JPS6184502A - Differential type position sensor using hall element - Google Patents

Abstract

PURPOSE:To simplify the structure of the differential type position sensor and to protect Hall element and a permanent magnet mechanically by fixing the permanent magnet and Hall element to a body and moving a core together with the object of a measurement. CONSTITUTION:The permanent magnet 3 and Hall element 4 are fixed to the body 2. The core 1 is provided movably between guide walls 6 of the body 2. Stepped grooves slanting to a movable shaft is formed in the core 1. When the distances between the right and left internal walls of the core 1 and Hall element 4 are equal to each other, magnetic flux piercing the Hall element 4 from left to right is balanced and no output is generated. When the core 1 moves and either of the right and left internal wall of the core 1 comes closer to the Hall element, magnetic flux from the closer wall increases and the differential output corresponding to the movement distance of the core is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a position sensor using a Hall element, and particularly to a position sensor that can obtain differential magnetic flux with one Hall element.

[Background of the invention]

As described in Japanese Patent Application Laid-Open No. 10155/1983, a position sensor using a conventional Hall element to obtain differential magnetic flux has a magnet that moves integrally with the object to be measured, A known method is to form two magnetic circuits using two U-shaped magnetic yokes arranged, insert a Hall element into each yoke, and differentially process the output voltages of the two Hall elements. However, no consideration was given to the number of Hall elements or the mechanical protection of the permanent magnets.

[Purpose of the invention]

An object of the present invention is to provide a position sensor that has a relatively simple structure and can obtain differential magnetic flux using a single Hall element.

[Summary of the invention]

The feature of the present invention is that the direction and magnitude of the magnetic flux passing through the Hall element are changed by the movement of the core. only reacts to the direction and strength of magnetic flux,
This takes advantage of the fact that if the direction of magnetic flux changes, the opposite output can be obtained.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross-sectional view of the core 1 in the movable axis direction, and FIG. 2 shows a cross-sectional view in the direction perpendicular to the movable axis.

A permanent magnet 3 is fixed in the body 2, and a Hall element 4 is fixed between the element fixing walls 5 of the body directly above the permanent magnet, preferably on the neutral line of magnetic flux. The core is made of magnetic material and is connected to the first part by the guide wall 6 of the body.
In the figure, it is configured to move only in the direction perpendicular to the page (in the left-right direction in FIG. 2). As shown in FIG. 3, the grooves in the core are grooved at an angle with respect to the movable axis and have the same width, and are stepped in order to prevent the magnetic flux from taking a shortcut.

The magnet has N and S poles at the top and bottom, and the reason there is a gap 7 between the core and the element fixing wall is to prevent the magnetic flux from flowing directly upward and not reacting to the Hall element. .

As shown in Figure 2, the operation is defined as 0 when the Hall element is located at the center of the left and right walls inside the core and is not affected by magnetic flux.For example, in Figure 1, when the core moves to the right, In this case, as shown in Figure 4, the left side of the inner wall of the core approaches the element fixing wall, and the magnetic flux flows as shown in Figure 4, creating a magnetic flux that crosses the Hall element from the right to the left in the paper. I get the output. If the output at this time is positive, the core is the first
When moving to the left in the diagram, the right side of the inner wall of the core approaches the element fixing wall, and the magnetic flux easily passes in the direction bent to the right, contrary to Figure 4, moving the Hall element from the left to the right. The transverse magnetic flux produces the opposite negative output.

According to this embodiment, the Hall element and the permanent magnet can be protected from mechanical force, and the durability and reliability are excellent.
A position sensor that can obtain differential magnetic flux can be obtained with one permanent magnet and one Hall element.

〔Effect of the invention〕

As described in detail above, according to the present invention, the structure is such that differential magnetic flux is obtained by moving the core position, so the portion of the Hall element with good linearity of the magnetic flux density-output characteristic can be used, and the Hall element It is also possible to utilize the fact that the magnetic flux passing through the element is balanced on the left and right sides so that it does not substantially feel magnetic, so it is possible to easily adjust the sensitivity in the detection circuit (not explained). Therefore, it is possible to easily adjust and absorb variations in magnetization.

Further, there is an effect that a differential position sensor using a Hall element can be obtained, which can easily mechanically protect the Hall element.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of the core in the direction of the movable axis, Fig. 2 is a longitudinal cross-sectional view of the core in the direction perpendicular to the movable axis, Fig. 3 is a perspective view showing the shape of the core, and Fig. 4 is a vertical cross-sectional view of the core in the direction of the movable axis. It is a longitudinal cross-sectional view in the direction perpendicular to the movable axis when it moves, and is a diagram showing the flow of magnetic flux.

Claims (1)

[Claims] 1. In a position sensor using a Hall element, consisting of a permanent magnet, a Hall element, a core that controls the direction of magnetic flux flow, and a body that fixes the magnet and Hall element, the magnet and Hall element are fixed to the body, and the measurement is symmetrical. A differential position sensor using a Hall element, characterized in that the direction of magnetic flux passing through the Hall element is changed by a core that moves integrally with the Hall element, and a differential magnetic flux is obtained with one Hall element.