JPH11218568A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic sensor with high accuracy and a wide application range. SOLUTION: In the magnetic sensor provided with an electric field emission type emitter electrode 1 arranged to emit a linear electron beam into a package 8 evacuated inside, a gate electrode 2 controlling the number of electrons emitted from the emitter electrode 1, anode electrodes 3 provided dividedly at least in two via an insulator layer on the substrate 5 and collecting electrons of the electron beam and a bias electrode 4 biasing the electron beam and detecting the intensity of the external magnetic field base on the variation of electron number coming in the anode electrode 3 due to the external magnetic field of the measuring object, a mask 9 limiting the linear electron beam shape is provided between the emitter electrode 1 and the anode electrodes 3. By this, an electron beam with always uniform arm length and beam width is obtained and the accuracy is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor used for a control element of a brushless motor.

[0002]

2. Description of the Related Art A magnetic sensor typified by a semiconductor Hall element is one of the important sensors indispensable in fields such as home electric appliances and industrial machines, such as a control element in a brushless motor, and is applied with higher sensitivity. The development of a magnetic sensor having a wide range is desired. Since the sensitivity of a semiconductor magnetic sensor depends on the mobility of electrons in the semiconductor, attempts have recently been made to use a cold-cathode solid-state vacuum device based on the principle of electric field emission as a magnetic sensor as a measure to improve sensitivity. Have been done. Further, it is said that this device can be used even in a high temperature or radioactive environment, and its application range can be expected to be expanded (Japanese Patent Laid-Open No. 6-308207). FIG. 14 shows a typical example of such an apparatus. A vertical field emission type emitter electrode 1 provided on an insulating or semi-insulating substrate 5 for emitting electrons, and for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current. It comprises a gate electrode 2, a deflection electrode 4 for controlling the trajectory of electrons emitted from the emitter electrode 1, and an anode electrode 3 for collecting electrons emitted from the emitter electrode 1. Note that the device is manufactured using a semiconductor process.

[0003]

However, such a conventional magnetic sensor has the following problems. (1) In a conventional magnetic sensor, a linear output characteristic with respect to a magnetic field is obtained by making an electron beam have a uniform line width. However, a linear electron beam is formed by arranging an emitter electrode in a line. Since the electron beam is generated, the line width of the electron beam fluctuates, and the output of the sensor exhibits a non-linear characteristic with respect to an external magnetic field, thereby lowering the accuracy of the present device and narrowing the applicable range. (2) In the conventional magnetic sensor, if the arm length of the linear electron beam is uniform, a linear output characteristic with respect to the magnetic field is obtained. Not provided. Therefore, the length of the arm of the electron beam fluctuates due to fluctuations in the electric field emission current, etc., and the characteristics of the sensor output with respect to an external magnetic field exhibit non-linearity. (3) In the conventional magnetic sensor, the function is satisfied because the divided deflection electrode and the gate electrode are insulated from each other. However, when actually used, insulation between each deflection electrode and the gate electrode is reduced. This is considered to be because the electron beam ionizes the atmospheric gas and is attracted to the emitter electrode by electrostatic attraction, thereby modifying the surface of the insulating layer located above the emitter electrode. When the insulation between each deflection electrode and the gate electrode is reduced, the potential of the gate electrode is reduced and the amount of emitted electrons is reduced, so that the sensor cannot be measured, reliability is impaired, and the applicable range is narrowed. (4) In a conventional magnetic sensor, an electron beam has a uniform line width, so that a linear output characteristic with respect to a magnetic field is obtained. However, since a linear electron beam is generated by a deflection electrode, an electric field The line width of the electron beam fluctuates due to the non-uniformity of the electron beam, and the electron beam exhibits a non-linear characteristic, lowering the accuracy of the device and narrowing the applicable range. Therefore, an object of the present invention is to provide a magnetic sensor with high accuracy and a wide range of application.

