KR860001014B1 - Helical scan type video tape recorder - Google Patents

Abstract

This apprts. is concerned with helical scan type video tape recorder that has editing capacity. It comprises as follows: 1) Record tracks are formed on the tape with different azimuths 2) the first and second erasing heads, located at position behind the recording heads, which more in rotating direction and are close to each other 3) recording heads having azimuths similar to their erasing heads. In editing, the first erasing head eliminates the track recorded by the second recording head, and the second recording head records, and the second erasing head eliminates the first one, and the first recording head records.

Description

Magnetic recording and playback device

1 is a schematic plan view schematically showing a relationship between a rotary member and a magnetic tape.

2 is a perspective view showing a magnetic head according to the present invention.

3 is a plan view showing the magnetic head of FIG.

4 shows a method of scanning magnetic tape by a magnetic head.

5 is a block diagram showing an embodiment of a magnetic tape editing circuit.

6a to 6k are time difference art for the circuit of FIG.

7 illustrates a method of scanning magnetic tape by a magnetic head when the erase head is positioned behind the video head.

8 shows another embodiment of a composite magnetic head according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helical scan type video tape recorder, that is, a magnetic recording / playback apparatus, and more particularly, to a helical scan type video tape recorder having an editing function.

Conventionally, there has been a two-head helical scan video tape recorder for editing. That is, it has two sets of heads, each set consisting of an erasing head and a video head, wherein the video signal already recorded in the video track is erased by the erasing head before the incoming video signal is recorded. It is installed to scan the magnetic track. However, in such a video recorder, since the erasing head and the video head are mounted on the rotary member at relatively intervals, they can continuously scan the same magnetic track, and the preceding erasing head starts or ends contact with the magnetic tape. In this case, the impact is given to the magnetic tape, which causes a time-base error, a so-called impact error.

In another aspect, in an ordinary videotape recorder for editing, the effective track width of the erase head is larger than that of the video head. Therefore, when such an erasing head and a video head are applied to a guardbandless azimuth recording apparatus, an erasing head having a larger effective track width can erase data recorded in adjacent tracks.

Therefore, the main object of the present invention is to provide a novel videotape recorder of the helical scan type, that is, a magnetic recording and reproducing apparatus.

Another object of the present invention is to provide a novel magnetic recording and reproducing apparatus having an editing function.

It is still another object of the present invention to provide a novel magnetic recording and reproducing apparatus having a rotary or flying erase head.

In the videotape recording (hereinafter referred to as VTR) according to the present invention, the plawang erasing head is provided in the vicinity of each pair of rotary video heads. Each video head has a different azimuth angle, and the recording density is varied by the so-called azimuth recording technique.

Each flying erase head is located at a gap height that erases the preceding track when the combined video head is being recorded.

Preferably, the effective track width of the flying erase head is made equal to or smaller than that of the rotary video head according to the present invention. The selection of the effective width is very important for a VUR employing guidebandless orientation recording.

In order to edit, one track must be reliably erased, and a new video signal must be recorded on the erased track. For this reason, the erase head cannot use a fixed so-called full erase head and so-called flying erase head is required. Therefore, the operation of editing is that when the recording command signal is input, the first erasing head having the first azimuth angle slides the track having the second azimuth angle (referred to as track T ₂ forward), so that track T ₂ Erased. Next, the track and a second erasing head on with the azimuth angle of the second with the azimuth angle of the first as slips (hereinafter referred to a track is referred to as T ₁₎ movements, the track T ₁ is the above at the same time as the erase has a degree of orientation of the second A new video signal is written to the erased track T ₂ by a second recording head attached to a position where the erasing head of 2 is trailing. This operation completes a new recording of one track.

