JPH09218052A - Magnetic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a miniaturization while detecting the movement of a subject accurately even when change in a magnetic flux is limited accompanying the movement of the subject. SOLUTION: A magnetic sensor chip 14 is connected being molded to leads 15-18 inside a magnetic sensor 11 provided between a gear 12 and a magnet 13. A first magnetic lens lead 20 and a second magnetic lens lead 21 are made up of a lead frame in the magnetic sensor 11 to form the leads 15-18 while being integrated with the magnetic sensor chip 14 by a resin molding. The interval of the tip parts 20b and 21b of the lens leads is set 3/2 times as much as 1 pitch m of the gear 12. As the gear 12 turns, a difference is generated in the quantity of a magnetic flux between a magnetic flux passing through the first magnetic lens lead 20 and a magnetic flux passing through the second magnetic lens lead 21 and the magnetic flux passing through the magnetic sensor chip 14 varies in direction. Thus, the detection of the rotation of the gear 12 is possible by checking changes in the direction of the magnetic flux.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor for detecting a movement of an object to be detected by detecting a change in magnetic flux interlinking the object to be detected.

[0002]

Conventionally, a magnetic sensor including a magnetic sensor chip such as a Hall element or a magnetoresistive element (hereinafter abbreviated as MRE) detects the rotation of a gear as an object to be detected. This is done, and an example thereof is shown in FIG.

In FIG. 6, the magnetic sensor 1 is, for example, M
It has a built-in magnetic sensor chip 2 composed of RE, and is provided between a gear 3 made of a magnetic material as an object to be detected and a magnet 4 for radiating a magnetic field to the gear 3. In this case, the outer peripheral portion of the gear 3 has a ridge 3 at a predetermined pitch
a and valley portions 3b are continuously and alternately formed, and the above-described magnetic sensor chip 2 faces the movement loci of the mountain portions 3a and valley portions 3b.

According to this, a part of the magnetic flux radiated from the N pole 4a of the magnet 4 passes through the magnetic sensor chip 2 in the magnetic sensor 1, and further, the gear 3 is linked to the S pole 4b.
Leads to. At this time, since the gear 3 is formed of a magnetic material, in the magnetic flux that links the gear 3, the portion of the gear 3 that is close to the N pole 4a (that is, the mountain portion 3 of the gear 3).
The magnetic flux interlinking with a) is larger than the magnetic flux interlinking with the portion far from the N pole 4a (that is, the valley 3b of the gear 3), and as a result, the magnetic flux passing through the magnetic sensor chip 2 is As a whole, the gear 3 inclines toward the crest 3a (indicated by arrow P in FIG. 6).

Therefore, when the gear 3 rotates, the peak portion 3
Since the a and the valley portions 3b are continuously and alternately opposed to the magnetic sensor chip 2, the direction of the magnetic flux passing through the magnetic sensor chip 2 is changed according to the rotation, and the direction of the magnetic flux is changed. By detecting the change, the gear 3
It becomes possible to detect the rotation.

However, in the above-mentioned structure, when the distance between the magnetic sensor chip 2 and the gear 3 is large,
The change in the direction of the magnetic flux passing through the magnetic sensor chip 2 caused by the rotation of the gear 3 is reduced, and as a result, the accuracy of detecting the change in the magnetic flux direction in the magnetic sensor chip 2 is lowered, and the change in the magnetic flux direction is detected. It may not be possible.

Further, as shown in FIG. 7, even when the pitch between the crests 5a formed on the gear 5 is extremely small with respect to the magnetic sensor chip 2, the change in the direction of the magnetic flux passing through the magnetic sensor chip 2 is changed. Becomes smaller, and the same problem as described above occurs.

Therefore, even if the distance between the magnetic sensor chip 2 and the gear 3 is large, or if the pitch between the crests 5a of the gear 5 is extremely small with respect to the magnetic sensor chip 2, the magnetic sensor chip 2 is In order to improve the detection accuracy of the change in the direction of the passing magnetic flux, a configuration as shown in FIG. 8 is considered.

In this structure, magnetic lenses 6 and 7 made of a magnetic material having a high magnetic permeability are arranged between the gear 5 and the magnetic sensor chip 2. These magnetic lenses 6 and 7 are along the magnetic flux direction, and the tips of their gears 5 side are set at an interval different from the pitch between the crests 5a of the gears 5 (in FIG. 8, gear 5). Mountain part 5a
The interval is set to 3/2 times the pitch).

According to this, the magnetic lenses 6 and 7
Is formed of a magnetic material having high magnetic permeability,
The magnetic flux passing through the magnetic sensor chip 2 concentrates through the magnetic lenses 6 and 7. In this case, as shown in FIG. 8, when one magnetic lens 6 faces the mountain portion 5a of the gear 5, the other magnetic lens 7 faces the valley portion 5b of the gear 5, Magnetic lens 6
When there is a large amount of magnetic flux passing through, the magnetic flux passing through the other magnetic lens 7 becomes relatively small.

Therefore, when the gear 5 rotates, the magnetic flux amount passing through the magnetic lens 6 and the magnetic flux passing through the magnetic lens 7 have a somewhat different relationship between the magnetic flux amount and the magnetic sensor chip. The magnetic flux passing through 2 changes greatly when viewed as a whole, so that the rotation of the gear 5 can be reliably detected.

However, in the above-mentioned structure, since the magnetic lenses 6 and 7 are provided separately from the magnetic sensor chip 2, there are some restrictions on miniaturization of the magnetic lenses 6 and 7 with respect to the magnetic sensor chip 2. There is. That is, when the magnetic sensor chip 2 is small, the magnetic lens 6
And 7 cannot be accurately arranged with respect to the magnetic sensor chip 2 and the pitch between the crests 5a of the gear 5 is narrow, the magnetic lenses 6 and 7 and the crest 5a of the gear 5 can be accurately measured. Cannot be placed. As a result, the change in direction of the magnetic flux passing through the magnetic sensor chip 2 becomes ambiguous,
There is a drawback that the rotation of the gear 5 cannot be detected accurately.

The present invention has been made in view of the above circumstances. An object of the present invention is to detect the movement of an object to be detected in a structure for detecting the movement of the object to be detected based on a change in magnetic flux interlinking with the object to be detected. An object of the present invention is to provide a magnetic sensor that can detect the movement of an object to be detected with high accuracy even when the change in the magnetic flux accompanying the change is small and can be downsized.

[0014]

The magnetic sensor of the present invention comprises:
By being arranged so as to oppose the movement locus of the convex portions of the predetermined pitch formed on the magnetic substance to be detected, by detecting the change in the magnetic flux of the detection magnetic flux interlinking with the detected substance from the magnetic flux generating means, In the magnetic sensor for detecting the movement of the object to be detected, a magnetic sensor IC having a built-in magnetic sensor chip for detecting a magnetic flux change of the magnetic flux for detection, the magnetic sensor chip in the magnetic sensor IC, and the object to be detected. And at least two magnetic flux concentrating portions for concentrating the magnetic flux for detection on the magnetic sensor chip, the magnetic flux being concentrated on the magnetic sensor chip. The magnetic flux concentration section is formed of a lead frame for manufacturing the magnetic sensor IC, and a predetermined dimension between the magnetic flux concentration section and another adjacent magnetic flux concentration section has a convex portion of the detected object. Characterized in place of being set to the different dimensions pitch.

According to the magnetic sensor having the above structure, a large amount of the detection magnetic flux interlinking the magnetic flux generating means with the object to be detected passes through the magnetic flux concentrated portion facing the convex portion of the object to be detected. At this time, when the convex portion moves according to the movement of the object to be detected and faces the other magnetic flux concentration portion, the detection magnetic flux is interlinked with the other magnetic flux concentration portion. Therefore, it is possible to detect the movement of the object to be detected by detecting the change in the magnetic flux that occurs between these different magnetic flux concentration portions in the magnetic sensor chip.

In this case, the magnetic flux concentration section is a magnetic sensor IC.
Since it is formed from the lead frame for manufacturing the magnetic sensor IC, it is possible to form the magnetic flux passage portion which is precisely aligned with the magnetic sensor chip in the process of manufacturing the magnetic sensor IC, and to downsize the magnetic sensor. Therefore, it is possible to detect the movement of the convex portion having a narrow pitch, which has been difficult to detect in the past.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which a magnetic sensor of the present invention is applied to rotation detection of a gear will be described below with reference to FIGS.
This will be described with reference to FIG. The magnetic sensor 11 is provided between the rotatable gear 12 as an object to be detected and the magnet 13 as a magnetic flux generating means, with a predetermined space therebetween. The gear 12 is made of a magnetic material, and convex portions 12a and valleys 12b, which are convex portions, are continuously and alternately formed on the outer peripheral portion thereof at a predetermined pitch.

The magnetic sensor 11 is provided with a magnetic sensor chip 14 composed of a 4-terminal magnetoresistive element, as shown in FIG.
4 is connected to an external circuit (not shown) through the leads 15 to 18 by connecting the four terminals to the leads 15 to 18 each made of an IC connecting lead frame. The flat portion 18 is provided on the lead 18 among these.
a is formed, and the magnetic sensor chip 14 described above is mounted on the flat portion 18a. The above magnetic sensor 14
The magnetic sensor IC 19 is basically constituted by the leads 15 to 18.

In the magnetic sensor IC 19, a portion between the magnetic sensor chip 14 and the gear 12 is provided with a first magnetic lens lead 20 and a second magnetic lens lead 21 which are magnetic flux concentrated portions. The first magnetic lens lead 20 and the second magnetic lens lead 21.
Is composed of the same lead frame for IC connection as the leads 15 to 18 described above.
8 is molded at the same time.

The base ends 20a and 21a of the first magnetic lens lead 20 and the second magnetic lens lead 21 on the side of the magnetic sensor chip 14 face both sides of the magnetic sensor chip 14 and the gears. It is provided along the moving direction of the twelve peaks 12a.

On the other hand, the tip portions 20b and 21b of the first magnetic lens lead 20 and the second magnetic lens lead 21 on the gear 12 side are spaced apart from each other, and the pitch between the peaks 12a of the gear 12 is m ( (See FIG. 1), mx
It is set to (2n-1) / 2 (n is a natural number) (in FIG. 1, the case of n = 2 is shown). Thereby, for example, when the tip portion 20b of the first magnetic lens lead 20 faces the crest portion 12a of the gear 12, the tip portion 21b of the second magnetic lens lead 21 faces the trough portion 12b of the gear 12. It is like this.

Further, a third magnetic lens lead 22 which is a sub magnetic flux concentration portion is provided at a portion between the magnetic sensor chip 14 and the magnet 13 in the magnetic sensor IC 19. The base end portion 22a of the third magnetic lens lead 22 on the magnetic sensor chip 14 side faces the magnetic sensor chip 14, and the tip portion 22b on the magnet 13 side faces the N pole 13a of the magnet 13. There is. As a result, the magnetic flux radiated from the magnet 13 is applied to the third magnetic lens lead 2
It passes through the magnetic sensor chip 14 in a state of being focused by 2.

Then, the magnetic sensor chip 14, the leads 15 to 18 and the first to third magnetic lens leads 20.
After resin molding of Nos. 22 to 22, further, as shown in FIG. 3, the magnetic sensor 11 is constructed by bending the portions of the leads 15 to 18 projecting from those moldings. .

Next, the operation of the above structure will be described with reference to FIGS. The magnetic flux emitted from the N pole 13a of the magnet 13 passes through the magnetic sensor chip 14 in a state of being focused by the third magnetic lens lead 22, and then the first magnetic lens lead 20 and the second magnetic lens lead 22. 21 and further links with the gear 12 to reach the S pole 13b of the magnet 13.

At this time, as described above, one of the tip portion 20b of the first magnetic lens lead 20 and the tip portion 21b of the second magnetic lens lead 21 is the mountain portion 13 of the gear 13.
When the magnetic flux passes through the first magnetic lens lead 20 and the magnetic flux that passes through the second magnetic lens lead 21, the other is set so as to face the valley 13b. , There is a difference in the amount of magnetic flux passing through.

That is, as shown in FIG. 4, for example, the first magnetic lens lead 20 has the peak portion 13a of the gear 13 (see FIG.
2nd magnetic lens lead 2
When 1 is opposed to the valley 13b (indicated by x in the figure), a large amount of magnetic flux passes through the first magnetic lens lead 20 and a small amount of magnetic flux passes through the second magnetic lens lead 21. . Therefore, as a whole, the magnetic flux passing through the magnetic sensor chip 14 is inclined toward the first magnetic lens lead 20 side (indicated by arrow Q in the figure).

In this state, the gear 12 moves in the direction of arrow A by m /
When rotated by a movement amount of 2, the first magnetic lens lead 2
The peak portion 13a (shown by v in the figure) is displaced from 0, the valley portion 13b (shown by w in the figure) is opposed, and the valley portion 13b is formed on the second magnetic lens lead 21. (In the figure, x
Is shifted from each other, and the ridges 13a (indicated by y in the figure) come to face each other, resulting in a state as shown in FIG. Therefore, at this time, the first magnetic lens lead 2
The magnetic flux passing through 0 is small and the second magnetic lens lead 2
The magnetic flux passing through 1 increases, and the magnetic flux passing through the magnetic sensor chip 14 tilts toward the second magnetic lens lead 21 side as a whole (indicated by arrow R in FIG. 5).

Hereinafter, as the gear 12 continuously rotates, there is some relation to the amount of magnetic flux passing between the first magnetic lens lead 20 and the second magnetic lens lead 21 as described above. Therefore, the rotation of the gear 12 can be detected by detecting the change in the direction of the magnetic flux corresponding to the change in the magnetic sensor chip 14.

As described above, according to this embodiment, the first magnetic lens lead 20 and the second magnetic lens lead 21 are
The magnetic sensor 1 is formed from an IC connecting lead frame for manufacturing the leads 15 to 18 of the magnetic sensor IC 19.
Since the magnetic sensor chip 14 is formed integrally with the magnetic sensor chip 14 by resin molding in the process of manufacturing 1, the precise alignment can be performed with respect to the magnetic sensor chip 14, whereby the peak 12a of the gear 12 is formed. Even if the change in the direction of the magnetic flux due to the rotation of the gear 12 is small, the rotation of the gear 12 can be accurately detected and the size of the gear 12 can be reduced.

Since the third magnetic lens lead 22 is formed from the IC connecting lead frame in the process of manufacturing the magnetic sensor IC 19 and is also provided by resin molding, the third magnetic lens lead 22 is precise with respect to the magnetic sensor chip 14. The magnetic sensor chip 14 can effectively be focused on the magnetic flux emitted from the magnet 13 while being miniaturized.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. A Hall element may be used for the magnetic sensor chip 14. The first to third magnetic lens leads 20 to 22 may also be used as leads for connecting to an external circuit. The object to be detected may be one that moves in parallel.

[0032]

As is apparent from the above description, according to the first aspect of the invention, the magnetic flux concentration portion for concentrating the magnetic flux on the magnetic sensor chip is provided between the adjacent magnetic flux concentration portion. Since the predetermined size is set to a size different from the pitch between the convex parts of the object to be detected and the magnetic sensor IC is formed from the lead frame, the magnetic flux concentration part is integrated with the magnetic sensor chip to the magnetic sensor chip. Therefore, even if the change in the magnetic flux due to the movement of the detected object is small, the movement of the detected object can be detected accurately and the size can be reduced. You can

According to the second aspect of the present invention, since the magnetic sensor IC is formed of the lead frame and provided with the sub-magnetic flux concentrating portion for concentrating the magnetic flux, the magnetic sensor IC can be downsized and the magnetic flux can be reduced. The magnetic flux emitted from the generating means can be effectively focused on the magnetic sensor chip.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view of a magnetic sensor.

FIG. 3 is a side view of the magnetic sensor.

FIG. 4 is a diagram showing a state in which the magnetic flux is inclined toward the first magnetic lens lead side.

FIG. 5 is a diagram showing a state in which the magnetic flux is inclined toward the second magnetic lens lead side.

FIG. 6 is a diagram corresponding to FIG. 1 showing a conventional example.

FIG. 7 is a view corresponding to FIG. 1 showing a different conventional example.

FIG. 8 is a view corresponding to FIG. 1 showing a further different conventional example.

[Explanation of symbols]

In the drawing, 11 is a magnetic sensor, 13 is a magnet (magnetic flux generating means), 14 is a magnetic sensor chip, and 19 is a magnetic sensor I.
C and 20 are the first magnetic lens lead (magnetic flux concentration part), 2
Reference numeral 1 is a second magnetic lens lead (magnetic flux concentrating portion), and 22 is a third magnetic lens lead (sub magnetic flux concentrating portion).

Claims (2)

[Claims] 1. A magnetic flux change of a magnetic flux for detection, which is arranged so as to face a movement locus of convex portions formed on a magnetic substance to be detected and having a predetermined pitch, and which interlinks the magnetic flux generating means with the substance to be detected. In the magnetic sensor for detecting the movement of the object to be detected by detecting, a magnetic sensor IC having a built-in magnetic sensor chip for detecting a magnetic flux change of the detection magnetic flux, and the magnetic sensor in the magnetic sensor IC. At least two magnetic fluxes, which are provided between the chip and the object to be detected and are separated from each other by a predetermined dimension along the moving direction of the convex portion of the object to be detected, to concentrate the magnetic flux for detection on the magnetic sensor chip. The magnetic flux concentration portion is formed of a lead frame for manufacturing the magnetic sensor IC, and has a predetermined dimension between the magnetic flux concentration portion and another adjacent magnetic flux concentration portion. A magnetic sensor having a size different from a pitch between convex portions of an object to be detected. 2. The magnetic sensor IC includes a sub-magnetic flux concentrating portion, which is formed from the lead frame and concentrates the magnetic flux for detection from a side opposite to the magnetic flux concentrating portion, in the magnetic sensor chip. The magnetic sensor according to claim 1, wherein: