JPH0468831B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a magnetic recording/reproducing device.

Structure of conventional example and its problems Figures 1 to 3 regarding conventional magnetic recording and reproducing device
This will be explained using figures. FIG. 1 is a circuit block diagram of a conventional magnetic recording/reproducing device, in which 1 is an R head (58 μm head), 2 is an L head (58 μm head),
3 is L' head (70 μm head), 4 is L'' head (70 μm head), 5 is PG coil, 6 is rotary transformer, 7 is R head amplifier, 8 is L head amplifier, 9 is L' head amplifier, 10 is L'' 11 is a head switch amplifier, 12 is a central processing unit (hereinafter referred to as CPU), 13 is a normal head changeover switch, 14 is a special playback head changeover switch (hereinafter referred to as SS head changeover switch), and 15 is an envelope changeover switch. , 16 is
FM demodulation circuit, 17 chroma demodulation circuit, 18 chroma reproduction reference signal circuit, 19 mixing circuit, a
is a head switch signal, b is an envelope switching signal, c is a color rotary switching signal, and d is an envelope. FIG. 2 is an explanatory diagram of the installed state of the head, in which 24 is a rotating cylinder, 25 is a tape, and 26 is a post.

R head 1 and L head 2 are used for FWD 1x speed playback, otherwise L' head 3 and L'' head 4 are used.R head 1, L' head 3 and L
The head 2 and the L'' head 4 are arranged adjacent to each other (for example, 2 horizontal periods = 2H).When considering the time of fine throw in the feed direction in intermittent feed fine throw, the output of the envelope is as shown in FIG. In Fig. 3, e is the cylinder reference signal (vertical synchronization signal VSS), f is the head switch signal (for head amplifier switching), g is the carbstan motor drive signal, h is the envelope switching signal, i
is the color rotary signal, j is the envelope, k
1 is a control pulse, 1 is an envelope drop part due to the normal head, 2 is an envelope drop part due to a normal head, 3 is an envelope switching field, and 2 is a fine slow drive period.

Signals from heads 1 to 4 are applied to amplifiers 7 to 10 via rotary transformers 6, respectively, and the video FM signal and low frequency converted chroma signal detected from tape 25 are amplified. The signals from the amplifiers 7 and 8 are switched to the envelope side of the tape-touched head by a head switch signal a whose waveform is shaped by a head position detection signal obtained in synchronization with the rotation of the rotary cylinder 24. At normal FWD 1x speed, the envelope selector switch 15 is set to the normal head selector switch 13 side, and at still (pause) and high-speed playback.
It is switched to the SS head changeover switch 14 side.
The FM signal is demodulated by the FM demodulation circuit 16.
The chroma demodulation circuit 17 converts the low frequency converted chroma signal to a normal 3.58MHz signal. These signals are mixed by a mixing circuit 19 and output as a video.

During reverse intermittent feed (reverse fine throw), the rotary cylinder 24 rotates using the cylinder reference signal e as a reference so that the head switch signal f becomes as shown.
Consider the envelope of the envelope switching field during the fine throw drive period. SS head 3 as well as style (pose),
When selecting playback output No. 4, the envelope output is as shown in FIG.

Figure 3j shows the envelope when embedding is performed by normal head 1 using the envelope switching signal h and color rotary signal i shown in Figure 3.
Shown below. At this time, the envelope falls as shown in A and B. In other words, noise appears at the top or bottom of the screen. This is because the normal head 1 that performs embedding has the same track width on the format. The reason why they are the same is to prevent image quality deterioration due to crosstalk caused by detection of FM signals of adjacent tracks and low-frequency conversion chroma signals during FWD 1x speed (normal recording/playback). The contents of the trace are as shown in FIG. FIG. 3K shows a control pulse detected from the tape 25 during fine throw, and determines the stop position of the tape 25.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and an object of the present invention is to provide a magnetic recording/reproducing device that can reduce the amount of noise on the screen during the drive period during reverse fine throw.

