JPH0242315A - Correcting circuit for one-rotation signal of position coder - Google Patents

Abstract

PURPOSE:To enable the position coder to output the output timing of a one- rotation signal at a constant rotation position by outputting a rotation position signal and the one-rotation signal. CONSTITUTION:The position coder outputs the rotation position signal AB corresponding to the rotation position of a rotary body and the one-rotation signal corresponding to the one rotation of the rotary body through operation of a one-rotation signal latch means 10. Further, a signal PZ for the one-rotation signal and signals PA, *PA, PB, and *PB for the rotation position signal are supplied from a sensor part. Those signals are outputs from magneto-resistance elements which are so installed as to generate mutually 180 deg.-out-of-phase outputs and also put the signals PA and PB 90 deg. out of phase with each other. Thus, the output timing of the one-rotation signal is obtained under nearly the same temperature conditions and power source voltage conditions.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a one-rotation signal correction circuit that corrects the timing of a one-rotation signal output from a position coder, and is particularly suitable for a position coder using a magnetoresistive element. This invention relates to a rotation signal correction circuit.

2. Description of the Related Art Encoders or position coders are used as position detection devices for numerically controlling each control axis in NC machine tools and the like. Although optical encoders and position coders are most widely used, position coders using magnetoresistive elements have recently come into use.

Since the rotating body side of this device is made of metal, it has the advantage of being strong against axial force, and is therefore suitable for detecting rotation of the spindle shaft, and is expected to become widespread in this field. The present invention refers to a one-rotation signal correction circuit particularly suitable for a position coder using such a magnetoresistive element.

[Conventional technology]

The position coder is used, for example, in a lathe or the like as a signal to keep the thread cutting start position constant. For example, when forming a spiral groove on the side surface of a cylindrical workpiece, processing is performed by rotating the workpiece and moving a tool in the axial direction in synchronization with the rotation of the workpiece. In this case, the machining cannot be completed with one movement of the tool, so the machining is divided into several parts, each time gradually moving the tip of the tool from the surface of the workpiece to the center. Processing can proceed. In such a case, the starting position of thread cutting must always be at a constant position with respect to the rotation of the shaft, and a position coder is used to obtain this timing.

FIG. 7 is a diagram for explaining the principle of a position coder using a magnetoresistive element. The shaft 90 whose rotation is measured has two disks 92 made of paramagnetic metal, for example steel;
94 are integrated. The disk 92 is for generating one rotational body number, and has a groove 93 at only one location as shown in the figure. On the other hand, the disk 94 is for generating a rotational position signal, and is provided with a large number of teeth, for example, 256 teeth, as shown in the figure. Although not shown, the sensor portion 80 is provided with a permanent magnet for forming a fixed magnetic field and magnetoresistive elements 82 and 84 for detecting the strength of the magnetic field.

For example, when a shaft 90 integrated with a spindle shaft of a lathe or the like rotates, the disks 92 and 94 also rotate together.

The strength of the magnetic field near the magnetoresistive elements 82, 84 changes depending on whether a paramagnetic metal is present nearby, and the resistance value of the magnetoresistive elements 82, 84 changes accordingly, and the value of the flowing current also changes. Therefore, as the shaft 90 rotates, a signal corresponding to one rotation of the shaft 90 (Z-phase signal) is obtained from the magnetoresistive element 82, and a signal corresponding to the rotational position (A-phase and B-phase signals) is obtained from the magnetoresistive element 84. is obtained.

FIG. 8 shows Z from the output signal of such a magnetoresistive element 82.
FIG. 3 is a diagram representing a method of obtaining phase signals; When the groove 93 approaches the magnetoresistive element 82 of FIG. 7, a signal having the waveform shown in column (1) of FIG. 8 is output from the magnetoresistive element 82. ■ The strength of this signal is the reference voltage. By comparing with , a digital signal as shown in column (2) can be obtained.

[Problem to be solved by the invention]

In the method shown in FIG. 8, either or both of the signal from the magnetoresistive element 82 and the reference voltage v0 fluctuate due to ambient temperature changes, power supply voltage fluctuations, etc., and the relative positional relationship changes. There is a problem that the timing at which the Z-phase signal is output may change due to the influence of noise or the like, which affects the processing accuracy.

Therefore, it is an object of the present invention to maintain the output timing of one rotating body number output from a position coder using a magnetoresistive element at a constant rotational position without being affected by ambient temperature, fluctuations in power supply voltage, noise, etc. An object of the present invention is to provide a signal correction circuit that corrects the output.

