JPS59110008A - Erasing device of recording or reproducing device - Google Patents

Abstract

PURPOSE:To operate a magnetic head in its high permeability area for every recording track of a recording medium and to perform efficient erasure by using an erasing signal which contains sustained oscillation and oscillation that follows it and attenuates gradually for the erasure. CONSTITUTION:When a desired track on a magnetic sheet 1 is erased, a recording or reproducing head 3 is moved to the desired track and switches S1 and S2 are changed over to supply said erasing signal to a recording or reproducing coil 4. The erasing signal contains the sustained oscillation which allows a constant amplitude in a period T1 and the attenuating oscillation in a period T2. The magnetic sheet 1 is saturated with magnetism in this sustained oscillation period T1 to erase the original recording signal on the recording track by superposition recording and then distortion is removed in the attenuating oscillation period T2. Magnetic flux phil leaking out of a head gap part 3a is much, so the original recording signal is erased to sufficiently wide width even when the recording or reproducing head 3 shifts in position from the track slightly.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical field to which the present invention pertains The present invention relates to an erasing device in a recording or reproducing apparatus for magnetically recording or reproducing video signals, etc. The purpose of the present invention is to address the characteristics of an erase signal that can be erased more efficiently and wider than its width.

BACKGROUND ART Conventionally proposed erasing devices for recording or reproducing devices that use a magnetic sheet as a recording medium and magnetically record or reproduce video signals, etc. can be roughly divided into: (1) Bulk erasing device for all recording. Track erasing (2) Using an erasing head separate from the recording or playback head and erasing using an AC or DC erase signal. (6) Track erasing using an AC or DC erase signal that also uses the recording or playback head as the erase head. It is classified as something that is erased depending on the signal. The present invention is mainly applied to a device (6) in which the recording or reproducing head also serves as an erasing head, but it can also be applied to a device (2) in which a separate erasing head is provided.

Purpose of the Invention An object of the present invention is to provide an erasing device that can efficiently erase each recording track and over a wider area than the recording track. It is an object of the present invention to provide an erasing device that can efficiently erase in a high permeability region of a magnetic material constituting a head by performing erasing using a low frequency erasing signal outside the frequency band.

A further object of the present invention is to provide an erasing device that is capable of erasing data over a wider area than the recording track by using low-frequency leakage magnetic flux.

Structure of the Invention The present invention provides a magnetic head (in a specific example described later, for example, the recording or reproducing head 6 in FIG. 1); an erase signal source (the erase signal source 11 in FIG. 1 which also generates the erase signal shown in FIG. 2) that generates an erase signal including a subsequent gradually attenuated vibration; An erasing device in a recording or reproducing apparatus is characterized in that it comprises means for generating the erasing signal (a circuit for connecting the erasing signal source 11 of FIG. 1 to the recording or reproducing coil 4);

In the above, the citation of the specific examples described later does not limit the scope of the present invention in any way, and the invention can be modified as appropriate within the scope of the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an erasing device embodying the present invention will be described in detail in the order of its structure, operation, and modifications thereof.

Structure of an erasing device embodying the present invention (Figs. 1 and 2) Figure 1 shows an erasing device embodying the invention in which the recording medium is a magnetic sheet and the recording or reproducing head has a recording medium. Alternatively, a specific example of supplying an erase signal to a reproducing coil is shown. In the figure, 1 is a magnetic sheet, 2 is a rotating motor thereof, and 6 is a recording or reproducing head composed of a magnetic head.
4 is a recording or reproducing coil wound around the recording or reproducing head. Reference numeral 5 denotes a video signal input terminal, and 06, which is connected to an imaging device such as an image pickup tube or solid-state imaging confectionery, is a video signal processing circuit that converts the input video signal into a signal suitable for recording. The signal is supplied via the recording amplifier 7 and the a terminal of the switch S1 to the recording or reproducing coil 4 of the recording or reproducing head 3, where it is recorded by IK (magnetic sheathing) in a known manner. During reproduction, the signal recorded on the magnetic sheet 1 is picked up by the recording or reproducing coil 4, and the switch f
The signal is supplied to the reproduction signal processing circuit 9 via the b terminal of 81 and the reproduction amplifier 8, where it is converted into a signal suitable for visible display and displayed on the display device 10.

11 is an erasure signal source which is a main feature of the present invention, and the erasure signal generated by this signal source is a low frequency perturbation outside the frequency band of the recorded or reproduced signal, and as shown in FIG. It includes a sustained vibration period (T1) that allows constant amplitude and a damped vibration period (T2).

To generate low-frequency oscillations with such characteristics, a damping element is inserted into the tuned circuit of the low-frequency oscillator at the elapsed time of Jυ1ilTl, and the damping element is attenuated according to the time constant of the tuned circuit in this case, or the low-frequency oscillations are may be amplitude-modulated using a waveform corresponding to the envelope of the waveform shown in FIG. Here, the erasing signal shown in FIG. 2 will be explained using a specific numerical example. These values vary depending on the material of the magnetic sheet 1 and the recording or reproducing head filter, as well as the frequency band of recording or reproducing 4: '+43', but the number of revolutions of the magnetic sheet 1 is 3.60V, and the concentric circles [-When one field of video signal is recorded for each rack, the frequency fE of the erase signal is 0.5 to 5 KH2, and the sustained vibration period T1.
is 0.1 to 1 second, the damped vibration period T2 is 1 to 2 seconds, and the amplitude of the sustained vibration is such that the period T1 is 0.2 seconds.
~0.4 seconds, it is allowed to be 30-4071 LA.

The signal is amplified by the recording amplifier 7 and supplied to the recording/reproducing coil 4 of the recording/reproducing head B, thereby erasing the signal recorded on the magnetic sheet 1. The frequency of the erase signal is approximately 3KH2
If the frequency is higher than that, it can be amplified by the recording amplifier 7, but if the frequency is lower than that, it is possible to provide a dedicated erasure signal amplifier.

Operation of the erasing device embodying the present invention (Figs. 1 to 6) In order to erase a desired track on the magnetic sheet 1 using the erasing device embodying the present invention, for example, a known feeding mechanism is used to record the data. Alternatively, move the playback head to the desired track position mentioned above and press 2-bit S1. S2 is switched to supply the above-mentioned erasure signal to the recording or reproducing coil 4. As described above, the erasure signal includes a sustained vibration that allows a constant amplitude during the period T1 and a damped vibration during the period T2, so that the magnetization in the TIK magnetic sheet 1 is saturated during this sustained vibration period, The original recording signal on the recording track is overwritten and erased, and then the distortion is removed during the damped vibration period T2.

Since the frequency fε of the erase signal is a low frequency outside the band of the recording or reproduction signal as described above, the recording or reproduction head 3 is composed of a magnetic head.Since the recording or reproduction head 3 operates in a region where the magnetic permeability is low, the magnetic flux density is low. It becomes thinner, the erasing efficiency improves, and it can be erased in a short time. Furthermore, even if the erased signal component remains, its size is negligible as a beat component with a probability of i<L occurring during re-recording. Furthermore, as shown in FIG. 3, low-frequency vibrations have a large amount of magnetic flux φl leaking to the outside at the head gap portion 3a, so even if there is a slight track deviation in the position of the recording or reproducing head 6,
The original recording signal can be erased over a sufficiently wide range. ○ Modified example of the erasing device embodying the present invention In the device shown in FIG. A separate erasing coil is wound around the reproducing head 3, and an erasing signal is passed through it (c1. may also be used).

Furthermore, an erasing head may be provided in addition to the recording or reproducing head 6, and an erasing signal may be passed through a coil wound around the erasing head.

Furthermore, as shown in FIG. 4, if the vertical synchronization signal a and the continuous vibration period T1 and the attenuation capturing period T2 of the erasure signal are synchronized, each of these periods and the period of their sum will become the period of the vertical synchronization signal. can be changed arbitrarily as a unit, and C
As shown in FIG. 2, reproduction-erase-record sequence operations can be performed using pulses generated based on the vertical synchronization signal.

Effects of the Invention The present invention is based on the above-described structure and operation, and erases data using a recording/erasing signal.
Erasing can be performed efficiently, and erasing can be performed over a wider area than the recording track width due to low-frequency leakage flux.

[Brief explanation of drawings]

FIG. 1 shows an erasing device embodying the present invention. 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 recording medium 111 (air sheet, 4I'f is a recording or reproducing head, 4I'f is a recording or reproducing fill, and 11 is an erasure signal source □ CA, i and .

Claims (2)

[Claims] (1) a magnetic head; an erasing signal source that generates an erasing signal that is a low-frequency vibration outside the frequency band of the recording or reproduction signal and includes a sustained vibration followed by a gradually attenuating vibration; An erasing device in a recording or reproducing device, comprising: means for generating a magnetic field by the erasing signal button. (2) The magnetic head is a recording or reproducing head, and the means for generating a magnetic field by the erasing signal in the recording or reproducing head is an erasing device in this recording or reproducing head-down reproducing apparatus.