Next, the track T ₁ erased by the second erase head is recorded by the first recording head having the first azimuth angle. At this time, the track T ₂ ′ (another track existing between the track T ₂ and the track T ₁₎ having the second azimuth angle by the first erasing head preceding the first recording head is operated as described above. Is erased by This operation is performed continuously, and the editing is completed. Editing with this configuration leads to the following transitions. That is (1). Since the erase head precedes the write head, the edge portion of the recorded track is not erased by the magnetic flux leaking from the edge of the erase head. (2). Since the erasing is performed with the heads of different azimuth angles, the effect of the erasing signal on the video signal is reduced by the azimuth loss. As described above, excellent editing is possible which is not available in the related art.

The present invention will be described in detail with reference to the accompanying drawings.

1 schematically shows the relationship between a rotary member having a magnetic head assembly and a magnetic tape spirally wound on the rotary member. In FIG. 1, the composite magnetic head 1 for channel A (hereinafter referred to as A head) and the other composite magnetic head 2 for channel B (hereinafter referred to as B head) are rotary members (usually rotary). And a magnetic tape 3 spirally wound at a predetermined wrap angle. The head is spaced apart by about 180 ° at the place of rotation of the rotary member 4. Since the A and B heads 1 and 2 have substantially the same configuration, only the configuration of the A head will be described next.

As shown in FIG. 2, the A head 1 has a recording / flyback head (hereinafter referred to as an R / P head) 5 and a plawang erasing magnetic head (hereinafter referred to as an FE head) 6 These heads are joined by a nonmagnetic material 7 such as glass. In the R / P head 5 and the FE head 6, the parallel gaps 8 and 9 each having a predetermined azimuth angle α are formed as shown in FIG. As shown in FIG. 4, the A and B heads 1 and 2 are continuous A channel recording tracks (hereinafter referred to as tracks A ₁ , A ₂ ...) And B channel recording tracks (hereinafter referred to as B ₁ and B _2). The magnetic tape 3 (in the arrow F direction in FIG. 4) is adapted to be formed by the gaps 8 and 13 of these heads. At this time, as shown in FIG. 3, the effective track width l ₁ of the track scanning direction F formed by the preceding E head 6 is the track scanning direction F formed by the R / P head 5. It is made equal or smaller than the effective track width (l ₂ ) of.

As shown in FIG. 4, the position of the gap 8 formed in the FE head 6 leads the position of the gap 8 formed in the R / P head 5 in the track scanning direction.

The arrangement as shown in FIG. 7, that is, the gap a 'of the FE head a and the gap b' of the R / P head b are formed so that the former attracts the latter in place. The data recorded on the recording track A ₁ by the / P head b, in particular the data portion recorded at the edge of the recording track A ₁ , is a lateral generated in the gap a 'of the FE head a. This excretion is because it is easily erased by the leaker. In the above excretion, the gap 9 of the FE head 6 leads the R / P head 5 in place, so that the recording by the R / P head 5 is carried out by the FE head 6. After erasing. In other words, the erased data is the previously recorded data which appears to have been rewritten by the R / P head 6, and the erasing in this case poses no problem in magnetic recording.

Except that the azimuth angles of the gaps 13 and 14 formed in the respective R / P and FE heads 10 and 11 differ from the azimuth angles α of the gaps 8 and 9 of the A head 1. The B head 2 has the same configuration as the A head 1 described above. (12) represents non-magnetic material.

The A and B heads 1 and 2 scan the magnetic tape 3 along the magnetic track in the following manner.

The R / P head 5 of the A head ₁ scans the magnetic tape 3 according to the A track A ₁ , while the FE head 6 scans according to the B track B ₁ . After a predetermined time has elapsed (for example, after half rotation of the rotary member 4), the R / P head 10 of the B head 2 indicated by the imaginary line in FIG. By scanning according to the same B track (B ₁ ) previously scanned, the FE head 11 is scanned according to the A track (A ₂ ). After further rotating the rotary member 4, the R / P head 5 of the head A ₁ scans along the A track A ₂ , and the FE head 6 tracks the B track B ₂ . Inject along.

