JP4214590B2 - Rotary encoder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary encoder for detecting the rotational position of a rotating body, and more particularly to an incremental encoder used by being incorporated in a three-phase AC servomotor.
[0002]
[Prior art]
Servo motors used for driving various machines include DC servo motors with brushes and AC servo motors without brushes. In recent years, demand for AC servo motors has increased due to the ease of motor maintenance.
[0003]
There are various types of servo system position detectors. In recent years, rotary encoders have become widespread as position detectors incorporated in servo motors. There are an incremental type and an absolute type as an encoder incorporated in an AC servo motor. The incremental type is attached to an AC servo motor of various machines and widely used, and occupies the mainstream as an AC servo encoder.
[0004]
On the other hand, the absolute type is an encoder that can determine the absolute position within one rotation and does not require an origin return operation, and is therefore widely used in robot servo motors such as articulated robots.
[0005]
A conventional incremental encoder will be described below. FIG. 10 shows the configuration of a conventional incremental encoder, in which 91 is a light emitting element, 92 is a rotating slit plate, 93 is a light receiving element, 94 is a waveform shaping circuit, and 95 is a signal transmission circuit.
[0006]
As shown in FIG. 11, the output signals are A and B phase signals having a phase difference of 90 degrees so that the rotation direction can be discriminated, an origin reference Z signal for one rotation and one pulse, and phase excitation switching of an AC servo motor. Are provided with commutation signals CS1, CS2 and CS3.
[0007]
[Problems to be solved by the invention]
However, the conventional configuration has a problem in that the number of output signals is large and the number of wirings is large, resulting in poor mass productivity, and erroneous wiring to devices and disconnection of signal lines are likely to occur.
[0008]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described conventional problems, and to provide an incremental encoder that reduces the number of output signals of an encoder, has high productivity and high reliability.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an A and B phase incremental signal having a phase difference of 90 degrees from each other, a reference signal Z indicating the origin during one rotation, and a phase excitation switching signal for a three-phase AC servomotor. (Commutation signal) Original signal output unit that outputs CS1, CS2, and CS3 phases, power supply ON / OFF detection circuit that detects the on / off state of the encoder main power supply, and count-up pulses based on the phases of A and B2 phases And a direction discriminating circuit that outputs a down pulse, a first up / down counter and a second up / down counter that can preload count initial data and count the output pulses of the direction discriminating circuit, and A and B two-phases after power ON Outputs initial data to be preloaded to the first up / down counter and the second up / down counter according to the level. A first initial value detection circuit; a second initial value detection circuit that outputs offset data to be preloaded to the first up / down counter or the second up / down counter by the reference signal Z and a preload flag indicating completion of a preload operation; Receiving an external data request signal, and simultaneously holding the CS1, CS2 and CS3 phases from the original signal output unit, the data from the first up / down counter and the second up / down counter, and a preload flag; And a data transmission / reception circuit for converting to serial data and outputting the serial data.
[0010]
By the above means, the encoder output signals A, B, Z, CS1, CS2, CS3 can be transmitted as serial data in one line, so the number of encoder output signals can be greatly reduced, including incorporation into equipment. A highly reliable rotary encoder with excellent mass productivity can be obtained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above-described problems, the present invention provides an A and B phase incremental signal having a phase difference of 90 degrees, a reference signal Z indicating the origin during one rotation, and a phase excitation switching signal ( Commutation signal) an original signal output unit that outputs CS1, CS2, and CS3 phases, a power ON / OFF detection circuit that detects the ON / OFF state of the encoder main power supply, a count-up pulse based on the phases of A and B2, and Direction discriminating circuit that outputs a down pulse, first up / down counter and second up / down counter that can preload count initial data and count the output pulse of the direction discriminating circuit, and levels of A and B phases after power ON To output initial data to be preloaded to the first up / down counter and the second up / down counter. A first initial value detection circuit; a second initial value detection circuit for outputting offset data to be preloaded to the first up / down counter or the second up / down counter by the reference signal Z; and a preload flag indicating completion of the preload operation; The data request signal from the first signal is received, and simultaneously with the reception of the request signal, the CS1, CS2 and CS3 phases from the original signal output unit, the data from the first up / down counter and the second up / down counter, the preload flag are held, and the serial The rotary encoder includes a data transmission / reception circuit that converts data into data and outputs the data.
[0012]
Further, the data from the first initial value detection circuit is preloaded to the first up / down counter and the second up / down counter based on the power ON information from the power ON / OFF detection circuit, and the second initial value is determined based on the first reference signal Z. This is a rotary encoder that preloads 0 (zero) as offset data output from the detection circuit to the second up / down counter.
