JPH0754564B2 - Erasing device in recording or reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an erasing device in a recording or reproducing device for magnetically recording or reproducing a video signal or the like, and relates to a recording track for recording a recording signal on a recording medium. The problem is the characteristics of an erase signal that can be erased wider than the width and efficiently.

BACKGROUND ART For example, roughly categorized as a conventional erasing device in a recording or reproducing device for magnetically recording or reproducing a video signal and the like using a magnetic sheet as a recording medium, (1) whole recording by a bulk erasing device Track erasing (2) Erase head separate from recording or reproducing head and erasing by AC or DC erasing signal (3) Recording or reproducing head also used as erasing head, AC or DC The erasure signal is used for erasing. The present invention is mainly applied to the device (3) in which the recording or reproducing head is also used as the erasing head, but it is also applicable to the device (2) in which the erasing head is separately provided.

OBJECT OF THE INVENTION It is an object of the present invention to provide an erasing device capable of erasing efficiently for each recording track and wider than the recording track.

Further, the present invention provides an erasing device capable of efficiently erasing in a high magnetic susceptibility region of a magnetic material forming a head by erasing with a low frequency erasing signal outside the frequency band of a recording or reproducing signal. The purpose is to provide.

A further object of the present invention is to provide an erasing device which can perform erasing wider than a recording track by erasing by utilizing low frequency leakage magnetic flux.

Structure of the Present Invention The present invention relates to a recording or reproducing apparatus for recording a video signal including horizontal and vertical synchronization signals on a recording medium and reproducing the video signal recorded on the recording medium. Then, for example, the recording or reproducing head 3) of FIG. 1; and a low frequency vibration having a constant frequency outside the frequency band of the recording signal recorded on the recording medium or the reproduction signal reproduced from the recording medium. An erasing signal, wherein the oscillation of the erasing signal is maintained at a substantially constant amplitude for a first period in synchronization with a vertical synchronizing signal included in the video signal, and then, for a second period following the first period. An erase signal source for generating an erase signal having a constant amplitude gradually attenuated (also the erase signal source of FIG. 1 for generating the erase signal shown in FIG. 2).
11) and; means for supplying an erase signal generated from the erase signal source to the magnetic head to generate a magnetic field according to the erase signal (also connecting the erase signal source 11 in FIG. 1 to the recording or reproducing coil 4). Circuit) and; and an erasing device in a recording or reproducing device.

In the above, the citation of specific examples described later does not limit the scope of the present invention, and the present invention can be appropriately modified within the scope of the claims.

Hereinafter, the configuration of an erasing device embodying the present invention, its operation, and its modification will be described in detail with reference to the drawings.

Configuration of an erasing device embodying the present invention (FIGS. 1 and 2) FIG. 1 shows an erasing device embodying the present invention in which a recording medium is a magnetic sheet and recording or reproducing head recording or It shows a specific example of supplying an erase signal to the reproducing coil. In the figure, 1 is a magnetic sheet, 2 is its rotation motor, 3 is a recording or reproducing head composed of a magnetic head,
Reference numeral 4 is a recording or reproducing coil wound around the recording or reproducing head. A video signal input terminal 5 is connected to an image pickup device such as an image pickup tube or a solid-state image pickup element. A video signal processing circuit 6 converts an input video signal into a signal suitable for recording, and the converted signal is a recording amplifier 7 and a switch.
It is supplied to the recording or reproducing coil 4 of the recording or reproducing head 3 via the a terminal of S1 and recorded on the magnetic sheet 1 as is known. At the time of reproduction, the signal recorded on the magnetic sheet 1 is picked up by the recording or reproduction coil 4, and the switch S1
The signal is supplied to the reproduction signal processing circuit 9 through the b terminal and the reproduction amplifier 8 and converted into a signal suitable for visual display and displayed on the display device 10.

Reference numeral 11 represents an erase signal source which is a main feature of the present invention.
The erasing signal generated by this signal source is low-frequency vibration outside the frequency band of the recording or reproducing signal, and as shown in FIG. 2, a continuous vibration period (T1) and a damping vibration period (T1) that allow a constant amplitude. T2) and included. To generate low-frequency oscillation with such characteristics, insert a damping element into the tuning circuit of the low-frequency oscillator after the period T1 has elapsed, and either attenuate according to the time constant of the tuning circuit in this case, or The vibration may be amplitude-modulated by a waveform corresponding to the envelope of the waveform shown in FIG. Here, a specific numerical example of the erase signal shown in FIG. 2 will be described. These numerical values fluctuate depending on the materials of the magnetic sheet 1 and the recording or reproducing head 3 and the frequency band of the recording or reproducing signal.
The frequency E of the erasing signal is 0.5 to 5 KHz, the continuous oscillation period T1 is 0.1 to 1 second, and the damping oscillation period T2 is 1 to 2 when the video signal of 1 field is recorded for each concentric track. Seconds may be allowed, and the amplitude of the continuous oscillation may be 30-40 mA when the period T1 is 0.2-0.4 seconds.

