JPS60233516A - Transducer - Google Patents

Abstract

PURPOSE:To write optionally data corresponding to a slit after assembling a transducer by writing two period data of a different phase different at a prescribed pitch in a detecting plate which moves in accordance with a rotation of an object, and detecting said data. CONSTITUTION:Two period data of different phase differences are written at a prescribed pitch through magnetic heads 22a, 22b in a rotary plate 21 of ferrite, etc. which rotates in accordance with rotation of an object to be detected and can magnetize a magnetic material. These data are read by magneto-resistance elements 25a, 25b, etc., and an encoded signal is outputted through waveform circuits 28, 29. According to this constitution, data corresponding to a slit of a rotary encoder can be written optionally after assembling a transducer, and a transducer which can change easily resolution and a rotational angle to match a control system is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transducer that converts a rotational angle, rotational speed, or linear displacement or direction of a detected object into a digital signal.

Prior art and its problems A conventional transducer, for example a rotary encoder, is fixed to a shaft 1 as shown in Fig. 6, and a light emitting diode or the like is projected through a rotating slit 2 with a predetermined bright and dark pattern formed on the circumference. The optical elements 3゜4 are arranged facing each other, and two corresponding light receiving elements 6 are connected through a fixed slit 5 having a notch base facing each other at the position of each light emitting diode 3゜4.
, 7 were placed. Then, the shaft 1 is rotated to receive the optical signals from the light emitting elements 3 and 4 through the slits 2.5, and the outputs of the respective light receiving elements 6 and 7 are amplified by the amplifiers 8.9, and then sent to the waveform shaping circuit. By performing waveform shaping according to 10.11, two-phase outputs were obtained, A and B.

According to such a rotary encoder, by arranging the rotating slit 2, the fixed slit 5, and the light receiving areas of the light receiving elements 6 and 7 as shown in FIG. 7, the output A of the waveform shaping circuit 10.11.

B can be extracted as outputs with different phases in correspondence with the rotational direction of the shaft 1. Now, if the slit width of the fixed slit is p, then by setting the pinch between the light receiving elements 6 and 7 to rlpf p/2 (n is a positive integer), the rotational direction of the shaft 1 can be adjusted from the two waveform shaping circuits 10° 11. It is possible to obtain two-phase outputs A and B whose phases lead or lag by 90°, respectively. This phase difference makes it possible to detect the direction, and depending on the number of pulses, it is possible to detect the rotation speed and rotation angle of the object to be detected, and in the case of a linear encoder, it is possible to detect the amount of displacement.

However, with the diversification of control systems in recent years, encoders are also required to be more diverse, and encoders are required whose resolution of the rotational axis of the shaft 1 is matched to each control system. For this reason, it is necessary to improve the resolution of the encoder and to prepare many types of encoders having various resolutions. However, the bright and dark parts of the rotating slit 2 are constructed by metal etching and glass plate vapor deposition, but the pinch between bright and dark parts and the pitch width between AB are determined geometrically, so many processes are required for manufacturing. , could not be easily changed. Furthermore, since the rotating slit 2 is fixed to the shaft 1 and the fixed slit 5 to the encoder housing using extremely precise assembly techniques, these slits cannot be easily replaced, and various problems can be achieved by replacing only the slits. There was a problem in that it was not possible to meet the resolution requirements for the control system.

Purpose of the Invention The present invention has been made in view of the problems of conventional transducers such as rotary encoders and linear encoders. The purpose of the present invention is to provide a transducer that can easily change the resolution and rotation angle according to the control system.

Structure and Effects of the Invention The present invention is a transducer that obtains an electrical signal based on a signal from a detection plate that moves in response to the movement of an object, and in which the detection surface of the detection plate has different phase differences at a predetermined pitch. a data writing section that writes two periodic data having a 1.degree. The first waveform shaping the output of the second reading section. A second waveform shaping circuit is provided.

According to the present invention having such characteristics, after mechanically configuring a transducer having a detection plate, two-phase periodic data having different phase differences is written in accordance with the usage state of the transducer. This makes it possible to create a transducer whose resolution and rotation angle can be easily changed in accordance with the system in which it is used. Therefore, there is no need to prepare a large number of detection plates according to specifications, and it is possible to obtain a transducer that can be used in a variety of systems with a small number of products.

DESCRIPTION OF THE EMBODIMENTS FIG. 1 is a block diagram showing the basic configuration of a rotary encoder according to an embodiment of the present invention.

In this figure, a shaft 20 rotates in response to the rotation of an object to be detected (not shown), and a rotary plate 21, which is a detection plate, is integrally provided on the shaft. The rotary plate 21 is a rotary plate whose surface has been treated with a material capable of magnetizing a magnetic substance, such as ferrite. At one end of the surface of the rotating plate 21, two magnetic heads 22a and 22b are arranged in the diametrical direction of the rotating plate 21, as shown in the figure. The magnetic heads 22a, 22b have an A-phase writing circuit 23 and a B-phase writing circuit 23, respectively.
The rotating plate 21 is annularly magnetized by their output. Magnetic detection elements, such as magnetoresistive elements 25a and 25b, for detecting the magnetized state are arranged on the same circumference of the magnetic heads 22a and 22b of the rotating plate 21, respectively. The outputs of these magnetoresistive elements 25a and 25b are transmitted to waveform shaping circuits 28 and 29 via amplifiers 26 and 27, where the waveforms are shaped and square wave signals are taken out as two-phase A and B outputs.

Here, the minimum detection width W m of the magnetoresistive elements 25a and 25b
i n is the maximum resolution of this rotary encoder,
In other words, the maximum number of pulses that can be obtained per revolution is N max
Then, it is expressed as πR/Nmax (where R is the radius of the ring to be magnetized). The magnetoresistive elements 25a and 25b can be arranged at an arbitrary pitch by simply shifting the phase of magnetization by magnetic writing. Now, from the A phase write circuit 23 and the B sum write circuit 24, the magnetic heads 22a and 22
Assume that magnetization is performed using b as shown in FIG.

Here, the annular magnetized state of the rotary plate 2I is expressed by stretching it into a straight line as shown. In this way, when the magnetoresistive elements 25a and 25b are at the positions shown in the figure, the magnetized state is detected by the magnetoresistive elements 25a and 25b, and amplified by the amplifiers 26 and 27, as shown in FIG.
, (The waveforms shown in bl are obtained.By shaping these outputs with waveform shaping circuits 28 and 29, it is possible to obtain outputs with a phase shift of 90' as shown in Figure 3 (C1, (d)). As with conventional rotary encoders, if the rotation direction is different, the phase difference is reversed, so it is possible to detect the rotation direction.

Further, in the case of a rotary encoder in which a resolution N equal to the maximum resolution Nwax is sufficient, the magnetization pitch difference Xn between the two magnetoresistive elements 25a and 25b in the magnetized state shown in FIG. 4 is given by the following equation. Therefore, by changing the magnetization pitch difference Xn while maintaining this relationship for any resolution number N, a phase difference of 90' can be obtained from the waveform shaping circuits 28 and 29. For example, if N max is 10000, W
When min is an encoder with a 10μ sheath, 2000
If a resolution of
If so, it is possible to obtain an encoder with a resolution of 2000 and a phase difference of 90°. In this way, Figure 5(a)
, As shown in (b), signals having a phase difference of 90° are obtained from the amplifiers 26 and 27, and a square wave output can be obtained by shaping the waveforms using the waveform shaping circuits 28 and 29. As described above, according to the present invention, it is possible to obtain an encoder with arbitrary resolution, and it is also possible to obtain an arbitrary phase difference as required.

In this embodiment, one magnetoresistive element is used for each of the A and B phases to detect the magnetized state. By the way, when increasing the maximum resolution, the minimum detection width of the magnetoresistive element W m f n
However, if the detection signal becomes small, it is possible to obtain an output with a good S/N ratio by using a plurality of magnetoresistive elements in parallel and adding and amplifying their outputs.

Furthermore, in this embodiment, a rotary encoder that can be arbitrarily rewritten using magnetism is constructed, but the present invention can also be applied to a linear encoder as it is, and is not limited to magnetic recording. It is also possible to configure

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the basic configuration of a rotary encoder according to an embodiment of the present invention, and Fig. 2 is a diagram showing the relationship between the magnetized state and the magnetoresistive element when magnetized at the minimum pitch. , Figure 3 is a waveform diagram showing the waveforms of each part obtained at that time, Figure 4 is a diagram showing the magnetized state when the maximum resolution is x, and Figure 5 is a diagram showing the magnetized state obtained at that time. FIG. 6 is a diagram showing an example of a conventional rotary encoder, and FIG. 7 is a diagram showing the positional relationship of its slits. 20---One...-Shaft 21---One rotating plate
22a. 22b-----One magnetic head 23-----A phase write circuit 24---B sum write circuit 25 a
, 25 b - - - Magnetoresistive element 26 , 27
-------Amplification circuit 28゜29-...-Waveform shaping circuit Fig. 1 26 Fig. 2 Fig. 3

Claims (3)

[Claims] (1) In a transducer that obtains an electrical signal based on a signal from a detection plate that moves in response to the movement of an object, two periods having different phase differences at a predetermined pitch are provided on the detection surface of the detection plate. a data writing section that writes the data, and a first section that detects the two-phase data written on the detection plate by the data writing section. a second reading section; and the first reading section. Second
The first step is to waveform shape the output of the reading section. A transducer comprising: a second waveform shaping circuit. (2) The detection plate is made of a magnetic material to which a magnetic body is magnetized, the data writing section has a magnetic head for writing magnetic data, and the first... 2. The transducer according to claim 1, wherein the second reading section has a magnetic detection element that detects magnetic data written on the detection plate. (3) The detection plate is a rotary plate provided on a shaft that rotates in response to the movement of an object, and obtains an output corresponding to the amount of rotation.
Transducer as described in section.