JPS6057569A - Rotary head type magnetic recorder and reproducer - Google Patents

Abstract

PURPOSE:To transmit with fidelity a recording digital signal without giving any disturbance to an analog signal and with a low code error rate by installing an attenuator to the input side of a transmission line in the transmission system of the recording digital signal and a limiter circuit to the output side and eliminating the transmission waveform distortion of the digital signal. CONSTITUTION:A sound signal A inputted from a terminal 6 is outputted as a PCM sound signal B after it is PCM-modulated by means of a PCM processor 10 and time base compressed. The PCM sound signal B is inputted into the attenuator 12 and, after its amplitude level is attenuated, transmitted through a transmission cable 20 where its waveform is rounded because of transmitting band limitation by the stray capacity, etc., of the cable 20. When the transmitting rounded PCM sound signal C is supplied to a limiter circuit 35 through a capacitor 30 for AC coupling and subjected to amplitude limitation around the amplitude intermediate value level at the circuit 35, the PCM sound signal B' before transmission can be restored.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention sequentially and continuously records analog recordings on parallel helical scan recording tracks sequentially formed by a plurality of rotary heads, and also records the overlapping recording portions. Rotation that uses digital signals to be inserted and recorded intermittently.

The present invention relates to a magnetic recording/reproducing device.

[Background of the invention]

The above-mentioned rotary head type magnetic recording/reproducing device records, for example, FM-modulated video signals sequentially and continuously on helical scan recording tracks, and also records PCM-modulated and time-axis compressed bursts in the overlap recording portion. A rotary head type video tape recorder has already been proposed which records audio signals by intermittently inserting them. First, all such conventional examples will be explained using FIGS. 1 to 4.

FIG. 1 shows a pattern of helical scan recording tracks recorded and formed on a magnetic tape 1. Each helical scan recording track P is formed by moving the magnetic tape 1 running in the direction of arrow X, as is well known, by two rotating heads. are formed by sequentially and alternately rotating and scanning in the direction of arrow Y. In this case, before one rotary head finishes forming a recording track, the other rotary head comes into contact with the magnetic tape 1 and starts forming the next recording track, and both rotary heads simultaneously overlap for a predetermined period of time. Therefore, during this overlap JtJ, one rotary head, for example, the one that starts forming a new recording track, is given an FAI modulated video signal. On the contrary, if the entire time of the PCM audio signal is compressed and then switched and supplied, the scanning section t of the helical scan track P that is sequentially formed.

1? While recording the M video signal temporally continuously, the time-compressed pcxt audio signal can be inserted and recorded intermittently in the scanning section t1.

FIG. 2 α and b are reproduced waveforms obtained by alternately rotating and scanning the helical scan recording track Pf recorded with the track pattern shown in FIG. 1 with two rotary heads. 2.3 is FAI modulated video signal, 4.5
is a time-base compressed l) CM audio signal. The FM modulated video signal 2°6 is alternately reproduced by two rotary heads in each interval t2 shown in FIG. Extracted as a signal.

The PCM audio signals 4 and 5 are alternately and intermittently reproduced by two rotary heads every interval t in FIG. After, P
CIf demodulation is performed to restore the original temporally continuous analog audio signal.

Figure 5 shows an FM modulated video signal and a time-base compressed PC using the helical scan recording track pattern shown in Figure 1.
FIG. 4 is a block diagram showing the configuration of a recording circuit for recording M audio signals. FIG. 4 is a diagram showing the operating waveforms of each part, and signals corresponding to FIG. 6 are given the same symbols. . In FIG. 6, 6 is an input terminal for an audio signal A, 7 is an input terminal for an FM modulated video signal, 8 is an input terminal for a head switching position control signal F, 10 is a PCY processor, 20 is a transmission cable, 30 .31 is an AC coupling capacitor, 40.41 is a changeover switch, 50 is an inverter, 51.52 is an AND circuit, 60.61 is a recording amplifier, 70.71 is a rotary head, and 80 is a magnetic tape.