[Means to solve the problem]

FIG. 1 is a principle diagram of a one-rotation body position correction circuit of a position coder according to the present invention.

In the figure, a position coder 20 outputs a rotational position signal AB corresponding to the rotational position of the rotating body and one rotating body number Z corresponding to one rotation of the rotating body.

One rotational body number latch means 10, which is one of the features of the present invention, is used for one rotational body number while the rotational speed of the rotating body is above a predetermined speed, after the power of the device in which the correction circuit is incorporated is turned on. , which captures the output timing of the first revolution. Another feature of the counter means 30 is
Counting is permitted at the output timing of the 1st rotational body number captured by the 1st rotational body number latch means 10, and after that, the rotational position signal AB is counted and every time the rotational position signal AB is counted a predetermined number of times, a carry corresponding to the corrected 1st rotational body number is generated. Outputs signal Z'.

[Function] Due to the action of the one-rotation signal latch means 10, after the power is turned on,
Since the output timing of the one revolution signal Z is captured after the specified rotation is reached for the first time, it is possible to always capture the output timing of the one revolution signal (Z phase signal) under almost the same temperature and power supply voltage conditions. can. Thereafter, the counter means 12 receives the rotational position signal A regardless of the actual one-rotation signal Z.
B is counted and the carry signal Z' output at the time of count-up is used as the one-rotation signal after correction, so that a one-rotation signal that is unaffected by temperature changes, power supply voltage fluctuations, and noise can be obtained thereafter.

〔Example〕

FIG. 2 is a circuit block diagram representing one embodiment of the present invention.

In FIG. 2, a sensor part 80 (FIG. 7) supplies a signal PZ for the one revolution signal and signals PA, *PA, PB and *PB for the rotational position signal.

PA and *PA and PB and *PB are the outputs from magnetoresistive elements installed so that the phases are different from each other by 180@, and furthermore, they are output so that the phases of PA and PB are different from each other by 90''. Other inputs include signals from contact 61, which closes when the rotating body is stationary, and contact 62, which closes when the rotational speed of the rotating body reaches a predetermined value or higher. Supplied.

The one-rotation signal latch means 10 in FIG.
a contact receiver 15 that receives a signal from the system and converts it to a logic circuit level; an initial clear circuit 13 that outputs a clear signal when the system is powered on; and a Z phase latch circuit 14 that latches the Z phase. Inverting circuit 11 and AND
This is realized by a circuit consisting of gates 16 and 17.

The counter means 30 in FIG. 1 is an up/down counter 31.
This is realized by

Next, the operation of the circuit shown in FIG. 2 will be explained.

FIG. 3 is a timing chart illustrating the operation of the circuits around the second Z-matching circuit 14. The (1)th i represents the state of the power supply of the system in which this correction circuit is incorporated, and the (2)th! tjl represents the state of the initial clear signal a (FIG. 2) which is output for a certain period of time when the power is turned on. The third column is a signal obtained by receiving the signal from the contact 61 by the contact receiver 15 and converting it to a logic level.
This indicates that the rotating body starts rotating a certain time after the power is turned on. No. (4) IIJ represents the signal from the contact 62 converted into a logic level, and indicates that the rotating body has reached a predetermined speed or higher after a period of time since it started rotating. The fifth column represents the signal after receiving the signal PZ at the line receiver 21 and converting it to a logic level,
This shows how a pulse is output every time the rotating body rotates once after the rotating body starts rotating. Column (6) is Z
This is a signal input to the mutual switch 14, and the AND gate 1
7 represents a Z-phase pulse limited only to the period in which the rotating body reaches a predetermined speed or higher.

The (7)th column represents the output of the Z mutual switch 14. As shown in the figure, this Z mutual switch 14 becomes H level by the initial clear signal a after the power is turned on to the system.
Thereafter, the Z-phase pulse, which is output only when the rotating body reaches a predetermined speed or higher, is input and becomes L level.

Meanwhile, another signal PA from the position coder.

*PA, PB, and *PB are also input to the line receiver 21, where the level of *PA is subtracted from the level of PA to become the A phase signal, and the level of *PB is subtracted from the level of PB.
The level of is subtracted to obtain the B-phase signal. These A-phase and B-phase signals have a phase difference of 90° from each other, but when the rotating body is rotating in the forward direction, the A phase leads by 90°, and when the rotating body is rotating in the reverse direction, the B phase leads by 90°. Assume that 90@ is ahead. The waveform shaping circuit 22 is for converting the A-phase and B-phase signals into signals g and h synchronized with a basic clock (for example, 300 KHz).

FIG. 4 is for explaining the operation of the quadrupling circuit 23, but since this circuit is used in most general encoders and is well known, a detailed explanation will be omitted. To explain a part of it, if the B-phase signal (column (2)) is at the rising edge of the A-phase signal (column (IIJ)), a normal rotation pulse i (column (3)) is output, and even if it is H. In this case, a reversal pulse (column (4)) is output.The same process is performed in other cases.

FIG. 5 is a diagram for explaining the operation of the up/down counter 31. Since the output f of the Z-matching circuit 14 is connected to the enable input of this up-down counter, the output f of the Z-matching circuit 14 shown in column (1) is L.
Until the level is reached, the count value shown in column (4) remains O regardless of other inputs. Since the forward rotation pulse i shown in the (2) column is connected to the up input of the up/down counter 31, and the reverse rotation pulse j is connected to the down input, the Z phase clip circuit 14 catches the Z phase signal. When the output f becomes L level, the count value increases by 1 as the forward rotation pulse is input, and the count value decreases by IM as the reverse rotation pulse is input. This up/down counter has a 10-bit configuration, so all bits are 1, meaning the count value is 10.
23, the carry signal k shown in No. (5) 41jl
becomes H level. This signal is close to the desired corrected Z-phase signal, but in order to obtain more accurate timing, the following processing is performed.

FIG. 6 is a diagram for explaining the operation of the circuits surrounding the differentiating circuit 32 and the direction determining circuit 33, and explains the operation of the circuit for forming an accurate corrected Z-phase pulse from the carry signal k. This is a diagram for

When the forward rotation pulse i ((1st) jM) is inputted to the direction discrimination circuit 33, its output n ((3rd) column) becomes H level, and when the reverse rotation pulse j ((2)th l) is inputted, It becomes L level. Therefore, the output n outputs a signal level corresponding to the rotational direction of the rotating body.

The differentiating circuit 32 detects the rising and falling edges of the input signal k ((4th) column) and outputs pulses with the width of the basic clock as 1 ((5th)!Ijl) and m ((6th) Ijl), respectively.
). By the action of the inverting circuit 34 and the AND gates 35 and 36, a signal as shown in column (7) is outputted to the output p.

This signal is output at the falling edge of the carry signal during forward rotation and at the rising edge during reverse rotation, so these are output when the count value is 1023 to Ol and 0 to 10.
23 (column (8)), it is output with the width of the basic clock, and a corrected Z-phase signal is obtained.

〔Effect of the invention〕

As described above, according to the present invention, the output timing of the one-rotation signal output from the position coder is not affected by ambient temperature, fluctuations in power supply voltage, noise, etc.
A signal correction circuit is provided that corrects the signal so that it is always output at a constant rotational position.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the principle of the present invention, FIG. 2 is a circuit block diagram of an embodiment of the present invention, FIG. 3 is a diagram explaining the operation of the Z mutual switch circuit in the embodiment of FIG. Figure 4 is a diagram explaining the operation of the quadruple circuit in the embodiment of Figure 2, Figure 5 is a diagram explaining the operation of the amplifier down counter in the embodiment of Figure 2, and Figure 6 is the implementation of Figure 2. Figure 7 is a diagram illustrating the operation of the differential circuit, direction discrimination circuit, and peripheral circuits in the example; Figure 7 is a diagram illustrating a position coder using a magnetoresistive element; Figure 8 is a diagram illustrating a conventional Z-phase signal processing method. It is. In the figure, 20...position coder, AB...rotation position signal, Z...1 rotation signal.

Claims (1)

[Claims] 1. Rotational position signal (AB) corresponding to the rotational position of the rotating body
and a one-rotation signal (Z) corresponding to one rotation of the rotary body. , one-rotation signal latch means for capturing the output timing of the first one-rotation signal after the power is turned on to the device in which the correction circuit is incorporated, among the one-rotation signals while the rotational speed of the rotating body is equal to or higher than a predetermined speed; (10), counting is permitted at the output timing of the one rotation signal captured by the one rotation signal latch means (10), and each rotation position signal (AB) is counted a predetermined number of times. 1. A one-rotation signal correction circuit for a position coder, comprising counter means (30) for outputting a carry signal (Z') corresponding to a rotation signal.