JPH0351704Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in magnetic head devices, and more particularly to complex multi-air gap magnetic flux responsive magnetic head devices.

BACKGROUND OF THE INVENTION Flux-responsive multi-gap magnetic heads are commonly used to detect the magnetization pattern of a magnetic scale and convert it into an electrical signal. This magnetic head usually has a two-channel configuration for discriminating the direction of the magnetic scale or for interpolation within the recording wavelength.

As shown in FIG. 1, the above-mentioned head has conventionally been constructed such that a first channel head 4 and a second channel head 5 each consisting of a plurality of cores 2 are placed one behind the other for a single track magnetic scale 1. Alternatively, the first channel head 6 and the second channel head 7 may be arranged on the magnetic scale 1 of different tracks _T1 and _T2 , respectively.

However, in a conventional magnetic head with such a configuration, when the amplitude (intensity) A of each magnetic grating 8 of the magnetic scale 1 is non-uniform and changes depending on the detection position The amplitudes of the head outputs O ₁ and O ₂ will be different.
This has caused interpolation errors and other errors.

To solve this problem, a method has been proposed, for example, as disclosed in Japanese Patent Publication No. 56-4843, in which the distance between the heads of the constituent channels is shortened so that the pitch error and amplitude change do not affect the interpolation error. ing.

However, in one method, although it is said that there is no interference between channels, the interference cannot be ignored and there is a problem that it is difficult to detect the phase difference according to the set value. According to another method, the number of cores required for the head configuration when n gaps are provided per channel was n+1 in the conventional method, but 2n is required, and as the number of materials increases in the assembly process, A complicated problem arose.

Purpose of the invention The purpose of the present invention is to provide a highly accurate magnetic head device that does not cause interpolation errors even if the amplitude of the magnetic grating on the magnetic scale is not constant.

Another object of the present invention is to provide a magnetic head device having a simpler structure and requiring fewer materials than conventional multi-gap heads.

A further object of the present invention is to provide a magnetic head device having a structure that allows the phase difference between the outputs of each channel to be obtained as set, as compared to the conventional method described above.

Summary of the invention In order to achieve the above-mentioned purpose, the present invention focuses on the fact that the above-mentioned amplitude change period of the magnetic lattice is short, which is longer than multiple wavelengths, and utilizes this to utilize the range of amplitudes that are considered to be approximately the same. In the head unit block of multiple channels, in other words, the same number of cores having approximately equal magnetic potential difference in each channel with respect to the magnetic lattice are arranged in opposite directions, and both ends thereof have equal magnetic potential. The head unit blocks are arranged alternately between channels via a shared core to form a multi-gap head, so that the output amplitude of each channel always changes proportionally. do.

Embodiment The present invention will be further explained below with reference to the embodiment shown in the drawings. First, as shown in FIG. If the magnetic resistance is R and the magnetic flux is φ, this magnetic circuit can be expressed as shown in FIG. Using this method of expression, the configuration of one channel of a conventional multi-gap head is shown in FIG. 5. In addition, these individual magnetic fluxes were added because strength was required for signal extraction and averaging by addition would improve accuracy, and for this reason, the magnetic circuit was configured as shown in Figure 6. . However, in the first channel F _1-i , φ _1-i , R _1-i and in the second channel
They are indicated by F _2-i , φ _2-i , R _2-i (i=1, 2,...n).

FIG. 7 shows the basic magnetic circuit configuration of a head in which the distance between channels is shortened for the above-mentioned purpose according to these examples. Similarly, it is assumed that the magnetic circuit of FIG. 8 is configured based on the configuration of FIG. 6 in order to obtain the magnetic flux additions Σφ _1-i and Σφ _2-i of the first and second channels. However, in such a configuration, the outputs that should be Σφ _1-i and Σφ _2-i are different from these, and the intended purpose cannot be achieved. One reason for this is that adjacent channels with different outputs share the same core.

As a solution to this problem, a core dedicated to each channel may be provided without using a shared core, as shown in FIG. 9, but the conventional example described above had such a configuration.