[0013]
Further, the data from the first initial value detection circuit is preloaded to the first up / down counter and the second up / down counter based on the power ON information from the power ON / OFF detection circuit, and the second initial value is determined based on the first reference signal Z. This is a rotary encoder that preloads the second up / down counter with a value at which the most significant bit of the counter becomes “1” as the offset data output from the detection circuit at a resolution higher than the resolution per one rotation of the encoder.
[0014]
Further, based on the power ON information from the power ON / OFF detection circuit, the data from the first initial value detection circuit is supplied to the first up / down counter, and the data from the first initial value detection circuit is equal to or higher than the resolution per encoder rotation. Rotary encoder that preloads the second up / down counter with data obtained by adding the values of 0 and preloads 0 (zero) to the second up / down counter as offset data output from the second initial value detection circuit by the first reference signal Z It is.
[0015]
Thus, the number of encoder output signals can be greatly reduced.
Further, by comparing data between the first up / down counter and the second up / down counter, the amount of movement from the time of power-on to the reference signal Z and the amount of movement from the reference signal Z can be obtained from the data of the second up / down counter. .
[0016]
In addition, by observing the data change of the second up / down counter, when the first reference signal Z is detected, and when the power is turned on by comparing the first up / down counter with the data excluding the most significant bit of the second up / down counter To the reference signal Z and the movement amount from the reference signal Z can be obtained from data excluding the most significant bit of the second up / down counter.
[0017]
Further, by observing the data change of the second up / down counter, it is possible to obtain the amount of movement from the reference signal Z from the presence / absence of detection of the first reference signal Z and the data of the second up / down counter.
[0018]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0019]
FIG. 1 is a configuration diagram of a rotary encoder in an embodiment of the present invention. In FIG. 1, 11 is an original signal output unit, 12 is a direction discrimination circuit, 13 is a first initial value detection circuit, 14 is a second initial value detection circuit, 15 is an n-bit first up / down counter, and 16 is an m-bit counter. A second up / down counter, 17 is a data transmission / reception circuit, 18 is a power ON / OFF detection circuit, 19 is a bidirectional bus, 20 is a digital adder, and 21 is an AND gate element.
[0020]
The original signal output unit 11 includes the light emitting element 91, the rotary slit plate 92, the light receiving element 93, and the waveform shaping circuit 94 shown in FIG. 10 as in the conventional incremental encoder. A typical example of the output signal is as shown in FIG. An incremental signal and a three-phase excitation switching commutation signal are output.
[0021]
FIG. 2 shows an example of operation waveforms of the direction discriminating circuit 12. When the A phase is ahead of the B phase, a down pulse is output, and when the A phase is behind the B phase, an up pulse is output. The up pulse and the down pulse are input to the up / down counters 15 and 16, and the count data is changed by counting the pulses.
[0022]
3A shows an example of the operation waveform of the first initial value detection circuit, and FIG. 3B shows an example of the circuit thereof. The A and B phase signals “H” and “L” are used to generate a 2-bit initial value D1, D0 is output.
[0023]
FIG. 4A shows an example of operation waveforms of the first up / down counter and the second up / down counter. Here, an example of operation of the 16-bit counter is shown. This up / down counter is a pulse counter in which the data preload operation and the count operation are switched by the load signal output from the main power ON / OFF detection circuit 18 or the load signal output from the second initial value detection circuit.
[0024]
FIG. 4B is an example of the entire operation waveform of the first up / down counter and the second up / down counter.
[0025]
FIG. 5 is an example of operation waveforms of the second initial value detection circuit, and a load signal and a load flag are output when the reference signal Z is input for the first time after the power is turned on.
[0026]
The operation of the rotary encoder having the above configuration will be described below.
FIG. 6 shows an embodiment of the present invention, in which 0 (zero) is preloaded to the second up / down counter 16 when the first reference signal Z is detected after the power is turned on.
[0027]
First, when the main power is turned on, the A, B, Z, CS1, CS2, and CS3 signals are output from the original signal output unit 11. For example, when the main power supply is turned on in the A phase “H” and the B phase “L”, the first initial value detection circuit 13 sets D1 = 0 and D0 = 0, and the first signal is detected by the load signal from the power supply ON / OFF detection circuit 18. The up / down counter 15 is loaded with “0000” (hexadecimal number), and the second up / down counter 16 is a second initial value detection circuit determined based on the data from the first initial value detection circuit 13 and the operation mode. “0000” (hexadecimal number) obtained by adding the offset data “0000” from 14 to the digital adder 20 is preloaded as a count initial value.
[0028]
Next, when the shaft rotates to CCW, the up pulse from the direction discriminating circuit 12 is counted, and the count data of the up / down counter changes in the increasing direction.