In the same manner as described above, the A and B heads 1 and 2 are connected to the continuous recording tracks A ₁ , A ₂ . … And B ₁ , B ₂ . … According to a more detailed description, the head A 1 erases the B track with the FE head 6 while the R / P head 5 also uses the continuous tracks A ₁ , A ₂ . … Written to, and, B head 2 has a continuous track as R / P head 10, while erasing the track A to the FE head (11) B _1, B ₂ ... … To record.

Magnetic heads, on the other hand, are typically made by bonding a plurality of magnetic plates to one another to cut synthetic flakes to a constant length. With such a head configuration, the junction points of the magnetic heads are partially used as gaps. The A and B heads (1) and (2) according to the present invention can be easily produced by the above method. On the other hand, in the magnetic head according to the present invention, the gaps 9 and 14 formed in the FE heads 6 and 11 of the A and B heads 1 and 2, respectively, are R / P heads 5. And parallel to the gaps 8 and 13 formed in (10), respectively. By the above method, since the A head 1 can be manufactured by joining the R / P head 5 and the FE head 6 with, for example, a nonmagnetic material 7, the gaps 8 and 9 can be formed. High degree of parallelism can be secured.

The case where the predetermined video tape editing is performed using the A and B heads 1 and 2 according to the present invention is described. That is, FIG. 4 is a schematic diagram of a magnetic tape, and FIG. 5 shows a circuit configuration for obtaining a gate signal necessary for inserting a frame of a video signal, and FIGS. 6A to 6K show a time difference art for this circuit.

As an example of video tape editing, a case of inserting three frames of a new video signal (P in Fig. 4) in a recorded magnetic tape will be described. Several gate signals are necessary for editing the three frames (P in FIG. 4) in order to control the operation of the FE heads 6 and 11 and the R / P heads 5 and 10. FIG.

In order to obtain these gate signals, an RF switching fund a (FIG. 6a), which is made in a synchronous separator circuit or the like in accordance with a predetermined video signal a, has a pulse width FLD substituted for one feed, is shown in FIG. It is supplied to the first input terminal 20 shown in FIG. The pulse signal a is connected to the pulse edge detection circuit 21 to remove the rising edge of the switching pulse signal a. The detection circuit 21 produces a pulse signal b (Fig. 6B) corresponding to the rising edge of the signal a.

On the other hand, the command signal c (Fig. 6C) having a predetermined width corresponding to the three video frames is supplied to the second input terminal 22. This command signal c is connected to the data terminal of the D-flop flop 23, and the pulse signal b from the detection circuit 21 is supplied to the trigger terminal. The D-flip flop 23 serves to synchronize the rising and falling edges of the command signal with the pulse signal b. As a result, the D-flip flop 23 supplies the synchronization command signal d (Fig. 6d) to its Q output. The Q and Q outputs of the D-flip flop 23 are supplied to the trigger terminals of the monostable mulberry vibrator circuits 24 and 25. These multivibrator circuits 24 and 25 are provided so that one video feed delays the positive going edges of the Q and Q outputs from the flip-flop 23 for about half a period. Q outputs (FIGS. 6E and 6F) are derived from these multivibrator circuits 24 and 25, and are supplied to flip-flop 26 and OR gate 27, respectively. That is, the monostable multivibrator circuit 28 having the time constant of the corresponding one video feed section through the OR gate 27 is formed of the funnels e (FIG. 6E) e and (f) (FIG. 6F). Triggered on both positive going edges. Therefore, flip-flop 28 generates a delay pulse h (Fig. 6h) at its Q output. The positive go edge of the delay pulse h triggers another monostable multivibrator circuit 30 having a time constant of one corresponding video feed section. The Q output of the multivibrator circuit 30 supplies the delay pulse j (Fig. 6j) to the flip-flop 31. The delay pulse h also triggers a flip-flop 29. As a result, the flip-flop 26 supplies the first control pulse g (figure 6g) to the output terminal 32 and the flip-flop 29 supplies the second control pulse i to the output terminal 33. (FIG. 6I) is supplied, and the flip-flop 31 supplies the third control pulse k (FIG. 6K) to the output terminal 34. FIG.

Since the B head 2 is in contact with the video tape 3 when the RF switch pulse is high, the first control pulse g is applied to control the erase current to the FE head 6. The second control pulse i is applied to control the erase current to the FE head 11 and to control the write current to the R / P head 12. In contrast, a third control pulse k is applied to control the write current to the R / P head 5.

As described above, according to the present invention, the A and B heads 1 and 2 fixed on the toe member 4 are respectively the R / P head 5 or 10 and the FE head 6. Or a gap 8 or 13 formed in the RP head 5 or 10 and a gap 9 or 14 formed in the FE head 6 or 11 since the unitary structure including the 11 is formed. High accuracy in the direction of) can be ensured. In addition, the time required for mounting the A and B heads 1 and 2 can be shortened, and these heads can be individually and independently and accurately mounted on the rotary member (or rotary drum). Has much superiority over the prior art.

Also, unlike the conventional head assembly provided on the rotary drum in a position where the video head and the erasing head are spaced apart by a predetermined distance, the R / P heads of the A and B heads 1 and 2 are respectively. Since (5) and (10) are integral with the coupling FE heads 6 and 11, respectively, the impact generated when the video head and the erasing head start or end contact with the magnetic tape in the prior art. The error can be eliminated.

In addition, according to the present invention, the FE heads 6 and 11 are the video tracks A ₁ , A ₂ ,. … And B ₁ , B ₂ . … The erasing operation of the FE heads 6 and 11 with respect to the coupling R / P heads 5 and 10 is disposed so as to precede the write operation of the coupling R / P heads 5 and 10. Therefore, the FE head 6 of the A head 1, these tracks B ₁ , B ₂ . … The video tracks B ₁ , B ₂ ... … Is traced.

In addition, according to the present invention, the gaps 9 and 14 of the FE heads 6 and 11 are formed by the R / P head 5 and the track scanning direction (for example, the arrow F in FIG. 4). Since it is provided in the preceding position with respect to each of gaps 8 and 13 of (10), the video tracks A ₁ , A ₂ ,. … And B ₁ , B ₂ . … The data recorded by the R / P heads 5 and 10 in the FE head (for example, in the directions of video tracks A ₁ , A ₂ ,... And B ₁ , B ₂ ... There is no possibility of being partially erased by the leaking inside of 6) and (11).

The above embodiment relates to, but is not limited to, a magnetic recording and reproducing apparatus using a combined magnetic head having a predetermined azimuth angle α. For example, as shown in FIG. 8, the effective gaps 9a and 8a of each of the FE and R / P heads 6a and 5a do not have an azimuth angle, and have a predetermined distance G. An example using the spaced magnetic head 1a is shown. Such a head can be used for a magnetic recording and reproducing apparatus, and a predetermined guard band is provided between adjacent recording tracks.

Claims (1)

Magnetic recording in which recording tracks adjacent to each other on a magnetic tape are sequentially formed so that the recording tracks adjacent to each other are different azimuth angles by rotating drums on which the first and second recording heads having first and second recording head gap azimuth angles are placed. A reproducing apparatus, wherein the first and second scavenging heads are disposed proximate to the first and second recording heads relative to the first and second recording heads in the rotational direction of the rotating drum. At the same time, the azimuth angles of the first recording head and the first erasing head are made to be substantially the same, and the azimuth angles of the second recording head and the second erasing head are made to be substantially the same. The track recorded by the head at the second azimuth angle is erased, then recorded by the second recording head, and recorded by the second erase head at the first azimuth angle. Erase, and then the magnetic recording and reproducing apparatus, characterized in that the recording to the recording head of the first a.

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