JPH05107081A - Rotary encoder - Google Patents

Abstract

PURPOSE:To provide a rotary encoder high in mass producibility and in reliability with a reduction in the number of output signals by arranging a bit converting circuit to convert incremental signals of two phases and an origin signal into 2-bit signals. CONSTITUTION:Among incremental signals A and B to be obtained through a light emitting element 11, a rotary slit plate 12, a photodetecting element 13 and a waveform shaping circuit 14, an origin signal Z and three phase excitation switching signals U, V and W, the three signals A, B and Z are converted into bit signals A' and B' having the phase A and B signals inverted with a bit conversion circuit 15 to output when the signal Z is active. In other words, conditions are applied to allow the phase Z to change when changes in signals of the phases A and B appear simultaneously and a bit signal having information of the phase Z contained in the phases A and B can be outputted in two circuits. This achieves a curtailment of the number of signal lines and higher mass producibility and reliability of the apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary encoder for detecting the rotational position of a rotating body.

[0002]

2. Description of the Related Art Recently, brushless DC servomotors and brushless AC servomotors (DC brushless servomotors) are used as servomotors for driving various machines.
Therefore, the demand for AC servomotors is increasing due to the ease of motor maintenance.

Although there are various types of position detectors for servo systems, rotary encoders used by incorporating them into servo motors have become widespread. Encoders incorporated in AC servomotors are roughly classified into incremental encoders and absolute encoders. Incremental encoders are widely used by being attached to AC servo motors of various machines, and are dominated as AC servo encoders. On the other hand, an absolute encoder is an encoder that can determine the absolute position within one rotation, and since it does not require a return-to-origin operation, it is widely used in servomotors for large robots such as articulated robots.

A conventional rotary encoder will be described below. As shown in FIG. 4, the rotary encoder includes a light emitting element 41, a rotary slit plate 42, a light receiving element 43, a waveform shaping circuit 44, and a signal transmission circuit 45.

The operation of the rotary encoder configured as described above will be described. The light output from the light emitting element 41 passes through the rotary slit plate 42, and then a plurality of light receiving elements 43 arranged to generate respective signals as shown in FIG. That is, as shown in FIG. 5, the output signals are A and B two-phase signals having a phase difference of 90 degrees so that the rotation direction can be discriminated, an origin reference Z signal for generating one pulse per rotation, and an AC servo. Commutation signals U, V, W for switching the phase excitation of the motor are provided.

[0006]

However, in the above-mentioned conventional configuration, since the number of output signals is large, the number of wirings is large, mass productivity is poor, and erroneous wiring to equipment and disconnection of the signal line itself are likely to occur. There was a point.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a rotary encoder which reduces the number of output signals of the encoder and has high mass productivity and high reliability.

[0008]

In order to achieve this object, a rotary encoder of the present invention uses an incremental signal of A and B phases having a phase difference of 90 degrees with each other and a reference signal Z indicating the origin during one rotation. And a phase excitation switching signal (commutation signal) U of the three-phase AC servo motor,
An original signal output section for outputting V and W3 phases, and A and B phase signals as they are when the Z signal is inactive from the A and B phase signals, and A and B phases and Z when the Z signal is active.
It has a bit conversion circuit that takes the exclusive OR of the phases and outputs a signal in which the logic level of each phase is the reverse of the normal pattern, and transmits the signals for the three phases A, B, and Z through two lines. It has such a configuration.

[0009]

With this configuration, since the 3-bit signals of A, B, and Z phases can be transmitted as 2-bit signals on 2 lines, the number of output signals from the encoder can be reduced, and the mass productivity is excellent and the reliability is high. A rotary encoder can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the rotary encoder includes a light emitting element 11, a rotary slit plate 12, a light receiving element 13, a waveform shaping circuit 14, a bit conversion circuit 15, and a signal transmission circuit 1.
It is composed of 6.

The operation of the rotary encoder configured as described above will be described with reference to FIGS. 1, 2 and 3. First, of the incremental signals A and B, the origin signal Z, and the three-phase excitation switching signals U, V, and W obtained through the light emitting element 11, the rotary slit plate 12, the light receiving element 13, and the waveform shaping circuit 14, of A, B, and Z. For the three signals, the bit conversion circuit 15 outputs a signal obtained by inverting the A and B phase signals when the Z signal is active. As a concrete example, FIG.
Shows the bit conversion circuit. This is the information of Z signal A, B
It is a circuit included in the phase signal. FIG. 3 is a timing pattern diagram of the signal generated at this time. The upper three signals in FIG. 3 are A, B, and Z phase signals input to the bit conversion circuit 15. The lower two signals A'and B'are bit patterns of A phase and B phase, respectively, which contain Z phase information encoded by this circuit. As shown in this figure, A ',
Assuming that the B ′ phase is 2 ¹ and 2 ⁰ bit signals, the signals input to the bit conversion circuit 15 are A and B phases when the Z phase is inactive and the encoder is moving in the forward direction. Is circulated while maintaining the humming distance of 1 as in 0 → 2 → 3 → 1 → 0 → 2 → 3 → 1 → 0 → 2, but when the Z phase is in the active state, A, Outputs a signal that is the reverse logic of each bit of phase B, and changes from 0 to 3 as in 0 → 3 → 1 → 0 → 2 → 1 → 0 → 2 → 3 → 1 ... , And irregular bit changes that are different from usual such that the Hamming distance becomes 2. That is, it is possible to output a bit signal including Z phase information in the A and B phases by two lines by giving a condition that the Z phase changes when signal changes in the A and B phases simultaneously occur. Become.

In the conventional rotary encoder having the above-mentioned structure, when the differential output system is used to transmit 6 signals, a total of 14 electric wires including the power supply are required. However, in this system, the power supply is included. Since 5 signals are transmitted, a total of 12 electric wires can be used.

[0014]

As is apparent from the above-described embodiments, the present invention can reduce the number of signal lines, which was conventionally required from 14 to 12, to 12, thus improving the mass productivity and the reliability of the excellent rotary. It is possible to realize an encoder.

[Brief description of drawings]

FIG. 1 is a block diagram of a rotary encoder circuit according to an embodiment of the present invention.

FIG. 2 is a bit conversion circuit diagram of the above.

FIG. 3 is an operation waveform diagram of the rotary encoder.

FIG. 4 is a block diagram of a conventional rotary encoder circuit.

[FIG. 5] Same as the above, operation waveform diagram of the rotary encoder

[Explanation of symbols]

 11 light emitting element 12 rotating slit plate 13 light receiving element 14 waveform shaping circuit 15 bit conversion circuit 16 signal transmission circuit

Claims (1)

[Claims] 1. A and B2 having a phase difference of 90 degrees from each other.
Phase signal incremental signal, reference signal Z indicating the origin during one rotation, original signal output section for outputting phase excitation switching signals U, V, W of 3-phase AC servo motor, and A and B phase signals To A when the Z signal is not active,
Bit conversion in which the B-phase signal is left as it is, and when the Z signal is active, an exclusive OR of the A and B phases and the Z phase is obtained, and a signal in which the logic level of each phase is reversed from the normal pattern is output. It has a circuit and outputs signals for three phases of A, B and Z phases.
A rotary encoder that has the function of transmitting on a line.