JPH04278470A - Disconnection detection circuit of pulse generator - Google Patents

Abstract

PURPOSE:To prevent the control of a rotary body from becoming impossible by rapidly and certainly detecting the disconnection of the output circuit of the pulse generator connected to the rotary body in order to detect the rotational speed and rotary direction of the rotary body. CONSTITUTION:The A-pulse and B-pulse from a pulse generator are respectively inputted to the incremental and decremental terminals of an incremental and decremental counter 11 and, at the time of the disconnection of a B-pulse circuit, the A-pulse is incrementally counted and, at the time of the disconnection of an A-pulse circuit, the B-pulse is decrementally counted. A signal reversal element 12 reversing the logic of the uppermost figure output signal of the incremental and decremental counter and an AND element 13 receiving the output of the signal reversal element and the output of the residual figure of the incremental and decremental counter are provided to the next stage of the incremental and decremental counter and, when the counted number of pulses of the incremental and decremental counter reaches a predetermined value, a disconnection alarm is outputted.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit for detecting a disconnection in a pulse generator connected to a rotating body and outputting two sets of pulse signals for detecting the rotational speed and direction of the rotating body.

0002

2. Description of the Related Art FIG. 6 is a block diagram showing a conventional example in which the rotational speed and direction of a rotating body are detected by a pulse generator coupled to the rotating body. For example, a pulse generator is coupled to detect the rotation speed and rotation direction of an electric motor as a rotating body, and this pulse generator generates a predetermined number of A pulses for each rotation, and a predetermined phase difference ( It outputs two sets of pulse signals consisting of a B pulse and a B pulse having a phase difference of 90 degrees (generally). The conventional example circuit shown in FIG. 6 includes a counter 3 and a D flip-flop 7, and detects the rotational speed of the motor by counting the A pulse input from the A pulse input terminal 2 with the counter 3, and detects the rotation speed of the motor. is taken out from the speed signal output terminal 4. In addition, the A pulse from the A pulse input terminal 2 is input to the D terminal of the D flip-flop 7, and
When the B pulse from the pulse input terminal 6 is input as a clock signal to the C terminal of the D flip-flop 7, the rotation direction signal output terminal 8 is output from the Q terminal of the D flip-flop 7.
The rotational direction signal of the electric motor can be extracted through the .

FIG. 7 is a time chart showing the operation of detecting that the motor is operating in the normal rotation in the conventional circuit shown in FIG. 6, in which ■ indicates the A pulse, ■ indicates the B pulse, and ■ indicates the D flip-flop. Each represents the output signal from the Q terminal of No.7. Since the D flip-flop 7 outputs the logic L signal of the A pulse input to the D terminal as it is from the Q terminal at the time when the clock signal, that is, the B pulse falls, it is in normal rotation as shown in FIG. The output from the Q terminal is always a logic L signal.

FIG. 8 is a time chart showing the operation of detecting that the motor is running in reverse in the conventional circuit shown in FIG. Each represents the output signal from the Q terminal of , as in the case of FIG. 7 described above. When the motor is running in the forward direction as described above, the B pulse is 90° from the A pulse.
However, during reverse operation, the B pulse is 90 degrees ahead of the A pulse in phase (see FIG. 7). Therefore B
Since the A pulse is a logic H signal at the falling edge of the pulse, the Q terminal of the D flip-flop 7 always outputs a logic H signal.

[0005]

[Problems to be Solved by the Invention] As mentioned above, when the A pulse and B pulse output from the pulse generator are applied to the D flip-flop 7, the logical signal output from the D flip-flop 7 determines the direction of rotation of the motor. can be determined. If the A-pulse circuit of the pulse generator is disconnected, the value of the rotational speed signal output from the counter 3 will suddenly change, so if it is detected that the degree of this speed change is abnormally large, the A-pulse circuit Detecting a wire break is easy. However, if the B pulse circuit is disconnected, the control will be confused if only the logic signal for determining the rotation direction changes even though the motor rotation direction remains unchanged, and even if the B pulse circuit is disconnected, the motor will not rotate. This disconnection cannot be detected unless the logic signal for determining the direction changes, which causes an inconvenience that an abnormality occurs when the rotational direction of the motor is switched.

Therefore, an object of the present invention is to quickly and reliably detect the disconnection when the output circuit of the pulse generator connected to the rotating body for detecting the rotational speed and direction is disconnected. The aim is to prevent abnormalities from occurring due to

[0007]

[Means for Solving the Problems] In order to achieve the above object, the disconnection detection circuit of the present invention is configured to detect a predetermined number of A per rotation.
A pulse generator that outputs a pulse and a B pulse having a predetermined phase difference from the A pulse is coupled to a rotating body to detect the rotational speed and direction of the rotating body, wherein the pulse generator A signal inversion element that inputs the A pulse outputted by the up-down counter to the up-count terminal, inputs the B pulse to the down-count terminal, and inverts this output signal to the output terminal of the most significant digit of the up-down counter. and input the output signals of the remaining digits of the up-down counter except for the most significant digit and the output signal of the signal inverting element to an AND element, and from the inversion of the logic signal output by this AND element, the A flip-flop is provided that detects a break in the pulse generator or inputs the output signal of the AND element, and detects a break in the pulse generator from the inversion of the logic signal output by the flip-flop and issues an alarm. .

[0008]

[Operation] This invention provides the A
By inputting the pulse to the up-count terminal of the up-down counter and the B pulse to the down-count terminal of this up-down counter, if both pulse circuits are normal, this up-down counter will always count zero. , when the B pulse circuit is disconnected, the A pulse is counted up, and conversely, when the A pulse circuit is disconnected, the B pulse is counted down. At the next stage of this up-down counter, there is a signal inverting element that inverts the most significant digit output signal of the up-down counter, and logic that inputs the output signal of this signal inverting element and the output signal of the remaining digits of the up-down counter. By providing a product element, a disconnection alarm is output when the number of up-counted A pulses or the number of down-counted B pulses reaches a predetermined number.

[0009]

[Embodiment] FIG. 1 is a block diagram showing a first embodiment of the present invention. The circuit of this first embodiment includes an A pulse input terminal 2, a counter 3, a speed signal output terminal 4, and a B pulse input terminal. The names, uses, and functions of the terminal 6, the D flip-flop 7, and the rotational direction signal output terminal 8 are the same as those used in the conventional circuit described in FIG. 6, so a description thereof will be omitted.

In this first embodiment circuit, an A pulse is input to the up count terminal of an up/down counter 11 which outputs a 4-digit signal, and a B pulse is input to the down count terminal. A signal inversion element 12 for inverting the logic of this signal is connected to the QD terminal that outputs the digit signal. Furthermore, the remaining signal output terminals QC, QB, QA (
The signal from the terminal from which QA outputs the least significant digit signal,
The output signal of the signal inverting element 12 is input to the AND element 13. By having such a circuit configuration, A
When either the pulse circuit or the B-pulse circuit is disconnected, the up/down counter 11 counts down or counts up, and when the pulse count reaches a predetermined value, the logical signal output from the AND element 13 is inverted. The signal reversal is taken out via the alarm signal output terminal 14 and a disconnection alarm is issued. In addition, the counter clear signal input terminal 15
is a terminal for inputting a signal for clearing the up/down counter 11.

FIG. 2 is a time chart showing the operation of the first embodiment circuit shown in FIG. 1 when the pulse generator is not disconnected, where ■ indicates the A pulse, ■ indicates the B pulse, and ■ indicates the up/down counter. 11, the output from the QA terminal (the least significant digit terminal), ■ the output from the QB terminal, ■ the output from the QC terminal, and ■ the output from the QD terminal (the most significant digit terminal), respectively. As is clear from FIG. 2, since the B pulse counts down immediately after the A pulse counts up, the pulse count value of the up/down counter 11 does not increase, and therefore, naturally, a disconnection alarm is not output.

FIG. 3 is a time chart showing the operation of the first embodiment circuit shown in FIG. 1 when the B pulse circuit is disconnected, where ■ indicates the A pulse, ■ indicates the B pulse, and ■ indicates the up/down counter 11. Output of QA terminal (least significant digit terminal), ■
is the output of the QB terminal, ■ is the output of the QC terminal, ■ is the QD
The output of the terminal (the most significant digit terminal) and ■ represent the output of the AND element 13, respectively. If the B pulse circuit is disconnected, the A pulse will cause the up/down counter 11 to
continues to count up, and at time T1, AND element 13
Since all of the input signals become logic H signals, the output signal of this AND element 13 switches from a logic L signal to a logic H signal, and it is detected that the pulse generator is disconnected. Note that the output signal of the AND element 13 returns to the logic L signal again at time T2.

FIG. 4 is a time chart showing the operation of the first embodiment circuit shown in FIG. 1 when the A pulse circuit is disconnected, where ■ indicates the A pulse, ■ indicates the B pulse, and ■ indicates the operation of the up/down counter 11. Output of QA terminal (least significant digit terminal),■
is the output of the QB terminal, ■ is the output of the QC terminal, ■ is the QD
The output of the terminal (the most significant digit terminal) and ■ represent the output of the AND element 13, respectively. If the A pulse circuit is disconnected, the up/down counter 11 is activated by the B pulse.
continues to count down, and at the time of T3, AND element 13
Since all of the input signals become logic H signals, the output signal of this AND element 13 switches from a logic L signal to a logic H signal, and it is detected that the pulse generator is disconnected. Note that the output signal of the AND element 13 returns to the logic L signal again at time T4.

FIG. 5 is a block diagram showing a second embodiment of the present invention, and the circuit of this second embodiment has an A pulse input terminal 2, a counter 3, a speed signal output terminal 4, and a B pulse input terminal. 6. The names, uses, and functions of the D flip-flop 7 and the rotational direction signal output terminal 8 are the same as those used in the conventional example circuit already described in FIG.
1. Names of signal inversion element 12, AND element 13, alarm signal output terminal 14, and counter clear signal input terminal 15.
Since the purpose and function are the same as those used in the first embodiment circuit already described in FIG. 1, a description thereof will be omitted.

This second embodiment circuit is similar to the first embodiment already described in FIG.
The output signal of the AND element 13 in the embodiment circuit is
The circuit is configured to take out the data through a flip-flop 21. In the circuit of the first embodiment described above, the AND element 1
The output period of the disconnection alarm output by 3 is from T1 to T2
(see Figure 3), or from T3 to T4
This is a very short period of time (see Figure 4). Therefore, in this second embodiment circuit, the disconnection alarm outputted from the AND element 13 is held by the SR flip-flop 21 at the next stage, thereby making the disconnection alarm more reliable. Here, the reset signal input terminal 22 is a terminal into which a signal for resetting the SR flip-flop 21 is input.

[0016]

According to the present invention, the A pulse output from the pulse generator is input to the up-count terminal of the up-down counter, and the B pulse is input to the down-count terminal of the up-down counter. The circuit is configured to output a disconnection alarm when the up-down counter counts a predetermined number of pulses, so disconnection in the pulse generator output circuit can be quickly and reliably detected. It is possible to prevent the possibility of hindrance to the operation of a rotating body such as an electric motor which is coupled to control the speed and direction of rotation. Further, by converting the pulsed wire breakage alarm signal into a continuous signal using a flip-flop, it is possible to achieve the effect of making wire breakage detection more reliable.

[Brief explanation of the drawing]

[Fig. 1] Block diagram showing a first embodiment of the present invention

[Figure 2
]A time chart showing the operation of the first embodiment circuit shown in FIG. 1 when the pulse generator is not disconnected.

[Figure 3]
A time chart showing the operation of the first embodiment circuit shown in FIG. 1 when the B pulse circuit is disconnected.

[Fig. 4] A time chart showing the operation of the first embodiment circuit shown in Fig. 1 when the A pulse circuit is disconnected.

FIG. 5 is a block diagram showing a second embodiment of the present invention.

[Fig. 6] Block diagram showing a conventional example of detecting the rotational speed and direction of a rotating body using a pulse generator coupled to the rotating body.

[Fig. 7] A time chart showing the detection operation of the motor in normal rotation operation in the conventional example circuit shown in Fig. 6.

[Fig. 8] A time chart showing the detection operation of the motor being in reverse operation in the conventional example circuit shown in Fig. 6.

[Explanation of symbols]

2 A pulse input terminal 3 Counter 4 Speed signal output terminal 6 B pulse input terminal 7 D flip-flop 8 Rotation direction signal output terminal 11 Up/down counter 12 Signal inversion element 13 Logical product element 14 Alarm signal output terminal 21 SR flip-flop

Claims (2)

[Claims] Claim 1: A pulse generator that outputs a predetermined number of A pulses and a B pulse having a predetermined phase difference from the A pulses per rotation is coupled to a rotating body, and the rotational speed of the rotating body is In a pulse generator that detects the direction of rotation, the A pulse outputted by the pulse generator is input to the up count terminal of an up/down counter, and the B pulse is input to the down count terminal, and the most significant digit signal of this up/down counter is input. A signal inversion element that inverts the logic of this output signal is connected to the output terminal, and the output signals of the remaining digits excluding the most significant digit of the up/down counter and the output signal of the signal inversion element are input to the AND element. A disconnection detection circuit for a pulse generator, characterized in that a disconnection of the pulse generator is detected based on the output of the AND element. 2. A disconnection of the pulse generator according to claim 1, further comprising a flip-flop inputting the output signal of the AND element, and detecting a disconnection of the pulse generator based on the output of the flip-flop. detection circuit.