JPH05223594A - Transfer information detector using encoder - Google Patents

Abstract

PURPOSE:To obtain the information detector which can exactly prevent misjudg ment due to chattering or bounds and detect the transfer direction and the transfer distance of a measurement object. CONSTITUTION:The following are provided: a means 3b for sampling encoder output; a wave-shaping means 4b for correcting sampling data during discontinuity of high level state by a predetermined sampling turn or more; and a pulse edge detecting means 5 for detecting a phase variation of a plurality of wave- shaped pulse signals different in phase. Further provided are a means for stopping count upon simultaneous variation of a plurality of pulse signals and a direction judging means for judging that the transfer direction of a measurement object is invariable upon simultaneous variation of a plurality of pulse signals and even variation of any pulse signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving information detecting device for detecting a moving distance and a moving direction of an object to be measured based on an encoder output signal.

[0002]

2. Description of the Related Art Conventionally, two pulse signals of A phase and B phase are generated from an encoder according to the movement of an object to be measured, and the moving direction is discriminated from the phase difference between the both pulse signals. There is a device that detects the amount of movement by counting the number of pulses.

The encoder includes mechanical type, optical type, magnetic type and the like. The optical type and magnetic type are large in size, large in power consumption and high in price as compared with the mechanical type. When electric power is required, a mechanical type is used.

By the way, since the mechanical encoder generates a pulse signal having a cycle corresponding to the speed by a mechanical switch mechanism, the output signal contains a lot of noise. Therefore, in the conventional encoder, as shown in FIG. 9, noise is removed from the pulse signal output from the encoder 1 through a low-pass filter including a resistor and a capacitor, and then the phase difference is detected and the number of pulses is counted. ..

FIG. 10 shows the principle of a mechanical encoder. As shown in the figure, the rectangular wave-shaped movable parts having different phases are provided with contacts for A-phase and B-phase, respectively. By moving the movable part in conjunction with the movement of the object to be measured, the contactor and the movable part are repeatedly turned on and off, and a pulse signal is output from each of the A-phase and B-phase contactors. Since the number of pulses of both pulse signals corresponds to one period of the rectangular wave in the movable part, the moving distance can be known by counting the number of pulses. Further, when the object to be measured is moving in the same direction, the phase relationship between the two pulse signals does not change, so it is possible to determine that the moving direction has been reversed at the time when the phase change occurs. As described above, since the mechanical encoder generates a pulse signal by the mechanical contact between the contact and the movable part, chattering may occur at the time of switching or the contact may be momentarily separated in the ON state. There is a high possibility that there will be bounces that will be turned off.

When the chattering or the bounce caused by the above-mentioned cause is much smaller than the frequency of the actual pulse signal, it can be removed by the low pass filter shown in FIG.

[0007]

On the other hand, when aiming at downsizing and cost reduction, the mechanical encoder has a simple structure. Therefore, when an encoder having such a simple structure is moved at high speed, etc. The frequency of the noise and the frequency of the pulse signal are close to each other. In order to remove such noise, the time constant of the low pass filter must be increased.

However, when a low-pass filter having a large time constant is used, the phase of both pulse signals is partially reversed as shown in FIG. 11 due to the difference between the rising and falling time constants due to the influence of the pull-up resistance. Or the pulse signal itself is buried as shown in FIG.
As a result, it becomes impossible to accurately detect the moving direction and the moving amount.

Also, the phenomenon of bounce is that when one of the contacts is in contact and sliding, it is momentarily separated, but as shown in FIG. 13, especially when the other contact is switched. There is a high possibility that it will be greatly separated from the vibration at the same time, and it will not be possible to determine the direction at that time, and the phase relationship will be reversed when returning from the bounce, so the direction opposite to the actual movement direction There is a problem of making an erroneous determination.

The present invention has been made in view of the above circumstances, and it is possible to reliably prevent erroneous determinations due to chattering and bounces, and to accurately detect the moving direction and moving distance of an object to be measured. An object is to provide a detection device.

[0011]

In order to achieve the above object, the present invention takes in a pulse signal output from an encoder according to the movement of an object to be measured and counts the number of pulses of the pulse signal to perform the measurement. In a movement information detection device for detecting a movement distance of a target object, means for sampling the pulse signal at a cycle shorter than the cycle, and sampling data obtained by the sampling by the sampling means have a high level for a predetermined number of times or more. When the state is not maintained, a waveform shaping means for correcting the sampling data to a low level is provided.

