JPS61253984A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To draw the same head scanning track as that in normal reproduction by equalizing the tilt angle of a tape guide to the track angle during normal reproduction previously. CONSTITUTION:A head scanning track I when a magnetic tape 1 does not run has the same scanning track start position with a head scanning track II-2 in normal reproduction, but shifts in scanning track end position by about one track pitch to the adjacent track right before it. In this case, the tilt angle of the tape guide 8 is so set that a rotary head which draws a scanning track as shown by an alternate long and two short dashes line when the magnetic tape 1 does not run draws a scanning track as shown by a solid line II-2, i.e. the same scanning track as that in standardized normal reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording apparatus, and more particularly to a magnetic recording apparatus having a function of stopping the running of a magnetic tape during recording and recording information signals using a rotary head.

Conventional Technology A time-lapse VTR has been known as a type of helical scan type magnetic recording/reproducing device (VTR).This device has different speed modes for recording, and the magnetic tape is continuously run at a low speed during recording. A VTR that can record for a long time, for example, up to 240 hours on a 2-hour standard time tape, by performing intermittent step-running and frame-by-frame recording (field sampling) of the video signal.
It is. Such time-lapse VTRs are used for purposes such as reproducing recorded edge video signals on magnetic tape and analyzing their contents in detail, or transmitting photographs of specific playback screens to preserve records for a long time. It is widely applied to monitoring purposes for crime prevention and security, work analysis at corporate sites, logistics records, recording the progress of broadcasting programs at television broadcasting stations, and recording and analyzing long-term experimental observation data at schools and research institutes. ing.

Problems to be Solved by the Invention In such a time-lapse VTR, it is possible to perform so-called still recording in which the running of the magnetic tape is stopped and a video signal is recorded by a rotating head. In order to analyze the desired recorded content in detail, normal playback may be performed to quickly and accurately search for the recorded content. However, in still recording and normal playback, although the rotating speed of the rotary head is the same, the running speed of the magnetic tape is different, so the scanning trajectory of the head is different from each other.
Therefore, during normal playback, the rotary head cannot accurately scan still-recorded tracks, resulting in problems such as noise bars appearing in the playback video signal and a drop in S/N.

Therefore, an object of the present invention is to provide a magnetic recording device that solves the above problems by setting the lead angle in advance so that the same head scanning locus as during normal reproduction is drawn during still recording. do.

Means for Solving the Problems The magnetic recording device of the present invention is such that the angle between the scanning locus of the rotary head on the magnetic tape whose running is stopped and the longitudinal direction of the magnetic tape is equal to the angle formed during normal playback according to the standard. The inclination angle of the tape guide is selected in advance so that it is equal to the track angle of .

In the working helical scan type VTR, when the magnetic tape 1 stops running as shown in FIG. 3, the rotary head draws a scanning locus with the track center line having a track angle θ0 as shown by the two-dot chain line . On the other hand, during normal playback, the first and second rotating heads mounted opposite each other on the rotating surface of the rotating body alternately change the track center line from ll-1 to I[[
-1→ll-2→m-2→... solid line ll-
1 to I[-3, broken line ■-1 to I[[-3] Draw a scanning locus of video track angle θ (θ>θ0) as shown in the figure. Here, the solid lines I-1 to If-3 are the scanning loci of the track center line during normal playback by the first rotary head, and the broken line ■-1
~ll-3 indicates a scanning locus of the track center line during normal playback by the second rotary head. Therefore, compared to the head scanning trajectory IF-2 during normal playback, the head scanning trajectory when the magnetic tape 1 stops running has the same scanning trajectory starting position, but only about one track pitch at the scanning trajectory ending position. , it will shift to the immediately adjacent track side.

Due to the selection of the inclination angle (lead angle) of the tape guide, when the magnetic tape 1 stops running, the rotary head conventionally draws a scanning trajectory as shown by the double-dashed line in FIG. In other words, the same scanning trajectory as that during normal playback according to the standard is drawn. Embodiments of the present invention will be described below with reference to the drawings.

Embodiment FIG. 1 shows a perspective view of a drum, etc., illustrating an embodiment of the apparatus of the present invention. In the figure, rotating heads 3 and 4 are mounted and fixed facing each other on the lower rotating surface of an upper rotating drum 2, which is an example of a rotating body. It is configured such that its height position can be displaced by the electro-mechanical conversion element (not shown in FIG. 1) described above. The upper rotating drum 2 is arranged so that its bottom surface faces the upper surface of the lower fixed drum 5 by a short distance, and the rotating shaft of a motor (not shown) passes through the center of the lower fixed drum to connect the upper rotating drum to the upper rotating drum. The upper rotating drum 2 is fixed at the center of the motor, and only the upper rotating drum 2 is rotated counterclockwise as the motor rotates. The magnetic tape 6 is guided by a guide ball 7, a tape guide 8 formed on the lower fixed drum 5, and a guide ball 9, so that the magnetic tape 6 is oriented diagonally and at 180° on the circumferential side of the upper rotating drum 2 and the lower fixed drum 5. Splice-wound over a strong angle range,
During normal playback, normal recording, etc., it is held by a capstan and pinch rollers (not shown) and is made to run in the direction of the arrow.

