JP2002168658A - Absolute value encoder and its design value determining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily assemble an absolute value encoder, having an optical system detection section for single rotation and a magnetic detection section for multiple rotations, and to improve flexibility in design. SOLUTION: A magnetic resistance element for composing a multiple-rotation sensor and a bias magnet are arranged, while they are distributed to the front and the rear of a printed circuit board that is fixed to an encoder case for ease of assembly. At the same time, by adjusting the length of the connection section between the encoder case and the printed circuit board, the responsiveness of the spacer of an optical system is decreased, while at the same time, the dimensions of the optical system are designed optimally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absolute value encoder for detecting an absolute angle of a rotating body, and more particularly, to a case where power is applied to the encoder when a power failure occurs or when a system in which the encoder is mounted is stopped. The present invention relates to an absolute value encoder that can be suitably applied to a sensor for detecting multi-rotation information when an encoder is rotated by external power in a state where no encoder is turned.

[0002]

2. Description of the Related Art As an example of a conventional optical absolute value encoder, there is an apparatus shown in FIG. 1 of JP-A-2000-146626. FIG. 4 shows the upper half surface of the sectional view of the encoder device again.

This known encoder device has an encoder case 1, a hollow shaft 5 (axial center CL) attached to the case 1 via bearings 3 and 4, and a printed board 8 fixed to the case 1. The optical system further includes components of an optical system for detecting an absolute rotation angle within one rotation described below and a magnetic system for detecting a rotation speed and a rotation direction of one or more rotations.

A rotary slit plate 6 having a slit portion 61 for transmitting and blocking light on its outer peripheral portion is attached to the hollow shaft 5. The slit section includes a plurality of slits or a transparent / opaque section having a pitch satisfying a required angular resolution.

[0005] A light emitting diode 2 is provided in the encoder case 1, and the components are arranged such that emitted light of the light emitting diode 2 reaches the light receiving element 7 through the slit portion 61 of the rotary slit plate 6. The light receiving element 7 is mounted on a printed circuit board 8 fixed to the encoder case 1.
It is mounted together with other necessary electronic circuit components 11 to make necessary electric connections.

The above is the configuration of the optical system.
It is mainly composed of a rotating magnet 10 attached to the hollow shaft 5 and a multi-rotation detecting sensor 14 provided on the back side of the light receiving element mounting surface of the printed circuit board 8, between the rotating magnet 10 and the rotating slit plate 6. Has a space plate 13 inserted.

This known absolute value encoder is intended to eliminate the drawbacks of the conventional device in which a spacer is inserted between a light receiving element and a printed circuit board. However, there is a problem that the degree of freedom regarding the height of electronic components separately provided on the printed circuit board cannot be sufficiently secured.

That is, in FIG. 4, when a request to use a high electronic component 11 is required, the adjustment margin must be dealt with only by the magnetic spacer 13. It was difficult to satisfy the performance of both the optical system and the magnetic system.

[0009]

SUMMARY OF THE INVENTION Accordingly, the present invention aims to change the idea and make the dimensional adaptation of the optical system and the magnetic system in the absolute value encoder to the electronic component without depending on the dimensional accuracy of the spacer. It is an object to achieve the required height while permitting it.

[0010] In other words, the present invention starts with a spacer that allows a desired height of an electronic component, and achieves both dimensional optimal values of an optical system and a magnetic system using such a spacer. Is the subject.

[0011]

According to the present invention, according to the present invention, there is provided a hollow shaft mounted on a case via a bearing, and a slit portion mounted on the hollow shaft and transmitting and blocking light at an outer peripheral portion. A rotating slit plate, a light emitting element arranged in an encoder case so as to irradiate a slit portion of the rotating slit plate, a light receiving element arranged at a predetermined distance from the rotating slit plate, An optical detection unit for one rotation composed of an element and a carrier substrate mounted at a position sandwiching the printed circuit board, a rotating magnet mounted on the hollow shaft via the rotating slit plate, and In an optical and magnetic encoder provided with a multi-rotation detection sensor for detecting magnetic field information, the multi-rotation detection sensor includes a magnetoresistive element and a bias magnet. And at least the bias magnet is disposed on the anti-rotating magnet side of the printed circuit board, and the magnetic field intensity applied to the magneto-resistive element by the rotating magnet and the magnetic field intensity applied to the magneto-resistive element by the bias magnet. Is achieved by adjusting the magnetizing strength of each magnet or the distance between the magnetoresistive element and the bias magnet so that the ratio is equal or a certain ratio (the invention of claim 1).

