JPS6394408A - Information signal recording/reproducing/eliminating method and its compound magnetic head - Google Patents

Abstract

PURPOSE:To record, reproduce and eliminate satisfactorily an information signal by recording the information signal with a first head in which a scanning width is narrower than the width of a guard band, reproducing it with a second head width than the width of the guard bank and causing an eliminating current to flow to both heads and eliminating the information signal. CONSTITUTION:On tracks T1 and T2 for the picture signal of a magnetic disk 200, gap parts 111 and 112 of a thin film head 110 for the picture signal are positioned. In this condition, the disk 200 is rotated, a current is caused to flow at the coil of respective gap parts 111 and 112 of the head 110 and the picture signal is recorded. At this time, a guard band G is formed between both tracks T1 and T2. In order to reproduce the picture signal, the same position condition as recording is obtained and the picture signal is obtained from tracks T1 and T2 by the gap parts 111 and 112. At the time of the recording, execution is performed with the head in which the scanning width is narrower than the width of the band G, and at the time of the reproducing, execution is performed with the head wider than the width of the band G. Further, at the time of eliminating, the eliminating is executed without fail by causing an eliminating current to flow at both heads.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for recording, reproducing, and erasing signals on a rotating magnetic disk and its composite magnetic head, and relates to a method for recording, reproducing, and erasing signals on a rotating magnetic disk. It is designed to be able to record, reproduce, and erase information signals.

<Prior Art> When recording information on a magnetic disk, such as a floppy disk, the floppy disk is rotated and information is recorded on annular tracks.

Also, generally, a guard band is provided between two adjacent tracks. The guard band is provided to absorb tracking deviations due to expansion and contraction of the floppy disk due to changes in temperature and humidity and positioning errors due to accuracy of the head tracking mechanism.

There are various types of magnetic recording devices that use floppy disks as recording media, but still images are recorded by so-called electronic still cameras, which convert the image of a subject obtained through a lens into an electrical signal and record it on a floppy disk. The device is known. A floppy disk for this purpose is called a video floppy. For reproduction, there is known a device that rotates a floppy disk and reproduces an image signal recorded on a track as a still image on a display device such as a television receiver.

In these devices, one field of the image signal is recorded in one round of the track. This method of reproducing one still image using image signals for one field is called field recording and reproducing. In addition, a method of recording one field of the same frame on two tracks each, constructing one frame using the image signals from the two tracks, and playing back one still image is called frame recording and playback. . According to the standards for electronic still cameras, the floppy disk is rotated at 3600 rpm, and tracks 60 μm wide are formed concentrically at a pitch of 100 μm.

The width of the guard band is nominally 40 μm, and the allowable width of the track radius due to expansion and contraction of the floppy disk is ±14 μm.
It is said that

On the other hand, when displaying still images on a telepicillin receiver, etc.
In response to the strong demand for simultaneously outputting audio, music, etc. that correspond to image signals, a method for recording this information on a guard band was proposed in Japanese Patent Laid-Open Nos. 61-129701 and 6
No. 1-153803, respectively. In other words, the conventional track is used as the main track to record image signals, and the guard band between the main tracks is used to temporally compress and record information signals such as audio. Record the signal as desired. The information signal recorded in a temporally compressed manner is expanded to its original state during playback. The magnetic head for recording image signals on the main track and the magnetic head for recording information signals on the guard band may be provided independently, or they may be integrated as proposed in JP-A-61-129701. Sometimes it is done.

Here, a circuit and its operation for recording and reproducing image signals and audio signals using a composite magnetic head in which a pair of image signal heads sandwich an information signal head and its operation will be explained with reference to FIG. explain.

In FIG. 3, a color signal of a still image obtained from the photographing system 10 is sent to an FM modulator 11A.

11B and then added, the signal passes through the gate 12 and is recorded on the magnetic disk 30 by the image signal heads 21 and 22 of the three-track composite magnetic head 20.

On the other hand, the audio signal obtained from the microphone 40 is amplified by the amplifier 41, and then is converted to 1/6 by the time axis compression port 1542.
The compressed audio signal is compressed to 0 seconds, and is recorded on the audio signal track of the magnetic disk 30 by the audio signal head 23 in the composite magnetic head 20 via the FM modulator 43. When reproducing an audio signal, the audio signal recorded on the magnetic disk 30 is also detected by the information signal head 23, amplified by the amplifier 44, and then FM demodulated by the FM [modulator 45]. The decompression circuit 46 restores the original audio signal. This restored audio signal is outputted as an audio signal via an amplifier 47. The image signal recorded on the magnetic disk 30 is similarly detected by the image signal heads 21 and 22 and displayed as a still image on a display device such as a television receiver by a well-known reproduction system (not shown).

<Problems to be Solved by the Invention> By the way, in the conventional technology, information signals such as audio are recorded over the entire width of the guard band. Therefore, if the tracking deviates even slightly, the following problems occur.

