R channel signal is recorded on the track T _FR , while the tape is running in the reverse direction (D F ). _DR ), the L channel signal is recorded on the track _TRL , and the R channel signal is recorded on the track _TR . Further, the control signal is recorded on the control track CTL _F at the bottom end of the tape T in the case of the forward direction, and is recorded on the control track CTL _R at the top end of the tape T in the case of the reverse direction.

As described above, according to the present invention, in a PCM tape recorder that currently can only record in one direction,
The recording medium is of a reverse type that runs in both forward and reverse directions, and the signal supplied to the rotating magnetic head is switched depending on the direction of travel of the recording medium, so that the time axis of the signal is compressed and recorded on the recording medium. This makes it possible to perform round-trip recording, and by increasing the bit rate, it becomes possible to perform multi-track recording, thereby making it possible to record for a long time.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the tape running direction and the head running direction in a conventional PCM tape recorder, FIGS. 2 to 4 are diagrams for explaining the present invention, and FIG. FIG. 6 is a diagram for explaining the operation of FIG. 5, and FIGS. 7 to 9 are diagrams showing other embodiments of the present invention. 10 and 11 are sample and hold circuits, 13 is an A/D converter, 14 and 23 are RAM, and 16 is
FM modulator, 18, 19 rotating magnetic head, 21
is an FM demodulator, 24 is a D/A converter, 32 is a reference generator, 33, 34, 35 are frequency dividers, 36,
48 is an AND circuit, 37 is a forward and reverse control circuit, and 40, 42, 45, and 47 are switch circuits.

Claims (1)

[Scope of Claims] 1. Means for time-base compressing an input signal to generate a recording signal; Means for running the tape in both forward and reverse directions; and a means for running the tape while the rotating head is scanning the tape. means for selectively supplying the recording signal to the rotary head for a predetermined period depending on whether the tape is forward or reverse, the recording signal being recorded in a predetermined area of the tape. head tape recorder. 2. Means for running the tape in both forward and reverse directions, and means for selectively supplying reproduction signals from the rotary head for a predetermined period of time depending on whether the tape is running in the forward or reverse direction while the rotary head is scanning the tape. A rotary head tape recorder characterized in that the rotary head tape recorder is characterized in that the rotary head tape recorder is provided with means for time-axis expanding the supplied reproduction signal and generating an output signal, and for reproducing the signal recorded in a predetermined area of the tape. .