JPS63148116A - Rotary encoder - Google Patents

Abstract

PURPOSE:To obtain plural kinds of output signals by a single magnetic drum by providing a magnetic sensor which detects the arrival of a magnetized part and an irregularly magnetized part formed at the periphery of a rotary body and plural comparators which input the outputs of the magnetic sensor. CONSTITUTION:The magnetized part 1a where N and S poles are magnetized alternately is formed on the magnetic drum 1 in its circumferential direction and the irregularly magnetized part 1b which is magnetized more intensely than any other part is formed at part of the magnetized part 1a. The magnetic sensor 3 which detects the arrival of the magnetized parts 1a and 1b is arranged below the drum 1. When the drum 1 is rotated by being driven by the rotary body fixed on a shaft 2, the output of the sensor 3 is sent out to the comparators 4A, 4B, and 4Z and compared with a reference voltage V0 or the sum of the voltage V0 and an offset voltage V1. Consequently, the comparators 4A, 4B, and 4Z output different kinds of signals.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a rotary encoder that detects the rotation speed, rotation angle, etc. of a rotating body based on the number and phase of pulses generated in accordance with the rotation of the rotating body. Regarding.

(Conventional technology) Conventionally, this kind of rotary encoder.

For example, the one shown in FIG. 3 is known. That is, in the figure, 11 is a magnetic drum, and this magnetic drum 11
is rotatable around a shaft 12 connected to a rotating body (not shown).

This magnetic drum 11 has a first magnetized portion 13 that is magnetized with N poles and S poles alternately along the entire circumferential direction.
and a second magnet with N and S poles magnetized in a part of the circumference.
The magnetized portion 14 is connected in the glaze direction.

Further, a magnetic sensor 15 made of a magnetic resistance element or the like is disposed below the magnetic drum 11, and a magnetic sensor 15 is provided below the first magnetized portion 13.
The output of the magnetic sensor 15 is applied to the non-inverting input terminals of the comparators 16A and 16B so as to obtain two types of pulses from the magnetic sensor I5, and the output of the magnetic sensor I5 is applied to the non-inverting input terminals of the comparators 16A and 16B so as to obtain two types of pulses from the second magnetized section 14. is applied to the non-inverting input terminal of comparator 16Z.

A common basic voltage V is applied to the inverting input terminals of each of the comparators 16A to 162. By rotating the magnetic drum 11 together with the rotating body with such a configuration, the output terminals of the comparators 16A and 16B output two-phase signals A, which are shifted by, for example, 174 cycles from each other.
B is obtained, and one pulse is obtained from the output terminal of the comparator 162 as a reference signal Z for each rotation of the magnetic drum 11.

(Problems to be Solved by the Invention) However, in this rotary encoder, in order to obtain the reference signal Z, the second magnetized portion 14 is attached to the magnetic drum 11.
As a result, the magnetic drum 11 becomes longer in the axial direction, and the magnetic sensor 15 also becomes correspondingly larger, resulting in an increase in the size of the encoder as a whole, leading to an increase in cost.

The present invention was proposed to solve the above problems, and its purpose is to reduce the size of the magnetic drum and magnetic sensor by devising a method for magnetizing the magnetic drum, thereby reducing costs. The objective is to provide a rotary encoder that makes it possible to

(Means for Solving the Problems) In order to achieve the above object, the present invention provides that a part of a magnetized part that rotates following a rotating body and is formed around a part is separated from other parts. a magnetic drum in which mutant magnetized parts having different magnetic forces are formed; a magnetic sensor that detects the arrival of the magnetized parts and the mutant magnetized parts and converts it into multiple types of signal voltages with different amplitudes; The present invention is characterized by comprising a plurality of comparators each receiving a reference voltage of 1 and outputting a detection signal of the magnetized section and the variation magnetized section, respectively.

(Function) In the present invention, the variant magnetized portion is magnetized with a stronger magnetic force than, for example, other magnetized portions. and.

When this variant magnetized section comes near the magnetic sensor due to the rotation of the magnetic drum, the magnetic sensor outputs a plurality of types of signal voltages depending on the difference in magnetic force between the magnetized section and the variant magnetized section. These signal voltages are input to a plurality of comparators having appropriately different reference voltages, and these comparators output detection signals corresponding to the magnetized portion and the variant magnetized portion.

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

First, FIG. 1 shows a schematic configuration of a rotary encoder according to the present invention, and in the figure, 1 is a disk-shaped magnetic drum that rotates with a rotating body (not shown) around a shaft 2. . This magnetic drum 1 has a magnetized portion 1a formed by alternately magnetizing N and S poles along its circumferential direction, and the magnetized portion 1a
A mutant magnetized portion 1b, which is more strongly magnetized than other portions, is formed in a portion of the magnet.

Below the magnetic drum 1 are a magnetized section 1a and a variant magnetized section 1.
A magnetic sensor 3 such as a magnetoresistive element or a Hall element is provided to detect the arrival of the magnetic drum 1, and the output a from the magnetic sensor 3 is a two-phase signal A' shifted by 1Z4 periods due to the rotation of the magnetic drum 1. , B'' as two comparators 4
It is added to the non-inverting input terminals of A and 4B. Also,
One of these signals B' is also applied to the non-inverting input terminal of another comparator 4Z;
is used to create a reference signal that generates one pulse per rotation of the magnetic drum 1.

Furthermore, a common reference voltage v0 is applied to the inverting input terminals of the comparators 4A and 4B, while the comparator 4Z
The sum of this reference voltage v0 and an appropriate offset voltage V□ is applied to the inverting input terminal of the . Here, the reference voltage v0 is a two-phase signal A'.

The offset voltage v2 is set to a value larger than the maximum value of the two-phase signal A″ 13 j.

Next, this operation will be explained with reference to FIG.

As the magnetic drum 1 rotates with the rotation of the rotating body, the two-phase signals A' and B' are shifted by 1Z4 periods from each other as shown in FIG. B' is input to comparators 4B and 4Z, respectively. At this time, comparators 4A and 4B
Reference voltage ■. Since is the average value of each signal A', B', output signals A, B as shown are obtained from the comparators 4A, 4B.

On the other hand, as the magnetic drum 1 rotates, when the mutant magnetized portion 1b comes directly above the magnetic sensor 3, it crosses the section T and 2
The amplitudes of phase signals A' and B' become larger.

Therefore, at this time, the maximum value of the signal B' applied to the non-inverting input terminal of the comparator 4z is the voltage (
Reference voltage V. and offset voltage V□), the output signal Z as shown can be generated from the comparator 4z within the section T.

In this embodiment, the signal B' is used as the input signal to the comparator 4z, but it goes without saying that the signal A' may also be input. Furthermore, the reference voltage of the comparator 4z is set to ■ by setting the offset voltage V□ larger than the average value v0. Although it is assumed to be 10V□, the basic voltage is V. −
(2) Substantially the same results can be obtained even if the setting is set to (2).

In addition, the mutant magnetized portion 1b may be configured to have a weaker magnetic force than the other magnetized portions 1a; in this case, the mutant magnetized portion 1b
The maximum value of the two-phase signals A' and B' according to
By setting the reference voltage of the comparator 4Z between the maximum value of the two-phase signals A' and B' according to be.

(Effects of the Invention) As detailed above, according to the present invention, if it is possible to obtain multiple types of output signals from a single magnetic drum by devising the magnetization method of the magnetic drum, it is possible to obtain multiple types of output signals from a single magnetic drum. Therefore, it is possible to provide a small and low-cost rotary encoder without increasing the size of a magnetic drum or a magnetic sensor corresponding to its structure.

[Brief explanation of the drawing]

1 and 2 show an embodiment of the present invention,
FIG. 1 is an explanatory diagram showing a schematic configuration, FIG. 2 is an explanatory diagram of operation, and FIG. 3 is a schematic diagram showing a conventional example. 1... Magnetic drum 1a... Magnetized part 1b...
・Mutation magnetized part 2...Shaft 3...Magnetic sensor 4A, 4B, 4Z...Convalley patent applicant Fuji Electric Co., Ltd. agent Patent attorney Mori 1) Yurisha-Te■6 Figure 2

Claims (1)

[Claims] A magnetic drum that rotates following a rotating body, and in which a mutant magnetized part having a different magnetic force from other parts is formed in a part of the magnetized part formed around the drum, and the magnetized part and the mutant magnetized part. A magnetic sensor detects the arrival of the magnetized part and converts it into multiple types of signal voltages with different amplitudes, and the signal voltage and a unique reference voltage are respectively inputted to generate detection signals of the magnetized part and the mutant magnetized part. A rotary encoder characterized by comprising a plurality of comparators each outputting an output.