Ward 3 1. In FIG. 4, an audio signal A input from a terminal 6 is PCM modulated by a PCM processor 10, compressed on the time axis, and output as a burst FCM audio signal B. The period during which the burst-like PCM audio signal B is generated is controlled as appropriate so that the rotating heads 70 and 71 overlap and scan the magnetic tape 80, that is, the scanning in FIG. 1 coincides with the interval t. shall be.

The PCJ (audio signal B is waveform-transmitted by the transmission cable 20, and the transmitted PCPR audio signal C is supplied to the respective terminals 'Is'k of the changeover switches 40 and 41 via the AC coupling capacitor 60. On the other hand, the FM modulated video signal inputted from the terminal 7 is supplied to each terminal 'I+G of the changeover switch 40 and 41 via the AC coupling capacitor 61.The changeover switch a
o, 41 are controlled by switching control signals G, H(1') shown in FIG.
Only during the high level of the switching control signals G and H, the pcu audio signal C is supplied to each terminal 'I+terminal C7 side, and during the low level period, the I'M modulated video signal is supplied to each terminal. The terminal dle is switched to the terminal d side. Switching control signals G and E for performing such switching are generated in the following manner based on the head switching position control signal F inputted from the terminal 8 and the gate signal E outputted from the PCM processor 10. That is, the gate signal E is a signal generated corresponding to the generation period of the burst-like PCM audio signal B, and as described above, the pCu audio signal generation period corresponds to the scanning of the recording track shown in FIG. Since the period t corresponds to the period during which the rotating head 70.71 scans, the gate signal E also corresponds to this, and the rotating head 70.71 corresponds to the scanning period of the recording track shown in FIG. The gate signal E is generated every period when t is sequentially scanned, and the gate signal E is supplied to one input terminal 'Ie'2 of each of the AND circuits 51 and 52. On the other hand, the head switching position control signal F has a data ratio of 5 which is synchronized with the rotational phase of the rotary head 70.71.
It is a 0% rectangular wave signal, and its polarity is at a low level during the period in which the rad 70 is scanning one rotation of the scanning section t1 of the recording track shown in FIG.
f is set to a high level during the period when the other rotary head 71 is scanning, and the head switching position control signal is supplied to the other input terminal f of the AND circuit 52 and , and is supplied to the other input terminal Lvc of the AND circuit 51 via the inverter 50. Therefore, if the rotary head 70 is currently scanning the scanning section '+' of the recording track shown in FIG.
The signal supplied to the input terminal f1 of the AND circuit 51 via 0i is at a high level, and on the other hand, the gate signal E supplied to the input terminal et of the AND circuit 51 is also at a high level. 40 to terminal C1
A switching tllll@signal G is output to switch to the side.

The rotating head 71 scans the scanning section 1 of the recording track shown in FIG. If b7S is scanned (C, since the head switching position control signal @F is at a high level, both high level signals are supplied to the input terminals '2+J'2 of the AND circuit 52, and therefore The AND circuit 52 outputs a switching control signal H that switches all terminals of the changeover switch 41 to the C2 side.By switching the changeover switches 40 and 41 using these changeover control signals G and H, the output of the changeover control signal is output. period, i.e. rotating head 7
0.71 scans the scanning section t1 in FIG. 1, the PCB audio signal is switched and inserted instead of the FAI modulated video signal. Since J is obtained, the signal I.

Jfz recording end 60.61 then rotating head 70.7
1, it is possible to intermittently insert and record a PCAI audio signal into an FM modulated video signal in a track pattern as shown in FIG.

By the way, such a conventional rotary head type magnetic recording/reproducing device has the following drawbacks.

(b) When the PCM audio signal output from the PCM processor 10 is transmitted by the signal transmission cable 20, the transmission band is limited by the stray capacitance of the transmission cable 20, so the transmission waveforms are crowded and the size is small. However, there is a mismatch between the output impedance of the PCM processor 10 and the characteristic impedance of the transmission cable 20, and furthermore, the transmission cable 20
The characteristic impedance of and the output end of the transmission cable 20 (
(Reflection occurs due to mismatching of M impedances and waveform distortion occurs in the transmitted fCM audio signal, so the code TFI error increases, making it impossible to reproduce the correct audio signal and deteriorating the sound quality.

