Magnetic sensor device

Patent metadata

Field	Value
Publication number	US-9396366-B2
Application number	US-201314440941-A
Country	US
Kind code	B2
Filing date	Nov 6, 2013
Priority date	Nov 15, 2012
Publication date	Jul 19, 2016
Grant date	Jul 19, 2016

Abstract

A magnetic sensor device includes magnetic detection elements arrayed along a line intersecting the relative movement direction of a medium, and a magnet applying a bias magnetic field to the magnetic detection elements with a line of magnetic force in the constant direction. The magnetic sensor device detects a magnetic field change when a medium with a magnetic pattern passes through the bias magnetic field as an electric signal through the magnetic detection elements and reads the magnetic pattern of the medium. A plurality of reading switches is connected to the respective magnetic detection elements and an output line common to the magnetic detection elements. The magnetic sensor device includes a shift register closing the reading switches sequentially one by one to transfer the outputs from the magnetic detection elements sequentially one by one to the output line.

First claim

The invention claimed is:

1. A magnetic sensor device comprising:
a biasing magnet applying a bias magnetic field to a magnetic detection element with a line of magnetic force in a constant direction;
a plurality of the magnetic detection elements configured to detect a magnetic field change caused by passing of a medium with a magnetic pattern through the bias magnetic field as an electric signal and to read the magnetic pattern of the medium, and arrayed along a reading line intersecting with a relative movement direction of the medium;
a plurality of switches, each of the plurality of switches connected to the respective magnetic detection element of the plurality of magnetic detection elements and to a output line common to the plurality of magnetic detection elements; and
a switch controller closing the plurality of switches sequentially one by one to transfer respective outputs from the magnetic detection elements sequentially one by one to the output line;
wherein the switch controller periodically carries out a reading cycle in synchronization with the relative movement of the medium and at a frequency of a unit feeding time that is a time period at which a relative movement distance of the medium becomes equal to a pitch of the adjacent magnetic detection elements along the reading line, the reading cycle being an operation of transferring the outputs of all magnetic detection elements of the plurality of magnetic detection elements one by one to the output line common to the plurality of the magnetic detection elements.

2. The magnetic sensor device according to claim 1 , wherein for each magnetic detection element:
when the output is within a threshold range determined from an output value of a previous reading cycle, a same value as the output value of the previous reading cycle is output as an output value of a current reading cycle; and
when the output is outside of the threshold range determined from the output value of the previous reading cycle, the output of the current reading cycle is output as an output value thereof.

3. The magnetic sensor device according to claim 1 , wherein the switch controller:
carries out a plurality of the reading cycle within the unit feeding time; and
includes an output arithmetic processor that determines, for each magnetic detection element, an output value in the unit feeding time based on outputs of the plurality of the reading cycles in the unit feeding time.

4. The magnetic sensor device according to claim 3 , wherein the output arithmetic processor outputs an average value of the outputs of the plurality of the reading cycles in the unit feeding time as an output value in the unit feeding time.

5. The magnetic sensor device according to claim 3 , wherein when the outputs of the plurality of the reading cycles in the unit feeding time:
increases monotonically, the output arithmetic processor outputs a maximum value of the outputs in the unit feeding time as an output value in the unit feeding time;
decreases monotonically, the output arithmetic processor outputs a minimum value of the outputs in the unit feeding time as the output value in the unit feeding time; and
contains a local maximum value or a local minimum value, the output arithmetic processor outputs the local maximum value or the local minimum value in the unit feeding time as the output value in the unit feeding time.

6. The magnetic sensor device according to claim 5 , wherein the output arithmetic processor calculates the output value by replacing an output of the reading cycle with a latest moving average of the reading cycle for each magnetic detection element.

7. The magnetic sensor device according to claim 3 , wherein the output arithmetic processor:
calculates an average value of the outputs of the plurality of the reading cycles in the unit feeding time;
outputs the average value as an output value in the unit feeding time when all outputs of the plurality of the reading cycles in the unit feeding time are within a predetermined range relative to the average value; and
outputs an output having a most apart value from the average value as the output value in the unit feeding time when among the outputs of the plurality of the reading cycles in the unit feeding time there exists an output data being outside of the predetermined range relative to the average value.

8. The magnetic sensor device according to claim 3 , wherein the output arithmetic processor:
outputs the output value in the previous unit feeding time as an output value in the unit feeding time when all outputs of the plurality of the reading cycles in the current unit feeding time are within a predetermined range from the output value in the previous unit feeding time; and
outputs an output having a most apart value from the output value in the previous unit feeding time as the output value in the unit feeding time when among the outputs of the plurality of the reading cycles in the unit feeding time there exists an output being outside of the predetermined range relative to the output value in the previous unit feeding time.

9. The magnetic sensor device according to claim 1 , further comprising an output adjuster determining a center value of an output value range to be an output value of the magnetic detection element when there is no magnetic pattern at a reading position of the magnetic detection element and adjusting an output value of the magnetic detection element to a positive or negative value around the center value.

10. The magnetic sensor device according to claim 1 , further comprising an output adjuster determining a reference to be an offset voltage of an output from the magnetic detection element, and outputting an absolute value of a difference between an output value of the magnetic detection element and the reference as the output value of the magnetic detection element.

11. A magnetic sensor device, comprising:
a biasing magnet applying a bias magnetic field to a magnetic detection element with a line of magnetic force in a constant direction;
a plurality of the magnetic detection elements configured to detect a magnetic field change caused by passing of a medium with a magnetic pattern through the bias magnetic field as an electric signal and to read the magnetic pattern of the medium, and arrayed along a reading line intersecting with a relative movement direction of the medium;
a plurality of switches, each of the plurality of switches connected to the respective magnetic detection element of the plurality of magnetic detection elements and to a output line common to the plurality of magnetic detection elements; and
a switch controller closing the plurality of switches sequentially one by one to transfer respective outputs from the magnetic detection elements sequentially one by one to the output line;
wherein the switch controller periodically carries out a reading cycle in synchronization with the relative movement of the medium, the reading cycle being an operation of transferring the outputs of all magnetic detection elements of the plurality of magnetic detection elements one by one to the output line common to the plurality of the magnetic detection elements; and
for each magnetic detection element:
when the output is within a threshold range determined from an output value of a previous reading cycle, a same value as the output value of the previous reading cycle is output as an output value of a current reading cycle; and
when the output is outside of the threshold range determined from the output value of the previous reading cycle, the output of the current reading cycle is output as an output value thereof.

12. The magnetic sensor de

Assignees

• Mitsubishi Electric Corp

Inventors

• Ogomi Tomokazu
• Arimoto Hironobu
• Yamanaka Satoshi
• Makabe Kazuya

Classifications

• G01R33/10

  Plotting field distribution {; Measuring field distribution} · CPC title

• G01R33/0094

  Sensor arrays · CPC title

• G06K7/088 Primary

  using magneto-sensitive switches, e.g. reed-switches · CPC title

• G06K7/087

  flux-sensitive, e.g. magnetic, detectors (G06K7/10336 takes precedence) · CPC title