In order to achieve the above object, the present invention takes in a plurality of pulse signals having different phases output from the encoder according to the movement of the object to be measured, and calculates the pulse number and phase change of these pulse signals. In a movement information detection device for detecting the movement distance and movement direction of the measurement target object based on the pulse edge detection means for detecting a change in each of the pulse signals, and the pulse signal simultaneously changed by the pulse edge detection means When it is detected, a configuration including means for stopping the counting of the pulse signal,

Further, when the pulse edge detecting means detects that the plurality of pulse signals change at the same time, the moving direction of the object to be measured does not change even if any one of the pulse signals changes next time. It is configured to include a direction determining means for determining that there is.

[0014]

According to the present invention, the pulse signal output from the encoder is sampled by the sampling means at a cycle shorter than that cycle. When the sampling data does not remain in the high level state for a predetermined number of times or more, the waveform shaping means corrects the high level sampling data in the meantime to the low level. If the high level state is not maintained for a predetermined number of times or more, chattering is likely to occur. Therefore, by correcting the sampling data to low level, a pulse signal from which noise due to chattering is removed can be obtained.

Further, according to the present invention, the change of each pulse signal output from the encoder is detected by the pulse edge detecting means respectively, and as a result of this detection, when the pulse signals simultaneously change, the pulse signal count is counted. Is stopped. When the pulse signals change at the same time, the direction cannot be determined. Therefore, in such a case, counting is stopped to prevent counting in the wrong direction.

Further, according to the present invention, when a plurality of pulse signals change at the same time, it is determined that the moving direction of the object to be measured is unchanged even if any one of the pulse signals changes next time. Multiple pulse signals change at the same time or within a very short time when the other one bounces and changes due to the vibration when one is switched, so the next time the pulse signal changes is the time when the bounce returns. Becomes Therefore, it is possible to prevent the inconvenience that the signal is counted in the opposite direction due to the change of the signal at the time of returning from the bounce, and the uncounted portion is compensated.

[0017]

EXAMPLE An example of the present invention will be described below.
FIG. 1 shows a functional block diagram of a movement information detection device according to an embodiment.

This device is provided with A-phase and B-phase pulse signals a and b output from the encoder 1 and having different phases.
Are input to the corresponding low-pass filters 2a and 2b, respectively, and the outputs of the low-pass filters 2a and 2b are sampled by the sampling circuits 3a and 3b at a cycle sufficiently shorter than the pulse width of the pulse signals a and b.
The sampling signals obtained by sampling by the sampling circuits 3a and 3b are input to the corresponding waveform shaping circuits 4a and 4b, respectively.

The waveform shaping circuits 4a and 4b shape the input signal into a pulse signal from which noise such as chattering is removed by signal processing described later. This waveform shaping circuit 4
The output signals of a and 4b are input to the edge pulse output circuit 5, the direction determination circuit 6, and the simultaneous change detection circuit 7, respectively.

The edge pulse output circuit 5 detects the rising edge and the falling edge of the input signal, and outputs the detection result as a count pulse signal to the count circuit 9 via the pulse cutoff circuit 8. The direction determination circuit 6 determines the moving direction or rotation direction of the object to be measured from the phase information of both input signals, and outputs the direction determination signal to the counting circuit 9 via the determination inversion circuit 10.

The simultaneous change detection circuit 7 outputs a simultaneous change detection signal to the pulse interruption circuit 8 and the simultaneous change detection holding circuit 11 when both input signals change simultaneously or within an extremely short time. The pulse cutoff circuit 8 receives the simultaneous change detection signal from the simultaneous change detection circuit 7 and cuts off the input of the count pulse to the count circuit 9.

The decision inversion circuit 10 holds the simultaneous change detection signal from the simultaneous change detection circuit 7 by the simultaneous change detection and holding circuit 11 so that the direction decision signal from the direction decision circuit 6 is inverted at the next edge. Further, the inverted direction determination signal is output to the counting circuit.

