JPS62112257A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To maximize the reproducing envelope of an ID recording area provided in a time compressed PCM sound signal recording area and to minimize the error rate of address information, etc., on a tape recorded in the ID recording area by controlling tracking at the time of high speed reproduction. CONSTITUTION:When a track locus is considered at the time of the seven times speed, and a speed setting circuit 38 is set to the seven times speed feeding, a magnetic tape 11 is fast-forwarded at the approximately seven times speed, a magnetic head 8 is crossed with a normal reproducing track locus 50 as shown by a seven times speed reproducing track locus 51 and the signal is reproduced. At such a time, when the magnetic head 8 scans an ID recording area 42, the tracking error signal is sample-held, and based upon the tracking error signal, a capstan 39 is controlled. Thus, a reproducing envelope 55 can maximize an ID reproducing envelope 52 in the ID recording area and can minimize the error rate of the address information, etc., on the tape recorded in an ID area.

Description

[Detailed description of the invention] (a) Industrial application The present invention can be summarized as follows: “Nikkei Electronics, 1983
The present invention relates to a magnetic recording and reproducing apparatus according to the 8 m/m VTR standard as described on pages 111 to 124 published on May 23, 2013. Note that the term "magnetic recording/reproducing device" here includes not only devices that have both a recording function and a reproducing function, but also devices that only have a reproducing function; in the latter case, should be understood as a device for reproducing what is magnetically recorded. Furthermore, a magnetic recording/reproducing device based on the 8 m/mV TR standard literally means 8 m/zV.
The term ``TR'' does not only refer to a device such as a PCM audio device, which has a basic mechanical configuration of an 8m/m VTR, but is used exclusively for recording and reproducing audio signals.

(b) Conventional technology Conventionally, four pilot signals for each field are sequentially switched in a certain relationship with the rotation of a rotating magnetic head.
A 1i amount of FM modulated video is recorded on a magnetic tape, and during playback, the pilot signal is extracted and tracked (Japanese Patent Application Laid-open No. 116120/1983). )VTR(
8m/m VTR), a tracking control method has been successfully adopted that focuses only on the video signal and fixes the position of the noise bar on the screen at a substantially constant position during high-speed playback.

(c) Problems to be solved by the invention However, this control method is for fixing the noise bar of the video signal, and the rotation / de takes out the ID signal recorded on the same track as the video signal. In some cases, there is a possibility that the rotary head scans the rD process where the ID signal is recorded across two tracks, and the PCM data is PCM data with no correlation between the two tracks.
There are cases where it becomes impossible to reproduce the D signal.

(d) Means for solving the problem In the present invention, a tracking error signal 7748 is generated from a reproduced pilot signal taken out from a rotary head, and the tracking error signal is recorded in an ID record assigned in a time-compressed PCM audio signal recording area. The tape speed during high-speed playback is controlled by sample-holding and comparing at the timing of the blank area.

(E) The playback envelope of the ID recording area provided in the PCM recording area whose operation time has been compressed is optimized, and the error rate of the ID signal during high-speed playback is minimized.

(f) Embodiment In FIG. 1, the magnetic tape (11) is the capstan (3).
9) and runs in the magnetic tape running direction (17). This capstank 39) is rotationally driven by a capstan motor (35). On the other hand, two magnetic heads (8) attached to the cylinder (9) at a distance of 180 degrees from each other are connected to a cylinder motor (16
) to rotate in the rotation direction (10) indicated by the dotted line arrow. This cylinder (9) is attached to a rotating shaft inclined with respect to the longitudinal direction of the magnetic tape (11), and can be rotated at a frequency of 1 of the vertical synchronization signal of the recorded video signal.

Also, the magnetic tape (11) is 2
It is wrapped over a length of just over 21''. Therefore, the magnetic head (8) alternately scans the magnetic tape (11) in a diagonal direction from bottom to top, and records the PCM time-compressed audio signal and video signal in units of respective tracks.