Structure of the Invention In order to achieve the above object, the magnetic recording and reproducing apparatus of the present invention has two normal magnetic recording and reproducing apparatuses with different azimuths, which have the same head width as the track width and are mounted on a rotating cylinder with an interval of 180 degrees from each other. a playback head, and two heads having a wider head width than the normal playback heads, having the same azimuth as one of the normal playback heads, spaced apart from each other by 180°, and mounted on the rotary cylinder at a position near the normal playback head.
When using special playback heads and intermittent playback in the reverse direction,
This configuration includes embedding means for embedding the envelope of the normal reproduction head in the envelope missing portion of the second or third field of the head switch timing during the capstan motor drive period.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, the configuration of the head mounting is the same as that of the conventional example shown in FIG.
Although the configuration is the same as the conventional configuration shown in the figure, the control timing of the envelope switching signal b and the color rotary switching signal c is changed by the CPU 12. Fourth
The figure shows a timing chart of the control contents.
The feature of the present invention lies in the R head envelope embedding section of the envelope switching signal o. This is done by selecting L' head 3, which is a wide head of T ₁ minutes after 2 to 3 fields from the start point during the driving period of the carbstan motor control signal n, and selecting R, which is a normal head (head width same as the track). Head 1
embed in the envelope. Also, embed T ₃ minutes in the same way. For the R head 1 envelope, select only the larger _T2 . These embedded envelopes are the hosts of q. FIG. 5v shows the envelope during this reverse fine throw. 4 corresponds to the wo of FIG. 5.

In this way, there is no dip in the envelope,
It can reduce noise on the screen.

In Figures 4 and 5, l is the cylinder reference signal (vertical synchronization signal VSS), m is the head switch signal, n is the capstan motor control signal, o
is envelope switching signal, p is color rotary signal, q is envelope, r is control pulse, E is L' head envelope, H is R head envelope, G is L' head envelope, 4 is R
The head envelope embedding period, _T1 is the L' head playback period, _T2 is the R head playback period, _T3 is the L'head playback period, s is the head switch signal, t is the envelope without embedding, and u is the entire head switch period. , v is the envelope in one embodiment of the present invention, li is the depressed part of the envelope, nu is the missing part of the envelope due to the normal head, ru is the missing part of the envelope due to the normal head, wo is the L′ head envelope, and wa is the envelope with the normal head. R is the head envelope, F is the L' head envelope, Y is the effective envelope (same azimuth), and T is the invalid envelope (reverse azimuth).

Effects of the Invention As explained above, according to the present invention, it is possible to reduce noise on the screen during reverse fine throw.
You can get beautiful images.

[Brief explanation of drawings]

Fig. 1 is a circuit block diagram of a magnetic recording/reproducing apparatus according to a conventional device and an embodiment of the present invention, Fig. 2 is an explanatory diagram of a state in which a head is attached to a cylinder, and Fig. 3 is an illustration of a backward intermittent feed (fine slow) in a conventional device. ), FIG. 4 is a timing chart of embedding during intermittent forwarding in the reverse direction of a magnetic recording and reproducing apparatus according to an embodiment of the present invention, and FIG. 5 is a timing chart for tracing the tape pattern during intermittent forwarding in the reverse direction. FIG. 1...R head, 2...L head, 3...L' head, 4...L'' head, 5...PG coil, 6...
...Rotary transformer, 7...R head amplifier,
8...L head amplifier, 9...L' head amplifier,
10...L'' head amplifier, 11...Head switch amplifier, 12...CPU, 13...Normal head changeover switch, 14...SS head changeover switch, 15...Envelope changeover switch, 1
6...FM demodulation circuit, 17...Chroma demodulation circuit,
18...Chroma reproduction reference signal circuit, 19...Mixing circuit, 24...Rotating cylinder, 25...Tape, 26...Post.

Claims (1)

[Scope of Claims] 1. The head width is the same as the track width and the head width is the same as the track width.
Two normal playback heads with different azimuths are mounted on a rotating cylinder 180° apart, and one head is wider than the normal playback heads and has the same azimuth as the normal playback head and is 180° apart from each other. two cylinders mounted on the rotary cylinder at intervals and usually in the vicinity of the reproducing head;
When using special playback heads and intermittent playback in the reverse direction,
A magnetic recording/reproducing apparatus comprising: embedding means for embedding the envelope of the normal reproduction head in the envelope missing part of the second or third field of the head switch timing during the capstan motor drive period. 2. The embedding means uses the special playback head to reproduce the depressed portions of the envelope of the normal playback head immediately before and after the head switch timing of the field to be embedded, and reproduces only the central portion of the field where the envelope of the special playback head is missing using the normal playback head. 2. A magnetic recording and reproducing apparatus according to claim 1, wherein the magnetic recording and reproducing apparatus is configured to carry out embedding.