JPH07218289A - Encoder system - Google Patents

Abstract

PURPOSE:To ensure the resolution for a small angle and the transmission rate when rotary speed increases by setting a resolution with a specific magnification when a pulse signal from a signal converter exceeds the allowable maximum frequency of a signal reception circuit or a transmission path. CONSTITUTION:A phase-A pulse signal proportional to the angle of rotation of a detection axis 41 and a phase-B pulse signal with a phase difference as compared with the phase-A pulse signal are compressed (divided) by a demagnification factor specified by a resolution setting signal and are transmitted to a reception circuit 51 of a controller 50. At this time, a frequency detection part 52 measures the number of pulses per hour of both pulse signals, transmits a resolution-setting signal with a specific magnification from a resolution switching part 53 to a conversion part 43 when the pulse signal reaches the receivable maximum frequency of the circuit 51 or the transmittable maximum frequency of a transmission path 30, outputs the pulse signal without dividing (compressing) it when the rotary speed of the axis 41 is slow for achieving a fine positioning, and does not divide the pulse signal when the rotary speed is fast, thus increasing the rotary speed without considering the capacity of a circuit 31 or the transmission path 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder directly connected to a rotary shaft of a motor or the like and used for positioning, and more particularly to an improvement in which resolution and rotational angular velocity are linked.

[0002]

2. Description of the Related Art The applicant of the present invention has proposed an encoder for detecting the rotational angular velocity of a rotary shaft in Japanese Patent Laid-Open No. 2-242116. FIG. 5 is a configuration block diagram of a conventional XY table device. In the figure, the XY table device 10 is
XY to move the work to the position that is positioned in the plane
It has a table 11 and such an XY table 1
1 includes an XY recorder and a component mounter for mounting electronic components on a printed circuit board. X of XY table 11
For the axis, the X-axis motor 12 operates according to the X-axis command value input via the driver 14, and the encoder 13
As a result, A-phase and B-phase signals including information on the X-axis movement amount and movement direction are output. Regarding the Y-axis of the XY table 11, the Y-axis motor 15 operates according to the Y-axis command value input via the driver 17, and the encoder 16 controls the A-phase and the B-phase of the A-phase and B-phase including the information of the Y-axis movement amount and the movement direction. The signal is output.

The two-axis controller 20 outputs a signal for controlling the XY table device 10, and has an X-axis DA converter 22 for sending the X-axis command value to the driver 14, and an X-axis A-phase signal sent from the encoder 13. It has a direction detection X-axis counter 21 for receiving a B-phase signal. Further, it has a Y-axis DA converter 24 which sends the Y-axis command value to the driver 17, and a direction detection Y-axis counter 23 which receives the Y-axis A-phase / B-phase signals sent from the encoder 16. μ processor 25
Sends an X-axis / Y-axis command value to the X-axis DA converter 22 and the Y-axis DA converter 24 as a positioning signal for the XY table 11, and as a feedback signal, the direction detection X-axis counter 2
1 and the direction detection Y-axis counter 23 receives information about the moving direction and the moving amount of each of the X-axis and the Y-axis, and performs so-called servo control.

A signal transmission path 30 is connected between the XY table device 10 and the two-axis controller 20, and an X-axis command value, an X-axis A-phase / B-phase signal, a Y-axis command value, and a Y-axis A. Phase and B phase signals are being sent and received.

FIG. 6 is a waveform diagram of X-axis / Y-axis A-phase / B-phase signals sent from the encoder. Here, the case where the encoder rotates clockwise CW is shown. Since the phase of the B-phase signal is 90 degrees behind that of the A-phase signal, it is possible to determine whether the rotation direction is CW or CCW.

[0006]

The resolution of the encoder is defined by the number of A-phase / B-phase output pulses per rotation. The resolution of the encoder mounted on the XY table device 10 is the minimum resolution required for the XY table 11, the maximum moving speed, the maximum frequency of the encoder A-phase / B-phase output signal in the transmission path 30, and the biaxial controller 20. It is determined in consideration of the maximum frequency that can be received on the side.

However, when the XY table 11 requires a very high resolution, the maximum frequency on the XY table 11 becomes a bottleneck due to the maximum frequency in the transmission path and the maximum frequency that can be received by the two-axis controller 20. There is a problem that the moving speed becomes slow. The present invention solves the above-mentioned problems, and an object of the present invention is to provide an encoder system in which the maximum movement speed on the XY table is not limited even when the XY table requires very high resolution.

[0008]

FIG. 1 is a block diagram showing the configuration of the present invention for achieving the above object. In the figure, the encoder system outputs an A / B phase signal that outputs a phase A pulse signal that is proportional to the rotation angle of the detection shaft 41 and a phase B pulse signal that has a phase difference of approximately 90 degrees with respect to this phase A pulse signal. An encoder 40 having a generator 42, a signal converter 43 for compressing the A-phase pulse signal and the B-phase pulse signal output from the A / B-phase signal generator by a magnification N designated by a resolution setting signal, and this signal A transmission line 30 for transmitting the converted A ′ phase pulse signal and B ′ phase pulse signal output from the converter, and a receiving circuit 51 connected to this transmission line.
And a frequency detecting section 52 for measuring the number of pulses per unit time of the A ′ phase pulse signal and the B ′ phase pulse signal sent from this transmission line, and the pulse frequency detected by this frequency detecting section is the receiving circuit concerned. When the maximum frequency that can be received or the maximum frequency that can be transmitted by the transmission path is reached, the controller 50 is provided with a resolution switching unit 53 that sends the resolution setting signal of a predetermined magnification N to the signal converter. There is.

[0009]

The encoder includes an A / B phase signal generator having a resolution for minute angles, and the frequency of the A phase pulse signal and the B phase pulse signal becomes excessive as the rotation speed increases, so that the reception circuit receives signals. Since the pulse transmission through the transmission line may be hindered, the signal transmission device has a signal converter that reduces the frequency of the pulse signal by roughening the resolution with the resolution setting signal. The controller knows the maximum frequency of the receiving circuit and transmission line, and if the frequency detector detects that the pulse signal output from the signal converter exceeds this maximum frequency, the resolution switching unit sends the resolution setting signal. Output. As a result, both the resolution for a minute angle and the securing of the transmission speed when the rotation speed increases are compatible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 2
Is a configuration block diagram showing an embodiment of the present invention, and here, for simplification of description, only one axis is targeted. In the figure, the X-axis moving device 60 has an X-axis moving mechanism 61 for moving the work in the X-axis direction. The motor 62 receives power supply from the driver 65, transmits power to the X-axis moving mechanism 61, and the encoder 63 detects the amount of rotation of the X-axis. Here, the encoder 63 adopts an increment type, and is directly connected to the rotation shaft of the motor 62 and also has a built-in frequency divider having a function equivalent to that of the signal converter 43 described above. Limit switch 6
Reference numeral 4 is provided at one end of the movable range of the X-axis moving mechanism 61 and sends a signal corresponding to the origin serving as a reference for position detection of the encoder 63 to the 1-axis controller 70 side.

The 1-axis controller 70 is provided with a direction detection X-axis counter 71 corresponding to the above-mentioned receiving circuit 51, and the A'phase pulse signal and the B'phase pulse signal whose frequency has been divided by the encoder 63 are transmitted through the transmission line. It is sent via 30.
The direction detection X-axis counter 71 extracts the moving direction and position information from the input A′-phase pulse signal and B′-phase pulse signal and sends them to the μ processor 72. The μ processor 72 performs various calculations according to the programs stored in the ROM 73 and the data stored in the RAM.

Here, the μ processor 72 detects the direction detection X-axis of the A ′ phase pulse signal and the B ′ phase pulse signal based on the X-axis speed information sent from the direction detection X-axis counter 71.
It is determined whether the maximum frequency that can be counted by the axis counter 71 or the maximum frequency that can be transmitted by the transmission line 30 is exceeded. When it is determined that the values are exceeded, the resolution setting signal 0 and the resolution setting signal 1 are set and the frequency divider of the encoder 63 is operated. The frequency division ratio of this frequency divider can be selected to be a power of 2 such as (1/2, 1/4, 1/8, 1/16).

Further, the μ processor 72, based on the X-axis speed information sent from the direction detection X-axis counter 71, sends a minute pulse signal having a smaller frequency division ratio to the 1-axis controller 70 due to a decrease in speed. When transmission becomes possible, the resolution setting signal 0 and the resolution setting signal 1 are set and the frequency divider of the encoder 63 is stopped. Then, the A-phase pulse signal and the B-phase pulse signal that have not been frequency-divided are transmitted to the uniaxial controller 70 via the transmission path 30, so that a minute position on the X axis can be measured.

Further, the μ processor 72 sends a synchronous clock to the encoder 63 to facilitate counting by the direction detecting X-axis counter 71. In addition, the driver 6
It is sent to 5 and the moving speed is also set.

The operation of the apparatus thus configured will be described. FIG. 3 is a waveform diagram for explaining the operation of the device of FIG. 2 at the time of startup. (A) is a clock signal, (B) is a resolution setting signal 1, (C) is a resolution setting signal 0, and (D) is a frequency dividing signal. (E) represents a B'phase signal output from an encoder with a built-in device. Here, 0 and 1 of the resolution setting signal are sequentially validated as the moving speed increases.