First, during recording, the video signal (Sl) and the PCM time compressed audio signal (S2) are switched for each area to be recorded.Switching is performed by the switch F-(3), and one of the signals to be recorded is selected by the pilot signal generation circuit. The pilot signal generated in step 4) is amplified by the adder circuit (5), amplified by the amplification circuit (6), and then supplied to the magnetic head (8) via the rotary transformer 7) to generate the magnetic signal. Recording is completed on the track on the tape (11). As shown in Fig. 3, this pilot signal is f+-6, 55H, 52-7, assuming that the horizontal synchronization signal frequency of the video signal is 5H.
, 55, 53-10, 59, 5+-9, 5+, respectively. In addition, the switch 3) is the P shown in Figure 2.
It is switched at the boundary point between the CM time compressed audio signal recording area <41> and the video signal recording area (40). In other words, the magnetic tape (
1]) is 221' in order to record the PCM time compressed audio signal recording area (41) and video signal recording area (40) on the same trunk by wrapping it over 221'.
There is a period when both of the two magnetic heads (8) are in contact with the magnetic tape (11).Thus, although not shown, in reality, the switch (3), the adder circuit, and the amplifier circuit (6) It is needed independently for each of the two magnetic -\/do (8).

The four-frequency pilot signal is set as above, 'r+,
The frequencies of these pilot signals, which are sequentially superimposed on the PCM time-compressed audio signal or video signal and recorded as 5z, 53, and 54, are transferred to a low frequency that is not affected by the video signal. Therefore, when the magnetic head (8) is scanned over the recording track during reproduction, it is possible to extract not only the pilot signal on the track that is being correctly scanned, but also the pilot signals from the adjacent tracks on both sides. By detecting the reproduction level of the pilot signal from the adjacent track, it is possible to obtain an accurate tracking error signal that includes the direction and magnitude of the trunking shift.

Next, the operation during playback will be explained. In Fig. 1, the rotational phase of the magnetic head/de (8) is detected by the PG coil (18), and this detection No. 13 is sent to the phase y4 adjustment circuit (12), which outputs the head phase detection signal and the reference signal. A phase comparator (14) compares the phase of the magnetic head (8) with the reference signal (S, ).In this case, by selecting the frequency of the reference signal (S3) approximately equal to the frequency of the vertical synchronization signal of the recording video signal, the rotational speed of the magnetic head (8) can be set at a constant speed during recording. By controlling the running of the magnetic tape (11) with the tracking error signal while the magnetic head (8) is rotating at a predetermined speed as described above, it is possible to reach the desired recording track Z. Tracking control is performed so that the magnetic head (8) scans accurately.

