JPH06317430A - Rotation detector - Google Patents

Abstract

PURPOSE:To enable a rotation detector to detect the rotating speed and rotating direction of a rotating body and, at the same time, to reduce the size of the detector by arranging a plurality of Hall elements in the rotating direction of the rotating body in a detecting section and installing a magnet to the surface of the detecting section opposite to the surface of the section counterposed to the rotating body. CONSTITUTION:A detecting section 2 is positioned so that the section can be counterposed to the side face section of a gear 1. The section 2 has Hall elements 3, 4, and 5 arranged in the rotating direction of the gear 1 and a magnet 6 on its rear surface side. The distances between the elements 3-5 and the tip of the gear 1 is about 1-3mm. When the elements 3-5 are arranged in such a way, the gear 1 can be detected even when no multipole-magnetized magnet is used, since the elements 3-5 detect the density of magnetic flux formed between the gear 1 and magnet 6. In addition, the magnetic flux changes in such a way that the magnetism is not inverted as in the case of multipole magnetization, but the flux changes in one direction depending upon the distances between the gear 1 and elements 3-5. Moreover, since the elements 3-5 are continuously arranged, the rotating direction of the gear 1 can be detected from the detecting timing of the elements.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device for an object, and more particularly to a detecting device for detecting the rotational speed of a gear made of a magnetic material such as iron.

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 5 is a schematic view for explaining a rotation detecting device according to a conventional example, (a) is a top view of a multi-pole magnetized magnet for detecting a rotation state, and (b) is a similar multi-pole magnetized magnet. FIG. 6 is a side view, and FIG. 6 is a circuit diagram of the circuit used in FIG.

A conventional rotation detecting device, as shown in FIG.
A single Hall element 21 is provided on the front surface of the circular multi-pole magnetized magnet 20.
Had been placed. The multi-pole magnetized magnet 20 is installed in a gear or the like (not shown) so as to be arranged, for example, in the center of the gear so as to be synchronized with the gear. Alternatively, it may be arranged so as to divide the rotation of the gear.

In this structure, the multi-pole magnetized magnet 20 also rotates at the same time as the rotation of the gear, and the change in magnetic flux accompanying this is read by the hall element 21 to detect the number of rotations.

The circuit of this device has a structure as shown in FIG. 6, for example. In FIG. 6, 22 is a comparator, 23 is an output transistor, 24 is a power supply line, and 25 is a resistor.

[0006]

By the way, the above-mentioned conventional method requires a large space because of the use of a multi-pole magnetized magnet, and is costly. Further, conventionally, one Hall element is generally used to detect the number of rotations, and it is not possible to detect a change amount such as a rotation direction, a linear movement amount, or a movement direction. Further, as the rotating body, a special material such as multi-pole magnetization is required, and the amount of change in the position of a general magnetic body such as iron cannot be detected.

Therefore, an object of the present invention is to provide a detecting device which can detect the number of rotations and the direction of rotation of a rotating body made of a general magnetic body and can be downsized.

[0008]

In order to achieve the above object, the present invention is directed to a rotating body made of a magnetic material, in which steps are regularly formed on the side surface, and to face the side surface of the rotating body. The detection unit includes a plurality of Hall elements arranged in a rotation direction of the rotating body, and a magnet is provided on a surface opposite to a surface facing the rotating body. It is characterized by

[0009]

Since the Hall element detects the magnetic flux density of the magnetic flux formed between the gear and the magnet, the gear itself can detect the rotation even if the gear itself is not a multi-pole magnetized magnet. Further, unlike the conventional case, a plurality of Hall elements are arranged continuously instead of a single element, so that the rotation direction of the gear can be detected from the detection timing of each of these elements.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 is a schematic diagram of a rotation detecting device according to an embodiment of the present invention, FIG. 2 is a circuit diagram thereof, and FIG. 3 is a timing chart thereof. It should be noted that the same functional parts as those in the conventional example of FIG.

As shown in FIG. 1, the rotation detecting device of this embodiment is provided with a detecting portion 2 so as to face a side surface portion of a gear 1 made of a general magnetic material such as iron. This detector 2
Is three consecutive Hall elements 3, 3 in the direction of rotation of the gear.
4 and 5, and the magnet 6 is arranged on the back side thereof. The distance between the Hall elements 3, 4, 5 and the tip of the gear 1 is about 1 to 3 mm.