The above is a well-known structure for VTRs, but the invention is based on the inclination angle of the tape guide 8 formed on the lower fixed drum 5 (
That is, the angle θ between the scanning locus of the rotary head when the magnetic tape stops running and the longitudinal direction of the magnetic tape 1a3 shown in FIG. ) is selected and formed to be equal to the standard track angle θ during normal playback. - As an example, the above track angle θ is 5.96942°
The conventional angle θ0 was 5.935388°, but it is set to 5.96942@. Therefore, according to this embodiment, when the magnetic tape 6 stops running, it is possible to record and form tracks having the same inclination angle θ as during normal playback of existing VTRs. However, on the other hand, when performing normal playback of the edge information signal recorded on the magnetic tape 6 according to this embodiment, it is clear that the same head scanning locus as that during normal playback of existing VTRs is not drawn. As shown in FIG. 2(A) or (B), the rotary heads 3 and 4 are displaced in the track width direction independently of each other by electromechanical transducers 10 and 11, and accurately move on the marked edge track. Tracking control possible. On the other hand, when performing normal playback on an existing VTR in order to search the recorded contents of a recording track group recorded still according to this embodiment,
A high-quality reproduced video signal can be obtained without generating noise bars or deteriorating the S/N ratio.

Here, the above-mentioned electro-mechanical transducers 10 and 11 are publicly known, and for example, two piezoelectric element plates are attached that expand and contract according to the input voltage value, and one of which expands and the other compresses in response to the same input voltage. The rotary head 3 or 4 has a structure in which one end in the direction of expansion and contraction is fixed and the other end is closed and a - rotating head 3 or 4 is attached depending on the input voltage. The height position is displaced in the direction perpendicular to the rotating surface (track width direction).

Electro-mechanical conversion element 10.11. As shown in FIGS. 2A and 2B, the rotating heads 3 and 4 rotate 180 degrees on the rotating surfaces of the upper rotating drums 2a and 2b, which are examples of rotating bodies.
They are installed facing each other at an angular interval of The azimuth angles of the rotary heads 3 and 4 are selected to be opposite to each other, as shown by 3a and 4a. By the counterclockwise rotation of the upper rotary drum 2a, the rotary heads 3 and 4 alternately slide on the magnetic tape 6 for each field, and the third and third rotary heads slide on the magnetic tape 6, which has stopped running during still recording. As described above with reference to the figures, information signals such as video signals are recorded forming video tracks having the same inclination angle θ as during normal playback (however, during standardized normal playback in existing VTRs).

When the formation of one recording track is completed, the magnetic tape 6
is moved in steps for one track pitch and then stopped, and still recording similar to the above is performed again.

In addition to the rotating heads 3 and 4, two rotating heads 12 and 13 are mounted on the rotating surface of the upper rotating drum 2b shown in FIG. 2(B), facing each other. There is. The rotating heads 3 and 4 each have an electro-mechanical conversion element 1
0 and 11, their height positions can be varied independently of each other, but the rotary heads 12 and 13 are fixedly mounted on the rotary drum 2b, respectively, and their height positions are always constant. Further, the azimuth angles of the rotary heads 12.13 are different from each other, as shown by 12a and 13a, and the rotary heads 3, 12.4, and 13 are the same, respectively.

During still recording and still playback, in the case of the two-head configuration shown in FIG. 2(A), a fixed voltage is applied to the electro-mechanical transducers 10 and 11 to make them inactive, as shown in FIG. 2(B). In the case of a four-head configuration, rotating heads 12 and 13 are used. On the other hand, in the case of normal playback and variable speed playback,
In both of the head configurations shown in FIGS. 2(A) and 2(B), the rotating heads 3 and 4 are used, and the tracking deviation of the rotating heads 3 and 4 is Noise-barless reproduction is possible by generating and applying a control voltage according to known means. However, in the case of normal recording, a control voltage that changes at a constant cycle is applied to the electro-mechanical transducers io and 1i to form a normal recording track with a predetermined inclination angle θ.

Note that the track length during normal recording is 2.2 as shown in FIG. If the track length during still recording is 20, l/
The scanning error P, denoted by Ilo, is - for example, 9
6.82911. If fl o is 97.382 mm, the value is 0.99432, which means that, strictly speaking, the drum circumference, that is, the drum diameter, is approximately 0.57% of the existing VTR.
Although it is necessary to make the drum smaller than the conventional one, in practice there is almost no problem even if the drum diameter is not changed.

Note that the present invention is not limited to the above-described embodiment, and the information signal to be recorded may be other than a video signal, and the rotating body may be the upper rotating drums 2, 2a.

It is not limited to a cylindrical shape such as 2b, but may be a flat rectangular bar-shaped plate with rotating heads attached to both ends.

Effects of the Invention As described above, according to the present invention, during still recording, it is possible to draw the same head scanning locus as during normal playback, and information signals can be recorded on the same recording track as for normal recording. When performing normal playback to search the recorded contents of a track group, it is possible to obtain a high-quality playback signal without generating noise bars or deteriorating the S/N ratio, making the search more reliable. In addition, during still recording, a still recording track with the same inclination angle as during normal playback can be formed by simply tilting the tape guide without using an electro-mechanical conversion element, so it has features such as high reliability. be.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a drum etc. for explaining one embodiment of the device of the present invention, FIGS. 2(A) and (B) are plan views showing each side of the head arrangement of the device of the present invention, and FIG. 3 FIG. 2 is a diagram illustrating head scanning trajectories during normal playback and still recording. 1.6... Magnetic tape, 2.2a, 2b... Upper rotating drum, 3, 4.12.13... Rotating drum, 5.
・Lower fixed drum, 8...Tape guide, 10゜1
1...Electro-mechanical conversion element.

Claims (1)

[Claims] A magnetic recording device that records information signals on a magnetic tape whose running is stopped by a rotating head attached to the rotating surface of a rotating body around which the magnetic tape is guided and wound by a tape guide, The tape guide is adjusted in advance so that the angle formed between the scanning locus of the rotary head on the magnetic tape whose running has been stopped and the longitudinal direction of the magnetic tape is equal to the track angle during normal playback according to the standard. The recording track of the information signal is formed on the magnetic tape whose running is stopped by selecting an inclination angle, by drawing the same scanning locus of the rotary head as during normal playback according to the standard. magnetic recording device.