JP2001074503A - Encoder and motor driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To highly accurately detect rotational speed by simple constitution by generating time data from a clock signal based on the timing of a sampling signal, and converting rotational position data and time data to serial signals to output them. SOLUTION: A time counter 8 counts the clock signal of a clock generator 6 to output a time count value, and a positional pulse generating time register 9 latches the time count value to accumulate the rotational position pulse generating time value at every generation of a rotational position pulse signal. Next, a time data register 10 latches the rotational position pulse generating time value by a sampling signal of a fixed period output from a fixed period counter 7 to output to a serial data converter 11. At this time, since the clock frequency of the clock generator 6 can be given a sufficiently high value, a speed detection signal of high accuracy is obtained, and by using a fixed period counter 7 for generating both of the rotational position data and the time data the constitution for detection of the rotational speed can be simplified.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder and a motor driving device, and more particularly to an encoder for outputting a serial signal and a motor driving device using the same.

[0002]

2. Description of the Related Art A rotary encoder for outputting a two-phase pulse has been used as a conventional rotary position detecting encoder. This pulse output encoder has a disk inside which slits are accurately carved at regular intervals, applies light to the slits, and pulse-shapes a signal obtained from the transmitted light to output. More usually, this encoder
In order to output information on the rotation direction, a two-phase pulse is output together with a pulse signal output shifted by 1/4 of the slit pitch.

[0003] However, such a pulse output encoder has a drawback that the number of signal lines is large, and if an error occurs in a pulse signal in a transmission line from the encoder to the rotation speed control device, a detection position shift occurs. was there. For this reason, especially in a servo motor using a permanent magnet type synchronous motor, a serial signal output encoder that counts rotational position pulses inside the encoder, converts the count value into a serial signal, and transmits the serial signal to a motor control device. Is becoming mainstream.

A conventional serial output encoder will be described with reference to FIG. FIG. 6 is a block diagram of a conventional serial output encoder. The motor or the rotating plate 1 driven by the motor has slits cut at equal intervals. LED2 on the part where this slit is
, And a rotational position pulse signal whose waveform is shaped by a slit transmission signal detector that detects the transmitted light,
This is sent to the rotation position pulse counter 4. The rotation position pulse counter 4 counts the rotation position pulse signal and outputs a rotation position pulse count value to the rotation position data register 5. The rotational position data register 5 latches the rotational position pulse count value by a sampling signal of a constant period outputted from the constant period counter 7 and outputs the serial data converter 11 as rotational position data.
Output to Note that the constant period counter 7 generates a sampling signal from the clock signal of the clock generator 6.
The rotational position data thus obtained is output from the serial data converter 11 as a serial signal to the outside.

[0005] The serial signal output in this manner is converted into rotation speed data by a speed detector in the motor speed controller 20. The method is as follows.

N = ΔP / ΔTs Here, N is the detected rotational speed, and ΔP is the incremental value of the number of rotation position pulses of the encoder which has been increased in one sampling cycle (the cycle of the above-described fixed cycle counter in the encoder). Yes, ΔTs is the period of rotation position data sampling.

[0007] As related to the prior art, there is one disclosed in Japanese Patent Application Laid-Open No. Hei 10-285981.

[0008]

However, when the rotation speed is detected by such a conventional method, the rotation speed detection value N is considered in consideration of the fact that the sampling period ΔTs of the number of rotation position pulses of the encoder is a constant value. Is 1 / ΔT
s. This value is a considerably large value. For example, when the number of rotation position pulses of the encoder is 2000 pulses / rotation and the rotation position data sampling period of the encoder is 1 ms, the resolution of the rotation speed detection value is 2π / 2000 / 0.001 = 3. .14 [rad / s]
(30 [rpm]).