[0004]

In order to achieve the above object, the present invention provides a field emission type emitter electrode arranged to emit a linear electron beam in a package whose inside is evacuated; A gate electrode for controlling the number of electrons emitted from the substrate, an anode electrode for collecting electrons of the electron beam provided at least in two parts on a substrate via an insulating layer, and a deflection for deflecting the electron beam An electrode, and a magnetic sensor that detects the intensity of the external magnetic field based on a change in the number of electrons incident on the anode electrode due to the external magnetic field of the measurement target, between the emitter electrode and the anode electrode, A mask for limiting the shape of the linear electron beam is provided. Further, an insulating layer between the deflection electrode and the gate electrode is removed.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below based on examples. First Embodiment FIG. 1 is a perspective view showing the entire configuration of a magnetic sensor according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the vicinity of an emitter electrode, and FIG.
FIG. 4 is a plan view of the vicinity of the emitter electrode as viewed from above. The magnetic sensor according to the present embodiment includes a field emission type emitter electrode 1 provided for emitting electrons into a package 8;
A gate electrode 2 for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current;
Electrode 3 for collecting electrons emitted from
And a deflection electrode 4 for controlling the trajectory of electrons emitted from the emitter electrode 1. further,
A start-up correction mask 9 made of an insulator is laminated on each deflection electrode. The deflection electrode 4 is equally divided into four sections at 90 ° around the emitter electrode 1.
The same potential is applied to these deflection electrodes 4. The anode electrode 3 is viewed from above the sensor,
The anode electrode 3 is divided into four at the same position as the deflection electrode 4. By measuring the current reaching each anode electrode 3, the arrival position of the cross-deflected electron beam reaching the anode electrode 3 can be determined. Perimeter 360 of these structures
An equipotential shielding electrode 7 is provided each time. All the electrodes described above are arranged radially and symmetrically from the center of the cross-shaped electron beam so that the electron orbit does not have anisotropy. Here, in the conventional structure as shown in FIG. 14, the arm length of the electron beam has a non-uniform arm length with time as shown in FIGS. 4B and 4C, for example. Since the beam becomes a cross-shaped electron beam, the output with respect to the external magnetic field becomes non-linear as shown by the broken line in FIG. However, if a mask for limiting the edge of the electron beam is provided as shown in FIGS. 1 and 2 of this embodiment, the edge is limited by the mask as shown in FIG. Since an electron beam having the arm length of the electron beam is obtained, a linear output with respect to an external magnetic field can be obtained as shown by a solid line in FIG.

Second Embodiment FIG. 6 is a perspective view showing the overall configuration of a magnetic sensor according to a second embodiment of the present invention. The appearance of the magnetic sensor of this embodiment is the same as that of FIGS. An emitter electrode 1 provided for emitting electrons, a gate electrode 2 for limiting the number of electrons emitted from the emitter electrode 1, that is, an emitter current, and an electron emitted from the emitter electrode 1 are collected. An insulator 6 is laminated in place of the deflecting electrode 4 at the position of the anode electrode 3 and the deflecting electrode 4 provided in the first embodiment. The mask 9 is held and fixed. These components are arranged in a package 8 and, similarly to the first embodiment, an equipotential shielding electrode 7 is provided at 360 degrees on the outer periphery of these structures. Also in this embodiment, by providing a mask,
Since an electron beam having a uniform beam length is always obtained, an improvement in the linearity of the sensor output with respect to an external magnetic field similar to the solid line in FIG. 5 can be seen.