←) The PCM processor 10 is usually CMO5, TTL
In this case, its output P
The CAI audio signal B is a signal with a large amplitude that changes from the power supply voltage level of the PCM processor to the ground level 1. Therefore, the fundamental wave component and harmonic component of the PCM audio signal radiated from the transmission cable 20 are large, and the PCJf audio signal This interferes with the H modulated video signal that is recorded at the same time as the B signal is sent, degrading its image quality.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide an analog signal that is sequentially and continuously recorded on a helical scan recording track by a plurality of rotary heads and is transmitted via a transmission system by utilizing all of the overlap recording portions of the analog signal. A rotating head type magnetic recording system that enables faithful transmission of recorded digital signals by reducing the bit error rate of the digital signals themselves, without intermittent insertion and recording of all recorded digital signals, without interfering with analog signals. To provide playback equipment.

[Summary of the invention]

In order to achieve this object, the present invention provides an attenuator on the input side of a transmission line in a recording digital signal transmission system and a limiter circuit on the output side. An attenuator is provided to reduce the level of interference waves to all analog signals of the digital No. 46 propagating throughout the transmission line, and a limiter circuit is used to completely eliminate distortion of the transmitted waveform of the digital signal due to the transmission line. DESCRIPTION OF THE PREFERRED EMBODIMENTS [Examples of the fruits of the invention] Examples of the present invention will be described below with reference to the drawings.

FIG. 5-1 A block diagram showing an embodiment of the recording circuit for the rotary head type magnetic recording/reproducing apparatus 1 according to the present invention. FIG. 6 shows the transmission waveform of the recording digital signal transmission system. 5, in which signals corresponding to those in FIG. 5 are given the same reference numerals. The embodiment shown in FIG. 5 has an attenuator 12 on the input side and an IJ transmitter circuit 3 on the output side of the conventional transmission cable 20 shown in FIG. The other 41/ν components are the same as the conventional f11 shown in FIG. 3, and the same components are given the same symbols as in FIG. 4
Details are omitted.

To explain the operation of the embodiment shown in FIG.
The signal is CM modulated, compressed on the time axis, and output as PC, M audio code B. PCM audio signal, attenuator 1
2((After being input and having its amplitude level attenuated, it is transmitted through the transmission cable 20. FIG. 6B' shows the waveform of the attenuated PCM audio signal.The transmitted PCXR
Due to the transmission band limitation due to stray capacitance of the audio signal C signal transmission cable 20, the waveform is distorted, and the mismatch between the output impedance of the attenuator 12 and the characteristic impedance of the transmission cable 20, and the characteristics of the transmission cable 20. Reflection occurs due to a mismatch between the impedance and the load impedance at the output end of the transmission cable, and waveform distortion occurs in the transmitted PCM audio signal C. FIG. 6 C1 shows that the waveform has one pcM due to the transmission band limiting characteristic of the transmission cable 20.
In the waveform diagram of the audio signal, 1, 62 in FIG.
FIG. 3 is a waveform diagram of a CAI audio signal.

However, although the PCM audio signal after transmission is subject to waveform rounding or waveform distortion, the shift l-id on the time axis at the rise and fall of the signal, CI + in Figure 6
As is clear from C2, the amplitudes are almost the same at the intermediate position indicated by the dotted line, and therefore, at the intermediate position of the PCM audio signal amplitude after transmission, II(, 'AI audio
The duty ratio of No. B' is maintained. therefore,
Transmission PCkf audio signal C signal flow coupling well I capacitor 30
The entire supply is supplied to the limiter circuit 35, and the limiter circuit 35
If the amplitude is limited around the intermediate amplitude level of the PCM audio signal, the PCM audio signal f before transmission can be restored, as shown in FIG. 6C'.

Ffii modulation in which the fundamental wave component and daytime harmonic component of the PCM audio signal transmitted by the transmission cable 20 and the attenuator 12 radiate from the transmission cable 20 during transmission are recorded at the same time. It is sufficiently attenuated to the extent that it does not interfere with the video signal. In this case, the S/N of the transmitted PCM audio signal naturally deteriorates, but
Noise components superimposed on the PCM audio signal are removed by the limiter circuit 35, so there is no particular problem.