With the resolution of the detected rotational speed value as described above, it is difficult to use it for speed control with high accuracy. Particularly in a high-response speed control system, speed fluctuations due to the resolution of the detected rotational speed value may occur. I do. In order to increase the resolution of the rotation speed detection value, it is conceivable to lengthen the sampling cycle of the rotation position data of the encoder or increase the number of rotation position pulses per one rotation of the encoder. There have been problems such as a decrease in system performance and an increase in encoder cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide an encoder and a motor drive device which can obtain a high-accuracy rotational speed detection value with a simple configuration and have a high speed control response.

[0011]

A first feature of the present invention to achieve the above object is that a rotation position pulse generating means for detecting rotation of a motor and generating a rotation position pulse signal;
A rotation position data generation unit that generates rotation position data based on a timing of a sampling signal of a predetermined period from the rotation position pulse signal, and a time data generation unit that generates time data based on a timing of the sampling signal from a clock signal; And a serial data converter for converting the rotational position data and the time data into a serial signal and outputting the serial signal.

A second feature of the present invention is that a rotation position pulse generating means for detecting a rotation of the motor to generate a rotation position pulse signal, and a rotation rotation based on a timing of a sampling signal having a predetermined period from the rotation position pulse signal. Rotation position data generation means for generating position data, time data generation means for generating time data from a clock signal based on the timing of the sampling signal, converting the rotation position data and the time data into serial signals and outputting the serial signals And the cycle of the clock signal is shorter than the cycle of the sampling signal.

A third feature of the present invention is that a rotation position pulse generating means for detecting rotation of the motor to generate a rotation position pulse signal, and for counting the rotation position pulse signal to generate a rotation position pulse count value. A rotation position data generating means for generating rotation position data by latching the rotation position pulse count value with a sampling signal of a predetermined period, and generating a time count value by counting clock signal pulses; It is provided with time data generating means for generating time data by latching with a sampling signal of a predetermined period, and a serial data converter for converting the rotational position data and the time data into serial signals and outputting the signals.

A fourth feature of the present invention is that a clock generator for generating a clock signal having a predetermined cycle, a constant cycle counter for generating a sampling signal having a predetermined cycle longer than the clock signal from the clock signal, and A rotational position pulse generating means for detecting and generating a rotational position pulse signal; a rotational position pulse count value generated by counting the rotational position pulse signal; and latching the rotational position pulse count value with the sampling signal to rotate the pulse signal. A rotation position data generating means for generating position data; a clock signal pulse of the clock generator being counted to generate a time count value; and the time count value is latched by a sampling signal of the fixed period counter to obtain time data. Time data generating means for generating the rotation position data and the time data as a serial signal In that a serial data converter for converting and outputting.

According to a fifth aspect of the present invention, there is provided a motor, an encoder, and a speed controller, wherein the encoder detects rotation of the motor and generates a rotation position pulse signal; A rotation position data generation unit configured to generate rotation position data based on a timing of a sampling signal having a predetermined period from a position pulse signal; a time data generation unit configured to generate time data based on a timing of the sampling signal from a clock signal; A serial data converter for converting the rotational position data and the time data into a serial signal and outputting the serial signal, wherein the speed control device detects a serial signal output from the encoder and outputs a speed detection value. The speed control is performed by comparing the speed detector with the speed command value output from the speed detector. In that a configuration and a speed control means.

According to a sixth aspect of the present invention, there is provided a motor, an encoder, and a speed control device, wherein the encoder detects a rotation of the motor and generates a rotation position pulse signal; A rotation position data generating means for generating a rotation position pulse count value by counting the position pulse signal, latching the rotation position pulse count value with a sampling signal of a predetermined period to generate rotation position data, and counting clock signal pulses A time counter for generating a time count value, and latching the time count value with the rotation position pulse signal to generate a rotation position pulse generation time value. Time data generating means for generating time data by latching at a time, the rotational position data and the time data A speed detector that converts a serial signal into a serial signal and outputs the speed signal, wherein the speed controller detects a serial signal output from the encoder and outputs a speed detection value; and a speed detector. Speed control means for controlling the speed by comparing a speed detection value and a speed command value output from the speed sensor, the speed detector processes a serial signal output from the encoder, and outputs position pulse number data and Serial signal processing means for separately outputting the pulse generation time data, position pulse number difference means for calculating a difference between the position pulse number data at each sampling timing, and a difference between the pulse generation time data at each sampling timing. And a pulse generation time difference means for calculating the difference value of the position pulse number difference device by the difference value of the pulse generation time difference device In that a configuration and a division means for outputting a degree detection value.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram of a serial encoder of the present invention, FIG. 2 is a block diagram of a motor drive device of the present invention, FIG. 3 is an explanatory diagram showing a temporal change of a position pulse count value in the present invention, and FIG. FIG. 5 is a block diagram of a speed detector of the speed control device according to the present invention. The same reference numerals in FIGS. 1 to 5 as those in FIG. 6 of the conventional example indicate the same or corresponding components.

