JPH01241012A - Recording and reproducing head - Google Patents

Abstract

PURPOSE:To improve the recording and reproducing efficiency of the title head and, at the same time, to improve the productivity of the device by constituting the head in such a thin film head that head gaps of plural channels are aligned in one line and the head gap length of one channel is different from that of the other channel. CONSTITUTION:The gap length L1 of a channel 1 is shorter than the gap length L2 of another channel 2. The head of the channel 1 is used for reproduction exclusively and and the head of the channel 2 is used for recording exclusively. In this thin film head, the heads having different gap lengths are constituted on one base plate 11 in such way. Since the gaps of the heads which are respectively used for recording and reproduction exclusively are aligned in one line in such way, recording and reproduction can be performed accurately at desired positions by linearly moving the head and a magnetic medium relatively to each other. Therefore, the performance of the head is easily improved and the cost of the head can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording/reproducing head for magnetically recording and reproducing information on a magnetic medium.

In conventional magnetic recording, it is desirable to set the gap length of the recording head and the gap length of the reproducing head to different values in order to perform efficient recording and reproduction.

Regarding recording, it is generally known that the magnetic field generated near the head is expressed by the following equation.

1L H((1)=4NIαtan (2a) where, H(+1): Magnetic field above the gap at a point d away from the head surface N: Coil winding α: Head efficiency L: Gap length I: Recording current Also, magnetic To saturate a medium, a magnetic field equal to the coercive force of the magnetic medium is required at a depth of 1/4 of the recording wavelength from the surface of the magnetic medium.Therefore, the longer the recording wavelength, the deeper the magnetic field. A strong magnetic field is required.In other words, as is clear from the above equation, the recording wavelength is long and the recording depth d
The larger the gap length, the more advantageous it becomes.

Regarding reproduction, the following approximate expression is known as the relationship between reproduction loss and gap length.

Here, LG: Reproduction loss (dB) λ: Recording wavelength As is clear from the above equation, the shorter the gap length, the smaller the reproduction loss LG.In this way, in the case of recording, the gap length is set large, and the reproduction In this case, efficient recording and reproduction can be performed by making the gap length small. In recent years, in the field of image recording, there has been an increasing demand for higher image quality, and the recording bandwidth has tended to become wider. To meet this requirement, dedicated heads with different gap lengths have been used for recording and reproduction.

Problems to be Solved by the Invention However, using a dedicated head in this manner poses a difficult problem in terms of the configuration of the device.

For example, in the case of a home VTR such as VB2, if dedicated heads are used for recording and playback, at least four heads must be attached to the cylinder. Furthermore, the protrusion amount, installation height, and azimuth of each head had to be adjusted, resulting in low productivity and high costs.

Similarly, in magnetic disk devices such as electronic still cameras, the mounting height and height of the recording and playback heads vary.
The problem was that the posture, azimuth, etc. had to be adjusted individually, resulting in low productivity and high cost.

In view of these problems, the present invention provides an inexpensive recording and reproducing head that can perform recording and reproducing efficiently and without reducing the productivity of the device.

Means for Solving the Problems The present invention provides a thin film head in which the head gaps of a plurality of channels are aligned on the same straight line, and the head gap length of at least one channel among the plurality of channels is the head gap length of another channel. They have different configurations.

According to the above-described structure, a channel having a gap length optimal for recording and a channel having a gap length optimal for reproduction can be configured in one head, and those gaps are arranged on the same straight line. Therefore, the optimum channel can be easily accessed at the desired position during recording or playback.

Embodiment FIG. 4 is a perspective view of a two-channel recording/reproducing head according to an embodiment of the present invention, with one channel 2 cut away to illustrate the inside. 110 is a substrate on which a magnetic head is formed by a thin film process. 121,13
1 is a magnetic core that constitutes the head of channel 1;
122 and 132 are magnetic cores forming the head of channel 2. 172 is a coil. 140 is a protective film layer, and 150 is a cover plate.

FIG. 1 is a plan view of the front end surface of the recording/reproducing head of this embodiment as viewed from the Z direction in FIG. 4. In Figure 1, 1
Gap layers 61 and 162 form gaps between the heads of the respective channels. In this embodiment, the gap length L1 of channel 1 is shorter than the gap length L2 of channel 2. That is, the head of channel 1 is used only for reproduction, and the head of channel 2 is used only for recording.

