JPS6091268A - Rotary speed and direction detecting apparatus - Google Patents

Abstract

PURPOSE:To eliminate erroneous speed detection when a rotary direction is changed over, by detecting the change in a rotary direction and removing the speed detection signal at this detection time as an error from a speed detection signal line. CONSTITUTION:A rotary speed detector 2 resets counting every when a signal RST is imparted and performs counting on the basis of the signals fA, fB from a two-phase pulse pick-up 1 or a combination thereof to output a counted value directly before the signal RST as a speed detection signal N. When there is change in a rotary direction during counting operation, a FF circuit 8 is set by the outputs of direction detectors 3, 4 and the error of the speed detection signal is transmitted to the side of a control apparatus main body by the output of said circuit 8 while the control apparatus main body neglects the speed detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotational speed/direction detection device using a two-phase pulse pickup.

In order to control the speed and nine rotational directions of a rotating body such as an electric motor, a detection device that can detect the speed and nine rotational directions of the rotary body is often required. A conventional device for this purpose includes a two-phase pulse pickup having a phase difference of 90 degrees and a logic element. This will be explained with reference to FIG. 1 and @2.

In FIG. 1, a two-phase pulse pickup 1 generates pulses fh and fB at a frequency corresponding to the rotational speed of the rotary body and whose phase is advanced or delayed by 90 degrees in accordance with the direction of rotation. The pulses f and fB are as shown in FIG.

The rotational speed detector 2 detects the rotational speed by counting the pulse f/tfB within a certain period of time, by counting the tarokk within a -period, or by a combination of these counts. Rotation direction detector 3
takes the pulse f as the input to the clock terminal C, and the pulse fB
By using a D-type flip-flop with data terminal input as
= Therefore, set and reset are detected in association with the rotation direction. In this case, the output from the Q output terminal is used as the rotational direction detection signal.

In this conventional device, when the rotating body rotates in the forward direction, the fB force is 190 degrees in advance of the pulse phase, as shown by the period TF in FIG.
The phase will be delayed by degrees. The speed increase/decrease of the rotating body corresponds to the period of the pulse f A r f H.

In this conventional device, when switching the rotation direction from forward rotation to reverse rotation or vice versa (period To in FIG. 2), the rotation direction or fB
There is a 180 degree phase shift between the two, resulting in a state where the period does not correspond to the rotational speed. For this reason, the speed detection signal changes in a step manner when switching the rotational direction, and when this speed detection signal is used as the speed control amount, it causes disturbances in the torque and speed of the rotating body and increases mechanical fatigue of the rotating body itself. There was a problem.

The present invention has been made in view of the above-mentioned circumstances, and it is an object of the present invention to provide a detection device that can eliminate erroneous speed detection when switching the rotational direction and, in turn, can facilitate speed control.

The present invention detects a change in the rotational direction and removes the speed detection signal at the time of this detection from the speed detection signal train as an error.
It is characterized by

FIG. 3 shows an embodiment of the present invention, and parts that are the same as those in FIG. 1 or have the same functions are designated by the same reference numerals. The rotation direction detector 4 uses the output of the inverter 5 that inverts the pulse fA as an input to the clock terminal C, and uses a D-type flip-flop that receives the pulse fB as the data terminal input. Detection is made in association with set and reset rotation directions based on the phase difference. The exclusive OR circuit 6 receives the outputs DA and DB of the rotational direction detectors 3 and 4 and detects the difference in rotational direction detection time points. The Nant gate 7 obtains the AND signal EXAB of the measuring operation signal SMPL of the rotational speed detector 2 and the output of the exclusive OR circuit 6, and detects that there is a change in the rotational direction during the measuring operation. The R-9 type flip-flop 8 uses the output EXAB of the cant gate 7 as a set input to store changes in the rotational direction during the measurement operation, and obtains a stored content output CHG at the Q output terminal. The signal R3T is a reset/start signal for the rotation speed detector 2 given from the speed control device main body, etc.
This signal is used to reset the flip-flop 8.

The operation of this configuration will be explained using the time chart shown in FIG. The rotation speed detector 2 resets the count each time the signal R5T is applied, restarts counting using the signal f A r f B or a combination thereof, and outputs the count value immediately before the signal R5T as the speed detection signal N. Further, the rotational speed detector 2 generates a signal SMPL during a counting operation based on the signal R5T. When there is a rotational direction change (time 11) during the counting operation due to the signal R5T at time t0, the output DA of the direction detector 3 rises at the rising edge of the signal 1 immediately after that (time 11), and then the signal 1 rises. At the falling edge of (time ts), the output DB of the direction detector 4 rises. This results in output DA
The output of the exclusive OR circuit 6 is set to logic "1" by the time difference between and DB.
" is taken out, and the output becomes the set signal of the flip 70 knob 8 when present in the SMPL during the measurement operation, and the signal S during the measurement operation is output as the output CHG of the flip flop 8.
It is possible to inform the main body of the control device that the speed detection signal in the MPL is erroneous. Therefore, on the control device side, the actual speed of the rotating body can be determined by ignoring the speed detection signal N when the signal CHG is established as an error, or by performing control calculations using the speed detection signal immediately before or after it. Speed control can be performed using matched speed detection signals.

In addition, as in the above case where the rotation direction is from normal to reverse,
Similarly, the signal CHG can be obtained when the direction changes from reverse rotation to forward rotation (time t4). Also, the signal f A + f
Similarly to the case where the speed is detected from the frequency of signal B, when the speed is detected from the period of the signal +fB shown in FIG. 5, the speed detection signal at the time of direction change (times t1 to t4) can be removed. In FIG. 5, T1 indicates a normal speed detection cycle, and T, , T indicates an incorrect cycle due to a change in the rotational direction.

As described above, according to the present invention, in speed/rotation direction detection using two-phase pulse pickup, errors in the speed detection signal due to changes in rotation direction can be reliably removed and speed control can be made appropriate. Furthermore, in terms of configuration, only a few logic elements need to be added to the conventional device.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of a conventional rotational speed/direction detection device.
Fig. 2 is a time chart for explaining the operation of Fig. 1, Fig. 3 is a circuit configuration diagram 1 showing an embodiment of the present invention, Fig. 4 is a time chart of Fig. 3, and Fig. 5 is a diagram of the present invention. 2 is a time chart for explaining in detail. 1...2-phase pulse pick-up 2...
...Rotation speed detector 3.4...Rotation direction detector 6...Exclusive OR circuit 8...
...R-3 type flip 70 tube Figure 1 Figure 2 υ-T. --J Shi-TF □TR□

Claims (1)

[Claims] (1) A rotational speed detector that detects the rotational speed of a rotating body from the frequency or period of a pulse output signal of a two-phase pulse pickup, and a rotational direction detector that detects a rotational direction based on a phase difference between the pulse output signals. means for obtaining a signal that, if the rotation speed detector is in a speed detection operation when the rotation direction detector detects a change in the rotation direction of the rotating body, makes the speed detection signal caused by the speed detection operation an error. A rotational speed/direction detection device characterized by: