JPS61296505A - Magnetic tape and helical scan magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain retrieval at high speed by recording a signal relating to the recording position of information so as to be arranged on a line having a nearly equal angle to an angle of a locus traced by a rotary magnetic head on each track when a tape is run at a speed faster than that at a normal recording and reproducing state. CONSTITUTION:The m-th program is recorded on a track 7 of a sector X and the (m+1)-th program is recorded on a track 7 of a sector Y respectively, no program is recorded on a track 7 of a sector Z between the sectors to form non-information part (inter-music). In the sector Z, the location of the start of a track 8 is arranged on line segment with angles theta1 and theta2 from the running direction. The angles theta1 and theta2 are angles of locus traced by rotary magnetic heads A, B respectively when a magnetic tape 1 is fed fast and the magnetic head 1 rewound. Thus, the rotary magnetic head traces the part recorded with the position signal continuously when the magnetic tape 1 is rewound or fast-fed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic tapes and helical scan magnetic recording and reproducing apparatuses typified by video tapes and video tape recorders.

[Conventional technology]

It is desirable to be able to quickly search for a predetermined recording position on a video tape or the like in which information is recorded over a long period of time. -21861). To briefly explain the contents, for example, in a so-called 8m video tape recorder, as shown in FIG.
It is wound approximately 221 degrees around a rotating drum 2 having two rotating magnetic heads A and B spaced apart by 80 degrees.

As a result, as shown in FIG. 5, on the magnetic tape 1, in addition to the cue track 5 and audio track 6 formed by a fixed head (not shown), tracks 7 and 8 that are inclined with respect to the running direction are formed. Ru. Track 7 is approximately 1
This part corresponds to a winding angle of 85 degrees, of which 18
Normally, one field of video signal is recorded in the 0 degree portion. Track 8 corresponds to the remaining winding angle of 36 degrees and is the part where digital information is recorded.1 For example, in the case of the NTSC system, there is a clock part with a maximum of 5°oO6 where clock signals are recorded, and a clock part where the clock signal is recorded, and a clock part where the PCM audio signal etc. A data area of 26.32° where a predetermined data signal is recorded, a margin area of 2°06° for after-recording, and a 2°62° area where a part of the video signal of the immediately previous field is recorded in an overlapping manner. It consists of a video overlap section of °. The above-mentioned proposal records a signal regarding the recording position of information in this data section. That is, in the track where the m-th program is recorded, a signal related to the beginning position of the m-th program and a signal related to the beginning positions of the (m-1)th programs are recorded, and the signals between the programs are recorded. In the intervening tracks with no information, the beginning positions of all programs recorded on the magnetic tape are recorded. Therefore, by running the magnetic tape for several seconds at a normal playback speed and reading the data signal, the program position before the current position can be determined and the position can be searched. If the program is after the current position, the magnetic tape is fast-forwarded to the first non-information area, and then the normal playback mode is resumed. If the data area signal is read, the desired program position can be found and searched. can do.

[Problem that the invention seeks to solve]

However, in such a conventional method, the running speed of the magnetic tape could not be made very high because the signals recorded in the data section were read. In other words, if the magnetic tape is rewound or fast-forwarded at n times the normal recording/playback speed and the position signal recorded in the data section of track 8 is read, then n tracks are read in track 7 at 180 degrees. Therefore, the number of lines crossing the data section of track 8 is 26.32n/180.

According to experiments, signals recorded in the data section can be read at speeds that are at most 9 times the speed of normal recording or playback, and faster than that (e.g. approximately 30
It was impossible to read the data signal during rewind or fast forward (double speed). For example, if you want to search at 9 times the normal speed, you will have to set the speed at which the magnetic tape runs, not only during normal recording and playback, rewinding or fast forwarding, but also when searching. , the control of the drive system, calculations for determining the tape position, etc. are complicated, and the device is expensive.

[Means for solving problems]

FIG. 1 shows the case where the present invention is applied to an 8I video tape recorder. FIG. 2 is a block diagram of a recording system. In the figure, 11 and 12 are switches.

The contact points are switched by a head switching pulse (H'5WP) that switches between the rotating magnetic heads A and B. A timing circuit 13 generates and outputs a signal at a predetermined timing in synchronization with the head switching pulse. 14 is a pulse generating circuit whose output controls the switch 15. 16.
Reference numeral 17 denotes an amplifier circuit, which amplifies and outputs a video signal and a position information signal, respectively. The video signal is supplied to the rotary magnetic head A or B via switch 11 or 12, respectively, and the position information signal is supplied to switch 15 and 11 or switch 15 and 12.
It is designed to be supplied to the rotating magnetic head A or B through the respective rotary magnetic heads.

[Effect]

The operation will be explained with reference to FIGS. 2 and 3. The timing circuit 13 gradually increases its width (the interval between time t□ and 1..1 and t4, etc. in FIG. 2) in synchronization with the headlash switching pulse (FIG. 2(a)). , generates a pulse that decreases when it reaches a predetermined value, and increases again when it reaches a predetermined value. This pulse is supplied to the pulse generating circuit 14, and is output as a pulse whose polarity is alternately inverted between positive and negative (FIG. 2(b)).

The switch 15 is set to the solid line side when this)<Rus b is positive.
When it is negative, it is switched to the dashed-dotted line side, and when it is zero, it is switched to the dashed line side. On the other hand, the switches 11 and 12 are switched to the solid line side when the headlash switching pulse a is negative, and to the broken line side when it is positive.

Therefore, for example, at time t1, head switching pulse a and pulse b are both positive, and switch 11.12
Since the switch 15 is switched to the broken line side and the switch 15 is switched to the solid line side, the position information signal is input to the rotating magnetic head A. At time t2, the head switching pulse a becomes negative and the pulse b becomes zero, so the switches 11 and 12 are switched to the solid line side, and the switch 15 is switched to the broken line side.

Therefore, a video signal is supplied to the rotating magnetic head A. At time t3, the pulse b becomes negative, the switch 15 is switched to the one-dot chain line side, and the position information signal is input to the rotating magnetic head B. At time t4, the head switching pulse a becomes positive and the pulse b becomes zero, so switches 11, 12, and 15 are all switched to the dashed line side, and a video signal is recorded on the rotating magnetic head B. At time t, the situation is similar to that at time t. As a result, the tracks recorded by the rotating magnetic head A (Fig. 2 (C)
)) and the track recorded by the rotating magnetic head B (
In FIG. 2(d)), the length of the portion 7 where the video signal is recorded does not change, but the length of the portion 8 where the data signal (position information signal) is recorded (recording start position) is changed in each track. Change.

FIG. 3 schematically shows a track pattern on a magnetic tape on which position signals are recorded in this manner. The mth program is recorded on track 7 of area X, the m+1th program is recorded on track 7 of area Y, and no program is recorded on track 7 of area Z between them. , there is no information (between songs). In the region Z, the position of the beginning of the track 8 is aligned on a straight line forming an angle 02 with the angle θ□. The angle θ1 is the angle of the trajectory traced by the rotary magnetic heads A and B when the magnetic tape 1 is fast forwarded, and the angle θ2 is the angle of the locus traced by the rotating magnetic heads A and B when the magnetic tape 1 is rewound. The angle θ□ and the angle 02 are θ1=tan-' [πRsinθG/(7CRCO
8θ. -n V/f) )O2=tan-1CπR
51nO.

/ (πRcosOo+nV/f): 1. 0 here. is the angle of the trace locus of the rotating magnetic heads A and B during still playback, R is the radius of rotation of the rotating magnetic heads A and B, and n is the running speed of the magnetic tape during normal recording and playback during fast forwarding or rewinding. The magnification for V, f is the frequency of the vertical synchronization signal. If the rewinding or fast forwarding speed of an 8++wu video tape recorder is 30 times the speed V during normal recording and playback, then in a system with 525 lines and 60 fields, such as the NTSC system, for example, 0□=5°30' 5
0.9"θ2=4°23'4.1". On the other hand, in a system with 625 lines and 50 fields, such as the PAL system, θ□=6°2'
21.5"θ2=466'1.8". These angles can be set by appropriately adjusting the timing of the timing circuit 13.

In this way, in region 2, the beginning of the track 8 is sequentially shifted to provide a substantially sawtooth-like non-signal section 21, and the angle of the sawtooth wave is changed to the trace locus of the rotating magnetic head when rewinding by 1 or fast forwarding by 1. When the magnetic tape 1 is rewound or fast-forwarded, the rotating magnetic head can continuously trace the area where position signals are recorded, and the area just before that is a no-signal area. This reduces noise and makes it easier to read position signals. For example, a signal with a predetermined frequency may be used as the position signal, and its presence or absence (logical 0 or 1) can be detected. Further, in order to control the trace locus of the rotating magnetic head, the tracking error signal may be sampled and held.

In the above description, the position signal is obtained for both rewinding and fast forwarding, but it may also be possible for only one of them. In that case, the amount of the original signal to be deleted in the track 8 will be reduced. Furthermore, in a device that changes the rotational speed of a rotating magnetic head during high-speed running, the angle of the sawtooth wave may be made to match the trace angle in that case.

〔effect〕

As described above, in the present invention, the signals related to the recording position of information are aligned in each track on a line with an angle approximately equal to the angle of the locus traced by the rotating magnetic head when running at a faster speed than during normal recording and reproduction. Since the information is recorded in this manner, it becomes possible for the rotating magnetic head to continuously trace the portion where the signal related to the recording position is recorded, making it easy to read the signal. Therefore, high speed search is possible.

[Brief explanation of drawings]

Figure 1 is a block diagram of the recording system when the present invention is applied to an 8-video tape recorder, Figure 2 is an explanatory diagram explaining the relationship between the waveform and track pattern, and Figure 3 is the track on the magnetic tape. FIG. 4 is a schematic plan view of a conventional rotary magnetic head, and FIG. 5 is a schematic plan view of a track pattern on the magnetic tape. 1... Magnetic tape 2... Rotating drum 7.8...
- Tracks 11, 12, 15...Switch 13...Timing circuit 14...Pulse generation circuit 16.17...Amplification circuit 21...No signal section or higher

Claims (2)

[Claims] (1) A magnetic tape in which information is recorded on a plurality of tracks inclined with respect to the running direction, and a signal regarding the recording position of the information is run on each track at a faster speed than during normal recording and reproduction. What is claimed is: 1. A magnetic tape in which information is recorded so as to be aligned on a line having an angle substantially equal to the angle of a locus traced by a rotating magnetic head. (2) In a helical scan magnetic recording and reproducing apparatus that runs a magnetic tape at a first speed and records information on tracks inclined with respect to the running direction of the magnetic tape using a rotating magnetic head, the magnetic tape is moved at a first speed. The magnetic tape is caused to run at a speed of 1, and a signal regarding the recording position of the information is recorded on a plurality of the tracks, and the recording position of the signal in each track is such that the magnetic tape is moved at a second speed faster than the first speed. A helical scan magnetic recording/reproducing device characterized in that recording is performed so as to be aligned on a line having an angle substantially equal to the angle of a locus traced by the rotary magnetic head when the rotating magnetic head is running.