Now, if we consider the reason why the intended purpose cannot be achieved as described above when a shared core is used as in the magnetic circuit configuration shown in Figs. 7 and 8, we find that in both figures, the magnetic flux φ ₁
The magnetic potential at one end side A is the one-sided magnetic potential of F _1-1 , which should be equal magnetic potentials. This relationship is maintained in the magnetic circuit configurations shown in FIGS. 5 and 6. However, from Figure 7, the connected partner B is given by F _1-1 + F _2-1 , and the original
The magnetic potential on one side of F _1-1 is not equal to the equimagnetic potential. For this reason, when a magnetic circuit as shown in FIG. 8 is connected, the magnetic potential is changed, causing unnecessary magnetic flux to flow and not producing the expected results.

In view of the above-mentioned reasons, the present invention proposes that if the connection points are set at equal magnetic potentials as a basic unit block of one channel, and this is connected to the basic unit blocks of other channels, the above-mentioned malfunction will not occur. It is based on an idea. An example of the basic configuration of a magnetic circuit based on this idea is shown in FIG. In this example, as is clear from the figure, one ends of φ _1-1 and φ _1-2 have equal magnetic potential. The same applies to φ _2-1 and φ _2-2 . Therefore, even if these parts are connected by a magnetic circuit, they will not interfere with each other. FIG. 11 shows an example in which connections are further made to obtain the sum of the magnetic fluxes φ from the example of FIG. 10. In this example, the parts of the magnetic circuit shown in Figure 9 that have equal magnetic potential from the beginning are connected to each other, so there is no interference within one channel or with other channels, and the same as in the example shown in Figure 9. Each unit block operates to obtain the correct sum of magnetic fluxes Σφ ₁ and Σφ ₂
is obtained. In this case, even if there is a slight difference in magnetic potential within one channel (for example, F _1-1 and F _1-2 ), the connection forces the sum of these to become the same magnetic potential, so other channels are forced to have the same magnetic potential. No interference with the channel occurs.

This is not limited to this example, but by arranging the same number of cores with almost equal magnetic potential differences in opposite directions in one channel and using head unit blocks whose both ends have equal magnetic potential, the magnetic potential This is achieved by ensuring that the sum of the values is zero and that no magnetic difference occurs at the ends of adjacent channels. Further, the number of channels is not limited to this example, and a large number of channels can also be used.

To construct the head magnetic circuit of the present invention for an actual magnetic grid, the settings are as follows.

That is, in a unit block of one channel, the distance G ₁ between adjacent gaps is set to 2n-1/2λ, where the magnetic potential differences are opposite. However, n=1, 2... ..., λ is the wavelength.

Further, the distance G ₂ between the gaps between the channels is set so that they are separated by the required phase difference. For example, when a phase difference θ [rad] is required, the distance between the gaps may be (m±θ/2x)λ.

However, m=0, 1, 2,... Figures 12a, b, and c show an embodiment of a two-channel magnetic modulation type head based on the above-described structure of the magnetic circuit of the present invention. In the figure, CH ₁ is the first channel core, H ₀ is the shared core, (H ₂ is the second channel core, H ₃ is the magnetic path material, D ₁ is the first channel detection section, and D ₂ is the second channel detection section. , H ₄ and H ₅ are core holding members, and h is a magnetic scale through hole.

The cores are arranged with respect to the magnetic grid so as to form a magnetic circuit shown in FIG. 11, and are set to form the gap described above.

FIGS. 13a, b, and c show other embodiments in which the core shapes are different, and FIG. 14 shows the core shape in yet another embodiment.

Effects of the invention As is clear from the above explanation, according to the invention, since the head unit block in one channel has a structure with no magnetic potential difference, interference between adjacent channels can be eliminated, and the magnetic grid This prevents interpolation errors from occurring due to non-uniformity. Also, since the core is shared between adjacent channels, the core configuration can be simpler than in conventional multi-gap heads.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing the schematic structure of a conventional detection head, FIG. 3 is a diagram showing its output characteristics, and FIGS. Magnetic circuit configuration diagram of the detection head to be considered,
Figures 10 and 11 are magnetic circuit configuration diagrams of the head of the present invention, Figures 12a, b, and c, Figures 13a,
Figures b, c and 14 are schematic diagrams showing embodiments of the present invention, respectively. CH ₁ , CH ₂ ...first and second channel cores,
H ₀ ... common core, h ... magnetic scale through hole.

Claims (1)

[Scope of utility model registration request] With respect to the magnetic lattice of the magnetic scale, the same number of cores with almost equal magnetic potential differences are arranged in opposite directions in each channel, and head unit blocks with equal magnetic potential at both ends are alternately distributed between each channel via a shared core. A magnetic head device characterized in that it is arranged to form a multi-gap head.