Gear 1, hall elements 3, 4, 5 and magnet 6
With the above arrangement, since the Hall element detects the magnetic flux density of the magnetic flux formed between the gear 1 and the magnet 6, the gear 1 itself does not have to be a multi-pole magnetized magnet as in the conventional case. It becomes possible to detect. Note that the magnetic flux change here is different from that of the conventional multi-pole magnetized magnet, and the magnetism is not inverted, and changes in one direction depending on the distance between the gear 1 and the Hall elements 3, 4, and 5. .

Further, unlike the conventional case, a plurality of Hall elements are arranged continuously instead of a single element, so that the rotation direction of the gear 1 can be detected from the detection timing of each of these elements.

A detailed description will be given below with reference to the circuit diagram of FIG. 2 and the timing chart of FIG.

In the circuit of this embodiment, as shown in FIG. 2, the output voltage on one side of the hall element 4 located at the center is compared with the output voltage on one side of the hall elements 3 and 5 located at both ends and the comparator 7, respectively. 8 and the comparators 7, 8
Is taken out through the transistors 9 and 10. The outputs of the comparators 7 and 8 are input to the D flip-flop 11 so that the rotation direction of the gear 1 can be detected. Reference numerals 12 and 13 are resistors.

In this circuit configuration, taking the case where the gear 1 rotates in the direction A as an example, the output voltages of the Hall elements 3, 4 and 5 of the above circuit change as shown in FIG. 3 (a). . On the other hand, since the outputs of the comparators 7 and 8 are inverted at the time point when the output voltages of the two Hall elements become the same, they change as shown in FIGS. 3B and 3C, respectively. On the other hand, D flip-flop 1
The output of 1 becomes the HIGH level as shown in FIG.
Therefore, the rotational speed can be determined from FIGS. 3B and 3C, and the rotational direction can be determined from FIG. 3D.

When the gear 1 rotates in the direction opposite to A, the outputs of the comparators 7 and 8 are shown in FIGS. 3 (c) and 3 (b), respectively.
Corresponding to. The output of the D flip-flop 11 is L
It becomes the OW level.

FIG. 4 is a circuit diagram of a rotation detecting device according to another embodiment of the present invention. The difference from the circuit diagram of FIG. 2 is that differential amplifiers 14 and 15 are inserted in front of the comparators 7 and 8. This is a configuration corresponding to the case where the output voltages of the Hall elements 3, 4, 5 are too small and the comparators 7, 8 do not operate.

As described above, according to the present embodiment, the rotating operation can be detected even with respect to the rotating body made of a general magnetic material such as iron, which is not a multi-pole magnetized magnet as in the conventional case. The configuration can be simplified, the size can be reduced, and the cost can be reduced. Further, it is possible to detect the rotation direction of the gear, which cannot be detected conventionally.

In the above embodiment, an example in which three Hall elements are used has been shown, but it goes without saying that the number of Hall elements is not limited to this as long as the number can detect the rotation direction. Further, by incorporating the Hall elements 3, 4, 5 and the above circuit in the same package, the device can be made compact. The magnet 6 may be incorporated in the same package.

[0021]

As described above, according to the present invention,
The rotating operation of a rotating body made of a general magnetic material such as iron can be detected, so that the structure of the detecting device can be simplified, downsizing and cost reduction can be achieved. Further, it is possible to detect the rotation direction of the gear, which cannot be detected conventionally.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a rotation detection device according to an embodiment of the present invention.

2 is a circuit diagram of the device of FIG.

3A to 3D are timing charts of respective parts of the circuit of FIG.

FIG. 4 is a circuit diagram of a rotation detecting device according to another embodiment of the present invention.

5A and 5B are respectively a top view and a side view of a multi-pole magnetized magnet for detecting a rotation state of a rotation detection device according to a conventional example.

6 is a circuit diagram of a circuit used in the device of FIG.

[Explanation of symbols]

 1 Rotating body 2 Detecting unit 3, 4, 5 Hall element 6 Magnet

Claims (1)

[Claims] 1. A rotating body made of a magnetic material having side surfaces regularly formed with steps, and a detecting section arranged so as to face the side surface of the rotating body, wherein the detecting section is the rotating body. A plurality of Hall elements arranged in the direction of rotation, and a magnet provided on the surface opposite to the surface facing the rotating body.