JPH0963004A - Erasing device of electronic still camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simply and inexpensively manufactured erasing device for a magnetic device capable of obtaining a sufficient erasing rate without DC magnetization remaining. SOLUTION: After an erasing switch is turned ON, by instruction from a system controller 8 and at a timing synchronized with the rotational cycle of a magnetic disk 1, for each fixed period, DC voltage and AC voltage signals each having fixed polarity are supplied to a magnetic head 2 for a specified period. Thus, erasing is performed by a sufficient erasing rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an erasing device for a magnetic recording type electronic still camera, and more particularly to an erasing device for erasing a magnetic recording portion on which a video signal is recorded.

[0002]

2. Description of the Related Art As a conventional erasing device for a magnetic recording type electronic still camera, an erasing device for applying a direct current to a recording / reproducing magnetic head for erasing and an erasing device for applying an alternating current to the magnetic head for erasing have been proposed. ing.

An erasing method has also been proposed in which these are combined and then AC erasing is further performed after DC erasing (JP-A-62-287402).

[0004]

As shown in FIG. 3, in the DC erasing method, the positive and negative polarities are alternately changed in the magnetic head, and the DC current is made to flow gradually so that the DC current level gradually decreases. Erasing is performed, and the magnetic flux density is changed in response to changes in the current, and some DC magnetization settles down.Therefore, when re-recording as it is, distortion of the reproduced signal occurs due to the effect of the remaining DC magnetization. There was a problem that it would end up.

Further, in the AC erasing method, erasing can be performed by supplying a large current to the magnetic head in order to obtain a sufficient erasing rate. However, in reality, the recording amplifier and the magnetic head are saturated and a large current is consumed. Can not be flushed.

Further, in the DC / AC combined erasing device in which both are combined, there is a problem that the erasing device is complicated and expensive.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve these problems and to provide an erasing device capable of erasing with a simple control system. In a magnetic recording type electronic still camera, a magnetic head is first used. An erasing device for an electronic still camera, characterized in that a magnetic recording portion of a magnetic disk is erased by applying a predetermined DC voltage for a certain period to an AC signal of a certain frequency and then flowing an AC signal with a certain amplitude for a certain period. To do.

According to the above construction, the current to be passed through the magnetic head has only to be applied with a predetermined DC voltage for a certain period, a complicated circuit for inverting polarity such as DC erasing is not required, and the level needs to be gradually decreased. Nor.

Further, the amplitude of the AC signal after applying the DC voltage to the magnetic head does not need to be as large as the amplitude when erasing only by AC erasing. As for the amplitude required for erasing, a sufficient erasing rate can be obtained by applying an amplitude that allows the use of a recording amplifier used for recording.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of an embodiment of the present invention, and FIG. 2 shows an illustration of an erasing method of the embodiment. In FIG. 1, 1 is a magnetic disk, 2 is a magnetic head, 3 is a recording amplifier, 4 is a modulator, 5 is a video signal processing circuit, 6 is a DC voltage generator, 7 is an AC signal generator, 8 is a system controller, Reference numeral 9 is an erasing switch.

Next, the operation of the erasing method of this embodiment will be described with reference to FIG. Select the track of the magnetic disk you want to erase and press the erase switch 9. Then, the magnetic disk 1 rotates at a constant speed. When the erasing switch 9 is turned on, the DC voltage generator 6 and the AC signal generator 7 apply DC to the magnetic head 2 for a certain period at a timing synchronized with the rotation cycle of the magnetic disk 1 according to an instruction from the system controller 8. Voltage and alternating current (AC) signals are passed in sequence as shown in FIG.

Here, the DC voltage may be applied for at least one rotation time of the disk, and the AC signal may be erased for at least one rotation time of the disk.

Further, there may be a period in which the DC voltage and the AC signal are simultaneously flowing, and if only the AC signal is flowing during the last one rotation time of the actual erasing time, and if they are erased in this order, the DC magnetization is eliminated. Everything can be erased.

Further, in this system, one track can be erased by rotating the disk twice. At this time, the disc may be rotated before the erase switch is pressed. Further, the amplitude of the DC voltage can be supplied from the power supply voltage.

Further, the AC signal having a frequency outside the band of the recorded information signal may be always set, and it is economical to use the clock used in the system.

The frequency of the AC signal may be a rectangular wave AC signal having a high harmonic level as long as the fundamental wave is out of the band. Here, even if the relative speed between the magnetic disk and the magnetic head changes depending on the rotation speed or the track of the magnetic disk, it is sufficient that the frequency is always outside the frequency band of the recorded information signal.

[0017]

As described above, according to the structure and method of the present invention, the DC voltage and the AC signal are rotated by the erasing device having a simple and inexpensive structure such as diverting the power supply voltage and the system clock. The magnetic disk can be erased without leaving DC magnetization by obtaining a sufficient erasing rate by simply passing it to the magnetic head in accordance with the timing.

That is, a complicated circuit for changing the polarity of DC erasing is unnecessary, and if a system clock is diverted, a circuit for newly generating an AC signal for erasing is also unnecessary. The amplitude of erasing can reduce the current consumption as compared with the case of flowing alone, which also saves the battery and the battery.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an erasing method according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional DC erasing method.

[Explanation of symbols]

 1 magnetic disk 2 magnetic head 3 recording amplifier 4 modulator 5 video signal processing circuit 6 DC voltage generator 7 AC signal generator 8 system controller 9 erase switch

Claims (1)

[Claims] 1. In a magnetic recording type electronic still camera, a magnetic recording is performed on a magnetic disk by first applying a predetermined DC voltage to a magnetic head for a certain period and then applying an AC signal of a certain frequency with a certain amplitude for a certain period. An erasing device for an electronic still camera, which erases parts.