Now, the 71C, AI sound signal ', which has been waveform-shaped by the limiter circuit 35 and has a sharp rectangular wave, is further inputted to the recording equalization circuit 66 as required. This recording equalization circuit 36,
It converts the I'CAI audio signal into the optimal waveform for recording, such as the Journal of the Institute of Electronics and Communication Engineers Vo L/J64-Ct.
4α11. As described in P762 to P76B, the rectangular wave PCkf signal is converted into a waveform with an automatic shoot. p output from the recording equalization circuit 66
The cm audio signal is sent to each terminal Cr, l? of the switching switch 40°41. 2 is input. On the other hand, the FM modulated video input from terminal 7 is transferred to selector switch AQ and terminal 41 via countercurrent coupling capacitor 31.
It is input to Ie'2. In this embodiment, the recording equalization circuit 36i 1J mitter circuit 55 and the changeover switch 40
．． 41), the PCM audio signal is waveform-shaped by the IJ transmitter circuit 35 and then recorded and equalized. Easy and stable equalization can be performed regardless of the influence of characteristics, and PCM
Optimal recording equalization can be performed for all audio signals.

Each terminal of the changeover switch 40.41'+ +
The PCM audio signals and FM modulated video signals input to '1, C2, and C4 are switched by switching control signals @G and H, as in the conventional example shown in FIG.
, 611. (Feeded to rotating head 70.71 via
The information is recorded on the magnetic tape 80, but the details have already been explained in the VC, so the details will be omitted.

In addition, in the embodiment disclosed above, the digital signal f 1
) The explanation has been made as a time-base compressed PCM audio signal output from the CAf processor 10, and as an FM-modulated video signal as an analog signal, but generally a digital signal is generated from an arbitrary digital signal generation circuit. An analog signal as large as 5 cm may be used, for example, an AJf modulated signal, or an analog signal that can be used as an audio signal, and in either case, it does not depart from the scope of the present invention.

In the above embodiment, a case where a transmission cable is used as a digital signal transmission path is explained, but the present invention is equally applicable to the case where a normal transmission line or a transmission path with a wiring pattern on a board is used. There's nothing you can do.

〔Effect of the invention〕

As explained above, according to the present invention, by providing an IJ transmitter circuit on the output side of the transmission path of the recording digital signal, the waveform distortion of the transmitted digital signal due to the transmission band limiting characteristic of the transmission path, impedance mismatch, etc. Since the data can be recovered, code errors in the digital signal during playback can be significantly reduced.The limiter circuit described above has a gold film, so the recorded digital signal can be transmitted regardless of the absolute value of the amplitude. By inserting an attenuator on the side and sufficiently attenuating the recorded digital signal before transmitting it, will the transmitted digital signal interfere with the analog signal recorded at the same time? You can give it as you like, and if necessary, the above IJ,? By providing a recording equalization circuit on the output side of the vine circuit, it is possible to achieve a
It is possible to provide a rotary head type magnetic recording/reproducing device which has superior functions, such as being able to perform recording equalization optimal for recording digital signals, while eliminating the drawbacks of the prior art.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a pattern of a helical scan recording track recorded on a magnetic tape, FIG. 2 is a reproduction waveform diagram of the helical scan recording track, and FIG. 3 is a diagram of a conventional rotary head type magnetic recording/reproducing device Gt. FIG. 4 is a block diagram showing the configuration of a recording circuit according to the present invention; FIG. 4 is a diagram showing operating waveforms of each part thereof; FIG. , FIG. 6 is a diagram showing the transmission waveform of the recording digital signal transmission system. 10... pcu processor 12... attenuator 20.
...Transmission cable 35...Limiter circuit 36...
Recording equalization circuit 40.41... Changeover switch attorney Akio Takahashi $ 1 Diagram

Claims (1)

[Claims] Analog signals are sequentially and continuously recorded on helical scan recording tracks sequentially formed by M number of rotary heads, and a digital signal transmitted from a digital signal generation circuit via a transmission system is switched to the overlap recording portion. In a rotary head type magnetic recording/reproducing device that records data by intermittent insertion using a means, the transmission system of the digital code is provided with an attenuator on the input side of the transmission line and a limiter circuit on the output side. A rotating head type magnetic recording and reproducing device characterized by: