JP2903736B2 - Disconnection detection circuit of pulse generator - Google Patents

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 disconnection of a pulse generator which is coupled to a rotating body and outputs two sets of pulse signals for detecting the rotating speed and the rotating direction of the rotating body.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a conventional example in which a rotation speed and a rotation direction of a rotating body are detected by a pulse generator coupled to the rotating body. As a rotating body, for example, a pulse generator is coupled to detect the rotation speed and rotation direction of the electric motor. The pulse generator has a predetermined number of A pulses per rotation and a predetermined phase difference ( And a B pulse having a phase difference of 90 degrees is generally output. The conventional circuit shown in FIG. 6 includes a counter 3 and a D flip-flop 7. The counter 3 counts the number of A-pulses input from the A-pulse input terminal 2 to detect the rotation speed of the electric motor. From the speed signal output terminal 4. The A pulse from the A pulse input terminal 2 is applied to the D terminal of the D flip-flop 7 and
When the B pulse from the pulse input terminal 6 is input to the C terminal of the D flip-flop 7 as a clock signal, the rotation direction signal output terminal 8
, The rotation direction signal of the motor can be extracted.

FIG. 7 is a time chart showing an operation of detecting that the motor is running forward in the conventional circuit shown in FIG. 6, where A is a pulse, B is a pulse, and Q is a Q of the D flip-flop 7. Each output signal from the terminal is represented. When the clock signal, that is, the B pulse, falls, the D flip-flop 7 outputs the logical L signal of the A pulse input to the D terminal as it is from the Q terminal. The output from the Q terminal is always a logical L signal.

FIG. 8 is a time chart showing an operation of detecting that the motor is in reverse rotation in the conventional circuit shown in FIG. 6, where A is a pulse, B is a pulse, and Q is a Q terminal of a D flip-flop 7. Are the same as in the case of FIG. 7 described above. In the above-described forward rotation operation of the motor, the B pulse is shifted from the A pulse by 90
Although the phase is delayed by a degree (see FIG. 7), the phase of the B pulse is ahead of the phase of the A pulse by 90 degrees during the reverse rotation operation. Therefore B
Since the A pulse is a logic H signal at the time of the falling edge of the pulse, the logic H signal is always output from the Q terminal of the D flip-flop 7.

[0005]

As described above, when the A pulse and the B pulse output from the pulse generator are given to the D flip-flop 7, the logical signal output from the D flip-flop 7 indicates the rotation direction of the motor. Can be determined. Here, if the A-pulse circuit of the pulse generator is disconnected, the value of the rotation speed signal output from the counter 3 changes abruptly. If it is detected that the degree of this speed change is abnormally large, It is easy to detect a disconnection. However, if the B-pulse circuit is disconnected, the control will be confused if only the logical signal for determining the rotation direction changes despite the fact that the motor rotation direction remains unchanged. If the logic signal for the direction determination does not change, this disconnection cannot be detected, and there is a disadvantage that an abnormality occurs when the rotation direction of the motor is switched.

Accordingly, an object of the present invention is to quickly and surely detect a disconnection of an output circuit of a pulse generator connected to a rotating body for detecting a rotation speed and a rotation direction. An object of the present invention is to prevent the occurrence of an abnormality due to the above.

[0007]

In order to achieve the above object, a disconnection detecting circuit according to the present invention comprises 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 the rotating body, and the pulse generator detects the rotation speed and the rotating direction of the rotating body. A signal output from the A / D converter is input to an up-counter of an up-down counter, a B-pulse is input to a down-count terminal, and an output terminal of the most significant digit signal of the up-down counter inverts the output signal. And an output signal of the remaining digits excluding the most significant digit of the up / down counter and an output signal of the signal inversion element are input to a logical product element, and the logical signal output from the logical product element is obtained by inverting the logical signal. A flip-flop for detecting disconnection of the pulse generator or inputting an output signal of the AND element; From the inverted logic signal of flip-flop, and outputs the detected disconnection of the pulse generator shall raise an alarm.

[0008]

According to the present invention, A
By inputting a pulse to the up-count terminal of the up-down counter and a B pulse to the down-count terminal of the up-down counter, the up-down counter always counts zero if both pulse circuits are normal. , B pulse circuit counts up when the A pulse circuit is disconnected, and conversely, when the A pulse circuit is disconnected, the B pulse is counted down. A signal inverting element for inverting the most significant digit output signal of the up / down counter and a logic for inputting the output signal of the signal inverting element and the output signal of the remaining digits of the up / down counter to the next stage of the up / down counter By providing a product element, a disconnection alarm is output when the number of A pulses counted up or the number of B pulses counted down reaches a predetermined number.

[0009]

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the circuit of the first embodiment, an A pulse input terminal 2, a counter 3, a speed signal output terminal 4, and a B pulse input terminal shown in FIG. The names, applications, and functions of the terminal 6, the D flip-flop 7, and the rotation direction signal output terminal 8 are the same as those used in the conventional circuit described above with reference to FIG.

In the circuit of the first embodiment, an A-pulse is input to the up-count terminal of the up-down counter 11 which outputs a 4-digit signal, and a B-pulse is input to the down-count terminal. the Q _D terminal for outputting the digit signal, connecting the signal inversion device 12 for inverting the logic of this signal. Further residual signal output terminal Q _C of the up-down counter 11, Q _B, Q _A and the signal from the (terminal Q _A outputs the least significant digit signal), the output signal and a logical product of the signal inverting element 12 Input to the element 13. With such a circuit configuration, when either the A pulse circuit or the B pulse circuit is disconnected, the up / down counter 11 sets the AND element 13 when the count value of the pulse number reaches a predetermined value by down counting or up counting. Is inverted, the inverted signal is taken out via the alarm signal output terminal 14, and a disconnection alarm is issued. The counter clear signal input terminal 15 is a terminal for inputting a signal when the up / down counter 11 is cleared.

FIG. 2 is a time chart showing the operation of the circuit of the first embodiment shown in FIG. 1 when the pulse generator is not disconnected. _A terminal (lowest digit terminal)
The output of the output of the Q _B terminal, the output of Q _C terminal,
Each represents the output of Q _D terminal (the most significant digit terminal). As is apparent from FIG. 2, since the down-counting is performed by the B-pulse immediately after the up-counting by the A-pulse, the pulse count value of the up-down counter 11 does not increase, and therefore, the disconnection alarm is not output naturally.

[0012] Figure 3 is Q _A terminal of the first embodiment a time chart showing the operation of the circuit, the A-pulse, the B pulse, the up-down counter 11 shown in FIG. 1 when the B pulse circuit is broken the output of the (least significant digit terminal), the output of the Q _B terminal, the output of Q _C terminal, the output of the Q _D terminal (most significant digit terminal), is represents the outputs of the aND gate 13 is. If the B pulse circuit is disconnected, the up / down counter 11 continues to count up by the A pulse, and all the input signals of the AND element 13 become logic H signals at the time T _1.
Is switched from the logical L signal to the logical H signal, and the disconnection of the pulse generator is detected. Note the output signal of the AND gate 13 returns to a logic L signal T ₂ time.

[0013] Figure 4 is a time chart showing the operation of the first embodiment circuit shown in Figure 1 when A pulse circuit is broken, the A-pulse, the Q _A terminal of the up-down counter 11 B pulses, are the output of the (least significant digit terminal), the output of the Q _B terminal, the output of Q _C terminal, the output of the Q _D terminal (most significant digit terminal), is represents the outputs of the aND gate 13 is. When A pulse circuit is disconnected, the up-down counter 11 by B pulses continues counting down, since the input signal of the AND gate 13 at T ₃ time all become logic H signal, the AND gate 13
Is switched from the logical L signal to the logical H signal, and the disconnection of the pulse generator is detected. Note the output signal of the AND gate 13 returns to a logic L signal T ₄ time.

FIG. 5 is a block diagram showing a second embodiment of the present invention. In the circuit of the second embodiment, an A pulse input terminal 2, a counter 3, a speed signal output terminal 4, and a B pulse input terminal are shown. 6, the names, applications and functions of the D flip-flop 7 and the rotation direction signal output terminal 8 are the same as those used in the conventional circuit described above with reference to FIG.
1. Names of signal inverting element 12, AND element 13, alarm signal output terminal 14, and counter clear signal input terminal 15
The applications and functions are the same as those used in the circuit of the first embodiment described above with reference to FIG.

The circuit of the second embodiment is the same as that of the first embodiment shown in FIG.
The output signal of the AND element 13 in the circuit of the embodiment is
The circuit is configured to take out via the flip-flop 21. In the circuit of the first embodiment, the AND element 1
Output period of disconnection alarm 3 outputs are very short period from T ₁ time to T ₂ time (see FIG. 3), or from T ₃ time point T ₄ time points (see Figure 4). Therefore, in the circuit of the second embodiment, the disconnection alarm output from the AND element 13 is held by the next-stage SR flip-flop 21 to make the disconnection alarm more reliable. Here, the reset signal input terminal 22 is a terminal for inputting a signal for resetting the SR flip-flop 21.

[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, respectively. Since the circuit is configured to output a disconnection alarm when a predetermined number of pulses are counted by the up / down counter, disconnection of the pulse generator output circuit can be detected quickly and reliably. It is possible to prevent a danger that the operation of a rotating body such as an electric motor that controls the speed and the rotation direction in combination is hindered. Further, by converting the pulse-shaped disconnection alarm signal into a continuous signal using a flip-flop, an effect that the disconnection detection can be more reliably obtained is obtained.

[Brief description of the drawings]

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

FIG. 2 when the pulse generator is not disconnected
Showing the operation of the circuit of the first embodiment shown in FIG.

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;

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;

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

FIG. 6 shows a pulse generator coupled to a rotating body,
Block diagram showing a conventional example of detecting the rotation speed and rotation direction of this rotating body

FIG. 7 is a time chart showing an operation of detecting that the electric motor is in normal rotation operation in the conventional circuit shown in FIG. 6;

FIG. 8 is a time chart showing an operation of detecting that the motor is in reverse rotation in the conventional 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)

(57) [Claims] A pulse generator for outputting a predetermined number of A pulses for each rotation and a B pulse having a predetermined phase difference from the A pulse is coupled to a rotating body, and the rotation speed of the rotating body is determined. In the pulse generator that detects the rotation direction, the A pulse output from the pulse generator is input to an up-count terminal of an up-down counter, and the B pulse is input to a down-count terminal. A signal inverting element for inverting the logic of this output signal is connected to the output terminal, and the output signal of the remaining digits excluding the most significant digit of the up / down counter and the output signal of the signal inverting element are input to an AND element. Detecting a disconnection of the pulse generator based on an output of the AND element. Road. 2. The pulse generator according to claim 1, further comprising a flip-flop for inputting an output signal of said AND element, and detecting a disconnection of said pulse generator based on an output of said flip-flop. Detection circuit.