In FIG. 1, a motor or a rotary plate 1 driven by the motor has slits cut at equal intervals. LED where this slit is
2, a slit transmission signal detector that detects the transmitted light forms a rotation position pulse signal whose waveform has been shaped, and sends the rotation position pulse signal to the rotation position pulse counter 4. The rotating plate 1, the LED 2, and the slit transmission detecting means 3 constitute a rotating position pulse generating means. The rotation position pulse counter 4 counts the rotation position pulse signal and stores the rotation position pulse count value in a rotation position data register 5.
Output to In this rotation position data register 5,
The rotational position pulse count value is latched by a constant period sampling signal output from the constant period counter 7 and output to the serial data converter 11 as rotational position data. The rotation position pulse counter 4 and the rotation position data register 5 constitute a rotation position data generating means. Note that the constant period counter 7 generates a sampling signal from the clock signal of the clock generator 6.

On the other hand, the time counter 8 counts the clock signal of the clock generator 6 and sends the time count value to the position pulse generation time register 9. Here, the clock frequency of the clock generator 6 can be set sufficiently higher than the sampling frequency of the encoder position signal. As a result, a highly accurate speed detection signal can be obtained. Further, since the position pulse generation time is counted using the clock signal for generating the sampling signal of the fixed period counter 7, the configuration can be further simplified. The position pulse generation time register 9 latches the time count value each time the rotation position pulse signal is generated, and temporarily stores the time when the rotation position pulse is generated. Next, in the time data register 10, the value of the pulse generation time register 9 is latched by a fixed period latch signal output from the fixed period counter 7, and time data is generated and output to the serial data converter 11. The time counter 8, the position pulse generation time register 9, and the time data register 10 constitute a time data generation unit. Here, the rotation position data,
Since the timing for sampling the time data is generated by the constant period counter 7 in the encoder, the constant period counter 7 can be used for both the generation of the rotational position data and the time data, and the configuration can be further simplified. It does not need to be created externally, i.e. by a signal from the speed controller 20. The rotational position data and time data of position pulse generation obtained as described above are
The signal is converted as a serial signal and output to the outside.

In FIG. 2, a rotational position detecting encoder 24 is directly attached to a shaft of a motor 23 to be controlled. The serial output signal of the rotational position detection encoder 24 is input to a speed detector 25 in the speed control device 20 and is converted into a detected speed value Ndet. Next, in the comparator 26, the speed command value Nre given to the speed control device 20 is obtained.
The difference between f and the speed detection value Ndet is obtained, and this difference is given to the speed controller 21. The speed controller 21 gives an output current command to the current amplifier 22 in order to reduce the speed deviation to 0, whereby the current amplifier 22 outputs a motor drive current. Thus, the motor 23 is automatically driven to rotate at a speed following the speed given by the speed command value Nref. The comparator 26, the speed controller 21, and the current amplifier 22 constitute a speed control unit.

Referring to FIG. 3, the rotational position data and the rotational position pulse generation time data obtained by the above method will be described. FIG. 3 shows the change in the rotation position pulse count value with respect to time when the rotary plate with slit 1 in the encoder 24 is rotating. Here, S0, S1, S2,... Indicate the position data sampling timing, and the time interval Ts is constant. The rotational position pulse count values at each sampling time S0, S1, S2,... Are denoted by P0, P1, P2,.
Also, the rotation position pulse generation time immediately before each rotation position data sampling is denoted by t0, t1, t2,.
The rotational position pulse generation times t0, t1, t2,.
Enters the time data latch register 10.

The rotation speed N1 that can be detected at the sampling timing S1 is N1 = (P1-P0) / (t1-t0), and the rotation speed N2 that can be detected at the sampling timing S2 is N2 = (P2-P1) / (t2). −t1). That is, assuming that the increment values of the rotation position data and the time data of the rotation position pulse generation from the previous rotation position data sampling to the current rotation position data sampling time are ΔP and Δt, respectively, the rotation speed Ndet
Is represented by Ndet = ΔP / Δt. As is clear from this equation, the resolution of the rotation speed N can be increased by setting the resolution of Δt higher than the rotation position data sampling cycle.

Next, the serial signal will be described with reference to FIG. FIG. 4 is an example of a serial signal data frame transmitted from the encoder to the rotation speed control device at one position sampling timing. In this frame, a start bit or a communication synchronization bit is first, followed by header data and rotation position data. Then, the time data of the rotation position pulse generation follows, and finally becomes the data for checking. This communication method is a commonly used communication method and will not be described here. As for the number of bits of the data frame, an appropriate number of bits is selected according to the number of rotation position pulses per rotation, the clock frequency of time counting, and the like.

Next, a process performed by the speed detector 25 of the speed control device 20 on the serial signal output from the encoder 24 will be described with reference to FIG. The processing performed here is basically the calculation of the speed detection value Ndet. First, the serial signal processing unit 61 checks the configuration and data of the serial signal frame, and decomposes it into position pulse number data P and pulse generation time data t. The rotational position data P and the rotational position pulse generation time data t obtained here are sent to the differentiators 62 and 63, respectively, and the difference values ΔP and ΔP at each sampling timing are obtained.
t. This is divided by the divider 64,
The rotation speed detection value Ndet is obtained.

According to the embodiment of the present invention, by using the serial output encoder for the rotation speed control, even when the sampling period of the rotation position data of the encoder is short or the number of rotation position pulses per one rotation of the encoder is small, Thus, a rotational speed detection value having a sufficient resolution can be obtained. As a result, a motor rotation speed control device having high accuracy and high speed control response can be realized.

[0026]

According to the present invention, it is possible to obtain an encoder and a motor drive device having a simple structure, capable of obtaining a high-precision rotational speed detection value and having high speed control response.

[Brief description of the drawings]

FIG. 1 is a block diagram of a serial encoder of the present invention.

FIG. 2 is a block diagram of a motor driving device according to the present invention.

FIG. 3 is an explanatory diagram showing a temporal change of a position pulse count value in the present invention.

FIG. 4 is a configuration diagram of a serial output frame according to the present invention.

FIG. 5 is a block diagram of a speed detector in the speed control device according to the present invention.

FIG. 6 is a block diagram of a conventional serial output encoder.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotating plate with a slit, 2 ... LED, 3 ... Slit transmission signal detector, 4 ... Rotation position pulse counter, 5 ... Rotation position data register, 6 ... Clock generator, 7 ... Periodic counter, 8 ... Time counter, 9 position pulse generation time register, 10 time data register, 11 serial data converter, 20 speed controller, 21 speed controller, 22 current amplifier, 23 motor, 24 encoder, 25 speed detection Device, 26... Speed difference subtractor, 61
... Serial signal processor, 61 ... Position pulse number differencer, 6
3 ... pulse generation time differencer, 64 ... divider.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Sumio Kobayashi 7-1-1, Higashi Narashino, Narashino-shi, Chiba F-term (reference) 2F077 AA25 CC02 NN02 NN30 PP19 TT78 2F103 BA37 CA02 DA01 EA12 EB06 EB33 ED21 FA00

Claims (6)

[Claims] A rotation position pulse generating means for detecting rotation of a motor and generating a rotation position pulse signal, and a rotation position for generating rotation position data from the rotation position pulse signal based on a timing of a sampling signal of a predetermined cycle. Data generating means, time data generating means for generating time data from a clock signal based on the timing of the sampling signal, and a serial data converter for converting the rotational position data and the time data into a serial signal and outputting the serial signal. An encoder characterized by comprising: 2. A rotational position pulse generating means for detecting a rotation of a motor to generate a rotational position pulse signal, and a rotational position for generating rotational position data from the rotational position pulse signal based on a timing of a sampling signal of a predetermined cycle. Data generating means, time data generating means for generating time data from a clock signal based on the timing of the sampling signal, and a serial data converter for converting the rotational position data and the time data into a serial signal and outputting the serial signal. An encoder, wherein the cycle of the clock signal is shorter than the cycle of the sampling signal. 3. A rotation position pulse generating means for detecting rotation of a motor to generate a rotation position pulse signal, and counting the rotation position pulse signal to generate a rotation position pulse count value. A rotation position data generating means for generating rotation position data by latching the clock signal with a sampling signal of a predetermined period, generating a time count value by counting clock signal pulses, and latching the time count value with the sampling signal of the predetermined period. An encoder comprising: time data generating means for generating time data; and a serial data converter for converting the rotational position data and the time data into serial signals and outputting the serial signals. 4. A clock generator for generating a clock signal having a predetermined period, a constant period counter for generating a sampling signal having a predetermined period longer than the clock signal from the clock signal, and a rotation position pulse signal detecting rotation of the motor. A rotation position pulse generating means for generating a rotation position pulse count value by counting the rotation position pulse signal;
A rotation position data generating means for generating rotation position data by latching the rotation position pulse count value with the sampling signal, and generating a time count value by counting clock signal pulses of the clock generator; And a serial data converter that converts the rotational position data and the time data into a serial signal and outputs the serial signal. Characterized encoder. 5. A motor according to claim 1, further comprising a motor, an encoder, and a speed controller, wherein said encoder detects rotation of said motor and generates a rotation position pulse signal; Rotation position data generation means for generating rotation position data based on the timing of a sampling signal, time data generation means for generating time data based on the timing of the sampling signal from a clock signal, the rotation position data and the time data And a serial data converter that converts the serial signal into a serial signal and outputs the speed signal. The speed control device detects a serial signal output from the encoder and outputs a speed detection value. Speed control means for controlling the speed by comparing the speed detection value output from the heater with the speed command value Motor drive device, characterized in that. 6. A motor, an encoder, and a speed controller, wherein the encoder detects rotation of the motor to generate a rotation position pulse signal, and counts the rotation position pulse signal. A rotational position data generating means for generating a rotational position pulse count value, latching the rotational position pulse count value with a sampling signal of a predetermined period to generate rotational position data, and generating a time count value by counting clock signal pulses; A time counter that latches the time count value with the rotation position pulse signal to generate a rotation position pulse generation time value, and latches the rotation position pulse generation time value with the sampling signal of the predetermined cycle to obtain time data. Time data generating means for generating, and converting the rotational position data and the time data into a serial signal. A speed detector that outputs a speed detection value by detecting a serial signal output from the encoder; and a speed detector that outputs a speed detection value from the speed detector. Speed control means for comparing the speed and the speed command value to control the speed, wherein the speed detector processes the serial signal output from the encoder to convert the position pulse number data and the pulse generation time data into position pulse number data and pulse generation time data. Serial signal processing means for separately outputting, position pulse number difference means for calculating the difference between the position pulse number data at each sampling timing, and pulse generation time for calculating the difference between the pulse generation time data at each sampling timing A difference means for dividing a difference value of the position pulse number difference device by a difference value of the pulse generation time difference device to output a speed detection value; Motor driving apparatus characterized by a means.