JPS58155510A - Pcm tape recorder - Google Patents

Abstract

PURPOSE:To attain the reciprocating recording of a medium for multitrack and to obtain a long time recording, by switching signals in respone to both forward and reverse directions of the recording medium and recording the signals after time axis compression. CONSTITUTION:L and R channel signals at terminals 1 and 2 are sample-held 10, 11 with a clock phi0, A/D-converted 13 with a clock phi0 and written in an RAM 14 with the clock phi0. The content of the RAM 14 is read out with a 2.5phi0, given to an FM MOD 16 and a head 18 as a time-axis -compressed signal and recorded on a tape as a PCM signal. An output signal of a switch circuit 40 is given to an AND circuit 36 via an inverter 43 and the readout clock of 2.5phi0 is given to the RAM14 with a command signal from a control circuit 37 of the tape running direction.

Description

[Detailed description of the invention] This invention is a PCM tape recorder.

Usually, PCM f-! using a videotape recorder.
Generally, recorders can only record in one direction. That is, as shown in FIG. 1, a recording medium, for example, a magnetic head fT, is made to run in the direction shown by the arrow, and a rotating magnetic head (not shown) is made to run in the direction shown by the arrow H. Record the situation of one field on track T1, and record audio track D1 for analog video on the upper end of tape T.
.

A track CTL for control signals is recorded at the lower end thereof.

In this way, in the case of a conventional PCM tape recorder, c.

In principle, only one-way recording is possible, so there is a limit to the recording time, and it is not suitable for long-term recording.In view of this, the present invention is based on the fact that PCM recording is capable of recording digital signals. The present invention focuses on the fact that time axis compression is possible, and provides a PCM tape recorder that enables long-time recording by switching signals depending on whether the recording medium runs in both forward and reverse directions.

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

In this invention, the QFO feeding mechanism of a tape recorder is designed to be capable of forward and reverse directions, so that reciprocating tracks can be used. That is, as shown in Figure 2, Chi! T is forward direction e.g. arrow,
When moving in the direction indicated by the arrow HF, one field's worth of information is recorded on track Tr, which is approximately half of the track 0, on which information for one field is normally recorded by a rotating magnetic head (not shown) that moves in the direction indicated by the arrow HF. If you compress the time axis and record it,
, a control signal track CTL is placed at the bottom end of the tape T.
, to be recorded. On the other hand, when the tape T moves in the opposite direction, for example in the direction of the arrow DI, when the head moves in the direction shown by the arrow H1, the information for one normal field is stored in approximately half of the remaining track T. In addition to compressing the time axis and recording, a control signal track CTLI is recorded at the top end of the tape. As shown in FIG. 3, if the tape winding range is approximately 1800 degrees, this indicates that recording is performed in the forward direction. The inclination angle and length of the tracks TF and TI on which information is recorded differ depending on the running direction of the tape. However, in reality it is 5%/I@
Since the tape speed is 2 ca/#@6 compared to e, it can be seen that there is almost no difference.

Figure 4 shows the relationship between head travel and tape travel. The dashed line represents the running trajectory of the head when the tape is running in the opposite direction to the tape running direction, that is, the case of the forward direction (DF) described above. , respectively, represent the running locus of the head moving in the same direction as the tape running direction, that is, the case of the above-mentioned opposite direction (Dm). It can be seen that although the angle and length of the track vary depending on the direction in which the tape runs, 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 L channel acoustic signal are supplied, respectively, and these signals are sent to a line amplifier f() that performs signal level conversion and impedance conversion. 3) and (4)
are supplied to one input end of the adders (5) and (6) through the respective 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 generation circuit (7) is a circuit that generates noise in order to suppress the generation of high-order distortion due to quantization when the signal level is small. The output signals of adders (5) and (6) are:
The sample and hold circuit (g) and αIK are supplied through low-pass filters (8) and (9) for preventing illegal aliasing, which causes a type of distortion in the fundamental wave. The signal sampled and held by the nangle hold circuit (6) and the α poison is supplied to the converter (to) K via the multi-receiver TAS. Here, the sampled analog signals are converted into codes and digital signals corresponding to the respective sample values, and then written into the next stage storage device, for example, RAM (L→RAM.
The signal from ◆ is read out after a predetermined time and redundant pits for error detection and error correction are carried out in the next stage correction code adding circuit (to) to correct code errors that occur during playback due to dropouts, etc. can be added. The output signal from the additional circuit (b) is Y-modulated in the modulator and then supplied to the Q field of the rotating magnetic head on the recording side through a recording amplifier, and is sent to a recording medium such as a tape as a PCM signal (not shown). recorded.

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 rotating magnetic head (2) of the reproduction support is supplied to the Y demodulator (2) via the reproduction amplifier (E), where it is demodulated and then sent to the correction circuit (2). At this point, code errors caused by dropouts or the like are corrected. Furthermore, storage devices such as RAM @
The time axis of the digital signal, which had been compressed during recording, was expanded in the time axis.The digital signal was then converted into an analog signal in the converter (incorporated).
The output signal of the /A converter is
, the L channel signal and the L channel signal are divided and supplied to the line angles ■ and 4 through the low/fourth filter (2) and -, so that the output terminals of the output terminals The original L channel and L channel audio signals are extracted.

This configuration is the configuration of the raw side of a commonly used PCM0M chip recorder.In the present invention, as described above, the time axis of the information of one field is compressed to about half according to the forward and reverse directions of tape running. It is necessary to record it, so for example 500
The frequency of the reference oscillator (a) generated at kHz is divided to 1/10 by the frequency divider (to) to obtain a clock signal φ of 50 kHz, and this clock signal φ is used to control the RAM (1◆ The signal supplied from the Y converter (2) is written into the N converter (2).At this time, the same clock signal φ is supplied to the N converter, and the sample hold circuit (converter) and (Li are Zhou S
In (b), the signal φ· which has been further frequency-divided by lAK is supplied as a nangling signal.

On the other hand, W0◆ is read at a frequency obtained by dividing the frequency of the reference oscillator (2) into 1/4 by the divider (2), that is, 125k.
Readout is performed using a Hz clock signal φm (2,5φ·). As can be seen from FIG. 3, the relationship between the signals φ■ and φ・ is, if the length of the guard track is 36°, the clock signal φ
The frequency of the signal is set to be 2 to 5 times the frequency of the clock signal φ. This signal of φ5 is supplied to the read terminal RK of R''4 through an AND circuit (b). On the other hand, the AND circuit (b) is selectively supplied with a signal corresponding to the forward or reverse direction of tape running. That is,
A forward direction and reverse direction control circuit (b) is provided, and when a forward direction command signal and a reverse direction command signal are supplied from the terminal (to) to this control circuit @, the output side Signals having an opposite phase relationship as shown in FIG. 6C and D are output, respectively. And this signal is the switch circuit -
is supplied as a switching signal. This switch circuit (I4
At the terminal section, there is a vertical synchronizing signal, etc., which is the reference signal for the drum signal at the time of recording.As shown in Fig. signals are supplied. When the tape is traveling in the forward direction, the switch circuit is connected to the contact a side, and a signal as shown in FIG. 6E at the terminal ID is supplied as a control signal to the AND circuit and the switch circuit.

That is, when the supplied control signal is at a high level, the gate of the AND circuit (to) is opened and the switch circuit is closed, and when the control signal is at a low level, the operation is opposite to the above. Therefore, when reading, RAMa♦ is read out by the clock signal φ which is 2.5 times faster than the clock signal φ when writing. As a result, when writing, an information signal as shown in FIG. 6A is stored in RAMα→, but when reading,
A time-base compressed good signal as shown in Figure B is output.

Then, this signal is supplied to the head via the correction code adding circuit as described above, and the time axis is compressed.
The signal is recorded on the tape as the M signal, and in FIG. 2, the signal is compressed on the time axis and stored on the track TF of the tape T.

On the other hand, when a switching signal as shown in Figure 6 is supplied from the control circuit (b) to the switch circuit () based on a signal that instructs the tape running direction to be reversed, the switching circuit (-) switches to the side where the switch circuit (-) contacts. , the signal from the terminal section passes through the contact side of the switch circuit -, is inverted by the inverter, and is connected to the AND circuit (
2) and the switch circuit.

Therefore, in this case as well, the time axis of P is compressed as described above.
A CM signal is recorded on the tape via the head. In other words, in FIG. 2, the signal is compressed in the time axis and recorded on the track TI of the tape T. Furthermore, -
is from the control circuit (b)! Kiya according to the output signal corresponding to the direction of travel! A signal that generates signals to control the Stancer 2 system in forward and reverse directions! This is a stancer Z*+a signal generation circuit.

