JPS5938923A - Magnetic head - Google Patents

Abstract

PURPOSE:To obtain a magnetic head which is suited to a miniaturized device, by making the head gaps of two pairs of magnetic matter cores to have a different length to use the core having a larger head gap length as a recording core and the having a shorter head gap length as a reproducing core respectively and therefore reducing the bias applying current in a high-speed dubbing record mode. CONSTITUTION:For instance, four cores 5, 5', 5'' and 5''' are provided in a shielding case 1 for a stereo type cassette tape magnetic head. For head gaps 6, 6', 6'' and 6''', the adjacent cores 5 and 5' are set in a pair and used for reproduction with the length of gaps 6 and 6' set at about 1.2mu respectively. While the length of gaps 6'' and 6''' is set at about 4-5mu for a pair of cores 5'' and 5''', and these cores are used for recording. Thus a magnetic head which is capable of sound recording with a low level of power consumption is obtained for a cassette tape deck having a dubbing function to record the reproduced signal of a recorded master tape to an unrecorded tape at a high speed for copy. This miniaturizes easily a device using the magnetic head.

Description

[Detailed Description of the Invention] The invention in the industrial field of application is mainly to play back a recorded master tape at a high speed higher than a constant speed, and at the same time record this playback signal on an unrecorded slave tape at a high speed. The present invention relates to a magnetic head mounted on a cassette tape recorder with a radio receiver or a cassette tape deck, which has a dubbing function for duplicating a master tape.

Conventional Structure and Problems A conventional tape recorder with a dubbing function has two tape running sections, one of which is used for recording and playback, and the other is used only for playback. Normal constant-speed recording is performed using the above-mentioned recording/playback section, and reproduction is performed using either the recording/playback section or the playback-only section. Furthermore, when dubbing is performed, a master tape such as a U music tape is played back in a playback-only section, and the playback signal is recorded on an unrecorded slave tape in a recording/playback section.

One of the unique features of such a tape recorder with a dubbing function is that it can reproduce data at a constant speed using two running sections, and it is common to have a recording/playback section and a section dedicated to playback. For this reason, a recording/reproducing head is used as the magnetic head used in the recording/reproducing section.

Figure 1 shows a stereo type recording/playback head.

In this case, the core 2.2' around which the coil is wound is provided with gear knobs 3, 3' at the portion in contact with the magnetic tape. During recording, a signal current and bias current are passed through the coil,
Recording is performed on the magnetic tape by the signal magnetic field leaking through the gap η1. However, during reproduction, the signal magnetic flux recorded on the magnetic tape flows through the core from the gap portion, generating an induced voltage in the coil proportional to the time change of the signal magnetic flux. As is clear from the above explanation, the recording/playback head uses the same core during recording and playback.
Coils and gaps are used.

Now, when performing high-speed dubbing, it is necessary to shift the reproduced signal frequency to a high frequency range in proportion to the tape running speed during dubbing, and to record the reproduced signal shifted to this high frequency range on the slave tape. Furthermore, when recording, the highest signal frequency
An alternating current bias with a frequency more than double the frequency must be superimposed on the recording signal and applied to the recording/playback head. However, the impedance of the core wrapped around the magnetic head is proportional to the frequency. Therefore, in order to generate a magnetic field sufficient for bias during high-speed dubbing, a high voltage oscillation circuit that generates a high voltage is required, which causes the problem that the bias oscillation circuit becomes large.

In addition, the recording/playback head is designed with emphasis on the characteristics of a playback head in terms of gear-related dimensions, shielding, etc., and coil impedance, etc., are designed with emphasis on characteristics as a recording head. In particular, the relationship between the gap length and the high frequency reproduction frequency is generally 1.
It is 211m long and 8 degrees long.

In general, if you reduce the gap length during recording,
The signal magnetic field leaking from the gear part becomes smaller and the efficiency deteriorates. For this reason, when trying to record on a metal magnetic tape with a large coercive force using a narrow gap head that emphasizes playback characteristics, such as a recording/playback head, the ferrite core material has a low saturation magnetic flux density, so the tape It has the disadvantage of saturation when the signal magnetic flux becomes large. Therefore,
Metallic core materials such as permalloy, sendust, and amorphous soft magnetic materials, which have a higher saturation magnetic flux density than ferrite core materials, are used. However, when the metal core material has a low resistivity and the frequency of the signal magnetic flux flowing through the core becomes high, losses due to eddy currents increase. For this reason, there is a high frequency limit to the bias frequency to be applied, and the bias frequency of the metal core material is generally about 10 to 120 kHy. Therefore, the signal frequency that can be handled during high-speed dubbing is about 1/3 of the bias frequency, which is 30 to 40 k.
Hz is the limit.

However, since the high frequency of normal music tapes is about 16kHz, there was a problem that the dubbing speed could not be increased more than three times.

Purpose of the Invention The purpose of the present invention is to reduce the output voltage of the bias oscillation circuit of a cassette tape recorder with a radio receiver or a cassette tape deck having a high-speed dubbing function, and to reduce the power consumption and size of the device. Along with
The present invention aims to provide a magnetic head that enables dubbing at a higher speed than conventional dubbing speeds.

A magnetic head according to an aspect of the invention has two pairs of magnetic cores each having a coil wound thereon, and the length of the gap between the two pairs of magnetic cores is determined for each pair of the magnetic cores. They are configured to have n different lengths.

DESCRIPTION OF THE EMBODIMENTS FIG. 2 shows an embodiment of the invention applied to a stereo type cassette tape magnetic head.

In Figure 2, the number of coil windings is 4 + 7): 17
51 s/, 6'+6'NFl magnetic f-77) It is installed in the shield case 1 corresponding to the relative position of the trunk, and there is a gap of 6.6' at the part of the core that contacts the magnetic tape.
, 6'', 6''' are formed. And core 5
．． 5', de, 5'' is divided into two pairs of core groups consisting of two adjacent special a, and the gap length is formed with a different length for each pair of cores. That is, the gap is 6.6' and gap 6'', the gap length of 6'' is different. Note that 7.7// is a rolled plate.

Next, a method of using the non-example magnetic head will be described.

FIG. 3 shows the recording tracks for stereo recording of a cassette tape. Tracks 8 and 9 are used when the magnetic tape 14 runs in the direction of arrow 12, track 8 is the left channel, and track 9 is the left channel. It receives the right channel. Similarly, tracks 10 and 11 are used when the magnetic tape runs in the direction of arrow 13. Track 10 is the right channel and track 11 is the left channel.

Now, when trying to reproduce the recorded signals of the recording tracks 8 and 9 while the magnetic case 14 is traveling in the direction of the arrow El]12, the core parts 5 and 5' of the magnetic head with the small gap length are It comes into contact with recording tracks 8 and 9 and performs playback. 1. When recording audio signals on the recording tracks 8 and 9, the magnetic head is rotated 180 degrees and the core portions 5' and 5'' with the long gap are recorded on the tracks 8 and 9.
9 and performs recording. Here, the length of the gap 6.6' of the core part 6.5' that performs reproduction is usually designed to be about 1.2 μm from the relationship with the maximum reproduction frequency.
Ru.

- Gaps 6' and 6" between the core parts 5" and 5" for 10,000 recordings
The length of ' is usually designed to be about 4 to 5 μm. The reason why the core parts 5'', 5'' with a large gap length are used for recording is that the signal magnetic field leaking from the gear can be efficiently recorded through the joists with a large gap length.

Therefore, by using the non-conventional magnetic head, it is possible to reduce the bias current during high-speed dubbing recording compared to the case where a conventional recording/playback head is used, which reduces the power consumption of the device. It has the advantage that it is easy to reduce the size of the device or the size of the device.

Furthermore, by greatly reducing the gap length and increasing the recording efficiency, it becomes possible to use ferrite core material as the recording core material, making it possible to increase the dubbing speed higher than conventional methods. It becomes possible. In other words, since the resistivity of the ferrite core material is extremely thick compared to metal cores, the eddy current loss is extremely small, and is only a few inches thicker than metal cores. It can handle 1000 AC magnetic flux. Therefore, in the magnetic head of this embodiment, a ferrite core is used as the recording core.xf)4
~10x high-speed dubbing will become a reality.

Although the above embodiments have been described with respect to a stereo type magnetic head, it is obvious that the present invention can also be applied to a monaural type magnetic head.

Unfortunately, using the inventive magnetic head requires rotating the head 180 degrees. A mechanism that rotates the playback head of two channels by 180 degrees and achieves auto-reverse playback has already been put into practical use, and there are no problems with the head rotation mechanism.

Effects of the Invention As mentioned above, by using the uninvented magnetic head, there is a radio (cassette tape recorder) having a dubbing function consisting of two tape running sections, a recording/playback section and a playback-only section. It is easy to reduce the power consumption of wart cassette tape decks and downsize the device.Moreover, it is advantageous to use a ferrite core material for the recording core with a large gap length, and the dubbing speed can be kept at a constant speed. This makes it possible to perform this at a speed of 4 to 10 times.Furthermore, in the magnetic head of the present invention, the core position corresponds to the relative position of the trunk on the magnetic tape, and the magnetic head is rotated 180 degrees at the center of rotation. This also has the effect of enabling auto-reverse playback and auto-reverse recording.By making the reproduction-only section into a traveling section capable of auto-reverse playback, auto-reverse dubbing can also be realized.

Furthermore, it also has the advantage of being able to record with good recording characteristics during constant speed recording.

[Brief explanation of the drawing]

Figure 1 is an overview of a conventional recording/playback magnetic head;
The figure is an overview diagram showing an embodiment of the G1 head according to the invention, and FIG. 3 is an overview diagram showing track positions on a cassette tape.

Claims (2)

[Claims] (1) It has two pairs of magnetic cores wrapped with coils,
A magnetic head characterized in that gap lengths of the helad gap portions of the two pairs of magnetic cores are configured to be different lengths for each pair. (2) The magnetic head according to claim 1, wherein the core portion with a large gap length is used for recording, and the core portion with a short gap length is used for reproduction. ('4) The magnetic heald according to claim 1 or 2, characterized in that a ferrite soft magnetic material is used as the head core having a large gap length.