The slit portion of the rotary slit plate in the present invention is not necessarily required to be a space, but may be any as long as the slit can be substantially constituted by the transparent portion and the opaque portion.

[0013]

The above object is achieved in a simple manner by using the printed circuit board itself as the spacer constituting the multi-rotation detection sensor in the invention described in claim 1 (the invention of claim 2). ).

Although the thickness of the printed circuit board cannot be changed freely as in the case of a normal spacer, there is no problem because the optimum adjustment of the magnetic system can be adjusted by changing the magnetic field strength of the bias magnet.

Further, the above object can be attained by arranging the magnetoresistive element, the bias magnet and the spacer constituting the multi-rotation detecting sensor all on the side opposite to the rotating magnet of the printed circuit board. (The invention of claim 3).

The above object is also advantageously achieved by providing the rotating magnet on the end face of the hollow shaft and on the hollow shaft side of the rotating slit plate in the invention according to any one of the first to third aspects of the present invention. The invention of claim 4).

According to another feature of the present invention, a hollow shaft mounted on the case via a bearing, a rotary slit plate mounted on the hollow shaft and having a slit on its outer periphery for transmitting and blocking light, A light emitting element disposed in the encoder case so as to irradiate the slit portion of the rotary slit plate, a light receiving element disposed at a position separated from the rotary slit plate by a predetermined distance, and the light receiving element and the printed board are sandwiched. An optical detection unit for one rotation composed of a carrier substrate mounted at a position, a rotating magnet mounted on the hollow shaft via the rotating slit plate, and magnetic field information provided on the printed circuit board An optical and magnetic encoder comprising a multi-rotation detection sensor comprising a magnetoresistive element, a bias magnet and a spacer for performing Is determined to be higher than the maximum required height of the electronic components installed on the printed circuit board, and then the length of the connecting part that fixes the printed circuit board to the hollow shaft is determined by the mutual position of the light emitting element, light receiving element, and rotating slit plate. Is achieved by a design value determination method that determines the length to optimize the value (the invention of claim 5).

[0018]

FIG. 1 shows an optimum embodiment of the present invention. Prior to describing this embodiment, the embodiment of FIGS. 2 and 3 will be described.

2 and 3, the same reference numerals as those in FIG. 4 denote the same or equivalent components. The newly added components are a carrier substrate 9 inserted between the light receiving element 7 and the printed circuit board 8 and a magnetoresistive element 2 provided on the anti-rotation magnet side of the printed circuit board 8.
1, a multi-rotation detection sensor 20 including a spacer 22 and a bias magnet 23. Reference numeral 12 denotes an electronic component.

The difference between the embodiment of FIG. 2 and the embodiment of FIG.
The only difference is whether the rotating magnet 10 is on the hollow shaft side of the rotating slit plate 6 or on the printed circuit board 8 side.

The thickness of the carrier substrate 9 is not determined for adjusting the dimensions of the optical system, but is determined solely for absorbing the maximum height of the electronic component 11. Size adjustment of the optical system, that is, the light emitting element 2, the light receiving element 7, and the rotating slit plate 6
Is adjusted by adjusting the length of the connecting portion 15 for fixing the printed circuit board 8 to the hollow shaft 5.

The multi-rotation is detected by detecting the rotation of the magnetic field generated by the rotation of the rotary magnet 10 attached to the hollow shaft 5 by the multi-rotation detection sensor 20.

In this case, in order for the multi-rotation detecting sensor to correctly detect a change in the magnetic field, the magnetic field strength of the rotating magnet 10 is B1, the magnetic field strength of the bias magnet 23 is B2, and the rotating magnet 1 is
When the distance from 0 to the magnetoresistive element 21 is D1, and the distance from the bias magnet 23 to the magnetoresistive element 21 (that is, the thickness of the spacer 22) is D2, the following conditions must be satisfied.

B1 × D1 = B2 × D2 1)

In the encoder shown in FIG. 2, in order to satisfy Equation 1, first, the interval between the rotary slit plate 6 and the light receiving element 7, which is a major factor in determining the accuracy of one rotation angle detection of the encoder, is determined to an optimum value. Then, the D1 value is determined. Then, the magnetic field strengths B1 and B2 and the thickness D2 of the spacer 22 are optimally designed so that Expression 1 is satisfied.

When manufacturing the multi-rotation detecting sensor 20, the simplest method is to use a double-sided tape having an adhesive effect between the bias magnet 23 and the magnetoresistive element 21 as the spacer 22 between them. .

However, such a structure causes the following problems. That is, in the structure of the multi-rotation detection sensor 20 shown in FIG. 2 or FIG. 3, since the magnet must be mounted after the double-sided tape is stuck on the bias magnet 23, it is difficult to automatically mount the bias magnet. It is. Also, because the shape of these parts is very small,
Assembling work efficiency is deteriorated, and manufacturing costs are increased.

Further, in the structure of the multi-rotation detecting sensor 20 described above, it is necessary to dispose the magnetoresistive element 21 on the surface opposite to the mounting surface of the light receiving element 7, and the magnetoresistive element 21 and the rotating magnet 10
Is very large. Generally, rotating magnet 1
The magnetic field intensity exerted on the magnetoresistive element 21 by 0 is inversely proportional to the square of the distance Dl between the magnetoresistive element 21 and the rotating magnet 10.

For this reason, when D1 increases, the magnetic field strength B1 of the rotating magnet 10 must be increased in order for the rotating magnet 10 to generate a predetermined magnetic field strength in the magnetoresistive element 21. As a result, there is a problem that the cost of the rotating magnet 10 is increased.

Therefore, according to the most preferred embodiment of the present invention,
As shown in FIG. 1, the magnetoresistive element 21 and the bias magnet 23 constituting the multi-rotation detection sensor 20 are assembled in such a manner that the printed circuit board 8 is sandwiched therebetween.

With this structure, unlike the embodiment shown in FIGS. 2 and 3, it is not necessary to insert the spacer 22 between the magnetoresistive element 21 and the bias magnet 23. In other words, by adopting the structure as shown in FIG. 1, it is possible to substitute the printed circuit board 8 for the spacer for securing the interval D2 between the bias magnet 23 and the magnetoresistive element 21.

This eliminates the need for the double-sided tape serving as the spacer 22 disposed between the bias magnet 23 and the magnetoresistive element 21.

The magnetoresistive element 21 and the bias magnet 2
3 can be shortened, the magnetic field strength of the bias magnet 23 can be reduced, and the cost of the bias magnet 23 can be reduced.

Further, by mounting the magnetoresistive element 21 on the light receiving element mounting surface, the rotating magnet 10 and the magnetoresistive element 2 are mounted.
1 can be reduced, and the magnetic field strength of the rotating magnet 10 can be reduced.

[0035]

As described above, according to the present invention, (1) the spacer to be inserted between the light receiving element and the printed board has a height capable of absorbing the maximum height of the electronic component on the printed board, and The optimal position of the mutual spacing between the element, light receiving element and rotating slit plate is ensured by adjusting the length of the connection between the hollow shaft and the printed board, so that the degree of freedom in designing the dimensional adjustment of the optical system is greatly improved. Is obtained.