[0029]
Further, when the reference signal Z phase is detected for the first time after the shaft rotates to CCW and the power is turned on, 0 (zero) is output as offset data by the second initial value detection circuit 14 based on the operation mode, and the digital adder 20 outputs the first initial value. The offset data “0000” is added to the data from the value detection circuit and becomes the load data of the second up / down counter 16. At the same time, the load data is loaded into the second up / down counter 16 by the load signal from the second initial value detection circuit 14 via the AND gate element 21, and the counter once counts to "0000" (hexadecimal number) and then performs the count operation. continue.
[0030]
Here, the data in the encoder is communicated with a host device such as a servo driver via the data transmission / reception circuit 17 and the bidirectional bus 19, and the data request signal is sent to the servo driver according to the timing when the encoder data is required. The encoder side receives this request signal, and simultaneously holds the data in the encoder and converts it into serial data, and then outputs the data to the servo driver side.
[0031]
In FIG. 6, a, b, c, d, and e are timing pulse generation points when data in the encoder is output to the servo driver side by data communication. At this timing, the first up / down counter 15 and the second up / down counter The CS1, CS2, and CS3 signals from the counter 16 and the original signal output unit 11 are held in the data transmission / reception circuit 17 and converted into serial data, and then output as data.
[0032]
On the servo driver side which is the host device, after receiving the data from the encoder, the received data is restored to the A, B, and Z phase signals in order to output position information to the NC device or the like which is the host device. What is very important here is how to restore the Z-phase signal at an accurate position.
[0033]
In FIG. 6, when focusing on only the first up / down counter and viewing the count data for each timing pulse, the Z phase passes between the points b and c, so in this case the Z phase must be accurately restored. Is impossible. Here, when attention is paid to the data together with the second up / down counter, the timing pulse is calculated from the change amount x of the first up / down counter and the change amount y from “0” of the second up / down counter from the point b to the point c. The Z-phase position of the servo driver can be discriminated, and the servo driver side restores how many pulses of the A and B phases between points c and d from the received data, and at which position of the restored pulse the Z phase is restored. You can easily do better.
[0034]
FIG. 7 shows an embodiment of the present invention. When the first reference signal Z is detected after the power is turned on, the second up / down counter 16 has a value equal to or higher than the resolution of one rotation of the encoder and the most significant bit of the counter is “1”. When the encoder resolution is 16 bits, for example, a value obtained by adding 10000 (hexadecimal number) is preloaded, and the basic operation of the up / down counter is the same as in FIG.
[0035]
In this case, the servo driver side always observes the data change of the second up / down counter 16 and can detect the presence or absence of the first Z phase detection by detecting the data change of one rotation resolution or more, thereby reducing the preload flag. it can.
[0036]
In the Z-phase restoration, similarly to FIG. 6, the change amount x of the first up / down counter 15 and the change amount of the lower 16 bits excluding the most significant bit of the data of the second up / down counter 16 from the point b to the point c. That is, information for restoring the Z phase can be obtained from the change amount y.
[0037]
FIG. 8 is an operation diagram when the counter operation in FIG. 7 is viewed globally. When the resolution of one rotation of the encoder is 16 bits, the first up / down counter 15 responds to the rotation amount from “0000” after the power is turned on. Thus, the second up / down counter 16 performs a cyclic operation between “10000” and “1FFFF” after the first detection of the reference signal Z. In this case, after the first Z-phase detection, “0000” of the second up / down counter can be defined as the Z-phase position data (absolute position), and the Z-phase can be easily restored on the servo driver side.
[0038]
FIG. 9 shows an embodiment of the present invention. As the initial count value of the second up / down counter 16 after the power is turned on, a value equal to or higher than the resolution of one rotation of the encoder, for example, 10000 (hexadecimal number) when the encoder resolution is 16 bits. Is the initial value, and “0” is loaded into the second up / down counter 16 by the first reference signal Z, and the basic operation of the up / down counter is the same as in FIG. 6 and FIG.
[0039]
In this case as well, the servo driver side can always observe the data change of the second up / down counter 16 and detect the data change of one rotation resolution or more to determine whether or not the first Z phase is detected, and the preload flag is set. Can be reduced.
[0040]
Further, in the Z-phase restoration, in order to restore the Z-phase, the change amount x of the first up / down counter 15 and the change amount y of the second up / down counter 16 from “0” from the point b to the point c are the same as in FIG. Information can be obtained.
[0041]
As described above, the combination of two up / down counters capable of data preloading and the data loading operation, and outputting the data in the encoder as serial data greatly reduces the number of signal lines output from the encoder and at the same time from the encoder. A, B, and Z phases can be easily restored based on serial data.
[0042]
【The invention's effect】
As is apparent from the above embodiments, the present invention reduces the number of signal lines, which conventionally required 14 lines, to 4 by transmitting A, B, Z, CS1, CS2 and CS3 signals as serial data. Therefore, it is possible to realize a rotary encoder with high productivity and high reliability.
[0043]
Also, bidirectional data transmission makes it possible to request encoder data and output data at the optimal timing for servo control.
[0044]
Further, by combining the two up / down counters and the data load, it is possible to detect the presence or absence of the first reference signal Z and to accurately detect the amount of movement from the reference signal Z. Based on these information, A, The restoration of the B and Z signals can be facilitated.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a rotary encoder according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of operation waveforms of a direction discriminating circuit according to an embodiment of the present invention. FIG. 4B is a diagram illustrating operation waveforms of the detection circuit. FIG. 4A is a diagram illustrating detailed operation of the up / down counter according to the embodiment of the present invention. FIG. 4B is a diagram illustrating the entire operation of the up / down counter. FIG. 5 is a diagram illustrating operation waveforms of the second initial value detection circuit according to the embodiment of the present invention. FIG. 6 is a diagram illustrating operations of the first up / down counter and the second up / down counter according to the embodiment of the present invention. FIG. 8 is a diagram illustrating the operation of the first up / down counter and the second up / down counter according to the embodiment of the present invention. FIG. 8 is a diagram illustrating the overall operation of the first up / down counter according to the embodiment of the present invention. 9. First embodiment of the present invention Operation diagram-down counter and second up-down counter 10 shows the conventional rotary encoder configuration diagram [11] Conventional rotary encoder operation waveform diagram EXPLANATION OF REFERENCE NUMERALS
11 Original Signal Output Unit 12 Direction Discriminating Circuit 13 First Initial Value Detection Circuit 14 Second Initial Value Detection Circuit 15 First Up / Down Counter 16 Second Up / Down Counter 17 Data Transmission / Reception Circuit 18 Power ON / OFF Detection Circuit 19 Bidirectional Bus 20 Digital adder 21 AND gate element 91 Light emitting element 92 Rotating slit plate 93 Light receiving element 94 Waveform shaping circuit 95 Signal transmission circuit

Claims (4)

Incremental signals of phases A and B having a phase difference of 90 degrees from each other, a reference signal Z indicating the origin during one rotation, a phase excitation switching signal (commutation signal) CS1, CS2, CS3 of a three-phase AC servomotor An original signal output unit that outputs an ON / OFF detection circuit that detects an ON / OFF state of an encoder main power supply, a direction discriminating circuit that outputs a count up pulse and a down pulse depending on the phases of the A and B phases, and a count A first up / down counter and a second up / down counter for preloading initial data and counting the output pulses of the direction discriminating circuit, and the first up / down counter and the second up / down counter according to the levels of the A and B phases after the power is turned on. a first initial value detecting circuit for outputting the initial data to be preloaded into the down counter, before after power oN Reference signal Z is first "L" level to "H" to preload the offset data and offset data preload changes in the level and indicating the origin in one rotation to the second up-down counter to the second up-down counter A second initial value detection circuit for outputting a load signal and a preload flag indicating completion of the preload operation, and a CS1, CS2, CS3 phase from the original signal output unit upon receiving the data request signal from the outside and simultaneously receiving the request signal And a data transmission / reception circuit that holds data from the first up / down counter and the second up / down counter and a preload flag, converts the data into serial data, and outputs the serial data. The power-ON information from the power ON / OFF detecting circuit, the data from the first initial value detecting circuit to preload the first up-down counter and second up-down counter, after power ON reference signal Z is first "L" level 2. A rotary encoder according to claim 1, wherein when the origin changes during one rotation by changing from "H" to "H" level, 0 (zero) is preloaded to the second up / down counter as offset data output from the second initial value detection circuit. . The power-ON information from the power ON / OFF detecting circuit, the data from the first initial value detecting circuit to preload the first up-down counter and second up-down counter, after power ON reference signal Z is first "L" level When the origin from one rotation is indicated by changing from "H" level to "H" level, the value of the most significant bit of the counter is "1" as the offset data output from the second initial value detection circuit at a resolution higher than the resolution per encoder rotation The rotary encoder according to claim 1, wherein the second up / down counter is preloaded. Based on the power ON information from the power ON / OFF detection circuit, the data from the first initial value detection circuit is supplied to the first up / down counter, and the data from the first initial value detection circuit is a value greater than the resolution per encoder rotation. When the reference signal Z changes from “L” level to “H” level for the first time after turning on the power and indicates the origin during one rotation, the second initial value detection circuit The rotary encoder according to claim 1, wherein 0 (zero) is preloaded to the second up / down counter as output offset data.

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