Third Embodiment FIG. 7 is a perspective view showing the entire configuration of a magnetic sensor according to a third embodiment of the present invention, and FIG. 8 is an enlarged sectional view showing the vicinity of an emitter electrode. The magnetic sensor according to the present embodiment includes a field emission type emitter electrode 1 provided for emitting electrons, a gate electrode 2 for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current, An anode electrode 3 for collecting electrons emitted from the emitter electrode 1 and a deflection electrode 4 arranged on the same plane as the gate electrode for controlling the trajectory of the electrons emitted from the emitter electrode 1. I have.
Further, a mask 9 for correcting the trajectory made of an insulating material is laminated on each deflection electrode. These components are arranged inside the package 8 as shown in FIG.
The deflection electrodes 41 and 42 are arranged around the emitter electrode 1.
It is equally divided into 90 degrees and divided into four parts. The same potential is applied to these deflection electrodes 41 and 42. The anode electrode 3 is divided into four at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the cross-deflected electron beam reaching the anode electrode 3 can be determined. An equipotential shielding electrode 7 is provided at 360 degrees on the outer periphery of these structures. Here, in the conventional structure as shown in FIG. 14, since the line width of the electron beam is not constant, the state when the electron beam reaches the anode electrode 3 is a non-uniform line as shown in FIG. It becomes a cross-shaped electron beam having a width, and the output with respect to the external magnetic field becomes non-linear as shown by the broken line in FIG. However,
If the masks 91 and 92 for correcting the trajectory are provided as shown in FIGS. 7 and 8 of this embodiment, a cross-shaped electron beam having a uniform line width can be obtained as shown in FIG. 9B. Therefore, a linear output can be obtained with respect to an external magnetic field as shown by the solid line in FIG. Note that when a conductor is used as a mask, the conductor may be provided over the insulating layer 9.

Fourth Embodiment FIG. 11 is a perspective view showing the overall configuration of a magnetic sensor according to a fourth embodiment of the present invention. In the magnetic sensor of the present embodiment, five emitter electrodes 1 provided for emitting electrons are arranged in a cross shape, and a gate electrode for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current is controlled. 2, an anode electrode 3 for collecting electrons emitted from the emitter electrode 1, and a deflection electrode 4 on the same plane as the gate electrode 2 for controlling the trajectory of the electrons emitted from the emitter electrode 1. It is configured. Further, a trajectory correcting mask 9 made of an insulating material is laminated on each deflection electrode 4. These components are arranged inside the package 8 as shown in FIG.
Are arranged as shown in FIG. The deflection electrode 4 is equally divided into 90 degrees and divided into four parts around the emitter electrode 1. The same potential is applied to these deflection electrodes 4. The anode electrode 3 is located at the same position as the deflection electrode 4 when viewed from above the sensor.
Is divided into four. By measuring the current reaching each anode electrode 3, the arrival position of the cross-deflected electron beam reaching the anode electrode 3 can be determined. An equipotential shielding electrode 7 is provided at 360 degrees on the outer periphery of these structures. Also in this embodiment, by providing the trajectory correcting mask 9 as in the third embodiment, a cross-shaped electron beam having a uniform line width as shown in FIG. 9B can be obtained. FIG.
As shown by a solid line of 0, a linear output can be obtained for an external magnetic field. Similar effects can be obtained by providing a mask 9 around each of the emitter elements 1 as shown in FIG.

Fifth Embodiment FIG. 13 shows the structure of a magnetic sensor according to a fifth embodiment of the present invention. FIG. 13 is a sectional view taken along a line AA 'of FIG. It is the expanded sectional view.
The appearance is almost the same as that of the conventional example shown in FIG. The magnetic sensor according to the present embodiment includes a field emission type emitter electrode 1 provided for emitting electrons, a gate electrode 2 for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current, The anode electrode 3 for collecting electrons emitted from the emitter electrode 1 and the deflection electrode 4 are arranged on the same plane as the gate electrode 2 for controlling the trajectory of the electrons emitted from the emitter electrode 1. ing. These components are arranged inside the package 8 as shown in FIG. The deflection electrode 4 is equally divided into 90 degrees and divided into four parts around the emitter electrode 1. The same potential is applied to these deflection electrodes 4. The anode electrode 3 is divided into four at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the cross-deflected electron beam reaching the anode electrode 3 can be determined. An equipotential shielding electrode 7 is provided at 360 degrees on the outer periphery of these structures. Here, in the conventional structure as shown in FIG. 15, the deflection electrode electrodes 41 and 42 divided by the insulation deterioration of the exposed portion of the insulating layer 6 become electrically common with the gate electrode 2, and the potential of the gate electrode 2 becomes higher. And the amount of emitted electrons decreases. Therefore, by exposing the exposed portion with buffered hydrofluoric acid or the like and forming it as shown in FIG. 13, the deterioration of the insulating layer can be avoided and the potential fluctuation of the gate electrode 2 can be prevented. Further, overetching is preferable because deterioration of the insulating layer can be further prevented.