With a thin film head, it is possible to construct heads with different gap lengths on one substrate as described above, and the manufacturing process thereof will be briefly explained below with reference to FIGS. 2 and 3.

FIG. 2 is a sectional view of the channel 1 viewed from the X direction in FIG. 4. First, the lower core 121 is formed on the substrate 110 by sputtering. Next, a gap layer 181 is formed by sputtering. The gap length L1 can be easily controlled by managing the sputtering time of the gap layer 161. Furthermore, after forming the coil 171, the upper core 131 is formed. After that, the protective film layer 14
0 is formed by sputtering, and after its surface is smoothed, a cover plate 150'i is bonded. The substrate 110 and the cover plate 150 are made of ferrite, the upper and lower cores 121 and 131 are made of sendust or permalloy, and the gap layer 161 and the protective film layer 1 are made of ferrite.
40 is made of 5i02, and the coil 171 is made of copper. The structure of channel 2 is also similar.

Now, in order to make the gap lengths of channels 1 and 2 different as in this embodiment, a mask is applied to channel 1 during gap layer sputtering as shown in FIG. make it stop. After that, only the gap layer 162 of channel 2 is grown. In this way, by controlling the gap layer sputtering time four times each for channel 1 and channel 2, it is possible to easily form the optimum gap length for recording and reproduction in each channel.

Incidentally, when the recording/reproducing head of this embodiment is applied to an electronic still camera, which is a magnetic disk device, the gap length L1 of channel 1, which is dedicated to reproduction, is about 0.1 μm, and the gap length L2, of channel 2, which is dedicated to recording, is 0. .3～
0.5 μm is good.

As described above, the recording/reproducing head of this embodiment is characterized in that the gaps of the channels dedicated to recording and reproduction are aligned on the same straight line. Recording or playback can be performed at any desired location.

FIGS. 5 to 7 are diagrams illustrating the operation of a magnetic disk device in which the recording/reproducing head of this embodiment is used. In FIGS. 6 and 7, 1° is the recording/reproducing head of this embodiment, 20 is a base on which the head is mounted, and 30 is a magnetic disk. The magnetic disk 30 rotates in the direction of arrow R. When recording a signal on the magnetic disk 30, a signal current is applied to channel 2 to write a recording pattern 4o on the magnetic disk 30 as shown in FIG. When reproducing a signal, the recording/reproducing head 10 is moved in the direction of the arrow M in FIG. 6 to access the gap of channel 1 on the recording pattern 4o as shown in FIG. 7 and read the signal. Since the recording/reproducing head 10 is simply moved linearly during recording and reproducing in this way, the state of contact between the magnetic disk 3o and the recording/reproducing head 10 does not change during recording and reproducing, and the azimuth also does not change. It does not change.

As described in detail, according to the present invention, recording and reproduction can be performed with a single head at the respective optimal gap lengths, making it easy to improve the performance of magnetic recording and reproducing devices at low cost. It has become possible to realize this, and its practical effects are great.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the tip of a recording/reproducing head in an embodiment of the present invention, FIG. 2 is a sectional view of the same embodiment, FIG. 3 is a flowchart explaining the manufacturing process of the embodiment, and FIG. The figure is a partially cutaway perspective view of the same embodiment, and FIGS. 6 and 7 are schematic diagrams for explaining the operation when the recording/reproducing head of the same embodiment is used in a magnetic disk device. 110...Substrate, 121, 122...
Lower core, 131.132... Upper core, 14
0-... Protective film layer, 160... Cover plate, 161, 182... Gap layer, Ll, L
2...Gap length. Name of agent: Patent attorney Toshio Nakao and 1 other person
0- Mu Shu +2/---Sui Soel 1 lower core +22--Sui Sonel 2 lower core 131--4- P Soel 1 Upper Edict Core 132- Sui Soel 2 and Japanese core +40- Protective film layer L2--Sui base 2 thickness Fig. 1/10--1 group removal +21--Single part core 1.91--Single part core +40--Ichiho I 111 layer l50- Cover removal 161- Knurled 1 171---Coil Ll---Gisep length Fig. 2 Fig. 3 Fig. 4 Fig. 5 wLG Fig. 7

Claims (1)

[Claims] A thin film head having a plurality of channels, the head gaps of the plurality of channels being aligned on the same straight line, wherein the head gap length of at least one channel among the plurality of channels is the head gap length of the other channel. A recording/playback head characterized by being different from the above.