In other words, if the tracking deviates when recording the information signal, it will disturb the image signal already written in the image signal track, and if the tracking deviates when the information signal is reproduced, the level of the reproduced information signal will drop and the image signal will be distorted. If the S/N ratio decreases due to contamination, and tracking shifts during erasing, part of the image signal track may be erased.

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, it is an object of the present invention to provide a method for recording, reproducing, and erasing information signals that can record and reproduce information signals in good condition and erase them accurately and reliably, and a composite magnetic head thereof. .

Means for Solving the Problems> The information signal recording/reproducing/erasing method of the present invention that achieves the above object records/reproduces the information signal in a guard band formed between adjacent tracks on which image signals are recorded. In the reproducing/erasing method, an information signal is recorded by a first head having an azimuth angle with respect to the image signal head forming the track and having a scanning width narrower than the width of the guard band; Reproducing the information signal by a second head having the same azimuth angle as the head and having a scanning width greater than or equal to the scanning width of the first head, and positioning the first and second heads on the same guard band. The information signal is erased by causing an erase current to flow through both heads.

Further, the composite magnetic head of the present invention includes an image signal head that forms an image signal track by attaching a guard band to a rotating magnetic disk, and a guard band that is shifted in the track width direction with respect to the image signal head. a first head that is located at an azimuth angle with respect to the image signal head and records the information signal with a scanning width narrower than the width of the guard band;
By being shifted in the circumferential direction of the track relative to the first head, the second head is positioned on the same guard band as the first head, has the same azimuth angle as the first head, and has a width greater than the scanning width of the first head. It is characterized in that it is integrally equipped with a second head that reproduces an information signal with a scanning width that is equal to the width of the scanning width.

Function> The first head, whose scanning width is narrower than the width of the guard band, records information signals on the guard band, and the second head, whose scanning width is greater than or equal to the scanning width of the first head, records the information signal on the guard band. Regenerate information signals from the band. Further, during erasing, the information signal is erased by passing an erasing current through the first and second heads.

Example of implementation Embodiments of the present invention will be described in detail below based on the drawings.

FIG. 1 is a configuration diagram of a composite magnetic head according to an embodiment of the present invention, viewed from its sliding surface side.

This composite magnetic head 100 has a structure in which a thin film head 110 for image signals, a thin film head 120 for audio signal reproduction, and a thin film head 130 for recording audio signals are bonded and integrated. The magnetic disk moves in the direction of arrow A relative to the head 100. The thin film rad 110 has a gap width T1. It has a pair of gap portions 111 and 112 in which l is 60 μm, respectively, and a gap T corresponding to the guard band width (40 μm) is provided between both gap portions 111 and 112.

On the other hand, the thin film head 120 has a gap part 121 for audio signal reproduction with a gap width of T, .
It has an azimuth angle of angle θ with respect to 2. This gap portion 121 is located on the guard band between the image signal tracks formed by the gap portions 111 and 112, and has a scanning width of 5 (=T1.l') for scanning the magnetic disk by the gap portion 121. (g) θ) is equal to the guard band width T0. Also, the thin film head 130
has a gap part 131 for recording an audio signal, which is a gap part T', and this gap part 131 has an azimuth angle of θ with respect to the gap parts 111 and 112. This gap portion 131 is similar to the gap portion 11
The scanning width 52 (=T,' θ) that is located on the guard band between the image signal tracks formed by It is narrower than T0. Note that since the gap portion 131 is a head for recording audio, its gap length (length along the direction in which magnetic flux passes through the gap) is longer than the gap length of the gap portion 121 for reproducing audio.

A method for recording and reproducing an image signal and a method for recording, reproducing, and erasing an audio signal using the composite magnetic head 100 shown in FIG. 1 will be sequentially explained below.

Image signal recording/reproduction method: To record an image signal, a magnetic disk 2 shown in Fig. 2 is used.
00 image signal track Tl.

Gap portions 111 and 112 of the thin film head 110 for image signals are positioned above T2. In this state, while rotating the magnetic disk 200, image signals are recorded on the tracks T, , T, by passing an image current 41 through the coils (not shown) in the respective gap portions 111 and 112 of the thin film radar 110. be done. At this time, a guard punt G is formed between both tracks T, , T. To play the image signal,
Gap parts 111 and 112 in the same position as recorded.
By truck T.

An image signal is obtained from T2.

Method of recording audio signals: In the case of so-called after-recording, in which lines and sound effects are recorded later while viewing the reproduced image, the image is recorded from the image signal tracks T, T2 using the gap portions 111 and 112 of the thin film head 110. While reproducing the signal, the composite magnetic helad 100 is tracked so that the envelope value of the caterpillar signal of the image signal becomes the peak value. When such tracking is performed, the gap portion 131 of the thin-film head 130 for recording audio signals is aligned with the magnetic disk 2.
It is located in the center of guard band G of 00. Therefore, by passing an audio signal current through a coil (not shown) in the gap portion 131, a narrower audio signal track T3 is formed on the gear G, and the audio signal is recorded.

