JPS61253979A - Rotary head type magnetic picture recording and reproducing device - Google Patents

Abstract

PURPOSE:To perform direct recording without any intervention of an image delay circuit and further eliminate the distortion of an image surface during reproduction by providing a couple of rotary recording heads which have a mutual step, a couple of rotary playback heads which have no step, and a device which drives a tape intermittently. CONSTITUTION:An L head 13 for recording and an R head 14 for recording are fitted in a pair to the rotary part of a rotary cylinder 8 at an interval of 180 deg. while having the mutual step l and trace different surfaces through the rotation of the cylinder. An L head 15 for reproduction and an R head 16 for reproduction have no step and trace the same surface. A tape speed has three periods, i.e. acceleration period, constant-speed period, and deceleration period and a recording current is flowed to the two L and R rotary heads in the constant-speed period to record one frame. Tape feed in which recording is not performed in the acceleration and deceleration period is absorbed by the step of the heads to obtain the same head track as that of continuous reproduction, and its playback output waveform has a constant horizontal synchronizing signal period, so that no distortion appears in an image surface.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rotating head type magnetic recording/reproducing device, and in particular to an intermittently magnetic tape (hereinafter abbreviated as tape).
It is used in devices that drive frame-by-frame recording over long periods of time.

2. Description of the Related Art In recent years, long-time video tape recorders that perform frame-by-frame recording are called time-lag video and have been widely used for monitoring and security purposes in financial institutions and other institutions.

In time-lag video, the tape drive system during recording is intermittent drive, so unlike the recording pattern of the generally widely used VH3 system, the interval between horizontal synchronization signals when playing back an intermittent drive recording tape is 1 field. It becomes discontinuous every time. As a result, distortion occurs on the television 957 screen. Conventionally, in order to prevent this distortion, a video delay circuit 3 and a switching circuit 7 are used as shown in FIG.
The video signal was delayed so that the horizontal equal amount signals during playback were at equal intervals, and recorded by a rotating radar 2 attached to a rotating cylinder 1.

Problems to be Solved by the Invention However, in the conventional example, the video delay circuit 3
is the modulation circuit 4. Glass delay line6. However, due to the band limitation of the glass delay line 5 and deterioration of characteristics due to spurious damage prevention, problems arose in that the input video signal could not be faithfully recorded.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, it is an object of the present invention to provide a rotary head type magnetic recording and reproducing apparatus which directly records data without using a video delay circuit and which does not cause screen distortion during reproduction.

Means for Solving the Problems In order to solve the above-mentioned problems, the rotary head type magnetic recording and reproducing apparatus of the present invention includes a pair of recording rotary heads attached to a rotary cylinder and having a step between them; It is equipped with a pair of rotary heads for reproduction without a tape, a device that drives the tape intermittently, and a control device that controls them.

Effect of the Invention With the above-described configuration, the present invention does not delay the video signal, and even if it is added directly to the rotary head, the horizontal synchronization signal intervals are equal due to the effect of the stepped recording rotary head, and screen distortion during playback is avoided. This makes it possible to eliminate the occurrence of

Embodiments Hereinafter, rotary head type magnetic recording and reproducing apparatuses according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention. In FIG. 1, reference numeral 8 denotes a rotary cylinder, and recording and reproduction on the tape 11 is performed by a head attached to this rotary cylinder 8 (this will be described later). The tape 11 is driven between a capstan 9 and a pinch roller 10, and a control circuit 12 controls the tape 11.

FIG. 2 is a detailed view of the rotary cylinder 8 shown in FIG. 1. The recording L head 13 and the recording R head 14 are a pair, have a step between each other, and have a 180-degree angle on the rotating part of the rotary cylinder 8.
They are installed at a distance.

Trace different surfaces by rotating the cylinder.

This is the key point of the invention. The level difference between the reproduction L head 15 and the reproduction R head 16 is zero.

Trace the same surface.

FIG. 3 is a diagram showing the level difference between the recording L head 13 and the recording R head 14. In FIG. 3, e is a step, and the value of e is a value that is uniquely determined given the tape speed during intermittent driving.

The intermittent drive recording operation and playback operation of the rotary head type magnetic recording and reproducing apparatus according to the present embodiment configured as described above will be explained with reference to FIGS. 4 to 8. First, the operation when there is no level difference will be explained, and the reason why screen distortion occurs during playback will be explained. Next, the operation when there is a level difference will be explained and its effects will be described.

FIG. 4 shows the tape speed and recording timing in intermittent drive recording. The tape speed is divided into three periods: an acceleration period, a constant speed period, and a deceleration period. During this constant speed period, recording current is passed through the 12 rotating heads to record one frame.

FIG. 6 shows a tape pattern recorded using a pair of rotary heads with no steps. The areas with hatching are patterns recorded with the L head, and the areas without hatching are patterns recorded with the R head. 17
represents a horizontal synchronizing signal, and for the sake of simplicity, the number of horizontal scanning lines in one frame is assumed to be five. During the acceleration period and deceleration period in FIG. 4, the tape runs in the direction of arrow F without recording, resulting in the guard band 18 in FIG. 6. The trajectory of the L head when this tape pattern is continuously fed and reproduced at a uniform speed is shown by a broken line in the figure. Since the trajectory of the R head is controlled by the control circuit 12 in FIG. 1, it matches the recorded trajectory. In addition.

G in FIG. 6 indicates the scanning (movement) direction of the head.

FIG. 6 shows a signal output waveform when the tape pattern of FIG. 6 is continuously fed and reproduced at a uniform speed, and M, B, C, and D match those of FIG. 5. In FIG. 6, it can be seen that the spacing is narrower in part B. Discontinuity in this interval appears as screen distortion.

FIG. 7 shows a tape pattern when recording is performed intermittently using the stepped head shown in FIG. The step e of the head absorbs the tape feeding without recording during the acceleration period and deceleration period in FIG. 4.

! The pattern is the same as the head trajectory of continuous playback as shown in Fig. 7, and the playback output waveform has a constant horizontal synchronizing signal interval as shown in Fig. 8, and distortion of one screen does not occur.As described above, according to this embodiment, The tape pattern with the step difference can be the same as that of continuous tape drive, and screen distortion during playback can be prevented.

Effects of the Invention As described above, according to the present invention, in intermittent drive recording, it is possible to obtain an excellent effect that no screen distortion occurs during playback even if direct recording is performed without using a video delay circuit.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a perspective view of a rotating cylinder in the embodiment, Fig. 3 is a positional relationship diagram of the recording head in the embodiment, and Fig. 4 is a tape speed characteristic. Figures 6 and 7 are tape pattern diagrams,
8 and 8 are output waveform diagrams of reproduced signals, and FIG. 9 is a block diagram of a conventional example. 8...Rotating cylinder, 9...Capstan, 1o...Pinch roller, 11...
・Tape, 12... Control circuit, 13...
・L head for recording, 14...R head for recording,
15...L head for reproduction, 16...R head for reproduction, 17...Horizontal synchronization signal. 18...Gart band. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure f@454 A cylinder 6 diagram

Claims (1)

[Claims] A pair of recording rotary heads with a step difference attached to a rotary cylinder, a pair of reproducing rotary heads without a step difference, a device for intermittently driving a magnetic tape, and a control device for controlling them. A rotary head type magnetic recording and reproducing device characterized by comprising: