JPH01107111A - Magnetic encoder - Google Patents

Abstract

PURPOSE:To perform fine adjustment, by providing similar position adjusting magnetic resistance elements in parallel to the magnetic resistance elements for a reference signal of a magnetic sensor. CONSTITUTION:Magnetic resistance elements R1-R4 are arranged to an encoder part at a definite interval, and a magnetic resistance element R11 and two parallelly arranged magnetic resistance elements R12, R13 are respectively arranged to a reference signal part in the circumferential and axial directions thereof and terminals 13-19 are connected to the respective resistance elements. When the interval between the elements R12, R13 of parallel arrangement for a reference signal is set to (t), if the terminal 13 is changed over to the terminal 19, the same waveform delayed by the interval (t) is obtained. When many elements of this kind are arranged, further much positional adjustment becomes possible. By this method, fine adjustment can be easily performed by the selection of the elements parallelly arranged at a predetermined interval.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic encoder used for detecting the rotational position and rotational speed of an electric motor or the like.

(Prior Art) A conventional magnetic encoder (hereinafter referred to as an encoder) will be explained with reference to FIGS. 4 to 9.

4 and 5 are a side view showing the encoder in use and a side view showing the internal structure of the encoder, respectively.

In FIG. 4, the rotary shaft 2 protruding from both sides of the electric motor 1 has a load device 3 on the front side, and a rotary shaft 6 of an encoder 5 on the rear side via a screw-fastened coupling 4. connected. The above-mentioned coupling 4 is fixed with two screws 7 and 8 after the rotating shafts 2 and 6 of the electric motor 1 and encoder 5 are inserted from both sides, respectively.

In FIG. 5, the encoder 5 is connected to a case (not shown).
i The above-mentioned rotating shaft 6 is attached so as to pass through the fixed support part 9, the magnetic drum 10 is attached to the case side of this rotating shaft 6, and the outer peripheral surface of this magnetic drum 10 is connected to the rotating shaft 6 through a small gap. It consists of a magnetic sensor 12 fixed to the inside of a support arm 11 implanted in the support part 9 so as to face each other.

On the cylindrical surface of the magnetic drum 10, several to several thousand pulses are generated per rotation. An encoder track 10a on which a continuous signal is recorded, and a reference signal track 10c on which one reference signal section 10b is recorded on one circumference so as to generate a reference signal once per rotation are formed.

FIG. 6 is an enlarged development view of the magnetic drum 10, in which SN poles that generate one pulse are continuously recorded at a pitch of λ on the encoder track 10a, and N poles with a width of 1/2λ on the reference signal track 10c. 1 on the circumference as the reference signal part 10b
Only the locations are recorded. Magnetic sensor 1 facing this
2 includes an encoder section 12 facing the encoder track 10a and the reference signal track 10c, respectively.
a and a reference signal section 12b are provided. The encoder section 12a has four magnetoresistive elements R1t R3, R2= arranged in the axial direction at a pitch of 1/8λ.
It is composed of R4. Further, the reference signal section 12b is
Two magnetoresistive elements R arranged circumferentially and axially
□, and R12.

FIG. 7 is an equivalent circuit diagram of the magnetic sensor 12. When a DC power source is connected between terminals 13 and 14 and between terminals 14 and 15, an encoder signal is obtained from terminals 16 and 17, and a reference signal is obtained from terminal 18. It will be done. Terminal 13 and terminal 1 above
4, there are two magnetoresistive elements R of the reference signal section 12b.
1□ and R13 are connected in series, and the terminal 18 is taken out from the middle. Also, the above terminal 14 and terminal 1
Between 5 and 5, two sets of magnetoresistive elements R1 and R4 and R1 and R3, each two of which are connected in series, are connected in parallel, and terminals 16 and 17 are taken out from the middle of each series connection. There is.

The operation of the encoder configured in this way will be explained. When the magnetic drum 10 rotates in the direction shown by arrow A in FIG. 6, the encoder signal with a continuous waveform is output from the terminals 16 and 17, and the reference signal with an erect waveform is output from the terminal 18, as shown in FIG. can get. When this is processed by an electronic circuit, an encoder signal with a continuous digital waveform and a reference signal with an erect digital waveform as shown in FIG. 9 are obtained.

(Problems to be Solved by the Invention) However, in the above configuration, when attaching the encoder 5 to the rotating shaft 2 of the electric motor 1 directly connected to the load device 3,
The positioning of the load device 3 and the encoder 5 is fixed by tightening the screw 7 of the coupling 4 while maintaining the output signal of the encoder 5 and the position of the load device 3 by 5uxt.
For example, in the encoder 5 with 1000 pulses per rotation, the angle of one pulse is 0.36@, and it is extremely difficult to adjust the angle of one pulse.

In addition, once the screw 7 is tightened, the surface of the rotating shaft 2 is scratched, and even if a minute angle adjustment is made, the screw 7 gets into the scratch and the adjustment cannot be made.The present invention solves the above problem. This problem is solved by providing an encoder that can be finely adjusted.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a magnetoresistive element R0 for position adjustment that is similar to the magnetoresistive element R1□ for the reference signal of the magnetic sensor, and It is intended to provide

(Function) With the above configuration, since the two magnetoresistive elements R12 and R1 are arranged at a predetermined interval, fine adjustment can be easily made depending on which one is selected.

(Example) An example of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a plan view of a magnetic sensor 12 according to the present invention, in which four magnetoresistive elements R, R3, R2, and R4 are arranged at a pitch of 1/8λ in the encoder section, and a circle is arranged in the reference signal section. Magnetoresistive elements Ri are provided in the circumferential direction and the axial direction, respectively.
□ and two parallel magnetoresistive elements R13 and R
are arranged, and terminals 13 to 19 are respectively connected thereto.
is connected. These connection methods are shown in the equivalent circuit diagram of FIG. 2, but the difference from the conventional example is that the terminal 19 connected to the newly added magnetoresistive element R1 is connected to a DC power source. Assuming that the interval between the two parallel magnetoresistive elements R□2 and R for the reference signal is t as shown in FIG. 1, terminal 13 and terminal 19
As shown in FIG. 3, the same waveform delayed by the interval t is obtained.

In this embodiment, two magnetoresistive elements are used for the reference signal, but it goes without saying that by arranging more elements, more positional adjustments can be made.

Further, although this embodiment has been described using a rotary encoder as an example, it can also be used as a linear encoder that detects position and movement on a straight line.

Moreover, the magnetic sensor 12 can be easily manufactured by forming a plurality of magnetoresistive elements on a flat surface of a substrate.

(Effects of the Invention) As described above, according to the present invention, the reference signal position can be easily adjusted by switching the connection terminals while the coupling remains fixed. Moreover, the magnetoresistive elements are located in close proximity.

Since they have similar shapes, there is no need to change the waveform processing circuit, so it can be easily implemented.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a magnetic sensor used in an encoder according to the present invention, and FIG. 2 is an equivalent circuit diagram thereof. FIG. 3 is a waveform diagram of a reference signal obtained by the present invention. Fig. 4 is a side view of the electric device with the encoder attached, Fig. 5 is a side view showing the configuration of the encoder, Fig. 6 is an exploded view of the magnetic drum used in a conventional encoder, and Fig. 7 is a side view of the electric device with the encoder attached.
The figure is an equivalent circuit diagram of the magnetic sensor, FIG. 8 is an output waveform diagram obtained from the encoder, and FIG. 9 is an output waveform diagram after waveform processing. 1... Electric motor, 2, 6...: Rotating shaft, 3... Load device, 4... Coupling, 5... Encoder, 7
, 8... Screw, 9... Support part, 10... Magnetic drum, 10a... Encoder track, 10b...
...Reference signal section, 10c...Reference signal track, 11
...Support arm, 1z...Magnetic sensor, 12a...Encoder section, 12b...Reference signal section, 13.14.
15.16.17°18, 19... terminal, R,, R,
,R3,R,. R,,,R,,,R,,... Magnetoresistive element. 7th Prisoner 13-18 Terminal

Claims (1)

[Claims] A magnetic encoder using a magnetoresistive element as a magnetic sensor, characterized in that a plurality of magnetoresistive elements for detecting a reference position are provided.