The count circuit 9 counts the number of pulses of the count pulse signal input from the edge pulse output circuit 5 via the pulse cutoff circuit 8, and the direction determination signal input from the direction determination circuit 6 via the determination inversion circuit 10. The count value is output by increasing or decreasing the count value. Specific circuit configurations of this embodiment are shown in FIGS.

The low pass filter 2a includes resistors r1 and r
2 and a capacitor C1 and is set to a time constant that does not affect the phase relationship between the encoder output signals a and b.

The output of the low-pass filter 2a is input to the D terminal of the flip-flop 21 which serves as the sampling circuit 3a. The sampling circuit 3a operates with a clock CLK2 obtained by dividing the system clock CLK1 by 2 in the flip-flop 20. That is, the encoder output signal is sampled at a sampling clock half the system clock CLK1.

In the waveform shaping circuit 4a, the output of the sampling circuit 3a is input to the D terminal of the flip-flop 22 provided in its input stage. Q of this flip-flop 22
The outputs are input to the AND circuits 23 and 24, respectively. The output of the sampling circuit 3a is further input to the input terminal of one of the AND circuits 23. AND of these two
The outputs of the circuits 23 and 24 are input to both input terminals of the OR circuit 25, and the output of the OR circuit is input to the D terminal of the flip-flop 26 provided in the output stage. The Q output of the flip-flop 26 is input to the edge pulse output circuit 5 and the input terminal of the other AND circuit 24.
The flip-flops 22, 2 of the waveform shaping circuit 4a are
6 also operates on the same clock CLK2 as the sampling circuit 3a.

The low-pass filter 2b, the sampling circuit 3b, and the waveform shaping circuit 4b corresponding to the phase B side of the encoder 1 also have the same configuration as the above-described phase A side.

The edge pulse output circuit 5 includes flip-flops 27 and 28 and an exclusive OR circuit 29 for each phase.
30 are provided respectively. Flip flop 2
The outputs S1 and S2 of the waveform shaping circuits 4a and 4b are input to the 7 and 28 and the exclusive OR circuits 29 and 30, respectively. The Q outputs of the corresponding flip-flops 27 and 28 are input to the other input terminals of the exclusive OR circuits 29 and 30, respectively.

The direction determination circuit 6 is composed of six flip-flops 31 to 36, an OR circuit 37, and an inverter 38. The D terminals of the flip-flops 31 and 32 are
Flip-flops 27, 28 of the edge pulse output circuit 5
The respective Q outputs S5 and S6 are input. Flip flop 3
Reference numerals 3 to 36 are used for the direction determination, and the Q output (non-inverted) and the inverted output of the flip-flops 31 and 32 are combined and input to the D terminal and the clock terminal thereof as shown in the figure.

On the other hand, the OR circuit 37 has outputs S3 of the exclusive OR circuits 29 and 30 of the edge pulse output circuit 5, respectively.
S4 is input. The output S7 of the OR circuit 37 is input to each clear terminal of the flip-flops 33 to 36 via the inverter 38. These flip-flops 3
The Q outputs of 3-36 are input to the OR circuit 39, and
The R circuit output S9 is output to the decision inversion circuit 10.

The simultaneous change detection circuit 7 outputs the OR circuit 37 shared with the direction inversion circuit 6, the exclusive OR circuit 41 shared with the pulse interruption circuit 8, and the outputs of the OR circuit 37 and the exclusive OR circuit 41. Exclusive OR circuit 42 to be input
And a flip-flop 43 to which the output of the exclusive OR circuit 42 is input. The exclusive OR circuit 41, like the OR circuit 37, outputs the signals S3 and S.
4 is input.

In the pulse cutoff circuit 8, the exclusive OR circuit 41 to which the signals S3 and S4 from the edge pulse output circuit 5 are input, and the output S10 of this exclusive OR circuit 41 is input to the D terminal and the inverted output is obtained. Of the flip-flop 44 for outputting as a count pulse S13. The inverted output S13 of the flip-flop 44 is output to the count circuit 9 as a count pulse.

The simultaneous change detection / holding circuit 11 comprises a flip-flop 45. This flip-flop 45 is D
A constant voltage is applied to the terminal, the inverted output S13 of the flip-flop 44 of the pulse cutoff circuit 8 is input to the clock terminal, and the inverted output S12 of the flip-flop 43 is input to the clear terminal.