[0010]

As described above, according to the present invention,
The following effects are obtained. (1) A linear electron beam emitted from a vertical field emission type emitter electrode is provided with a trajectory correction mask for correcting the end and the line width of the electron beam so that the arm length and the line width are uniform. An electron beam can be obtained. further,
Since the fluctuation of the current flowing into the divided anode becomes linear due to the fluctuation of the external magnetic field, the accuracy of the magnetic sensor is improved, and a magnetic sensor with high accuracy, high practicability and a wide application range can be provided. (2) Since the divided insulating layer between the deflection electrode and the gate electrode is removed and the insulation between the deflection electrode and the gate electrode can be prevented from deteriorating, the potential fluctuation of the gate electrode can be prevented. Thus, the reliability of the magnetic sensor is improved, and a magnetic sensor having a wide range of application can be provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall configuration of a magnetic sensor according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view near an emitter electrode of the first embodiment.

FIG. 3 is a plan view of the vicinity of an emitter electrode of the first embodiment as viewed from above.

FIG. 4 is a schematic diagram illustrating an electron beam when it reaches an anode, viewed from above, for explaining a first embodiment;

FIG. 5 is a characteristic diagram of an external magnetic field and a sensor output for explaining the first embodiment.

FIG. 6 is a perspective view showing an overall configuration of a magnetic sensor according to a second embodiment of the present invention.

FIG. 7 is a perspective view showing an overall configuration of a magnetic sensor according to a third embodiment of the present invention.

FIG. 8 is an enlarged sectional view near an emitter electrode of a third embodiment.

FIG. 9 is a schematic view of a cross-shaped electron beam for explaining the second and third embodiments of the present invention, as viewed from above.

FIG. 10 is a characteristic diagram of an external magnetic field and a sensor output for explaining the second and third embodiments of the present invention.

FIG. 11 is a perspective view showing an overall configuration of a magnetic sensor according to a fourth embodiment of the present invention.

FIG. 12 is a perspective view showing the overall configuration of another example of the fourth embodiment of the present invention.

FIG. 13 is an enlarged sectional view showing the configuration of a magnetic sensor according to a fifth embodiment of the present invention.

FIG. 14 is a perspective view showing the entire configuration of a conventional magnetic sensor.

FIG. 15 is a perspective view showing the overall configuration of a conventional magnetic sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Emitter electrode 2,21,22 Gate electrode 3,31,32 Anode electrode 4,41,42 Deflection electrode 5 Substrate 6,61,62,63,64 Insulating layer 7 Shielding electrode 8 Package 9,91,92,93, 94 Orbit Correction Mask

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Uemura, Inventor 2-1, Kurosaki Shiroishi, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Prefecture

Claims (2)

[Claims] 1. A field emission type emitter electrode arranged to emit a linear electron beam in a package having a vacuum inside, a gate electrode for controlling the number of electrons emitted from the emitter electrode, and a substrate. An anode electrode for collecting electrons of the electron beam, which is provided at least divided into two parts via an insulating layer, and a deflection electrode for deflecting the electron beam, wherein the anode electrode is provided by an external magnetic field to be measured. A magnetic sensor for detecting the intensity of the external magnetic field based on a change in the number of electrons incident on the magnetic field, wherein a mask for limiting the shape of the linear electron beam is provided between the emitter electrode and the anode electrode. A magnetic sensor comprising: 2. The magnetic sensor according to claim 1, wherein an insulating layer between the deflection electrode and the gate electrode is removed.