Magnetic encoder

A technology of magnetic encoder and magnetic sensor, applied in the field of magnetic encoder, can solve the problems of low power consumption and high resolution, etc.

Inactive Publication Date: 2007-04-04
HITACHI METALS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

SVGMR components are not used in magnetic encoders because they can hardly meet the high resolution required by the market
However, since SVGMR elements exhibit the same magnetoresistance change rate as coupled GMR elements

Method used

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Examples

Experimental program
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example 1

[0042] Figure 1 shows a perspective schematic diagram explaining a magnetic encoder with SVGMR elements. The magnetic encoder 1 consists of a magnetic medium 2 and a magnetic sensor 6 . On the magnetic medium 2, two magnetized regions magnetized opposite to each other, ie, a first magnetized region 21 and a second magnetized region 22, are continuously and alternately arranged along the extending direction of the medium. In the following explanation, it is assumed that the length λl of the first magnetized region 21 is longer than the length λs of the second magnetized region 22 . In the magnetic sensor 6, a plurality of SVGMR elements 5 are formed in a rectangular plane extending perpendicularly to the extending direction of the magnetic medium 2 on the base material 4, and the ends of the SVGMR elements 5 are connected to the flexible printed circuit 3 by wires (not shown). The magnetic medium 2 faces the SVGMR element 5 having a rectangular plane through a predetermined ga...

example 2

[0047] Referring to FIG. 4, in which the first magnetized region length λl is longer than the second magnetized region length λs on the magnetic medium 2, the operation of the magnetic encoder will be described. 4A illustrates the positional relationship between the SVGMR elements 51a to 52b of the magnetic sensor 6 and the magnetic medium 2, and FIGS. The resistance diagrams of the SVGMR element 51a of the first sensor 51, the other SVGMR element 51b of the first sensor 51, the first sensor 51 consisting of SVGMR elements 51a and 51b, and the second sensor 52 consisting of SVGMR elements 52a and 52b are shown respectively In Figures 4B, 4C, 4D and 4E. In the magnetic sensor 6, four SVGMR elements 51a to 52b are provided on a base material. Each SVGMR element has a cell width w, and the SVGMR elements in each sensor are at a distance λ from each other. The second sensor 52 is translated by λ / 2 behind the first sensor 51 . Arrows superimposed on each SVGMR element indicate t...

example 3

[0053] Referring to FIGS. 6A to 6F , a magnetic encoder of Example 3 will be described, which is similar to the magnetic encoder of Example 2 shown in FIG. 4A except that the magnetic medium 2 has a first region length shorter than a second magnetized region length. 6A illustrates the positional relationship between the SVGMR elements 51a to 52b of the magnetic sensor 6 and the magnetic medium 2, and FIGS. The resistance diagrams of the SVGMR element 51a of the first sensor 51, the other SVGMR element 51b of the first sensor 51, the first sensor 51 consisting of SVGMR elements 51a and 51b, and the second sensor 52 consisting of SVGMR elements 52a and 52b are shown respectively In Figures 6B, 6C, 6D and 6E. In the magnetic sensor 6, four SVGMR elements 51a to 52b are provided on a base material. Each SVGMR element in each sensor has a cell width w, and the SVGMR elements in each of the first and second magnetization sensors are at a distance λ from each other. The second sens...

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Abstract

A magnetic encoder having a magnetic sensor composed of SVGMR elements, in which a signal output with a half of a cycle of magnetic regions on a magnetic medium. The magnetic encoder comprises the magnetic medium, on which first magnetic regions and second magnetic regions are oppositely magnetized along the medium extending and disposed successively and alternately with each other, and the magnetic sensor that has an even number of SVGMR elements and is movable relatively to the medium along the medium extending. Magnetizations of pinned magnetization layers of all the SVGMR elements are directed in a same direction along the medium extending. Each of the even number of SVGMR elements in the magnetic sensor is apart by a half of the sum of a first magnetic region length plus a second magnetic region length from each other along the medium extending, and the even number of SVGMR elements are connected in series so that a cycle of resistance change of the magnetic sensor is a half of a cycle length of the first and the second magnetic regions on the medium and the signal output with high resolution can be obtained.

Description

technical field [0001] The present invention relates to a magnetic encoder using a magnetic sensor with a spin valve type giant magnetoresistance effect film. Background technique [0002] In recent years, magnetic encoders applied to consumer equipment such as small robots, digital cameras, and inkjet printers have been required not only to be inexpensive and miniaturized, but also to have high resolution and excellent gap output characteristics. In other words, a magnetic encoder is required to be miniaturized but not require a processing circuit for doubling the signal frequency, and also maintain a stable output during its operation against gap variations. Furthermore, low electric power consumption is required. [0003] In a conventional magnetic encoder, a magnetoresistor formed of an anisotropic magnetoresistance effect film (hereinafter referred to as "AMR element") is used. AMR elements are widely used because even in a relatively small magnetic field region, the ...

Claims

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Application Information

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IPC IPC(8): G11B5/02G11B5/09G11B5/39G01R33/09H01L43/08H03K17/97
Inventor 阿部泰典仁平裕治
Owner HITACHI METALS LTD
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