JP3362558B2 - Rotary encoder - Google Patents

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,
In particular, the present invention relates to an incremental encoder used by being incorporated in a three-phase AC servomotor.

[0002]

2. Description of the Prior Art Servo motors used for driving various machines include DC servo motors with brushes and brushless A servo motors.
There are C servo motors (DC brushless servo motors), and in recent years, the demand for AC servo motors has increased due to the ease of motor maintenance.

There are various types of position detectors for servo systems, but in recent years, rotary encoders used by incorporating them in 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 they occupy the mainstream as encoders for AC servos. On the other hand, an absolute encoder is an encoder that can determine the absolute position within one revolution.
It is widely used in servo motors for large robots such as multi-joint robots because it does not require home-return operation.

A conventional incremental encoder will be described below. FIG. 8 shows the structure of a conventional incremental encoder. Reference numeral 81 is a light emitting element, 82 is a rotary slit plate, 83 is a light receiving element, 84 is a waveform shaping circuit, and 85 is a signal transmission circuit.

As shown in FIGS. 9 (a) and 9 (b), the output signals are A and B two-phase signals having a 90-degree phase difference from each other so that the rotation direction can be discriminated, and an origin reference Z of one pulse per one rotation. And a commutation signal CS1, CS2, CS3 for switching the phase excitation of the AC servo motor.

[0006]

However, in the above-mentioned conventional configuration, since the number of output signals is large, the number of wirings is large, so that mass productivity is poor, and erroneous wiring to equipment and disconnection of the signal line itself are likely to occur. There was a problem. In addition, there is a problem that the number of pulses of the rotary encoder and the information of the device such as the mounted motor are manually input on the receiving side.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an incremental 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, the incremental encoders according to the present invention are designed with 90
Outputs the A and B two-phase incremental signals having a phase difference, the reference signal Z indicating the origin during one rotation, and the three-phase AC servo motor phase excitation switching signals (commutation signals) CS1, CS2, and CS3 phases. The original signal output section, the power ON / OFF detection circuit that detects the ON / OFF state of the encoder main power supply, the changing edge of the A and B2 phases are detected, and the count up pulse and the down pulse are detected according to the phase of the A and B2 phases. A direction discrimination circuit for outputting, an up / down counter for preloading count initial data by the output of the power ON / OFF detection circuit and counting output pulses of the direction discrimination circuit, and the up / down depending on the levels of A and B phases. An initial value detection circuit for outputting initial data to be preloaded on the counter, a Z phase and a C from the original signal output section. A data latch circuit for latching 1, CS2, CS3 phases and data from the up / down counter, a Z signal conversion circuit for sampling the Z phase from the original signal output and outputting the Z phase state, and an external The serial signal command of the encoder allows the encoder parameters such as the number of pulses, the number of poles and the identification number of the rotary encoder, the number of the equipment such as the motor to be mounted, the induced voltage constant, the moment of inertia, the viscous coefficient and their temperature coefficient to be calculated. ROM or electrically rewritable ROM or nonvolatile RA for parameters of equipment such as motors
A circuit for writing and storing data in a RAM backed up by M or a battery, and count data output from the data latch circuit in response to an external serial signal command, and output from the CS1, CS2, CS3 phase and Z phase signal conversion circuits. Data, and a parallel-serial conversion circuit for converting the parameters of the rotary encoder and the parameters of the device such as a motor to serial data and outputting the serial data, and a conversion circuit for bidirectional serial communication.

[0009]

With this configuration, the A phase, B phase, Z phase, CS1 and C are switched by switching the command of the serial signal from the outside.
Since the signals of S2 and CS3, the parameters of the rotary encoder and the parameters of the device such as the motor can be transmitted as serial data on one line, the number of output signals from the encoder can be reduced and the mass production is highly reliable. A rotary encoder can be obtained.

[0010]

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

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

In FIG. 1, reference numeral 11 denotes an original signal output section, and 12
Is a direction discrimination circuit, 13 is an up-down counter, 14 is an initial value detection circuit, 15 is a parameter storage circuit, 16 is a data latch circuit, 17 is a Z signal conversion circuit, 18 is a parallel-serial conversion circuit, and 19 is a bidirectional buffer. Circuit, 2
Reference numeral 0 is a power ON / OFF detection circuit.

The original signal output section 11 is composed of a light emitting element 81, a rotary slit plate 82, a light receiving element 83, and a waveform shaping circuit 84 shown in FIG. 8 similarly to the conventional incremental encoder, and a typical example of the output signal is shown in FIG. Incremental signals A phase, B phase, Z phase, and 3-phase excitation switching commutation signals CS1, CS2, CS3 are output.

FIG. 2 is an operation waveform diagram of the direction discriminating circuit in the embodiment of the present invention. In FIG. 2, when A phase is ahead of B phase, a down pulse is output, and A phase is B
When the phase is later than the phase, an up pulse is output. The up pulse and the down pulse are input to the up / down counter 13 to count the pulses and change the count data.

FIG. 3 (a) is an operation waveform diagram of the initial value detection circuit in one embodiment of the present invention, and FIG. 3 (b) is an example of the circuit. A-phase and B-phase signals "H" and "L" are shown. ", 2-bit initial values D1 and D0 are output.

[0016] FIGS. 4 (a) is an operation waveform diagram of the up-down counter in an embodiment of the present invention, where 16
An operation example of the bit counter is shown. The up / down counter is a pulse counter in which the data preload operation and the count operation can be switched by the output of the ON / OFF detection circuit 20.

FIG. 4B is an overall operation waveform diagram of the up / down counter in one embodiment of the present invention.

FIG. 5 is a configuration diagram of serial data output from the parallel-serial conversion circuit in one embodiment of the present invention. In FIG. 5, one frame of data is composed of a start bit, a mode bit, a data bit, a parity bit, a stop bit, an idle bit and the like. The data latch signal for updating the data in the data latch circuit 16 is output in synchronization with the serial data frame as shown in FIG.

FIG. 6 is a block diagram of a Z signal conversion circuit according to an embodiment of the present invention. In FIG. 6, it comprises a Z-phase level detection circuit 61, a Z-phase passage detection circuit 62, a count change amount detection circuit 63, and a data shift circuit 64.

FIG. 7 is an operation explanatory diagram of the Z signal conversion circuit in the embodiment of the present invention. FIG. 7A shows the Z signal conversion state when the A, B, and Z phase outputs change for each frame of serial data, and FIG. 7B shows A, B within one frame of serial data. , Is a diagram showing a Z signal conversion state when the Z-phase output changes.

The operation of the rotary encoder having the above structure will be described below. First, parameters such as the number of pulses of the A phase and B phase of the rotary encoder, the number of poles, the identification number, and the number of the equipment such as the motor to be mounted, the induced voltage constant, and the inertia are set by an external serial signal command as parameter setting. The parameters of the device such as the motor such as the moment, the viscosity coefficient, and the temperature coefficient thereof are input to the 15 parameter storage circuits via the bidirectional buffer circuit 19, the parallel-serial conversion circuit 18, and the data latch circuit 16.

When the main power supply is turned on after the parameter setting is completed, each parameter data stored in 15 parameter storage circuits is output via the data latch circuit 16, the parallel / serial conversion circuit 18 and the bidirectional buffer circuit 19. . The output of this parameter data is continuously transmitted repeatedly for several seconds, or A phase, B phase, Z phase, CS1, CS2, CS are commanded by an external serial signal command.
3 shifts to the output state.

A phase, B phase, Z phase, CS1, CS2, CS
In the output state of 3, the original signal output unit 11 outputs A phase, B phase,
The Z-phase, CS1, CS2, and CS3 signals are detected, the signals are subjected to the following signal processing, and are output as a serial signal.

As the counter processing for the A phase and the B phase, for example, when the main power source is turned on at the position of FIG. 4A, the count value is the data preload value of the initial value "3" detected by the initial value detection circuit 14. When the shaft rotates to CW, the down pulse from the direction discriminating circuit 12 is counted, and the count value changes from 3 → 2 → 1 → 0 → 65535. After that, the counter is a cyclic counter as shown in FIG. 4 (b). To continue operating. The data of the counter, the Z phase of the original signal output section, and the CS1, CS2, and CS3 signals are data latched by the data latch circuit 16 every transmission cycle of serial data. Regarding the Z phase, the Z signal conversion circuit 17 converts the Z phase, the output Z ′ phase of the data latch circuit 16 and the value of the up / down counter into 2-bit state information Z1 and Z0.

The above count data, CS1, CS2
CS3 and Z1 and Z0 are parallel-serial conversion circuits 1
8 and the information is transmitted to the external system as serial data with the configuration shown in FIG.

As described above, all the information in the encoder is repeatedly transferred to the external system as serial data every predetermined time.

On the other hand, the external system receives the serial data, converts the count data, CS data, Z-phase state information, parameters of the rotary encoder and the parameters of the equipment to be mounted into parallel data, and then the count data and Z-phase. The state information and each parameter are used for controlling the position, speed, current, etc., and the CS data is used for exciting the motor.

Next, the operation of the Z signal conversion circuit 17 will be described with reference to FIGS. In FIG. 6, a Z-phase level detection circuit 61 is a circuit that detects Z-phase “H” and “L” for each transmission cycle of serial data. The Z-phase passage detection circuit 62 is a circuit that detects changes in the Z-phase within the transmission cycle of serial data and detects whether the Z-phase has passed within the cycle. The count change amount detection circuit 63 is a circuit that detects the change amount of the counter data for each serial data transmission cycle, and cancels the Z-phase passage information of the Z-phase passage detection circuit when the change amount is less than or equal to a predetermined amount. The data shift circuit 64 is a circuit that generates Z-phase state information Z1 and Z0 signals from the Z-phase level detection circuit and the Z-phase passage detection circuit. Here, of the Z-phase state information 2 bits Z1 and Z0, Z
1 indicates "H", "L" of the Z phase one frame before or "pass" and "no pass" of the Z phase by "1" and "0",
Z0 is "H", "L" or Z of the Z phase in the current frame
The phases "passed" and "passed" are indicated by "1" and "0".

FIG. 7A is a diagram showing the operation of the Z-phase level detection circuit and the data shift circuit. Z when the A, B, and Z-phase outputs change for each frame of serial data.
The signal conversion state is shown. At the point h, the Z phase is "L", so the outputs Z1, Z0 of the data shift circuit are 0, 0. At the point i, the Z phase is "H", Z1, Z0 are 0, 1, and at the point j, Z.
Since the phase is “H”, Z1 and Z0 are 1,1 and at the point k, the Z phase is “L” and Z1 and Z0 are 1,0.

FIG. 7B is a diagram showing the operation of the Z-phase passage detection circuit, the count change amount detection circuit, and the data shift circuit. The A, B, and Z phase outputs change within one frame of serial data. The Z signal conversion state at this time is shown. At the point m, the Z-phase passage detection circuit detects that the Z-phase has passed, but since the count value has not changed by the count change amount detection circuit, the position has returned to the original position, so the "passage" information is canceled. Then, Z1 and Z0 become 0 and 0.
On the other hand, at point O , the Z-phase passage detection circuit detects that the Z-phase has passed, and the count change amount detection circuit changes the count value.
1, Z0 becomes 0,1. Since the count change amount is always 3 or more when the Z-phase has passed, the change amount detection circuit determines that the count change amount 2 or less is canceled, and the change amount 3 or more is not canceled.

In this way, the Z-phase state information is set to 2 bits,
In addition, by converting the states of the two frames, the current frame and the immediately preceding frame, into information, it is possible to discriminate the information by the front and rear serial data even if data is lost due to noise or the like.

With the above configuration, the number of signals can be set to one line by serially transmitting the count data, the commutation data, the Z-phase information, the parameters of the rotary encoder, the parameters of the mounted motor, etc.
It is possible to reduce the number of wiring steps of the device and improve the reliability against disconnection of the signal line.

Further, the count data of the A and B phases and Z
By transmitting the phase information with 2 bits, even if the serial data is received wrongly by the external system due to the external noise, the normal information can be obtained if the next data is normally received, so that the reliability is high. A wire-saving system can be built.

[0034]

As described above, according to the present invention, the A phase, B phase, Z
By serially transmitting the phase, CS1, CS2, CS3 signals, parameters of the rotary encoder, and parameters of the mounted motor, it is possible to reduce the number of signal lines required from 14 in the past to 4 and to achieve mass productivity. And a highly reliable rotary encoder can be realized.

[Brief description of drawings]

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

FIG. 2 is an operation explanatory diagram of a direction discrimination circuit according to an embodiment of the present invention.

FIG. 3 is an operation explanatory diagram of an initial value detection circuit according to an embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of an up-down counter according to an embodiment of the present invention.

FIG. 5 is a serial data configuration diagram according to an embodiment of the present invention.

FIG. 6 is a configuration diagram of a Z signal conversion circuit according to an embodiment of the present invention.

FIG. 7 is an operation explanatory diagram of the Z signal conversion circuit in the embodiment of the present invention.

FIG. 8 is a conventional rotary encoder configuration diagram.

FIG. 9 is a conventional rotary encoder operation waveform diagram.

[Explanation of symbols] 11 Original signal output section 12-way discrimination circuit 13 Up-down counter 14 Initial value detection circuit 15 Parameter memory circuit 16 Data latch circuit 17 Z signal conversion circuit 18 Parallel-serial conversion circuit 19 Bidirectional buffer circuit 20 Power ON / OFF detection circuit 61 Z-phase level detection circuit 62 Z-phase passage detection circuit 63 Count change amount detection circuit 64 data shift circuit 81 Light emitting element 82 Rotating slit plate 83 Light receiving element 84 Waveform shaping circuit 85 signal transmission circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01D 5/00-5/62 G01B ⁷ /00-7/34

Claims (4)

(57) [Claims] 1. An incremental signal of two phases A and B having a phase difference of 90 degrees, a reference signal Z indicating an origin during one rotation, and a phase excitation switching signal (commutation signal) CS1 of a three-phase AC servomotor. An original signal output section for outputting the CS2 and CS3 phases and turning on the encoder main power supply,
A power ON / OFF detection circuit for detecting the off state, A,
A direction discriminating circuit that detects a change edge of the B2 phase and outputs a count up pulse and a down pulse according to the phases of the A and B2 phases, and a count initial data that is preloaded by the output of the power ON / OFF detection circuit to preload the direction discriminating circuit An up / down counter for counting output pulses, an initial value detection circuit for outputting initial data to be preloaded in the up / down counter according to the levels of A and B2 phases, Z phase and CS1, C from the original signal output section.
A data latch circuit for latching the S2 and CS3 phases and the data from the up / down counter, and Z for sampling the Z phase from the original signal output and outputting the Z phase state.
By the signal conversion circuit and the command of the serial signal from the outside, encoder parameters such as the pulse number of the rotary encoder, the number of poles and the identification number, the number of the equipment such as the mounted motor, the induced voltage constant, the moment of inertia and the viscosity coefficient ROM or electrically rewritable ROM for device parameters such as motors and their temperature coefficients
Alternatively, a circuit for writing and storing in a nonvolatile RAM or a RAM backed up by a battery, and count data output from the data latch circuit in response to an external serial signal command, CS1, CS2, CS3 phase and Z phase signal conversion A rotary encoder equipped with a parallel-serial conversion circuit that switches the data output from the circuit and the parameters of the rotary encoder and the parameters of equipment such as a motor to convert into serial data and outputs the serial data, and a conversion circuit for bidirectional serial communication. 2. A Z-phase level detection circuit for detecting a Z-phase state in synchronization with a cycle of serial data, and a Z-phase passage detection for detecting a Z-phase state of an original signal output section within a cycle of serial data. A circuit, a count change amount detection circuit that detects a change amount of an up / down counter for each cycle of serial data, and cancels passage information of the Z-phase passage detection circuit when the change amount is equal to or less than a set value; 2. The rotary encoder according to claim 1, further comprising a Z signal conversion circuit including a data shift circuit for outputting Z-phase state information in 2 bits from the level detection circuit and the Z-phase passage detection circuit. 3. The Z-phase state information 2-bit is composed of a Z-phase state 0/1 detected in the current cycle of the serial data and a state 0/1 detected in the immediately preceding cycle. Alternatively, the rotary encoder according to claim 2. 4. The rotary encoder according to claim 1, further comprising a count change amount detection circuit for canceling the Z-phase passing information when the count change amount is 2 or less.