In such audio recording, the scanning width S2 of the gap portion 131, ie, the width of the track T3, is narrower than the width T of the guard band G. Therefore, even if the tracking accuracy is rough,
The gap portion 131 does not overlap the image signal tracks Tl, T, and there is no possibility of disturbing the image signals of the image signal tracks T, T2, allowing accurate audio recording.

Method of reproducing an audio signal: To reproduce an audio signal, the gap portion 121 of the R4 film head 120 for audio signal reproduction is positioned on the audio signal track T3 of the magnetic disk 200, and the audio signal is reproduced. . Tracking at this time is performed by controlling the composite magnetic head 100 so that the envelope value of the reproduced signal of the video (No. 8) becomes the maximum, or the envelope value of the reproduced signal of the audio signal becomes the maximum. Execute.

In such audio reproduction, the gap portion 121 is connected to the image signal track T1. Even if T2 is applied, crosstalk due to the video signal hardly occurs due to the effect of azimuth loss. Therefore, even if the tracking is rough, good audio reproduction is possible.

Methods for erasing audio signals: There are two methods for erasing audio signals:

In the first erasing method, the thin film head 12 for audio signal reproduction is
0 gap section 121 and RIll for audio signal recording.
! The gap portion 131 of the head 130 is positioned on the audio signal track L. In this state, the track T3 is scanned while an erase current is applied to the coil in the gap portion 121 and the coil in the gap portion 131. As a result, the track T,
The audio signal recorded in the .

In the above erasing, the erasing efficiency by the gap portion 131 is higher than the erasing efficiency by the gap portion 121. This is because the gap length of the gap portion 131 is longer than that of the gap portion 121. Therefore, even if there is an unerased part that cannot be erased in the gap part 131 due to a slight deviation in tracking, this unerased part will be left in the gap part 121.
It is largely erased by In this case, the unerased portions are not completely erased, but since their area is small, this is hardly a problem in reality. For this reason, with the first erasing method, even if the tracking is rough, erasing can be performed reliably. Note that even if the gap part 121 covers the image signal track T or T during erasing, the erasing efficiency by the gap part 121 is low and there is an azimuth angle, so that the data is recorded on the image signal track T or T. Attenuation of the image signal is extremely small.

In the second erasing method, a thin film head 130 for recording audio signals is used.
Erase using chisel. That is, an erasing current is applied to the coil in the gap portion 131 to scan the audio signal track T3.

Although this second erasing method requires accurate tracking to perform complete erasing, it has the advantage that erasing current only needs to flow through one R4 film head 130.

In the above embodiment, the scanning width S of the gap portion 121 is $i! of the guard band G. 7. However, the scanning width S may be made larger than the guard band width T0. In other words, S may be ≧Tc. Further, the information signal may be an image signal in addition to an audio signal. Further, the composite magnetic head is not limited to a thin-film head, but may be a bulk type head.

<Effects of the Invention> As specifically explained above in conjunction with the embodiments, according to the present invention, information signals can be recorded and reproduced satisfactorily, and the information signals can be reliably erased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a composite magnetic head according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a recording pattern on a magnetic disk, and FIG. 3 is a block diagram showing a recording/reproducing circuit. In the drawing, 100 is a composite magnetic head, 110, 120, 130 are F9 film heads, 111, 1
12. 121. 131 is a gap portion. Patent application Agent: Fuji Photo Film Co., Ltd.

Claims (3)

[Claims] (1) In a method for recording, reproducing, and erasing information signals on a guard band formed between adjacent tracks on which image signals are recorded, the guard band has an azimuth angle with respect to the image signal head forming the tracks, and The information signal is recorded by a first head whose scanning width is narrower than the width of the guard band, and which has the same azimuth angle as the first head and whose scanning width is greater than or equal to the scanning width of the first head. Information signal recording characterized in that the information signal is reproduced by a second head, the first and second heads are positioned on the same guard band, and the information signal is erased by flowing an erasing current to both heads.・
How to play/delete. (2) The information signal recording/reproducing/erasing method according to claim (1), wherein the gap length of the first head is larger than the gap length of the second head. (3) An image signal head that attaches a guard band to a rotating magnetic disk to form an image signal track; The first head has an azimuth angle with respect to the guard band head and records the information signal with a scanning width narrower than the width of the guard band.
The head is positioned on the same guard band as the first head by being shifted in the circumferential direction of the track with respect to the first head, and has the same azimuth angle as the first head, and A composite magnetic head, characterized in that it is integrally equipped with a second head that reproduces an information signal with a scanning width that is greater than the scanning width.