The erasing signal generated by the erasing signal source 11 is amplified by the recording amplifier 7 via the d terminal of the switch S2 connected to the c terminal at the time of recording, and the recording or reproducing coil 4 of the recording or reproducing head 3 is amplified.
To erase the signal recorded on the magnetic sheet 1. If the frequency of the erase signal is approximately 3 KHz or higher, it can be amplified by the recording amplifier 7. However, if the frequency is lower than that, a dedicated erase signal amplifier can be provided.

Operation of the erasing device embodying the present invention (FIGS. 1 to 3) In order to erase a desired track on the magnetic sheet 1 by the erasing device embodying the present invention, recording is performed by, for example, a known feeding mechanism. Alternatively, the reproducing head 3 is moved to the desired track position and the switches S1 and S2 are switched to supply the erasing signal to the recording or reproducing coil 4. As described above, the erasing signal includes the continuous vibration having a constant amplitude during the period T1 and the damping vibration during the period T2. Therefore, the magnetization in the magnetic sheet 1 is saturated during the continuous vibration period T1. , The original recording signal of the recording track is overwritten and erased, and then the distortion is removed during the damping oscillation period T2.

Since the frequency E of the erasing signal is a low frequency outside the band of the recording or reproducing signal as described above, the recording or reproducing head 3 constituted by the magnetic head operates in the region where the magnetic permeability is high, so that the magnetic flux density is large. Therefore, the erasing efficiency is improved and the erasing can be performed in a short time. Even if the erasing signal component remains, it is a size that can be ignored as a beat component that may occur during re-recording. Further, as shown in FIG. 3, the low frequency vibration has a large amount of leakage magnetic flux φl which is leaked to the outside at the headgear part 3a, so that even if there is some track deviation at the position of the recording or reproducing head 3, the original recording The signal can be erased wide enough.

Modification of the erasing device embodying the present invention In the device shown in FIG. 1, the erasing signal is sent to the recording or reproducing coil 4 for erasing, but another erasing coil is wound around the recording or reproducing head 3 and An erase signal may be sent. Further, an erasing head may be provided in addition to the recording or reproducing head 3 and an erasing signal may be sent to a coil wound around the erasing head.

Further, as shown in FIG. 4, if the continuous oscillation period T1 and the decay oscillation period T2 of the vertical synchronizing signal a and the erase signal b are synchronized,
Each of these periods and the period of the sum thereof can be arbitrarily changed with the cycle of the vertical synchronizing signal as a unit, and reproduction-erasure-recording and sequence are performed by the pulse generated based on the vertical synchronizing signal as shown in FIG. It can be operated.

EFFECTS OF THE INVENTION The present invention is based on the above-described configuration and operation, and in a recording or reproducing apparatus for recording a video signal including horizontal and vertical synchronization signals on a recording medium and reproducing the video signal recorded on the recording medium, An erasing signal of low-frequency vibration, which is outside a frequency band of a recording signal recorded on the recording medium or a reproducing signal reproduced from the recording medium and has a constant frequency, wherein the vibration of the erasing signal is the video signal. To be erased by an erase signal in which the constant amplitude is gradually attenuated in a second period subsequent to the first period in synchronization with a vertical synchronization signal included in the first period. Therefore, for each recording track of the recording medium, it is possible to operate in the high magnetic susceptibility region of the magnetic head for efficient erasing, and due to the low frequency leakage magnetic flux The first period during which the oscillation of the erase signal can be continuously erased with a constant amplitude, and the second period during which the constant amplitude is gradually attenuated following the first period and the sum thereof. The period can be arbitrarily changed with the cycle of the vertical synchronizing signal as a unit.

[Brief description of drawings]

FIG. 1 is a block diagram of an erasing device embodying the present invention,
FIG. 2 is a waveform diagram of an erase signal in the device of FIG. 1, and FIG.
Similarly, FIG. 4 is an explanatory diagram of the leakage magnetic flux, and FIG. 4 is an explanatory diagram of the operation of a modified example of the erasing device of the present invention. In the figure, 1 is a magnetic sheet as a recording medium, 3 is a recording or reproducing head, 4 is a recording or reproducing coil, and 11 is an erasing signal source.

Claims (2)

[Claims] 1. A recording or reproducing apparatus for recording a video signal including horizontal and vertical synchronization signals on a recording medium and reproducing the video signal recorded on the recording medium, comprising: a magnetic head; and a recording medium recorded on the recording medium. A vertical sync signal which is an erasing signal of a low frequency vibration which is outside the frequency band of the recording signal reproduced from the recording medium or which is reproduced from the recording medium and which has a constant frequency, wherein the vibration of the erasing signal is included in the video signal. An erasing signal source for generating an erasing signal by gradually attenuating the constant amplitude for a second period following the first period in synchronism with An erasing device in a recording or reproducing apparatus, comprising: means for supplying an erasing signal generated by the erasing signal source to generate a magnetic field according to the erasing signal. 2. The magnetic head is a recording or reproducing head, and means for generating a magnetic field according to the erasing signal in the recording or reproducing head connects the erasing signal source to a recording or reproducing coil of the recording or reproducing head. An erasing device in a recording or reproducing device according to claim 1 which is means.