Next, the operation of tracking control will be explained. First, the rotational speed of the capstan (39) is detected by the FG coil (36), this detection signal is converted to a speed detection voltage proportional to the rotational speed via a frequency discriminator (37), and this voltage is applied to the speed setting circuit. By supplying the capstan motor (35) via the adder circuit (33) and the motor drive circuit (34), the speed is controlled so that the gear stan (39) rotates at a predetermined speed. . Further, the signal reproduced from the magnetic tape (11) by the magnetic head (8) is transmitted through the rotary transformer (7) to the amplification circuit (
20) and the width can be increased. This amplified signal is stored in the PCM time compressed audio signal recording area (41
) and the video signal recording area (40) with the switch/hook (23), the PCM time compressed audio signal and video signal are separated, and the video signal becomes a reproduced video signal via the video demodulation circuit (21). In addition, the PCM time compressed audio signal is
It becomes a reproduced PCM time audio signal via the M demodulation circuit (22). Although not shown, as mentioned earlier, there is a period when both magnetic heads (8) are in contact with the magnetic tape (11), so in reality, the amplification circuit (20), switch (
23) is required independently for each of the two magnetic heads (8). The signal amplified by the amplification circuit (20) is also
It is also sent to the tracking error signal generation circuit via the low-pass filter (24). Low pass filter (24)
Only the pilot signal is separated and extracted. 4
The frequency of the pilot signal is 5 + = 6.55M
,'r 2-755H,'r3-10.55.5 key 9
．． Since it is set to 5f+, when recording 'r+, if the tracking shifts to the right when scanning the track where the 5 copilot signal is recorded, IJ+-521-Irr: + 5+
If the l-5H component increases and shifts to the left, 151; 4! −
IJ: +-521-35M component increases. Also, when recording f2
．． When scanning a track on which the f+pyro//t signal is recorded, if the tracking shifts to the right, l5z-f31-1
If the 5+-511-35+ component increases and on the other hand shifts to the left, lf
:z Jl 1-15- f31-fH component increases. Therefore, in Fig. 1, a pilot signal having the same frequency as the video track to be scanned is also generated during reproduction, and this pilot signal and the reproduced pilot signal are sent to a mixer circuit (26) consisting of, for example, a double-balanced modulator. The output is a signal having a frequency that is the difference between the frequencies of the above two signals, that is, 5
Synthesis No. 48 of component H and three components is obtained. Next, from this composite signal, 9 components and 3JH components are separated by a bandpass filter (27>(2g)), and then an envelope detection circuit (29) is used to convert them into voltage signals with values corresponding to their amplitudes, and then a comparator By extracting the difference component between the two using (30), a difference voltage of 58 components and 3 components is obtained as the output.
represents the level difference between pilot signals detected from adjacent tracks on both sides of the track to be scanned.
This signal becomes a tracking error signal. In the normal playback state, the sample hold switch (31) is in the closed state, and the above-mentioned tracker signal is added by the speed detection voltage and the adder circuit (33), and the motor drive circuit (
34) to the capstan motor (35>), the capstan motor (35) is vibrated and the capstan (39) is rotated so that the magnetic head (8) scans a desired track. As an example of high-speed playback, considering the trunk trajectory at 7x speed shown in Figure 4, if the speed setting circuit (38) in Figure 1 is set to 7x forward speed, the magnetic tape (11) will be fast-forwarded at approximately 7x speed. The magnetic head (8) intersects the normal reproduction track locus (50) and reproduces the 1st number, as shown by the 7x speed reproduction track locus (51) in Figure @4.
As shown in FIG. 5, at the time when the \/do (8) scans the ID recording area (42), the sampling pulse (54) obtained from the RF switching pulse (53) obtained from the PG coil (18>) When the tracking error signal is sampled and held and the capstan (39) is controlled based on this trunking error signal, the playback envelope (55) shown in FIG. Therefore, the error rate of address information, etc. on the tape recorded in the ID area can be minimized. The switch that performs sample and hold is the sample and hold switch (31) in FIG. 1, and it is controlled by the sampling pulse (54). During the sampling and hold period, the sample and hold switch (31) is closed, and the tracking error signal is transferred to the hold capacitor (32). ), the sample and hold switch (31) is opened outside the sampling and hold period, and the capstan (39) is controlled by the tracking error voltage charged in the hold capacitor (32).

The pilot signal 25) applied to the mixer (26) together with the playback pilot No. 18 is also generated in a preset order according to the speed number and the running direction of the magnetic tape (11) during high-speed playback.
The order is +-53=52-5I, but when performing vertical feed at 9x speed, the order is 51-52=5:1-54. When using the ID data, for example, to perform automatic cueing, it is not necessarily necessary to look at the playback screen. Therefore, it can be said that there is no problem even if the number of noise bars on the playback screen increases when trunking is performed based on the ID recording area as in the present invention. Note that it is also possible to cut the playback screen and search at a higher speed.

(G) Effects of the Invention By performing tracking control during high-speed playback according to the present invention, the ID recording area provided in the time-compressed PCM audio signal recording area can be re-worked to a maximum. This makes it possible to minimize the error rate of address information, etc. on the tape recorded in the ID recording area.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a magnetic recording/reproducing apparatus according to the present invention. Figure 2 shows the track pattern diagram during normal playback, Section 3 shows the frequency distribution diagram of the pilot signal, Figure 4 shows the track pattern diagram during 7x speed playback, and Figure 5 shows the timing and envelope waveform. It is a diagram. (11>...magnetic tape, (31>...sample hold switch, (32)...hold capacitor,
(35)... Kihe Bustan Motor, (39)...
・Capstan, (40>...Video signal recording area, (
41)...PCM audio signal recording area, (42)...
ID recording area, (52>...ID playback envelope, (54)...sampling pulse.

Claims (1)

[Claims] (1) A magnetic recording and reproducing apparatus according to the 8m/m VTR standard, characterized in that it is provided with means for performing capstan servo control using a tracking control signal obtained during an ID period in a PCM recording area.