The decision inverting circuit 10 includes an exclusive OR circuit 4
6 and uses the inverted output S14 of the flip-flop 45 and the output S9 of the OR circuit 39 of the direction determination circuit 6 as input signals. The output S15 of the exclusive OR circuit 46 is output to the counting circuit 9 as a direction determination signal. The present embodiment configured as described above exhibits the following operation.

First, a noise removing operation such as chattering in the waveform shaping circuits 4a and 4b will be described with reference to FIG. Since the noise removal operation in each of the waveform shaping circuits 4a and 4b is the same operation, the waveform shaping circuit 4a on the A phase side will be described here.

The data C output from the encoder 1 and sampled by the sampling circuit 3a at a sampling clock half the system clock CLK1 is held for two clocks by the flip-flops 22 and 26, and the sampling data c and the sampling data c are stored. The sampling data d one clock before is compared by one AND circuit 23, and the sampling data d and the sampling data e one clock before that are compared by the other AND circuit 24. When the sampling data d is at the high level and the data c and e before and after it are at the low level, the AND circuits 23 and 24 are both not established and the flip-flop 2
Data obtained by modifying the sampling data d to a low level is input to 6, and the modified data S1 is output to the edge pulse output circuit 5 at the next clock.

Therefore, in the waveform shaping circuit 4a, when the high level state does not continue for 2 samples or more, it is regarded as chattering, and the output signal e related to the data is corrected to the low level. Chattering noise is removed by such processing. The operation subsequent to the waveform shaping circuit 4 will be described with reference to the time charts shown in FIGS. 6 and 7.

In the pulse edge output circuit 5, the waveform-shaped data S1 and S2 are flip-flops 27 and 28.
Are input to the flip-flops 27 and 28, respectively.
Operates at the falling edge of the system clock CLK1 and outputs signals S5 and S6 delayed by half a clock, respectively.

On the other hand, in the exclusive OR circuits 29 and 30,
The waveform-shaped signals S1 and S2 and the signals S5 and S6 delayed by half a clock from them are input, respectively. Then, when the signals S1 and S2 change, pulse signals S3 and S4 for half a clock are output. In this way, pulse signals S3 and S4 for half a clock are output when the waveform-shaped signals S1 and S2 change.

In the direction determining circuit 6, first, the OR circuit 37 synthesizes the pulse signals S3 and S4, and the synthesized signal S7 synthesizes the direction determining flip-flops 33 to 36.
Is reset. After that, flip-flops 31, 3
The pulse signals S3 and S4 indicating the edge portions of the A phase and B phase delayed by 2 are input to the flip-flops 33 to 36, and the direction determination result is output as the direction determination signal S9.

On the other hand, the pulse signals S3 and S4 indicating the edge portions of the A-phase and B-phase signals S1 and S2 are input to the exclusive OR circuit 41 of the pulse cutoff circuit 8. In the exclusive OR circuit 41, the output S10 becomes low level when the pulse signals S3 and S4 change at the same time. Then, both output signals S10 and S7 of the exclusive OR circuit 41 and the OR circuit 37 are inputted to the exclusive OR circuit 42, the pulse S7 is outputted from the OR circuit 37, and the pulse S10 is outputted from the exclusive OR circuit 41. Is not output, that is, the simultaneous change detection signal S11 is output only when the A-phase and B-phase signals S1 and S2 simultaneously change.

The flip-flop 43 is inserted to remove the glitch noise from the exclusive OR circuit 42, and outputs the negative simultaneous change detection signal S12.

The simultaneous change detection signal S12 is input to the clear terminal of the flip-flop 45 of the simultaneous change detection holding circuit 11, and the pulse signal S10 of the pulse cutoff circuit 8 is counted through the flip-flop 44 and its inverted output S13 is counted. It is held until output to the circuit 9. Then, while the simultaneous change detection holding circuit 11 holds the simultaneous change detection pulse S12, the inverted output S of the flip-flop 45 is obtained.
Since 14 is at a high level, the decision inversion circuit 10
By the exclusive OR circuit 46, the decision output S9 of the direction decision circuit 6 is inverted and the signal S15 is input to the count circuit 9.

In the count circuit 9 to which the count pulse S13 and the direction determination signal S15 are input, as shown in FIG. 8, when the encoder signals change at the same time, the input of the count pulse S13 is cut off. No counting is performed, and when the bounce is restored, counting is started in the same direction.

As described above, according to the present embodiment, when the waveform shaping circuits 4a and 4b do not maintain the high level state for a certain number of times or more, it is determined that the sampling data is chattering noise. Since the data is corrected to low level, chattering can be digitally removed without using a low-pass filter with a large time constant, the phase is reversed and the judgment result of the moving direction is incorrect,
It is possible to reliably prevent the inconvenience that the signal is buried and the moving distance and the moving direction cannot be detected.

Further, encoder signals a and b for A phase and B phase
, The output of the count pulse S13 is stopped by the pulse interruption circuit 8 and the moving direction is reversed by the pulse change in the first pulse change after the encoder signals a and b have changed simultaneously. I decided to reverse the direction judgment result so that it would not be judged,
It is possible to prevent counting in the wrong direction when the direction cannot be determined.
It is possible to prevent counting in the wrong direction when returning from the bounce, and it is possible to compensate for the amount that could not be counted because the direction cannot be determined.

[0047]

As described above in detail, according to the present invention, it is possible to reliably prevent erroneous determinations due to chattering and bounces.
It is possible to provide a movement information detection device that can accurately detect the movement direction and movement distance of a measurement target object.

[Brief description of drawings]

FIG. 1 is a functional block diagram of a movement information detection device according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram of a front stage of the movement information detection device according to the embodiment.

FIG. 3 is a circuit configuration diagram of the middle stage of the movement information detection device according to the embodiment.

FIG. 4 is a circuit configuration diagram of a rear stage of the movement information detection device according to the embodiment.

FIG. 5 is a diagram showing a time chart of a waveform shaping circuit part showing a chattering noise removal operation.

FIG. 6 is a diagram showing a part of a time chart of a portion related to a direction reversal process of the movement information detection device according to the embodiment.

FIG. 7 is a diagram showing a time chart relating to direction reversal processing at the final stage of the movement information detection apparatus according to the embodiment.

FIG. 8 is a diagram for explaining a counting result associated with the direction reversal processing of the movement information detection device according to the embodiment.

FIG. 9 is a diagram showing a conventional mechanical encoder and its signal processing circuit.

FIG. 10 is a diagram for explaining the operation principle of a mechanical encoder.

FIG. 11 is a waveform diagram affected by chattering noise using a low-pass filter having a low time constant.

FIG. 12 is a waveform diagram of an output signal of an encoder when a low pass filter having a high time constant is used.

FIG. 13 is a diagram showing a phase change due to bounces at the time of switching.

[Explanation of symbols]

1 ... Encoder, 2 ... Low-pass filter, 3 ... Sampling circuit, 4 ... Waveform shaping circuit, 5 ... Edge pulse output circuit, 6 ... Direction determination circuit, 7 ... Simultaneous change detection circuit, 8 ... Pulse interruption circuit, 9 ... Count circuit 10 ... Judgment inversion circuit, 11 ... Simultaneous change detection holding circuit.

Claims (3)

[Claims] 1. A movement information detection device for taking in a pulse signal output from an encoder according to the movement of an object to be measured, counting the number of pulses of the pulse signal, and detecting a moving distance of the object to be measured, When the pulse data is sampled at a cycle shorter than the cycle, and the sampling data obtained by the sampling by the sampling means does not maintain a high level state for a predetermined number of times or more, the sampling data is set to a low level. A movement information detection device, comprising: a waveform shaping unit that corrects the level. 2. A plurality of pulse signals output from an encoder and having different phases according to the movement of the measurement target object are taken in, and the movement distance and movement of the measurement target object are based on the number of pulses and phase change of these pulse signals. In a movement information detection device for detecting a direction, a pulse edge detection unit that detects a change in each of the pulse signals, and the pulse signal when the pulse edge detection unit detects that each pulse signal changes at the same time A movement information detecting device comprising: means for stopping counting. 3. When the pulse edge detection means detects that the plurality of pulse signals have changed at the same time, the moving direction of the object to be measured is unchanged even if any of the pulse signals changes next time. 3. The movement information detecting device according to claim 2, further comprising direction determining means for determining that