(2) Bias magnet and magnetoresistive element 21 of a multi-rotation detection sensor used for multi-rotation detection of encoder
By adopting a structure capable of removing the spacer disposed between them, it is possible to reduce the manufacturing cost of the multi-rotation detection sensor unit and the unit cost of the rotating magnet, thereby providing an inexpensive encoder. And the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an optimal embodiment of the present invention.

FIG. 2 is a cross-sectional view of another embodiment of the present invention.

FIG. 3 is a sectional view of another embodiment of the present invention.

FIG. 4 is a sectional view of an embodiment of the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Encoder case 2 Light emitting element 5 Hollow shaft CL Center line of each component including hollow shaft 6 Rotating slit plate 7 Light receiving element 8 Printed circuit board 9 Carrier substrate 10 Rotating magnet 11, 12 Electronic components 12 Driver 15 Connecting part 20 Multi-rotation Sensor 21 Magnetic resistance element 22 Spacer 23 Bias magnet

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yasumitsu Nagasaka 1-1-1, Tanabe-Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in Fuji Electric Co., Ltd. (Reference) 2F077 AA24 AA30 AA44 NN03 NN17 NN30 PP14 PP19 VV02 VV10 VV21 VV31 2F103 CA02 DA01 DA13 EA02 EA12 EB01 EB11 EB33 GA01

Claims (5)

[Claims] 1. A hollow shaft attached to a case via a bearing, a rotary slit plate mounted on the hollow shaft and having a slit portion for transmitting and blocking light on an outer peripheral portion, and a slit portion of the rotary slit plate. A light emitting element arranged in the encoder case so as to be able to irradiate, a light receiving element arranged at a predetermined distance from the rotary slit plate, and a carrier substrate mounted at a position sandwiching the light receiving element and the printed board. An optical detection unit for one rotation, comprising: a rotation magnet attached to the hollow shaft via the rotation slit plate; and a multi-rotation detection sensor provided on the printed circuit board for detecting magnetic field information. In the optical and magnetic encoder provided with, the multi-rotation detection sensor comprises a magnetoresistive element, a bias magnet, and a spacer, and at least The ias magnet is disposed on the anti-rotating magnet side of the printed circuit board, and the magnetic field strength given to the magnetoresistive element by the rotating magnet and the magnetic field strength given to the magnetoresistive element by the bias magnet are equal or a certain ratio. An absolute value encoder characterized in that the magnetizing strength of each magnet or the distance between the magnetoresistive element and the bias magnet is adjusted so as to be as follows. 2. The absolute value encoder according to claim 1, wherein the spacer constituting the multi-rotation detection sensor is a printed circuit board itself. 3. The absolute value encoder according to claim 1, wherein the magneto-resistive element, the bias magnet, and the spacer constituting the multi-rotation detection sensor are all disposed on the anti-rotation magnet side of the printed circuit board. . 4. The absolute value encoder according to claim 1, wherein the rotary magnet is provided on the end face of the hollow shaft and on the hollow shaft side of the rotary slit plate. 5. A hollow shaft attached to a case via a bearing, and a light transmitting and transmitting light to an outer peripheral portion attached to the hollow shaft.
A rotating slit plate having a slit portion for shielding light, a light emitting element arranged in an encoder case so as to irradiate the slit portion of the rotating slit plate, and a light receiving device arranged at a position separated by a predetermined distance from the rotating slit plate An element, an optical detection unit for one rotation composed of a light receiving element and a carrier substrate mounted at a position sandwiching the printed circuit board, and a rotating magnet attached to the hollow shaft via the rotating slit plate. An optical and magnetic encoder provided with a multi-rotation detection sensor provided on the printed circuit board for detecting magnetic field information, a magnetoresistive element, a bias magnet, and a spacer, wherein the height of the carrier substrate is Determined to be higher than the maximum required height of the electronic components to be installed, and then the length of the connecting part that fixes the printed circuit board to the hollow shaft, A design value determining method for an absolute encoder, wherein a mutual position of a light emitting element, a light receiving element, and a rotary slit plate is determined to have a length that optimizes the mutual position.