FIG. 4 is a diagram for explaining changes in the output frequency of the encoder from the start of movement to the end of movement. When the power supplies of the X-axis moving device 60 and the 1-axis controller 70 are turned on, first, in order to detect the origin serving as the reference of the position information,
The 1-axis controller 70 moves the X-axis in the direction of the limit switch 64. Then, when the limit switch 64 is turned on as an interrupt signal, the μ processor 7
2 performs detection. When the origin detection interrupt occurs, the μ processor 72 immediately stops moving the X axis, resets position information inside the μ processor 72, and sets this position as a reference.

Next, the case where the μ processor 72 moves the X axis to a certain position according to the program written in the ROM 73 will be described. The μ processor 72 performs a servo calculation using the set target position, the current position information and the current speed information obtained from the output signal of the encoder 63, and outputs a speed command value to the driver 65 via a DA converter (not shown). Output.

The motor 62 receives the speed command value via the driver 65 and moves the X axis. Since the target position is often away from the current position, the moving speed of the X axis gradually increases.
The frequencies of the phase pulse signal and the B phase pulse signal also increase (τ1). Here, if the encoder 63 having a very high resolution is used, the command value is continuously output to the driver 65, so that the maximum frequency that can be received by the uniaxial controller 70 side is exceeded.

Therefore, on the one-axis controller 70 side, when the output signal from the encoder 63 approaches the maximum receivable frequency, the resolution setting signal 0 and the resolution setting signal 1 are set in the frequency divider to set the resolution of the encoder 63. At the same time as setting to 1/2, the current position information and the current speed information obtained from the output signal of the encoder 63 are doubled, and servo calculation is performed based on the interpreted data (τ2). The output signal of the encoder 63 is 1/0 depending on the resolution setting 1 signal.
Since the number of pulses is 2, the 1-axis controller 70 side can continue to receive.

When the workpiece approaches the target position with the passage of time, the speed command value to the driver 65 also decreases, and correspondingly, the A-phase pulse signal and the B-phase pulse from the encoder 63 The frequency of the signal will also drop.
When the output signal from the encoder 63 reaches 1/2 of the maximum receivable frequency, the resolution setting signal 0 and the resolution setting signal 1 are set in the frequency divider and the resolution of the encoder 63 is returned to the original value (τ3). Then, on the one-axis controller 70 side, the current position information and the current speed information obtained from the output signal of the encoder 63 are used as they are, and servo calculation is performed based on this data. The output signal from the encoder 63 returns to the original resolution due to the resolution setting signal 0 and the resolution setting signal 1, so the frequency of the pulse is doubled and fine positioning becomes possible.

[0021]

As described above, according to the present invention,
When the rotation speed of the shaft is slow, the A-phase / B-phase pulse signal of the encoder 40 is output to the controller side without frequency division, so that fine positioning is possible. On the other hand, when the rotation speed of the shaft is fast, the A-phase / B-phase pulse signal of the encoder 40 is divided and output to the controller side, so that the ability of the receiving circuit or the transmission path 30 for receiving the pulse signal is not taken into consideration. , The rotation speed of the shaft can be increased. Therefore,
Even when the XY table requires a very high resolution, the maximum moving speed on the XY table is not limited, and an XY table device capable of quick and accurate positioning can be realized.
There is an effect that it is preferable as an encoder.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing a configuration of the present invention.

FIG. 2 is a configuration block diagram showing an embodiment of the present invention.

FIG. 3 is a waveform diagram illustrating the operation of the device of FIG. 2 at startup.

FIG. 4 is a diagram for explaining changes in the output frequency of the encoder from the start of movement to the end of movement.

FIG. 5 is a configuration block diagram of a conventional XY table device.

[Fig. 6] A-phase / B of X-axis and Y-axis sent from the encoder
It is a wave form diagram of a phase signal.

[Explanation of symbols]

 30 transmission line 40 encoder 42 A / B phase signal generator 43 signal converter 50 controller 51 receiving circuit 52 frequency detecting unit 53 resolution switching unit

Claims (1)

[Claims] 1. An A / B phase signal which outputs an A phase pulse signal proportional to a rotation angle of a detection shaft (41) and a B phase pulse signal having a phase difference of approximately 90 degrees with respect to the A phase pulse signal. An encoder having a generator (42) and a signal converter (43) for compressing the A-phase pulse signal and the B-phase pulse signal output from the A / B-phase signal generator at a magnification N designated by a resolution setting signal ( 40), a transmission line (30) for transmitting the converted A ′ phase pulse signal and B ′ phase pulse signal output from this signal converter, and a receiving circuit (51) connected to this transmission line, A frequency detector (5) for measuring the number of pulses per unit time of the A'phase pulse signal and the B'phase pulse signal sent from the transmission line.
2) and when the pulse frequency detected by this frequency detection unit reaches the maximum frequency that can be received by the receiving circuit or the maximum frequency that can be transmitted by the transmission line, the resolution setting signal with a predetermined magnification N is set. An encoder system comprising: a controller (50) having a resolution switching unit (53) for sending to a signal converter.