On the other hand, in the case of reproduction, the switch circuit is controlled by the output signal from the control circuit. That is, when the tape is running in the forward direction, the switch circuit (a) is connected to the contact a side,
On the other hand, in the case of the opposite direction, the contact blI is connected. Also, a control signal similar to the signal shown in FIG. 6E is supplied to the common terminal of the switch circuit () by the terminal (). Therefore, when the switch circuit 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 opens the AND circuit f and the switch circuit opens. When the control signal is at a low level, the operation is opposite to that described above. Further, the clock signal φH obtained as described above, that is, the clock signal having a speed 2.5 times faster than the clock signal φ6, is supplied as a write signal to the other input terminal of the AND circuit.

Therefore, the signal reproduced from the head (to) is transferred to the RAM
The data is written to fi at the same speed as when it is read during recording.

The information written to the RAM in this way is read out by the clock signal φ from the branch (to), and the recorded information is extracted with time axis expansion, and converted into an analog signal by a side converter. After that, as described above, the signal is transmitted to the output terminals - and 0 as L-channel and R-channel acoustic signals via the multi-breather (2) and the like, as described above.

On the other hand, when the vehicle is traveling in the opposite direction, the output signal from the control circuit switches the switch circuit to the contact side, and the control signal from the terminal is inverted by the inverter and then supplied to the AND circuit. At the same time, the power is supplied to the switch circuit θ. Therefore, in this case as well, the signal reproduced by the head is written to the RAM at the same speed as the reading speed during recording, and 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. And R
The signal from AM) is converted to a D/A converter as described above.
output terminal (to) and 0
The signals are extracted as L channel and R channel acoustic signals.

7 to 9 respectively 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, timing is determined in the reverse direction while reading control signals from the control track CTL recorded in advance in the forward direction. 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 CTLF will not be connected to the track in the opposite direction, but if the tape recorder is In such cases, there is no problem.

In addition, in the embodiment shown in FIG. 8, currently, for example, 8 mega pits,
It is difficult to achieve a transmission speed of about 4 gauze, for example, 2 gauze.
This is a case where the PCM signal of 4 megapits is divided into 4 tracks and recorded. That is, in the figure, when the tape T is running in the forward direction (DF), the first signal is recorded on the lower control tracks CTLFI and CTLg of the first fT in accordance with the first and second PCM signals, respectively. do.

On the other hand, if the TEG is running in the opposite direction (Di), the first PC
The M signal and the second PCM signal are recorded on tracks Tll and 'I'll, respectively. Also, the control signals are recorded in the upper control tracks CTL1 and CTLm* on the upper side of the channel fT, respectively.Furthermore, in the embodiment shown in FIG. 9, the normal L channel signal and the R
The channel signals are recorded alternately and continuously within one field, but here the L channel and R channel signals are recorded separately in each direction. That is, in the same figure, Chi! When the tape is running in the forward direction (DF), the L channel signal is recorded on the track TFL and the R channel signal is recorded on the track TFI.On the other hand, when the tape is running in the reverse direction (Da), the L channel signal is recorded on the track TFL. Track signal of channel TIL
and record the R channel signal on track 'I'.
Try to record at 1m. In addition, the control signal is recorded on the control track CTLF at the bottom end of the tape T in the case of the forward direction, and is recorded on the control track CTLF at the bottom end of the tape T in the case of the reverse direction.
so that it is recorded on the control track C'TI4 at the upper end of the file.

As described above, according to the present invention, in a PCM tape recorder that currently can only record in one direction, it is a reverse type that allows the recording medium to run in one direction, forward or backward, and a rotating magnetic head is installed according to the running direction of the recording medium. The structure is such that the signal supplied to the recording medium can be switched, and the signal is recorded on the recording medium in a temporally compressed manner, making it possible to perform back-and-forth recording and improve the pit rate. This makes it possible to record for a long time.

[Brief explanation of the drawing]

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 rounded diagram for explaining the operation of FIG. 5, and FIGS. 7 to #J9 are diagrams showing other embodiments of the present invention. (transition), 01 is the sandal hold circuit, (to) yes humpert, a◆, (2) is RAM, α→ is the modulator, (
(to), (to) is the rotating magnetic head, (to) is the FMS controller, -
is a value converter, (2) is a reference generator, (to), (b), (2) is a branching unit, (2). The ring is an AND circuit, (b) is a forward and reverse control circuit,
H, @, (4, θ is a switch circuit. Fig. 8 Fig. 1

Claims (1)

[Claims] The recording medium is made to run in both forward and reverse directions, and the signals supplied to the rotating magnetic head are switched depending on the running direction, so that the signals are compressed in time axis and recorded on the recording medium. PCM tape recorder.