JPS58133611A - Recorder and reproducer - Google Patents

Abstract

PURPOSE:To attain correct reproduction at all times even if tape jitter takes place, by making the windth of window detecting sound signals at reproduction broader than the sum of the recording part of the sound signal at recording and the tape jitter fluctuating. CONSTITUTION:To prevent adverse effect of noise, in conventional systems, a window signal equal to that at recording is applied to a PCM demodulation/ time axis expansion circuit 19 and the circuit 19 is driven only during this signal. In this invention, to the window signal at recording, a window signal at reproduction as expressed in figure A is widened by alpha each to front and rear part as expressed in figure B. The value of alpha is larger than the maximum value of the jitter portion beta. Thus, in this device, even if jitter exists in a reproduced PCM signal as expressed in figure C, the circuit 19 is driven during the period of the PCM signal and correct reproduction is performed. Even if there is more or less noise at the front and rear part of the PCM signal, it is no problem because the demodulation is performed after the synchronizing signal at the beginning of the PCM signal at the circuit 19.

Description

[Detailed Description of the Invention] A so-called helical scan type video tape recorder (
In VTRs, the tape is wound around the rotating drum by making the angle larger than the angle of the head, providing an overlap period in which multiple heads are in contact with the tape at the same time, and during this overlap period, at least one head is in contact with the tape. Te PCM
It has been proposed to record encoded audio signals.

FIG. 1 shows an example of such a device. In the figure, Kazuko (1) K is supplied with an Eirin signal to be recorded, and this Eirin signal passes through a processing circuit (2;, an amplifier (3)) and a switch (
4), one of the fixed contacts v [supplied in (5).

In addition, the terminal (6) K is supplied with an audio signal to be recorded, and this audio signal is sent to the PCM one-time axis compression circuit (7), the amplifier (
8) to the other fixed contacts aVc of the switches (4) and (5).

The signals obtained at the movable contacts of these switch 7 (41, (!5)) are respectively supplied to the fixed contact rK on the recording side of the switch (9) and α.@And these switches (9)
.

The arm numbers obtained at the movable contacts of QQ are supplied to heads αυ and α provided on the rotary head device, respectively, and the tape'
rK device.

Here, the heads αυ and α are provided at an angle of 180 degrees, and the tape T is wound over an angular range of 220 degrees. In addition, the transfer of the tape T and the head aυ, a
Although not shown, the rotation servo of the hot water is performed by a conventionally known method using a CTL signal, a pulse generator, the output of a timing generation circuit to be described later, and the like.

Also, the tape T is played back by heads a1) and Q3, and the nine polarizations are respectively switched to switches (9) and (1G movable contact A).
VC is supplied. And these switches (9),
The playback signal is taken out from the fixed contact p of the playback side of Q (I) @these switches (9), (the playback signal from IQ is taken out from the fixed contact p of switch a, α4, fixed contact o,
Supplied to @. The signal obtained at the movable contact of the switch a is taken out to the video signal output terminal (+7) through the amplifier 09 and the processing circuit Qe. Further, the signal obtained at the movable contact of the switch I is taken out through the amplifier CI8 and the PCM demodulation/time axis expansion circuit 09 to the audio signal output terminal (2).

Furthermore, a clock oscillator ■ is provided, and this oscillator (2)
A clock signal from the counter @ is supplied to the counter @. In addition, the vertical synchronization signal from the recording side processing circuit (2) is switched (
) is supplied to the fixed contact rK on the recording side, and this switch (
The signal obtained at the movable contact (to) is supplied to the reset terminal of the counter (2). The count value of this counter (support) is supplied to the timing generation circuit axis consisting of a decoder etc., and the signals from this generation circuit axis are used to switch the various parts (
4), (5), etc. are controlled. Also, the generation circuit
A signal corresponding to 60 Hz is supplied to the fixed contact PK on the reproduction side of the switch (2).

Furthermore, in FIG. 2, which shows a time chart of this apparatus, when recording a square, a vertical synchronizing signal as shown in the figure is supplied to a counter@, and this count value is supplied to a tie generation circuit. The servo system is driven by the signal from this generation circuit (E).Heads aυ and αa are respectively B.

The tape TK is brought into contact with the tape TK in the range indicated by CVc. Further, the window signal shown in D is supplied to the PCM/time axis compression circuit (7)K, and the audio signal corresponding to the length of any one vertical period before that is converted into PCM and taken out.Furthermore, a switch (4), (As shown in E, it is switched in opposite phases to each other in one vertical period. Note that the switch (9).

(II, @ has switched contact rllK.

As a result, when recording, for example, the tape TK! During the first overlap period of WII, the PCM signal is supplied through the contact layer of the switch (4), and the following one
During the vertical period, a video signal is supplied through the contact V of the switch (4) and recorded on the tape T. In the same way, head QaK is supplied with the next PCM' signal and video signal and recorded on tape T.

Further, FIG. 3 shows the recording track pattern on the tape recorded in this manner. In the figure, the recording tracks are formed sequentially from the left side of the figure, and each track is recorded from the bottom to the left side. Then, in each track, a PCM' audio signal and a partial pressure video signal are recorded in the area where the area has been formed.

Also, during reproduction, a 60 Hz signal is supplied to the counter@, and this 6ong signal is equivalent to the vertical synchronization signal shown to the human body. Therefore, the servo system is driven in the same manner as during recording. Further, at the timing E mentioned above, the phases are switched to be opposite to each other.

Note that the switches (91; 01, fi are switched to the contact p side).

As a result, during playback, the signals reproduced by the heads 0υ and α are taken out alternately every vertical period by the switches Q:l and (+4), and the Eirin signal is taken out continuously from the switch Q:l and (+4), and Switch 04) Gara P
The CM signals are sequentially extracted, and the above-mentioned window signal D is then PCM demodulated.
The time axis expansion circuit alK is supplied, and the P supplied during this time
An audio signal having a length of one vertical period is demodulated from the CM signal.

In this way, recording and reproduction of the video signal and the audio signal are performed.

By the way, in this apparatus, a PCM signal is taken out from switch a4 as shown in Fig. BK.A indicates the above-mentioned 60 Hz signal'.Here, the head is separated from the tape during periods other than the PCM signal.

For this reason, a normal reproduction signal cannot be obtained, but leakage of the reproduction signal from the other head and other noises are superimposed. If such noise is supplied to the PCM demodulation/time axis expansion circuit a, it will cause malfunction and adversely affect the subsequent demodulation, etc. Therefore, in the above-mentioned device, the window signal ( A window signal equivalent to that shown in FIG. 3D) is supplied to the circuit 09, and the circuit 09 is driven only during the period of this G window signal.

However, in the above-mentioned apparatus, so-called tape jitter occurs due to expansion and contraction of the tape, malfunction of the tape running system, etc., and the timing of the reproduction signal changes. That is, in FIG. 5, when the contact position of the head 0υ shifts in the tape running direction, the timing of reproduction No. 41 from the oblique track changes. This causes a time variation of, for example, ±β in the timing of the PCM signal.

For this reason, in the above-mentioned apparatus, if playback is performed using a window signal with the same timing as recording, if jitter occurs as shown on the right side of FIG. Correct playback will no longer occur.

In view of these points, the present invention is designed to ensure that correct playback is always performed with a simple configuration. An embodiment of the present invention will be described below with reference to the drawings. In the present invention, with respect to the window signal at the time of recording shown in FIG. Expand: Here, the value of a is set to be larger than the maximum IO value for jitter.

Therefore, in this device, even if there is jitter in the reproduced PCM signal as shown in C, the circuit a during the period of this PCM signal
Yu is driven and the correct reproduction takes place.

Note that even if there is some noise before and after the PCM signal, there is no problem because demodulation is performed after the synchronization signal at the beginning of the PCM signal in the circuit a.

In addition, in order to form window signals during playback with different timings, the decoding values of the self-selected decoders in the timing signal generation circuit (c) are changed, but decoders with different values can be switched and used. In this case, the switching timing of the switch (13, H) may be slightly delayed so as to coincide with the trailing edge of the window signal.

In this way, video signals and audio signals are recorded and played back.According to the present invention, the window signal when recording and playing back the audio signal by converting it into PCM is made wider during playback than during recording, thereby eliminating tape jitter. Correct playback can always be performed even when this occurs.

In the present invention, the configuration for converting the audio signal into PCM and recording it during the overlap period is not limited to the example shown in FIG.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams for explaining the recording/reproducing device;
FIG. 5 is a diagram for explaining a conventional device, and FIG. 6 is a diagram for explaining the present invention. fll, +61 is an input terminal, (power is a PCM/time axis compression circuit, (17), +211 is an output terminal, O9 is a PCM demodulation/time axis expansion circuit, and trout is a timing signal generation circuit.

Claims (1)

[Claims] It has a rotating head device, wraps the tape in an area larger than the angular division of the heads to provide a period in which a plurality of heads are in simultaneous contact with each other, and during this period, at least one head transmits a PCM audio signal. In the recording/playback device configured to record, the width of the window for detecting the audio signal during playback is made wider than the sum of the recorded portion of the E audio signal during recording and the jitter variation of the tape. A recording/playback device characterized by: