JPS62106372A - Number-of-rotation detecting circuit - Google Patents

Abstract

PURPOSE:To detect a rotational speed within a short time with good accuracy, by a method wherein the frequency of a rotation pulse signal having a constant pulse rate P per one rotation generated from rotary machinery to obtain the frequency divided pulse which is, in turn, counted for a predetermined time corresponding to M/P by a counter circuit. CONSTITUTION:The frequency of the rotary pulse signal generated from a motor is divided by a frequency dividing circuit 1 and a frequency divided output pulse is counted by a counter circuit 2. An initializing signal 6a and a holding signal 6b are respectively inputted to the circuit 2 and a holding circuit 3 from a counter circuit 6. The rotational speed of the motor is set to N rpm and the frequency dividing ratio of the circuit 1 is set to 1/M. The circuit 2 counts the pulse initialized by the signal 6a and divided in frequency to supply the count value to the circuit 3. The time required until the signal 6b is outputted from the circuit 6 after the signal 6a is outputted, that is, a count time (t) is set to M/P. The count value (n) during the time (t) coincides with a rotational speed N and the output of the circuit 3 is displayed on a display circuit 5 through a drive circuit 4 to make it possible to detect the rotational speed within a short time with good accuracy.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention counts a constant number of nine pulse signals per revolution generated from a rotating device such as an electric motor (hereinafter referred to as a motor), and calculates its rotational speed. The present invention relates to a rotation speed detection circuit comprising a rotation speed detection circuit.

[Conventional technology]

The rotational speed of a motor, etc. (generally the number of revolutions per minute (rl) m)
) The following methods are generally used to detect .

(1) Count one pulse per revolution generated by the motor for a certain period of time (in seconds) and convert it to the number of revolutions per minute. When the pulse count value is n, the rotation speed (rpm)
=n-7-.

(2) By counting the clock pulses of a constant frequency at the pulse interval time of one pulse per revolution generated by the motor, the pulse interval (time required for one revolution) is detected, and the reciprocal of the result is calculated. Find the rotation speed.

(31 Count P pulses per rotation generated from the motor for a certain period of time (seconds) and convert it to a count value per minute,
Divide the result by P to find the rotational speed. When the pulse count value is n, the number of rotations (rpm)=n--T--.

[Problem that the invention seeks to solve]

Next, we will discuss the problems with these methods.

In the case of method (1), when the rotational speed of the motor is low, it is necessary to take a correspondingly long pulse counting time, and the detection accuracy is generally low.

Furthermore, even if the rotational speed changes over a wide range, the pulse counting time must be set based on the lower limit value, so it takes a relatively long time to detect the change in rotational speed. It is difficult to follow and detect the poem immediately.

In the case of method (2), the time required to detect the rotation speed depends on the rotation speed itself8. Therefore, low-speed rotation requires a relatively long time to detect, and high-speed rotation requires a sufficient clock pulse frequency. If the value is not high, there is a problem that the detection accuracy decreases.

In the case of method (3), it is an improved method of (1),
Compared to this, the counting time can be shortened and the detection accuracy is generally improved. However, the counted value cannot be used as is,
Multiplication and division operations are required.

The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional motor, and an object of the present invention is to provide a rotation speed detection circuit in which the count value directly represents the rotation speed of the motor, and there is no need for multiplication and division operations.

[Means for Solving the Problems] The rotation speed detection circuit of the present invention detects 1 generated from rotating equipment.
A counting circuit that counts pulses obtained by dividing a rotational pulse signal with a constant number of pulses P per rotation by 1/M, a timing circuit that counts a predetermined time corresponding to M/P, and a counter circuit that counts pulses obtained by dividing a rotational pulse signal with a constant number of pulses P per rotation by 1/M; A means for detecting the counting results is provided.

[Effect]

This invention operates by counting one rotation generated from a rotating device so that the counting result indicates the rotational speed itself.

〔Example〕

Hereinafter, implementation of the rotation speed detection circuit of the present invention will be explained based on the drawings. The figure is a block diagram showing the configuration of one embodiment. The illustrated embodiment has been further improved so that it can be applied to the method (3) above, and is a rotational pulse signal (P pulse/
1 rotation), detects and displays the rotation speed.

In this figure, a rotational pulse (g) generated from a rotating device such as a motor is input to a frequency dividing circuit 1 and frequency-divided.The divided output pulses of the frequency dividing circuit 1 are counted by a counting circuit 2.

The counting circuit 2 and the holding circuit 3 are connected to the output terminal of the timing circuit 6, and the counting circuit 2 receives an initialization signal 6a, and the holding circuit 3 receives a holding signal 6b. There is. The output of the holding circuit 3 is sent to the drive circuit 4. This drive circuit 4 drives the display circuit 5.

Next, the operation of the rotation speed detection circuit of the present invention will be explained.

Now, let the total rotational speed of the motor be N rpm, and the frequency dividing circuit 1
Assume that the division ratio of is 1/M. The counting circuit 2 is initialized by the initialization signal from the timer circuit 6, counts the frequency-divided pulses, and supplies the counted value to the holding circuit 3. The clock circuit 6 outputs a holding signal 6b after a predetermined time after the counting circuit 2 is initialized.
is supplied to the holding circuit 3, and the count value of the counting circuit 2 at that time is held.

Immediately following this, the counting circuit 2 is initialized with the initialization signal 6a from the timer circuit 6, and the next period of counting begins.These holding and initializations are performed by the timer circuit 6 at regular time intervals.

Here, the time from when the clock circuit 6 outputs the initialization signal to when the hold signal is output, that is, the counting time t, is t=
If it is set to be M/P, the count value n during time t(7) becomes n=(PN/M)·(M/P)=N, which coincides with the rotational speed N.

Therefore, this counting result is directly transmitted to the drive circuit 4, for example.
If the rotational speed is displayed on the circuit 5 through the rotation speed, the rotational speed can be detected, and there is no need for multiplication or tilling.

Furthermore, the frequency division ratio (1/M) and the counting time t are set as t = M
If the relationship of /P is maintained while switching is possible, the counting time can be set according to the rotational speed or the required detection accuracy.

〔Effect of the invention〕

As described above, according to the rotation speed detection circuit of the present invention,
Since the rotational speed of rotating equipment such as motors is directly obtained as a counting result, there is no need for multiplication/division calculations, and the rotational speed can be detected with high precision in a relatively short time.

[Brief explanation of drawings]

The figure is a block diagram of one embodiment of the rotation speed detection circuit of the present invention. DESCRIPTION OF SYMBOLS 1... Frequency dividing circuit, 2... Counting circuit, 3... Holding circuit, 4... Driving circuit, 5... Display circuit, 6... Timing circuit.

Claims (1)

[Claims] a frequency dividing circuit that receives a rotational pulse signal with a constant number of pulses P per rotation output from a rotating device and divides it into 1/M; a counting circuit that counts the output pulses of the frequency dividing circuit;
a clock circuit that initializes the counting circuit by sending an initialization signal to the counting circuit and counts a predetermined time corresponding to the M/P; and means for detecting the count value of the counting circuit during the predetermined time. Equipped with a rotation speed detection circuit.